Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

21 files changed, 20593 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/Makefile b/fs/ocfs2/dlm/Makefile
new file mode 100644
index 000000000..5e700b45d
--- /dev/null
+++ b/fs/ocfs2/dlm/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_OCFS2_FS_O2CB) += ocfs2_dlm.o
+
+ocfs2_dlm-objs := dlmdomain.o dlmdebug.o dlmthread.o dlmrecovery.o \
+	dlmmaster.o dlmast.o dlmconvert.o dlmlock.o dlmunlock.o
diff --git a/fs/ocfs2/dlm/dlmapi.h b/fs/ocfs2/dlm/dlmapi.h
new file mode 100644
index 000000000..bae60ca26
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmapi.h
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmapi.h
+ *
+ * externally exported dlm interfaces
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+#ifndef DLMAPI_H
+#define DLMAPI_H
+
+struct dlm_lock;
+struct dlm_ctxt;
+
+/* NOTE: changes made to this enum should be reflected in dlmdebug.c */
+enum dlm_status {
+	DLM_NORMAL = 0,           /*  0: request in progress */
+	DLM_GRANTED,              /*  1: request granted */
+	DLM_DENIED,               /*  2: request denied */
+	DLM_DENIED_NOLOCKS,       /*  3: request denied, out of system resources */
+	DLM_WORKING,              /*  4: async request in progress */
+	DLM_BLOCKED,              /*  5: lock request blocked */
+	DLM_BLOCKED_ORPHAN,       /*  6: lock request blocked by a orphan lock*/
+	DLM_DENIED_GRACE_PERIOD,  /*  7: topological change in progress */
+	DLM_SYSERR,               /*  8: system error */
+	DLM_NOSUPPORT,            /*  9: unsupported */
+	DLM_CANCELGRANT,          /* 10: can't cancel convert: already granted */
+	DLM_IVLOCKID,             /* 11: bad lockid */
+	DLM_SYNC,                 /* 12: synchronous request granted */
+	DLM_BADTYPE,              /* 13: bad resource type */
+	DLM_BADRESOURCE,          /* 14: bad resource handle */
+	DLM_MAXHANDLES,           /* 15: no more resource handles */
+	DLM_NOCLINFO,             /* 16: can't contact cluster manager */
+	DLM_NOLOCKMGR,            /* 17: can't contact lock manager */
+	DLM_NOPURGED,             /* 18: can't contact purge daemon */
+	DLM_BADARGS,              /* 19: bad api args */
+	DLM_VOID,                 /* 20: no status */
+	DLM_NOTQUEUED,            /* 21: NOQUEUE was specified and request failed */
+	DLM_IVBUFLEN,             /* 22: invalid resource name length */
+	DLM_CVTUNGRANT,           /* 23: attempted to convert ungranted lock */
+	DLM_BADPARAM,             /* 24: invalid lock mode specified */
+	DLM_VALNOTVALID,          /* 25: value block has been invalidated */
+	DLM_REJECTED,             /* 26: request rejected, unrecognized client */
+	DLM_ABORT,                /* 27: blocked lock request cancelled */
+	DLM_CANCEL,               /* 28: conversion request cancelled */
+	DLM_IVRESHANDLE,          /* 29: invalid resource handle */
+	DLM_DEADLOCK,             /* 30: deadlock recovery refused this request */
+	DLM_DENIED_NOASTS,        /* 31: failed to allocate AST */
+	DLM_FORWARD,              /* 32: request must wait for primary's response */
+	DLM_TIMEOUT,              /* 33: timeout value for lock has expired */
+	DLM_IVGROUPID,            /* 34: invalid group specification */
+	DLM_VERS_CONFLICT,        /* 35: version conflicts prevent request handling */
+	DLM_BAD_DEVICE_PATH,      /* 36: Locks device does not exist or path wrong */
+	DLM_NO_DEVICE_PERMISSION, /* 37: Client has insufficient pers for device */
+	DLM_NO_CONTROL_DEVICE,    /* 38: Cannot set options on opened device */
+
+	DLM_RECOVERING,           /* 39: extension, allows caller to fail a lock
+				     request if it is being recovered */
+	DLM_MIGRATING,            /* 40: extension, allows caller to fail a lock
+				     request if it is being migrated */
+	DLM_MAXSTATS,             /* 41: upper limit for return code validation */
+};
+
+/* for pretty-printing dlm_status error messages */
+const char *dlm_errmsg(enum dlm_status err);
+/* for pretty-printing dlm_status error names */
+const char *dlm_errname(enum dlm_status err);
+
+/* Eventually the DLM will use standard errno values, but in the
+ * meantime this lets us track dlm errors as they bubble up. When we
+ * bring its error reporting into line with the rest of the stack,
+ * these can just be replaced with calls to mlog_errno. */
+#define dlm_error(st) do {						\
+	if ((st) != DLM_RECOVERING &&					\
+	    (st) != DLM_MIGRATING &&					\
+	    (st) != DLM_FORWARD)					\
+		mlog(ML_ERROR, "dlm status = %s\n", dlm_errname((st)));	\
+} while (0)
+
+#define DLM_LKSB_UNUSED1           0x01
+#define DLM_LKSB_PUT_LVB           0x02
+#define DLM_LKSB_GET_LVB           0x04
+#define DLM_LKSB_UNUSED2           0x08
+#define DLM_LKSB_UNUSED3           0x10
+#define DLM_LKSB_UNUSED4           0x20
+#define DLM_LKSB_UNUSED5           0x40
+#define DLM_LKSB_UNUSED6           0x80
+
+#define DLM_LVB_LEN  64
+
+/* Callers are only allowed access to the lvb and status members of
+ * this struct. */
+struct dlm_lockstatus {
+	enum dlm_status status;
+	u32 flags;
+	struct dlm_lock *lockid;
+	char lvb[DLM_LVB_LEN];
+};
+
+/* Valid lock modes. */
+#define LKM_IVMODE      (-1)            /* invalid mode */
+#define LKM_NLMODE      0               /* null lock */
+#define LKM_CRMODE      1               /* concurrent read    unsupported */
+#define LKM_CWMODE      2               /* concurrent write   unsupported */
+#define LKM_PRMODE      3               /* protected read */
+#define LKM_PWMODE      4               /* protected write    unsupported */
+#define LKM_EXMODE      5               /* exclusive */
+#define LKM_MAXMODE     5
+#define LKM_MODEMASK    0xff
+
+/* Flags passed to dlmlock and dlmunlock:
+ * reserved: flags used by the "real" dlm
+ * only a few are supported by this dlm
+ * (U) = unsupported by ocfs2 dlm */
+#define LKM_ORPHAN       0x00000010  /* this lock is orphanable (U) */
+#define LKM_PARENTABLE   0x00000020  /* this lock was orphaned (U) */
+#define LKM_BLOCK        0x00000040  /* blocking lock request (U) */
+#define LKM_LOCAL        0x00000080  /* local lock request */
+#define LKM_VALBLK       0x00000100  /* lock value block request */
+#define LKM_NOQUEUE      0x00000200  /* non blocking request */
+#define LKM_CONVERT      0x00000400  /* conversion request */
+#define LKM_NODLCKWT     0x00000800  /* this lock wont deadlock (U) */
+#define LKM_UNLOCK       0x00001000  /* deallocate this lock */
+#define LKM_CANCEL       0x00002000  /* cancel conversion request */
+#define LKM_DEQALL       0x00004000  /* remove all locks held by proc (U) */
+#define LKM_INVVALBLK    0x00008000  /* invalidate lock value block */
+#define LKM_SYNCSTS      0x00010000  /* return synchronous status if poss (U) */
+#define LKM_TIMEOUT      0x00020000  /* lock request contains timeout (U) */
+#define LKM_SNGLDLCK     0x00040000  /* request can self-deadlock (U) */
+#define LKM_FINDLOCAL    0x00080000  /* find local lock request (U) */
+#define LKM_PROC_OWNED   0x00100000  /* owned by process, not group (U) */
+#define LKM_XID          0x00200000  /* use transaction id for deadlock (U) */
+#define LKM_XID_CONFLICT 0x00400000  /* do not allow lock inheritance (U) */
+#define LKM_FORCE        0x00800000  /* force unlock flag */
+#define LKM_REVVALBLK    0x01000000  /* temporary solution: re-validate
+					lock value block (U) */
+/* unused */
+#define LKM_UNUSED1      0x00000001  /* unused */
+#define LKM_UNUSED2      0x00000002  /* unused */
+#define LKM_UNUSED3      0x00000004  /* unused */
+#define LKM_UNUSED4      0x00000008  /* unused */
+#define LKM_UNUSED5      0x02000000  /* unused */
+#define LKM_UNUSED6      0x04000000  /* unused */
+#define LKM_UNUSED7      0x08000000  /* unused */
+
+/* ocfs2 extensions: internal only
+ * should never be used by caller */
+#define LKM_MIGRATION    0x10000000  /* extension: lockres is to be migrated
+					to another node */
+#define LKM_PUT_LVB      0x20000000  /* extension: lvb is being passed
+					should be applied to lockres */
+#define LKM_GET_LVB      0x40000000  /* extension: lvb should be copied
+					from lockres when lock is granted */
+#define LKM_RECOVERY     0x80000000  /* extension: flag for recovery lock
+					used to avoid recovery rwsem */
+
+
+typedef void (dlm_astlockfunc_t)(void *);
+typedef void (dlm_bastlockfunc_t)(void *, int);
+typedef void (dlm_astunlockfunc_t)(void *, enum dlm_status);
+
+enum dlm_status dlmlock(struct dlm_ctxt *dlm,
+			int mode,
+			struct dlm_lockstatus *lksb,
+			int flags,
+			const char *name,
+			int namelen,
+			dlm_astlockfunc_t *ast,
+			void *data,
+			dlm_bastlockfunc_t *bast);
+
+enum dlm_status dlmunlock(struct dlm_ctxt *dlm,
+			  struct dlm_lockstatus *lksb,
+			  int flags,
+			  dlm_astunlockfunc_t *unlockast,
+			  void *data);
+
+struct dlm_protocol_version {
+	u8 pv_major;
+	u8 pv_minor;
+};
+struct dlm_ctxt * dlm_register_domain(const char *domain, u32 key,
+				      struct dlm_protocol_version *fs_proto);
+
+void dlm_unregister_domain(struct dlm_ctxt *dlm);
+
+void dlm_print_one_lock(struct dlm_lock *lockid);
+
+typedef void (dlm_eviction_func)(int, void *);
+struct dlm_eviction_cb {
+	struct list_head        ec_item;
+	dlm_eviction_func       *ec_func;
+	void                    *ec_data;
+};
+void dlm_setup_eviction_cb(struct dlm_eviction_cb *cb,
+			   dlm_eviction_func *f,
+			   void *data);
+void dlm_register_eviction_cb(struct dlm_ctxt *dlm,
+			      struct dlm_eviction_cb *cb);
+void dlm_unregister_eviction_cb(struct dlm_eviction_cb *cb);
+
+#endif /* DLMAPI_H */
diff --git a/fs/ocfs2/dlm/dlmast.c b/fs/ocfs2/dlm/dlmast.c
new file mode 100644
index 000000000..c681ba957
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmast.c
@@ -0,0 +1,475 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmast.c
+ *
+ * AST and BAST functionality for local and remote nodes
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/spinlock.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+
+#define MLOG_MASK_PREFIX ML_DLM
+#include "../cluster/masklog.h"
+
+static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			   struct dlm_lock *lock);
+static int dlm_should_cancel_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
+
+/* Should be called as an ast gets queued to see if the new
+ * lock level will obsolete a pending bast.
+ * For example, if dlm_thread queued a bast for an EX lock that
+ * was blocking another EX, but before sending the bast the
+ * lock owner downconverted to NL, the bast is now obsolete.
+ * Only the ast should be sent.
+ * This is needed because the lock and convert paths can queue
+ * asts out-of-band (not waiting for dlm_thread) in order to
+ * allow for LKM_NOQUEUE to get immediate responses. */
+static int dlm_should_cancel_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
+{
+	assert_spin_locked(&dlm->ast_lock);
+	assert_spin_locked(&lock->spinlock);
+
+	if (lock->ml.highest_blocked == LKM_IVMODE)
+		return 0;
+	BUG_ON(lock->ml.highest_blocked == LKM_NLMODE);
+
+	if (lock->bast_pending &&
+	    list_empty(&lock->bast_list))
+		/* old bast already sent, ok */
+		return 0;
+
+	if (lock->ml.type == LKM_EXMODE)
+		/* EX blocks anything left, any bast still valid */
+		return 0;
+	else if (lock->ml.type == LKM_NLMODE)
+		/* NL blocks nothing, no reason to send any bast, cancel it */
+		return 1;
+	else if (lock->ml.highest_blocked != LKM_EXMODE)
+		/* PR only blocks EX */
+		return 1;
+
+	return 0;
+}
+
+void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
+{
+	struct dlm_lock_resource *res;
+
+	BUG_ON(!dlm);
+	BUG_ON(!lock);
+
+	res = lock->lockres;
+
+	assert_spin_locked(&dlm->ast_lock);
+
+	if (!list_empty(&lock->ast_list)) {
+		mlog(ML_ERROR, "%s: res %.*s, lock %u:%llu, "
+		     "AST list not empty, pending %d, newlevel %d\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     lock->ast_pending, lock->ml.type);
+		BUG();
+	}
+	if (lock->ast_pending)
+		mlog(0, "%s: res %.*s, lock %u:%llu, AST getting flushed\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)));
+
+	/* putting lock on list, add a ref */
+	dlm_lock_get(lock);
+	spin_lock(&lock->spinlock);
+
+	/* check to see if this ast obsoletes the bast */
+	if (dlm_should_cancel_bast(dlm, lock)) {
+		mlog(0, "%s: res %.*s, lock %u:%llu, Cancelling BAST\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)));
+		lock->bast_pending = 0;
+		list_del_init(&lock->bast_list);
+		lock->ml.highest_blocked = LKM_IVMODE;
+		/* removing lock from list, remove a ref.  guaranteed
+		 * this won't be the last ref because of the get above,
+		 * so res->spinlock will not be taken here */
+		dlm_lock_put(lock);
+		/* free up the reserved bast that we are cancelling.
+		 * guaranteed that this will not be the last reserved
+		 * ast because *both* an ast and a bast were reserved
+		 * to get to this point.  the res->spinlock will not be
+		 * taken here */
+		dlm_lockres_release_ast(dlm, res);
+	}
+	list_add_tail(&lock->ast_list, &dlm->pending_asts);
+	lock->ast_pending = 1;
+	spin_unlock(&lock->spinlock);
+}
+
+void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
+{
+	BUG_ON(!dlm);
+	BUG_ON(!lock);
+
+	spin_lock(&dlm->ast_lock);
+	__dlm_queue_ast(dlm, lock);
+	spin_unlock(&dlm->ast_lock);
+}
+
+
+void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
+{
+	struct dlm_lock_resource *res;
+
+	BUG_ON(!dlm);
+	BUG_ON(!lock);
+
+	assert_spin_locked(&dlm->ast_lock);
+
+	res = lock->lockres;
+
+	BUG_ON(!list_empty(&lock->bast_list));
+	if (lock->bast_pending)
+		mlog(0, "%s: res %.*s, lock %u:%llu, BAST getting flushed\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)));
+
+	/* putting lock on list, add a ref */
+	dlm_lock_get(lock);
+	spin_lock(&lock->spinlock);
+	list_add_tail(&lock->bast_list, &dlm->pending_basts);
+	lock->bast_pending = 1;
+	spin_unlock(&lock->spinlock);
+}
+
+static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			   struct dlm_lock *lock)
+{
+	struct dlm_lockstatus *lksb = lock->lksb;
+	BUG_ON(!lksb);
+
+	/* only updates if this node masters the lockres */
+	spin_lock(&res->spinlock);
+	if (res->owner == dlm->node_num) {
+		/* check the lksb flags for the direction */
+		if (lksb->flags & DLM_LKSB_GET_LVB) {
+			mlog(0, "getting lvb from lockres for %s node\n",
+				  lock->ml.node == dlm->node_num ? "master" :
+				  "remote");
+			memcpy(lksb->lvb, res->lvb, DLM_LVB_LEN);
+		}
+		/* Do nothing for lvb put requests - they should be done in
+ 		 * place when the lock is downconverted - otherwise we risk
+ 		 * racing gets and puts which could result in old lvb data
+ 		 * being propagated. We leave the put flag set and clear it
+ 		 * here. In the future we might want to clear it at the time
+ 		 * the put is actually done.
+		 */
+	}
+	spin_unlock(&res->spinlock);
+
+	/* reset any lvb flags on the lksb */
+	lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
+}
+
+void dlm_do_local_ast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+		      struct dlm_lock *lock)
+{
+	dlm_astlockfunc_t *fn;
+
+	mlog(0, "%s: res %.*s, lock %u:%llu, Local AST\n", dlm->name,
+	     res->lockname.len, res->lockname.name,
+	     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)));
+
+	fn = lock->ast;
+	BUG_ON(lock->ml.node != dlm->node_num);
+
+	dlm_update_lvb(dlm, res, lock);
+	(*fn)(lock->astdata);
+}
+
+
+int dlm_do_remote_ast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+		      struct dlm_lock *lock)
+{
+	int ret;
+	struct dlm_lockstatus *lksb;
+	int lksbflags;
+
+	mlog(0, "%s: res %.*s, lock %u:%llu, Remote AST\n", dlm->name,
+	     res->lockname.len, res->lockname.name,
+	     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)));
+
+	lksb = lock->lksb;
+	BUG_ON(lock->ml.node == dlm->node_num);
+
+	lksbflags = lksb->flags;
+	dlm_update_lvb(dlm, res, lock);
+
+	/* lock request came from another node
+	 * go do the ast over there */
+	ret = dlm_send_proxy_ast(dlm, res, lock, lksbflags);
+	return ret;
+}
+
+void dlm_do_local_bast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+		       struct dlm_lock *lock, int blocked_type)
+{
+	dlm_bastlockfunc_t *fn = lock->bast;
+
+	BUG_ON(lock->ml.node != dlm->node_num);
+
+	mlog(0, "%s: res %.*s, lock %u:%llu, Local BAST, blocked %d\n",
+	     dlm->name, res->lockname.len, res->lockname.name,
+	     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+	     blocked_type);
+
+	(*fn)(lock->astdata, blocked_type);
+}
+
+
+
+int dlm_proxy_ast_handler(struct o2net_msg *msg, u32 len, void *data,
+			  void **ret_data)
+{
+	int ret;
+	unsigned int locklen;
+	struct dlm_ctxt *dlm = data;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_lock *lock = NULL;
+	struct dlm_proxy_ast *past = (struct dlm_proxy_ast *) msg->buf;
+	char *name;
+	struct list_head *head = NULL;
+	__be64 cookie;
+	u32 flags;
+	u8 node;
+
+	if (!dlm_grab(dlm)) {
+		dlm_error(DLM_REJECTED);
+		return DLM_REJECTED;
+	}
+
+	mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
+			"Domain %s not fully joined!\n", dlm->name);
+
+	name = past->name;
+	locklen = past->namelen;
+	cookie = past->cookie;
+	flags = be32_to_cpu(past->flags);
+	node = past->node_idx;
+
+	if (locklen > DLM_LOCKID_NAME_MAX) {
+		ret = DLM_IVBUFLEN;
+		mlog(ML_ERROR, "Invalid name length (%d) in proxy ast "
+		     "handler!\n", locklen);
+		goto leave;
+	}
+
+	if ((flags & (LKM_PUT_LVB|LKM_GET_LVB)) ==
+	     (LKM_PUT_LVB|LKM_GET_LVB)) {
+		mlog(ML_ERROR, "Both PUT and GET lvb specified, (0x%x)\n",
+		     flags);
+		ret = DLM_BADARGS;
+		goto leave;
+	}
+
+	mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" :
+		  (flags & LKM_GET_LVB ? "get lvb" : "none"));
+
+	mlog(0, "type=%d, blocked_type=%d\n", past->type, past->blocked_type);
+
+	if (past->type != DLM_AST &&
+	    past->type != DLM_BAST) {
+		mlog(ML_ERROR, "Unknown ast type! %d, cookie=%u:%llu"
+		     "name=%.*s, node=%u\n", past->type,
+		     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
+		     locklen, name, node);
+		ret = DLM_IVLOCKID;
+		goto leave;
+	}
+
+	res = dlm_lookup_lockres(dlm, name, locklen);
+	if (!res) {
+		mlog(0, "Got %sast for unknown lockres! cookie=%u:%llu, "
+		     "name=%.*s, node=%u\n", (past->type == DLM_AST ? "" : "b"),
+		     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
+		     locklen, name, node);
+		ret = DLM_IVLOCKID;
+		goto leave;
+	}
+
+	/* cannot get a proxy ast message if this node owns it */
+	BUG_ON(res->owner == dlm->node_num);
+
+	mlog(0, "%s: res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_RECOVERING) {
+		mlog(0, "Responding with DLM_RECOVERING!\n");
+		ret = DLM_RECOVERING;
+		goto unlock_out;
+	}
+	if (res->state & DLM_LOCK_RES_MIGRATING) {
+		mlog(0, "Responding with DLM_MIGRATING!\n");
+		ret = DLM_MIGRATING;
+		goto unlock_out;
+	}
+	/* try convert queue for both ast/bast */
+	head = &res->converting;
+	lock = NULL;
+	list_for_each_entry(lock, head, list) {
+		if (lock->ml.cookie == cookie)
+			goto do_ast;
+	}
+
+	/* if not on convert, try blocked for ast, granted for bast */
+	if (past->type == DLM_AST)
+		head = &res->blocked;
+	else
+		head = &res->granted;
+
+	list_for_each_entry(lock, head, list) {
+		/* if lock is found but unlock is pending ignore the bast */
+		if (lock->ml.cookie == cookie) {
+			if (lock->unlock_pending)
+				break;
+			goto do_ast;
+		}
+	}
+
+	mlog(0, "Got %sast for unknown lock! cookie=%u:%llu, name=%.*s, "
+	     "node=%u\n", past->type == DLM_AST ? "" : "b",
+	     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
+	     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
+	     locklen, name, node);
+
+	ret = DLM_NORMAL;
+unlock_out:
+	spin_unlock(&res->spinlock);
+	goto leave;
+
+do_ast:
+	ret = DLM_NORMAL;
+	if (past->type == DLM_AST) {
+		/* do not alter lock refcount.  switching lists. */
+		list_move_tail(&lock->list, &res->granted);
+		mlog(0, "%s: res %.*s, lock %u:%llu, Granted type %d => %d\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
+		     lock->ml.type, lock->ml.convert_type);
+
+		if (lock->ml.convert_type != LKM_IVMODE) {
+			lock->ml.type = lock->ml.convert_type;
+			lock->ml.convert_type = LKM_IVMODE;
+		} else {
+			// should already be there....
+		}
+
+		lock->lksb->status = DLM_NORMAL;
+
+		/* if we requested the lvb, fetch it into our lksb now */
+		if (flags & LKM_GET_LVB) {
+			BUG_ON(!(lock->lksb->flags & DLM_LKSB_GET_LVB));
+			memcpy(lock->lksb->lvb, past->lvb, DLM_LVB_LEN);
+		}
+	}
+	spin_unlock(&res->spinlock);
+
+	if (past->type == DLM_AST)
+		dlm_do_local_ast(dlm, res, lock);
+	else
+		dlm_do_local_bast(dlm, res, lock, past->blocked_type);
+
+leave:
+	if (res)
+		dlm_lockres_put(res);
+
+	dlm_put(dlm);
+	return ret;
+}
+
+
+
+int dlm_send_proxy_ast_msg(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			   struct dlm_lock *lock, int msg_type,
+			   int blocked_type, int flags)
+{
+	int ret = 0;
+	struct dlm_proxy_ast past;
+	struct kvec vec[2];
+	size_t veclen = 1;
+	int status;
+
+	mlog(0, "%s: res %.*s, to %u, type %d, blocked_type %d\n", dlm->name,
+	     res->lockname.len, res->lockname.name, lock->ml.node, msg_type,
+	     blocked_type);
+
+	memset(&past, 0, sizeof(struct dlm_proxy_ast));
+	past.node_idx = dlm->node_num;
+	past.type = msg_type;
+	past.blocked_type = blocked_type;
+	past.namelen = res->lockname.len;
+	memcpy(past.name, res->lockname.name, past.namelen);
+	past.cookie = lock->ml.cookie;
+
+	vec[0].iov_len = sizeof(struct dlm_proxy_ast);
+	vec[0].iov_base = &past;
+	if (flags & DLM_LKSB_GET_LVB) {
+		be32_add_cpu(&past.flags, LKM_GET_LVB);
+		vec[1].iov_len = DLM_LVB_LEN;
+		vec[1].iov_base = lock->lksb->lvb;
+		veclen++;
+	}
+
+	ret = o2net_send_message_vec(DLM_PROXY_AST_MSG, dlm->key, vec, veclen,
+				     lock->ml.node, &status);
+	if (ret < 0)
+		mlog(ML_ERROR, "%s: res %.*s, error %d send AST to node %u\n",
+		     dlm->name, res->lockname.len, res->lockname.name, ret,
+		     lock->ml.node);
+	else {
+		if (status == DLM_RECOVERING) {
+			mlog(ML_ERROR, "sent AST to node %u, it thinks this "
+			     "node is dead!\n", lock->ml.node);
+			BUG();
+		} else if (status == DLM_MIGRATING) {
+			mlog(ML_ERROR, "sent AST to node %u, it returned "
+			     "DLM_MIGRATING!\n", lock->ml.node);
+			BUG();
+		} else if (status != DLM_NORMAL && status != DLM_IVLOCKID) {
+			mlog(ML_ERROR, "AST to node %u returned %d!\n",
+			     lock->ml.node, status);
+			/* ignore it */
+		}
+		ret = 0;
+	}
+	return ret;
+}
diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
new file mode 100644
index 000000000..fd2022712
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -0,0 +1,1132 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmcommon.h
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+#ifndef DLMCOMMON_H
+#define DLMCOMMON_H
+
+#include <linux/kref.h>
+
+#define DLM_HB_NODE_DOWN_PRI     (0xf000000)
+#define DLM_HB_NODE_UP_PRI       (0x8000000)
+
+#define DLM_LOCKID_NAME_MAX    32
+
+#define DLM_LOCK_RES_OWNER_UNKNOWN     O2NM_MAX_NODES
+
+#define DLM_HASH_SIZE_DEFAULT	(1 << 17)
+#if DLM_HASH_SIZE_DEFAULT < PAGE_SIZE
+# define DLM_HASH_PAGES		1
+#else
+# define DLM_HASH_PAGES		(DLM_HASH_SIZE_DEFAULT / PAGE_SIZE)
+#endif
+#define DLM_BUCKETS_PER_PAGE	(PAGE_SIZE / sizeof(struct hlist_head))
+#define DLM_HASH_BUCKETS	(DLM_HASH_PAGES * DLM_BUCKETS_PER_PAGE)
+
+/* Intended to make it easier for us to switch out hash functions */
+#define dlm_lockid_hash(_n, _l) full_name_hash(NULL, _n, _l)
+
+enum dlm_mle_type {
+	DLM_MLE_BLOCK = 0,
+	DLM_MLE_MASTER = 1,
+	DLM_MLE_MIGRATION = 2,
+	DLM_MLE_NUM_TYPES = 3,
+};
+
+struct dlm_master_list_entry {
+	struct hlist_node master_hash_node;
+	struct list_head hb_events;
+	struct dlm_ctxt *dlm;
+	spinlock_t spinlock;
+	wait_queue_head_t wq;
+	atomic_t woken;
+	struct kref mle_refs;
+	int inuse;
+	unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	u8 master;
+	u8 new_master;
+	enum dlm_mle_type type;
+	struct o2hb_callback_func mle_hb_up;
+	struct o2hb_callback_func mle_hb_down;
+	struct dlm_lock_resource *mleres;
+	unsigned char mname[DLM_LOCKID_NAME_MAX];
+	unsigned int mnamelen;
+	unsigned int mnamehash;
+};
+
+enum dlm_ast_type {
+	DLM_AST = 0,
+	DLM_BAST = 1,
+	DLM_ASTUNLOCK = 2,
+};
+
+
+#define LKM_VALID_FLAGS (LKM_VALBLK | LKM_CONVERT | LKM_UNLOCK | \
+			 LKM_CANCEL | LKM_INVVALBLK | LKM_FORCE | \
+			 LKM_RECOVERY | LKM_LOCAL | LKM_NOQUEUE)
+
+#define DLM_RECOVERY_LOCK_NAME       "$RECOVERY"
+#define DLM_RECOVERY_LOCK_NAME_LEN   9
+
+static inline int dlm_is_recovery_lock(const char *lock_name, int name_len)
+{
+	if (name_len == DLM_RECOVERY_LOCK_NAME_LEN &&
+	    memcmp(lock_name, DLM_RECOVERY_LOCK_NAME, name_len)==0)
+		return 1;
+	return 0;
+}
+
+#define DLM_RECO_STATE_ACTIVE    0x0001
+#define DLM_RECO_STATE_FINALIZE  0x0002
+
+struct dlm_recovery_ctxt
+{
+	struct list_head resources;
+	struct list_head node_data;
+	u8  new_master;
+	u8  dead_node;
+	u16 state;
+	unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	wait_queue_head_t event;
+};
+
+enum dlm_ctxt_state {
+	DLM_CTXT_NEW = 0,
+	DLM_CTXT_JOINED = 1,
+	DLM_CTXT_IN_SHUTDOWN = 2,
+	DLM_CTXT_LEAVING = 3,
+};
+
+struct dlm_ctxt
+{
+	struct list_head list;
+	struct hlist_head **lockres_hash;
+	struct list_head dirty_list;
+	struct list_head purge_list;
+	struct list_head pending_asts;
+	struct list_head pending_basts;
+	struct list_head tracking_list;
+	unsigned int purge_count;
+	spinlock_t spinlock;
+	spinlock_t ast_lock;
+	spinlock_t track_lock;
+	char *name;
+	u8 node_num;
+	u32 key;
+	u8  joining_node;
+	u8 migrate_done; /* set to 1 means node has migrated all lock resources */
+	wait_queue_head_t dlm_join_events;
+	unsigned long live_nodes_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long domain_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long exit_domain_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long recovery_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	struct dlm_recovery_ctxt reco;
+	spinlock_t master_lock;
+	struct hlist_head **master_hash;
+	struct list_head mle_hb_events;
+
+	/* these give a really vague idea of the system load */
+	atomic_t mle_tot_count[DLM_MLE_NUM_TYPES];
+	atomic_t mle_cur_count[DLM_MLE_NUM_TYPES];
+	atomic_t res_tot_count;
+	atomic_t res_cur_count;
+
+	struct dentry *dlm_debugfs_subroot;
+
+	/* NOTE: Next three are protected by dlm_domain_lock */
+	struct kref dlm_refs;
+	enum dlm_ctxt_state dlm_state;
+	unsigned int num_joins;
+
+	struct o2hb_callback_func dlm_hb_up;
+	struct o2hb_callback_func dlm_hb_down;
+	struct task_struct *dlm_thread_task;
+	struct task_struct *dlm_reco_thread_task;
+	struct workqueue_struct *dlm_worker;
+	wait_queue_head_t dlm_thread_wq;
+	wait_queue_head_t dlm_reco_thread_wq;
+	wait_queue_head_t ast_wq;
+	wait_queue_head_t migration_wq;
+
+	struct work_struct dispatched_work;
+	struct list_head work_list;
+	spinlock_t work_lock;
+	struct list_head dlm_domain_handlers;
+	struct list_head	dlm_eviction_callbacks;
+
+	/* The filesystem specifies this at domain registration.  We
+	 * cache it here to know what to tell other nodes. */
+	struct dlm_protocol_version fs_locking_proto;
+	/* This is the inter-dlm communication version */
+	struct dlm_protocol_version dlm_locking_proto;
+};
+
+static inline struct hlist_head *dlm_lockres_hash(struct dlm_ctxt *dlm, unsigned i)
+{
+	return dlm->lockres_hash[(i / DLM_BUCKETS_PER_PAGE) % DLM_HASH_PAGES] + (i % DLM_BUCKETS_PER_PAGE);
+}
+
+static inline struct hlist_head *dlm_master_hash(struct dlm_ctxt *dlm,
+						 unsigned i)
+{
+	return dlm->master_hash[(i / DLM_BUCKETS_PER_PAGE) % DLM_HASH_PAGES] +
+			(i % DLM_BUCKETS_PER_PAGE);
+}
+
+/* these keventd work queue items are for less-frequently
+ * called functions that cannot be directly called from the
+ * net message handlers for some reason, usually because
+ * they need to send net messages of their own. */
+void dlm_dispatch_work(struct work_struct *work);
+
+struct dlm_lock_resource;
+struct dlm_work_item;
+
+typedef void (dlm_workfunc_t)(struct dlm_work_item *, void *);
+
+struct dlm_request_all_locks_priv
+{
+	u8 reco_master;
+	u8 dead_node;
+};
+
+struct dlm_mig_lockres_priv
+{
+	struct dlm_lock_resource *lockres;
+	u8 real_master;
+	u8 extra_ref;
+};
+
+struct dlm_assert_master_priv
+{
+	struct dlm_lock_resource *lockres;
+	u8 request_from;
+	u32 flags;
+	unsigned ignore_higher:1;
+};
+
+struct dlm_deref_lockres_priv
+{
+	struct dlm_lock_resource *deref_res;
+	u8 deref_node;
+};
+
+struct dlm_work_item
+{
+	struct list_head list;
+	dlm_workfunc_t *func;
+	struct dlm_ctxt *dlm;
+	void *data;
+	union {
+		struct dlm_request_all_locks_priv ral;
+		struct dlm_mig_lockres_priv ml;
+		struct dlm_assert_master_priv am;
+		struct dlm_deref_lockres_priv dl;
+	} u;
+};
+
+static inline void dlm_init_work_item(struct dlm_ctxt *dlm,
+				      struct dlm_work_item *i,
+				      dlm_workfunc_t *f, void *data)
+{
+	memset(i, 0, sizeof(*i));
+	i->func = f;
+	INIT_LIST_HEAD(&i->list);
+	i->data = data;
+	i->dlm = dlm;  /* must have already done a dlm_grab on this! */
+}
+
+
+
+static inline void __dlm_set_joining_node(struct dlm_ctxt *dlm,
+					  u8 node)
+{
+	assert_spin_locked(&dlm->spinlock);
+
+	dlm->joining_node = node;
+	wake_up(&dlm->dlm_join_events);
+}
+
+#define DLM_LOCK_RES_UNINITED             0x00000001
+#define DLM_LOCK_RES_RECOVERING           0x00000002
+#define DLM_LOCK_RES_READY                0x00000004
+#define DLM_LOCK_RES_DIRTY                0x00000008
+#define DLM_LOCK_RES_IN_PROGRESS          0x00000010
+#define DLM_LOCK_RES_MIGRATING            0x00000020
+#define DLM_LOCK_RES_DROPPING_REF         0x00000040
+#define DLM_LOCK_RES_BLOCK_DIRTY          0x00001000
+#define DLM_LOCK_RES_SETREF_INPROG        0x00002000
+#define DLM_LOCK_RES_RECOVERY_WAITING     0x00004000
+
+/* max milliseconds to wait to sync up a network failure with a node death */
+#define DLM_NODE_DEATH_WAIT_MAX (5 * 1000)
+
+#define DLM_PURGE_INTERVAL_MS   (8 * 1000)
+
+struct dlm_lock_resource
+{
+	/* WARNING: Please see the comment in dlm_init_lockres before
+	 * adding fields here. */
+	struct hlist_node hash_node;
+	struct qstr lockname;
+	struct kref      refs;
+
+	/*
+	 * Please keep granted, converting, and blocked in this order,
+	 * as some funcs want to iterate over all lists.
+	 *
+	 * All four lists are protected by the hash's reference.
+	 */
+	struct list_head granted;
+	struct list_head converting;
+	struct list_head blocked;
+	struct list_head purge;
+
+	/*
+	 * These two lists require you to hold an additional reference
+	 * while they are on the list.
+	 */
+	struct list_head dirty;
+	struct list_head recovering; // dlm_recovery_ctxt.resources list
+
+	/* Added during init and removed during release */
+	struct list_head tracking;	/* dlm->tracking_list */
+
+	/* unused lock resources have their last_used stamped and are
+	 * put on a list for the dlm thread to run. */
+	unsigned long    last_used;
+
+	struct dlm_ctxt *dlm;
+
+	unsigned migration_pending:1;
+	atomic_t asts_reserved;
+	spinlock_t spinlock;
+	wait_queue_head_t wq;
+	u8  owner;              //node which owns the lock resource, or unknown
+	u16 state;
+	char lvb[DLM_LVB_LEN];
+	unsigned int inflight_locks;
+	unsigned int inflight_assert_workers;
+	unsigned long refmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+};
+
+struct dlm_migratable_lock
+{
+	__be64 cookie;
+
+	/* these 3 are just padding for the in-memory structure, but
+	 * list and flags are actually used when sent over the wire */
+	__be16 pad1;
+	u8 list;  // 0=granted, 1=converting, 2=blocked
+	u8 flags;
+
+	s8 type;
+	s8 convert_type;
+	s8 highest_blocked;
+	u8 node;
+};  // 16 bytes
+
+struct dlm_lock
+{
+	struct dlm_migratable_lock ml;
+
+	struct list_head list;
+	struct list_head ast_list;
+	struct list_head bast_list;
+	struct dlm_lock_resource *lockres;
+	spinlock_t spinlock;
+	struct kref lock_refs;
+
+	// ast and bast must be callable while holding a spinlock!
+	dlm_astlockfunc_t *ast;
+	dlm_bastlockfunc_t *bast;
+	void *astdata;
+	struct dlm_lockstatus *lksb;
+	unsigned ast_pending:1,
+		 bast_pending:1,
+		 convert_pending:1,
+		 lock_pending:1,
+		 cancel_pending:1,
+		 unlock_pending:1,
+		 lksb_kernel_allocated:1;
+};
+
+enum dlm_lockres_list {
+	DLM_GRANTED_LIST = 0,
+	DLM_CONVERTING_LIST = 1,
+	DLM_BLOCKED_LIST = 2,
+};
+
+static inline int dlm_lvb_is_empty(char *lvb)
+{
+	int i;
+	for (i=0; i<DLM_LVB_LEN; i++)
+		if (lvb[i])
+			return 0;
+	return 1;
+}
+
+static inline char *dlm_list_in_text(enum dlm_lockres_list idx)
+{
+	if (idx == DLM_GRANTED_LIST)
+		return "granted";
+	else if (idx == DLM_CONVERTING_LIST)
+		return "converting";
+	else if (idx == DLM_BLOCKED_LIST)
+		return "blocked";
+	else
+		return "unknown";
+}
+
+static inline struct list_head *
+dlm_list_idx_to_ptr(struct dlm_lock_resource *res, enum dlm_lockres_list idx)
+{
+	struct list_head *ret = NULL;
+	if (idx == DLM_GRANTED_LIST)
+		ret = &res->granted;
+	else if (idx == DLM_CONVERTING_LIST)
+		ret = &res->converting;
+	else if (idx == DLM_BLOCKED_LIST)
+		ret = &res->blocked;
+	else
+		BUG();
+	return ret;
+}
+
+
+
+
+struct dlm_node_iter
+{
+	unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	int curnode;
+};
+
+
+enum {
+	DLM_MASTER_REQUEST_MSG		= 500,
+	DLM_UNUSED_MSG1			= 501,
+	DLM_ASSERT_MASTER_MSG		= 502,
+	DLM_CREATE_LOCK_MSG		= 503,
+	DLM_CONVERT_LOCK_MSG		= 504,
+	DLM_PROXY_AST_MSG		= 505,
+	DLM_UNLOCK_LOCK_MSG		= 506,
+	DLM_DEREF_LOCKRES_MSG		= 507,
+	DLM_MIGRATE_REQUEST_MSG		= 508,
+	DLM_MIG_LOCKRES_MSG		= 509,
+	DLM_QUERY_JOIN_MSG		= 510,
+	DLM_ASSERT_JOINED_MSG		= 511,
+	DLM_CANCEL_JOIN_MSG		= 512,
+	DLM_EXIT_DOMAIN_MSG		= 513,
+	DLM_MASTER_REQUERY_MSG		= 514,
+	DLM_LOCK_REQUEST_MSG		= 515,
+	DLM_RECO_DATA_DONE_MSG		= 516,
+	DLM_BEGIN_RECO_MSG		= 517,
+	DLM_FINALIZE_RECO_MSG		= 518,
+	DLM_QUERY_REGION		= 519,
+	DLM_QUERY_NODEINFO		= 520,
+	DLM_BEGIN_EXIT_DOMAIN_MSG	= 521,
+	DLM_DEREF_LOCKRES_DONE		= 522,
+};
+
+struct dlm_reco_node_data
+{
+	int state;
+	u8 node_num;
+	struct list_head list;
+};
+
+enum {
+	DLM_RECO_NODE_DATA_DEAD = -1,
+	DLM_RECO_NODE_DATA_INIT = 0,
+	DLM_RECO_NODE_DATA_REQUESTING = 1,
+	DLM_RECO_NODE_DATA_REQUESTED = 2,
+	DLM_RECO_NODE_DATA_RECEIVING = 3,
+	DLM_RECO_NODE_DATA_DONE = 4,
+	DLM_RECO_NODE_DATA_FINALIZE_SENT = 5,
+};
+
+
+enum {
+	DLM_MASTER_RESP_NO = 0,
+	DLM_MASTER_RESP_YES = 1,
+	DLM_MASTER_RESP_MAYBE = 2,
+	DLM_MASTER_RESP_ERROR = 3,
+};
+
+
+struct dlm_master_request
+{
+	u8 node_idx;
+	u8 namelen;
+	__be16 pad1;
+	__be32 flags;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+#define DLM_ASSERT_RESPONSE_REASSERT       0x00000001
+#define DLM_ASSERT_RESPONSE_MASTERY_REF    0x00000002
+
+#define DLM_ASSERT_MASTER_MLE_CLEANUP      0x00000001
+#define DLM_ASSERT_MASTER_REQUERY          0x00000002
+#define DLM_ASSERT_MASTER_FINISH_MIGRATION 0x00000004
+struct dlm_assert_master
+{
+	u8 node_idx;
+	u8 namelen;
+	__be16 pad1;
+	__be32 flags;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+#define DLM_MIGRATE_RESPONSE_MASTERY_REF   0x00000001
+
+struct dlm_migrate_request
+{
+	u8 master;
+	u8 new_master;
+	u8 namelen;
+	u8 pad1;
+	__be32 pad2;
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+struct dlm_master_requery
+{
+	u8 pad1;
+	u8 pad2;
+	u8 node_idx;
+	u8 namelen;
+	__be32 pad3;
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+#define DLM_MRES_RECOVERY   0x01
+#define DLM_MRES_MIGRATION  0x02
+#define DLM_MRES_ALL_DONE   0x04
+
+/*
+ * We would like to get one whole lockres into a single network
+ * message whenever possible.  Generally speaking, there will be
+ * at most one dlm_lock on a lockres for each node in the cluster,
+ * plus (infrequently) any additional locks coming in from userdlm.
+ *
+ * struct _dlm_lockres_page
+ * {
+ * 	dlm_migratable_lockres mres;
+ * 	dlm_migratable_lock ml[DLM_MAX_MIGRATABLE_LOCKS];
+ * 	u8 pad[DLM_MIG_LOCKRES_RESERVED];
+ * };
+ *
+ * from ../cluster/tcp.h
+ *    O2NET_MAX_PAYLOAD_BYTES  (4096 - sizeof(net_msg))
+ *    (roughly 4080 bytes)
+ * and sizeof(dlm_migratable_lockres) = 112 bytes
+ * and sizeof(dlm_migratable_lock) = 16 bytes
+ *
+ * Choosing DLM_MAX_MIGRATABLE_LOCKS=240 and
+ * DLM_MIG_LOCKRES_RESERVED=128 means we have this:
+ *
+ *  (DLM_MAX_MIGRATABLE_LOCKS * sizeof(dlm_migratable_lock)) +
+ *     sizeof(dlm_migratable_lockres) + DLM_MIG_LOCKRES_RESERVED =
+ *        NET_MAX_PAYLOAD_BYTES
+ *  (240 * 16) + 112 + 128 = 4080
+ *
+ * So a lockres would need more than 240 locks before it would
+ * use more than one network packet to recover.  Not too bad.
+ */
+#define DLM_MAX_MIGRATABLE_LOCKS   240
+
+struct dlm_migratable_lockres
+{
+	u8 master;
+	u8 lockname_len;
+	u8 num_locks;    // locks sent in this structure
+	u8 flags;
+	__be32 total_locks; // locks to be sent for this migration cookie
+	__be64 mig_cookie;  // cookie for this lockres migration
+			 // or zero if not needed
+	// 16 bytes
+	u8 lockname[DLM_LOCKID_NAME_MAX];
+	// 48 bytes
+	u8 lvb[DLM_LVB_LEN];
+	// 112 bytes
+	struct dlm_migratable_lock ml[];  // 16 bytes each, begins at byte 112
+};
+#define DLM_MIG_LOCKRES_MAX_LEN  \
+	(sizeof(struct dlm_migratable_lockres) + \
+	 (sizeof(struct dlm_migratable_lock) * \
+	  DLM_MAX_MIGRATABLE_LOCKS) )
+
+/* from above, 128 bytes
+ * for some undetermined future use */
+#define DLM_MIG_LOCKRES_RESERVED   (O2NET_MAX_PAYLOAD_BYTES - \
+				    DLM_MIG_LOCKRES_MAX_LEN)
+
+struct dlm_create_lock
+{
+	__be64 cookie;
+
+	__be32 flags;
+	u8 pad1;
+	u8 node_idx;
+	s8 requested_type;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+struct dlm_convert_lock
+{
+	__be64 cookie;
+
+	__be32 flags;
+	u8 pad1;
+	u8 node_idx;
+	s8 requested_type;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+
+	s8 lvb[];
+};
+#define DLM_CONVERT_LOCK_MAX_LEN  (sizeof(struct dlm_convert_lock)+DLM_LVB_LEN)
+
+struct dlm_unlock_lock
+{
+	__be64 cookie;
+
+	__be32 flags;
+	__be16 pad1;
+	u8 node_idx;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+
+	s8 lvb[];
+};
+#define DLM_UNLOCK_LOCK_MAX_LEN  (sizeof(struct dlm_unlock_lock)+DLM_LVB_LEN)
+
+struct dlm_proxy_ast
+{
+	__be64 cookie;
+
+	__be32 flags;
+	u8 node_idx;
+	u8 type;
+	u8 blocked_type;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+
+	s8 lvb[];
+};
+#define DLM_PROXY_AST_MAX_LEN  (sizeof(struct dlm_proxy_ast)+DLM_LVB_LEN)
+
+#define DLM_MOD_KEY (0x666c6172)
+enum dlm_query_join_response_code {
+	JOIN_DISALLOW = 0,
+	JOIN_OK = 1,
+	JOIN_OK_NO_MAP = 2,
+	JOIN_PROTOCOL_MISMATCH = 3,
+};
+
+struct dlm_query_join_packet {
+	u8 code;	/* Response code.  dlm_minor and fs_minor
+			   are only valid if this is JOIN_OK */
+	u8 dlm_minor;	/* The minor version of the protocol the
+			   dlm is speaking. */
+	u8 fs_minor;	/* The minor version of the protocol the
+			   filesystem is speaking. */
+	u8 reserved;
+};
+
+union dlm_query_join_response {
+	__be32 intval;
+	struct dlm_query_join_packet packet;
+};
+
+struct dlm_lock_request
+{
+	u8 node_idx;
+	u8 dead_node;
+	__be16 pad1;
+	__be32 pad2;
+};
+
+struct dlm_reco_data_done
+{
+	u8 node_idx;
+	u8 dead_node;
+	__be16 pad1;
+	__be32 pad2;
+
+	/* unused for now */
+	/* eventually we can use this to attempt
+	 * lvb recovery based on each node's info */
+	u8 reco_lvb[DLM_LVB_LEN];
+};
+
+struct dlm_begin_reco
+{
+	u8 node_idx;
+	u8 dead_node;
+	__be16 pad1;
+	__be32 pad2;
+};
+
+struct dlm_query_join_request
+{
+	u8 node_idx;
+	u8 pad1[2];
+	u8 name_len;
+	struct dlm_protocol_version dlm_proto;
+	struct dlm_protocol_version fs_proto;
+	u8 domain[O2NM_MAX_NAME_LEN];
+	u8 node_map[BITS_TO_BYTES(O2NM_MAX_NODES)];
+};
+
+struct dlm_assert_joined
+{
+	u8 node_idx;
+	u8 pad1[2];
+	u8 name_len;
+	u8 domain[O2NM_MAX_NAME_LEN];
+};
+
+struct dlm_cancel_join
+{
+	u8 node_idx;
+	u8 pad1[2];
+	u8 name_len;
+	u8 domain[O2NM_MAX_NAME_LEN];
+};
+
+struct dlm_query_region {
+	u8 qr_node;
+	u8 qr_numregions;
+	u8 qr_namelen;
+	u8 pad1;
+	u8 qr_domain[O2NM_MAX_NAME_LEN];
+	u8 qr_regions[O2HB_MAX_REGION_NAME_LEN * O2NM_MAX_REGIONS];
+};
+
+struct dlm_node_info {
+	u8 ni_nodenum;
+	u8 pad1;
+	__be16 ni_ipv4_port;
+	__be32 ni_ipv4_address;
+};
+
+struct dlm_query_nodeinfo {
+	u8 qn_nodenum;
+	u8 qn_numnodes;
+	u8 qn_namelen;
+	u8 pad1;
+	u8 qn_domain[O2NM_MAX_NAME_LEN];
+	struct dlm_node_info qn_nodes[O2NM_MAX_NODES];
+};
+
+struct dlm_exit_domain
+{
+	u8 node_idx;
+	u8 pad1[3];
+};
+
+struct dlm_finalize_reco
+{
+	u8 node_idx;
+	u8 dead_node;
+	u8 flags;
+	u8 pad1;
+	__be32 pad2;
+};
+
+struct dlm_deref_lockres
+{
+	u32 pad1;
+	u16 pad2;
+	u8 node_idx;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+enum {
+	DLM_DEREF_RESPONSE_DONE = 0,
+	DLM_DEREF_RESPONSE_INPROG = 1,
+};
+
+struct dlm_deref_lockres_done {
+	u32 pad1;
+	u16 pad2;
+	u8 node_idx;
+	u8 namelen;
+
+	u8 name[O2NM_MAX_NAME_LEN];
+};
+
+static inline enum dlm_status
+__dlm_lockres_state_to_status(struct dlm_lock_resource *res)
+{
+	enum dlm_status status = DLM_NORMAL;
+
+	assert_spin_locked(&res->spinlock);
+
+	if (res->state & (DLM_LOCK_RES_RECOVERING|
+			DLM_LOCK_RES_RECOVERY_WAITING))
+		status = DLM_RECOVERING;
+	else if (res->state & DLM_LOCK_RES_MIGRATING)
+		status = DLM_MIGRATING;
+	else if (res->state & DLM_LOCK_RES_IN_PROGRESS)
+		status = DLM_FORWARD;
+
+	return status;
+}
+
+static inline u8 dlm_get_lock_cookie_node(u64 cookie)
+{
+	u8 ret;
+	cookie >>= 56;
+	ret = (u8)(cookie & 0xffULL);
+	return ret;
+}
+
+static inline unsigned long long dlm_get_lock_cookie_seq(u64 cookie)
+{
+	unsigned long long ret;
+	ret = ((unsigned long long)cookie) & 0x00ffffffffffffffULL;
+	return ret;
+}
+
+struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
+			       struct dlm_lockstatus *lksb);
+void dlm_lock_get(struct dlm_lock *lock);
+void dlm_lock_put(struct dlm_lock *lock);
+
+void dlm_lock_attach_lockres(struct dlm_lock *lock,
+			     struct dlm_lock_resource *res);
+
+int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data);
+int dlm_convert_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			     void **ret_data);
+int dlm_proxy_ast_handler(struct o2net_msg *msg, u32 len, void *data,
+			  void **ret_data);
+
+void dlm_revert_pending_convert(struct dlm_lock_resource *res,
+				struct dlm_lock *lock);
+void dlm_revert_pending_lock(struct dlm_lock_resource *res,
+			     struct dlm_lock *lock);
+
+int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data);
+void dlm_commit_pending_cancel(struct dlm_lock_resource *res,
+			       struct dlm_lock *lock);
+void dlm_commit_pending_unlock(struct dlm_lock_resource *res,
+			       struct dlm_lock *lock);
+
+int dlm_launch_thread(struct dlm_ctxt *dlm);
+void dlm_complete_thread(struct dlm_ctxt *dlm);
+int dlm_launch_recovery_thread(struct dlm_ctxt *dlm);
+void dlm_complete_recovery_thread(struct dlm_ctxt *dlm);
+void dlm_wait_for_recovery(struct dlm_ctxt *dlm);
+void dlm_kick_recovery_thread(struct dlm_ctxt *dlm);
+int dlm_is_node_dead(struct dlm_ctxt *dlm, u8 node);
+void dlm_wait_for_node_death(struct dlm_ctxt *dlm, u8 node, int timeout);
+void dlm_wait_for_node_recovery(struct dlm_ctxt *dlm, u8 node, int timeout);
+
+void dlm_put(struct dlm_ctxt *dlm);
+struct dlm_ctxt *dlm_grab(struct dlm_ctxt *dlm);
+int dlm_domain_fully_joined(struct dlm_ctxt *dlm);
+
+void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+			      struct dlm_lock_resource *res);
+void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+			    struct dlm_lock_resource *res);
+static inline void dlm_lockres_get(struct dlm_lock_resource *res)
+{
+	/* This is called on every lookup, so it might be worth
+	 * inlining. */
+	kref_get(&res->refs);
+}
+void dlm_lockres_put(struct dlm_lock_resource *res);
+void __dlm_unhash_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res);
+void __dlm_insert_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res);
+struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
+						     const char *name,
+						     unsigned int len,
+						     unsigned int hash);
+struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
+						const char *name,
+						unsigned int len,
+						unsigned int hash);
+struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
+					      const char *name,
+					      unsigned int len);
+
+int dlm_is_host_down(int errno);
+
+struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
+						 const char *lockid,
+						 int namelen,
+						 int flags);
+struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
+					  const char *name,
+					  unsigned int namelen);
+
+void dlm_lockres_set_refmap_bit(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res, int bit);
+void dlm_lockres_clear_refmap_bit(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res, int bit);
+
+void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
+				   struct dlm_lock_resource *res);
+void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
+				   struct dlm_lock_resource *res);
+
+void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res);
+
+void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
+void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
+void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
+void dlm_do_local_ast(struct dlm_ctxt *dlm,
+		      struct dlm_lock_resource *res,
+		      struct dlm_lock *lock);
+int dlm_do_remote_ast(struct dlm_ctxt *dlm,
+		      struct dlm_lock_resource *res,
+		      struct dlm_lock *lock);
+void dlm_do_local_bast(struct dlm_ctxt *dlm,
+		       struct dlm_lock_resource *res,
+		       struct dlm_lock *lock,
+		       int blocked_type);
+int dlm_send_proxy_ast_msg(struct dlm_ctxt *dlm,
+			   struct dlm_lock_resource *res,
+			   struct dlm_lock *lock,
+			   int msg_type,
+			   int blocked_type, int flags);
+static inline int dlm_send_proxy_bast(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res,
+				      struct dlm_lock *lock,
+				      int blocked_type)
+{
+	return dlm_send_proxy_ast_msg(dlm, res, lock, DLM_BAST,
+				      blocked_type, 0);
+}
+
+static inline int dlm_send_proxy_ast(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     struct dlm_lock *lock,
+				     int flags)
+{
+	return dlm_send_proxy_ast_msg(dlm, res, lock, DLM_AST,
+				      0, flags);
+}
+
+void dlm_print_one_lock_resource(struct dlm_lock_resource *res);
+void __dlm_print_one_lock_resource(struct dlm_lock_resource *res);
+
+void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res);
+void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res);
+
+
+void dlm_hb_node_down_cb(struct o2nm_node *node, int idx, void *data);
+void dlm_hb_node_up_cb(struct o2nm_node *node, int idx, void *data);
+
+int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res);
+int dlm_finish_migration(struct dlm_ctxt *dlm,
+			 struct dlm_lock_resource *res,
+			 u8 old_master);
+void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
+			     struct dlm_lock_resource *res);
+void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res);
+
+int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data);
+int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data);
+void dlm_assert_master_post_handler(int status, void *data, void *ret_data);
+int dlm_deref_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data);
+int dlm_deref_lockres_done_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data);
+int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
+				void **ret_data);
+int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data);
+int dlm_master_requery_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data);
+int dlm_request_all_locks_handler(struct o2net_msg *msg, u32 len, void *data,
+				  void **ret_data);
+int dlm_reco_data_done_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data);
+int dlm_begin_reco_handler(struct o2net_msg *msg, u32 len, void *data,
+			   void **ret_data);
+int dlm_finalize_reco_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data);
+int dlm_do_master_requery(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			  u8 nodenum, u8 *real_master);
+
+void __dlm_do_purge_lockres(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res);
+
+int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
+			       struct dlm_lock_resource *res,
+			       int ignore_higher,
+			       u8 request_from,
+			       u32 flags);
+
+
+int dlm_send_one_lockres(struct dlm_ctxt *dlm,
+			 struct dlm_lock_resource *res,
+			 struct dlm_migratable_lockres *mres,
+			 u8 send_to,
+			 u8 flags);
+void dlm_move_lockres_to_recovery_list(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res);
+
+/* will exit holding res->spinlock, but may drop in function */
+void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags);
+
+/* will exit holding res->spinlock, but may drop in function */
+static inline void __dlm_wait_on_lockres(struct dlm_lock_resource *res)
+{
+	__dlm_wait_on_lockres_flags(res, (DLM_LOCK_RES_IN_PROGRESS|
+				    	  DLM_LOCK_RES_RECOVERING|
+					  DLM_LOCK_RES_RECOVERY_WAITING|
+					  DLM_LOCK_RES_MIGRATING));
+}
+
+void __dlm_unlink_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle);
+void __dlm_insert_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle);
+
+/* create/destroy slab caches */
+int dlm_init_master_caches(void);
+void dlm_destroy_master_caches(void);
+
+int dlm_init_lock_cache(void);
+void dlm_destroy_lock_cache(void);
+
+int dlm_init_mle_cache(void);
+void dlm_destroy_mle_cache(void);
+
+void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up);
+int dlm_drop_lockres_ref(struct dlm_ctxt *dlm,
+			 struct dlm_lock_resource *res);
+void dlm_clean_master_list(struct dlm_ctxt *dlm,
+			   u8 dead_node);
+void dlm_force_free_mles(struct dlm_ctxt *dlm);
+int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock);
+int __dlm_lockres_has_locks(struct dlm_lock_resource *res);
+int __dlm_lockres_unused(struct dlm_lock_resource *res);
+
+static inline const char * dlm_lock_mode_name(int mode)
+{
+	switch (mode) {
+		case LKM_EXMODE:
+			return "EX";
+		case LKM_PRMODE:
+			return "PR";
+		case LKM_NLMODE:
+			return "NL";
+	}
+	return "UNKNOWN";
+}
+
+
+static inline int dlm_lock_compatible(int existing, int request)
+{
+	/* NO_LOCK compatible with all */
+	if (request == LKM_NLMODE ||
+	    existing == LKM_NLMODE)
+		return 1;
+
+	/* EX incompatible with all non-NO_LOCK */
+	if (request == LKM_EXMODE)
+		return 0;
+
+	/* request must be PR, which is compatible with PR */
+	if (existing == LKM_PRMODE)
+		return 1;
+
+	return 0;
+}
+
+static inline int dlm_lock_on_list(struct list_head *head,
+				   struct dlm_lock *lock)
+{
+	struct dlm_lock *tmplock;
+
+	list_for_each_entry(tmplock, head, list) {
+		if (tmplock == lock)
+			return 1;
+	}
+	return 0;
+}
+
+
+static inline enum dlm_status dlm_err_to_dlm_status(int err)
+{
+	enum dlm_status ret;
+	if (err == -ENOMEM)
+		ret = DLM_SYSERR;
+	else if (err == -ETIMEDOUT || o2net_link_down(err, NULL))
+		ret = DLM_NOLOCKMGR;
+	else if (err == -EINVAL)
+		ret = DLM_BADPARAM;
+	else if (err == -ENAMETOOLONG)
+		ret = DLM_IVBUFLEN;
+	else
+		ret = DLM_BADARGS;
+	return ret;
+}
+
+
+static inline void dlm_node_iter_init(unsigned long *map,
+				      struct dlm_node_iter *iter)
+{
+	memcpy(iter->node_map, map, sizeof(iter->node_map));
+	iter->curnode = -1;
+}
+
+static inline int dlm_node_iter_next(struct dlm_node_iter *iter)
+{
+	int bit;
+	bit = find_next_bit(iter->node_map, O2NM_MAX_NODES, iter->curnode+1);
+	if (bit >= O2NM_MAX_NODES) {
+		iter->curnode = O2NM_MAX_NODES;
+		return -ENOENT;
+	}
+	iter->curnode = bit;
+	return bit;
+}
+
+static inline void dlm_set_lockres_owner(struct dlm_ctxt *dlm,
+					 struct dlm_lock_resource *res,
+					 u8 owner)
+{
+	assert_spin_locked(&res->spinlock);
+
+	res->owner = owner;
+}
+
+static inline void dlm_change_lockres_owner(struct dlm_ctxt *dlm,
+					    struct dlm_lock_resource *res,
+					    u8 owner)
+{
+	assert_spin_locked(&res->spinlock);
+
+	if (owner != res->owner)
+		dlm_set_lockres_owner(dlm, res, owner);
+}
+
+#endif /* DLMCOMMON_H */
diff --git a/fs/ocfs2/dlm/dlmconvert.c b/fs/ocfs2/dlm/dlmconvert.c
new file mode 100644
index 000000000..450d46eef
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmconvert.c
@@ -0,0 +1,555 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmconvert.c
+ *
+ * underlying calls for lock conversion
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/spinlock.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+
+#include "dlmconvert.h"
+
+#define MLOG_MASK_PREFIX ML_DLM
+#include "../cluster/masklog.h"
+
+/* NOTE: __dlmconvert_master is the only function in here that
+ * needs a spinlock held on entry (res->spinlock) and it is the
+ * only one that holds a lock on exit (res->spinlock).
+ * All other functions in here need no locks and drop all of
+ * the locks that they acquire. */
+static enum dlm_status __dlmconvert_master(struct dlm_ctxt *dlm,
+					   struct dlm_lock_resource *res,
+					   struct dlm_lock *lock, int flags,
+					   int type, int *call_ast,
+					   int *kick_thread);
+static enum dlm_status dlm_send_remote_convert_request(struct dlm_ctxt *dlm,
+					   struct dlm_lock_resource *res,
+					   struct dlm_lock *lock, int flags, int type);
+
+/*
+ * this is only called directly by dlmlock(), and only when the
+ * local node is the owner of the lockres
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock
+ *   held on exit:  none
+ * returns: see __dlmconvert_master
+ */
+enum dlm_status dlmconvert_master(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res,
+				  struct dlm_lock *lock, int flags, int type)
+{
+	int call_ast = 0, kick_thread = 0;
+	enum dlm_status status;
+
+	spin_lock(&res->spinlock);
+	/* we are not in a network handler, this is fine */
+	__dlm_wait_on_lockres(res);
+	__dlm_lockres_reserve_ast(res);
+	res->state |= DLM_LOCK_RES_IN_PROGRESS;
+
+	status = __dlmconvert_master(dlm, res, lock, flags, type,
+				     &call_ast, &kick_thread);
+
+	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+	if (status != DLM_NORMAL && status != DLM_NOTQUEUED)
+		dlm_error(status);
+
+	/* either queue the ast or release it */
+	if (call_ast)
+		dlm_queue_ast(dlm, lock);
+	else
+		dlm_lockres_release_ast(dlm, res);
+
+	if (kick_thread)
+		dlm_kick_thread(dlm, res);
+
+	return status;
+}
+
+/* performs lock conversion at the lockres master site
+ * locking:
+ *   caller needs:  res->spinlock
+ *   taken:         takes and drops lock->spinlock
+ *   held on exit:  res->spinlock
+ * returns: DLM_NORMAL, DLM_NOTQUEUED, DLM_DENIED
+ *   call_ast: whether ast should be called for this lock
+ *   kick_thread: whether dlm_kick_thread should be called
+ */
+static enum dlm_status __dlmconvert_master(struct dlm_ctxt *dlm,
+					   struct dlm_lock_resource *res,
+					   struct dlm_lock *lock, int flags,
+					   int type, int *call_ast,
+					   int *kick_thread)
+{
+	enum dlm_status status = DLM_NORMAL;
+	struct dlm_lock *tmplock=NULL;
+
+	assert_spin_locked(&res->spinlock);
+
+	mlog(0, "type=%d, convert_type=%d, new convert_type=%d\n",
+	     lock->ml.type, lock->ml.convert_type, type);
+
+	spin_lock(&lock->spinlock);
+
+	/* already converting? */
+	if (lock->ml.convert_type != LKM_IVMODE) {
+		mlog(ML_ERROR, "attempted to convert a lock with a lock "
+		     "conversion pending\n");
+		status = DLM_DENIED;
+		goto unlock_exit;
+	}
+
+	/* must be on grant queue to convert */
+	if (!dlm_lock_on_list(&res->granted, lock)) {
+		mlog(ML_ERROR, "attempted to convert a lock not on grant "
+		     "queue\n");
+		status = DLM_DENIED;
+		goto unlock_exit;
+	}
+
+	if (flags & LKM_VALBLK) {
+		switch (lock->ml.type) {
+			case LKM_EXMODE:
+				/* EX + LKM_VALBLK + convert == set lvb */
+				mlog(0, "will set lvb: converting %s->%s\n",
+				     dlm_lock_mode_name(lock->ml.type),
+				     dlm_lock_mode_name(type));
+				lock->lksb->flags |= DLM_LKSB_PUT_LVB;
+				break;
+			case LKM_PRMODE:
+			case LKM_NLMODE:
+				/* refetch if new level is not NL */
+				if (type > LKM_NLMODE) {
+					mlog(0, "will fetch new value into "
+					     "lvb: converting %s->%s\n",
+					     dlm_lock_mode_name(lock->ml.type),
+					     dlm_lock_mode_name(type));
+					lock->lksb->flags |= DLM_LKSB_GET_LVB;
+				} else {
+					mlog(0, "will NOT fetch new value "
+					     "into lvb: converting %s->%s\n",
+					     dlm_lock_mode_name(lock->ml.type),
+					     dlm_lock_mode_name(type));
+					flags &= ~(LKM_VALBLK);
+				}
+				break;
+		}
+	}
+
+
+	/* in-place downconvert? */
+	if (type <= lock->ml.type)
+		goto grant;
+
+	/* upconvert from here on */
+	status = DLM_NORMAL;
+	list_for_each_entry(tmplock, &res->granted, list) {
+		if (tmplock == lock)
+			continue;
+		if (!dlm_lock_compatible(tmplock->ml.type, type))
+			goto switch_queues;
+	}
+
+	list_for_each_entry(tmplock, &res->converting, list) {
+		if (!dlm_lock_compatible(tmplock->ml.type, type))
+			goto switch_queues;
+		/* existing conversion requests take precedence */
+		if (!dlm_lock_compatible(tmplock->ml.convert_type, type))
+			goto switch_queues;
+	}
+
+	/* fall thru to grant */
+
+grant:
+	mlog(0, "res %.*s, granting %s lock\n", res->lockname.len,
+	     res->lockname.name, dlm_lock_mode_name(type));
+	/* immediately grant the new lock type */
+	lock->lksb->status = DLM_NORMAL;
+	if (lock->ml.node == dlm->node_num)
+		mlog(0, "doing in-place convert for nonlocal lock\n");
+	lock->ml.type = type;
+	if (lock->lksb->flags & DLM_LKSB_PUT_LVB)
+		memcpy(res->lvb, lock->lksb->lvb, DLM_LVB_LEN);
+
+	/*
+	 * Move the lock to the tail because it may be the only lock which has
+	 * an invalid lvb.
+	 */
+	list_move_tail(&lock->list, &res->granted);
+
+	status = DLM_NORMAL;
+	*call_ast = 1;
+	goto unlock_exit;
+
+switch_queues:
+	if (flags & LKM_NOQUEUE) {
+		mlog(0, "failed to convert NOQUEUE lock %.*s from "
+		     "%d to %d...\n", res->lockname.len, res->lockname.name,
+		     lock->ml.type, type);
+		status = DLM_NOTQUEUED;
+		goto unlock_exit;
+	}
+	mlog(0, "res %.*s, queueing...\n", res->lockname.len,
+	     res->lockname.name);
+
+	lock->ml.convert_type = type;
+	/* do not alter lock refcount.  switching lists. */
+	list_move_tail(&lock->list, &res->converting);
+
+unlock_exit:
+	spin_unlock(&lock->spinlock);
+	if (status == DLM_DENIED) {
+		__dlm_print_one_lock_resource(res);
+	}
+	if (status == DLM_NORMAL)
+		*kick_thread = 1;
+	return status;
+}
+
+void dlm_revert_pending_convert(struct dlm_lock_resource *res,
+				struct dlm_lock *lock)
+{
+	/* do not alter lock refcount.  switching lists. */
+	list_move_tail(&lock->list, &res->granted);
+	lock->ml.convert_type = LKM_IVMODE;
+	lock->lksb->flags &= ~(DLM_LKSB_GET_LVB|DLM_LKSB_PUT_LVB);
+}
+
+/* messages the master site to do lock conversion
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock, uses DLM_LOCK_RES_IN_PROGRESS
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_RECOVERING, status from remote node
+ */
+enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res,
+				  struct dlm_lock *lock, int flags, int type)
+{
+	enum dlm_status status;
+
+	mlog(0, "type=%d, convert_type=%d, busy=%d\n", lock->ml.type,
+	     lock->ml.convert_type, res->state & DLM_LOCK_RES_IN_PROGRESS);
+
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_RECOVERING) {
+		mlog(0, "bailing out early since res is RECOVERING "
+		     "on secondary queue\n");
+		/* __dlm_print_one_lock_resource(res); */
+		status = DLM_RECOVERING;
+		goto bail;
+	}
+	/* will exit this call with spinlock held */
+	__dlm_wait_on_lockres(res);
+
+	if (lock->ml.convert_type != LKM_IVMODE) {
+		__dlm_print_one_lock_resource(res);
+		mlog(ML_ERROR, "converting a remote lock that is already "
+		     "converting! (cookie=%u:%llu, conv=%d)\n",
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     lock->ml.convert_type);
+		status = DLM_DENIED;
+		goto bail;
+	}
+
+	if (lock->ml.type == type && lock->ml.convert_type == LKM_IVMODE) {
+		mlog(0, "last convert request returned DLM_RECOVERING, but "
+		     "owner has already queued and sent ast to me. res %.*s, "
+		     "(cookie=%u:%llu, type=%d, conv=%d)\n",
+		     res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     lock->ml.type, lock->ml.convert_type);
+		status = DLM_NORMAL;
+		goto bail;
+	}
+
+	res->state |= DLM_LOCK_RES_IN_PROGRESS;
+	/* move lock to local convert queue */
+	/* do not alter lock refcount.  switching lists. */
+	list_move_tail(&lock->list, &res->converting);
+	lock->convert_pending = 1;
+	lock->ml.convert_type = type;
+
+	if (flags & LKM_VALBLK) {
+		if (lock->ml.type == LKM_EXMODE) {
+			flags |= LKM_PUT_LVB;
+			lock->lksb->flags |= DLM_LKSB_PUT_LVB;
+		} else {
+			if (lock->ml.convert_type == LKM_NLMODE)
+				flags &= ~LKM_VALBLK;
+			else {
+				flags |= LKM_GET_LVB;
+				lock->lksb->flags |= DLM_LKSB_GET_LVB;
+			}
+		}
+	}
+	spin_unlock(&res->spinlock);
+
+	/* no locks held here.
+	 * need to wait for a reply as to whether it got queued or not. */
+	status = dlm_send_remote_convert_request(dlm, res, lock, flags, type);
+
+	spin_lock(&res->spinlock);
+	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+	/* if it failed, move it back to granted queue.
+	 * if master returns DLM_NORMAL and then down before sending ast,
+	 * it may have already been moved to granted queue, reset to
+	 * DLM_RECOVERING and retry convert */
+	if (status != DLM_NORMAL) {
+		if (status != DLM_NOTQUEUED)
+			dlm_error(status);
+		dlm_revert_pending_convert(res, lock);
+	} else if (!lock->convert_pending) {
+		mlog(0, "%s: res %.*s, owner died and lock has been moved back "
+				"to granted list, retry convert.\n",
+				dlm->name, res->lockname.len, res->lockname.name);
+		status = DLM_RECOVERING;
+	}
+
+	lock->convert_pending = 0;
+bail:
+	spin_unlock(&res->spinlock);
+
+	/* TODO: should this be a wake_one? */
+	/* wake up any IN_PROGRESS waiters */
+	wake_up(&res->wq);
+
+	return status;
+}
+
+/* sends DLM_CONVERT_LOCK_MSG to master site
+ * locking:
+ *   caller needs:  none
+ *   taken:         none
+ *   held on exit:  none
+ * returns: DLM_NOLOCKMGR, status from remote node
+ */
+static enum dlm_status dlm_send_remote_convert_request(struct dlm_ctxt *dlm,
+					   struct dlm_lock_resource *res,
+					   struct dlm_lock *lock, int flags, int type)
+{
+	struct dlm_convert_lock convert;
+	int tmpret;
+	enum dlm_status ret;
+	int status = 0;
+	struct kvec vec[2];
+	size_t veclen = 1;
+
+	mlog(0, "%.*s\n", res->lockname.len, res->lockname.name);
+
+	memset(&convert, 0, sizeof(struct dlm_convert_lock));
+	convert.node_idx = dlm->node_num;
+	convert.requested_type = type;
+	convert.cookie = lock->ml.cookie;
+	convert.namelen = res->lockname.len;
+	convert.flags = cpu_to_be32(flags);
+	memcpy(convert.name, res->lockname.name, convert.namelen);
+
+	vec[0].iov_len = sizeof(struct dlm_convert_lock);
+	vec[0].iov_base = &convert;
+
+	if (flags & LKM_PUT_LVB) {
+		/* extra data to send if we are updating lvb */
+		vec[1].iov_len = DLM_LVB_LEN;
+		vec[1].iov_base = lock->lksb->lvb;
+		veclen++;
+	}
+
+	tmpret = o2net_send_message_vec(DLM_CONVERT_LOCK_MSG, dlm->key,
+					vec, veclen, res->owner, &status);
+	if (tmpret >= 0) {
+		// successfully sent and received
+		ret = status;  // this is already a dlm_status
+		if (ret == DLM_RECOVERING) {
+			mlog(0, "node %u returned DLM_RECOVERING from convert "
+			     "message!\n", res->owner);
+		} else if (ret == DLM_MIGRATING) {
+			mlog(0, "node %u returned DLM_MIGRATING from convert "
+			     "message!\n", res->owner);
+		} else if (ret == DLM_FORWARD) {
+			mlog(0, "node %u returned DLM_FORWARD from convert "
+			     "message!\n", res->owner);
+		} else if (ret != DLM_NORMAL && ret != DLM_NOTQUEUED)
+			dlm_error(ret);
+	} else {
+		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
+		     "node %u\n", tmpret, DLM_CONVERT_LOCK_MSG, dlm->key,
+		     res->owner);
+		if (dlm_is_host_down(tmpret)) {
+			/* instead of logging the same network error over
+			 * and over, sleep here and wait for the heartbeat
+			 * to notice the node is dead.  times out after 5s. */
+			dlm_wait_for_node_death(dlm, res->owner,
+						DLM_NODE_DEATH_WAIT_MAX);
+			ret = DLM_RECOVERING;
+			mlog(0, "node %u died so returning DLM_RECOVERING "
+			     "from convert message!\n", res->owner);
+		} else {
+			ret = dlm_err_to_dlm_status(tmpret);
+		}
+	}
+
+	return ret;
+}
+
+/* handler for DLM_CONVERT_LOCK_MSG on master site
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drop res->spinlock
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_IVLOCKID, DLM_BADARGS,
+ *          status from __dlmconvert_master
+ */
+int dlm_convert_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			     void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_convert_lock *cnv = (struct dlm_convert_lock *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_lock *lock = NULL;
+	struct dlm_lock *tmp_lock;
+	struct dlm_lockstatus *lksb;
+	enum dlm_status status = DLM_NORMAL;
+	u32 flags;
+	int call_ast = 0, kick_thread = 0, ast_reserved = 0, wake = 0;
+
+	if (!dlm_grab(dlm)) {
+		dlm_error(DLM_REJECTED);
+		return DLM_REJECTED;
+	}
+
+	mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
+			"Domain %s not fully joined!\n", dlm->name);
+
+	if (cnv->namelen > DLM_LOCKID_NAME_MAX) {
+		status = DLM_IVBUFLEN;
+		dlm_error(status);
+		goto leave;
+	}
+
+	flags = be32_to_cpu(cnv->flags);
+
+	if ((flags & (LKM_PUT_LVB|LKM_GET_LVB)) ==
+	     (LKM_PUT_LVB|LKM_GET_LVB)) {
+		mlog(ML_ERROR, "both PUT and GET lvb specified\n");
+		status = DLM_BADARGS;
+		goto leave;
+	}
+
+	mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" :
+	     (flags & LKM_GET_LVB ? "get lvb" : "none"));
+
+	status = DLM_IVLOCKID;
+	res = dlm_lookup_lockres(dlm, cnv->name, cnv->namelen);
+	if (!res) {
+		dlm_error(status);
+		goto leave;
+	}
+
+	spin_lock(&res->spinlock);
+	status = __dlm_lockres_state_to_status(res);
+	if (status != DLM_NORMAL) {
+		spin_unlock(&res->spinlock);
+		dlm_error(status);
+		goto leave;
+	}
+	list_for_each_entry(tmp_lock, &res->granted, list) {
+		if (tmp_lock->ml.cookie == cnv->cookie &&
+		    tmp_lock->ml.node == cnv->node_idx) {
+			lock = tmp_lock;
+			dlm_lock_get(lock);
+			break;
+		}
+	}
+	spin_unlock(&res->spinlock);
+	if (!lock) {
+		status = DLM_IVLOCKID;
+		mlog(ML_ERROR, "did not find lock to convert on grant queue! "
+			       "cookie=%u:%llu\n",
+		     dlm_get_lock_cookie_node(be64_to_cpu(cnv->cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(cnv->cookie)));
+		dlm_print_one_lock_resource(res);
+		goto leave;
+	}
+
+	/* found the lock */
+	lksb = lock->lksb;
+
+	/* see if caller needed to get/put lvb */
+	if (flags & LKM_PUT_LVB) {
+		BUG_ON(lksb->flags & (DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB));
+		lksb->flags |= DLM_LKSB_PUT_LVB;
+		memcpy(&lksb->lvb[0], &cnv->lvb[0], DLM_LVB_LEN);
+	} else if (flags & LKM_GET_LVB) {
+		BUG_ON(lksb->flags & (DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB));
+		lksb->flags |= DLM_LKSB_GET_LVB;
+	}
+
+	spin_lock(&res->spinlock);
+	status = __dlm_lockres_state_to_status(res);
+	if (status == DLM_NORMAL) {
+		__dlm_lockres_reserve_ast(res);
+		ast_reserved = 1;
+		res->state |= DLM_LOCK_RES_IN_PROGRESS;
+		status = __dlmconvert_master(dlm, res, lock, flags,
+					     cnv->requested_type,
+					     &call_ast, &kick_thread);
+		res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+		wake = 1;
+	}
+	spin_unlock(&res->spinlock);
+	if (wake)
+		wake_up(&res->wq);
+
+	if (status != DLM_NORMAL) {
+		if (status != DLM_NOTQUEUED)
+			dlm_error(status);
+		lksb->flags &= ~(DLM_LKSB_GET_LVB|DLM_LKSB_PUT_LVB);
+	}
+
+leave:
+	if (lock)
+		dlm_lock_put(lock);
+
+	/* either queue the ast or release it, if reserved */
+	if (call_ast)
+		dlm_queue_ast(dlm, lock);
+	else if (ast_reserved)
+		dlm_lockres_release_ast(dlm, res);
+
+	if (kick_thread)
+		dlm_kick_thread(dlm, res);
+
+	if (res)
+		dlm_lockres_put(res);
+
+	dlm_put(dlm);
+
+	return status;
+}
diff --git a/fs/ocfs2/dlm/dlmconvert.h b/fs/ocfs2/dlm/dlmconvert.h
new file mode 100644
index 000000000..1f3717165
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmconvert.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmconvert.h
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+#ifndef DLMCONVERT_H
+#define DLMCONVERT_H
+
+enum dlm_status dlmconvert_master(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res,
+				  struct dlm_lock *lock, int flags, int type);
+enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res,
+				  struct dlm_lock *lock, int flags, int type);
+
+#endif
diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
new file mode 100644
index 000000000..be5e9ed7d
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -0,0 +1,894 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmdebug.c
+ *
+ * debug functionality for the dlm
+ *
+ * Copyright (C) 2004, 2008 Oracle.  All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/sysctl.h>
+#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <linux/export.h>
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+#include "dlmdebug.h"
+
+#define MLOG_MASK_PREFIX ML_DLM
+#include "../cluster/masklog.h"
+
+static int stringify_lockname(const char *lockname, int locklen, char *buf,
+			      int len);
+
+void dlm_print_one_lock_resource(struct dlm_lock_resource *res)
+{
+	spin_lock(&res->spinlock);
+	__dlm_print_one_lock_resource(res);
+	spin_unlock(&res->spinlock);
+}
+
+static void dlm_print_lockres_refmap(struct dlm_lock_resource *res)
+{
+	int bit;
+	assert_spin_locked(&res->spinlock);
+
+	printk("  refmap nodes: [ ");
+	bit = 0;
+	while (1) {
+		bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
+		if (bit >= O2NM_MAX_NODES)
+			break;
+		printk("%u ", bit);
+		bit++;
+	}
+	printk("], inflight=%u\n", res->inflight_locks);
+}
+
+static void __dlm_print_lock(struct dlm_lock *lock)
+{
+	spin_lock(&lock->spinlock);
+
+	printk("    type=%d, conv=%d, node=%u, cookie=%u:%llu, "
+	       "ref=%u, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c), "
+	       "pending=(conv=%c,lock=%c,cancel=%c,unlock=%c)\n",
+	       lock->ml.type, lock->ml.convert_type, lock->ml.node,
+	       dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	       dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+	       kref_read(&lock->lock_refs),
+	       (list_empty(&lock->ast_list) ? 'y' : 'n'),
+	       (lock->ast_pending ? 'y' : 'n'),
+	       (list_empty(&lock->bast_list) ? 'y' : 'n'),
+	       (lock->bast_pending ? 'y' : 'n'),
+	       (lock->convert_pending ? 'y' : 'n'),
+	       (lock->lock_pending ? 'y' : 'n'),
+	       (lock->cancel_pending ? 'y' : 'n'),
+	       (lock->unlock_pending ? 'y' : 'n'));
+
+	spin_unlock(&lock->spinlock);
+}
+
+void __dlm_print_one_lock_resource(struct dlm_lock_resource *res)
+{
+	struct dlm_lock *lock;
+	char buf[DLM_LOCKID_NAME_MAX];
+
+	assert_spin_locked(&res->spinlock);
+
+	stringify_lockname(res->lockname.name, res->lockname.len,
+			   buf, sizeof(buf));
+	printk("lockres: %s, owner=%u, state=%u\n",
+	       buf, res->owner, res->state);
+	printk("  last used: %lu, refcnt: %u, on purge list: %s\n",
+	       res->last_used, kref_read(&res->refs),
+	       list_empty(&res->purge) ? "no" : "yes");
+	printk("  on dirty list: %s, on reco list: %s, "
+	       "migrating pending: %s\n",
+	       list_empty(&res->dirty) ? "no" : "yes",
+	       list_empty(&res->recovering) ? "no" : "yes",
+	       res->migration_pending ? "yes" : "no");
+	printk("  inflight locks: %d, asts reserved: %d\n",
+	       res->inflight_locks, atomic_read(&res->asts_reserved));
+	dlm_print_lockres_refmap(res);
+	printk("  granted queue:\n");
+	list_for_each_entry(lock, &res->granted, list) {
+		__dlm_print_lock(lock);
+	}
+	printk("  converting queue:\n");
+	list_for_each_entry(lock, &res->converting, list) {
+		__dlm_print_lock(lock);
+	}
+	printk("  blocked queue:\n");
+	list_for_each_entry(lock, &res->blocked, list) {
+		__dlm_print_lock(lock);
+	}
+}
+
+void dlm_print_one_lock(struct dlm_lock *lockid)
+{
+	dlm_print_one_lock_resource(lockid->lockres);
+}
+EXPORT_SYMBOL_GPL(dlm_print_one_lock);
+
+static const char *dlm_errnames[] = {
+	[DLM_NORMAL] =			"DLM_NORMAL",
+	[DLM_GRANTED] =			"DLM_GRANTED",
+	[DLM_DENIED] =			"DLM_DENIED",
+	[DLM_DENIED_NOLOCKS] =		"DLM_DENIED_NOLOCKS",
+	[DLM_WORKING] =			"DLM_WORKING",
+	[DLM_BLOCKED] =			"DLM_BLOCKED",
+	[DLM_BLOCKED_ORPHAN] =		"DLM_BLOCKED_ORPHAN",
+	[DLM_DENIED_GRACE_PERIOD] =	"DLM_DENIED_GRACE_PERIOD",
+	[DLM_SYSERR] =			"DLM_SYSERR",
+	[DLM_NOSUPPORT] =		"DLM_NOSUPPORT",
+	[DLM_CANCELGRANT] =		"DLM_CANCELGRANT",
+	[DLM_IVLOCKID] =		"DLM_IVLOCKID",
+	[DLM_SYNC] =			"DLM_SYNC",
+	[DLM_BADTYPE] =			"DLM_BADTYPE",
+	[DLM_BADRESOURCE] =		"DLM_BADRESOURCE",
+	[DLM_MAXHANDLES] =		"DLM_MAXHANDLES",
+	[DLM_NOCLINFO] =		"DLM_NOCLINFO",
+	[DLM_NOLOCKMGR] =		"DLM_NOLOCKMGR",
+	[DLM_NOPURGED] =		"DLM_NOPURGED",
+	[DLM_BADARGS] =			"DLM_BADARGS",
+	[DLM_VOID] =			"DLM_VOID",
+	[DLM_NOTQUEUED] =		"DLM_NOTQUEUED",
+	[DLM_IVBUFLEN] =		"DLM_IVBUFLEN",
+	[DLM_CVTUNGRANT] =		"DLM_CVTUNGRANT",
+	[DLM_BADPARAM] =		"DLM_BADPARAM",
+	[DLM_VALNOTVALID] =		"DLM_VALNOTVALID",
+	[DLM_REJECTED] =		"DLM_REJECTED",
+	[DLM_ABORT] =			"DLM_ABORT",
+	[DLM_CANCEL] =			"DLM_CANCEL",
+	[DLM_IVRESHANDLE] =		"DLM_IVRESHANDLE",
+	[DLM_DEADLOCK] =		"DLM_DEADLOCK",
+	[DLM_DENIED_NOASTS] =		"DLM_DENIED_NOASTS",
+	[DLM_FORWARD] =			"DLM_FORWARD",
+	[DLM_TIMEOUT] =			"DLM_TIMEOUT",
+	[DLM_IVGROUPID] =		"DLM_IVGROUPID",
+	[DLM_VERS_CONFLICT] =		"DLM_VERS_CONFLICT",
+	[DLM_BAD_DEVICE_PATH] =		"DLM_BAD_DEVICE_PATH",
+	[DLM_NO_DEVICE_PERMISSION] =	"DLM_NO_DEVICE_PERMISSION",
+	[DLM_NO_CONTROL_DEVICE ] =	"DLM_NO_CONTROL_DEVICE ",
+	[DLM_RECOVERING] =		"DLM_RECOVERING",
+	[DLM_MIGRATING] =		"DLM_MIGRATING",
+	[DLM_MAXSTATS] =		"DLM_MAXSTATS",
+};
+
+static const char *dlm_errmsgs[] = {
+	[DLM_NORMAL] = 			"request in progress",
+	[DLM_GRANTED] = 		"request granted",
+	[DLM_DENIED] = 			"request denied",
+	[DLM_DENIED_NOLOCKS] = 		"request denied, out of system resources",
+	[DLM_WORKING] = 		"async request in progress",
+	[DLM_BLOCKED] = 		"lock request blocked",
+	[DLM_BLOCKED_ORPHAN] = 		"lock request blocked by a orphan lock",
+	[DLM_DENIED_GRACE_PERIOD] = 	"topological change in progress",
+	[DLM_SYSERR] = 			"system error",
+	[DLM_NOSUPPORT] = 		"unsupported",
+	[DLM_CANCELGRANT] = 		"can't cancel convert: already granted",
+	[DLM_IVLOCKID] = 		"bad lockid",
+	[DLM_SYNC] = 			"synchronous request granted",
+	[DLM_BADTYPE] = 		"bad resource type",
+	[DLM_BADRESOURCE] = 		"bad resource handle",
+	[DLM_MAXHANDLES] = 		"no more resource handles",
+	[DLM_NOCLINFO] = 		"can't contact cluster manager",
+	[DLM_NOLOCKMGR] = 		"can't contact lock manager",
+	[DLM_NOPURGED] = 		"can't contact purge daemon",
+	[DLM_BADARGS] = 		"bad api args",
+	[DLM_VOID] = 			"no status",
+	[DLM_NOTQUEUED] = 		"NOQUEUE was specified and request failed",
+	[DLM_IVBUFLEN] = 		"invalid resource name length",
+	[DLM_CVTUNGRANT] = 		"attempted to convert ungranted lock",
+	[DLM_BADPARAM] = 		"invalid lock mode specified",
+	[DLM_VALNOTVALID] = 		"value block has been invalidated",
+	[DLM_REJECTED] = 		"request rejected, unrecognized client",
+	[DLM_ABORT] = 			"blocked lock request cancelled",
+	[DLM_CANCEL] = 			"conversion request cancelled",
+	[DLM_IVRESHANDLE] = 		"invalid resource handle",
+	[DLM_DEADLOCK] = 		"deadlock recovery refused this request",
+	[DLM_DENIED_NOASTS] = 		"failed to allocate AST",
+	[DLM_FORWARD] = 		"request must wait for primary's response",
+	[DLM_TIMEOUT] = 		"timeout value for lock has expired",
+	[DLM_IVGROUPID] = 		"invalid group specification",
+	[DLM_VERS_CONFLICT] = 		"version conflicts prevent request handling",
+	[DLM_BAD_DEVICE_PATH] = 	"Locks device does not exist or path wrong",
+	[DLM_NO_DEVICE_PERMISSION] = 	"Client has insufficient perms for device",
+	[DLM_NO_CONTROL_DEVICE] = 	"Cannot set options on opened device ",
+	[DLM_RECOVERING] = 		"lock resource being recovered",
+	[DLM_MIGRATING] = 		"lock resource being migrated",
+	[DLM_MAXSTATS] = 		"invalid error number",
+};
+
+const char *dlm_errmsg(enum dlm_status err)
+{
+	if (err >= DLM_MAXSTATS || err < 0)
+		return dlm_errmsgs[DLM_MAXSTATS];
+	return dlm_errmsgs[err];
+}
+EXPORT_SYMBOL_GPL(dlm_errmsg);
+
+const char *dlm_errname(enum dlm_status err)
+{
+	if (err >= DLM_MAXSTATS || err < 0)
+		return dlm_errnames[DLM_MAXSTATS];
+	return dlm_errnames[err];
+}
+EXPORT_SYMBOL_GPL(dlm_errname);
+
+/* NOTE: This function converts a lockname into a string. It uses knowledge
+ * of the format of the lockname that should be outside the purview of the dlm.
+ * We are adding only to make dlm debugging slightly easier.
+ *
+ * For more on lockname formats, please refer to dlmglue.c and ocfs2_lockid.h.
+ */
+static int stringify_lockname(const char *lockname, int locklen, char *buf,
+			      int len)
+{
+	int out = 0;
+	__be64 inode_blkno_be;
+
+#define OCFS2_DENTRY_LOCK_INO_START	18
+	if (*lockname == 'N') {
+		memcpy((__be64 *)&inode_blkno_be,
+		       (char *)&lockname[OCFS2_DENTRY_LOCK_INO_START],
+		       sizeof(__be64));
+		out += scnprintf(buf + out, len - out, "%.*s%08x",
+				OCFS2_DENTRY_LOCK_INO_START - 1, lockname,
+				(unsigned int)be64_to_cpu(inode_blkno_be));
+	} else
+		out += scnprintf(buf + out, len - out, "%.*s",
+				locklen, lockname);
+	return out;
+}
+
+static int stringify_nodemap(unsigned long *nodemap, int maxnodes,
+			     char *buf, int len)
+{
+	int out = 0;
+	int i = -1;
+
+	while ((i = find_next_bit(nodemap, maxnodes, i + 1)) < maxnodes)
+		out += scnprintf(buf + out, len - out, "%d ", i);
+
+	return out;
+}
+
+static int dump_mle(struct dlm_master_list_entry *mle, char *buf, int len)
+{
+	int out = 0;
+	char *mle_type;
+
+	if (mle->type == DLM_MLE_BLOCK)
+		mle_type = "BLK";
+	else if (mle->type == DLM_MLE_MASTER)
+		mle_type = "MAS";
+	else
+		mle_type = "MIG";
+
+	out += stringify_lockname(mle->mname, mle->mnamelen, buf + out, len - out);
+	out += scnprintf(buf + out, len - out,
+			"\t%3s\tmas=%3u\tnew=%3u\tevt=%1d\tuse=%1d\tref=%3d\n",
+			mle_type, mle->master, mle->new_master,
+			!list_empty(&mle->hb_events),
+			!!mle->inuse,
+			kref_read(&mle->mle_refs));
+
+	out += scnprintf(buf + out, len - out, "Maybe=");
+	out += stringify_nodemap(mle->maybe_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	out += scnprintf(buf + out, len - out, "Vote=");
+	out += stringify_nodemap(mle->vote_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	out += scnprintf(buf + out, len - out, "Response=");
+	out += stringify_nodemap(mle->response_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	out += scnprintf(buf + out, len - out, "Node=");
+	out += stringify_nodemap(mle->node_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	out += scnprintf(buf + out, len - out, "\n");
+
+	return out;
+}
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle)
+{
+	char *buf;
+
+	buf = (char *) get_zeroed_page(GFP_ATOMIC);
+	if (buf) {
+		dump_mle(mle, buf, PAGE_SIZE - 1);
+		free_page((unsigned long)buf);
+	}
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *dlm_debugfs_root;
+
+#define DLM_DEBUGFS_DIR				"o2dlm"
+#define DLM_DEBUGFS_DLM_STATE			"dlm_state"
+#define DLM_DEBUGFS_LOCKING_STATE		"locking_state"
+#define DLM_DEBUGFS_MLE_STATE			"mle_state"
+#define DLM_DEBUGFS_PURGE_LIST			"purge_list"
+
+/* begin - utils funcs */
+static int debug_release(struct inode *inode, struct file *file)
+{
+	free_page((unsigned long)file->private_data);
+	return 0;
+}
+
+static ssize_t debug_read(struct file *file, char __user *buf,
+			  size_t nbytes, loff_t *ppos)
+{
+	return simple_read_from_buffer(buf, nbytes, ppos, file->private_data,
+				       i_size_read(file->f_mapping->host));
+}
+/* end - util funcs */
+
+/* begin - purge list funcs */
+static int debug_purgelist_print(struct dlm_ctxt *dlm, char *buf, int len)
+{
+	struct dlm_lock_resource *res;
+	int out = 0;
+	unsigned long total = 0;
+
+	out += scnprintf(buf + out, len - out,
+			"Dumping Purgelist for Domain: %s\n", dlm->name);
+
+	spin_lock(&dlm->spinlock);
+	list_for_each_entry(res, &dlm->purge_list, purge) {
+		++total;
+		if (len - out < 100)
+			continue;
+		spin_lock(&res->spinlock);
+		out += stringify_lockname(res->lockname.name,
+					  res->lockname.len,
+					  buf + out, len - out);
+		out += scnprintf(buf + out, len - out, "\t%ld\n",
+				(jiffies - res->last_used)/HZ);
+		spin_unlock(&res->spinlock);
+	}
+	spin_unlock(&dlm->spinlock);
+
+	out += scnprintf(buf + out, len - out, "Total on list: %lu\n", total);
+
+	return out;
+}
+
+static int debug_purgelist_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	char *buf = NULL;
+
+	buf = (char *) get_zeroed_page(GFP_NOFS);
+	if (!buf)
+		goto bail;
+
+	i_size_write(inode, debug_purgelist_print(dlm, buf, PAGE_SIZE - 1));
+
+	file->private_data = buf;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static const struct file_operations debug_purgelist_fops = {
+	.open =		debug_purgelist_open,
+	.release =	debug_release,
+	.read =		debug_read,
+	.llseek =	generic_file_llseek,
+};
+/* end - purge list funcs */
+
+/* begin - debug mle funcs */
+static int debug_mle_print(struct dlm_ctxt *dlm, char *buf, int len)
+{
+	struct dlm_master_list_entry *mle;
+	struct hlist_head *bucket;
+	int i, out = 0;
+	unsigned long total = 0, longest = 0, bucket_count = 0;
+
+	out += scnprintf(buf + out, len - out,
+			"Dumping MLEs for Domain: %s\n", dlm->name);
+
+	spin_lock(&dlm->master_lock);
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+		bucket = dlm_master_hash(dlm, i);
+		hlist_for_each_entry(mle, bucket, master_hash_node) {
+			++total;
+			++bucket_count;
+			if (len - out < 200)
+				continue;
+			out += dump_mle(mle, buf + out, len - out);
+		}
+		longest = max(longest, bucket_count);
+		bucket_count = 0;
+	}
+	spin_unlock(&dlm->master_lock);
+
+	out += scnprintf(buf + out, len - out,
+			"Total: %lu, Longest: %lu\n", total, longest);
+	return out;
+}
+
+static int debug_mle_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	char *buf = NULL;
+
+	buf = (char *) get_zeroed_page(GFP_NOFS);
+	if (!buf)
+		goto bail;
+
+	i_size_write(inode, debug_mle_print(dlm, buf, PAGE_SIZE - 1));
+
+	file->private_data = buf;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static const struct file_operations debug_mle_fops = {
+	.open =		debug_mle_open,
+	.release =	debug_release,
+	.read =		debug_read,
+	.llseek =	generic_file_llseek,
+};
+
+/* end - debug mle funcs */
+
+/* begin - debug lockres funcs */
+static int dump_lock(struct dlm_lock *lock, int list_type, char *buf, int len)
+{
+	int out;
+
+#define DEBUG_LOCK_VERSION	1
+	spin_lock(&lock->spinlock);
+	out = scnprintf(buf, len, "LOCK:%d,%d,%d,%d,%d,%d:%lld,%d,%d,%d,%d,%d,"
+		       "%d,%d,%d,%d\n",
+		       DEBUG_LOCK_VERSION,
+		       list_type, lock->ml.type, lock->ml.convert_type,
+		       lock->ml.node,
+		       dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		       dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		       !list_empty(&lock->ast_list),
+		       !list_empty(&lock->bast_list),
+		       lock->ast_pending, lock->bast_pending,
+		       lock->convert_pending, lock->lock_pending,
+		       lock->cancel_pending, lock->unlock_pending,
+		       kref_read(&lock->lock_refs));
+	spin_unlock(&lock->spinlock);
+
+	return out;
+}
+
+static int dump_lockres(struct dlm_lock_resource *res, char *buf, int len)
+{
+	struct dlm_lock *lock;
+	int i;
+	int out = 0;
+
+	out += scnprintf(buf + out, len - out, "NAME:");
+	out += stringify_lockname(res->lockname.name, res->lockname.len,
+				  buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+#define DEBUG_LRES_VERSION	1
+	out += scnprintf(buf + out, len - out,
+			"LRES:%d,%d,%d,%ld,%d,%d,%d,%d,%d,%d,%d\n",
+			DEBUG_LRES_VERSION,
+			res->owner, res->state, res->last_used,
+			!list_empty(&res->purge),
+			!list_empty(&res->dirty),
+			!list_empty(&res->recovering),
+			res->inflight_locks, res->migration_pending,
+			atomic_read(&res->asts_reserved),
+			kref_read(&res->refs));
+
+	/* refmap */
+	out += scnprintf(buf + out, len - out, "RMAP:");
+	out += stringify_nodemap(res->refmap, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* lvb */
+	out += scnprintf(buf + out, len - out, "LVBX:");
+	for (i = 0; i < DLM_LVB_LEN; i++)
+		out += scnprintf(buf + out, len - out,
+					"%02x", (unsigned char)res->lvb[i]);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* granted */
+	list_for_each_entry(lock, &res->granted, list)
+		out += dump_lock(lock, 0, buf + out, len - out);
+
+	/* converting */
+	list_for_each_entry(lock, &res->converting, list)
+		out += dump_lock(lock, 1, buf + out, len - out);
+
+	/* blocked */
+	list_for_each_entry(lock, &res->blocked, list)
+		out += dump_lock(lock, 2, buf + out, len - out);
+
+	out += scnprintf(buf + out, len - out, "\n");
+
+	return out;
+}
+
+static void *lockres_seq_start(struct seq_file *m, loff_t *pos)
+{
+	struct debug_lockres *dl = m->private;
+	struct dlm_ctxt *dlm = dl->dl_ctxt;
+	struct dlm_lock_resource *oldres = dl->dl_res;
+	struct dlm_lock_resource *res = NULL, *iter;
+	struct list_head *track_list;
+
+	spin_lock(&dlm->track_lock);
+	if (oldres)
+		track_list = &oldres->tracking;
+	else {
+		track_list = &dlm->tracking_list;
+		if (list_empty(track_list)) {
+			dl = NULL;
+			spin_unlock(&dlm->track_lock);
+			goto bail;
+		}
+	}
+
+	list_for_each_entry(iter, track_list, tracking) {
+		if (&iter->tracking != &dlm->tracking_list) {
+			dlm_lockres_get(iter);
+			res = iter;
+		}
+		break;
+	}
+	spin_unlock(&dlm->track_lock);
+
+	if (oldres)
+		dlm_lockres_put(oldres);
+
+	dl->dl_res = res;
+
+	if (res) {
+		spin_lock(&res->spinlock);
+		dump_lockres(res, dl->dl_buf, dl->dl_len - 1);
+		spin_unlock(&res->spinlock);
+	} else
+		dl = NULL;
+
+bail:
+	/* passed to seq_show */
+	return dl;
+}
+
+static void lockres_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static void *lockres_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return NULL;
+}
+
+static int lockres_seq_show(struct seq_file *s, void *v)
+{
+	struct debug_lockres *dl = (struct debug_lockres *)v;
+
+	seq_printf(s, "%s", dl->dl_buf);
+
+	return 0;
+}
+
+static const struct seq_operations debug_lockres_ops = {
+	.start =	lockres_seq_start,
+	.stop =		lockres_seq_stop,
+	.next =		lockres_seq_next,
+	.show =		lockres_seq_show,
+};
+
+static int debug_lockres_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	struct debug_lockres *dl;
+	void *buf;
+
+	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		goto bail;
+
+	dl = __seq_open_private(file, &debug_lockres_ops, sizeof(*dl));
+	if (!dl)
+		goto bailfree;
+
+	dl->dl_len = PAGE_SIZE;
+	dl->dl_buf = buf;
+
+	dlm_grab(dlm);
+	dl->dl_ctxt = dlm;
+
+	return 0;
+
+bailfree:
+	kfree(buf);
+bail:
+	mlog_errno(-ENOMEM);
+	return -ENOMEM;
+}
+
+static int debug_lockres_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+	struct debug_lockres *dl = (struct debug_lockres *)seq->private;
+
+	if (dl->dl_res)
+		dlm_lockres_put(dl->dl_res);
+	dlm_put(dl->dl_ctxt);
+	kfree(dl->dl_buf);
+	return seq_release_private(inode, file);
+}
+
+static const struct file_operations debug_lockres_fops = {
+	.open =		debug_lockres_open,
+	.release =	debug_lockres_release,
+	.read =		seq_read,
+	.llseek =	seq_lseek,
+};
+/* end - debug lockres funcs */
+
+/* begin - debug state funcs */
+static int debug_state_print(struct dlm_ctxt *dlm, char *buf, int len)
+{
+	int out = 0;
+	struct dlm_reco_node_data *node;
+	char *state;
+	int cur_mles = 0, tot_mles = 0;
+	int i;
+
+	spin_lock(&dlm->spinlock);
+
+	switch (dlm->dlm_state) {
+	case DLM_CTXT_NEW:
+		state = "NEW"; break;
+	case DLM_CTXT_JOINED:
+		state = "JOINED"; break;
+	case DLM_CTXT_IN_SHUTDOWN:
+		state = "SHUTDOWN"; break;
+	case DLM_CTXT_LEAVING:
+		state = "LEAVING"; break;
+	default:
+		state = "UNKNOWN"; break;
+	}
+
+	/* Domain: xxxxxxxxxx  Key: 0xdfbac769 */
+	out += scnprintf(buf + out, len - out,
+			"Domain: %s  Key: 0x%08x  Protocol: %d.%d\n",
+			dlm->name, dlm->key, dlm->dlm_locking_proto.pv_major,
+			dlm->dlm_locking_proto.pv_minor);
+
+	/* Thread Pid: xxx  Node: xxx  State: xxxxx */
+	out += scnprintf(buf + out, len - out,
+			"Thread Pid: %d  Node: %d  State: %s\n",
+			task_pid_nr(dlm->dlm_thread_task), dlm->node_num, state);
+
+	/* Number of Joins: xxx  Joining Node: xxx */
+	out += scnprintf(buf + out, len - out,
+			"Number of Joins: %d  Joining Node: %d\n",
+			dlm->num_joins, dlm->joining_node);
+
+	/* Domain Map: xx xx xx */
+	out += scnprintf(buf + out, len - out, "Domain Map: ");
+	out += stringify_nodemap(dlm->domain_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* Exit Domain Map: xx xx xx */
+	out += scnprintf(buf + out, len - out, "Exit Domain Map: ");
+	out += stringify_nodemap(dlm->exit_domain_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* Live Map: xx xx xx */
+	out += scnprintf(buf + out, len - out, "Live Map: ");
+	out += stringify_nodemap(dlm->live_nodes_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* Lock Resources: xxx (xxx) */
+	out += scnprintf(buf + out, len - out,
+			"Lock Resources: %d (%d)\n",
+			atomic_read(&dlm->res_cur_count),
+			atomic_read(&dlm->res_tot_count));
+
+	for (i = 0; i < DLM_MLE_NUM_TYPES; ++i)
+		tot_mles += atomic_read(&dlm->mle_tot_count[i]);
+
+	for (i = 0; i < DLM_MLE_NUM_TYPES; ++i)
+		cur_mles += atomic_read(&dlm->mle_cur_count[i]);
+
+	/* MLEs: xxx (xxx) */
+	out += scnprintf(buf + out, len - out,
+			"MLEs: %d (%d)\n", cur_mles, tot_mles);
+
+	/*  Blocking: xxx (xxx) */
+	out += scnprintf(buf + out, len - out,
+			"  Blocking: %d (%d)\n",
+			atomic_read(&dlm->mle_cur_count[DLM_MLE_BLOCK]),
+			atomic_read(&dlm->mle_tot_count[DLM_MLE_BLOCK]));
+
+	/*  Mastery: xxx (xxx) */
+	out += scnprintf(buf + out, len - out,
+			"  Mastery: %d (%d)\n",
+			atomic_read(&dlm->mle_cur_count[DLM_MLE_MASTER]),
+			atomic_read(&dlm->mle_tot_count[DLM_MLE_MASTER]));
+
+	/*  Migration: xxx (xxx) */
+	out += scnprintf(buf + out, len - out,
+			"  Migration: %d (%d)\n",
+			atomic_read(&dlm->mle_cur_count[DLM_MLE_MIGRATION]),
+			atomic_read(&dlm->mle_tot_count[DLM_MLE_MIGRATION]));
+
+	/* Lists: Dirty=Empty  Purge=InUse  PendingASTs=Empty  ... */
+	out += scnprintf(buf + out, len - out,
+			"Lists: Dirty=%s  Purge=%s  PendingASTs=%s  "
+			"PendingBASTs=%s\n",
+			(list_empty(&dlm->dirty_list) ? "Empty" : "InUse"),
+			(list_empty(&dlm->purge_list) ? "Empty" : "InUse"),
+			(list_empty(&dlm->pending_asts) ? "Empty" : "InUse"),
+			(list_empty(&dlm->pending_basts) ? "Empty" : "InUse"));
+
+	/* Purge Count: xxx  Refs: xxx */
+	out += scnprintf(buf + out, len - out,
+			"Purge Count: %d  Refs: %d\n", dlm->purge_count,
+			kref_read(&dlm->dlm_refs));
+
+	/* Dead Node: xxx */
+	out += scnprintf(buf + out, len - out,
+			"Dead Node: %d\n", dlm->reco.dead_node);
+
+	/* What about DLM_RECO_STATE_FINALIZE? */
+	if (dlm->reco.state == DLM_RECO_STATE_ACTIVE)
+		state = "ACTIVE";
+	else
+		state = "INACTIVE";
+
+	/* Recovery Pid: xxxx  Master: xxx  State: xxxx */
+	out += scnprintf(buf + out, len - out,
+			"Recovery Pid: %d  Master: %d  State: %s\n",
+			task_pid_nr(dlm->dlm_reco_thread_task),
+			dlm->reco.new_master, state);
+
+	/* Recovery Map: xx xx */
+	out += scnprintf(buf + out, len - out, "Recovery Map: ");
+	out += stringify_nodemap(dlm->recovery_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += scnprintf(buf + out, len - out, "\n");
+
+	/* Recovery Node State: */
+	out += scnprintf(buf + out, len - out, "Recovery Node State:\n");
+	list_for_each_entry(node, &dlm->reco.node_data, list) {
+		switch (node->state) {
+		case DLM_RECO_NODE_DATA_INIT:
+			state = "INIT";
+			break;
+		case DLM_RECO_NODE_DATA_REQUESTING:
+			state = "REQUESTING";
+			break;
+		case DLM_RECO_NODE_DATA_DEAD:
+			state = "DEAD";
+			break;
+		case DLM_RECO_NODE_DATA_RECEIVING:
+			state = "RECEIVING";
+			break;
+		case DLM_RECO_NODE_DATA_REQUESTED:
+			state = "REQUESTED";
+			break;
+		case DLM_RECO_NODE_DATA_DONE:
+			state = "DONE";
+			break;
+		case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+			state = "FINALIZE-SENT";
+			break;
+		default:
+			state = "BAD";
+			break;
+		}
+		out += scnprintf(buf + out, len - out, "\t%u - %s\n",
+				node->node_num, state);
+	}
+
+	spin_unlock(&dlm->spinlock);
+
+	return out;
+}
+
+static int debug_state_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	char *buf = NULL;
+
+	buf = (char *) get_zeroed_page(GFP_NOFS);
+	if (!buf)
+		goto bail;
+
+	i_size_write(inode, debug_state_print(dlm, buf, PAGE_SIZE - 1));
+
+	file->private_data = buf;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static const struct file_operations debug_state_fops = {
+	.open =		debug_state_open,
+	.release =	debug_release,
+	.read =		debug_read,
+	.llseek =	generic_file_llseek,
+};
+/* end  - debug state funcs */
+
+/* files in subroot */
+void dlm_debug_init(struct dlm_ctxt *dlm)
+{
+	/* for dumping dlm_ctxt */
+	debugfs_create_file(DLM_DEBUGFS_DLM_STATE, S_IFREG|S_IRUSR,
+			    dlm->dlm_debugfs_subroot, dlm, &debug_state_fops);
+
+	/* for dumping lockres */
+	debugfs_create_file(DLM_DEBUGFS_LOCKING_STATE, S_IFREG|S_IRUSR,
+			    dlm->dlm_debugfs_subroot, dlm, &debug_lockres_fops);
+
+	/* for dumping mles */
+	debugfs_create_file(DLM_DEBUGFS_MLE_STATE, S_IFREG|S_IRUSR,
+			    dlm->dlm_debugfs_subroot, dlm, &debug_mle_fops);
+
+	/* for dumping lockres on the purge list */
+	debugfs_create_file(DLM_DEBUGFS_PURGE_LIST, S_IFREG|S_IRUSR,
+			    dlm->dlm_debugfs_subroot, dlm,
+			    &debug_purgelist_fops);
+}
+
+/* subroot - domain dir */
+void dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+	dlm->dlm_debugfs_subroot = debugfs_create_dir(dlm->name,
+						      dlm_debugfs_root);
+}
+
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+	debugfs_remove_recursive(dlm->dlm_debugfs_subroot);
+}
+
+/* debugfs root */
+void dlm_create_debugfs_root(void)
+{
+	dlm_debugfs_root = debugfs_create_dir(DLM_DEBUGFS_DIR, NULL);
+}
+
+void dlm_destroy_debugfs_root(void)
+{
+	debugfs_remove(dlm_debugfs_root);
+}
+#endif	/* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/dlm/dlmdebug.h b/fs/ocfs2/dlm/dlmdebug.h
new file mode 100644
index 000000000..e08f7357e
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdebug.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmdebug.h
+ *
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ */
+
+#ifndef DLMDEBUG_H
+#define DLMDEBUG_H
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle);
+
+#ifdef CONFIG_DEBUG_FS
+
+struct debug_lockres {
+	int dl_len;
+	char *dl_buf;
+	struct dlm_ctxt *dl_ctxt;
+	struct dlm_lock_resource *dl_res;
+};
+
+void dlm_debug_init(struct dlm_ctxt *dlm);
+
+void dlm_create_debugfs_subroot(struct dlm_ctxt *dlm);
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm);
+
+void dlm_create_debugfs_root(void);
+void dlm_destroy_debugfs_root(void);
+
+#else
+
+static inline void dlm_debug_init(struct dlm_ctxt *dlm)
+{
+}
+static inline void dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+}
+static inline void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+}
+static inline void dlm_create_debugfs_root(void)
+{
+}
+static inline void dlm_destroy_debugfs_root(void)
+{
+}
+
+#endif	/* CONFIG_DEBUG_FS */
+#endif	/* DLMDEBUG_H */
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
new file mode 100644
index 000000000..c4eccd499
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -0,0 +1,2365 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmdomain.c
+ *
+ * defines domain join / leave apis
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/debugfs.h>
+#include <linux/sched/signal.h>
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+#include "dlmdebug.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_DOMAIN)
+#include "../cluster/masklog.h"
+
+/*
+ * ocfs2 node maps are array of long int, which limits to send them freely
+ * across the wire due to endianness issues. To workaround this, we convert
+ * long ints to byte arrays. Following 3 routines are helper functions to
+ * set/test/copy bits within those array of bytes
+ */
+static inline void byte_set_bit(u8 nr, u8 map[])
+{
+	map[nr >> 3] |= (1UL << (nr & 7));
+}
+
+static inline int byte_test_bit(u8 nr, u8 map[])
+{
+	return ((1UL << (nr & 7)) & (map[nr >> 3])) != 0;
+}
+
+static inline void byte_copymap(u8 dmap[], unsigned long smap[],
+			unsigned int sz)
+{
+	unsigned int nn;
+
+	if (!sz)
+		return;
+
+	memset(dmap, 0, ((sz + 7) >> 3));
+	for (nn = 0 ; nn < sz; nn++)
+		if (test_bit(nn, smap))
+			byte_set_bit(nn, dmap);
+}
+
+static void dlm_free_pagevec(void **vec, int pages)
+{
+	while (pages--)
+		free_page((unsigned long)vec[pages]);
+	kfree(vec);
+}
+
+static void **dlm_alloc_pagevec(int pages)
+{
+	void **vec = kmalloc_array(pages, sizeof(void *), GFP_KERNEL);
+	int i;
+
+	if (!vec)
+		return NULL;
+
+	for (i = 0; i < pages; i++)
+		if (!(vec[i] = (void *)__get_free_page(GFP_KERNEL)))
+			goto out_free;
+
+	mlog(0, "Allocated DLM hash pagevec; %d pages (%lu expected), %lu buckets per page\n",
+	     pages, (unsigned long)DLM_HASH_PAGES,
+	     (unsigned long)DLM_BUCKETS_PER_PAGE);
+	return vec;
+out_free:
+	dlm_free_pagevec(vec, i);
+	return NULL;
+}
+
+/*
+ *
+ * spinlock lock ordering: if multiple locks are needed, obey this ordering:
+ *    dlm_domain_lock
+ *    struct dlm_ctxt->spinlock
+ *    struct dlm_lock_resource->spinlock
+ *    struct dlm_ctxt->master_lock
+ *    struct dlm_ctxt->ast_lock
+ *    dlm_master_list_entry->spinlock
+ *    dlm_lock->spinlock
+ *
+ */
+
+DEFINE_SPINLOCK(dlm_domain_lock);
+LIST_HEAD(dlm_domains);
+static DECLARE_WAIT_QUEUE_HEAD(dlm_domain_events);
+
+/*
+ * The supported protocol version for DLM communication.  Running domains
+ * will have a negotiated version with the same major number and a minor
+ * number equal or smaller.  The dlm_ctxt->dlm_locking_proto field should
+ * be used to determine what a running domain is actually using.
+ *
+ * New in version 1.1:
+ *	- Message DLM_QUERY_REGION added to support global heartbeat
+ *	- Message DLM_QUERY_NODEINFO added to allow online node removes
+ * New in version 1.2:
+ * 	- Message DLM_BEGIN_EXIT_DOMAIN_MSG added to mark start of exit domain
+ * New in version 1.3:
+ *	- Message DLM_DEREF_LOCKRES_DONE added to inform non-master that the
+ *	  refmap is cleared
+ */
+static const struct dlm_protocol_version dlm_protocol = {
+	.pv_major = 1,
+	.pv_minor = 3,
+};
+
+#define DLM_DOMAIN_BACKOFF_MS 200
+
+static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
+				  void **ret_data);
+static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
+				     void **ret_data);
+static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
+				   void **ret_data);
+static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
+				    void *data, void **ret_data);
+static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
+				   void **ret_data);
+static int dlm_protocol_compare(struct dlm_protocol_version *existing,
+				struct dlm_protocol_version *request);
+
+static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
+
+void __dlm_unhash_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+	if (hlist_unhashed(&res->hash_node))
+		return;
+
+	mlog(0, "%s: Unhash res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+	hlist_del_init(&res->hash_node);
+	dlm_lockres_put(res);
+}
+
+void __dlm_insert_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+	struct hlist_head *bucket;
+
+	assert_spin_locked(&dlm->spinlock);
+
+	bucket = dlm_lockres_hash(dlm, res->lockname.hash);
+
+	/* get a reference for our hashtable */
+	dlm_lockres_get(res);
+
+	hlist_add_head(&res->hash_node, bucket);
+
+	mlog(0, "%s: Hash res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+}
+
+struct dlm_lock_resource * __dlm_lookup_lockres_full(struct dlm_ctxt *dlm,
+						     const char *name,
+						     unsigned int len,
+						     unsigned int hash)
+{
+	struct hlist_head *bucket;
+	struct dlm_lock_resource *res;
+
+	mlog(0, "%.*s\n", len, name);
+
+	assert_spin_locked(&dlm->spinlock);
+
+	bucket = dlm_lockres_hash(dlm, hash);
+
+	hlist_for_each_entry(res, bucket, hash_node) {
+		if (res->lockname.name[0] != name[0])
+			continue;
+		if (unlikely(res->lockname.len != len))
+			continue;
+		if (memcmp(res->lockname.name + 1, name + 1, len - 1))
+			continue;
+		dlm_lockres_get(res);
+		return res;
+	}
+	return NULL;
+}
+
+/* intended to be called by functions which do not care about lock
+ * resources which are being purged (most net _handler functions).
+ * this will return NULL for any lock resource which is found but
+ * currently in the process of dropping its mastery reference.
+ * use __dlm_lookup_lockres_full when you need the lock resource
+ * regardless (e.g. dlm_get_lock_resource) */
+struct dlm_lock_resource * __dlm_lookup_lockres(struct dlm_ctxt *dlm,
+						const char *name,
+						unsigned int len,
+						unsigned int hash)
+{
+	struct dlm_lock_resource *res = NULL;
+
+	mlog(0, "%.*s\n", len, name);
+
+	assert_spin_locked(&dlm->spinlock);
+
+	res = __dlm_lookup_lockres_full(dlm, name, len, hash);
+	if (res) {
+		spin_lock(&res->spinlock);
+		if (res->state & DLM_LOCK_RES_DROPPING_REF) {
+			spin_unlock(&res->spinlock);
+			dlm_lockres_put(res);
+			return NULL;
+		}
+		spin_unlock(&res->spinlock);
+	}
+
+	return res;
+}
+
+struct dlm_lock_resource * dlm_lookup_lockres(struct dlm_ctxt *dlm,
+				    const char *name,
+				    unsigned int len)
+{
+	struct dlm_lock_resource *res;
+	unsigned int hash = dlm_lockid_hash(name, len);
+
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres(dlm, name, len, hash);
+	spin_unlock(&dlm->spinlock);
+	return res;
+}
+
+static struct dlm_ctxt * __dlm_lookup_domain_full(const char *domain, int len)
+{
+	struct dlm_ctxt *tmp;
+
+	assert_spin_locked(&dlm_domain_lock);
+
+	/* tmp->name here is always NULL terminated,
+	 * but domain may not be! */
+	list_for_each_entry(tmp, &dlm_domains, list) {
+		if (strlen(tmp->name) == len &&
+		    memcmp(tmp->name, domain, len)==0)
+			return tmp;
+	}
+
+	return NULL;
+}
+
+/* For null terminated domain strings ONLY */
+static struct dlm_ctxt * __dlm_lookup_domain(const char *domain)
+{
+	assert_spin_locked(&dlm_domain_lock);
+
+	return __dlm_lookup_domain_full(domain, strlen(domain));
+}
+
+
+/* returns true on one of two conditions:
+ * 1) the domain does not exist
+ * 2) the domain exists and it's state is "joined" */
+static int dlm_wait_on_domain_helper(const char *domain)
+{
+	int ret = 0;
+	struct dlm_ctxt *tmp = NULL;
+
+	spin_lock(&dlm_domain_lock);
+
+	tmp = __dlm_lookup_domain(domain);
+	if (!tmp)
+		ret = 1;
+	else if (tmp->dlm_state == DLM_CTXT_JOINED)
+		ret = 1;
+
+	spin_unlock(&dlm_domain_lock);
+	return ret;
+}
+
+static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
+{
+	dlm_destroy_debugfs_subroot(dlm);
+
+	if (dlm->lockres_hash)
+		dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
+
+	if (dlm->master_hash)
+		dlm_free_pagevec((void **)dlm->master_hash, DLM_HASH_PAGES);
+
+	kfree(dlm->name);
+	kfree(dlm);
+}
+
+/* A little strange - this function will be called while holding
+ * dlm_domain_lock and is expected to be holding it on the way out. We
+ * will however drop and reacquire it multiple times */
+static void dlm_ctxt_release(struct kref *kref)
+{
+	struct dlm_ctxt *dlm;
+
+	dlm = container_of(kref, struct dlm_ctxt, dlm_refs);
+
+	BUG_ON(dlm->num_joins);
+	BUG_ON(dlm->dlm_state == DLM_CTXT_JOINED);
+
+	/* we may still be in the list if we hit an error during join. */
+	list_del_init(&dlm->list);
+
+	spin_unlock(&dlm_domain_lock);
+
+	mlog(0, "freeing memory from domain %s\n", dlm->name);
+
+	wake_up(&dlm_domain_events);
+
+	dlm_free_ctxt_mem(dlm);
+
+	spin_lock(&dlm_domain_lock);
+}
+
+void dlm_put(struct dlm_ctxt *dlm)
+{
+	spin_lock(&dlm_domain_lock);
+	kref_put(&dlm->dlm_refs, dlm_ctxt_release);
+	spin_unlock(&dlm_domain_lock);
+}
+
+static void __dlm_get(struct dlm_ctxt *dlm)
+{
+	kref_get(&dlm->dlm_refs);
+}
+
+/* given a questionable reference to a dlm object, gets a reference if
+ * it can find it in the list, otherwise returns NULL in which case
+ * you shouldn't trust your pointer. */
+struct dlm_ctxt *dlm_grab(struct dlm_ctxt *dlm)
+{
+	struct dlm_ctxt *target;
+	struct dlm_ctxt *ret = NULL;
+
+	spin_lock(&dlm_domain_lock);
+
+	list_for_each_entry(target, &dlm_domains, list) {
+		if (target == dlm) {
+			__dlm_get(target);
+			ret = target;
+			break;
+		}
+	}
+
+	spin_unlock(&dlm_domain_lock);
+
+	return ret;
+}
+
+int dlm_domain_fully_joined(struct dlm_ctxt *dlm)
+{
+	int ret;
+
+	spin_lock(&dlm_domain_lock);
+	ret = (dlm->dlm_state == DLM_CTXT_JOINED) ||
+		(dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN);
+	spin_unlock(&dlm_domain_lock);
+
+	return ret;
+}
+
+static void dlm_destroy_dlm_worker(struct dlm_ctxt *dlm)
+{
+	if (dlm->dlm_worker) {
+		destroy_workqueue(dlm->dlm_worker);
+		dlm->dlm_worker = NULL;
+	}
+}
+
+static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
+{
+	dlm_unregister_domain_handlers(dlm);
+	dlm_complete_thread(dlm);
+	dlm_complete_recovery_thread(dlm);
+	dlm_destroy_dlm_worker(dlm);
+
+	/* We've left the domain. Now we can take ourselves out of the
+	 * list and allow the kref stuff to help us free the
+	 * memory. */
+	spin_lock(&dlm_domain_lock);
+	list_del_init(&dlm->list);
+	spin_unlock(&dlm_domain_lock);
+
+	/* Wake up anyone waiting for us to remove this domain */
+	wake_up(&dlm_domain_events);
+}
+
+static int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
+{
+	int i, num, n, ret = 0;
+	struct dlm_lock_resource *res;
+	struct hlist_node *iter;
+	struct hlist_head *bucket;
+	int dropped;
+
+	mlog(0, "Migrating locks from domain %s\n", dlm->name);
+
+	num = 0;
+	spin_lock(&dlm->spinlock);
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+redo_bucket:
+		n = 0;
+		bucket = dlm_lockres_hash(dlm, i);
+		iter = bucket->first;
+		while (iter) {
+			n++;
+			res = hlist_entry(iter, struct dlm_lock_resource,
+					  hash_node);
+			dlm_lockres_get(res);
+			/* migrate, if necessary.  this will drop the dlm
+			 * spinlock and retake it if it does migration. */
+			dropped = dlm_empty_lockres(dlm, res);
+
+			spin_lock(&res->spinlock);
+			if (dropped)
+				__dlm_lockres_calc_usage(dlm, res);
+			else
+				iter = res->hash_node.next;
+			spin_unlock(&res->spinlock);
+
+			dlm_lockres_put(res);
+
+			if (dropped) {
+				cond_resched_lock(&dlm->spinlock);
+				goto redo_bucket;
+			}
+		}
+		cond_resched_lock(&dlm->spinlock);
+		num += n;
+	}
+
+	if (!num) {
+		if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "%s: perhaps there are more lock resources "
+			     "need to be migrated after dlm recovery\n", dlm->name);
+			ret = -EAGAIN;
+		} else {
+			mlog(0, "%s: we won't do dlm recovery after migrating "
+			     "all lock resources\n", dlm->name);
+			dlm->migrate_done = 1;
+		}
+	}
+
+	spin_unlock(&dlm->spinlock);
+	wake_up(&dlm->dlm_thread_wq);
+
+	/* let the dlm thread take care of purging, keep scanning until
+	 * nothing remains in the hash */
+	if (num) {
+		mlog(0, "%s: %d lock resources in hash last pass\n",
+		     dlm->name, num);
+		ret = -EAGAIN;
+	}
+	mlog(0, "DONE Migrating locks from domain %s\n", dlm->name);
+	return ret;
+}
+
+static int dlm_no_joining_node(struct dlm_ctxt *dlm)
+{
+	int ret;
+
+	spin_lock(&dlm->spinlock);
+	ret = dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN;
+	spin_unlock(&dlm->spinlock);
+
+	return ret;
+}
+
+static int dlm_begin_exit_domain_handler(struct o2net_msg *msg, u32 len,
+					 void *data, void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	unsigned int node;
+	struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	node = exit_msg->node_idx;
+	mlog(0, "%s: Node %u sent a begin exit domain message\n", dlm->name, node);
+
+	spin_lock(&dlm->spinlock);
+	set_bit(node, dlm->exit_domain_map);
+	spin_unlock(&dlm->spinlock);
+
+	dlm_put(dlm);
+
+	return 0;
+}
+
+static void dlm_mark_domain_leaving(struct dlm_ctxt *dlm)
+{
+	/* Yikes, a double spinlock! I need domain_lock for the dlm
+	 * state and the dlm spinlock for join state... Sorry! */
+again:
+	spin_lock(&dlm_domain_lock);
+	spin_lock(&dlm->spinlock);
+
+	if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
+		mlog(0, "Node %d is joining, we wait on it.\n",
+			  dlm->joining_node);
+		spin_unlock(&dlm->spinlock);
+		spin_unlock(&dlm_domain_lock);
+
+		wait_event(dlm->dlm_join_events, dlm_no_joining_node(dlm));
+		goto again;
+	}
+
+	dlm->dlm_state = DLM_CTXT_LEAVING;
+	spin_unlock(&dlm->spinlock);
+	spin_unlock(&dlm_domain_lock);
+}
+
+static void __dlm_print_nodes(struct dlm_ctxt *dlm)
+{
+	int node = -1, num = 0;
+
+	assert_spin_locked(&dlm->spinlock);
+
+	printk("( ");
+	while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
+				     node + 1)) < O2NM_MAX_NODES) {
+		printk("%d ", node);
+		++num;
+	}
+	printk(") %u nodes\n", num);
+}
+
+static int dlm_exit_domain_handler(struct o2net_msg *msg, u32 len, void *data,
+				   void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	unsigned int node;
+	struct dlm_exit_domain *exit_msg = (struct dlm_exit_domain *) msg->buf;
+
+	mlog(0, "%p %u %p", msg, len, data);
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	node = exit_msg->node_idx;
+
+	spin_lock(&dlm->spinlock);
+	clear_bit(node, dlm->domain_map);
+	clear_bit(node, dlm->exit_domain_map);
+	printk(KERN_NOTICE "o2dlm: Node %u leaves domain %s ", node, dlm->name);
+	__dlm_print_nodes(dlm);
+
+	/* notify anything attached to the heartbeat events */
+	dlm_hb_event_notify_attached(dlm, node, 0);
+
+	spin_unlock(&dlm->spinlock);
+
+	dlm_put(dlm);
+
+	return 0;
+}
+
+static int dlm_send_one_domain_exit(struct dlm_ctxt *dlm, u32 msg_type,
+				    unsigned int node)
+{
+	int status;
+	struct dlm_exit_domain leave_msg;
+
+	mlog(0, "%s: Sending domain exit message %u to node %u\n", dlm->name,
+	     msg_type, node);
+
+	memset(&leave_msg, 0, sizeof(leave_msg));
+	leave_msg.node_idx = dlm->node_num;
+
+	status = o2net_send_message(msg_type, dlm->key, &leave_msg,
+				    sizeof(leave_msg), node, NULL);
+	if (status < 0)
+		mlog(ML_ERROR, "Error %d sending domain exit message %u "
+		     "to node %u on domain %s\n", status, msg_type, node,
+		     dlm->name);
+
+	return status;
+}
+
+static void dlm_begin_exit_domain(struct dlm_ctxt *dlm)
+{
+	int node = -1;
+
+	/* Support for begin exit domain was added in 1.2 */
+	if (dlm->dlm_locking_proto.pv_major == 1 &&
+	    dlm->dlm_locking_proto.pv_minor < 2)
+		return;
+
+	/*
+	 * Unlike DLM_EXIT_DOMAIN_MSG, DLM_BEGIN_EXIT_DOMAIN_MSG is purely
+	 * informational. Meaning if a node does not receive the message,
+	 * so be it.
+	 */
+	spin_lock(&dlm->spinlock);
+	while (1) {
+		node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES, node + 1);
+		if (node >= O2NM_MAX_NODES)
+			break;
+		if (node == dlm->node_num)
+			continue;
+
+		spin_unlock(&dlm->spinlock);
+		dlm_send_one_domain_exit(dlm, DLM_BEGIN_EXIT_DOMAIN_MSG, node);
+		spin_lock(&dlm->spinlock);
+	}
+	spin_unlock(&dlm->spinlock);
+}
+
+static void dlm_leave_domain(struct dlm_ctxt *dlm)
+{
+	int node, clear_node, status;
+
+	/* At this point we've migrated away all our locks and won't
+	 * accept mastership of new ones. The dlm is responsible for
+	 * almost nothing now. We make sure not to confuse any joining
+	 * nodes and then commence shutdown procedure. */
+
+	spin_lock(&dlm->spinlock);
+	/* Clear ourselves from the domain map */
+	clear_bit(dlm->node_num, dlm->domain_map);
+	while ((node = find_next_bit(dlm->domain_map, O2NM_MAX_NODES,
+				     0)) < O2NM_MAX_NODES) {
+		/* Drop the dlm spinlock. This is safe wrt the domain_map.
+		 * -nodes cannot be added now as the
+		 *   query_join_handlers knows to respond with OK_NO_MAP
+		 * -we catch the right network errors if a node is
+		 *   removed from the map while we're sending him the
+		 *   exit message. */
+		spin_unlock(&dlm->spinlock);
+
+		clear_node = 1;
+
+		status = dlm_send_one_domain_exit(dlm, DLM_EXIT_DOMAIN_MSG,
+						  node);
+		if (status < 0 &&
+		    status != -ENOPROTOOPT &&
+		    status != -ENOTCONN) {
+			mlog(ML_NOTICE, "Error %d sending domain exit message "
+			     "to node %d\n", status, node);
+
+			/* Not sure what to do here but lets sleep for
+			 * a bit in case this was a transient
+			 * error... */
+			msleep(DLM_DOMAIN_BACKOFF_MS);
+			clear_node = 0;
+		}
+
+		spin_lock(&dlm->spinlock);
+		/* If we're not clearing the node bit then we intend
+		 * to loop back around to try again. */
+		if (clear_node)
+			clear_bit(node, dlm->domain_map);
+	}
+	spin_unlock(&dlm->spinlock);
+}
+
+void dlm_unregister_domain(struct dlm_ctxt *dlm)
+{
+	int leave = 0;
+	struct dlm_lock_resource *res;
+
+	spin_lock(&dlm_domain_lock);
+	BUG_ON(dlm->dlm_state != DLM_CTXT_JOINED);
+	BUG_ON(!dlm->num_joins);
+
+	dlm->num_joins--;
+	if (!dlm->num_joins) {
+		/* We mark it "in shutdown" now so new register
+		 * requests wait until we've completely left the
+		 * domain. Don't use DLM_CTXT_LEAVING yet as we still
+		 * want new domain joins to communicate with us at
+		 * least until we've completed migration of our
+		 * resources. */
+		dlm->dlm_state = DLM_CTXT_IN_SHUTDOWN;
+		leave = 1;
+	}
+	spin_unlock(&dlm_domain_lock);
+
+	if (leave) {
+		mlog(0, "shutting down domain %s\n", dlm->name);
+		dlm_begin_exit_domain(dlm);
+
+		/* We changed dlm state, notify the thread */
+		dlm_kick_thread(dlm, NULL);
+
+		while (dlm_migrate_all_locks(dlm)) {
+			/* Give dlm_thread time to purge the lockres' */
+			msleep(500);
+			mlog(0, "%s: more migration to do\n", dlm->name);
+		}
+
+		/* This list should be empty. If not, print remaining lockres */
+		if (!list_empty(&dlm->tracking_list)) {
+			mlog(ML_ERROR, "Following lockres' are still on the "
+			     "tracking list:\n");
+			list_for_each_entry(res, &dlm->tracking_list, tracking)
+				dlm_print_one_lock_resource(res);
+		}
+
+		dlm_mark_domain_leaving(dlm);
+		dlm_leave_domain(dlm);
+		printk(KERN_NOTICE "o2dlm: Leaving domain %s\n", dlm->name);
+		dlm_force_free_mles(dlm);
+		dlm_complete_dlm_shutdown(dlm);
+	}
+	dlm_put(dlm);
+}
+EXPORT_SYMBOL_GPL(dlm_unregister_domain);
+
+static int dlm_query_join_proto_check(char *proto_type, int node,
+				      struct dlm_protocol_version *ours,
+				      struct dlm_protocol_version *request)
+{
+	int rc;
+	struct dlm_protocol_version proto = *request;
+
+	if (!dlm_protocol_compare(ours, &proto)) {
+		mlog(0,
+		     "node %u wanted to join with %s locking protocol "
+		     "%u.%u, we respond with %u.%u\n",
+		     node, proto_type,
+		     request->pv_major,
+		     request->pv_minor,
+		     proto.pv_major, proto.pv_minor);
+		request->pv_minor = proto.pv_minor;
+		rc = 0;
+	} else {
+		mlog(ML_NOTICE,
+		     "Node %u wanted to join with %s locking "
+		     "protocol %u.%u, but we have %u.%u, disallowing\n",
+		     node, proto_type,
+		     request->pv_major,
+		     request->pv_minor,
+		     ours->pv_major,
+		     ours->pv_minor);
+		rc = 1;
+	}
+
+	return rc;
+}
+
+/*
+ * struct dlm_query_join_packet is made up of four one-byte fields.  They
+ * are effectively in big-endian order already.  However, little-endian
+ * machines swap them before putting the packet on the wire (because
+ * query_join's response is a status, and that status is treated as a u32
+ * on the wire).  Thus, a big-endian and little-endian machines will treat
+ * this structure differently.
+ *
+ * The solution is to have little-endian machines swap the structure when
+ * converting from the structure to the u32 representation.  This will
+ * result in the structure having the correct format on the wire no matter
+ * the host endian format.
+ */
+static void dlm_query_join_packet_to_wire(struct dlm_query_join_packet *packet,
+					  u32 *wire)
+{
+	union dlm_query_join_response response;
+
+	response.packet = *packet;
+	*wire = be32_to_cpu(response.intval);
+}
+
+static void dlm_query_join_wire_to_packet(u32 wire,
+					  struct dlm_query_join_packet *packet)
+{
+	union dlm_query_join_response response;
+
+	response.intval = cpu_to_be32(wire);
+	*packet = response.packet;
+}
+
+static int dlm_query_join_handler(struct o2net_msg *msg, u32 len, void *data,
+				  void **ret_data)
+{
+	struct dlm_query_join_request *query;
+	struct dlm_query_join_packet packet = {
+		.code = JOIN_DISALLOW,
+	};
+	struct dlm_ctxt *dlm = NULL;
+	u32 response;
+	u8 nodenum;
+
+	query = (struct dlm_query_join_request *) msg->buf;
+
+	mlog(0, "node %u wants to join domain %s\n", query->node_idx,
+		  query->domain);
+
+	/*
+	 * If heartbeat doesn't consider the node live, tell it
+	 * to back off and try again.  This gives heartbeat a chance
+	 * to catch up.
+	 */
+	if (!o2hb_check_node_heartbeating_no_sem(query->node_idx)) {
+		mlog(0, "node %u is not in our live map yet\n",
+		     query->node_idx);
+
+		packet.code = JOIN_DISALLOW;
+		goto respond;
+	}
+
+	packet.code = JOIN_OK_NO_MAP;
+
+	spin_lock(&dlm_domain_lock);
+	dlm = __dlm_lookup_domain_full(query->domain, query->name_len);
+	if (!dlm)
+		goto unlock_respond;
+
+	/*
+	 * There is a small window where the joining node may not see the
+	 * node(s) that just left but still part of the cluster. DISALLOW
+	 * join request if joining node has different node map.
+	 */
+	nodenum=0;
+	while (nodenum < O2NM_MAX_NODES) {
+		if (test_bit(nodenum, dlm->domain_map)) {
+			if (!byte_test_bit(nodenum, query->node_map)) {
+				mlog(0, "disallow join as node %u does not "
+				     "have node %u in its nodemap\n",
+				     query->node_idx, nodenum);
+				packet.code = JOIN_DISALLOW;
+				goto unlock_respond;
+			}
+		}
+		nodenum++;
+	}
+
+	/* Once the dlm ctxt is marked as leaving then we don't want
+	 * to be put in someone's domain map.
+	 * Also, explicitly disallow joining at certain troublesome
+	 * times (ie. during recovery). */
+	if (dlm->dlm_state != DLM_CTXT_LEAVING) {
+		int bit = query->node_idx;
+		spin_lock(&dlm->spinlock);
+
+		if (dlm->dlm_state == DLM_CTXT_NEW &&
+		    dlm->joining_node == DLM_LOCK_RES_OWNER_UNKNOWN) {
+			/*If this is a brand new context and we
+			 * haven't started our join process yet, then
+			 * the other node won the race. */
+			packet.code = JOIN_OK_NO_MAP;
+		} else if (dlm->joining_node != DLM_LOCK_RES_OWNER_UNKNOWN) {
+			/* Disallow parallel joins. */
+			packet.code = JOIN_DISALLOW;
+		} else if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "node %u trying to join, but recovery "
+			     "is ongoing.\n", bit);
+			packet.code = JOIN_DISALLOW;
+		} else if (test_bit(bit, dlm->recovery_map)) {
+			mlog(0, "node %u trying to join, but it "
+			     "still needs recovery.\n", bit);
+			packet.code = JOIN_DISALLOW;
+		} else if (test_bit(bit, dlm->domain_map)) {
+			mlog(0, "node %u trying to join, but it "
+			     "is still in the domain! needs recovery?\n",
+			     bit);
+			packet.code = JOIN_DISALLOW;
+		} else {
+			/* Alright we're fully a part of this domain
+			 * so we keep some state as to who's joining
+			 * and indicate to him that needs to be fixed
+			 * up. */
+
+			/* Make sure we speak compatible locking protocols.  */
+			if (dlm_query_join_proto_check("DLM", bit,
+						       &dlm->dlm_locking_proto,
+						       &query->dlm_proto)) {
+				packet.code = JOIN_PROTOCOL_MISMATCH;
+			} else if (dlm_query_join_proto_check("fs", bit,
+							      &dlm->fs_locking_proto,
+							      &query->fs_proto)) {
+				packet.code = JOIN_PROTOCOL_MISMATCH;
+			} else {
+				packet.dlm_minor = query->dlm_proto.pv_minor;
+				packet.fs_minor = query->fs_proto.pv_minor;
+				packet.code = JOIN_OK;
+				__dlm_set_joining_node(dlm, query->node_idx);
+			}
+		}
+
+		spin_unlock(&dlm->spinlock);
+	}
+unlock_respond:
+	spin_unlock(&dlm_domain_lock);
+
+respond:
+	mlog(0, "We respond with %u\n", packet.code);
+
+	dlm_query_join_packet_to_wire(&packet, &response);
+	return response;
+}
+
+static int dlm_assert_joined_handler(struct o2net_msg *msg, u32 len, void *data,
+				     void **ret_data)
+{
+	struct dlm_assert_joined *assert;
+	struct dlm_ctxt *dlm = NULL;
+
+	assert = (struct dlm_assert_joined *) msg->buf;
+
+	mlog(0, "node %u asserts join on domain %s\n", assert->node_idx,
+		  assert->domain);
+
+	spin_lock(&dlm_domain_lock);
+	dlm = __dlm_lookup_domain_full(assert->domain, assert->name_len);
+	/* XXX should we consider no dlm ctxt an error? */
+	if (dlm) {
+		spin_lock(&dlm->spinlock);
+
+		/* Alright, this node has officially joined our
+		 * domain. Set him in the map and clean up our
+		 * leftover join state. */
+		BUG_ON(dlm->joining_node != assert->node_idx);
+
+		if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "dlm recovery is ongoing, disallow join\n");
+			spin_unlock(&dlm->spinlock);
+			spin_unlock(&dlm_domain_lock);
+			return -EAGAIN;
+		}
+
+		set_bit(assert->node_idx, dlm->domain_map);
+		clear_bit(assert->node_idx, dlm->exit_domain_map);
+		__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+
+		printk(KERN_NOTICE "o2dlm: Node %u joins domain %s ",
+		       assert->node_idx, dlm->name);
+		__dlm_print_nodes(dlm);
+
+		/* notify anything attached to the heartbeat events */
+		dlm_hb_event_notify_attached(dlm, assert->node_idx, 1);
+
+		spin_unlock(&dlm->spinlock);
+	}
+	spin_unlock(&dlm_domain_lock);
+
+	return 0;
+}
+
+static int dlm_match_regions(struct dlm_ctxt *dlm,
+			     struct dlm_query_region *qr,
+			     char *local, int locallen)
+{
+	char *remote = qr->qr_regions;
+	char *l, *r;
+	int localnr, i, j, foundit;
+	int status = 0;
+
+	if (!o2hb_global_heartbeat_active()) {
+		if (qr->qr_numregions) {
+			mlog(ML_ERROR, "Domain %s: Joining node %d has global "
+			     "heartbeat enabled but local node %d does not\n",
+			     qr->qr_domain, qr->qr_node, dlm->node_num);
+			status = -EINVAL;
+		}
+		goto bail;
+	}
+
+	if (o2hb_global_heartbeat_active() && !qr->qr_numregions) {
+		mlog(ML_ERROR, "Domain %s: Local node %d has global "
+		     "heartbeat enabled but joining node %d does not\n",
+		     qr->qr_domain, dlm->node_num, qr->qr_node);
+		status = -EINVAL;
+		goto bail;
+	}
+
+	r = remote;
+	for (i = 0; i < qr->qr_numregions; ++i) {
+		mlog(0, "Region %.*s\n", O2HB_MAX_REGION_NAME_LEN, r);
+		r += O2HB_MAX_REGION_NAME_LEN;
+	}
+
+	localnr = min(O2NM_MAX_REGIONS, locallen/O2HB_MAX_REGION_NAME_LEN);
+	localnr = o2hb_get_all_regions(local, (u8)localnr);
+
+	/* compare local regions with remote */
+	l = local;
+	for (i = 0; i < localnr; ++i) {
+		foundit = 0;
+		r = remote;
+		for (j = 0; j <= qr->qr_numregions; ++j) {
+			if (!memcmp(l, r, O2HB_MAX_REGION_NAME_LEN)) {
+				foundit = 1;
+				break;
+			}
+			r += O2HB_MAX_REGION_NAME_LEN;
+		}
+		if (!foundit) {
+			status = -EINVAL;
+			mlog(ML_ERROR, "Domain %s: Region '%.*s' registered "
+			     "in local node %d but not in joining node %d\n",
+			     qr->qr_domain, O2HB_MAX_REGION_NAME_LEN, l,
+			     dlm->node_num, qr->qr_node);
+			goto bail;
+		}
+		l += O2HB_MAX_REGION_NAME_LEN;
+	}
+
+	/* compare remote with local regions */
+	r = remote;
+	for (i = 0; i < qr->qr_numregions; ++i) {
+		foundit = 0;
+		l = local;
+		for (j = 0; j < localnr; ++j) {
+			if (!memcmp(r, l, O2HB_MAX_REGION_NAME_LEN)) {
+				foundit = 1;
+				break;
+			}
+			l += O2HB_MAX_REGION_NAME_LEN;
+		}
+		if (!foundit) {
+			status = -EINVAL;
+			mlog(ML_ERROR, "Domain %s: Region '%.*s' registered "
+			     "in joining node %d but not in local node %d\n",
+			     qr->qr_domain, O2HB_MAX_REGION_NAME_LEN, r,
+			     qr->qr_node, dlm->node_num);
+			goto bail;
+		}
+		r += O2HB_MAX_REGION_NAME_LEN;
+	}
+
+bail:
+	return status;
+}
+
+static int dlm_send_regions(struct dlm_ctxt *dlm, unsigned long *node_map)
+{
+	struct dlm_query_region *qr = NULL;
+	int status, ret = 0, i;
+	char *p;
+
+	if (find_first_bit(node_map, O2NM_MAX_NODES) >= O2NM_MAX_NODES)
+		goto bail;
+
+	qr = kzalloc(sizeof(struct dlm_query_region), GFP_KERNEL);
+	if (!qr) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	qr->qr_node = dlm->node_num;
+	qr->qr_namelen = strlen(dlm->name);
+	memcpy(qr->qr_domain, dlm->name, qr->qr_namelen);
+	/* if local hb, the numregions will be zero */
+	if (o2hb_global_heartbeat_active())
+		qr->qr_numregions = o2hb_get_all_regions(qr->qr_regions,
+							 O2NM_MAX_REGIONS);
+
+	p = qr->qr_regions;
+	for (i = 0; i < qr->qr_numregions; ++i, p += O2HB_MAX_REGION_NAME_LEN)
+		mlog(0, "Region %.*s\n", O2HB_MAX_REGION_NAME_LEN, p);
+
+	i = -1;
+	while ((i = find_next_bit(node_map, O2NM_MAX_NODES,
+				  i + 1)) < O2NM_MAX_NODES) {
+		if (i == dlm->node_num)
+			continue;
+
+		mlog(0, "Sending regions to node %d\n", i);
+
+		ret = o2net_send_message(DLM_QUERY_REGION, DLM_MOD_KEY, qr,
+					 sizeof(struct dlm_query_region),
+					 i, &status);
+		if (ret >= 0)
+			ret = status;
+		if (ret) {
+			mlog(ML_ERROR, "Region mismatch %d, node %d\n",
+			     ret, i);
+			break;
+		}
+	}
+
+bail:
+	kfree(qr);
+	return ret;
+}
+
+static int dlm_query_region_handler(struct o2net_msg *msg, u32 len,
+				    void *data, void **ret_data)
+{
+	struct dlm_query_region *qr;
+	struct dlm_ctxt *dlm = NULL;
+	char *local = NULL;
+	int status = 0;
+
+	qr = (struct dlm_query_region *) msg->buf;
+
+	mlog(0, "Node %u queries hb regions on domain %s\n", qr->qr_node,
+	     qr->qr_domain);
+
+	/* buffer used in dlm_mast_regions() */
+	local = kmalloc(sizeof(qr->qr_regions), GFP_KERNEL);
+	if (!local)
+		return -ENOMEM;
+
+	status = -EINVAL;
+
+	spin_lock(&dlm_domain_lock);
+	dlm = __dlm_lookup_domain_full(qr->qr_domain, qr->qr_namelen);
+	if (!dlm) {
+		mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
+		     "before join domain\n", qr->qr_node, qr->qr_domain);
+		goto out_domain_lock;
+	}
+
+	spin_lock(&dlm->spinlock);
+	if (dlm->joining_node != qr->qr_node) {
+		mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
+		     "but joining node is %d\n", qr->qr_node, qr->qr_domain,
+		     dlm->joining_node);
+		goto out_dlm_lock;
+	}
+
+	/* Support for global heartbeat was added in 1.1 */
+	if (dlm->dlm_locking_proto.pv_major == 1 &&
+	    dlm->dlm_locking_proto.pv_minor == 0) {
+		mlog(ML_ERROR, "Node %d queried hb regions on domain %s "
+		     "but active dlm protocol is %d.%d\n", qr->qr_node,
+		     qr->qr_domain, dlm->dlm_locking_proto.pv_major,
+		     dlm->dlm_locking_proto.pv_minor);
+		goto out_dlm_lock;
+	}
+
+	status = dlm_match_regions(dlm, qr, local, sizeof(qr->qr_regions));
+
+out_dlm_lock:
+	spin_unlock(&dlm->spinlock);
+
+out_domain_lock:
+	spin_unlock(&dlm_domain_lock);
+
+	kfree(local);
+
+	return status;
+}
+
+static int dlm_match_nodes(struct dlm_ctxt *dlm, struct dlm_query_nodeinfo *qn)
+{
+	struct o2nm_node *local;
+	struct dlm_node_info *remote;
+	int i, j;
+	int status = 0;
+
+	for (j = 0; j < qn->qn_numnodes; ++j)
+		mlog(0, "Node %3d, %pI4:%u\n", qn->qn_nodes[j].ni_nodenum,
+		     &(qn->qn_nodes[j].ni_ipv4_address),
+		     ntohs(qn->qn_nodes[j].ni_ipv4_port));
+
+	for (i = 0; i < O2NM_MAX_NODES && !status; ++i) {
+		local = o2nm_get_node_by_num(i);
+		remote = NULL;
+		for (j = 0; j < qn->qn_numnodes; ++j) {
+			if (qn->qn_nodes[j].ni_nodenum == i) {
+				remote = &(qn->qn_nodes[j]);
+				break;
+			}
+		}
+
+		if (!local && !remote)
+			continue;
+
+		if ((local && !remote) || (!local && remote))
+			status = -EINVAL;
+
+		if (!status &&
+		    ((remote->ni_nodenum != local->nd_num) ||
+		     (remote->ni_ipv4_port != local->nd_ipv4_port) ||
+		     (remote->ni_ipv4_address != local->nd_ipv4_address)))
+			status = -EINVAL;
+
+		if (status) {
+			if (remote && !local)
+				mlog(ML_ERROR, "Domain %s: Node %d (%pI4:%u) "
+				     "registered in joining node %d but not in "
+				     "local node %d\n", qn->qn_domain,
+				     remote->ni_nodenum,
+				     &(remote->ni_ipv4_address),
+				     ntohs(remote->ni_ipv4_port),
+				     qn->qn_nodenum, dlm->node_num);
+			if (local && !remote)
+				mlog(ML_ERROR, "Domain %s: Node %d (%pI4:%u) "
+				     "registered in local node %d but not in "
+				     "joining node %d\n", qn->qn_domain,
+				     local->nd_num, &(local->nd_ipv4_address),
+				     ntohs(local->nd_ipv4_port),
+				     dlm->node_num, qn->qn_nodenum);
+			BUG_ON((!local && !remote));
+		}
+
+		if (local)
+			o2nm_node_put(local);
+	}
+
+	return status;
+}
+
+static int dlm_send_nodeinfo(struct dlm_ctxt *dlm, unsigned long *node_map)
+{
+	struct dlm_query_nodeinfo *qn = NULL;
+	struct o2nm_node *node;
+	int ret = 0, status, count, i;
+
+	if (find_first_bit(node_map, O2NM_MAX_NODES) >= O2NM_MAX_NODES)
+		goto bail;
+
+	qn = kzalloc(sizeof(struct dlm_query_nodeinfo), GFP_KERNEL);
+	if (!qn) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	for (i = 0, count = 0; i < O2NM_MAX_NODES; ++i) {
+		node = o2nm_get_node_by_num(i);
+		if (!node)
+			continue;
+		qn->qn_nodes[count].ni_nodenum = node->nd_num;
+		qn->qn_nodes[count].ni_ipv4_port = node->nd_ipv4_port;
+		qn->qn_nodes[count].ni_ipv4_address = node->nd_ipv4_address;
+		mlog(0, "Node %3d, %pI4:%u\n", node->nd_num,
+		     &(node->nd_ipv4_address), ntohs(node->nd_ipv4_port));
+		++count;
+		o2nm_node_put(node);
+	}
+
+	qn->qn_nodenum = dlm->node_num;
+	qn->qn_numnodes = count;
+	qn->qn_namelen = strlen(dlm->name);
+	memcpy(qn->qn_domain, dlm->name, qn->qn_namelen);
+
+	i = -1;
+	while ((i = find_next_bit(node_map, O2NM_MAX_NODES,
+				  i + 1)) < O2NM_MAX_NODES) {
+		if (i == dlm->node_num)
+			continue;
+
+		mlog(0, "Sending nodeinfo to node %d\n", i);
+
+		ret = o2net_send_message(DLM_QUERY_NODEINFO, DLM_MOD_KEY,
+					 qn, sizeof(struct dlm_query_nodeinfo),
+					 i, &status);
+		if (ret >= 0)
+			ret = status;
+		if (ret) {
+			mlog(ML_ERROR, "node mismatch %d, node %d\n", ret, i);
+			break;
+		}
+	}
+
+bail:
+	kfree(qn);
+	return ret;
+}
+
+static int dlm_query_nodeinfo_handler(struct o2net_msg *msg, u32 len,
+				      void *data, void **ret_data)
+{
+	struct dlm_query_nodeinfo *qn;
+	struct dlm_ctxt *dlm = NULL;
+	int locked = 0, status = -EINVAL;
+
+	qn = (struct dlm_query_nodeinfo *) msg->buf;
+
+	mlog(0, "Node %u queries nodes on domain %s\n", qn->qn_nodenum,
+	     qn->qn_domain);
+
+	spin_lock(&dlm_domain_lock);
+	dlm = __dlm_lookup_domain_full(qn->qn_domain, qn->qn_namelen);
+	if (!dlm) {
+		mlog(ML_ERROR, "Node %d queried nodes on domain %s before "
+		     "join domain\n", qn->qn_nodenum, qn->qn_domain);
+		goto bail;
+	}
+
+	spin_lock(&dlm->spinlock);
+	locked = 1;
+	if (dlm->joining_node != qn->qn_nodenum) {
+		mlog(ML_ERROR, "Node %d queried nodes on domain %s but "
+		     "joining node is %d\n", qn->qn_nodenum, qn->qn_domain,
+		     dlm->joining_node);
+		goto bail;
+	}
+
+	/* Support for node query was added in 1.1 */
+	if (dlm->dlm_locking_proto.pv_major == 1 &&
+	    dlm->dlm_locking_proto.pv_minor == 0) {
+		mlog(ML_ERROR, "Node %d queried nodes on domain %s "
+		     "but active dlm protocol is %d.%d\n", qn->qn_nodenum,
+		     qn->qn_domain, dlm->dlm_locking_proto.pv_major,
+		     dlm->dlm_locking_proto.pv_minor);
+		goto bail;
+	}
+
+	status = dlm_match_nodes(dlm, qn);
+
+bail:
+	if (locked)
+		spin_unlock(&dlm->spinlock);
+	spin_unlock(&dlm_domain_lock);
+
+	return status;
+}
+
+static int dlm_cancel_join_handler(struct o2net_msg *msg, u32 len, void *data,
+				   void **ret_data)
+{
+	struct dlm_cancel_join *cancel;
+	struct dlm_ctxt *dlm = NULL;
+
+	cancel = (struct dlm_cancel_join *) msg->buf;
+
+	mlog(0, "node %u cancels join on domain %s\n", cancel->node_idx,
+		  cancel->domain);
+
+	spin_lock(&dlm_domain_lock);
+	dlm = __dlm_lookup_domain_full(cancel->domain, cancel->name_len);
+
+	if (dlm) {
+		spin_lock(&dlm->spinlock);
+
+		/* Yikes, this guy wants to cancel his join. No
+		 * problem, we simply cleanup our join state. */
+		BUG_ON(dlm->joining_node != cancel->node_idx);
+		__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+
+		spin_unlock(&dlm->spinlock);
+	}
+	spin_unlock(&dlm_domain_lock);
+
+	return 0;
+}
+
+static int dlm_send_one_join_cancel(struct dlm_ctxt *dlm,
+				    unsigned int node)
+{
+	int status;
+	struct dlm_cancel_join cancel_msg;
+
+	memset(&cancel_msg, 0, sizeof(cancel_msg));
+	cancel_msg.node_idx = dlm->node_num;
+	cancel_msg.name_len = strlen(dlm->name);
+	memcpy(cancel_msg.domain, dlm->name, cancel_msg.name_len);
+
+	status = o2net_send_message(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
+				    &cancel_msg, sizeof(cancel_msg), node,
+				    NULL);
+	if (status < 0) {
+		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
+		     "node %u\n", status, DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
+		     node);
+		goto bail;
+	}
+
+bail:
+	return status;
+}
+
+/* map_size should be in bytes. */
+static int dlm_send_join_cancels(struct dlm_ctxt *dlm,
+				 unsigned long *node_map,
+				 unsigned int map_size)
+{
+	int status, tmpstat;
+	int node;
+
+	if (map_size != (BITS_TO_LONGS(O2NM_MAX_NODES) *
+			 sizeof(unsigned long))) {
+		mlog(ML_ERROR,
+		     "map_size %u != BITS_TO_LONGS(O2NM_MAX_NODES) %u\n",
+		     map_size, (unsigned)BITS_TO_LONGS(O2NM_MAX_NODES));
+		return -EINVAL;
+	}
+
+	status = 0;
+	node = -1;
+	while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
+				     node + 1)) < O2NM_MAX_NODES) {
+		if (node == dlm->node_num)
+			continue;
+
+		tmpstat = dlm_send_one_join_cancel(dlm, node);
+		if (tmpstat) {
+			mlog(ML_ERROR, "Error return %d cancelling join on "
+			     "node %d\n", tmpstat, node);
+			if (!status)
+				status = tmpstat;
+		}
+	}
+
+	if (status)
+		mlog_errno(status);
+	return status;
+}
+
+static int dlm_request_join(struct dlm_ctxt *dlm,
+			    int node,
+			    enum dlm_query_join_response_code *response)
+{
+	int status;
+	struct dlm_query_join_request join_msg;
+	struct dlm_query_join_packet packet;
+	u32 join_resp;
+
+	mlog(0, "querying node %d\n", node);
+
+	memset(&join_msg, 0, sizeof(join_msg));
+	join_msg.node_idx = dlm->node_num;
+	join_msg.name_len = strlen(dlm->name);
+	memcpy(join_msg.domain, dlm->name, join_msg.name_len);
+	join_msg.dlm_proto = dlm->dlm_locking_proto;
+	join_msg.fs_proto = dlm->fs_locking_proto;
+
+	/* copy live node map to join message */
+	byte_copymap(join_msg.node_map, dlm->live_nodes_map, O2NM_MAX_NODES);
+
+	status = o2net_send_message(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY, &join_msg,
+				    sizeof(join_msg), node, &join_resp);
+	if (status < 0 && status != -ENOPROTOOPT) {
+		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
+		     "node %u\n", status, DLM_QUERY_JOIN_MSG, DLM_MOD_KEY,
+		     node);
+		goto bail;
+	}
+	dlm_query_join_wire_to_packet(join_resp, &packet);
+
+	/* -ENOPROTOOPT from the net code means the other side isn't
+	    listening for our message type -- that's fine, it means
+	    his dlm isn't up, so we can consider him a 'yes' but not
+	    joined into the domain.  */
+	if (status == -ENOPROTOOPT) {
+		status = 0;
+		*response = JOIN_OK_NO_MAP;
+	} else {
+		*response = packet.code;
+		switch (packet.code) {
+		case JOIN_DISALLOW:
+		case JOIN_OK_NO_MAP:
+			break;
+		case JOIN_PROTOCOL_MISMATCH:
+			mlog(ML_NOTICE,
+			     "This node requested DLM locking protocol %u.%u and "
+			     "filesystem locking protocol %u.%u.  At least one of "
+			     "the protocol versions on node %d is not compatible, "
+			     "disconnecting\n",
+			     dlm->dlm_locking_proto.pv_major,
+			     dlm->dlm_locking_proto.pv_minor,
+			     dlm->fs_locking_proto.pv_major,
+			     dlm->fs_locking_proto.pv_minor,
+			     node);
+			status = -EPROTO;
+			break;
+		case JOIN_OK:
+			/* Use the same locking protocol as the remote node */
+			dlm->dlm_locking_proto.pv_minor = packet.dlm_minor;
+			dlm->fs_locking_proto.pv_minor = packet.fs_minor;
+			mlog(0,
+			     "Node %d responds JOIN_OK with DLM locking protocol "
+			     "%u.%u and fs locking protocol %u.%u\n",
+			     node,
+			     dlm->dlm_locking_proto.pv_major,
+			     dlm->dlm_locking_proto.pv_minor,
+			     dlm->fs_locking_proto.pv_major,
+			     dlm->fs_locking_proto.pv_minor);
+			break;
+		default:
+			status = -EINVAL;
+			mlog(ML_ERROR, "invalid response %d from node %u\n",
+			     packet.code, node);
+			/* Reset response to JOIN_DISALLOW */
+			*response = JOIN_DISALLOW;
+			break;
+		}
+	}
+
+	mlog(0, "status %d, node %d response is %d\n", status, node,
+	     *response);
+
+bail:
+	return status;
+}
+
+static int dlm_send_one_join_assert(struct dlm_ctxt *dlm,
+				    unsigned int node)
+{
+	int status;
+	int ret;
+	struct dlm_assert_joined assert_msg;
+
+	mlog(0, "Sending join assert to node %u\n", node);
+
+	memset(&assert_msg, 0, sizeof(assert_msg));
+	assert_msg.node_idx = dlm->node_num;
+	assert_msg.name_len = strlen(dlm->name);
+	memcpy(assert_msg.domain, dlm->name, assert_msg.name_len);
+
+	status = o2net_send_message(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
+				    &assert_msg, sizeof(assert_msg), node,
+				    &ret);
+	if (status < 0)
+		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
+		     "node %u\n", status, DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
+		     node);
+	else
+		status = ret;
+
+	return status;
+}
+
+static void dlm_send_join_asserts(struct dlm_ctxt *dlm,
+				  unsigned long *node_map)
+{
+	int status, node, live;
+
+	status = 0;
+	node = -1;
+	while ((node = find_next_bit(node_map, O2NM_MAX_NODES,
+				     node + 1)) < O2NM_MAX_NODES) {
+		if (node == dlm->node_num)
+			continue;
+
+		do {
+			/* It is very important that this message be
+			 * received so we spin until either the node
+			 * has died or it gets the message. */
+			status = dlm_send_one_join_assert(dlm, node);
+
+			spin_lock(&dlm->spinlock);
+			live = test_bit(node, dlm->live_nodes_map);
+			spin_unlock(&dlm->spinlock);
+
+			if (status) {
+				mlog(ML_ERROR, "Error return %d asserting "
+				     "join on node %d\n", status, node);
+
+				/* give us some time between errors... */
+				if (live)
+					msleep(DLM_DOMAIN_BACKOFF_MS);
+			}
+		} while (status && live);
+	}
+}
+
+struct domain_join_ctxt {
+	unsigned long live_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long yes_resp_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+};
+
+static int dlm_should_restart_join(struct dlm_ctxt *dlm,
+				   struct domain_join_ctxt *ctxt,
+				   enum dlm_query_join_response_code response)
+{
+	int ret;
+
+	if (response == JOIN_DISALLOW) {
+		mlog(0, "Latest response of disallow -- should restart\n");
+		return 1;
+	}
+
+	spin_lock(&dlm->spinlock);
+	/* For now, we restart the process if the node maps have
+	 * changed at all */
+	ret = memcmp(ctxt->live_map, dlm->live_nodes_map,
+		     sizeof(dlm->live_nodes_map));
+	spin_unlock(&dlm->spinlock);
+
+	if (ret)
+		mlog(0, "Node maps changed -- should restart\n");
+
+	return ret;
+}
+
+static int dlm_try_to_join_domain(struct dlm_ctxt *dlm)
+{
+	int status = 0, tmpstat, node;
+	struct domain_join_ctxt *ctxt;
+	enum dlm_query_join_response_code response = JOIN_DISALLOW;
+
+	mlog(0, "%p", dlm);
+
+	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
+	if (!ctxt) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* group sem locking should work for us here -- we're already
+	 * registered for heartbeat events so filling this should be
+	 * atomic wrt getting those handlers called. */
+	o2hb_fill_node_map(dlm->live_nodes_map, sizeof(dlm->live_nodes_map));
+
+	spin_lock(&dlm->spinlock);
+	memcpy(ctxt->live_map, dlm->live_nodes_map, sizeof(ctxt->live_map));
+
+	__dlm_set_joining_node(dlm, dlm->node_num);
+
+	spin_unlock(&dlm->spinlock);
+
+	node = -1;
+	while ((node = find_next_bit(ctxt->live_map, O2NM_MAX_NODES,
+				     node + 1)) < O2NM_MAX_NODES) {
+		if (node == dlm->node_num)
+			continue;
+
+		status = dlm_request_join(dlm, node, &response);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		/* Ok, either we got a response or the node doesn't have a
+		 * dlm up. */
+		if (response == JOIN_OK)
+			set_bit(node, ctxt->yes_resp_map);
+
+		if (dlm_should_restart_join(dlm, ctxt, response)) {
+			status = -EAGAIN;
+			goto bail;
+		}
+	}
+
+	mlog(0, "Yay, done querying nodes!\n");
+
+	/* Yay, everyone agree's we can join the domain. My domain is
+	 * comprised of all nodes who were put in the
+	 * yes_resp_map. Copy that into our domain map and send a join
+	 * assert message to clean up everyone elses state. */
+	spin_lock(&dlm->spinlock);
+	memcpy(dlm->domain_map, ctxt->yes_resp_map,
+	       sizeof(ctxt->yes_resp_map));
+	set_bit(dlm->node_num, dlm->domain_map);
+	spin_unlock(&dlm->spinlock);
+
+	/* Support for global heartbeat and node info was added in 1.1 */
+	if (dlm->dlm_locking_proto.pv_major > 1 ||
+	    dlm->dlm_locking_proto.pv_minor > 0) {
+		status = dlm_send_nodeinfo(dlm, ctxt->yes_resp_map);
+		if (status) {
+			mlog_errno(status);
+			goto bail;
+		}
+		status = dlm_send_regions(dlm, ctxt->yes_resp_map);
+		if (status) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+	dlm_send_join_asserts(dlm, ctxt->yes_resp_map);
+
+	/* Joined state *must* be set before the joining node
+	 * information, otherwise the query_join handler may read no
+	 * current joiner but a state of NEW and tell joining nodes
+	 * we're not in the domain. */
+	spin_lock(&dlm_domain_lock);
+	dlm->dlm_state = DLM_CTXT_JOINED;
+	dlm->num_joins++;
+	spin_unlock(&dlm_domain_lock);
+
+bail:
+	spin_lock(&dlm->spinlock);
+	__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+	if (!status) {
+		printk(KERN_NOTICE "o2dlm: Joining domain %s ", dlm->name);
+		__dlm_print_nodes(dlm);
+	}
+	spin_unlock(&dlm->spinlock);
+
+	if (ctxt) {
+		/* Do we need to send a cancel message to any nodes? */
+		if (status < 0) {
+			tmpstat = dlm_send_join_cancels(dlm,
+							ctxt->yes_resp_map,
+							sizeof(ctxt->yes_resp_map));
+			if (tmpstat < 0)
+				mlog_errno(tmpstat);
+		}
+		kfree(ctxt);
+	}
+
+	mlog(0, "returning %d\n", status);
+	return status;
+}
+
+static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm)
+{
+	o2hb_unregister_callback(dlm->name, &dlm->dlm_hb_up);
+	o2hb_unregister_callback(dlm->name, &dlm->dlm_hb_down);
+	o2net_unregister_handler_list(&dlm->dlm_domain_handlers);
+}
+
+static int dlm_register_domain_handlers(struct dlm_ctxt *dlm)
+{
+	int status;
+
+	mlog(0, "registering handlers.\n");
+
+	o2hb_setup_callback(&dlm->dlm_hb_down, O2HB_NODE_DOWN_CB,
+			    dlm_hb_node_down_cb, dlm, DLM_HB_NODE_DOWN_PRI);
+	o2hb_setup_callback(&dlm->dlm_hb_up, O2HB_NODE_UP_CB,
+			    dlm_hb_node_up_cb, dlm, DLM_HB_NODE_UP_PRI);
+
+	status = o2hb_register_callback(dlm->name, &dlm->dlm_hb_down);
+	if (status)
+		goto bail;
+
+	status = o2hb_register_callback(dlm->name, &dlm->dlm_hb_up);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_MASTER_REQUEST_MSG, dlm->key,
+					sizeof(struct dlm_master_request),
+					dlm_master_request_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_ASSERT_MASTER_MSG, dlm->key,
+					sizeof(struct dlm_assert_master),
+					dlm_assert_master_handler,
+					dlm, dlm_assert_master_post_handler,
+					&dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_CREATE_LOCK_MSG, dlm->key,
+					sizeof(struct dlm_create_lock),
+					dlm_create_lock_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_CONVERT_LOCK_MSG, dlm->key,
+					DLM_CONVERT_LOCK_MAX_LEN,
+					dlm_convert_lock_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_UNLOCK_LOCK_MSG, dlm->key,
+					DLM_UNLOCK_LOCK_MAX_LEN,
+					dlm_unlock_lock_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_PROXY_AST_MSG, dlm->key,
+					DLM_PROXY_AST_MAX_LEN,
+					dlm_proxy_ast_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_EXIT_DOMAIN_MSG, dlm->key,
+					sizeof(struct dlm_exit_domain),
+					dlm_exit_domain_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_DEREF_LOCKRES_MSG, dlm->key,
+					sizeof(struct dlm_deref_lockres),
+					dlm_deref_lockres_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_MIGRATE_REQUEST_MSG, dlm->key,
+					sizeof(struct dlm_migrate_request),
+					dlm_migrate_request_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_MIG_LOCKRES_MSG, dlm->key,
+					DLM_MIG_LOCKRES_MAX_LEN,
+					dlm_mig_lockres_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_MASTER_REQUERY_MSG, dlm->key,
+					sizeof(struct dlm_master_requery),
+					dlm_master_requery_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_LOCK_REQUEST_MSG, dlm->key,
+					sizeof(struct dlm_lock_request),
+					dlm_request_all_locks_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_RECO_DATA_DONE_MSG, dlm->key,
+					sizeof(struct dlm_reco_data_done),
+					dlm_reco_data_done_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_BEGIN_RECO_MSG, dlm->key,
+					sizeof(struct dlm_begin_reco),
+					dlm_begin_reco_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_FINALIZE_RECO_MSG, dlm->key,
+					sizeof(struct dlm_finalize_reco),
+					dlm_finalize_reco_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_BEGIN_EXIT_DOMAIN_MSG, dlm->key,
+					sizeof(struct dlm_exit_domain),
+					dlm_begin_exit_domain_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_DEREF_LOCKRES_DONE, dlm->key,
+					sizeof(struct dlm_deref_lockres_done),
+					dlm_deref_lockres_done_handler,
+					dlm, NULL, &dlm->dlm_domain_handlers);
+bail:
+	if (status)
+		dlm_unregister_domain_handlers(dlm);
+
+	return status;
+}
+
+static int dlm_join_domain(struct dlm_ctxt *dlm)
+{
+	int status;
+	unsigned int backoff;
+	unsigned int total_backoff = 0;
+	char wq_name[O2NM_MAX_NAME_LEN];
+
+	BUG_ON(!dlm);
+
+	mlog(0, "Join domain %s\n", dlm->name);
+
+	status = dlm_register_domain_handlers(dlm);
+	if (status) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = dlm_launch_thread(dlm);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = dlm_launch_recovery_thread(dlm);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	dlm_debug_init(dlm);
+
+	snprintf(wq_name, O2NM_MAX_NAME_LEN, "dlm_wq-%s", dlm->name);
+	dlm->dlm_worker = alloc_workqueue(wq_name, WQ_MEM_RECLAIM, 0);
+	if (!dlm->dlm_worker) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	do {
+		status = dlm_try_to_join_domain(dlm);
+
+		/* If we're racing another node to the join, then we
+		 * need to back off temporarily and let them
+		 * complete. */
+#define	DLM_JOIN_TIMEOUT_MSECS	90000
+		if (status == -EAGAIN) {
+			if (signal_pending(current)) {
+				status = -ERESTARTSYS;
+				goto bail;
+			}
+
+			if (total_backoff > DLM_JOIN_TIMEOUT_MSECS) {
+				status = -ERESTARTSYS;
+				mlog(ML_NOTICE, "Timed out joining dlm domain "
+				     "%s after %u msecs\n", dlm->name,
+				     total_backoff);
+				goto bail;
+			}
+
+			/*
+			 * <chip> After you!
+			 * <dale> No, after you!
+			 * <chip> I insist!
+			 * <dale> But you first!
+			 * ...
+			 */
+			backoff = (unsigned int)(jiffies & 0x3);
+			backoff *= DLM_DOMAIN_BACKOFF_MS;
+			total_backoff += backoff;
+			mlog(0, "backoff %d\n", backoff);
+			msleep(backoff);
+		}
+	} while (status == -EAGAIN);
+
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = 0;
+bail:
+	wake_up(&dlm_domain_events);
+
+	if (status) {
+		dlm_unregister_domain_handlers(dlm);
+		dlm_complete_thread(dlm);
+		dlm_complete_recovery_thread(dlm);
+		dlm_destroy_dlm_worker(dlm);
+	}
+
+	return status;
+}
+
+static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
+				u32 key)
+{
+	int i;
+	int ret;
+	struct dlm_ctxt *dlm = NULL;
+
+	dlm = kzalloc(sizeof(*dlm), GFP_KERNEL);
+	if (!dlm) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	dlm->name = kstrdup(domain, GFP_KERNEL);
+	if (dlm->name == NULL) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	dlm->lockres_hash = (struct hlist_head **)dlm_alloc_pagevec(DLM_HASH_PAGES);
+	if (!dlm->lockres_hash) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	for (i = 0; i < DLM_HASH_BUCKETS; i++)
+		INIT_HLIST_HEAD(dlm_lockres_hash(dlm, i));
+
+	dlm->master_hash = (struct hlist_head **)
+				dlm_alloc_pagevec(DLM_HASH_PAGES);
+	if (!dlm->master_hash) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	for (i = 0; i < DLM_HASH_BUCKETS; i++)
+		INIT_HLIST_HEAD(dlm_master_hash(dlm, i));
+
+	dlm->key = key;
+	dlm->node_num = o2nm_this_node();
+
+	dlm_create_debugfs_subroot(dlm);
+
+	spin_lock_init(&dlm->spinlock);
+	spin_lock_init(&dlm->master_lock);
+	spin_lock_init(&dlm->ast_lock);
+	spin_lock_init(&dlm->track_lock);
+	INIT_LIST_HEAD(&dlm->list);
+	INIT_LIST_HEAD(&dlm->dirty_list);
+	INIT_LIST_HEAD(&dlm->reco.resources);
+	INIT_LIST_HEAD(&dlm->reco.node_data);
+	INIT_LIST_HEAD(&dlm->purge_list);
+	INIT_LIST_HEAD(&dlm->dlm_domain_handlers);
+	INIT_LIST_HEAD(&dlm->tracking_list);
+	dlm->reco.state = 0;
+
+	INIT_LIST_HEAD(&dlm->pending_asts);
+	INIT_LIST_HEAD(&dlm->pending_basts);
+
+	mlog(0, "dlm->recovery_map=%p, &(dlm->recovery_map[0])=%p\n",
+		  dlm->recovery_map, &(dlm->recovery_map[0]));
+
+	memset(dlm->recovery_map, 0, sizeof(dlm->recovery_map));
+	memset(dlm->live_nodes_map, 0, sizeof(dlm->live_nodes_map));
+	memset(dlm->domain_map, 0, sizeof(dlm->domain_map));
+
+	dlm->dlm_thread_task = NULL;
+	dlm->dlm_reco_thread_task = NULL;
+	dlm->dlm_worker = NULL;
+	init_waitqueue_head(&dlm->dlm_thread_wq);
+	init_waitqueue_head(&dlm->dlm_reco_thread_wq);
+	init_waitqueue_head(&dlm->reco.event);
+	init_waitqueue_head(&dlm->ast_wq);
+	init_waitqueue_head(&dlm->migration_wq);
+	INIT_LIST_HEAD(&dlm->mle_hb_events);
+
+	dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
+	init_waitqueue_head(&dlm->dlm_join_events);
+
+	dlm->migrate_done = 0;
+
+	dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
+	dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
+
+	atomic_set(&dlm->res_tot_count, 0);
+	atomic_set(&dlm->res_cur_count, 0);
+	for (i = 0; i < DLM_MLE_NUM_TYPES; ++i) {
+		atomic_set(&dlm->mle_tot_count[i], 0);
+		atomic_set(&dlm->mle_cur_count[i], 0);
+	}
+
+	spin_lock_init(&dlm->work_lock);
+	INIT_LIST_HEAD(&dlm->work_list);
+	INIT_WORK(&dlm->dispatched_work, dlm_dispatch_work);
+
+	kref_init(&dlm->dlm_refs);
+	dlm->dlm_state = DLM_CTXT_NEW;
+
+	INIT_LIST_HEAD(&dlm->dlm_eviction_callbacks);
+
+	mlog(0, "context init: refcount %u\n",
+		  kref_read(&dlm->dlm_refs));
+
+	ret = 0;
+leave:
+	if (ret < 0 && dlm) {
+		if (dlm->master_hash)
+			dlm_free_pagevec((void **)dlm->master_hash,
+					DLM_HASH_PAGES);
+
+		if (dlm->lockres_hash)
+			dlm_free_pagevec((void **)dlm->lockres_hash,
+					DLM_HASH_PAGES);
+
+		kfree(dlm->name);
+		kfree(dlm);
+		dlm = NULL;
+	}
+	return dlm;
+}
+
+/*
+ * Compare a requested locking protocol version against the current one.
+ *
+ * If the major numbers are different, they are incompatible.
+ * If the current minor is greater than the request, they are incompatible.
+ * If the current minor is less than or equal to the request, they are
+ * compatible, and the requester should run at the current minor version.
+ */
+static int dlm_protocol_compare(struct dlm_protocol_version *existing,
+				struct dlm_protocol_version *request)
+{
+	if (existing->pv_major != request->pv_major)
+		return 1;
+
+	if (existing->pv_minor > request->pv_minor)
+		return 1;
+
+	if (existing->pv_minor < request->pv_minor)
+		request->pv_minor = existing->pv_minor;
+
+	return 0;
+}
+
+/*
+ * dlm_register_domain: one-time setup per "domain".
+ *
+ * The filesystem passes in the requested locking version via proto.
+ * If registration was successful, proto will contain the negotiated
+ * locking protocol.
+ */
+struct dlm_ctxt * dlm_register_domain(const char *domain,
+			       u32 key,
+			       struct dlm_protocol_version *fs_proto)
+{
+	int ret;
+	struct dlm_ctxt *dlm = NULL;
+	struct dlm_ctxt *new_ctxt = NULL;
+
+	if (strlen(domain) >= O2NM_MAX_NAME_LEN) {
+		ret = -ENAMETOOLONG;
+		mlog(ML_ERROR, "domain name length too long\n");
+		goto leave;
+	}
+
+	mlog(0, "register called for domain \"%s\"\n", domain);
+
+retry:
+	dlm = NULL;
+	if (signal_pending(current)) {
+		ret = -ERESTARTSYS;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	spin_lock(&dlm_domain_lock);
+
+	dlm = __dlm_lookup_domain(domain);
+	if (dlm) {
+		if (dlm->dlm_state != DLM_CTXT_JOINED) {
+			spin_unlock(&dlm_domain_lock);
+
+			mlog(0, "This ctxt is not joined yet!\n");
+			wait_event_interruptible(dlm_domain_events,
+						 dlm_wait_on_domain_helper(
+							 domain));
+			goto retry;
+		}
+
+		if (dlm_protocol_compare(&dlm->fs_locking_proto, fs_proto)) {
+			spin_unlock(&dlm_domain_lock);
+			mlog(ML_ERROR,
+			     "Requested locking protocol version is not "
+			     "compatible with already registered domain "
+			     "\"%s\"\n", domain);
+			ret = -EPROTO;
+			goto leave;
+		}
+
+		__dlm_get(dlm);
+		dlm->num_joins++;
+
+		spin_unlock(&dlm_domain_lock);
+
+		ret = 0;
+		goto leave;
+	}
+
+	/* doesn't exist */
+	if (!new_ctxt) {
+		spin_unlock(&dlm_domain_lock);
+
+		new_ctxt = dlm_alloc_ctxt(domain, key);
+		if (new_ctxt)
+			goto retry;
+
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	/* a little variable switch-a-roo here... */
+	dlm = new_ctxt;
+	new_ctxt = NULL;
+
+	/* add the new domain */
+	list_add_tail(&dlm->list, &dlm_domains);
+	spin_unlock(&dlm_domain_lock);
+
+	/*
+	 * Pass the locking protocol version into the join.  If the join
+	 * succeeds, it will have the negotiated protocol set.
+	 */
+	dlm->dlm_locking_proto = dlm_protocol;
+	dlm->fs_locking_proto = *fs_proto;
+
+	ret = dlm_join_domain(dlm);
+	if (ret) {
+		mlog_errno(ret);
+		dlm_put(dlm);
+		goto leave;
+	}
+
+	/* Tell the caller what locking protocol we negotiated */
+	*fs_proto = dlm->fs_locking_proto;
+
+	ret = 0;
+leave:
+	if (new_ctxt)
+		dlm_free_ctxt_mem(new_ctxt);
+
+	if (ret < 0)
+		dlm = ERR_PTR(ret);
+
+	return dlm;
+}
+EXPORT_SYMBOL_GPL(dlm_register_domain);
+
+static LIST_HEAD(dlm_join_handlers);
+
+static void dlm_unregister_net_handlers(void)
+{
+	o2net_unregister_handler_list(&dlm_join_handlers);
+}
+
+static int dlm_register_net_handlers(void)
+{
+	int status = 0;
+
+	status = o2net_register_handler(DLM_QUERY_JOIN_MSG, DLM_MOD_KEY,
+					sizeof(struct dlm_query_join_request),
+					dlm_query_join_handler,
+					NULL, NULL, &dlm_join_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_ASSERT_JOINED_MSG, DLM_MOD_KEY,
+					sizeof(struct dlm_assert_joined),
+					dlm_assert_joined_handler,
+					NULL, NULL, &dlm_join_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_CANCEL_JOIN_MSG, DLM_MOD_KEY,
+					sizeof(struct dlm_cancel_join),
+					dlm_cancel_join_handler,
+					NULL, NULL, &dlm_join_handlers);
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_QUERY_REGION, DLM_MOD_KEY,
+					sizeof(struct dlm_query_region),
+					dlm_query_region_handler,
+					NULL, NULL, &dlm_join_handlers);
+
+	if (status)
+		goto bail;
+
+	status = o2net_register_handler(DLM_QUERY_NODEINFO, DLM_MOD_KEY,
+					sizeof(struct dlm_query_nodeinfo),
+					dlm_query_nodeinfo_handler,
+					NULL, NULL, &dlm_join_handlers);
+bail:
+	if (status < 0)
+		dlm_unregister_net_handlers();
+
+	return status;
+}
+
+/* Domain eviction callback handling.
+ *
+ * The file system requires notification of node death *before* the
+ * dlm completes it's recovery work, otherwise it may be able to
+ * acquire locks on resources requiring recovery. Since the dlm can
+ * evict a node from it's domain *before* heartbeat fires, a similar
+ * mechanism is required. */
+
+/* Eviction is not expected to happen often, so a per-domain lock is
+ * not necessary. Eviction callbacks are allowed to sleep for short
+ * periods of time. */
+static DECLARE_RWSEM(dlm_callback_sem);
+
+void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
+					int node_num)
+{
+	struct dlm_eviction_cb *cb;
+
+	down_read(&dlm_callback_sem);
+	list_for_each_entry(cb, &dlm->dlm_eviction_callbacks, ec_item) {
+		cb->ec_func(node_num, cb->ec_data);
+	}
+	up_read(&dlm_callback_sem);
+}
+
+void dlm_setup_eviction_cb(struct dlm_eviction_cb *cb,
+			   dlm_eviction_func *f,
+			   void *data)
+{
+	INIT_LIST_HEAD(&cb->ec_item);
+	cb->ec_func = f;
+	cb->ec_data = data;
+}
+EXPORT_SYMBOL_GPL(dlm_setup_eviction_cb);
+
+void dlm_register_eviction_cb(struct dlm_ctxt *dlm,
+			      struct dlm_eviction_cb *cb)
+{
+	down_write(&dlm_callback_sem);
+	list_add_tail(&cb->ec_item, &dlm->dlm_eviction_callbacks);
+	up_write(&dlm_callback_sem);
+}
+EXPORT_SYMBOL_GPL(dlm_register_eviction_cb);
+
+void dlm_unregister_eviction_cb(struct dlm_eviction_cb *cb)
+{
+	down_write(&dlm_callback_sem);
+	list_del_init(&cb->ec_item);
+	up_write(&dlm_callback_sem);
+}
+EXPORT_SYMBOL_GPL(dlm_unregister_eviction_cb);
+
+static int __init dlm_init(void)
+{
+	int status;
+
+	status = dlm_init_mle_cache();
+	if (status) {
+		mlog(ML_ERROR, "Could not create o2dlm_mle slabcache\n");
+		goto error;
+	}
+
+	status = dlm_init_master_caches();
+	if (status) {
+		mlog(ML_ERROR, "Could not create o2dlm_lockres and "
+		     "o2dlm_lockname slabcaches\n");
+		goto error;
+	}
+
+	status = dlm_init_lock_cache();
+	if (status) {
+		mlog(ML_ERROR, "Count not create o2dlm_lock slabcache\n");
+		goto error;
+	}
+
+	status = dlm_register_net_handlers();
+	if (status) {
+		mlog(ML_ERROR, "Unable to register network handlers\n");
+		goto error;
+	}
+
+	dlm_create_debugfs_root();
+
+	return 0;
+error:
+	dlm_unregister_net_handlers();
+	dlm_destroy_lock_cache();
+	dlm_destroy_master_caches();
+	dlm_destroy_mle_cache();
+	return -1;
+}
+
+static void __exit dlm_exit (void)
+{
+	dlm_destroy_debugfs_root();
+	dlm_unregister_net_handlers();
+	dlm_destroy_lock_cache();
+	dlm_destroy_master_caches();
+	dlm_destroy_mle_cache();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("OCFS2 Distributed Lock Management");
+
+module_init(dlm_init);
+module_exit(dlm_exit);
diff --git a/fs/ocfs2/dlm/dlmdomain.h b/fs/ocfs2/dlm/dlmdomain.h
new file mode 100644
index 000000000..815abe30a
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdomain.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmdomain.h
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+#ifndef DLMDOMAIN_H
+#define DLMDOMAIN_H
+
+extern spinlock_t dlm_domain_lock;
+extern struct list_head dlm_domains;
+
+static inline int dlm_joined(struct dlm_ctxt *dlm)
+{
+	int ret = 0;
+
+	spin_lock(&dlm_domain_lock);
+	if (dlm->dlm_state == DLM_CTXT_JOINED)
+		ret = 1;
+	spin_unlock(&dlm_domain_lock);
+
+	return ret;
+}
+
+static inline int dlm_shutting_down(struct dlm_ctxt *dlm)
+{
+	int ret = 0;
+
+	spin_lock(&dlm_domain_lock);
+	if (dlm->dlm_state == DLM_CTXT_IN_SHUTDOWN)
+		ret = 1;
+	spin_unlock(&dlm_domain_lock);
+
+	return ret;
+}
+
+void dlm_fire_domain_eviction_callbacks(struct dlm_ctxt *dlm,
+					int node_num);
+
+#endif
diff --git a/fs/ocfs2/dlm/dlmlock.c b/fs/ocfs2/dlm/dlmlock.c
new file mode 100644
index 000000000..041fd1791
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmlock.c
@@ -0,0 +1,743 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmlock.c
+ *
+ * underlying calls for lock creation
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+
+#include "dlmconvert.h"
+
+#define MLOG_MASK_PREFIX ML_DLM
+#include "../cluster/masklog.h"
+
+static struct kmem_cache *dlm_lock_cache;
+
+static DEFINE_SPINLOCK(dlm_cookie_lock);
+static u64 dlm_next_cookie = 1;
+
+static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
+					       struct dlm_lock_resource *res,
+					       struct dlm_lock *lock, int flags);
+static void dlm_init_lock(struct dlm_lock *newlock, int type,
+			  u8 node, u64 cookie);
+static void dlm_lock_release(struct kref *kref);
+static void dlm_lock_detach_lockres(struct dlm_lock *lock);
+
+int dlm_init_lock_cache(void)
+{
+	dlm_lock_cache = kmem_cache_create("o2dlm_lock",
+					   sizeof(struct dlm_lock),
+					   0, SLAB_HWCACHE_ALIGN, NULL);
+	if (dlm_lock_cache == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void dlm_destroy_lock_cache(void)
+{
+	kmem_cache_destroy(dlm_lock_cache);
+}
+
+/* Tell us whether we can grant a new lock request.
+ * locking:
+ *   caller needs:  res->spinlock
+ *   taken:         none
+ *   held on exit:  none
+ * returns: 1 if the lock can be granted, 0 otherwise.
+ */
+static int dlm_can_grant_new_lock(struct dlm_lock_resource *res,
+				  struct dlm_lock *lock)
+{
+	struct dlm_lock *tmplock;
+
+	list_for_each_entry(tmplock, &res->granted, list) {
+		if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
+			return 0;
+	}
+
+	list_for_each_entry(tmplock, &res->converting, list) {
+		if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
+			return 0;
+		if (!dlm_lock_compatible(tmplock->ml.convert_type,
+					 lock->ml.type))
+			return 0;
+	}
+
+	return 1;
+}
+
+/* performs lock creation at the lockres master site
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_NOTQUEUED
+ */
+static enum dlm_status dlmlock_master(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res,
+				      struct dlm_lock *lock, int flags)
+{
+	int call_ast = 0, kick_thread = 0;
+	enum dlm_status status = DLM_NORMAL;
+
+	mlog(0, "type=%d\n", lock->ml.type);
+
+	spin_lock(&res->spinlock);
+	/* if called from dlm_create_lock_handler, need to
+	 * ensure it will not sleep in dlm_wait_on_lockres */
+	status = __dlm_lockres_state_to_status(res);
+	if (status != DLM_NORMAL &&
+	    lock->ml.node != dlm->node_num) {
+		/* erf.  state changed after lock was dropped. */
+		spin_unlock(&res->spinlock);
+		dlm_error(status);
+		return status;
+	}
+	__dlm_wait_on_lockres(res);
+	__dlm_lockres_reserve_ast(res);
+
+	if (dlm_can_grant_new_lock(res, lock)) {
+		mlog(0, "I can grant this lock right away\n");
+		/* got it right away */
+		lock->lksb->status = DLM_NORMAL;
+		status = DLM_NORMAL;
+		dlm_lock_get(lock);
+		list_add_tail(&lock->list, &res->granted);
+
+		/* for the recovery lock, we can't allow the ast
+		 * to be queued since the dlmthread is already
+		 * frozen.  but the recovery lock is always locked
+		 * with LKM_NOQUEUE so we do not need the ast in
+		 * this special case */
+		if (!dlm_is_recovery_lock(res->lockname.name,
+					  res->lockname.len)) {
+			kick_thread = 1;
+			call_ast = 1;
+		} else {
+			mlog(0, "%s: returning DLM_NORMAL to "
+			     "node %u for reco lock\n", dlm->name,
+			     lock->ml.node);
+		}
+	} else {
+		/* for NOQUEUE request, unless we get the
+		 * lock right away, return DLM_NOTQUEUED */
+		if (flags & LKM_NOQUEUE) {
+			status = DLM_NOTQUEUED;
+			if (dlm_is_recovery_lock(res->lockname.name,
+						 res->lockname.len)) {
+				mlog(0, "%s: returning NOTQUEUED to "
+				     "node %u for reco lock\n", dlm->name,
+				     lock->ml.node);
+			}
+		} else {
+			status = DLM_NORMAL;
+			dlm_lock_get(lock);
+			list_add_tail(&lock->list, &res->blocked);
+			kick_thread = 1;
+		}
+	}
+
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+	/* either queue the ast or release it */
+	if (call_ast)
+		dlm_queue_ast(dlm, lock);
+	else
+		dlm_lockres_release_ast(dlm, res);
+
+	dlm_lockres_calc_usage(dlm, res);
+	if (kick_thread)
+		dlm_kick_thread(dlm, res);
+
+	return status;
+}
+
+void dlm_revert_pending_lock(struct dlm_lock_resource *res,
+			     struct dlm_lock *lock)
+{
+	/* remove from local queue if it failed */
+	list_del_init(&lock->list);
+	lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
+}
+
+
+/*
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock
+ *   held on exit:  none
+ * returns: DLM_DENIED, DLM_RECOVERING, or net status
+ */
+static enum dlm_status dlmlock_remote(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res,
+				      struct dlm_lock *lock, int flags)
+{
+	enum dlm_status status = DLM_DENIED;
+	int lockres_changed = 1;
+
+	mlog(0, "type=%d, lockres %.*s, flags = 0x%x\n",
+	     lock->ml.type, res->lockname.len,
+	     res->lockname.name, flags);
+
+	/*
+	 * Wait if resource is getting recovered, remastered, etc.
+	 * If the resource was remastered and new owner is self, then exit.
+	 */
+	spin_lock(&res->spinlock);
+	__dlm_wait_on_lockres(res);
+	if (res->owner == dlm->node_num) {
+		spin_unlock(&res->spinlock);
+		return DLM_RECOVERING;
+	}
+	res->state |= DLM_LOCK_RES_IN_PROGRESS;
+
+	/* add lock to local (secondary) queue */
+	dlm_lock_get(lock);
+	list_add_tail(&lock->list, &res->blocked);
+	lock->lock_pending = 1;
+	spin_unlock(&res->spinlock);
+
+	/* spec seems to say that you will get DLM_NORMAL when the lock
+	 * has been queued, meaning we need to wait for a reply here. */
+	status = dlm_send_remote_lock_request(dlm, res, lock, flags);
+
+	spin_lock(&res->spinlock);
+	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+	lock->lock_pending = 0;
+	if (status != DLM_NORMAL) {
+		if (status == DLM_RECOVERING &&
+		    dlm_is_recovery_lock(res->lockname.name,
+					 res->lockname.len)) {
+			/* recovery lock was mastered by dead node.
+			 * we need to have calc_usage shoot down this
+			 * lockres and completely remaster it. */
+			mlog(0, "%s: recovery lock was owned by "
+			     "dead node %u, remaster it now.\n",
+			     dlm->name, res->owner);
+		} else if (status != DLM_NOTQUEUED) {
+			/*
+			 * DO NOT call calc_usage, as this would unhash
+			 * the remote lockres before we ever get to use
+			 * it.  treat as if we never made any change to
+			 * the lockres.
+			 */
+			lockres_changed = 0;
+			dlm_error(status);
+		}
+		dlm_revert_pending_lock(res, lock);
+		dlm_lock_put(lock);
+	} else if (dlm_is_recovery_lock(res->lockname.name,
+					res->lockname.len)) {
+		/* special case for the $RECOVERY lock.
+		 * there will never be an AST delivered to put
+		 * this lock on the proper secondary queue
+		 * (granted), so do it manually. */
+		mlog(0, "%s: $RECOVERY lock for this node (%u) is "
+		     "mastered by %u; got lock, manually granting (no ast)\n",
+		     dlm->name, dlm->node_num, res->owner);
+		list_move_tail(&lock->list, &res->granted);
+	}
+	spin_unlock(&res->spinlock);
+
+	if (lockres_changed)
+		dlm_lockres_calc_usage(dlm, res);
+
+	wake_up(&res->wq);
+	return status;
+}
+
+
+/* for remote lock creation.
+ * locking:
+ *   caller needs:  none, but need res->state & DLM_LOCK_RES_IN_PROGRESS
+ *   taken:         none
+ *   held on exit:  none
+ * returns: DLM_NOLOCKMGR, or net status
+ */
+static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
+					       struct dlm_lock_resource *res,
+					       struct dlm_lock *lock, int flags)
+{
+	struct dlm_create_lock create;
+	int tmpret, status = 0;
+	enum dlm_status ret;
+
+	memset(&create, 0, sizeof(create));
+	create.node_idx = dlm->node_num;
+	create.requested_type = lock->ml.type;
+	create.cookie = lock->ml.cookie;
+	create.namelen = res->lockname.len;
+	create.flags = cpu_to_be32(flags);
+	memcpy(create.name, res->lockname.name, create.namelen);
+
+	tmpret = o2net_send_message(DLM_CREATE_LOCK_MSG, dlm->key, &create,
+				    sizeof(create), res->owner, &status);
+	if (tmpret >= 0) {
+		ret = status;
+		if (ret == DLM_REJECTED) {
+			mlog(ML_ERROR, "%s: res %.*s, Stale lockres no longer "
+			     "owned by node %u. That node is coming back up "
+			     "currently.\n", dlm->name, create.namelen,
+			     create.name, res->owner);
+			dlm_print_one_lock_resource(res);
+			BUG();
+		}
+	} else {
+		mlog(ML_ERROR, "%s: res %.*s, Error %d send CREATE LOCK to "
+		     "node %u\n", dlm->name, create.namelen, create.name,
+		     tmpret, res->owner);
+		if (dlm_is_host_down(tmpret))
+			ret = DLM_RECOVERING;
+		else
+			ret = dlm_err_to_dlm_status(tmpret);
+	}
+
+	return ret;
+}
+
+void dlm_lock_get(struct dlm_lock *lock)
+{
+	kref_get(&lock->lock_refs);
+}
+
+void dlm_lock_put(struct dlm_lock *lock)
+{
+	kref_put(&lock->lock_refs, dlm_lock_release);
+}
+
+static void dlm_lock_release(struct kref *kref)
+{
+	struct dlm_lock *lock;
+
+	lock = container_of(kref, struct dlm_lock, lock_refs);
+
+	BUG_ON(!list_empty(&lock->list));
+	BUG_ON(!list_empty(&lock->ast_list));
+	BUG_ON(!list_empty(&lock->bast_list));
+	BUG_ON(lock->ast_pending);
+	BUG_ON(lock->bast_pending);
+
+	dlm_lock_detach_lockres(lock);
+
+	if (lock->lksb_kernel_allocated) {
+		mlog(0, "freeing kernel-allocated lksb\n");
+		kfree(lock->lksb);
+	}
+	kmem_cache_free(dlm_lock_cache, lock);
+}
+
+/* associate a lock with it's lockres, getting a ref on the lockres */
+void dlm_lock_attach_lockres(struct dlm_lock *lock,
+			     struct dlm_lock_resource *res)
+{
+	dlm_lockres_get(res);
+	lock->lockres = res;
+}
+
+/* drop ref on lockres, if there is still one associated with lock */
+static void dlm_lock_detach_lockres(struct dlm_lock *lock)
+{
+	struct dlm_lock_resource *res;
+
+	res = lock->lockres;
+	if (res) {
+		lock->lockres = NULL;
+		mlog(0, "removing lock's lockres reference\n");
+		dlm_lockres_put(res);
+	}
+}
+
+static void dlm_init_lock(struct dlm_lock *newlock, int type,
+			  u8 node, u64 cookie)
+{
+	INIT_LIST_HEAD(&newlock->list);
+	INIT_LIST_HEAD(&newlock->ast_list);
+	INIT_LIST_HEAD(&newlock->bast_list);
+	spin_lock_init(&newlock->spinlock);
+	newlock->ml.type = type;
+	newlock->ml.convert_type = LKM_IVMODE;
+	newlock->ml.highest_blocked = LKM_IVMODE;
+	newlock->ml.node = node;
+	newlock->ml.pad1 = 0;
+	newlock->ml.list = 0;
+	newlock->ml.flags = 0;
+	newlock->ast = NULL;
+	newlock->bast = NULL;
+	newlock->astdata = NULL;
+	newlock->ml.cookie = cpu_to_be64(cookie);
+	newlock->ast_pending = 0;
+	newlock->bast_pending = 0;
+	newlock->convert_pending = 0;
+	newlock->lock_pending = 0;
+	newlock->unlock_pending = 0;
+	newlock->cancel_pending = 0;
+	newlock->lksb_kernel_allocated = 0;
+
+	kref_init(&newlock->lock_refs);
+}
+
+struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
+			       struct dlm_lockstatus *lksb)
+{
+	struct dlm_lock *lock;
+	int kernel_allocated = 0;
+
+	lock = kmem_cache_zalloc(dlm_lock_cache, GFP_NOFS);
+	if (!lock)
+		return NULL;
+
+	if (!lksb) {
+		/* zero memory only if kernel-allocated */
+		lksb = kzalloc(sizeof(*lksb), GFP_NOFS);
+		if (!lksb) {
+			kmem_cache_free(dlm_lock_cache, lock);
+			return NULL;
+		}
+		kernel_allocated = 1;
+	}
+
+	dlm_init_lock(lock, type, node, cookie);
+	if (kernel_allocated)
+		lock->lksb_kernel_allocated = 1;
+	lock->lksb = lksb;
+	lksb->lockid = lock;
+	return lock;
+}
+
+/* handler for lock creation net message
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
+ */
+int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_lock *newlock = NULL;
+	struct dlm_lockstatus *lksb = NULL;
+	enum dlm_status status = DLM_NORMAL;
+	char *name;
+	unsigned int namelen;
+
+	BUG_ON(!dlm);
+
+	if (!dlm_grab(dlm))
+		return DLM_REJECTED;
+
+	name = create->name;
+	namelen = create->namelen;
+	status = DLM_REJECTED;
+	if (!dlm_domain_fully_joined(dlm)) {
+		mlog(ML_ERROR, "Domain %s not fully joined, but node %u is "
+		     "sending a create_lock message for lock %.*s!\n",
+		     dlm->name, create->node_idx, namelen, name);
+		dlm_error(status);
+		goto leave;
+	}
+
+	status = DLM_IVBUFLEN;
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		dlm_error(status);
+		goto leave;
+	}
+
+	status = DLM_SYSERR;
+	newlock = dlm_new_lock(create->requested_type,
+			       create->node_idx,
+			       be64_to_cpu(create->cookie), NULL);
+	if (!newlock) {
+		dlm_error(status);
+		goto leave;
+	}
+
+	lksb = newlock->lksb;
+
+	if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
+		lksb->flags |= DLM_LKSB_GET_LVB;
+		mlog(0, "set DLM_LKSB_GET_LVB flag\n");
+	}
+
+	status = DLM_IVLOCKID;
+	res = dlm_lookup_lockres(dlm, name, namelen);
+	if (!res) {
+		dlm_error(status);
+		goto leave;
+	}
+
+	spin_lock(&res->spinlock);
+	status = __dlm_lockres_state_to_status(res);
+	spin_unlock(&res->spinlock);
+
+	if (status != DLM_NORMAL) {
+		mlog(0, "lockres recovering/migrating/in-progress\n");
+		goto leave;
+	}
+
+	dlm_lock_attach_lockres(newlock, res);
+
+	status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
+leave:
+	if (status != DLM_NORMAL)
+		if (newlock)
+			dlm_lock_put(newlock);
+
+	if (res)
+		dlm_lockres_put(res);
+
+	dlm_put(dlm);
+
+	return status;
+}
+
+
+/* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
+static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
+{
+	u64 tmpnode = node_num;
+
+	/* shift single byte of node num into top 8 bits */
+	tmpnode <<= 56;
+
+	spin_lock(&dlm_cookie_lock);
+	*cookie = (dlm_next_cookie | tmpnode);
+	if (++dlm_next_cookie & 0xff00000000000000ull) {
+		mlog(0, "This node's cookie will now wrap!\n");
+		dlm_next_cookie = 1;
+	}
+	spin_unlock(&dlm_cookie_lock);
+}
+
+enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
+			struct dlm_lockstatus *lksb, int flags,
+			const char *name, int namelen, dlm_astlockfunc_t *ast,
+			void *data, dlm_bastlockfunc_t *bast)
+{
+	enum dlm_status status;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_lock *lock = NULL;
+	int convert = 0, recovery = 0;
+
+	/* yes this function is a mess.
+	 * TODO: clean this up.  lots of common code in the
+	 *       lock and convert paths, especially in the retry blocks */
+	if (!lksb) {
+		dlm_error(DLM_BADARGS);
+		return DLM_BADARGS;
+	}
+
+	status = DLM_BADPARAM;
+	if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
+		dlm_error(status);
+		goto error;
+	}
+
+	if (flags & ~LKM_VALID_FLAGS) {
+		dlm_error(status);
+		goto error;
+	}
+
+	convert = (flags & LKM_CONVERT);
+	recovery = (flags & LKM_RECOVERY);
+
+	if (recovery &&
+	    (!dlm_is_recovery_lock(name, namelen) || convert) ) {
+		dlm_error(status);
+		goto error;
+	}
+	if (convert && (flags & LKM_LOCAL)) {
+		mlog(ML_ERROR, "strange LOCAL convert request!\n");
+		goto error;
+	}
+
+	if (convert) {
+		/* CONVERT request */
+
+		/* if converting, must pass in a valid dlm_lock */
+		lock = lksb->lockid;
+		if (!lock) {
+			mlog(ML_ERROR, "NULL lock pointer in convert "
+			     "request\n");
+			goto error;
+		}
+
+		res = lock->lockres;
+		if (!res) {
+			mlog(ML_ERROR, "NULL lockres pointer in convert "
+			     "request\n");
+			goto error;
+		}
+		dlm_lockres_get(res);
+
+		/* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
+	 	 * static after the original lock call.  convert requests will
+		 * ensure that everything is the same, or return DLM_BADARGS.
+	 	 * this means that DLM_DENIED_NOASTS will never be returned.
+	 	 */
+		if (lock->lksb != lksb || lock->ast != ast ||
+		    lock->bast != bast || lock->astdata != data) {
+			status = DLM_BADARGS;
+			mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
+			     "astdata=%p\n", lksb, ast, bast, data);
+			mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
+			     "astdata=%p\n", lock->lksb, lock->ast,
+			     lock->bast, lock->astdata);
+			goto error;
+		}
+retry_convert:
+		dlm_wait_for_recovery(dlm);
+
+		if (res->owner == dlm->node_num)
+			status = dlmconvert_master(dlm, res, lock, flags, mode);
+		else
+			status = dlmconvert_remote(dlm, res, lock, flags, mode);
+		if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
+		    status == DLM_FORWARD) {
+			/* for now, see how this works without sleeping
+			 * and just retry right away.  I suspect the reco
+			 * or migration will complete fast enough that
+			 * no waiting will be necessary */
+			mlog(0, "retrying convert with migration/recovery/"
+			     "in-progress\n");
+			msleep(100);
+			goto retry_convert;
+		}
+	} else {
+		u64 tmpcookie;
+
+		/* LOCK request */
+		status = DLM_BADARGS;
+		if (!name) {
+			dlm_error(status);
+			goto error;
+		}
+
+		status = DLM_IVBUFLEN;
+		if (namelen > DLM_LOCKID_NAME_MAX || namelen < 1) {
+			dlm_error(status);
+			goto error;
+		}
+
+		dlm_get_next_cookie(dlm->node_num, &tmpcookie);
+		lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
+		if (!lock) {
+			dlm_error(status);
+			goto error;
+		}
+
+		if (!recovery)
+			dlm_wait_for_recovery(dlm);
+
+		/* find or create the lock resource */
+		res = dlm_get_lock_resource(dlm, name, namelen, flags);
+		if (!res) {
+			status = DLM_IVLOCKID;
+			dlm_error(status);
+			goto error;
+		}
+
+		mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
+		mlog(0, "creating lock: lock=%p res=%p\n", lock, res);
+
+		dlm_lock_attach_lockres(lock, res);
+		lock->ast = ast;
+		lock->bast = bast;
+		lock->astdata = data;
+
+retry_lock:
+		if (flags & LKM_VALBLK) {
+			mlog(0, "LKM_VALBLK passed by caller\n");
+
+			/* LVB requests for non PR, PW or EX locks are
+			 * ignored. */
+			if (mode < LKM_PRMODE)
+				flags &= ~LKM_VALBLK;
+			else {
+				flags |= LKM_GET_LVB;
+				lock->lksb->flags |= DLM_LKSB_GET_LVB;
+			}
+		}
+
+		if (res->owner == dlm->node_num)
+			status = dlmlock_master(dlm, res, lock, flags);
+		else
+			status = dlmlock_remote(dlm, res, lock, flags);
+
+		if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
+		    status == DLM_FORWARD) {
+			msleep(100);
+			if (recovery) {
+				if (status != DLM_RECOVERING)
+					goto retry_lock;
+				/* wait to see the node go down, then
+				 * drop down and allow the lockres to
+				 * get cleaned up.  need to remaster. */
+				dlm_wait_for_node_death(dlm, res->owner,
+						DLM_NODE_DEATH_WAIT_MAX);
+			} else {
+				dlm_wait_for_recovery(dlm);
+				goto retry_lock;
+			}
+		}
+
+		/* Inflight taken in dlm_get_lock_resource() is dropped here */
+		spin_lock(&res->spinlock);
+		dlm_lockres_drop_inflight_ref(dlm, res);
+		spin_unlock(&res->spinlock);
+
+		dlm_lockres_calc_usage(dlm, res);
+		dlm_kick_thread(dlm, res);
+
+		if (status != DLM_NORMAL) {
+			lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
+			if (status != DLM_NOTQUEUED)
+				dlm_error(status);
+			goto error;
+		}
+	}
+
+error:
+	if (status != DLM_NORMAL) {
+		if (lock && !convert)
+			dlm_lock_put(lock);
+		// this is kind of unnecessary
+		lksb->status = status;
+	}
+
+	/* put lockres ref from the convert path
+	 * or from dlm_get_lock_resource */
+	if (res)
+		dlm_lockres_put(res);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(dlmlock);
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
new file mode 100644
index 000000000..227da5b1b
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -0,0 +1,3564 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmmod.c
+ *
+ * standalone DLM module
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+#include "dlmdebug.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
+#include "../cluster/masklog.h"
+
+static void dlm_mle_node_down(struct dlm_ctxt *dlm,
+			      struct dlm_master_list_entry *mle,
+			      struct o2nm_node *node,
+			      int idx);
+static void dlm_mle_node_up(struct dlm_ctxt *dlm,
+			    struct dlm_master_list_entry *mle,
+			    struct o2nm_node *node,
+			    int idx);
+
+static void dlm_assert_master_worker(struct dlm_work_item *item, void *data);
+static int dlm_do_assert_master(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res,
+				void *nodemap, u32 flags);
+static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data);
+
+static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
+				struct dlm_master_list_entry *mle,
+				const char *name,
+				unsigned int namelen)
+{
+	if (dlm != mle->dlm)
+		return 0;
+
+	if (namelen != mle->mnamelen ||
+	    memcmp(name, mle->mname, namelen) != 0)
+		return 0;
+
+	return 1;
+}
+
+static struct kmem_cache *dlm_lockres_cache;
+static struct kmem_cache *dlm_lockname_cache;
+static struct kmem_cache *dlm_mle_cache;
+
+static void dlm_mle_release(struct kref *kref);
+static void dlm_init_mle(struct dlm_master_list_entry *mle,
+			enum dlm_mle_type type,
+			struct dlm_ctxt *dlm,
+			struct dlm_lock_resource *res,
+			const char *name,
+			unsigned int namelen);
+static void dlm_put_mle(struct dlm_master_list_entry *mle);
+static void __dlm_put_mle(struct dlm_master_list_entry *mle);
+static int dlm_find_mle(struct dlm_ctxt *dlm,
+			struct dlm_master_list_entry **mle,
+			char *name, unsigned int namelen);
+
+static int dlm_do_master_request(struct dlm_lock_resource *res,
+				 struct dlm_master_list_entry *mle, int to);
+
+
+static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     struct dlm_master_list_entry *mle,
+				     int *blocked);
+static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
+				    struct dlm_lock_resource *res,
+				    struct dlm_master_list_entry *mle,
+				    int blocked);
+static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
+				 struct dlm_lock_resource *res,
+				 struct dlm_master_list_entry *mle,
+				 struct dlm_master_list_entry **oldmle,
+				 const char *name, unsigned int namelen,
+				 u8 new_master, u8 master);
+
+static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
+				    struct dlm_lock_resource *res);
+static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res);
+static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res,
+				       u8 target);
+static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res);
+
+
+int dlm_is_host_down(int errno)
+{
+	switch (errno) {
+		case -EBADF:
+		case -ECONNREFUSED:
+		case -ENOTCONN:
+		case -ECONNRESET:
+		case -EPIPE:
+		case -EHOSTDOWN:
+		case -EHOSTUNREACH:
+		case -ETIMEDOUT:
+		case -ECONNABORTED:
+		case -ENETDOWN:
+		case -ENETUNREACH:
+		case -ENETRESET:
+		case -ESHUTDOWN:
+		case -ENOPROTOOPT:
+		case -EINVAL:   /* if returned from our tcp code,
+				   this means there is no socket */
+			return 1;
+	}
+	return 0;
+}
+
+
+/*
+ * MASTER LIST FUNCTIONS
+ */
+
+
+/*
+ * regarding master list entries and heartbeat callbacks:
+ *
+ * in order to avoid sleeping and allocation that occurs in
+ * heartbeat, master list entries are simply attached to the
+ * dlm's established heartbeat callbacks.  the mle is attached
+ * when it is created, and since the dlm->spinlock is held at
+ * that time, any heartbeat event will be properly discovered
+ * by the mle.  the mle needs to be detached from the
+ * dlm->mle_hb_events list as soon as heartbeat events are no
+ * longer useful to the mle, and before the mle is freed.
+ *
+ * as a general rule, heartbeat events are no longer needed by
+ * the mle once an "answer" regarding the lock master has been
+ * received.
+ */
+static inline void __dlm_mle_attach_hb_events(struct dlm_ctxt *dlm,
+					      struct dlm_master_list_entry *mle)
+{
+	assert_spin_locked(&dlm->spinlock);
+
+	list_add_tail(&mle->hb_events, &dlm->mle_hb_events);
+}
+
+
+static inline void __dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
+					      struct dlm_master_list_entry *mle)
+{
+	if (!list_empty(&mle->hb_events))
+		list_del_init(&mle->hb_events);
+}
+
+
+static inline void dlm_mle_detach_hb_events(struct dlm_ctxt *dlm,
+					    struct dlm_master_list_entry *mle)
+{
+	spin_lock(&dlm->spinlock);
+	__dlm_mle_detach_hb_events(dlm, mle);
+	spin_unlock(&dlm->spinlock);
+}
+
+static void dlm_get_mle_inuse(struct dlm_master_list_entry *mle)
+{
+	struct dlm_ctxt *dlm;
+	dlm = mle->dlm;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&dlm->master_lock);
+	mle->inuse++;
+	kref_get(&mle->mle_refs);
+}
+
+static void dlm_put_mle_inuse(struct dlm_master_list_entry *mle)
+{
+	struct dlm_ctxt *dlm;
+	dlm = mle->dlm;
+
+	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->master_lock);
+	mle->inuse--;
+	__dlm_put_mle(mle);
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+
+}
+
+/* remove from list and free */
+static void __dlm_put_mle(struct dlm_master_list_entry *mle)
+{
+	struct dlm_ctxt *dlm;
+	dlm = mle->dlm;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&dlm->master_lock);
+	if (!kref_read(&mle->mle_refs)) {
+		/* this may or may not crash, but who cares.
+		 * it's a BUG. */
+		mlog(ML_ERROR, "bad mle: %p\n", mle);
+		dlm_print_one_mle(mle);
+		BUG();
+	} else
+		kref_put(&mle->mle_refs, dlm_mle_release);
+}
+
+
+/* must not have any spinlocks coming in */
+static void dlm_put_mle(struct dlm_master_list_entry *mle)
+{
+	struct dlm_ctxt *dlm;
+	dlm = mle->dlm;
+
+	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->master_lock);
+	__dlm_put_mle(mle);
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+}
+
+static inline void dlm_get_mle(struct dlm_master_list_entry *mle)
+{
+	kref_get(&mle->mle_refs);
+}
+
+static void dlm_init_mle(struct dlm_master_list_entry *mle,
+			enum dlm_mle_type type,
+			struct dlm_ctxt *dlm,
+			struct dlm_lock_resource *res,
+			const char *name,
+			unsigned int namelen)
+{
+	assert_spin_locked(&dlm->spinlock);
+
+	mle->dlm = dlm;
+	mle->type = type;
+	INIT_HLIST_NODE(&mle->master_hash_node);
+	INIT_LIST_HEAD(&mle->hb_events);
+	memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
+	spin_lock_init(&mle->spinlock);
+	init_waitqueue_head(&mle->wq);
+	atomic_set(&mle->woken, 0);
+	kref_init(&mle->mle_refs);
+	memset(mle->response_map, 0, sizeof(mle->response_map));
+	mle->master = O2NM_MAX_NODES;
+	mle->new_master = O2NM_MAX_NODES;
+	mle->inuse = 0;
+
+	BUG_ON(mle->type != DLM_MLE_BLOCK &&
+	       mle->type != DLM_MLE_MASTER &&
+	       mle->type != DLM_MLE_MIGRATION);
+
+	if (mle->type == DLM_MLE_MASTER) {
+		BUG_ON(!res);
+		mle->mleres = res;
+		memcpy(mle->mname, res->lockname.name, res->lockname.len);
+		mle->mnamelen = res->lockname.len;
+		mle->mnamehash = res->lockname.hash;
+	} else {
+		BUG_ON(!name);
+		mle->mleres = NULL;
+		memcpy(mle->mname, name, namelen);
+		mle->mnamelen = namelen;
+		mle->mnamehash = dlm_lockid_hash(name, namelen);
+	}
+
+	atomic_inc(&dlm->mle_tot_count[mle->type]);
+	atomic_inc(&dlm->mle_cur_count[mle->type]);
+
+	/* copy off the node_map and register hb callbacks on our copy */
+	memcpy(mle->node_map, dlm->domain_map, sizeof(mle->node_map));
+	memcpy(mle->vote_map, dlm->domain_map, sizeof(mle->vote_map));
+	clear_bit(dlm->node_num, mle->vote_map);
+	clear_bit(dlm->node_num, mle->node_map);
+
+	/* attach the mle to the domain node up/down events */
+	__dlm_mle_attach_hb_events(dlm, mle);
+}
+
+void __dlm_unlink_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
+{
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&dlm->master_lock);
+
+	if (!hlist_unhashed(&mle->master_hash_node))
+		hlist_del_init(&mle->master_hash_node);
+}
+
+void __dlm_insert_mle(struct dlm_ctxt *dlm, struct dlm_master_list_entry *mle)
+{
+	struct hlist_head *bucket;
+
+	assert_spin_locked(&dlm->master_lock);
+
+	bucket = dlm_master_hash(dlm, mle->mnamehash);
+	hlist_add_head(&mle->master_hash_node, bucket);
+}
+
+/* returns 1 if found, 0 if not */
+static int dlm_find_mle(struct dlm_ctxt *dlm,
+			struct dlm_master_list_entry **mle,
+			char *name, unsigned int namelen)
+{
+	struct dlm_master_list_entry *tmpmle;
+	struct hlist_head *bucket;
+	unsigned int hash;
+
+	assert_spin_locked(&dlm->master_lock);
+
+	hash = dlm_lockid_hash(name, namelen);
+	bucket = dlm_master_hash(dlm, hash);
+	hlist_for_each_entry(tmpmle, bucket, master_hash_node) {
+		if (!dlm_mle_equal(dlm, tmpmle, name, namelen))
+			continue;
+		dlm_get_mle(tmpmle);
+		*mle = tmpmle;
+		return 1;
+	}
+	return 0;
+}
+
+void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up)
+{
+	struct dlm_master_list_entry *mle;
+
+	assert_spin_locked(&dlm->spinlock);
+
+	list_for_each_entry(mle, &dlm->mle_hb_events, hb_events) {
+		if (node_up)
+			dlm_mle_node_up(dlm, mle, NULL, idx);
+		else
+			dlm_mle_node_down(dlm, mle, NULL, idx);
+	}
+}
+
+static void dlm_mle_node_down(struct dlm_ctxt *dlm,
+			      struct dlm_master_list_entry *mle,
+			      struct o2nm_node *node, int idx)
+{
+	spin_lock(&mle->spinlock);
+
+	if (!test_bit(idx, mle->node_map))
+		mlog(0, "node %u already removed from nodemap!\n", idx);
+	else
+		clear_bit(idx, mle->node_map);
+
+	spin_unlock(&mle->spinlock);
+}
+
+static void dlm_mle_node_up(struct dlm_ctxt *dlm,
+			    struct dlm_master_list_entry *mle,
+			    struct o2nm_node *node, int idx)
+{
+	spin_lock(&mle->spinlock);
+
+	if (test_bit(idx, mle->node_map))
+		mlog(0, "node %u already in node map!\n", idx);
+	else
+		set_bit(idx, mle->node_map);
+
+	spin_unlock(&mle->spinlock);
+}
+
+
+int dlm_init_mle_cache(void)
+{
+	dlm_mle_cache = kmem_cache_create("o2dlm_mle",
+					  sizeof(struct dlm_master_list_entry),
+					  0, SLAB_HWCACHE_ALIGN,
+					  NULL);
+	if (dlm_mle_cache == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void dlm_destroy_mle_cache(void)
+{
+	kmem_cache_destroy(dlm_mle_cache);
+}
+
+static void dlm_mle_release(struct kref *kref)
+{
+	struct dlm_master_list_entry *mle;
+	struct dlm_ctxt *dlm;
+
+	mle = container_of(kref, struct dlm_master_list_entry, mle_refs);
+	dlm = mle->dlm;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&dlm->master_lock);
+
+	mlog(0, "Releasing mle for %.*s, type %d\n", mle->mnamelen, mle->mname,
+	     mle->type);
+
+	/* remove from list if not already */
+	__dlm_unlink_mle(dlm, mle);
+
+	/* detach the mle from the domain node up/down events */
+	__dlm_mle_detach_hb_events(dlm, mle);
+
+	atomic_dec(&dlm->mle_cur_count[mle->type]);
+
+	/* NOTE: kfree under spinlock here.
+	 * if this is bad, we can move this to a freelist. */
+	kmem_cache_free(dlm_mle_cache, mle);
+}
+
+
+/*
+ * LOCK RESOURCE FUNCTIONS
+ */
+
+int dlm_init_master_caches(void)
+{
+	dlm_lockres_cache = kmem_cache_create("o2dlm_lockres",
+					      sizeof(struct dlm_lock_resource),
+					      0, SLAB_HWCACHE_ALIGN, NULL);
+	if (!dlm_lockres_cache)
+		goto bail;
+
+	dlm_lockname_cache = kmem_cache_create("o2dlm_lockname",
+					       DLM_LOCKID_NAME_MAX, 0,
+					       SLAB_HWCACHE_ALIGN, NULL);
+	if (!dlm_lockname_cache)
+		goto bail;
+
+	return 0;
+bail:
+	dlm_destroy_master_caches();
+	return -ENOMEM;
+}
+
+void dlm_destroy_master_caches(void)
+{
+	kmem_cache_destroy(dlm_lockname_cache);
+	dlm_lockname_cache = NULL;
+
+	kmem_cache_destroy(dlm_lockres_cache);
+	dlm_lockres_cache = NULL;
+}
+
+static void dlm_lockres_release(struct kref *kref)
+{
+	struct dlm_lock_resource *res;
+	struct dlm_ctxt *dlm;
+
+	res = container_of(kref, struct dlm_lock_resource, refs);
+	dlm = res->dlm;
+
+	/* This should not happen -- all lockres' have a name
+	 * associated with them at init time. */
+	BUG_ON(!res->lockname.name);
+
+	mlog(0, "destroying lockres %.*s\n", res->lockname.len,
+	     res->lockname.name);
+
+	atomic_dec(&dlm->res_cur_count);
+
+	if (!hlist_unhashed(&res->hash_node) ||
+	    !list_empty(&res->granted) ||
+	    !list_empty(&res->converting) ||
+	    !list_empty(&res->blocked) ||
+	    !list_empty(&res->dirty) ||
+	    !list_empty(&res->recovering) ||
+	    !list_empty(&res->purge)) {
+		mlog(ML_ERROR,
+		     "Going to BUG for resource %.*s."
+		     "  We're on a list! [%c%c%c%c%c%c%c]\n",
+		     res->lockname.len, res->lockname.name,
+		     !hlist_unhashed(&res->hash_node) ? 'H' : ' ',
+		     !list_empty(&res->granted) ? 'G' : ' ',
+		     !list_empty(&res->converting) ? 'C' : ' ',
+		     !list_empty(&res->blocked) ? 'B' : ' ',
+		     !list_empty(&res->dirty) ? 'D' : ' ',
+		     !list_empty(&res->recovering) ? 'R' : ' ',
+		     !list_empty(&res->purge) ? 'P' : ' ');
+
+		dlm_print_one_lock_resource(res);
+	}
+
+	/* By the time we're ready to blow this guy away, we shouldn't
+	 * be on any lists. */
+	BUG_ON(!hlist_unhashed(&res->hash_node));
+	BUG_ON(!list_empty(&res->granted));
+	BUG_ON(!list_empty(&res->converting));
+	BUG_ON(!list_empty(&res->blocked));
+	BUG_ON(!list_empty(&res->dirty));
+	BUG_ON(!list_empty(&res->recovering));
+	BUG_ON(!list_empty(&res->purge));
+
+	kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
+
+	kmem_cache_free(dlm_lockres_cache, res);
+}
+
+void dlm_lockres_put(struct dlm_lock_resource *res)
+{
+	kref_put(&res->refs, dlm_lockres_release);
+}
+
+static void dlm_init_lockres(struct dlm_ctxt *dlm,
+			     struct dlm_lock_resource *res,
+			     const char *name, unsigned int namelen)
+{
+	char *qname;
+
+	/* If we memset here, we lose our reference to the kmalloc'd
+	 * res->lockname.name, so be sure to init every field
+	 * correctly! */
+
+	qname = (char *) res->lockname.name;
+	memcpy(qname, name, namelen);
+
+	res->lockname.len = namelen;
+	res->lockname.hash = dlm_lockid_hash(name, namelen);
+
+	init_waitqueue_head(&res->wq);
+	spin_lock_init(&res->spinlock);
+	INIT_HLIST_NODE(&res->hash_node);
+	INIT_LIST_HEAD(&res->granted);
+	INIT_LIST_HEAD(&res->converting);
+	INIT_LIST_HEAD(&res->blocked);
+	INIT_LIST_HEAD(&res->dirty);
+	INIT_LIST_HEAD(&res->recovering);
+	INIT_LIST_HEAD(&res->purge);
+	INIT_LIST_HEAD(&res->tracking);
+	atomic_set(&res->asts_reserved, 0);
+	res->migration_pending = 0;
+	res->inflight_locks = 0;
+	res->inflight_assert_workers = 0;
+
+	res->dlm = dlm;
+
+	kref_init(&res->refs);
+
+	atomic_inc(&dlm->res_tot_count);
+	atomic_inc(&dlm->res_cur_count);
+
+	/* just for consistency */
+	spin_lock(&res->spinlock);
+	dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
+	spin_unlock(&res->spinlock);
+
+	res->state = DLM_LOCK_RES_IN_PROGRESS;
+
+	res->last_used = 0;
+
+	spin_lock(&dlm->track_lock);
+	list_add_tail(&res->tracking, &dlm->tracking_list);
+	spin_unlock(&dlm->track_lock);
+
+	memset(res->lvb, 0, DLM_LVB_LEN);
+	memset(res->refmap, 0, sizeof(res->refmap));
+}
+
+struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
+				   const char *name,
+				   unsigned int namelen)
+{
+	struct dlm_lock_resource *res = NULL;
+
+	res = kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
+	if (!res)
+		goto error;
+
+	res->lockname.name = kmem_cache_zalloc(dlm_lockname_cache, GFP_NOFS);
+	if (!res->lockname.name)
+		goto error;
+
+	dlm_init_lockres(dlm, res, name, namelen);
+	return res;
+
+error:
+	if (res)
+		kmem_cache_free(dlm_lockres_cache, res);
+	return NULL;
+}
+
+void dlm_lockres_set_refmap_bit(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res, int bit)
+{
+	assert_spin_locked(&res->spinlock);
+
+	mlog(0, "res %.*s, set node %u, %ps()\n", res->lockname.len,
+	     res->lockname.name, bit, __builtin_return_address(0));
+
+	set_bit(bit, res->refmap);
+}
+
+void dlm_lockres_clear_refmap_bit(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res, int bit)
+{
+	assert_spin_locked(&res->spinlock);
+
+	mlog(0, "res %.*s, clr node %u, %ps()\n", res->lockname.len,
+	     res->lockname.name, bit, __builtin_return_address(0));
+
+	clear_bit(bit, res->refmap);
+}
+
+static void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
+				   struct dlm_lock_resource *res)
+{
+	res->inflight_locks++;
+
+	mlog(0, "%s: res %.*s, inflight++: now %u, %ps()\n", dlm->name,
+	     res->lockname.len, res->lockname.name, res->inflight_locks,
+	     __builtin_return_address(0));
+}
+
+void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
+				   struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&res->spinlock);
+	__dlm_lockres_grab_inflight_ref(dlm, res);
+}
+
+void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
+				   struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&res->spinlock);
+
+	BUG_ON(res->inflight_locks == 0);
+
+	res->inflight_locks--;
+
+	mlog(0, "%s: res %.*s, inflight--: now %u, %ps()\n", dlm->name,
+	     res->lockname.len, res->lockname.name, res->inflight_locks,
+	     __builtin_return_address(0));
+
+	wake_up(&res->wq);
+}
+
+void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&res->spinlock);
+	res->inflight_assert_workers++;
+	mlog(0, "%s:%.*s: inflight assert worker++: now %u\n",
+			dlm->name, res->lockname.len, res->lockname.name,
+			res->inflight_assert_workers);
+}
+
+static void __dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&res->spinlock);
+	BUG_ON(res->inflight_assert_workers == 0);
+	res->inflight_assert_workers--;
+	mlog(0, "%s:%.*s: inflight assert worker--: now %u\n",
+			dlm->name, res->lockname.len, res->lockname.name,
+			res->inflight_assert_workers);
+}
+
+static void dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res)
+{
+	spin_lock(&res->spinlock);
+	__dlm_lockres_drop_inflight_worker(dlm, res);
+	spin_unlock(&res->spinlock);
+}
+
+/*
+ * lookup a lock resource by name.
+ * may already exist in the hashtable.
+ * lockid is null terminated
+ *
+ * if not, allocate enough for the lockres and for
+ * the temporary structure used in doing the mastering.
+ *
+ * also, do a lookup in the dlm->master_list to see
+ * if another node has begun mastering the same lock.
+ * if so, there should be a block entry in there
+ * for this name, and we should *not* attempt to master
+ * the lock here.   need to wait around for that node
+ * to assert_master (or die).
+ *
+ */
+struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm,
+					  const char *lockid,
+					  int namelen,
+					  int flags)
+{
+	struct dlm_lock_resource *tmpres=NULL, *res=NULL;
+	struct dlm_master_list_entry *mle = NULL;
+	struct dlm_master_list_entry *alloc_mle = NULL;
+	int blocked = 0;
+	int ret, nodenum;
+	struct dlm_node_iter iter;
+	unsigned int hash;
+	int tries = 0;
+	int bit, wait_on_recovery = 0;
+
+	BUG_ON(!lockid);
+
+	hash = dlm_lockid_hash(lockid, namelen);
+
+	mlog(0, "get lockres %s (len %d)\n", lockid, namelen);
+
+lookup:
+	spin_lock(&dlm->spinlock);
+	tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash);
+	if (tmpres) {
+		spin_unlock(&dlm->spinlock);
+		spin_lock(&tmpres->spinlock);
+
+		/*
+		 * Right after dlm spinlock was released, dlm_thread could have
+		 * purged the lockres. Check if lockres got unhashed. If so
+		 * start over.
+		 */
+		if (hlist_unhashed(&tmpres->hash_node)) {
+			spin_unlock(&tmpres->spinlock);
+			dlm_lockres_put(tmpres);
+			tmpres = NULL;
+			goto lookup;
+		}
+
+		/* Wait on the thread that is mastering the resource */
+		if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
+			__dlm_wait_on_lockres(tmpres);
+			BUG_ON(tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN);
+			spin_unlock(&tmpres->spinlock);
+			dlm_lockres_put(tmpres);
+			tmpres = NULL;
+			goto lookup;
+		}
+
+		/* Wait on the resource purge to complete before continuing */
+		if (tmpres->state & DLM_LOCK_RES_DROPPING_REF) {
+			BUG_ON(tmpres->owner == dlm->node_num);
+			__dlm_wait_on_lockres_flags(tmpres,
+						    DLM_LOCK_RES_DROPPING_REF);
+			spin_unlock(&tmpres->spinlock);
+			dlm_lockres_put(tmpres);
+			tmpres = NULL;
+			goto lookup;
+		}
+
+		/* Grab inflight ref to pin the resource */
+		dlm_lockres_grab_inflight_ref(dlm, tmpres);
+
+		spin_unlock(&tmpres->spinlock);
+		if (res) {
+			spin_lock(&dlm->track_lock);
+			if (!list_empty(&res->tracking))
+				list_del_init(&res->tracking);
+			else
+				mlog(ML_ERROR, "Resource %.*s not "
+						"on the Tracking list\n",
+						res->lockname.len,
+						res->lockname.name);
+			spin_unlock(&dlm->track_lock);
+			dlm_lockres_put(res);
+		}
+		res = tmpres;
+		goto leave;
+	}
+
+	if (!res) {
+		spin_unlock(&dlm->spinlock);
+		mlog(0, "allocating a new resource\n");
+		/* nothing found and we need to allocate one. */
+		alloc_mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
+		if (!alloc_mle)
+			goto leave;
+		res = dlm_new_lockres(dlm, lockid, namelen);
+		if (!res)
+			goto leave;
+		goto lookup;
+	}
+
+	mlog(0, "no lockres found, allocated our own: %p\n", res);
+
+	if (flags & LKM_LOCAL) {
+		/* caller knows it's safe to assume it's not mastered elsewhere
+		 * DONE!  return right away */
+		spin_lock(&res->spinlock);
+		dlm_change_lockres_owner(dlm, res, dlm->node_num);
+		__dlm_insert_lockres(dlm, res);
+		dlm_lockres_grab_inflight_ref(dlm, res);
+		spin_unlock(&res->spinlock);
+		spin_unlock(&dlm->spinlock);
+		/* lockres still marked IN_PROGRESS */
+		goto wake_waiters;
+	}
+
+	/* check master list to see if another node has started mastering it */
+	spin_lock(&dlm->master_lock);
+
+	/* if we found a block, wait for lock to be mastered by another node */
+	blocked = dlm_find_mle(dlm, &mle, (char *)lockid, namelen);
+	if (blocked) {
+		int mig;
+		if (mle->type == DLM_MLE_MASTER) {
+			mlog(ML_ERROR, "master entry for nonexistent lock!\n");
+			BUG();
+		}
+		mig = (mle->type == DLM_MLE_MIGRATION);
+		/* if there is a migration in progress, let the migration
+		 * finish before continuing.  we can wait for the absence
+		 * of the MIGRATION mle: either the migrate finished or
+		 * one of the nodes died and the mle was cleaned up.
+		 * if there is a BLOCK here, but it already has a master
+		 * set, we are too late.  the master does not have a ref
+		 * for us in the refmap.  detach the mle and drop it.
+		 * either way, go back to the top and start over. */
+		if (mig || mle->master != O2NM_MAX_NODES) {
+			BUG_ON(mig && mle->master == dlm->node_num);
+			/* we arrived too late.  the master does not
+			 * have a ref for us. retry. */
+			mlog(0, "%s:%.*s: late on %s\n",
+			     dlm->name, namelen, lockid,
+			     mig ?  "MIGRATION" : "BLOCK");
+			spin_unlock(&dlm->master_lock);
+			spin_unlock(&dlm->spinlock);
+
+			/* master is known, detach */
+			if (!mig)
+				dlm_mle_detach_hb_events(dlm, mle);
+			dlm_put_mle(mle);
+			mle = NULL;
+			/* this is lame, but we can't wait on either
+			 * the mle or lockres waitqueue here */
+			if (mig)
+				msleep(100);
+			goto lookup;
+		}
+	} else {
+		/* go ahead and try to master lock on this node */
+		mle = alloc_mle;
+		/* make sure this does not get freed below */
+		alloc_mle = NULL;
+		dlm_init_mle(mle, DLM_MLE_MASTER, dlm, res, NULL, 0);
+		set_bit(dlm->node_num, mle->maybe_map);
+		__dlm_insert_mle(dlm, mle);
+
+		/* still holding the dlm spinlock, check the recovery map
+		 * to see if there are any nodes that still need to be
+		 * considered.  these will not appear in the mle nodemap
+		 * but they might own this lockres.  wait on them. */
+		bit = find_first_bit(dlm->recovery_map, O2NM_MAX_NODES);
+		if (bit < O2NM_MAX_NODES) {
+			mlog(0, "%s: res %.*s, At least one node (%d) "
+			     "to recover before lock mastery can begin\n",
+			     dlm->name, namelen, (char *)lockid, bit);
+			wait_on_recovery = 1;
+		}
+	}
+
+	/* at this point there is either a DLM_MLE_BLOCK or a
+	 * DLM_MLE_MASTER on the master list, so it's safe to add the
+	 * lockres to the hashtable.  anyone who finds the lock will
+	 * still have to wait on the IN_PROGRESS. */
+
+	/* finally add the lockres to its hash bucket */
+	__dlm_insert_lockres(dlm, res);
+
+	/* since this lockres is new it doesn't not require the spinlock */
+	__dlm_lockres_grab_inflight_ref(dlm, res);
+
+	/* get an extra ref on the mle in case this is a BLOCK
+	 * if so, the creator of the BLOCK may try to put the last
+	 * ref at this time in the assert master handler, so we
+	 * need an extra one to keep from a bad ptr deref. */
+	dlm_get_mle_inuse(mle);
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+
+redo_request:
+	while (wait_on_recovery) {
+		/* any cluster changes that occurred after dropping the
+		 * dlm spinlock would be detectable be a change on the mle,
+		 * so we only need to clear out the recovery map once. */
+		if (dlm_is_recovery_lock(lockid, namelen)) {
+			mlog(0, "%s: Recovery map is not empty, but must "
+			     "master $RECOVERY lock now\n", dlm->name);
+			if (!dlm_pre_master_reco_lockres(dlm, res))
+				wait_on_recovery = 0;
+			else {
+				mlog(0, "%s: waiting 500ms for heartbeat state "
+				    "change\n", dlm->name);
+				msleep(500);
+			}
+			continue;
+		}
+
+		dlm_kick_recovery_thread(dlm);
+		msleep(1000);
+		dlm_wait_for_recovery(dlm);
+
+		spin_lock(&dlm->spinlock);
+		bit = find_first_bit(dlm->recovery_map, O2NM_MAX_NODES);
+		if (bit < O2NM_MAX_NODES) {
+			mlog(0, "%s: res %.*s, At least one node (%d) "
+			     "to recover before lock mastery can begin\n",
+			     dlm->name, namelen, (char *)lockid, bit);
+			wait_on_recovery = 1;
+		} else
+			wait_on_recovery = 0;
+		spin_unlock(&dlm->spinlock);
+
+		if (wait_on_recovery)
+			dlm_wait_for_node_recovery(dlm, bit, 10000);
+	}
+
+	/* must wait for lock to be mastered elsewhere */
+	if (blocked)
+		goto wait;
+
+	ret = -EINVAL;
+	dlm_node_iter_init(mle->vote_map, &iter);
+	while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
+		ret = dlm_do_master_request(res, mle, nodenum);
+		if (ret < 0)
+			mlog_errno(ret);
+		if (mle->master != O2NM_MAX_NODES) {
+			/* found a master ! */
+			if (mle->master <= nodenum)
+				break;
+			/* if our master request has not reached the master
+			 * yet, keep going until it does.  this is how the
+			 * master will know that asserts are needed back to
+			 * the lower nodes. */
+			mlog(0, "%s: res %.*s, Requests only up to %u but "
+			     "master is %u, keep going\n", dlm->name, namelen,
+			     lockid, nodenum, mle->master);
+		}
+	}
+
+wait:
+	/* keep going until the response map includes all nodes */
+	ret = dlm_wait_for_lock_mastery(dlm, res, mle, &blocked);
+	if (ret < 0) {
+		wait_on_recovery = 1;
+		mlog(0, "%s: res %.*s, Node map changed, redo the master "
+		     "request now, blocked=%d\n", dlm->name, res->lockname.len,
+		     res->lockname.name, blocked);
+		if (++tries > 20) {
+			mlog(ML_ERROR, "%s: res %.*s, Spinning on "
+			     "dlm_wait_for_lock_mastery, blocked = %d\n",
+			     dlm->name, res->lockname.len,
+			     res->lockname.name, blocked);
+			dlm_print_one_lock_resource(res);
+			dlm_print_one_mle(mle);
+			tries = 0;
+		}
+		goto redo_request;
+	}
+
+	mlog(0, "%s: res %.*s, Mastered by %u\n", dlm->name, res->lockname.len,
+	     res->lockname.name, res->owner);
+	/* make sure we never continue without this */
+	BUG_ON(res->owner == O2NM_MAX_NODES);
+
+	/* master is known, detach if not already detached */
+	dlm_mle_detach_hb_events(dlm, mle);
+	dlm_put_mle(mle);
+	/* put the extra ref */
+	dlm_put_mle_inuse(mle);
+
+wake_waiters:
+	spin_lock(&res->spinlock);
+	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+leave:
+	/* need to free the unused mle */
+	if (alloc_mle)
+		kmem_cache_free(dlm_mle_cache, alloc_mle);
+
+	return res;
+}
+
+
+#define DLM_MASTERY_TIMEOUT_MS   5000
+
+static int dlm_wait_for_lock_mastery(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     struct dlm_master_list_entry *mle,
+				     int *blocked)
+{
+	u8 m;
+	int ret, bit;
+	int map_changed, voting_done;
+	int assert, sleep;
+
+recheck:
+	ret = 0;
+	assert = 0;
+
+	/* check if another node has already become the owner */
+	spin_lock(&res->spinlock);
+	if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
+		mlog(0, "%s:%.*s: owner is suddenly %u\n", dlm->name,
+		     res->lockname.len, res->lockname.name, res->owner);
+		spin_unlock(&res->spinlock);
+		/* this will cause the master to re-assert across
+		 * the whole cluster, freeing up mles */
+		if (res->owner != dlm->node_num) {
+			ret = dlm_do_master_request(res, mle, res->owner);
+			if (ret < 0) {
+				/* give recovery a chance to run */
+				mlog(ML_ERROR, "link to %u went down?: %d\n", res->owner, ret);
+				msleep(500);
+				goto recheck;
+			}
+		}
+		ret = 0;
+		goto leave;
+	}
+	spin_unlock(&res->spinlock);
+
+	spin_lock(&mle->spinlock);
+	m = mle->master;
+	map_changed = (memcmp(mle->vote_map, mle->node_map,
+			      sizeof(mle->vote_map)) != 0);
+	voting_done = (memcmp(mle->vote_map, mle->response_map,
+			     sizeof(mle->vote_map)) == 0);
+
+	/* restart if we hit any errors */
+	if (map_changed) {
+		int b;
+		mlog(0, "%s: %.*s: node map changed, restarting\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		ret = dlm_restart_lock_mastery(dlm, res, mle, *blocked);
+		b = (mle->type == DLM_MLE_BLOCK);
+		if ((*blocked && !b) || (!*blocked && b)) {
+			mlog(0, "%s:%.*s: status change: old=%d new=%d\n",
+			     dlm->name, res->lockname.len, res->lockname.name,
+			     *blocked, b);
+			*blocked = b;
+		}
+		spin_unlock(&mle->spinlock);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto leave;
+		}
+		mlog(0, "%s:%.*s: restart lock mastery succeeded, "
+		     "rechecking now\n", dlm->name, res->lockname.len,
+		     res->lockname.name);
+		goto recheck;
+	} else {
+		if (!voting_done) {
+			mlog(0, "map not changed and voting not done "
+			     "for %s:%.*s\n", dlm->name, res->lockname.len,
+			     res->lockname.name);
+		}
+	}
+
+	if (m != O2NM_MAX_NODES) {
+		/* another node has done an assert!
+		 * all done! */
+		sleep = 0;
+	} else {
+		sleep = 1;
+		/* have all nodes responded? */
+		if (voting_done && !*blocked) {
+			bit = find_first_bit(mle->maybe_map, O2NM_MAX_NODES);
+			if (dlm->node_num <= bit) {
+				/* my node number is lowest.
+			 	 * now tell other nodes that I am
+				 * mastering this. */
+				mle->master = dlm->node_num;
+				/* ref was grabbed in get_lock_resource
+				 * will be dropped in dlmlock_master */
+				assert = 1;
+				sleep = 0;
+			}
+			/* if voting is done, but we have not received
+			 * an assert master yet, we must sleep */
+		}
+	}
+
+	spin_unlock(&mle->spinlock);
+
+	/* sleep if we haven't finished voting yet */
+	if (sleep) {
+		unsigned long timeo = msecs_to_jiffies(DLM_MASTERY_TIMEOUT_MS);
+		atomic_set(&mle->woken, 0);
+		(void)wait_event_timeout(mle->wq,
+					 (atomic_read(&mle->woken) == 1),
+					 timeo);
+		if (res->owner == O2NM_MAX_NODES) {
+			mlog(0, "%s:%.*s: waiting again\n", dlm->name,
+			     res->lockname.len, res->lockname.name);
+			goto recheck;
+		}
+		mlog(0, "done waiting, master is %u\n", res->owner);
+		ret = 0;
+		goto leave;
+	}
+
+	ret = 0;   /* done */
+	if (assert) {
+		m = dlm->node_num;
+		mlog(0, "about to master %.*s here, this=%u\n",
+		     res->lockname.len, res->lockname.name, m);
+		ret = dlm_do_assert_master(dlm, res, mle->vote_map, 0);
+		if (ret) {
+			/* This is a failure in the network path,
+			 * not in the response to the assert_master
+			 * (any nonzero response is a BUG on this node).
+			 * Most likely a socket just got disconnected
+			 * due to node death. */
+			mlog_errno(ret);
+		}
+		/* no longer need to restart lock mastery.
+		 * all living nodes have been contacted. */
+		ret = 0;
+	}
+
+	/* set the lockres owner */
+	spin_lock(&res->spinlock);
+	/* mastery reference obtained either during
+	 * assert_master_handler or in get_lock_resource */
+	dlm_change_lockres_owner(dlm, res, m);
+	spin_unlock(&res->spinlock);
+
+leave:
+	return ret;
+}
+
+struct dlm_bitmap_diff_iter
+{
+	int curnode;
+	unsigned long *orig_bm;
+	unsigned long *cur_bm;
+	unsigned long diff_bm[BITS_TO_LONGS(O2NM_MAX_NODES)];
+};
+
+enum dlm_node_state_change
+{
+	NODE_DOWN = -1,
+	NODE_NO_CHANGE = 0,
+	NODE_UP
+};
+
+static void dlm_bitmap_diff_iter_init(struct dlm_bitmap_diff_iter *iter,
+				      unsigned long *orig_bm,
+				      unsigned long *cur_bm)
+{
+	unsigned long p1, p2;
+	int i;
+
+	iter->curnode = -1;
+	iter->orig_bm = orig_bm;
+	iter->cur_bm = cur_bm;
+
+	for (i = 0; i < BITS_TO_LONGS(O2NM_MAX_NODES); i++) {
+       		p1 = *(iter->orig_bm + i);
+	       	p2 = *(iter->cur_bm + i);
+		iter->diff_bm[i] = (p1 & ~p2) | (p2 & ~p1);
+	}
+}
+
+static int dlm_bitmap_diff_iter_next(struct dlm_bitmap_diff_iter *iter,
+				     enum dlm_node_state_change *state)
+{
+	int bit;
+
+	if (iter->curnode >= O2NM_MAX_NODES)
+		return -ENOENT;
+
+	bit = find_next_bit(iter->diff_bm, O2NM_MAX_NODES,
+			    iter->curnode+1);
+	if (bit >= O2NM_MAX_NODES) {
+		iter->curnode = O2NM_MAX_NODES;
+		return -ENOENT;
+	}
+
+	/* if it was there in the original then this node died */
+	if (test_bit(bit, iter->orig_bm))
+		*state = NODE_DOWN;
+	else
+		*state = NODE_UP;
+
+	iter->curnode = bit;
+	return bit;
+}
+
+
+static int dlm_restart_lock_mastery(struct dlm_ctxt *dlm,
+				    struct dlm_lock_resource *res,
+				    struct dlm_master_list_entry *mle,
+				    int blocked)
+{
+	struct dlm_bitmap_diff_iter bdi;
+	enum dlm_node_state_change sc;
+	int node;
+	int ret = 0;
+
+	mlog(0, "something happened such that the "
+	     "master process may need to be restarted!\n");
+
+	assert_spin_locked(&mle->spinlock);
+
+	dlm_bitmap_diff_iter_init(&bdi, mle->vote_map, mle->node_map);
+	node = dlm_bitmap_diff_iter_next(&bdi, &sc);
+	while (node >= 0) {
+		if (sc == NODE_UP) {
+			/* a node came up.  clear any old vote from
+			 * the response map and set it in the vote map
+			 * then restart the mastery. */
+			mlog(ML_NOTICE, "node %d up while restarting\n", node);
+
+			/* redo the master request, but only for the new node */
+			mlog(0, "sending request to new node\n");
+			clear_bit(node, mle->response_map);
+			set_bit(node, mle->vote_map);
+		} else {
+			mlog(ML_ERROR, "node down! %d\n", node);
+			if (blocked) {
+				int lowest = find_first_bit(mle->maybe_map,
+						       O2NM_MAX_NODES);
+
+				/* act like it was never there */
+				clear_bit(node, mle->maybe_map);
+
+			       	if (node == lowest) {
+					mlog(0, "expected master %u died"
+					    " while this node was blocked "
+					    "waiting on it!\n", node);
+					lowest = find_next_bit(mle->maybe_map,
+						       	O2NM_MAX_NODES,
+						       	lowest+1);
+					if (lowest < O2NM_MAX_NODES) {
+						mlog(0, "%s:%.*s:still "
+						     "blocked. waiting on %u "
+						     "now\n", dlm->name,
+						     res->lockname.len,
+						     res->lockname.name,
+						     lowest);
+					} else {
+						/* mle is an MLE_BLOCK, but
+						 * there is now nothing left to
+						 * block on.  we need to return
+						 * all the way back out and try
+						 * again with an MLE_MASTER.
+						 * dlm_do_local_recovery_cleanup
+						 * has already run, so the mle
+						 * refcount is ok */
+						mlog(0, "%s:%.*s: no "
+						     "longer blocking. try to "
+						     "master this here\n",
+						     dlm->name,
+						     res->lockname.len,
+						     res->lockname.name);
+						mle->type = DLM_MLE_MASTER;
+						mle->mleres = res;
+					}
+				}
+			}
+
+			/* now blank out everything, as if we had never
+			 * contacted anyone */
+			memset(mle->maybe_map, 0, sizeof(mle->maybe_map));
+			memset(mle->response_map, 0, sizeof(mle->response_map));
+			/* reset the vote_map to the current node_map */
+			memcpy(mle->vote_map, mle->node_map,
+			       sizeof(mle->node_map));
+			/* put myself into the maybe map */
+			if (mle->type != DLM_MLE_BLOCK)
+				set_bit(dlm->node_num, mle->maybe_map);
+		}
+		ret = -EAGAIN;
+		node = dlm_bitmap_diff_iter_next(&bdi, &sc);
+	}
+	return ret;
+}
+
+
+/*
+ * DLM_MASTER_REQUEST_MSG
+ *
+ * returns: 0 on success,
+ *          -errno on a network error
+ *
+ * on error, the caller should assume the target node is "dead"
+ *
+ */
+
+static int dlm_do_master_request(struct dlm_lock_resource *res,
+				 struct dlm_master_list_entry *mle, int to)
+{
+	struct dlm_ctxt *dlm = mle->dlm;
+	struct dlm_master_request request;
+	int ret, response=0, resend;
+
+	memset(&request, 0, sizeof(request));
+	request.node_idx = dlm->node_num;
+
+	BUG_ON(mle->type == DLM_MLE_MIGRATION);
+
+	request.namelen = (u8)mle->mnamelen;
+	memcpy(request.name, mle->mname, request.namelen);
+
+again:
+	ret = o2net_send_message(DLM_MASTER_REQUEST_MSG, dlm->key, &request,
+				 sizeof(request), to, &response);
+	if (ret < 0)  {
+		if (ret == -ESRCH) {
+			/* should never happen */
+			mlog(ML_ERROR, "TCP stack not ready!\n");
+			BUG();
+		} else if (ret == -EINVAL) {
+			mlog(ML_ERROR, "bad args passed to o2net!\n");
+			BUG();
+		} else if (ret == -ENOMEM) {
+			mlog(ML_ERROR, "out of memory while trying to send "
+			     "network message!  retrying\n");
+			/* this is totally crude */
+			msleep(50);
+			goto again;
+		} else if (!dlm_is_host_down(ret)) {
+			/* not a network error. bad. */
+			mlog_errno(ret);
+			mlog(ML_ERROR, "unhandled error!");
+			BUG();
+		}
+		/* all other errors should be network errors,
+		 * and likely indicate node death */
+		mlog(ML_ERROR, "link to %d went down!\n", to);
+		goto out;
+	}
+
+	ret = 0;
+	resend = 0;
+	spin_lock(&mle->spinlock);
+	switch (response) {
+		case DLM_MASTER_RESP_YES:
+			set_bit(to, mle->response_map);
+			mlog(0, "node %u is the master, response=YES\n", to);
+			mlog(0, "%s:%.*s: master node %u now knows I have a "
+			     "reference\n", dlm->name, res->lockname.len,
+			     res->lockname.name, to);
+			mle->master = to;
+			break;
+		case DLM_MASTER_RESP_NO:
+			mlog(0, "node %u not master, response=NO\n", to);
+			set_bit(to, mle->response_map);
+			break;
+		case DLM_MASTER_RESP_MAYBE:
+			mlog(0, "node %u not master, response=MAYBE\n", to);
+			set_bit(to, mle->response_map);
+			set_bit(to, mle->maybe_map);
+			break;
+		case DLM_MASTER_RESP_ERROR:
+			mlog(0, "node %u hit an error, resending\n", to);
+			resend = 1;
+			response = 0;
+			break;
+		default:
+			mlog(ML_ERROR, "bad response! %u\n", response);
+			BUG();
+	}
+	spin_unlock(&mle->spinlock);
+	if (resend) {
+		/* this is also totally crude */
+		msleep(50);
+		goto again;
+	}
+
+out:
+	return ret;
+}
+
+/*
+ * locks that can be taken here:
+ * dlm->spinlock
+ * res->spinlock
+ * mle->spinlock
+ * dlm->master_list
+ *
+ * if possible, TRIM THIS DOWN!!!
+ */
+int dlm_master_request_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data)
+{
+	u8 response = DLM_MASTER_RESP_MAYBE;
+	struct dlm_ctxt *dlm = data;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_master_request *request = (struct dlm_master_request *) msg->buf;
+	struct dlm_master_list_entry *mle = NULL, *tmpmle = NULL;
+	char *name;
+	unsigned int namelen, hash;
+	int found, ret;
+	int set_maybe;
+	int dispatch_assert = 0;
+	int dispatched = 0;
+
+	if (!dlm_grab(dlm))
+		return DLM_MASTER_RESP_NO;
+
+	if (!dlm_domain_fully_joined(dlm)) {
+		response = DLM_MASTER_RESP_NO;
+		goto send_response;
+	}
+
+	name = request->name;
+	namelen = request->namelen;
+	hash = dlm_lockid_hash(name, namelen);
+
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		response = DLM_IVBUFLEN;
+		goto send_response;
+	}
+
+way_up_top:
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres(dlm, name, namelen, hash);
+	if (res) {
+		spin_unlock(&dlm->spinlock);
+
+		/* take care of the easy cases up front */
+		spin_lock(&res->spinlock);
+
+		/*
+		 * Right after dlm spinlock was released, dlm_thread could have
+		 * purged the lockres. Check if lockres got unhashed. If so
+		 * start over.
+		 */
+		if (hlist_unhashed(&res->hash_node)) {
+			spin_unlock(&res->spinlock);
+			dlm_lockres_put(res);
+			goto way_up_top;
+		}
+
+		if (res->state & (DLM_LOCK_RES_RECOVERING|
+				  DLM_LOCK_RES_MIGRATING)) {
+			spin_unlock(&res->spinlock);
+			mlog(0, "returning DLM_MASTER_RESP_ERROR since res is "
+			     "being recovered/migrated\n");
+			response = DLM_MASTER_RESP_ERROR;
+			if (mle)
+				kmem_cache_free(dlm_mle_cache, mle);
+			goto send_response;
+		}
+
+		if (res->owner == dlm->node_num) {
+			dlm_lockres_set_refmap_bit(dlm, res, request->node_idx);
+			spin_unlock(&res->spinlock);
+			response = DLM_MASTER_RESP_YES;
+			if (mle)
+				kmem_cache_free(dlm_mle_cache, mle);
+
+			/* this node is the owner.
+			 * there is some extra work that needs to
+			 * happen now.  the requesting node has
+			 * caused all nodes up to this one to
+			 * create mles.  this node now needs to
+			 * go back and clean those up. */
+			dispatch_assert = 1;
+			goto send_response;
+		} else if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
+			spin_unlock(&res->spinlock);
+			// mlog(0, "node %u is the master\n", res->owner);
+			response = DLM_MASTER_RESP_NO;
+			if (mle)
+				kmem_cache_free(dlm_mle_cache, mle);
+			goto send_response;
+		}
+
+		/* ok, there is no owner.  either this node is
+		 * being blocked, or it is actively trying to
+		 * master this lock. */
+		if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
+			mlog(ML_ERROR, "lock with no owner should be "
+			     "in-progress!\n");
+			BUG();
+		}
+
+		// mlog(0, "lockres is in progress...\n");
+		spin_lock(&dlm->master_lock);
+		found = dlm_find_mle(dlm, &tmpmle, name, namelen);
+		if (!found) {
+			mlog(ML_ERROR, "no mle found for this lock!\n");
+			BUG();
+		}
+		set_maybe = 1;
+		spin_lock(&tmpmle->spinlock);
+		if (tmpmle->type == DLM_MLE_BLOCK) {
+			// mlog(0, "this node is waiting for "
+			// "lockres to be mastered\n");
+			response = DLM_MASTER_RESP_NO;
+		} else if (tmpmle->type == DLM_MLE_MIGRATION) {
+			mlog(0, "node %u is master, but trying to migrate to "
+			     "node %u.\n", tmpmle->master, tmpmle->new_master);
+			if (tmpmle->master == dlm->node_num) {
+				mlog(ML_ERROR, "no owner on lockres, but this "
+				     "node is trying to migrate it to %u?!\n",
+				     tmpmle->new_master);
+				BUG();
+			} else {
+				/* the real master can respond on its own */
+				response = DLM_MASTER_RESP_NO;
+			}
+		} else if (tmpmle->master != DLM_LOCK_RES_OWNER_UNKNOWN) {
+			set_maybe = 0;
+			if (tmpmle->master == dlm->node_num) {
+				response = DLM_MASTER_RESP_YES;
+				/* this node will be the owner.
+				 * go back and clean the mles on any
+				 * other nodes */
+				dispatch_assert = 1;
+				dlm_lockres_set_refmap_bit(dlm, res,
+							   request->node_idx);
+			} else
+				response = DLM_MASTER_RESP_NO;
+		} else {
+			// mlog(0, "this node is attempting to "
+			// "master lockres\n");
+			response = DLM_MASTER_RESP_MAYBE;
+		}
+		if (set_maybe)
+			set_bit(request->node_idx, tmpmle->maybe_map);
+		spin_unlock(&tmpmle->spinlock);
+
+		spin_unlock(&dlm->master_lock);
+		spin_unlock(&res->spinlock);
+
+		/* keep the mle attached to heartbeat events */
+		dlm_put_mle(tmpmle);
+		if (mle)
+			kmem_cache_free(dlm_mle_cache, mle);
+		goto send_response;
+	}
+
+	/*
+	 * lockres doesn't exist on this node
+	 * if there is an MLE_BLOCK, return NO
+	 * if there is an MLE_MASTER, return MAYBE
+	 * otherwise, add an MLE_BLOCK, return NO
+	 */
+	spin_lock(&dlm->master_lock);
+	found = dlm_find_mle(dlm, &tmpmle, name, namelen);
+	if (!found) {
+		/* this lockid has never been seen on this node yet */
+		// mlog(0, "no mle found\n");
+		if (!mle) {
+			spin_unlock(&dlm->master_lock);
+			spin_unlock(&dlm->spinlock);
+
+			mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
+			if (!mle) {
+				response = DLM_MASTER_RESP_ERROR;
+				mlog_errno(-ENOMEM);
+				goto send_response;
+			}
+			goto way_up_top;
+		}
+
+		// mlog(0, "this is second time thru, already allocated, "
+		// "add the block.\n");
+		dlm_init_mle(mle, DLM_MLE_BLOCK, dlm, NULL, name, namelen);
+		set_bit(request->node_idx, mle->maybe_map);
+		__dlm_insert_mle(dlm, mle);
+		response = DLM_MASTER_RESP_NO;
+	} else {
+		spin_lock(&tmpmle->spinlock);
+		if (tmpmle->master == dlm->node_num) {
+			mlog(ML_ERROR, "no lockres, but an mle with this node as master!\n");
+			BUG();
+		}
+		if (tmpmle->type == DLM_MLE_BLOCK)
+			response = DLM_MASTER_RESP_NO;
+		else if (tmpmle->type == DLM_MLE_MIGRATION) {
+			mlog(0, "migration mle was found (%u->%u)\n",
+			     tmpmle->master, tmpmle->new_master);
+			/* real master can respond on its own */
+			response = DLM_MASTER_RESP_NO;
+		} else
+			response = DLM_MASTER_RESP_MAYBE;
+		set_bit(request->node_idx, tmpmle->maybe_map);
+		spin_unlock(&tmpmle->spinlock);
+	}
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+
+	if (found) {
+		/* keep the mle attached to heartbeat events */
+		dlm_put_mle(tmpmle);
+	}
+send_response:
+	/*
+	 * __dlm_lookup_lockres() grabbed a reference to this lockres.
+	 * The reference is released by dlm_assert_master_worker() under
+	 * the call to dlm_dispatch_assert_master().  If
+	 * dlm_assert_master_worker() isn't called, we drop it here.
+	 */
+	if (dispatch_assert) {
+		mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
+			     dlm->node_num, res->lockname.len, res->lockname.name);
+		spin_lock(&res->spinlock);
+		ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx,
+						 DLM_ASSERT_MASTER_MLE_CLEANUP);
+		if (ret < 0) {
+			mlog(ML_ERROR, "failed to dispatch assert master work\n");
+			response = DLM_MASTER_RESP_ERROR;
+			spin_unlock(&res->spinlock);
+			dlm_lockres_put(res);
+		} else {
+			dispatched = 1;
+			__dlm_lockres_grab_inflight_worker(dlm, res);
+			spin_unlock(&res->spinlock);
+		}
+	} else {
+		if (res)
+			dlm_lockres_put(res);
+	}
+
+	if (!dispatched)
+		dlm_put(dlm);
+	return response;
+}
+
+/*
+ * DLM_ASSERT_MASTER_MSG
+ */
+
+
+/*
+ * NOTE: this can be used for debugging
+ * can periodically run all locks owned by this node
+ * and re-assert across the cluster...
+ */
+static int dlm_do_assert_master(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res,
+				void *nodemap, u32 flags)
+{
+	struct dlm_assert_master assert;
+	int to, tmpret;
+	struct dlm_node_iter iter;
+	int ret = 0;
+	int reassert;
+	const char *lockname = res->lockname.name;
+	unsigned int namelen = res->lockname.len;
+
+	BUG_ON(namelen > O2NM_MAX_NAME_LEN);
+
+	spin_lock(&res->spinlock);
+	res->state |= DLM_LOCK_RES_SETREF_INPROG;
+	spin_unlock(&res->spinlock);
+
+again:
+	reassert = 0;
+
+	/* note that if this nodemap is empty, it returns 0 */
+	dlm_node_iter_init(nodemap, &iter);
+	while ((to = dlm_node_iter_next(&iter)) >= 0) {
+		int r = 0;
+		struct dlm_master_list_entry *mle = NULL;
+
+		mlog(0, "sending assert master to %d (%.*s)\n", to,
+		     namelen, lockname);
+		memset(&assert, 0, sizeof(assert));
+		assert.node_idx = dlm->node_num;
+		assert.namelen = namelen;
+		memcpy(assert.name, lockname, namelen);
+		assert.flags = cpu_to_be32(flags);
+
+		tmpret = o2net_send_message(DLM_ASSERT_MASTER_MSG, dlm->key,
+					    &assert, sizeof(assert), to, &r);
+		if (tmpret < 0) {
+			mlog(ML_ERROR, "Error %d when sending message %u (key "
+			     "0x%x) to node %u\n", tmpret,
+			     DLM_ASSERT_MASTER_MSG, dlm->key, to);
+			if (!dlm_is_host_down(tmpret)) {
+				mlog(ML_ERROR, "unhandled error=%d!\n", tmpret);
+				BUG();
+			}
+			/* a node died.  finish out the rest of the nodes. */
+			mlog(0, "link to %d went down!\n", to);
+			/* any nonzero status return will do */
+			ret = tmpret;
+			r = 0;
+		} else if (r < 0) {
+			/* ok, something horribly messed.  kill thyself. */
+			mlog(ML_ERROR,"during assert master of %.*s to %u, "
+			     "got %d.\n", namelen, lockname, to, r);
+			spin_lock(&dlm->spinlock);
+			spin_lock(&dlm->master_lock);
+			if (dlm_find_mle(dlm, &mle, (char *)lockname,
+					 namelen)) {
+				dlm_print_one_mle(mle);
+				__dlm_put_mle(mle);
+			}
+			spin_unlock(&dlm->master_lock);
+			spin_unlock(&dlm->spinlock);
+			BUG();
+		}
+
+		if (r & DLM_ASSERT_RESPONSE_REASSERT &&
+		    !(r & DLM_ASSERT_RESPONSE_MASTERY_REF)) {
+				mlog(ML_ERROR, "%.*s: very strange, "
+				     "master MLE but no lockres on %u\n",
+				     namelen, lockname, to);
+		}
+
+		if (r & DLM_ASSERT_RESPONSE_REASSERT) {
+			mlog(0, "%.*s: node %u create mles on other "
+			     "nodes and requests a re-assert\n",
+			     namelen, lockname, to);
+			reassert = 1;
+		}
+		if (r & DLM_ASSERT_RESPONSE_MASTERY_REF) {
+			mlog(0, "%.*s: node %u has a reference to this "
+			     "lockres, set the bit in the refmap\n",
+			     namelen, lockname, to);
+			spin_lock(&res->spinlock);
+			dlm_lockres_set_refmap_bit(dlm, res, to);
+			spin_unlock(&res->spinlock);
+		}
+	}
+
+	if (reassert)
+		goto again;
+
+	spin_lock(&res->spinlock);
+	res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+	return ret;
+}
+
+/*
+ * locks that can be taken here:
+ * dlm->spinlock
+ * res->spinlock
+ * mle->spinlock
+ * dlm->master_list
+ *
+ * if possible, TRIM THIS DOWN!!!
+ */
+int dlm_assert_master_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_master_list_entry *mle = NULL;
+	struct dlm_assert_master *assert = (struct dlm_assert_master *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	char *name;
+	unsigned int namelen, hash;
+	u32 flags;
+	int master_request = 0, have_lockres_ref = 0;
+	int ret = 0;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	name = assert->name;
+	namelen = assert->namelen;
+	hash = dlm_lockid_hash(name, namelen);
+	flags = be32_to_cpu(assert->flags);
+
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		mlog(ML_ERROR, "Invalid name length!");
+		goto done;
+	}
+
+	spin_lock(&dlm->spinlock);
+
+	if (flags)
+		mlog(0, "assert_master with flags: %u\n", flags);
+
+	/* find the MLE */
+	spin_lock(&dlm->master_lock);
+	if (!dlm_find_mle(dlm, &mle, name, namelen)) {
+		/* not an error, could be master just re-asserting */
+		mlog(0, "just got an assert_master from %u, but no "
+		     "MLE for it! (%.*s)\n", assert->node_idx,
+		     namelen, name);
+	} else {
+		int bit = find_first_bit(mle->maybe_map, O2NM_MAX_NODES);
+		if (bit >= O2NM_MAX_NODES) {
+			/* not necessarily an error, though less likely.
+			 * could be master just re-asserting. */
+			mlog(0, "no bits set in the maybe_map, but %u "
+			     "is asserting! (%.*s)\n", assert->node_idx,
+			     namelen, name);
+		} else if (bit != assert->node_idx) {
+			if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
+				mlog(0, "master %u was found, %u should "
+				     "back off\n", assert->node_idx, bit);
+			} else {
+				/* with the fix for bug 569, a higher node
+				 * number winning the mastery will respond
+				 * YES to mastery requests, but this node
+				 * had no way of knowing.  let it pass. */
+				mlog(0, "%u is the lowest node, "
+				     "%u is asserting. (%.*s)  %u must "
+				     "have begun after %u won.\n", bit,
+				     assert->node_idx, namelen, name, bit,
+				     assert->node_idx);
+			}
+		}
+		if (mle->type == DLM_MLE_MIGRATION) {
+			if (flags & DLM_ASSERT_MASTER_MLE_CLEANUP) {
+				mlog(0, "%s:%.*s: got cleanup assert"
+				     " from %u for migration\n",
+				     dlm->name, namelen, name,
+				     assert->node_idx);
+			} else if (!(flags & DLM_ASSERT_MASTER_FINISH_MIGRATION)) {
+				mlog(0, "%s:%.*s: got unrelated assert"
+				     " from %u for migration, ignoring\n",
+				     dlm->name, namelen, name,
+				     assert->node_idx);
+				__dlm_put_mle(mle);
+				spin_unlock(&dlm->master_lock);
+				spin_unlock(&dlm->spinlock);
+				goto done;
+			}
+		}
+	}
+	spin_unlock(&dlm->master_lock);
+
+	/* ok everything checks out with the MLE
+	 * now check to see if there is a lockres */
+	res = __dlm_lookup_lockres(dlm, name, namelen, hash);
+	if (res) {
+		spin_lock(&res->spinlock);
+		if (res->state & DLM_LOCK_RES_RECOVERING)  {
+			mlog(ML_ERROR, "%u asserting but %.*s is "
+			     "RECOVERING!\n", assert->node_idx, namelen, name);
+			goto kill;
+		}
+		if (!mle) {
+			if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN &&
+			    res->owner != assert->node_idx) {
+				mlog(ML_ERROR, "DIE! Mastery assert from %u, "
+				     "but current owner is %u! (%.*s)\n",
+				     assert->node_idx, res->owner, namelen,
+				     name);
+				__dlm_print_one_lock_resource(res);
+				BUG();
+			}
+		} else if (mle->type != DLM_MLE_MIGRATION) {
+			if (res->owner != DLM_LOCK_RES_OWNER_UNKNOWN) {
+				/* owner is just re-asserting */
+				if (res->owner == assert->node_idx) {
+					mlog(0, "owner %u re-asserting on "
+					     "lock %.*s\n", assert->node_idx,
+					     namelen, name);
+					goto ok;
+				}
+				mlog(ML_ERROR, "got assert_master from "
+				     "node %u, but %u is the owner! "
+				     "(%.*s)\n", assert->node_idx,
+				     res->owner, namelen, name);
+				goto kill;
+			}
+			if (!(res->state & DLM_LOCK_RES_IN_PROGRESS)) {
+				mlog(ML_ERROR, "got assert from %u, but lock "
+				     "with no owner should be "
+				     "in-progress! (%.*s)\n",
+				     assert->node_idx,
+				     namelen, name);
+				goto kill;
+			}
+		} else /* mle->type == DLM_MLE_MIGRATION */ {
+			/* should only be getting an assert from new master */
+			if (assert->node_idx != mle->new_master) {
+				mlog(ML_ERROR, "got assert from %u, but "
+				     "new master is %u, and old master "
+				     "was %u (%.*s)\n",
+				     assert->node_idx, mle->new_master,
+				     mle->master, namelen, name);
+				goto kill;
+			}
+
+		}
+ok:
+		spin_unlock(&res->spinlock);
+	}
+
+	// mlog(0, "woo!  got an assert_master from node %u!\n",
+	// 	     assert->node_idx);
+	if (mle) {
+		int extra_ref = 0;
+		int nn = -1;
+		int rr, err = 0;
+
+		spin_lock(&mle->spinlock);
+		if (mle->type == DLM_MLE_BLOCK || mle->type == DLM_MLE_MIGRATION)
+			extra_ref = 1;
+		else {
+			/* MASTER mle: if any bits set in the response map
+			 * then the calling node needs to re-assert to clear
+			 * up nodes that this node contacted */
+			while ((nn = find_next_bit (mle->response_map, O2NM_MAX_NODES,
+						    nn+1)) < O2NM_MAX_NODES) {
+				if (nn != dlm->node_num && nn != assert->node_idx) {
+					master_request = 1;
+					break;
+				}
+			}
+		}
+		mle->master = assert->node_idx;
+		atomic_set(&mle->woken, 1);
+		wake_up(&mle->wq);
+		spin_unlock(&mle->spinlock);
+
+		if (res) {
+			int wake = 0;
+			spin_lock(&res->spinlock);
+			if (mle->type == DLM_MLE_MIGRATION) {
+				mlog(0, "finishing off migration of lockres %.*s, "
+			     		"from %u to %u\n",
+			       		res->lockname.len, res->lockname.name,
+			       		dlm->node_num, mle->new_master);
+				res->state &= ~DLM_LOCK_RES_MIGRATING;
+				wake = 1;
+				dlm_change_lockres_owner(dlm, res, mle->new_master);
+				BUG_ON(res->state & DLM_LOCK_RES_DIRTY);
+			} else {
+				dlm_change_lockres_owner(dlm, res, mle->master);
+			}
+			spin_unlock(&res->spinlock);
+			have_lockres_ref = 1;
+			if (wake)
+				wake_up(&res->wq);
+		}
+
+		/* master is known, detach if not already detached.
+		 * ensures that only one assert_master call will happen
+		 * on this mle. */
+		spin_lock(&dlm->master_lock);
+
+		rr = kref_read(&mle->mle_refs);
+		if (mle->inuse > 0) {
+			if (extra_ref && rr < 3)
+				err = 1;
+			else if (!extra_ref && rr < 2)
+				err = 1;
+		} else {
+			if (extra_ref && rr < 2)
+				err = 1;
+			else if (!extra_ref && rr < 1)
+				err = 1;
+		}
+		if (err) {
+			mlog(ML_ERROR, "%s:%.*s: got assert master from %u "
+			     "that will mess up this node, refs=%d, extra=%d, "
+			     "inuse=%d\n", dlm->name, namelen, name,
+			     assert->node_idx, rr, extra_ref, mle->inuse);
+			dlm_print_one_mle(mle);
+		}
+		__dlm_unlink_mle(dlm, mle);
+		__dlm_mle_detach_hb_events(dlm, mle);
+		__dlm_put_mle(mle);
+		if (extra_ref) {
+			/* the assert master message now balances the extra
+		 	 * ref given by the master / migration request message.
+		 	 * if this is the last put, it will be removed
+		 	 * from the list. */
+			__dlm_put_mle(mle);
+		}
+		spin_unlock(&dlm->master_lock);
+	} else if (res) {
+		if (res->owner != assert->node_idx) {
+			mlog(0, "assert_master from %u, but current "
+			     "owner is %u (%.*s), no mle\n", assert->node_idx,
+			     res->owner, namelen, name);
+		}
+	}
+	spin_unlock(&dlm->spinlock);
+
+done:
+	ret = 0;
+	if (res) {
+		spin_lock(&res->spinlock);
+		res->state |= DLM_LOCK_RES_SETREF_INPROG;
+		spin_unlock(&res->spinlock);
+		*ret_data = (void *)res;
+	}
+	dlm_put(dlm);
+	if (master_request) {
+		mlog(0, "need to tell master to reassert\n");
+		/* positive. negative would shoot down the node. */
+		ret |= DLM_ASSERT_RESPONSE_REASSERT;
+		if (!have_lockres_ref) {
+			mlog(ML_ERROR, "strange, got assert from %u, MASTER "
+			     "mle present here for %s:%.*s, but no lockres!\n",
+			     assert->node_idx, dlm->name, namelen, name);
+		}
+	}
+	if (have_lockres_ref) {
+		/* let the master know we have a reference to the lockres */
+		ret |= DLM_ASSERT_RESPONSE_MASTERY_REF;
+		mlog(0, "%s:%.*s: got assert from %u, need a ref\n",
+		     dlm->name, namelen, name, assert->node_idx);
+	}
+	return ret;
+
+kill:
+	/* kill the caller! */
+	mlog(ML_ERROR, "Bad message received from another node.  Dumping state "
+	     "and killing the other node now!  This node is OK and can continue.\n");
+	__dlm_print_one_lock_resource(res);
+	spin_unlock(&res->spinlock);
+	spin_lock(&dlm->master_lock);
+	if (mle)
+		__dlm_put_mle(mle);
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+	*ret_data = (void *)res;
+	dlm_put(dlm);
+	return -EINVAL;
+}
+
+void dlm_assert_master_post_handler(int status, void *data, void *ret_data)
+{
+	struct dlm_lock_resource *res = (struct dlm_lock_resource *)ret_data;
+
+	if (ret_data) {
+		spin_lock(&res->spinlock);
+		res->state &= ~DLM_LOCK_RES_SETREF_INPROG;
+		spin_unlock(&res->spinlock);
+		wake_up(&res->wq);
+		dlm_lockres_put(res);
+	}
+	return;
+}
+
+int dlm_dispatch_assert_master(struct dlm_ctxt *dlm,
+			       struct dlm_lock_resource *res,
+			       int ignore_higher, u8 request_from, u32 flags)
+{
+	struct dlm_work_item *item;
+	item = kzalloc(sizeof(*item), GFP_ATOMIC);
+	if (!item)
+		return -ENOMEM;
+
+
+	/* queue up work for dlm_assert_master_worker */
+	dlm_init_work_item(dlm, item, dlm_assert_master_worker, NULL);
+	item->u.am.lockres = res; /* already have a ref */
+	/* can optionally ignore node numbers higher than this node */
+	item->u.am.ignore_higher = ignore_higher;
+	item->u.am.request_from = request_from;
+	item->u.am.flags = flags;
+
+	if (ignore_higher)
+		mlog(0, "IGNORE HIGHER: %.*s\n", res->lockname.len,
+		     res->lockname.name);
+
+	spin_lock(&dlm->work_lock);
+	list_add_tail(&item->list, &dlm->work_list);
+	spin_unlock(&dlm->work_lock);
+
+	queue_work(dlm->dlm_worker, &dlm->dispatched_work);
+	return 0;
+}
+
+static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
+{
+	struct dlm_ctxt *dlm = data;
+	int ret = 0;
+	struct dlm_lock_resource *res;
+	unsigned long nodemap[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	int ignore_higher;
+	int bit;
+	u8 request_from;
+	u32 flags;
+
+	dlm = item->dlm;
+	res = item->u.am.lockres;
+	ignore_higher = item->u.am.ignore_higher;
+	request_from = item->u.am.request_from;
+	flags = item->u.am.flags;
+
+	spin_lock(&dlm->spinlock);
+	memcpy(nodemap, dlm->domain_map, sizeof(nodemap));
+	spin_unlock(&dlm->spinlock);
+
+	clear_bit(dlm->node_num, nodemap);
+	if (ignore_higher) {
+		/* if is this just to clear up mles for nodes below
+		 * this node, do not send the message to the original
+		 * caller or any node number higher than this */
+		clear_bit(request_from, nodemap);
+		bit = dlm->node_num;
+		while (1) {
+			bit = find_next_bit(nodemap, O2NM_MAX_NODES,
+					    bit+1);
+		       	if (bit >= O2NM_MAX_NODES)
+				break;
+			clear_bit(bit, nodemap);
+		}
+	}
+
+	/*
+	 * If we're migrating this lock to someone else, we are no
+	 * longer allowed to assert out own mastery.  OTOH, we need to
+	 * prevent migration from starting while we're still asserting
+	 * our dominance.  The reserved ast delays migration.
+	 */
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_MIGRATING) {
+		mlog(0, "Someone asked us to assert mastery, but we're "
+		     "in the middle of migration.  Skipping assert, "
+		     "the new master will handle that.\n");
+		spin_unlock(&res->spinlock);
+		goto put;
+	} else
+		__dlm_lockres_reserve_ast(res);
+	spin_unlock(&res->spinlock);
+
+	/* this call now finishes out the nodemap
+	 * even if one or more nodes die */
+	mlog(0, "worker about to master %.*s here, this=%u\n",
+		     res->lockname.len, res->lockname.name, dlm->node_num);
+	ret = dlm_do_assert_master(dlm, res, nodemap, flags);
+	if (ret < 0) {
+		/* no need to restart, we are done */
+		if (!dlm_is_host_down(ret))
+			mlog_errno(ret);
+	}
+
+	/* Ok, we've asserted ourselves.  Let's let migration start. */
+	dlm_lockres_release_ast(dlm, res);
+
+put:
+	dlm_lockres_drop_inflight_worker(dlm, res);
+
+	dlm_lockres_put(res);
+
+	mlog(0, "finished with dlm_assert_master_worker\n");
+}
+
+/* SPECIAL CASE for the $RECOVERY lock used by the recovery thread.
+ * We cannot wait for node recovery to complete to begin mastering this
+ * lockres because this lockres is used to kick off recovery! ;-)
+ * So, do a pre-check on all living nodes to see if any of those nodes
+ * think that $RECOVERY is currently mastered by a dead node.  If so,
+ * we wait a short time to allow that node to get notified by its own
+ * heartbeat stack, then check again.  All $RECOVERY lock resources
+ * mastered by dead nodes are purged when the heartbeat callback is
+ * fired, so we can know for sure that it is safe to continue once
+ * the node returns a live node or no node.  */
+static int dlm_pre_master_reco_lockres(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res)
+{
+	struct dlm_node_iter iter;
+	int nodenum;
+	int ret = 0;
+	u8 master = DLM_LOCK_RES_OWNER_UNKNOWN;
+
+	spin_lock(&dlm->spinlock);
+	dlm_node_iter_init(dlm->domain_map, &iter);
+	spin_unlock(&dlm->spinlock);
+
+	while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
+		/* do not send to self */
+		if (nodenum == dlm->node_num)
+			continue;
+		ret = dlm_do_master_requery(dlm, res, nodenum, &master);
+		if (ret < 0) {
+			mlog_errno(ret);
+			if (!dlm_is_host_down(ret))
+				BUG();
+			/* host is down, so answer for that node would be
+			 * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
+			ret = 0;
+		}
+
+		if (master != DLM_LOCK_RES_OWNER_UNKNOWN) {
+			/* check to see if this master is in the recovery map */
+			spin_lock(&dlm->spinlock);
+			if (test_bit(master, dlm->recovery_map)) {
+				mlog(ML_NOTICE, "%s: node %u has not seen "
+				     "node %u go down yet, and thinks the "
+				     "dead node is mastering the recovery "
+				     "lock.  must wait.\n", dlm->name,
+				     nodenum, master);
+				ret = -EAGAIN;
+			}
+			spin_unlock(&dlm->spinlock);
+			mlog(0, "%s: reco lock master is %u\n", dlm->name,
+			     master);
+			break;
+		}
+	}
+	return ret;
+}
+
+/*
+ * DLM_DEREF_LOCKRES_MSG
+ */
+
+int dlm_drop_lockres_ref(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+	struct dlm_deref_lockres deref;
+	int ret = 0, r;
+	const char *lockname;
+	unsigned int namelen;
+
+	lockname = res->lockname.name;
+	namelen = res->lockname.len;
+	BUG_ON(namelen > O2NM_MAX_NAME_LEN);
+
+	memset(&deref, 0, sizeof(deref));
+	deref.node_idx = dlm->node_num;
+	deref.namelen = namelen;
+	memcpy(deref.name, lockname, namelen);
+
+	ret = o2net_send_message(DLM_DEREF_LOCKRES_MSG, dlm->key,
+				 &deref, sizeof(deref), res->owner, &r);
+	if (ret < 0)
+		mlog(ML_ERROR, "%s: res %.*s, error %d send DEREF to node %u\n",
+		     dlm->name, namelen, lockname, ret, res->owner);
+	else if (r < 0) {
+		/* BAD.  other node says I did not have a ref. */
+		mlog(ML_ERROR, "%s: res %.*s, DEREF to node %u got %d\n",
+		     dlm->name, namelen, lockname, res->owner, r);
+		dlm_print_one_lock_resource(res);
+		if (r == -ENOMEM)
+			BUG();
+	} else
+		ret = r;
+
+	return ret;
+}
+
+int dlm_deref_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_deref_lockres *deref = (struct dlm_deref_lockres *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	char *name;
+	unsigned int namelen;
+	int ret = -EINVAL;
+	u8 node;
+	unsigned int hash;
+	struct dlm_work_item *item;
+	int cleared = 0;
+	int dispatch = 0;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	name = deref->name;
+	namelen = deref->namelen;
+	node = deref->node_idx;
+
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		mlog(ML_ERROR, "Invalid name length!");
+		goto done;
+	}
+	if (deref->node_idx >= O2NM_MAX_NODES) {
+		mlog(ML_ERROR, "Invalid node number: %u\n", node);
+		goto done;
+	}
+
+	hash = dlm_lockid_hash(name, namelen);
+
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres_full(dlm, name, namelen, hash);
+	if (!res) {
+		spin_unlock(&dlm->spinlock);
+		mlog(ML_ERROR, "%s:%.*s: bad lockres name\n",
+		     dlm->name, namelen, name);
+		goto done;
+	}
+	spin_unlock(&dlm->spinlock);
+
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_SETREF_INPROG)
+		dispatch = 1;
+	else {
+		BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
+		if (test_bit(node, res->refmap)) {
+			dlm_lockres_clear_refmap_bit(dlm, res, node);
+			cleared = 1;
+		}
+	}
+	spin_unlock(&res->spinlock);
+
+	if (!dispatch) {
+		if (cleared)
+			dlm_lockres_calc_usage(dlm, res);
+		else {
+			mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
+		     	"but it is already dropped!\n", dlm->name,
+		     	res->lockname.len, res->lockname.name, node);
+			dlm_print_one_lock_resource(res);
+		}
+		ret = DLM_DEREF_RESPONSE_DONE;
+		goto done;
+	}
+
+	item = kzalloc(sizeof(*item), GFP_NOFS);
+	if (!item) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto done;
+	}
+
+	dlm_init_work_item(dlm, item, dlm_deref_lockres_worker, NULL);
+	item->u.dl.deref_res = res;
+	item->u.dl.deref_node = node;
+
+	spin_lock(&dlm->work_lock);
+	list_add_tail(&item->list, &dlm->work_list);
+	spin_unlock(&dlm->work_lock);
+
+	queue_work(dlm->dlm_worker, &dlm->dispatched_work);
+	return DLM_DEREF_RESPONSE_INPROG;
+
+done:
+	if (res)
+		dlm_lockres_put(res);
+	dlm_put(dlm);
+
+	return ret;
+}
+
+int dlm_deref_lockres_done_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_deref_lockres_done *deref
+			= (struct dlm_deref_lockres_done *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	char *name;
+	unsigned int namelen;
+	int ret = -EINVAL;
+	u8 node;
+	unsigned int hash;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	name = deref->name;
+	namelen = deref->namelen;
+	node = deref->node_idx;
+
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		mlog(ML_ERROR, "Invalid name length!");
+		goto done;
+	}
+	if (deref->node_idx >= O2NM_MAX_NODES) {
+		mlog(ML_ERROR, "Invalid node number: %u\n", node);
+		goto done;
+	}
+
+	hash = dlm_lockid_hash(name, namelen);
+
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres_full(dlm, name, namelen, hash);
+	if (!res) {
+		spin_unlock(&dlm->spinlock);
+		mlog(ML_ERROR, "%s:%.*s: bad lockres name\n",
+		     dlm->name, namelen, name);
+		goto done;
+	}
+
+	spin_lock(&res->spinlock);
+	if (!(res->state & DLM_LOCK_RES_DROPPING_REF)) {
+		spin_unlock(&res->spinlock);
+		spin_unlock(&dlm->spinlock);
+		mlog(ML_NOTICE, "%s:%.*s: node %u sends deref done "
+			"but it is already derefed!\n", dlm->name,
+			res->lockname.len, res->lockname.name, node);
+		ret = 0;
+		goto done;
+	}
+
+	__dlm_do_purge_lockres(dlm, res);
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+	spin_unlock(&dlm->spinlock);
+
+	ret = 0;
+done:
+	if (res)
+		dlm_lockres_put(res);
+	dlm_put(dlm);
+	return ret;
+}
+
+static void dlm_drop_lockres_ref_done(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res, u8 node)
+{
+	struct dlm_deref_lockres_done deref;
+	int ret = 0, r;
+	const char *lockname;
+	unsigned int namelen;
+
+	lockname = res->lockname.name;
+	namelen = res->lockname.len;
+	BUG_ON(namelen > O2NM_MAX_NAME_LEN);
+
+	memset(&deref, 0, sizeof(deref));
+	deref.node_idx = dlm->node_num;
+	deref.namelen = namelen;
+	memcpy(deref.name, lockname, namelen);
+
+	ret = o2net_send_message(DLM_DEREF_LOCKRES_DONE, dlm->key,
+				 &deref, sizeof(deref), node, &r);
+	if (ret < 0) {
+		mlog(ML_ERROR, "%s: res %.*s, error %d send DEREF DONE "
+				" to node %u\n", dlm->name, namelen,
+				lockname, ret, node);
+	} else if (r < 0) {
+		/* ignore the error */
+		mlog(ML_ERROR, "%s: res %.*s, DEREF to node %u got %d\n",
+		     dlm->name, namelen, lockname, node, r);
+		dlm_print_one_lock_resource(res);
+	}
+}
+
+static void dlm_deref_lockres_worker(struct dlm_work_item *item, void *data)
+{
+	struct dlm_ctxt *dlm;
+	struct dlm_lock_resource *res;
+	u8 node;
+	u8 cleared = 0;
+
+	dlm = item->dlm;
+	res = item->u.dl.deref_res;
+	node = item->u.dl.deref_node;
+
+	spin_lock(&res->spinlock);
+	BUG_ON(res->state & DLM_LOCK_RES_DROPPING_REF);
+	__dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
+	if (test_bit(node, res->refmap)) {
+		dlm_lockres_clear_refmap_bit(dlm, res, node);
+		cleared = 1;
+	}
+	spin_unlock(&res->spinlock);
+
+	dlm_drop_lockres_ref_done(dlm, res, node);
+
+	if (cleared) {
+		mlog(0, "%s:%.*s node %u ref dropped in dispatch\n",
+		     dlm->name, res->lockname.len, res->lockname.name, node);
+		dlm_lockres_calc_usage(dlm, res);
+	} else {
+		mlog(ML_ERROR, "%s:%.*s: node %u trying to drop ref "
+		     "but it is already dropped!\n", dlm->name,
+		     res->lockname.len, res->lockname.name, node);
+		dlm_print_one_lock_resource(res);
+	}
+
+	dlm_lockres_put(res);
+}
+
+/*
+ * A migratable resource is one that is :
+ * 1. locally mastered, and,
+ * 2. zero local locks, and,
+ * 3. one or more non-local locks, or, one or more references
+ * Returns 1 if yes, 0 if not.
+ */
+static int dlm_is_lockres_migratable(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res)
+{
+	enum dlm_lockres_list idx;
+	int nonlocal = 0, node_ref;
+	struct list_head *queue;
+	struct dlm_lock *lock;
+	u64 cookie;
+
+	assert_spin_locked(&res->spinlock);
+
+	/* delay migration when the lockres is in MIGRATING state */
+	if (res->state & DLM_LOCK_RES_MIGRATING)
+		return 0;
+
+	/* delay migration when the lockres is in RECOCERING state */
+	if (res->state & (DLM_LOCK_RES_RECOVERING|
+			DLM_LOCK_RES_RECOVERY_WAITING))
+		return 0;
+
+	if (res->owner != dlm->node_num)
+		return 0;
+
+        for (idx = DLM_GRANTED_LIST; idx <= DLM_BLOCKED_LIST; idx++) {
+		queue = dlm_list_idx_to_ptr(res, idx);
+		list_for_each_entry(lock, queue, list) {
+			if (lock->ml.node != dlm->node_num) {
+				nonlocal++;
+				continue;
+			}
+			cookie = be64_to_cpu(lock->ml.cookie);
+			mlog(0, "%s: Not migratable res %.*s, lock %u:%llu on "
+			     "%s list\n", dlm->name, res->lockname.len,
+			     res->lockname.name,
+			     dlm_get_lock_cookie_node(cookie),
+			     dlm_get_lock_cookie_seq(cookie),
+			     dlm_list_in_text(idx));
+			return 0;
+		}
+	}
+
+	if (!nonlocal) {
+		node_ref = find_first_bit(res->refmap, O2NM_MAX_NODES);
+		if (node_ref >= O2NM_MAX_NODES)
+			return 0;
+	}
+
+	mlog(0, "%s: res %.*s, Migratable\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+
+	return 1;
+}
+
+/*
+ * DLM_MIGRATE_LOCKRES
+ */
+
+
+static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
+			       struct dlm_lock_resource *res, u8 target)
+{
+	struct dlm_master_list_entry *mle = NULL;
+	struct dlm_master_list_entry *oldmle = NULL;
+ 	struct dlm_migratable_lockres *mres = NULL;
+	int ret = 0;
+	const char *name;
+	unsigned int namelen;
+	int mle_added = 0;
+	int wake = 0;
+
+	if (!dlm_grab(dlm))
+		return -EINVAL;
+
+	name = res->lockname.name;
+	namelen = res->lockname.len;
+
+	mlog(0, "%s: Migrating %.*s to node %u\n", dlm->name, namelen, name,
+	     target);
+
+	/* preallocate up front. if this fails, abort */
+	ret = -ENOMEM;
+	mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_NOFS);
+	if (!mres) {
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
+	if (!mle) {
+		mlog_errno(ret);
+		goto leave;
+	}
+	ret = 0;
+
+	/*
+	 * clear any existing master requests and
+	 * add the migration mle to the list
+	 */
+	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->master_lock);
+	ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
+				    namelen, target, dlm->node_num);
+	/* get an extra reference on the mle.
+	 * otherwise the assert_master from the new
+	 * master will destroy this.
+	 */
+	if (ret != -EEXIST)
+		dlm_get_mle_inuse(mle);
+
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+
+	if (ret == -EEXIST) {
+		mlog(0, "another process is already migrating it\n");
+		goto fail;
+	}
+	mle_added = 1;
+
+	/*
+	 * set the MIGRATING flag and flush asts
+	 * if we fail after this we need to re-dirty the lockres
+	 */
+	if (dlm_mark_lockres_migrating(dlm, res, target) < 0) {
+		mlog(ML_ERROR, "tried to migrate %.*s to %u, but "
+		     "the target went down.\n", res->lockname.len,
+		     res->lockname.name, target);
+		spin_lock(&res->spinlock);
+		res->state &= ~DLM_LOCK_RES_MIGRATING;
+		wake = 1;
+		spin_unlock(&res->spinlock);
+		ret = -EINVAL;
+	}
+
+fail:
+	if (ret != -EEXIST && oldmle) {
+		/* master is known, detach if not already detached */
+		dlm_mle_detach_hb_events(dlm, oldmle);
+		dlm_put_mle(oldmle);
+	}
+
+	if (ret < 0) {
+		if (mle_added) {
+			dlm_mle_detach_hb_events(dlm, mle);
+			dlm_put_mle(mle);
+			dlm_put_mle_inuse(mle);
+		} else if (mle) {
+			kmem_cache_free(dlm_mle_cache, mle);
+			mle = NULL;
+		}
+		goto leave;
+	}
+
+	/*
+	 * at this point, we have a migration target, an mle
+	 * in the master list, and the MIGRATING flag set on
+	 * the lockres
+	 */
+
+	/* now that remote nodes are spinning on the MIGRATING flag,
+	 * ensure that all assert_master work is flushed. */
+	flush_workqueue(dlm->dlm_worker);
+
+	/* notify new node and send all lock state */
+	/* call send_one_lockres with migration flag.
+	 * this serves as notice to the target node that a
+	 * migration is starting. */
+	ret = dlm_send_one_lockres(dlm, res, mres, target,
+				   DLM_MRES_MIGRATION);
+
+	if (ret < 0) {
+		mlog(0, "migration to node %u failed with %d\n",
+		     target, ret);
+		/* migration failed, detach and clean up mle */
+		dlm_mle_detach_hb_events(dlm, mle);
+		dlm_put_mle(mle);
+		dlm_put_mle_inuse(mle);
+		spin_lock(&res->spinlock);
+		res->state &= ~DLM_LOCK_RES_MIGRATING;
+		wake = 1;
+		spin_unlock(&res->spinlock);
+		if (dlm_is_host_down(ret))
+			dlm_wait_for_node_death(dlm, target,
+						DLM_NODE_DEATH_WAIT_MAX);
+		goto leave;
+	}
+
+	/* at this point, the target sends a message to all nodes,
+	 * (using dlm_do_migrate_request).  this node is skipped since
+	 * we had to put an mle in the list to begin the process.  this
+	 * node now waits for target to do an assert master.  this node
+	 * will be the last one notified, ensuring that the migration
+	 * is complete everywhere.  if the target dies while this is
+	 * going on, some nodes could potentially see the target as the
+	 * master, so it is important that my recovery finds the migration
+	 * mle and sets the master to UNKNOWN. */
+
+
+	/* wait for new node to assert master */
+	while (1) {
+		ret = wait_event_interruptible_timeout(mle->wq,
+					(atomic_read(&mle->woken) == 1),
+					msecs_to_jiffies(5000));
+
+		if (ret >= 0) {
+		       	if (atomic_read(&mle->woken) == 1 ||
+			    res->owner == target)
+				break;
+
+			mlog(0, "%s:%.*s: timed out during migration\n",
+			     dlm->name, res->lockname.len, res->lockname.name);
+			/* avoid hang during shutdown when migrating lockres
+			 * to a node which also goes down */
+			if (dlm_is_node_dead(dlm, target)) {
+				mlog(0, "%s:%.*s: expected migration "
+				     "target %u is no longer up, restarting\n",
+				     dlm->name, res->lockname.len,
+				     res->lockname.name, target);
+				ret = -EINVAL;
+				/* migration failed, detach and clean up mle */
+				dlm_mle_detach_hb_events(dlm, mle);
+				dlm_put_mle(mle);
+				dlm_put_mle_inuse(mle);
+				spin_lock(&res->spinlock);
+				res->state &= ~DLM_LOCK_RES_MIGRATING;
+				wake = 1;
+				spin_unlock(&res->spinlock);
+				goto leave;
+			}
+		} else
+			mlog(0, "%s:%.*s: caught signal during migration\n",
+			     dlm->name, res->lockname.len, res->lockname.name);
+	}
+
+	/* all done, set the owner, clear the flag */
+	spin_lock(&res->spinlock);
+	dlm_set_lockres_owner(dlm, res, target);
+	res->state &= ~DLM_LOCK_RES_MIGRATING;
+	dlm_remove_nonlocal_locks(dlm, res);
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+	/* master is known, detach if not already detached */
+	dlm_mle_detach_hb_events(dlm, mle);
+	dlm_put_mle_inuse(mle);
+	ret = 0;
+
+	dlm_lockres_calc_usage(dlm, res);
+
+leave:
+	/* re-dirty the lockres if we failed */
+	if (ret < 0)
+		dlm_kick_thread(dlm, res);
+
+	/* wake up waiters if the MIGRATING flag got set
+	 * but migration failed */
+	if (wake)
+		wake_up(&res->wq);
+
+	if (mres)
+		free_page((unsigned long)mres);
+
+	dlm_put(dlm);
+
+	mlog(0, "%s: Migrating %.*s to %u, returns %d\n", dlm->name, namelen,
+	     name, target, ret);
+	return ret;
+}
+
+/*
+ * Should be called only after beginning the domain leave process.
+ * There should not be any remaining locks on nonlocal lock resources,
+ * and there should be no local locks left on locally mastered resources.
+ *
+ * Called with the dlm spinlock held, may drop it to do migration, but
+ * will re-acquire before exit.
+ *
+ * Returns: 1 if dlm->spinlock was dropped/retaken, 0 if never dropped
+ */
+int dlm_empty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+	__must_hold(&dlm->spinlock)
+{
+	int ret;
+	int lock_dropped = 0;
+	u8 target = O2NM_MAX_NODES;
+
+	assert_spin_locked(&dlm->spinlock);
+
+	spin_lock(&res->spinlock);
+	if (dlm_is_lockres_migratable(dlm, res))
+		target = dlm_pick_migration_target(dlm, res);
+	spin_unlock(&res->spinlock);
+
+	if (target == O2NM_MAX_NODES)
+		goto leave;
+
+	/* Wheee! Migrate lockres here! Will sleep so drop spinlock. */
+	spin_unlock(&dlm->spinlock);
+	lock_dropped = 1;
+	ret = dlm_migrate_lockres(dlm, res, target);
+	if (ret)
+		mlog(0, "%s: res %.*s, Migrate to node %u failed with %d\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     target, ret);
+	spin_lock(&dlm->spinlock);
+leave:
+	return lock_dropped;
+}
+
+int dlm_lock_basts_flushed(struct dlm_ctxt *dlm, struct dlm_lock *lock)
+{
+	int ret;
+	spin_lock(&dlm->ast_lock);
+	spin_lock(&lock->spinlock);
+	ret = (list_empty(&lock->bast_list) && !lock->bast_pending);
+	spin_unlock(&lock->spinlock);
+	spin_unlock(&dlm->ast_lock);
+	return ret;
+}
+
+static int dlm_migration_can_proceed(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     u8 mig_target)
+{
+	int can_proceed;
+	spin_lock(&res->spinlock);
+	can_proceed = !!(res->state & DLM_LOCK_RES_MIGRATING);
+	spin_unlock(&res->spinlock);
+
+	/* target has died, so make the caller break out of the
+	 * wait_event, but caller must recheck the domain_map */
+	spin_lock(&dlm->spinlock);
+	if (!test_bit(mig_target, dlm->domain_map))
+		can_proceed = 1;
+	spin_unlock(&dlm->spinlock);
+	return can_proceed;
+}
+
+static int dlm_lockres_is_dirty(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res)
+{
+	int ret;
+	spin_lock(&res->spinlock);
+	ret = !!(res->state & DLM_LOCK_RES_DIRTY);
+	spin_unlock(&res->spinlock);
+	return ret;
+}
+
+
+static int dlm_mark_lockres_migrating(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res,
+				       u8 target)
+{
+	int ret = 0;
+
+	mlog(0, "dlm_mark_lockres_migrating: %.*s, from %u to %u\n",
+	       res->lockname.len, res->lockname.name, dlm->node_num,
+	       target);
+	/* need to set MIGRATING flag on lockres.  this is done by
+	 * ensuring that all asts have been flushed for this lockres. */
+	spin_lock(&res->spinlock);
+	BUG_ON(res->migration_pending);
+	res->migration_pending = 1;
+	/* strategy is to reserve an extra ast then release
+	 * it below, letting the release do all of the work */
+	__dlm_lockres_reserve_ast(res);
+	spin_unlock(&res->spinlock);
+
+	/* now flush all the pending asts */
+	dlm_kick_thread(dlm, res);
+	/* before waiting on DIRTY, block processes which may
+	 * try to dirty the lockres before MIGRATING is set */
+	spin_lock(&res->spinlock);
+	BUG_ON(res->state & DLM_LOCK_RES_BLOCK_DIRTY);
+	res->state |= DLM_LOCK_RES_BLOCK_DIRTY;
+	spin_unlock(&res->spinlock);
+	/* now wait on any pending asts and the DIRTY state */
+	wait_event(dlm->ast_wq, !dlm_lockres_is_dirty(dlm, res));
+	dlm_lockres_release_ast(dlm, res);
+
+	mlog(0, "about to wait on migration_wq, dirty=%s\n",
+	       res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
+	/* if the extra ref we just put was the final one, this
+	 * will pass thru immediately.  otherwise, we need to wait
+	 * for the last ast to finish. */
+again:
+	ret = wait_event_interruptible_timeout(dlm->migration_wq,
+		   dlm_migration_can_proceed(dlm, res, target),
+		   msecs_to_jiffies(1000));
+	if (ret < 0) {
+		mlog(0, "woken again: migrating? %s, dead? %s\n",
+		       res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
+		       test_bit(target, dlm->domain_map) ? "no":"yes");
+	} else {
+		mlog(0, "all is well: migrating? %s, dead? %s\n",
+		       res->state & DLM_LOCK_RES_MIGRATING ? "yes":"no",
+		       test_bit(target, dlm->domain_map) ? "no":"yes");
+	}
+	if (!dlm_migration_can_proceed(dlm, res, target)) {
+		mlog(0, "trying again...\n");
+		goto again;
+	}
+
+	ret = 0;
+	/* did the target go down or die? */
+	spin_lock(&dlm->spinlock);
+	if (!test_bit(target, dlm->domain_map)) {
+		mlog(ML_ERROR, "aha. migration target %u just went down\n",
+		     target);
+		ret = -EHOSTDOWN;
+	}
+	spin_unlock(&dlm->spinlock);
+
+	/*
+	 * if target is down, we need to clear DLM_LOCK_RES_BLOCK_DIRTY for
+	 * another try; otherwise, we are sure the MIGRATING state is there,
+	 * drop the unneeded state which blocked threads trying to DIRTY
+	 */
+	spin_lock(&res->spinlock);
+	BUG_ON(!(res->state & DLM_LOCK_RES_BLOCK_DIRTY));
+	res->state &= ~DLM_LOCK_RES_BLOCK_DIRTY;
+	if (!ret)
+		BUG_ON(!(res->state & DLM_LOCK_RES_MIGRATING));
+	else
+		res->migration_pending = 0;
+	spin_unlock(&res->spinlock);
+
+	/*
+	 * at this point:
+	 *
+	 *   o the DLM_LOCK_RES_MIGRATING flag is set if target not down
+	 *   o there are no pending asts on this lockres
+	 *   o all processes trying to reserve an ast on this
+	 *     lockres must wait for the MIGRATING flag to clear
+	 */
+	return ret;
+}
+
+/* last step in the migration process.
+ * original master calls this to free all of the dlm_lock
+ * structures that used to be for other nodes. */
+static void dlm_remove_nonlocal_locks(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res)
+{
+	struct list_head *queue = &res->granted;
+	int i, bit;
+	struct dlm_lock *lock, *next;
+
+	assert_spin_locked(&res->spinlock);
+
+	BUG_ON(res->owner == dlm->node_num);
+
+	for (i=0; i<3; i++) {
+		list_for_each_entry_safe(lock, next, queue, list) {
+			if (lock->ml.node != dlm->node_num) {
+				mlog(0, "putting lock for node %u\n",
+				     lock->ml.node);
+				/* be extra careful */
+				BUG_ON(!list_empty(&lock->ast_list));
+				BUG_ON(!list_empty(&lock->bast_list));
+				BUG_ON(lock->ast_pending);
+				BUG_ON(lock->bast_pending);
+				dlm_lockres_clear_refmap_bit(dlm, res,
+							     lock->ml.node);
+				list_del_init(&lock->list);
+				dlm_lock_put(lock);
+				/* In a normal unlock, we would have added a
+				 * DLM_UNLOCK_FREE_LOCK action. Force it. */
+				dlm_lock_put(lock);
+			}
+		}
+		queue++;
+	}
+	bit = 0;
+	while (1) {
+		bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
+		if (bit >= O2NM_MAX_NODES)
+			break;
+		/* do not clear the local node reference, if there is a
+		 * process holding this, let it drop the ref itself */
+		if (bit != dlm->node_num) {
+			mlog(0, "%s:%.*s: node %u had a ref to this "
+			     "migrating lockres, clearing\n", dlm->name,
+			     res->lockname.len, res->lockname.name, bit);
+			dlm_lockres_clear_refmap_bit(dlm, res, bit);
+		}
+		bit++;
+	}
+}
+
+/*
+ * Pick a node to migrate the lock resource to. This function selects a
+ * potential target based first on the locks and then on refmap. It skips
+ * nodes that are in the process of exiting the domain.
+ */
+static u8 dlm_pick_migration_target(struct dlm_ctxt *dlm,
+				    struct dlm_lock_resource *res)
+{
+	enum dlm_lockres_list idx;
+	struct list_head *queue;
+	struct dlm_lock *lock;
+	int noderef;
+	u8 nodenum = O2NM_MAX_NODES;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	/* Go through all the locks */
+	for (idx = DLM_GRANTED_LIST; idx <= DLM_BLOCKED_LIST; idx++) {
+		queue = dlm_list_idx_to_ptr(res, idx);
+		list_for_each_entry(lock, queue, list) {
+			if (lock->ml.node == dlm->node_num)
+				continue;
+			if (test_bit(lock->ml.node, dlm->exit_domain_map))
+				continue;
+			nodenum = lock->ml.node;
+			goto bail;
+		}
+	}
+
+	/* Go thru the refmap */
+	noderef = -1;
+	while (1) {
+		noderef = find_next_bit(res->refmap, O2NM_MAX_NODES,
+					noderef + 1);
+		if (noderef >= O2NM_MAX_NODES)
+			break;
+		if (noderef == dlm->node_num)
+			continue;
+		if (test_bit(noderef, dlm->exit_domain_map))
+			continue;
+		nodenum = noderef;
+		goto bail;
+	}
+
+bail:
+	return nodenum;
+}
+
+/* this is called by the new master once all lockres
+ * data has been received */
+static int dlm_do_migrate_request(struct dlm_ctxt *dlm,
+				  struct dlm_lock_resource *res,
+				  u8 master, u8 new_master,
+				  struct dlm_node_iter *iter)
+{
+	struct dlm_migrate_request migrate;
+	int ret, skip, status = 0;
+	int nodenum;
+
+	memset(&migrate, 0, sizeof(migrate));
+	migrate.namelen = res->lockname.len;
+	memcpy(migrate.name, res->lockname.name, migrate.namelen);
+	migrate.new_master = new_master;
+	migrate.master = master;
+
+	ret = 0;
+
+	/* send message to all nodes, except the master and myself */
+	while ((nodenum = dlm_node_iter_next(iter)) >= 0) {
+		if (nodenum == master ||
+		    nodenum == new_master)
+			continue;
+
+		/* We could race exit domain. If exited, skip. */
+		spin_lock(&dlm->spinlock);
+		skip = (!test_bit(nodenum, dlm->domain_map));
+		spin_unlock(&dlm->spinlock);
+		if (skip) {
+			clear_bit(nodenum, iter->node_map);
+			continue;
+		}
+
+		ret = o2net_send_message(DLM_MIGRATE_REQUEST_MSG, dlm->key,
+					 &migrate, sizeof(migrate), nodenum,
+					 &status);
+		if (ret < 0) {
+			mlog(ML_ERROR, "%s: res %.*s, Error %d send "
+			     "MIGRATE_REQUEST to node %u\n", dlm->name,
+			     migrate.namelen, migrate.name, ret, nodenum);
+			if (!dlm_is_host_down(ret)) {
+				mlog(ML_ERROR, "unhandled error=%d!\n", ret);
+				BUG();
+			}
+			clear_bit(nodenum, iter->node_map);
+			ret = 0;
+		} else if (status < 0) {
+			mlog(0, "migrate request (node %u) returned %d!\n",
+			     nodenum, status);
+			ret = status;
+		} else if (status == DLM_MIGRATE_RESPONSE_MASTERY_REF) {
+			/* during the migration request we short-circuited
+			 * the mastery of the lockres.  make sure we have
+			 * a mastery ref for nodenum */
+			mlog(0, "%s:%.*s: need ref for node %u\n",
+			     dlm->name, res->lockname.len, res->lockname.name,
+			     nodenum);
+			spin_lock(&res->spinlock);
+			dlm_lockres_set_refmap_bit(dlm, res, nodenum);
+			spin_unlock(&res->spinlock);
+		}
+	}
+
+	if (ret < 0)
+		mlog_errno(ret);
+
+	mlog(0, "returning ret=%d\n", ret);
+	return ret;
+}
+
+
+/* if there is an existing mle for this lockres, we now know who the master is.
+ * (the one who sent us *this* message) we can clear it up right away.
+ * since the process that put the mle on the list still has a reference to it,
+ * we can unhash it now, set the master and wake the process.  as a result,
+ * we will have no mle in the list to start with.  now we can add an mle for
+ * the migration and this should be the only one found for those scanning the
+ * list.  */
+int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
+				void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_migrate_request *migrate = (struct dlm_migrate_request *) msg->buf;
+	struct dlm_master_list_entry *mle = NULL, *oldmle = NULL;
+	const char *name;
+	unsigned int namelen, hash;
+	int ret = 0;
+
+	if (!dlm_grab(dlm))
+		return 0;
+
+	name = migrate->name;
+	namelen = migrate->namelen;
+	hash = dlm_lockid_hash(name, namelen);
+
+	/* preallocate.. if this fails, abort */
+	mle = kmem_cache_alloc(dlm_mle_cache, GFP_NOFS);
+
+	if (!mle) {
+		ret = -ENOMEM;
+		goto leave;
+	}
+
+	/* check for pre-existing lock */
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres(dlm, name, namelen, hash);
+	if (res) {
+		spin_lock(&res->spinlock);
+		if (res->state & DLM_LOCK_RES_RECOVERING) {
+			/* if all is working ok, this can only mean that we got
+		 	* a migrate request from a node that we now see as
+		 	* dead.  what can we do here?  drop it to the floor? */
+			spin_unlock(&res->spinlock);
+			mlog(ML_ERROR, "Got a migrate request, but the "
+			     "lockres is marked as recovering!");
+			kmem_cache_free(dlm_mle_cache, mle);
+			ret = -EINVAL; /* need a better solution */
+			goto unlock;
+		}
+		res->state |= DLM_LOCK_RES_MIGRATING;
+		spin_unlock(&res->spinlock);
+	}
+
+	spin_lock(&dlm->master_lock);
+	/* ignore status.  only nonzero status would BUG. */
+	ret = dlm_add_migration_mle(dlm, res, mle, &oldmle,
+				    name, namelen,
+				    migrate->new_master,
+				    migrate->master);
+
+	if (ret < 0)
+		kmem_cache_free(dlm_mle_cache, mle);
+
+	spin_unlock(&dlm->master_lock);
+unlock:
+	spin_unlock(&dlm->spinlock);
+
+	if (oldmle) {
+		/* master is known, detach if not already detached */
+		dlm_mle_detach_hb_events(dlm, oldmle);
+		dlm_put_mle(oldmle);
+	}
+
+	if (res)
+		dlm_lockres_put(res);
+leave:
+	dlm_put(dlm);
+	return ret;
+}
+
+/* must be holding dlm->spinlock and dlm->master_lock
+ * when adding a migration mle, we can clear any other mles
+ * in the master list because we know with certainty that
+ * the master is "master".  so we remove any old mle from
+ * the list after setting it's master field, and then add
+ * the new migration mle.  this way we can hold with the rule
+ * of having only one mle for a given lock name at all times. */
+static int dlm_add_migration_mle(struct dlm_ctxt *dlm,
+				 struct dlm_lock_resource *res,
+				 struct dlm_master_list_entry *mle,
+				 struct dlm_master_list_entry **oldmle,
+				 const char *name, unsigned int namelen,
+				 u8 new_master, u8 master)
+{
+	int found;
+	int ret = 0;
+
+	*oldmle = NULL;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&dlm->master_lock);
+
+	/* caller is responsible for any ref taken here on oldmle */
+	found = dlm_find_mle(dlm, oldmle, (char *)name, namelen);
+	if (found) {
+		struct dlm_master_list_entry *tmp = *oldmle;
+		spin_lock(&tmp->spinlock);
+		if (tmp->type == DLM_MLE_MIGRATION) {
+			if (master == dlm->node_num) {
+				/* ah another process raced me to it */
+				mlog(0, "tried to migrate %.*s, but some "
+				     "process beat me to it\n",
+				     namelen, name);
+				spin_unlock(&tmp->spinlock);
+				return -EEXIST;
+			} else {
+				/* bad.  2 NODES are trying to migrate! */
+				mlog(ML_ERROR, "migration error  mle: "
+				     "master=%u new_master=%u // request: "
+				     "master=%u new_master=%u // "
+				     "lockres=%.*s\n",
+				     tmp->master, tmp->new_master,
+				     master, new_master,
+				     namelen, name);
+				BUG();
+			}
+		} else {
+			/* this is essentially what assert_master does */
+			tmp->master = master;
+			atomic_set(&tmp->woken, 1);
+			wake_up(&tmp->wq);
+			/* remove it so that only one mle will be found */
+			__dlm_unlink_mle(dlm, tmp);
+			__dlm_mle_detach_hb_events(dlm, tmp);
+			if (tmp->type == DLM_MLE_MASTER) {
+				ret = DLM_MIGRATE_RESPONSE_MASTERY_REF;
+				mlog(0, "%s:%.*s: master=%u, newmaster=%u, "
+						"telling master to get ref "
+						"for cleared out mle during "
+						"migration\n", dlm->name,
+						namelen, name, master,
+						new_master);
+			}
+		}
+		spin_unlock(&tmp->spinlock);
+	}
+
+	/* now add a migration mle to the tail of the list */
+	dlm_init_mle(mle, DLM_MLE_MIGRATION, dlm, res, name, namelen);
+	mle->new_master = new_master;
+	/* the new master will be sending an assert master for this.
+	 * at that point we will get the refmap reference */
+	mle->master = master;
+	/* do this for consistency with other mle types */
+	set_bit(new_master, mle->maybe_map);
+	__dlm_insert_mle(dlm, mle);
+
+	return ret;
+}
+
+/*
+ * Sets the owner of the lockres, associated to the mle, to UNKNOWN
+ */
+static struct dlm_lock_resource *dlm_reset_mleres_owner(struct dlm_ctxt *dlm,
+					struct dlm_master_list_entry *mle)
+{
+	struct dlm_lock_resource *res;
+
+	/* Find the lockres associated to the mle and set its owner to UNK */
+	res = __dlm_lookup_lockres(dlm, mle->mname, mle->mnamelen,
+				   mle->mnamehash);
+	if (res) {
+		spin_unlock(&dlm->master_lock);
+
+		/* move lockres onto recovery list */
+		spin_lock(&res->spinlock);
+		dlm_set_lockres_owner(dlm, res, DLM_LOCK_RES_OWNER_UNKNOWN);
+		dlm_move_lockres_to_recovery_list(dlm, res);
+		spin_unlock(&res->spinlock);
+		dlm_lockres_put(res);
+
+		/* about to get rid of mle, detach from heartbeat */
+		__dlm_mle_detach_hb_events(dlm, mle);
+
+		/* dump the mle */
+		spin_lock(&dlm->master_lock);
+		__dlm_put_mle(mle);
+		spin_unlock(&dlm->master_lock);
+	}
+
+	return res;
+}
+
+static void dlm_clean_migration_mle(struct dlm_ctxt *dlm,
+				    struct dlm_master_list_entry *mle)
+{
+	__dlm_mle_detach_hb_events(dlm, mle);
+
+	spin_lock(&mle->spinlock);
+	__dlm_unlink_mle(dlm, mle);
+	atomic_set(&mle->woken, 1);
+	spin_unlock(&mle->spinlock);
+
+	wake_up(&mle->wq);
+}
+
+static void dlm_clean_block_mle(struct dlm_ctxt *dlm,
+				struct dlm_master_list_entry *mle, u8 dead_node)
+{
+	int bit;
+
+	BUG_ON(mle->type != DLM_MLE_BLOCK);
+
+	spin_lock(&mle->spinlock);
+	bit = find_first_bit(mle->maybe_map, O2NM_MAX_NODES);
+	if (bit != dead_node) {
+		mlog(0, "mle found, but dead node %u would not have been "
+		     "master\n", dead_node);
+		spin_unlock(&mle->spinlock);
+	} else {
+		/* Must drop the refcount by one since the assert_master will
+		 * never arrive. This may result in the mle being unlinked and
+		 * freed, but there may still be a process waiting in the
+		 * dlmlock path which is fine. */
+		mlog(0, "node %u was expected master\n", dead_node);
+		atomic_set(&mle->woken, 1);
+		spin_unlock(&mle->spinlock);
+		wake_up(&mle->wq);
+
+		/* Do not need events any longer, so detach from heartbeat */
+		__dlm_mle_detach_hb_events(dlm, mle);
+		__dlm_put_mle(mle);
+	}
+}
+
+void dlm_clean_master_list(struct dlm_ctxt *dlm, u8 dead_node)
+{
+	struct dlm_master_list_entry *mle;
+	struct dlm_lock_resource *res;
+	struct hlist_head *bucket;
+	struct hlist_node *tmp;
+	unsigned int i;
+
+	mlog(0, "dlm=%s, dead node=%u\n", dlm->name, dead_node);
+top:
+	assert_spin_locked(&dlm->spinlock);
+
+	/* clean the master list */
+	spin_lock(&dlm->master_lock);
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+		bucket = dlm_master_hash(dlm, i);
+		hlist_for_each_entry_safe(mle, tmp, bucket, master_hash_node) {
+			BUG_ON(mle->type != DLM_MLE_BLOCK &&
+			       mle->type != DLM_MLE_MASTER &&
+			       mle->type != DLM_MLE_MIGRATION);
+
+			/* MASTER mles are initiated locally. The waiting
+			 * process will notice the node map change shortly.
+			 * Let that happen as normal. */
+			if (mle->type == DLM_MLE_MASTER)
+				continue;
+
+			/* BLOCK mles are initiated by other nodes. Need to
+			 * clean up if the dead node would have been the
+			 * master. */
+			if (mle->type == DLM_MLE_BLOCK) {
+				dlm_clean_block_mle(dlm, mle, dead_node);
+				continue;
+			}
+
+			/* Everything else is a MIGRATION mle */
+
+			/* The rule for MIGRATION mles is that the master
+			 * becomes UNKNOWN if *either* the original or the new
+			 * master dies. All UNKNOWN lockres' are sent to
+			 * whichever node becomes the recovery master. The new
+			 * master is responsible for determining if there is
+			 * still a master for this lockres, or if he needs to
+			 * take over mastery. Either way, this node should
+			 * expect another message to resolve this. */
+
+			if (mle->master != dead_node &&
+			    mle->new_master != dead_node)
+				continue;
+
+			if (mle->new_master == dead_node && mle->inuse) {
+				mlog(ML_NOTICE, "%s: target %u died during "
+						"migration from %u, the MLE is "
+						"still keep used, ignore it!\n",
+						dlm->name, dead_node,
+						mle->master);
+				continue;
+			}
+
+			/* If we have reached this point, this mle needs to be
+			 * removed from the list and freed. */
+			dlm_clean_migration_mle(dlm, mle);
+
+			mlog(0, "%s: node %u died during migration from "
+			     "%u to %u!\n", dlm->name, dead_node, mle->master,
+			     mle->new_master);
+
+			/* If we find a lockres associated with the mle, we've
+			 * hit this rare case that messes up our lock ordering.
+			 * If so, we need to drop the master lock so that we can
+			 * take the lockres lock, meaning that we will have to
+			 * restart from the head of list. */
+			res = dlm_reset_mleres_owner(dlm, mle);
+			if (res)
+				/* restart */
+				goto top;
+
+			/* This may be the last reference */
+			__dlm_put_mle(mle);
+		}
+	}
+	spin_unlock(&dlm->master_lock);
+}
+
+int dlm_finish_migration(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			 u8 old_master)
+{
+	struct dlm_node_iter iter;
+	int ret = 0;
+
+	spin_lock(&dlm->spinlock);
+	dlm_node_iter_init(dlm->domain_map, &iter);
+	clear_bit(old_master, iter.node_map);
+	clear_bit(dlm->node_num, iter.node_map);
+	spin_unlock(&dlm->spinlock);
+
+	/* ownership of the lockres is changing.  account for the
+	 * mastery reference here since old_master will briefly have
+	 * a reference after the migration completes */
+	spin_lock(&res->spinlock);
+	dlm_lockres_set_refmap_bit(dlm, res, old_master);
+	spin_unlock(&res->spinlock);
+
+	mlog(0, "now time to do a migrate request to other nodes\n");
+	ret = dlm_do_migrate_request(dlm, res, old_master,
+				     dlm->node_num, &iter);
+	if (ret < 0) {
+		mlog_errno(ret);
+		goto leave;
+	}
+
+	mlog(0, "doing assert master of %.*s to all except the original node\n",
+	     res->lockname.len, res->lockname.name);
+	/* this call now finishes out the nodemap
+	 * even if one or more nodes die */
+	ret = dlm_do_assert_master(dlm, res, iter.node_map,
+				   DLM_ASSERT_MASTER_FINISH_MIGRATION);
+	if (ret < 0) {
+		/* no longer need to retry.  all living nodes contacted. */
+		mlog_errno(ret);
+		ret = 0;
+	}
+
+	memset(iter.node_map, 0, sizeof(iter.node_map));
+	set_bit(old_master, iter.node_map);
+	mlog(0, "doing assert master of %.*s back to %u\n",
+	     res->lockname.len, res->lockname.name, old_master);
+	ret = dlm_do_assert_master(dlm, res, iter.node_map,
+				   DLM_ASSERT_MASTER_FINISH_MIGRATION);
+	if (ret < 0) {
+		mlog(0, "assert master to original master failed "
+		     "with %d.\n", ret);
+		/* the only nonzero status here would be because of
+		 * a dead original node.  we're done. */
+		ret = 0;
+	}
+
+	/* all done, set the owner, clear the flag */
+	spin_lock(&res->spinlock);
+	dlm_set_lockres_owner(dlm, res, dlm->node_num);
+	res->state &= ~DLM_LOCK_RES_MIGRATING;
+	spin_unlock(&res->spinlock);
+	/* re-dirty it on the new master */
+	dlm_kick_thread(dlm, res);
+	wake_up(&res->wq);
+leave:
+	return ret;
+}
+
+/*
+ * LOCKRES AST REFCOUNT
+ * this is integral to migration
+ */
+
+/* for future intent to call an ast, reserve one ahead of time.
+ * this should be called only after waiting on the lockres
+ * with dlm_wait_on_lockres, and while still holding the
+ * spinlock after the call. */
+void __dlm_lockres_reserve_ast(struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_MIGRATING) {
+		__dlm_print_one_lock_resource(res);
+	}
+	BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
+
+	atomic_inc(&res->asts_reserved);
+}
+
+/*
+ * used to drop the reserved ast, either because it went unused,
+ * or because the ast/bast was actually called.
+ *
+ * also, if there is a pending migration on this lockres,
+ * and this was the last pending ast on the lockres,
+ * atomically set the MIGRATING flag before we drop the lock.
+ * this is how we ensure that migration can proceed with no
+ * asts in progress.  note that it is ok if the state of the
+ * queues is such that a lock should be granted in the future
+ * or that a bast should be fired, because the new master will
+ * shuffle the lists on this lockres as soon as it is migrated.
+ */
+void dlm_lockres_release_ast(struct dlm_ctxt *dlm,
+			     struct dlm_lock_resource *res)
+{
+	if (!atomic_dec_and_lock(&res->asts_reserved, &res->spinlock))
+		return;
+
+	if (!res->migration_pending) {
+		spin_unlock(&res->spinlock);
+		return;
+	}
+
+	BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
+	res->migration_pending = 0;
+	res->state |= DLM_LOCK_RES_MIGRATING;
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+	wake_up(&dlm->migration_wq);
+}
+
+void dlm_force_free_mles(struct dlm_ctxt *dlm)
+{
+	int i;
+	struct hlist_head *bucket;
+	struct dlm_master_list_entry *mle;
+	struct hlist_node *tmp;
+
+	/*
+	 * We notified all other nodes that we are exiting the domain and
+	 * marked the dlm state to DLM_CTXT_LEAVING. If any mles are still
+	 * around we force free them and wake any processes that are waiting
+	 * on the mles
+	 */
+	spin_lock(&dlm->spinlock);
+	spin_lock(&dlm->master_lock);
+
+	BUG_ON(dlm->dlm_state != DLM_CTXT_LEAVING);
+	BUG_ON((find_first_bit(dlm->domain_map, O2NM_MAX_NODES) < O2NM_MAX_NODES));
+
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+		bucket = dlm_master_hash(dlm, i);
+		hlist_for_each_entry_safe(mle, tmp, bucket, master_hash_node) {
+			if (mle->type != DLM_MLE_BLOCK) {
+				mlog(ML_ERROR, "bad mle: %p\n", mle);
+				dlm_print_one_mle(mle);
+			}
+			atomic_set(&mle->woken, 1);
+			wake_up(&mle->wq);
+
+			__dlm_unlink_mle(dlm, mle);
+			__dlm_mle_detach_hb_events(dlm, mle);
+			__dlm_put_mle(mle);
+		}
+	}
+	spin_unlock(&dlm->master_lock);
+	spin_unlock(&dlm->spinlock);
+}
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
new file mode 100644
index 000000000..52ad342fe
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -0,0 +1,2955 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmrecovery.c
+ *
+ * recovery stuff
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/timer.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_RECOVERY)
+#include "../cluster/masklog.h"
+
+static void dlm_do_local_recovery_cleanup(struct dlm_ctxt *dlm, u8 dead_node);
+
+static int dlm_recovery_thread(void *data);
+static int dlm_do_recovery(struct dlm_ctxt *dlm);
+
+static int dlm_pick_recovery_master(struct dlm_ctxt *dlm);
+static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8 dead_node);
+static int dlm_init_recovery_area(struct dlm_ctxt *dlm, u8 dead_node);
+static int dlm_request_all_locks(struct dlm_ctxt *dlm,
+				 u8 request_from, u8 dead_node);
+static void dlm_destroy_recovery_area(struct dlm_ctxt *dlm);
+
+static inline int dlm_num_locks_in_lockres(struct dlm_lock_resource *res);
+static void dlm_init_migratable_lockres(struct dlm_migratable_lockres *mres,
+					const char *lockname, int namelen,
+					int total_locks, u64 cookie,
+					u8 flags, u8 master);
+static int dlm_send_mig_lockres_msg(struct dlm_ctxt *dlm,
+				    struct dlm_migratable_lockres *mres,
+				    u8 send_to,
+				    struct dlm_lock_resource *res,
+				    int total_locks);
+static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     struct dlm_migratable_lockres *mres);
+static int dlm_send_finalize_reco_message(struct dlm_ctxt *dlm);
+static int dlm_send_all_done_msg(struct dlm_ctxt *dlm,
+				 u8 dead_node, u8 send_to);
+static int dlm_send_begin_reco_message(struct dlm_ctxt *dlm, u8 dead_node);
+static void dlm_move_reco_locks_to_list(struct dlm_ctxt *dlm,
+					struct list_head *list, u8 dead_node);
+static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
+					      u8 dead_node, u8 new_master);
+static void dlm_reco_ast(void *astdata);
+static void dlm_reco_bast(void *astdata, int blocked_type);
+static void dlm_reco_unlock_ast(void *astdata, enum dlm_status st);
+static void dlm_request_all_locks_worker(struct dlm_work_item *item,
+					 void *data);
+static void dlm_mig_lockres_worker(struct dlm_work_item *item, void *data);
+static int dlm_lockres_master_requery(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res,
+				      u8 *real_master);
+
+static u64 dlm_get_next_mig_cookie(void);
+
+static DEFINE_SPINLOCK(dlm_reco_state_lock);
+static DEFINE_SPINLOCK(dlm_mig_cookie_lock);
+static u64 dlm_mig_cookie = 1;
+
+static u64 dlm_get_next_mig_cookie(void)
+{
+	u64 c;
+	spin_lock(&dlm_mig_cookie_lock);
+	c = dlm_mig_cookie;
+	if (dlm_mig_cookie == (~0ULL))
+		dlm_mig_cookie = 1;
+	else
+		dlm_mig_cookie++;
+	spin_unlock(&dlm_mig_cookie_lock);
+	return c;
+}
+
+static inline void dlm_set_reco_dead_node(struct dlm_ctxt *dlm,
+					  u8 dead_node)
+{
+	assert_spin_locked(&dlm->spinlock);
+	if (dlm->reco.dead_node != dead_node)
+		mlog(0, "%s: changing dead_node from %u to %u\n",
+		     dlm->name, dlm->reco.dead_node, dead_node);
+	dlm->reco.dead_node = dead_node;
+}
+
+static inline void dlm_set_reco_master(struct dlm_ctxt *dlm,
+				       u8 master)
+{
+	assert_spin_locked(&dlm->spinlock);
+	mlog(0, "%s: changing new_master from %u to %u\n",
+	     dlm->name, dlm->reco.new_master, master);
+	dlm->reco.new_master = master;
+}
+
+static inline void __dlm_reset_recovery(struct dlm_ctxt *dlm)
+{
+	assert_spin_locked(&dlm->spinlock);
+	clear_bit(dlm->reco.dead_node, dlm->recovery_map);
+	dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
+	dlm_set_reco_master(dlm, O2NM_INVALID_NODE_NUM);
+}
+
+/* Worker function used during recovery. */
+void dlm_dispatch_work(struct work_struct *work)
+{
+	struct dlm_ctxt *dlm =
+		container_of(work, struct dlm_ctxt, dispatched_work);
+	LIST_HEAD(tmp_list);
+	struct dlm_work_item *item, *next;
+	dlm_workfunc_t *workfunc;
+	int tot=0;
+
+	spin_lock(&dlm->work_lock);
+	list_splice_init(&dlm->work_list, &tmp_list);
+	spin_unlock(&dlm->work_lock);
+
+	list_for_each_entry(item, &tmp_list, list) {
+		tot++;
+	}
+	mlog(0, "%s: work thread has %d work items\n", dlm->name, tot);
+
+	list_for_each_entry_safe(item, next, &tmp_list, list) {
+		workfunc = item->func;
+		list_del_init(&item->list);
+
+		/* already have ref on dlm to avoid having
+		 * it disappear.  just double-check. */
+		BUG_ON(item->dlm != dlm);
+
+		/* this is allowed to sleep and
+		 * call network stuff */
+		workfunc(item, item->data);
+
+		dlm_put(dlm);
+		kfree(item);
+	}
+}
+
+/*
+ * RECOVERY THREAD
+ */
+
+void dlm_kick_recovery_thread(struct dlm_ctxt *dlm)
+{
+	/* wake the recovery thread
+	 * this will wake the reco thread in one of three places
+	 * 1) sleeping with no recovery happening
+	 * 2) sleeping with recovery mastered elsewhere
+	 * 3) recovery mastered here, waiting on reco data */
+
+	wake_up(&dlm->dlm_reco_thread_wq);
+}
+
+/* Launch the recovery thread */
+int dlm_launch_recovery_thread(struct dlm_ctxt *dlm)
+{
+	mlog(0, "starting dlm recovery thread...\n");
+
+	dlm->dlm_reco_thread_task = kthread_run(dlm_recovery_thread, dlm,
+			"dlm_reco-%s", dlm->name);
+	if (IS_ERR(dlm->dlm_reco_thread_task)) {
+		mlog_errno(PTR_ERR(dlm->dlm_reco_thread_task));
+		dlm->dlm_reco_thread_task = NULL;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+void dlm_complete_recovery_thread(struct dlm_ctxt *dlm)
+{
+	if (dlm->dlm_reco_thread_task) {
+		mlog(0, "waiting for dlm recovery thread to exit\n");
+		kthread_stop(dlm->dlm_reco_thread_task);
+		dlm->dlm_reco_thread_task = NULL;
+	}
+}
+
+
+
+/*
+ * this is lame, but here's how recovery works...
+ * 1) all recovery threads cluster wide will work on recovering
+ *    ONE node at a time
+ * 2) negotiate who will take over all the locks for the dead node.
+ *    thats right... ALL the locks.
+ * 3) once a new master is chosen, everyone scans all locks
+ *    and moves aside those mastered by the dead guy
+ * 4) each of these locks should be locked until recovery is done
+ * 5) the new master collects up all of secondary lock queue info
+ *    one lock at a time, forcing each node to communicate back
+ *    before continuing
+ * 6) each secondary lock queue responds with the full known lock info
+ * 7) once the new master has run all its locks, it sends a ALLDONE!
+ *    message to everyone
+ * 8) upon receiving this message, the secondary queue node unlocks
+ *    and responds to the ALLDONE
+ * 9) once the new master gets responses from everyone, he unlocks
+ *    everything and recovery for this dead node is done
+ *10) go back to 2) while there are still dead nodes
+ *
+ */
+
+static void dlm_print_reco_node_status(struct dlm_ctxt *dlm)
+{
+	struct dlm_reco_node_data *ndata;
+	struct dlm_lock_resource *res;
+
+	mlog(ML_NOTICE, "%s(%d): recovery info, state=%s, dead=%u, master=%u\n",
+	     dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
+	     dlm->reco.state & DLM_RECO_STATE_ACTIVE ? "ACTIVE" : "inactive",
+	     dlm->reco.dead_node, dlm->reco.new_master);
+
+	list_for_each_entry(ndata, &dlm->reco.node_data, list) {
+		char *st = "unknown";
+		switch (ndata->state) {
+			case DLM_RECO_NODE_DATA_INIT:
+				st = "init";
+				break;
+			case DLM_RECO_NODE_DATA_REQUESTING:
+				st = "requesting";
+				break;
+			case DLM_RECO_NODE_DATA_DEAD:
+				st = "dead";
+				break;
+			case DLM_RECO_NODE_DATA_RECEIVING:
+				st = "receiving";
+				break;
+			case DLM_RECO_NODE_DATA_REQUESTED:
+				st = "requested";
+				break;
+			case DLM_RECO_NODE_DATA_DONE:
+				st = "done";
+				break;
+			case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+				st = "finalize-sent";
+				break;
+			default:
+				st = "bad";
+				break;
+		}
+		mlog(ML_NOTICE, "%s: reco state, node %u, state=%s\n",
+		     dlm->name, ndata->node_num, st);
+	}
+	list_for_each_entry(res, &dlm->reco.resources, recovering) {
+		mlog(ML_NOTICE, "%s: lockres %.*s on recovering list\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+	}
+}
+
+#define DLM_RECO_THREAD_TIMEOUT_MS (5 * 1000)
+
+static int dlm_recovery_thread(void *data)
+{
+	int status;
+	struct dlm_ctxt *dlm = data;
+	unsigned long timeout = msecs_to_jiffies(DLM_RECO_THREAD_TIMEOUT_MS);
+
+	mlog(0, "dlm thread running for %s...\n", dlm->name);
+
+	while (!kthread_should_stop()) {
+		if (dlm_domain_fully_joined(dlm)) {
+			status = dlm_do_recovery(dlm);
+			if (status == -EAGAIN) {
+				/* do not sleep, recheck immediately. */
+				continue;
+			}
+			if (status < 0)
+				mlog_errno(status);
+		}
+
+		wait_event_interruptible_timeout(dlm->dlm_reco_thread_wq,
+						 kthread_should_stop(),
+						 timeout);
+	}
+
+	mlog(0, "quitting DLM recovery thread\n");
+	return 0;
+}
+
+/* returns true when the recovery master has contacted us */
+static int dlm_reco_master_ready(struct dlm_ctxt *dlm)
+{
+	int ready;
+	spin_lock(&dlm->spinlock);
+	ready = (dlm->reco.new_master != O2NM_INVALID_NODE_NUM);
+	spin_unlock(&dlm->spinlock);
+	return ready;
+}
+
+/* returns true if node is no longer in the domain
+ * could be dead or just not joined */
+int dlm_is_node_dead(struct dlm_ctxt *dlm, u8 node)
+{
+	int dead;
+	spin_lock(&dlm->spinlock);
+	dead = !test_bit(node, dlm->domain_map);
+	spin_unlock(&dlm->spinlock);
+	return dead;
+}
+
+/* returns true if node is no longer in the domain
+ * could be dead or just not joined */
+static int dlm_is_node_recovered(struct dlm_ctxt *dlm, u8 node)
+{
+	int recovered;
+	spin_lock(&dlm->spinlock);
+	recovered = !test_bit(node, dlm->recovery_map);
+	spin_unlock(&dlm->spinlock);
+	return recovered;
+}
+
+
+void dlm_wait_for_node_death(struct dlm_ctxt *dlm, u8 node, int timeout)
+{
+	if (dlm_is_node_dead(dlm, node))
+		return;
+
+	printk(KERN_NOTICE "o2dlm: Waiting on the death of node %u in "
+	       "domain %s\n", node, dlm->name);
+
+	if (timeout)
+		wait_event_timeout(dlm->dlm_reco_thread_wq,
+				   dlm_is_node_dead(dlm, node),
+				   msecs_to_jiffies(timeout));
+	else
+		wait_event(dlm->dlm_reco_thread_wq,
+			   dlm_is_node_dead(dlm, node));
+}
+
+void dlm_wait_for_node_recovery(struct dlm_ctxt *dlm, u8 node, int timeout)
+{
+	if (dlm_is_node_recovered(dlm, node))
+		return;
+
+	printk(KERN_NOTICE "o2dlm: Waiting on the recovery of node %u in "
+	       "domain %s\n", node, dlm->name);
+
+	if (timeout)
+		wait_event_timeout(dlm->dlm_reco_thread_wq,
+				   dlm_is_node_recovered(dlm, node),
+				   msecs_to_jiffies(timeout));
+	else
+		wait_event(dlm->dlm_reco_thread_wq,
+			   dlm_is_node_recovered(dlm, node));
+}
+
+/* callers of the top-level api calls (dlmlock/dlmunlock) should
+ * block on the dlm->reco.event when recovery is in progress.
+ * the dlm recovery thread will set this state when it begins
+ * recovering a dead node (as the new master or not) and clear
+ * the state and wake as soon as all affected lock resources have
+ * been marked with the RECOVERY flag */
+static int dlm_in_recovery(struct dlm_ctxt *dlm)
+{
+	int in_recovery;
+	spin_lock(&dlm->spinlock);
+	in_recovery = !!(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
+	spin_unlock(&dlm->spinlock);
+	return in_recovery;
+}
+
+
+void dlm_wait_for_recovery(struct dlm_ctxt *dlm)
+{
+	if (dlm_in_recovery(dlm)) {
+		mlog(0, "%s: reco thread %d in recovery: "
+		     "state=%d, master=%u, dead=%u\n",
+		     dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
+		     dlm->reco.state, dlm->reco.new_master,
+		     dlm->reco.dead_node);
+	}
+	wait_event(dlm->reco.event, !dlm_in_recovery(dlm));
+}
+
+static void dlm_begin_recovery(struct dlm_ctxt *dlm)
+{
+	assert_spin_locked(&dlm->spinlock);
+	BUG_ON(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
+	printk(KERN_NOTICE "o2dlm: Begin recovery on domain %s for node %u\n",
+	       dlm->name, dlm->reco.dead_node);
+	dlm->reco.state |= DLM_RECO_STATE_ACTIVE;
+}
+
+static void dlm_end_recovery(struct dlm_ctxt *dlm)
+{
+	spin_lock(&dlm->spinlock);
+	BUG_ON(!(dlm->reco.state & DLM_RECO_STATE_ACTIVE));
+	dlm->reco.state &= ~DLM_RECO_STATE_ACTIVE;
+	spin_unlock(&dlm->spinlock);
+	printk(KERN_NOTICE "o2dlm: End recovery on domain %s\n", dlm->name);
+	wake_up(&dlm->reco.event);
+}
+
+static void dlm_print_recovery_master(struct dlm_ctxt *dlm)
+{
+	printk(KERN_NOTICE "o2dlm: Node %u (%s) is the Recovery Master for the "
+	       "dead node %u in domain %s\n", dlm->reco.new_master,
+	       (dlm->node_num == dlm->reco.new_master ? "me" : "he"),
+	       dlm->reco.dead_node, dlm->name);
+}
+
+static int dlm_do_recovery(struct dlm_ctxt *dlm)
+{
+	int status = 0;
+	int ret;
+
+	spin_lock(&dlm->spinlock);
+
+	if (dlm->migrate_done) {
+		mlog(0, "%s: no need do recovery after migrating all "
+		     "lock resources\n", dlm->name);
+		spin_unlock(&dlm->spinlock);
+		return 0;
+	}
+
+	/* check to see if the new master has died */
+	if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM &&
+	    test_bit(dlm->reco.new_master, dlm->recovery_map)) {
+		mlog(0, "new master %u died while recovering %u!\n",
+		     dlm->reco.new_master, dlm->reco.dead_node);
+		/* unset the new_master, leave dead_node */
+		dlm_set_reco_master(dlm, O2NM_INVALID_NODE_NUM);
+	}
+
+	/* select a target to recover */
+	if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
+		int bit;
+
+		bit = find_first_bit(dlm->recovery_map, O2NM_MAX_NODES);
+		if (bit >= O2NM_MAX_NODES || bit < 0)
+			dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
+		else
+			dlm_set_reco_dead_node(dlm, bit);
+	} else if (!test_bit(dlm->reco.dead_node, dlm->recovery_map)) {
+		/* BUG? */
+		mlog(ML_ERROR, "dead_node %u no longer in recovery map!\n",
+		     dlm->reco.dead_node);
+		dlm_set_reco_dead_node(dlm, O2NM_INVALID_NODE_NUM);
+	}
+
+	if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
+		// mlog(0, "nothing to recover!  sleeping now!\n");
+		spin_unlock(&dlm->spinlock);
+		/* return to main thread loop and sleep. */
+		return 0;
+	}
+	mlog(0, "%s(%d):recovery thread found node %u in the recovery map!\n",
+	     dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
+	     dlm->reco.dead_node);
+
+	/* take write barrier */
+	/* (stops the list reshuffling thread, proxy ast handling) */
+	dlm_begin_recovery(dlm);
+
+	spin_unlock(&dlm->spinlock);
+
+	if (dlm->reco.new_master == dlm->node_num)
+		goto master_here;
+
+	if (dlm->reco.new_master == O2NM_INVALID_NODE_NUM) {
+		/* choose a new master, returns 0 if this node
+		 * is the master, -EEXIST if it's another node.
+		 * this does not return until a new master is chosen
+		 * or recovery completes entirely. */
+		ret = dlm_pick_recovery_master(dlm);
+		if (!ret) {
+			/* already notified everyone.  go. */
+			goto master_here;
+		}
+		mlog(0, "another node will master this recovery session.\n");
+	}
+
+	dlm_print_recovery_master(dlm);
+
+	/* it is safe to start everything back up here
+	 * because all of the dead node's lock resources
+	 * have been marked as in-recovery */
+	dlm_end_recovery(dlm);
+
+	/* sleep out in main dlm_recovery_thread loop. */
+	return 0;
+
+master_here:
+	dlm_print_recovery_master(dlm);
+
+	status = dlm_remaster_locks(dlm, dlm->reco.dead_node);
+	if (status < 0) {
+		/* we should never hit this anymore */
+		mlog(ML_ERROR, "%s: Error %d remastering locks for node %u, "
+		     "retrying.\n", dlm->name, status, dlm->reco.dead_node);
+		/* yield a bit to allow any final network messages
+		 * to get handled on remaining nodes */
+		msleep(100);
+	} else {
+		/* success!  see if any other nodes need recovery */
+		mlog(0, "DONE mastering recovery of %s:%u here(this=%u)!\n",
+		     dlm->name, dlm->reco.dead_node, dlm->node_num);
+		spin_lock(&dlm->spinlock);
+		__dlm_reset_recovery(dlm);
+		dlm->reco.state &= ~DLM_RECO_STATE_FINALIZE;
+		spin_unlock(&dlm->spinlock);
+	}
+	dlm_end_recovery(dlm);
+
+	/* continue and look for another dead node */
+	return -EAGAIN;
+}
+
+static int dlm_remaster_locks(struct dlm_ctxt *dlm, u8 dead_node)
+{
+	int status = 0;
+	struct dlm_reco_node_data *ndata;
+	int all_nodes_done;
+	int destroy = 0;
+	int pass = 0;
+
+	do {
+		/* we have become recovery master.  there is no escaping
+		 * this, so just keep trying until we get it. */
+		status = dlm_init_recovery_area(dlm, dead_node);
+		if (status < 0) {
+			mlog(ML_ERROR, "%s: failed to alloc recovery area, "
+			     "retrying\n", dlm->name);
+			msleep(1000);
+		}
+	} while (status != 0);
+
+	/* safe to access the node data list without a lock, since this
+	 * process is the only one to change the list */
+	list_for_each_entry(ndata, &dlm->reco.node_data, list) {
+		BUG_ON(ndata->state != DLM_RECO_NODE_DATA_INIT);
+		ndata->state = DLM_RECO_NODE_DATA_REQUESTING;
+
+		mlog(0, "%s: Requesting lock info from node %u\n", dlm->name,
+		     ndata->node_num);
+
+		if (ndata->node_num == dlm->node_num) {
+			ndata->state = DLM_RECO_NODE_DATA_DONE;
+			continue;
+		}
+
+		do {
+			status = dlm_request_all_locks(dlm, ndata->node_num,
+						       dead_node);
+			if (status < 0) {
+				mlog_errno(status);
+				if (dlm_is_host_down(status)) {
+					/* node died, ignore it for recovery */
+					status = 0;
+					ndata->state = DLM_RECO_NODE_DATA_DEAD;
+					/* wait for the domain map to catch up
+					 * with the network state. */
+					wait_event_timeout(dlm->dlm_reco_thread_wq,
+							   dlm_is_node_dead(dlm,
+								ndata->node_num),
+							   msecs_to_jiffies(1000));
+					mlog(0, "waited 1 sec for %u, "
+					     "dead? %s\n", ndata->node_num,
+					     dlm_is_node_dead(dlm, ndata->node_num) ?
+					     "yes" : "no");
+				} else {
+					/* -ENOMEM on the other node */
+					mlog(0, "%s: node %u returned "
+					     "%d during recovery, retrying "
+					     "after a short wait\n",
+					     dlm->name, ndata->node_num,
+					     status);
+					msleep(100);
+				}
+			}
+		} while (status != 0);
+
+		spin_lock(&dlm_reco_state_lock);
+		switch (ndata->state) {
+			case DLM_RECO_NODE_DATA_INIT:
+			case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+			case DLM_RECO_NODE_DATA_REQUESTED:
+				BUG();
+				break;
+			case DLM_RECO_NODE_DATA_DEAD:
+				mlog(0, "node %u died after requesting "
+				     "recovery info for node %u\n",
+				     ndata->node_num, dead_node);
+				/* fine.  don't need this node's info.
+				 * continue without it. */
+				break;
+			case DLM_RECO_NODE_DATA_REQUESTING:
+				ndata->state = DLM_RECO_NODE_DATA_REQUESTED;
+				mlog(0, "now receiving recovery data from "
+				     "node %u for dead node %u\n",
+				     ndata->node_num, dead_node);
+				break;
+			case DLM_RECO_NODE_DATA_RECEIVING:
+				mlog(0, "already receiving recovery data from "
+				     "node %u for dead node %u\n",
+				     ndata->node_num, dead_node);
+				break;
+			case DLM_RECO_NODE_DATA_DONE:
+				mlog(0, "already DONE receiving recovery data "
+				     "from node %u for dead node %u\n",
+				     ndata->node_num, dead_node);
+				break;
+		}
+		spin_unlock(&dlm_reco_state_lock);
+	}
+
+	mlog(0, "%s: Done requesting all lock info\n", dlm->name);
+
+	/* nodes should be sending reco data now
+	 * just need to wait */
+
+	while (1) {
+		/* check all the nodes now to see if we are
+		 * done, or if anyone died */
+		all_nodes_done = 1;
+		spin_lock(&dlm_reco_state_lock);
+		list_for_each_entry(ndata, &dlm->reco.node_data, list) {
+			mlog(0, "checking recovery state of node %u\n",
+			     ndata->node_num);
+			switch (ndata->state) {
+				case DLM_RECO_NODE_DATA_INIT:
+				case DLM_RECO_NODE_DATA_REQUESTING:
+					mlog(ML_ERROR, "bad ndata state for "
+					     "node %u: state=%d\n",
+					     ndata->node_num, ndata->state);
+					BUG();
+					break;
+				case DLM_RECO_NODE_DATA_DEAD:
+					mlog(0, "node %u died after "
+					     "requesting recovery info for "
+					     "node %u\n", ndata->node_num,
+					     dead_node);
+					break;
+				case DLM_RECO_NODE_DATA_RECEIVING:
+				case DLM_RECO_NODE_DATA_REQUESTED:
+					mlog(0, "%s: node %u still in state %s\n",
+					     dlm->name, ndata->node_num,
+					     ndata->state==DLM_RECO_NODE_DATA_RECEIVING ?
+					     "receiving" : "requested");
+					all_nodes_done = 0;
+					break;
+				case DLM_RECO_NODE_DATA_DONE:
+					mlog(0, "%s: node %u state is done\n",
+					     dlm->name, ndata->node_num);
+					break;
+				case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+					mlog(0, "%s: node %u state is finalize\n",
+					     dlm->name, ndata->node_num);
+					break;
+			}
+		}
+		spin_unlock(&dlm_reco_state_lock);
+
+		mlog(0, "pass #%d, all_nodes_done?: %s\n", ++pass,
+		     all_nodes_done?"yes":"no");
+		if (all_nodes_done) {
+			int ret;
+
+			/* Set this flag on recovery master to avoid
+			 * a new recovery for another dead node start
+			 * before the recovery is not done. That may
+			 * cause recovery hung.*/
+			spin_lock(&dlm->spinlock);
+			dlm->reco.state |= DLM_RECO_STATE_FINALIZE;
+			spin_unlock(&dlm->spinlock);
+
+			/* all nodes are now in DLM_RECO_NODE_DATA_DONE state
+	 		 * just send a finalize message to everyone and
+	 		 * clean up */
+			mlog(0, "all nodes are done! send finalize\n");
+			ret = dlm_send_finalize_reco_message(dlm);
+			if (ret < 0)
+				mlog_errno(ret);
+
+			spin_lock(&dlm->spinlock);
+			dlm_finish_local_lockres_recovery(dlm, dead_node,
+							  dlm->node_num);
+			spin_unlock(&dlm->spinlock);
+			mlog(0, "should be done with recovery!\n");
+
+			mlog(0, "finishing recovery of %s at %lu, "
+			     "dead=%u, this=%u, new=%u\n", dlm->name,
+			     jiffies, dlm->reco.dead_node,
+			     dlm->node_num, dlm->reco.new_master);
+			destroy = 1;
+			status = 0;
+			/* rescan everything marked dirty along the way */
+			dlm_kick_thread(dlm, NULL);
+			break;
+		}
+		/* wait to be signalled, with periodic timeout
+		 * to check for node death */
+		wait_event_interruptible_timeout(dlm->dlm_reco_thread_wq,
+					 kthread_should_stop(),
+					 msecs_to_jiffies(DLM_RECO_THREAD_TIMEOUT_MS));
+
+	}
+
+	if (destroy)
+		dlm_destroy_recovery_area(dlm);
+
+	return status;
+}
+
+static int dlm_init_recovery_area(struct dlm_ctxt *dlm, u8 dead_node)
+{
+	int num=0;
+	struct dlm_reco_node_data *ndata;
+
+	spin_lock(&dlm->spinlock);
+	memcpy(dlm->reco.node_map, dlm->domain_map, sizeof(dlm->domain_map));
+	/* nodes can only be removed (by dying) after dropping
+	 * this lock, and death will be trapped later, so this should do */
+	spin_unlock(&dlm->spinlock);
+
+	while (1) {
+		num = find_next_bit (dlm->reco.node_map, O2NM_MAX_NODES, num);
+		if (num >= O2NM_MAX_NODES) {
+			break;
+		}
+		BUG_ON(num == dead_node);
+
+		ndata = kzalloc(sizeof(*ndata), GFP_NOFS);
+		if (!ndata) {
+			dlm_destroy_recovery_area(dlm);
+			return -ENOMEM;
+		}
+		ndata->node_num = num;
+		ndata->state = DLM_RECO_NODE_DATA_INIT;
+		spin_lock(&dlm_reco_state_lock);
+		list_add_tail(&ndata->list, &dlm->reco.node_data);
+		spin_unlock(&dlm_reco_state_lock);
+		num++;
+	}
+
+	return 0;
+}
+
+static void dlm_destroy_recovery_area(struct dlm_ctxt *dlm)
+{
+	struct dlm_reco_node_data *ndata, *next;
+	LIST_HEAD(tmplist);
+
+	spin_lock(&dlm_reco_state_lock);
+	list_splice_init(&dlm->reco.node_data, &tmplist);
+	spin_unlock(&dlm_reco_state_lock);
+
+	list_for_each_entry_safe(ndata, next, &tmplist, list) {
+		list_del_init(&ndata->list);
+		kfree(ndata);
+	}
+}
+
+static int dlm_request_all_locks(struct dlm_ctxt *dlm, u8 request_from,
+				 u8 dead_node)
+{
+	struct dlm_lock_request lr;
+	int ret;
+	int status;
+
+	mlog(0, "\n");
+
+
+	mlog(0, "dlm_request_all_locks: dead node is %u, sending request "
+		  "to %u\n", dead_node, request_from);
+
+	memset(&lr, 0, sizeof(lr));
+	lr.node_idx = dlm->node_num;
+	lr.dead_node = dead_node;
+
+	// send message
+	ret = o2net_send_message(DLM_LOCK_REQUEST_MSG, dlm->key,
+				 &lr, sizeof(lr), request_from, &status);
+
+	/* negative status is handled by caller */
+	if (ret < 0)
+		mlog(ML_ERROR, "%s: Error %d send LOCK_REQUEST to node %u "
+		     "to recover dead node %u\n", dlm->name, ret,
+		     request_from, dead_node);
+	else
+		ret = status;
+	// return from here, then
+	// sleep until all received or error
+	return ret;
+
+}
+
+int dlm_request_all_locks_handler(struct o2net_msg *msg, u32 len, void *data,
+				  void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_lock_request *lr = (struct dlm_lock_request *)msg->buf;
+	char *buf = NULL;
+	struct dlm_work_item *item = NULL;
+
+	if (!dlm_grab(dlm))
+		return -EINVAL;
+
+	if (lr->dead_node != dlm->reco.dead_node) {
+		mlog(ML_ERROR, "%s: node %u sent dead_node=%u, but local "
+		     "dead_node is %u\n", dlm->name, lr->node_idx,
+		     lr->dead_node, dlm->reco.dead_node);
+		dlm_print_reco_node_status(dlm);
+		/* this is a hack */
+		dlm_put(dlm);
+		return -ENOMEM;
+	}
+	BUG_ON(lr->dead_node != dlm->reco.dead_node);
+
+	item = kzalloc(sizeof(*item), GFP_NOFS);
+	if (!item) {
+		dlm_put(dlm);
+		return -ENOMEM;
+	}
+
+	/* this will get freed by dlm_request_all_locks_worker */
+	buf = (char *) __get_free_page(GFP_NOFS);
+	if (!buf) {
+		kfree(item);
+		dlm_put(dlm);
+		return -ENOMEM;
+	}
+
+	/* queue up work for dlm_request_all_locks_worker */
+	dlm_grab(dlm);  /* get an extra ref for the work item */
+	dlm_init_work_item(dlm, item, dlm_request_all_locks_worker, buf);
+	item->u.ral.reco_master = lr->node_idx;
+	item->u.ral.dead_node = lr->dead_node;
+	spin_lock(&dlm->work_lock);
+	list_add_tail(&item->list, &dlm->work_list);
+	spin_unlock(&dlm->work_lock);
+	queue_work(dlm->dlm_worker, &dlm->dispatched_work);
+
+	dlm_put(dlm);
+	return 0;
+}
+
+static void dlm_request_all_locks_worker(struct dlm_work_item *item, void *data)
+{
+	struct dlm_migratable_lockres *mres;
+	struct dlm_lock_resource *res;
+	struct dlm_ctxt *dlm;
+	LIST_HEAD(resources);
+	int ret;
+	u8 dead_node, reco_master;
+	int skip_all_done = 0;
+
+	dlm = item->dlm;
+	dead_node = item->u.ral.dead_node;
+	reco_master = item->u.ral.reco_master;
+	mres = (struct dlm_migratable_lockres *)data;
+
+	mlog(0, "%s: recovery worker started, dead=%u, master=%u\n",
+	     dlm->name, dead_node, reco_master);
+
+	if (dead_node != dlm->reco.dead_node ||
+	    reco_master != dlm->reco.new_master) {
+		/* worker could have been created before the recovery master
+		 * died.  if so, do not continue, but do not error. */
+		if (dlm->reco.new_master == O2NM_INVALID_NODE_NUM) {
+			mlog(ML_NOTICE, "%s: will not send recovery state, "
+			     "recovery master %u died, thread=(dead=%u,mas=%u)"
+			     " current=(dead=%u,mas=%u)\n", dlm->name,
+			     reco_master, dead_node, reco_master,
+			     dlm->reco.dead_node, dlm->reco.new_master);
+		} else {
+			mlog(ML_NOTICE, "%s: reco state invalid: reco(dead=%u, "
+			     "master=%u), request(dead=%u, master=%u)\n",
+			     dlm->name, dlm->reco.dead_node,
+			     dlm->reco.new_master, dead_node, reco_master);
+		}
+		goto leave;
+	}
+
+	/* lock resources should have already been moved to the
+ 	 * dlm->reco.resources list.  now move items from that list
+ 	 * to a temp list if the dead owner matches.  note that the
+	 * whole cluster recovers only one node at a time, so we
+	 * can safely move UNKNOWN lock resources for each recovery
+	 * session. */
+	dlm_move_reco_locks_to_list(dlm, &resources, dead_node);
+
+	/* now we can begin blasting lockreses without the dlm lock */
+
+	/* any errors returned will be due to the new_master dying,
+	 * the dlm_reco_thread should detect this */
+	list_for_each_entry(res, &resources, recovering) {
+		ret = dlm_send_one_lockres(dlm, res, mres, reco_master,
+				   	DLM_MRES_RECOVERY);
+		if (ret < 0) {
+			mlog(ML_ERROR, "%s: node %u went down while sending "
+			     "recovery state for dead node %u, ret=%d\n", dlm->name,
+			     reco_master, dead_node, ret);
+			skip_all_done = 1;
+			break;
+		}
+	}
+
+	/* move the resources back to the list */
+	spin_lock(&dlm->spinlock);
+	list_splice_init(&resources, &dlm->reco.resources);
+	spin_unlock(&dlm->spinlock);
+
+	if (!skip_all_done) {
+		ret = dlm_send_all_done_msg(dlm, dead_node, reco_master);
+		if (ret < 0) {
+			mlog(ML_ERROR, "%s: node %u went down while sending "
+			     "recovery all-done for dead node %u, ret=%d\n",
+			     dlm->name, reco_master, dead_node, ret);
+		}
+	}
+leave:
+	free_page((unsigned long)data);
+}
+
+
+static int dlm_send_all_done_msg(struct dlm_ctxt *dlm, u8 dead_node, u8 send_to)
+{
+	int ret, tmpret;
+	struct dlm_reco_data_done done_msg;
+
+	memset(&done_msg, 0, sizeof(done_msg));
+	done_msg.node_idx = dlm->node_num;
+	done_msg.dead_node = dead_node;
+	mlog(0, "sending DATA DONE message to %u, "
+	     "my node=%u, dead node=%u\n", send_to, done_msg.node_idx,
+	     done_msg.dead_node);
+
+	ret = o2net_send_message(DLM_RECO_DATA_DONE_MSG, dlm->key, &done_msg,
+				 sizeof(done_msg), send_to, &tmpret);
+	if (ret < 0) {
+		mlog(ML_ERROR, "%s: Error %d send RECO_DATA_DONE to node %u "
+		     "to recover dead node %u\n", dlm->name, ret, send_to,
+		     dead_node);
+		if (!dlm_is_host_down(ret)) {
+			BUG();
+		}
+	} else
+		ret = tmpret;
+	return ret;
+}
+
+
+int dlm_reco_data_done_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_reco_data_done *done = (struct dlm_reco_data_done *)msg->buf;
+	struct dlm_reco_node_data *ndata = NULL;
+	int ret = -EINVAL;
+
+	if (!dlm_grab(dlm))
+		return -EINVAL;
+
+	mlog(0, "got DATA DONE: dead_node=%u, reco.dead_node=%u, "
+	     "node_idx=%u, this node=%u\n", done->dead_node,
+	     dlm->reco.dead_node, done->node_idx, dlm->node_num);
+
+	mlog_bug_on_msg((done->dead_node != dlm->reco.dead_node),
+			"Got DATA DONE: dead_node=%u, reco.dead_node=%u, "
+			"node_idx=%u, this node=%u\n", done->dead_node,
+			dlm->reco.dead_node, done->node_idx, dlm->node_num);
+
+	spin_lock(&dlm_reco_state_lock);
+	list_for_each_entry(ndata, &dlm->reco.node_data, list) {
+		if (ndata->node_num != done->node_idx)
+			continue;
+
+		switch (ndata->state) {
+			/* should have moved beyond INIT but not to FINALIZE yet */
+			case DLM_RECO_NODE_DATA_INIT:
+			case DLM_RECO_NODE_DATA_DEAD:
+			case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+				mlog(ML_ERROR, "bad ndata state for node %u:"
+				     " state=%d\n", ndata->node_num,
+				     ndata->state);
+				BUG();
+				break;
+			/* these states are possible at this point, anywhere along
+			 * the line of recovery */
+			case DLM_RECO_NODE_DATA_DONE:
+			case DLM_RECO_NODE_DATA_RECEIVING:
+			case DLM_RECO_NODE_DATA_REQUESTED:
+			case DLM_RECO_NODE_DATA_REQUESTING:
+				mlog(0, "node %u is DONE sending "
+					  "recovery data!\n",
+					  ndata->node_num);
+
+				ndata->state = DLM_RECO_NODE_DATA_DONE;
+				ret = 0;
+				break;
+		}
+	}
+	spin_unlock(&dlm_reco_state_lock);
+
+	/* wake the recovery thread, some node is done */
+	if (!ret)
+		dlm_kick_recovery_thread(dlm);
+
+	if (ret < 0)
+		mlog(ML_ERROR, "failed to find recovery node data for node "
+		     "%u\n", done->node_idx);
+	dlm_put(dlm);
+
+	mlog(0, "leaving reco data done handler, ret=%d\n", ret);
+	return ret;
+}
+
+static void dlm_move_reco_locks_to_list(struct dlm_ctxt *dlm,
+					struct list_head *list,
+				       	u8 dead_node)
+{
+	struct dlm_lock_resource *res, *next;
+	struct dlm_lock *lock;
+
+	spin_lock(&dlm->spinlock);
+	list_for_each_entry_safe(res, next, &dlm->reco.resources, recovering) {
+		/* always prune any $RECOVERY entries for dead nodes,
+		 * otherwise hangs can occur during later recovery */
+		if (dlm_is_recovery_lock(res->lockname.name,
+					 res->lockname.len)) {
+			spin_lock(&res->spinlock);
+			list_for_each_entry(lock, &res->granted, list) {
+				if (lock->ml.node == dead_node) {
+					mlog(0, "AHA! there was "
+					     "a $RECOVERY lock for dead "
+					     "node %u (%s)!\n",
+					     dead_node, dlm->name);
+					list_del_init(&lock->list);
+					dlm_lock_put(lock);
+					/* Can't schedule DLM_UNLOCK_FREE_LOCK
+					 * - do manually */
+					dlm_lock_put(lock);
+					break;
+				}
+			}
+			spin_unlock(&res->spinlock);
+			continue;
+		}
+
+		if (res->owner == dead_node) {
+			mlog(0, "found lockres owned by dead node while "
+				  "doing recovery for node %u. sending it.\n",
+				  dead_node);
+			list_move_tail(&res->recovering, list);
+		} else if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
+			mlog(0, "found UNKNOWN owner while doing recovery "
+				  "for node %u. sending it.\n", dead_node);
+			list_move_tail(&res->recovering, list);
+		}
+	}
+	spin_unlock(&dlm->spinlock);
+}
+
+static inline int dlm_num_locks_in_lockres(struct dlm_lock_resource *res)
+{
+	int total_locks = 0;
+	struct list_head *iter, *queue = &res->granted;
+	int i;
+
+	for (i=0; i<3; i++) {
+		list_for_each(iter, queue)
+			total_locks++;
+		queue++;
+	}
+	return total_locks;
+}
+
+
+static int dlm_send_mig_lockres_msg(struct dlm_ctxt *dlm,
+				      struct dlm_migratable_lockres *mres,
+				      u8 send_to,
+				      struct dlm_lock_resource *res,
+				      int total_locks)
+{
+	u64 mig_cookie = be64_to_cpu(mres->mig_cookie);
+	int mres_total_locks = be32_to_cpu(mres->total_locks);
+	int ret = 0, status = 0;
+	u8 orig_flags = mres->flags,
+	   orig_master = mres->master;
+
+	BUG_ON(mres->num_locks > DLM_MAX_MIGRATABLE_LOCKS);
+	if (!mres->num_locks)
+		return 0;
+
+	/* add an all-done flag if we reached the last lock */
+	orig_flags = mres->flags;
+	BUG_ON(total_locks > mres_total_locks);
+	if (total_locks == mres_total_locks)
+		mres->flags |= DLM_MRES_ALL_DONE;
+
+	mlog(0, "%s:%.*s: sending mig lockres (%s) to %u\n",
+	     dlm->name, res->lockname.len, res->lockname.name,
+	     orig_flags & DLM_MRES_MIGRATION ? "migration" : "recovery",
+	     send_to);
+
+	/* send it */
+	ret = o2net_send_message(DLM_MIG_LOCKRES_MSG, dlm->key, mres,
+				 struct_size(mres, ml, mres->num_locks),
+				 send_to, &status);
+	if (ret < 0) {
+		/* XXX: negative status is not handled.
+		 * this will end up killing this node. */
+		mlog(ML_ERROR, "%s: res %.*s, Error %d send MIG_LOCKRES to "
+		     "node %u (%s)\n", dlm->name, mres->lockname_len,
+		     mres->lockname, ret, send_to,
+		     (orig_flags & DLM_MRES_MIGRATION ?
+		      "migration" : "recovery"));
+	} else {
+		/* might get an -ENOMEM back here */
+		ret = status;
+		if (ret < 0) {
+			mlog_errno(ret);
+
+			if (ret == -EFAULT) {
+				mlog(ML_ERROR, "node %u told me to kill "
+				     "myself!\n", send_to);
+				BUG();
+			}
+		}
+	}
+
+	/* zero and reinit the message buffer */
+	dlm_init_migratable_lockres(mres, res->lockname.name,
+				    res->lockname.len, mres_total_locks,
+				    mig_cookie, orig_flags, orig_master);
+	return ret;
+}
+
+static void dlm_init_migratable_lockres(struct dlm_migratable_lockres *mres,
+					const char *lockname, int namelen,
+					int total_locks, u64 cookie,
+					u8 flags, u8 master)
+{
+	/* mres here is one full page */
+	clear_page(mres);
+	mres->lockname_len = namelen;
+	memcpy(mres->lockname, lockname, namelen);
+	mres->num_locks = 0;
+	mres->total_locks = cpu_to_be32(total_locks);
+	mres->mig_cookie = cpu_to_be64(cookie);
+	mres->flags = flags;
+	mres->master = master;
+}
+
+static void dlm_prepare_lvb_for_migration(struct dlm_lock *lock,
+					  struct dlm_migratable_lockres *mres,
+					  int queue)
+{
+	if (!lock->lksb)
+	       return;
+
+	/* Ignore lvb in all locks in the blocked list */
+	if (queue == DLM_BLOCKED_LIST)
+		return;
+
+	/* Only consider lvbs in locks with granted EX or PR lock levels */
+	if (lock->ml.type != LKM_EXMODE && lock->ml.type != LKM_PRMODE)
+		return;
+
+	if (dlm_lvb_is_empty(mres->lvb)) {
+		memcpy(mres->lvb, lock->lksb->lvb, DLM_LVB_LEN);
+		return;
+	}
+
+	/* Ensure the lvb copied for migration matches in other valid locks */
+	if (!memcmp(mres->lvb, lock->lksb->lvb, DLM_LVB_LEN))
+		return;
+
+	mlog(ML_ERROR, "Mismatched lvb in lock cookie=%u:%llu, name=%.*s, "
+	     "node=%u\n",
+	     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+	     lock->lockres->lockname.len, lock->lockres->lockname.name,
+	     lock->ml.node);
+	dlm_print_one_lock_resource(lock->lockres);
+	BUG();
+}
+
+/* returns 1 if this lock fills the network structure,
+ * 0 otherwise */
+static int dlm_add_lock_to_array(struct dlm_lock *lock,
+				 struct dlm_migratable_lockres *mres, int queue)
+{
+	struct dlm_migratable_lock *ml;
+	int lock_num = mres->num_locks;
+
+	ml = &(mres->ml[lock_num]);
+	ml->cookie = lock->ml.cookie;
+	ml->type = lock->ml.type;
+	ml->convert_type = lock->ml.convert_type;
+	ml->highest_blocked = lock->ml.highest_blocked;
+	ml->list = queue;
+	if (lock->lksb) {
+		ml->flags = lock->lksb->flags;
+		dlm_prepare_lvb_for_migration(lock, mres, queue);
+	}
+	ml->node = lock->ml.node;
+	mres->num_locks++;
+	/* we reached the max, send this network message */
+	if (mres->num_locks == DLM_MAX_MIGRATABLE_LOCKS)
+		return 1;
+	return 0;
+}
+
+static void dlm_add_dummy_lock(struct dlm_ctxt *dlm,
+			       struct dlm_migratable_lockres *mres)
+{
+	struct dlm_lock dummy;
+	memset(&dummy, 0, sizeof(dummy));
+	dummy.ml.cookie = 0;
+	dummy.ml.type = LKM_IVMODE;
+	dummy.ml.convert_type = LKM_IVMODE;
+	dummy.ml.highest_blocked = LKM_IVMODE;
+	dummy.lksb = NULL;
+	dummy.ml.node = dlm->node_num;
+	dlm_add_lock_to_array(&dummy, mres, DLM_BLOCKED_LIST);
+}
+
+static inline int dlm_is_dummy_lock(struct dlm_ctxt *dlm,
+				    struct dlm_migratable_lock *ml,
+				    u8 *nodenum)
+{
+	if (unlikely(ml->cookie == 0 &&
+	    ml->type == LKM_IVMODE &&
+	    ml->convert_type == LKM_IVMODE &&
+	    ml->highest_blocked == LKM_IVMODE &&
+	    ml->list == DLM_BLOCKED_LIST)) {
+		*nodenum = ml->node;
+		return 1;
+	}
+	return 0;
+}
+
+int dlm_send_one_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			 struct dlm_migratable_lockres *mres,
+			 u8 send_to, u8 flags)
+{
+	struct list_head *queue;
+	int total_locks, i;
+	u64 mig_cookie = 0;
+	struct dlm_lock *lock;
+	int ret = 0;
+
+	BUG_ON(!(flags & (DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));
+
+	mlog(0, "sending to %u\n", send_to);
+
+	total_locks = dlm_num_locks_in_lockres(res);
+	if (total_locks > DLM_MAX_MIGRATABLE_LOCKS) {
+		/* rare, but possible */
+		mlog(0, "argh.  lockres has %d locks.  this will "
+			  "require more than one network packet to "
+			  "migrate\n", total_locks);
+		mig_cookie = dlm_get_next_mig_cookie();
+	}
+
+	dlm_init_migratable_lockres(mres, res->lockname.name,
+				    res->lockname.len, total_locks,
+				    mig_cookie, flags, res->owner);
+
+	total_locks = 0;
+	for (i=DLM_GRANTED_LIST; i<=DLM_BLOCKED_LIST; i++) {
+		queue = dlm_list_idx_to_ptr(res, i);
+		list_for_each_entry(lock, queue, list) {
+			/* add another lock. */
+			total_locks++;
+			if (!dlm_add_lock_to_array(lock, mres, i))
+				continue;
+
+			/* this filled the lock message,
+			 * we must send it immediately. */
+			ret = dlm_send_mig_lockres_msg(dlm, mres, send_to,
+						       res, total_locks);
+			if (ret < 0)
+				goto error;
+		}
+	}
+	if (total_locks == 0) {
+		/* send a dummy lock to indicate a mastery reference only */
+		mlog(0, "%s:%.*s: sending dummy lock to %u, %s\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     send_to, flags & DLM_MRES_RECOVERY ? "recovery" :
+		     "migration");
+		dlm_add_dummy_lock(dlm, mres);
+	}
+	/* flush any remaining locks */
+	ret = dlm_send_mig_lockres_msg(dlm, mres, send_to, res, total_locks);
+	if (ret < 0)
+		goto error;
+	return ret;
+
+error:
+	mlog(ML_ERROR, "%s: dlm_send_mig_lockres_msg returned %d\n",
+	     dlm->name, ret);
+	if (!dlm_is_host_down(ret))
+		BUG();
+	mlog(0, "%s: node %u went down while sending %s "
+	     "lockres %.*s\n", dlm->name, send_to,
+	     flags & DLM_MRES_RECOVERY ?  "recovery" : "migration",
+	     res->lockname.len, res->lockname.name);
+	return ret;
+}
+
+
+
+/*
+ * this message will contain no more than one page worth of
+ * recovery data, and it will work on only one lockres.
+ * there may be many locks in this page, and we may need to wait
+ * for additional packets to complete all the locks (rare, but
+ * possible).
+ */
+/*
+ * NOTE: the allocation error cases here are scary
+ * we really cannot afford to fail an alloc in recovery
+ * do we spin?  returning an error only delays the problem really
+ */
+
+int dlm_mig_lockres_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_migratable_lockres *mres =
+		(struct dlm_migratable_lockres *)msg->buf;
+	int ret = 0;
+	u8 real_master;
+	u8 extra_refs = 0;
+	char *buf = NULL;
+	struct dlm_work_item *item = NULL;
+	struct dlm_lock_resource *res = NULL;
+	unsigned int hash;
+
+	if (!dlm_grab(dlm))
+		return -EINVAL;
+
+	if (!dlm_joined(dlm)) {
+		mlog(ML_ERROR, "Domain %s not joined! "
+			  "lockres %.*s, master %u\n",
+			  dlm->name, mres->lockname_len,
+			  mres->lockname, mres->master);
+		dlm_put(dlm);
+		return -EINVAL;
+	}
+
+	BUG_ON(!(mres->flags & (DLM_MRES_RECOVERY|DLM_MRES_MIGRATION)));
+
+	real_master = mres->master;
+	if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
+		/* cannot migrate a lockres with no master */
+		BUG_ON(!(mres->flags & DLM_MRES_RECOVERY));
+	}
+
+	mlog(0, "%s message received from node %u\n",
+		  (mres->flags & DLM_MRES_RECOVERY) ?
+		  "recovery" : "migration", mres->master);
+	if (mres->flags & DLM_MRES_ALL_DONE)
+		mlog(0, "all done flag.  all lockres data received!\n");
+
+	ret = -ENOMEM;
+	buf = kmalloc(be16_to_cpu(msg->data_len), GFP_NOFS);
+	item = kzalloc(sizeof(*item), GFP_NOFS);
+	if (!buf || !item)
+		goto leave;
+
+	/* lookup the lock to see if we have a secondary queue for this
+	 * already...  just add the locks in and this will have its owner
+	 * and RECOVERY flag changed when it completes. */
+	hash = dlm_lockid_hash(mres->lockname, mres->lockname_len);
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres_full(dlm, mres->lockname, mres->lockname_len,
+			hash);
+	if (res) {
+	 	/* this will get a ref on res */
+		/* mark it as recovering/migrating and hash it */
+		spin_lock(&res->spinlock);
+		if (res->state & DLM_LOCK_RES_DROPPING_REF) {
+			mlog(0, "%s: node is attempting to migrate "
+				"lockres %.*s, but marked as dropping "
+				" ref!\n", dlm->name,
+				mres->lockname_len, mres->lockname);
+			ret = -EINVAL;
+			spin_unlock(&res->spinlock);
+			spin_unlock(&dlm->spinlock);
+			dlm_lockres_put(res);
+			goto leave;
+		}
+
+		if (mres->flags & DLM_MRES_RECOVERY) {
+			res->state |= DLM_LOCK_RES_RECOVERING;
+		} else {
+			if (res->state & DLM_LOCK_RES_MIGRATING) {
+				/* this is at least the second
+				 * lockres message */
+				mlog(0, "lock %.*s is already migrating\n",
+					  mres->lockname_len,
+					  mres->lockname);
+			} else if (res->state & DLM_LOCK_RES_RECOVERING) {
+				/* caller should BUG */
+				mlog(ML_ERROR, "node is attempting to migrate "
+				     "lock %.*s, but marked as recovering!\n",
+				     mres->lockname_len, mres->lockname);
+				ret = -EFAULT;
+				spin_unlock(&res->spinlock);
+				spin_unlock(&dlm->spinlock);
+				dlm_lockres_put(res);
+				goto leave;
+			}
+			res->state |= DLM_LOCK_RES_MIGRATING;
+		}
+		spin_unlock(&res->spinlock);
+		spin_unlock(&dlm->spinlock);
+	} else {
+		spin_unlock(&dlm->spinlock);
+		/* need to allocate, just like if it was
+		 * mastered here normally  */
+		res = dlm_new_lockres(dlm, mres->lockname, mres->lockname_len);
+		if (!res)
+			goto leave;
+
+		/* to match the ref that we would have gotten if
+		 * dlm_lookup_lockres had succeeded */
+		dlm_lockres_get(res);
+
+		/* mark it as recovering/migrating and hash it */
+		if (mres->flags & DLM_MRES_RECOVERY)
+			res->state |= DLM_LOCK_RES_RECOVERING;
+		else
+			res->state |= DLM_LOCK_RES_MIGRATING;
+
+		spin_lock(&dlm->spinlock);
+		__dlm_insert_lockres(dlm, res);
+		spin_unlock(&dlm->spinlock);
+
+		/* Add an extra ref for this lock-less lockres lest the
+		 * dlm_thread purges it before we get the chance to add
+		 * locks to it */
+		dlm_lockres_get(res);
+
+		/* There are three refs that need to be put.
+		 * 1. Taken above.
+		 * 2. kref_init in dlm_new_lockres()->dlm_init_lockres().
+		 * 3. dlm_lookup_lockres()
+		 * The first one is handled at the end of this function. The
+		 * other two are handled in the worker thread after locks have
+		 * been attached. Yes, we don't wait for purge time to match
+		 * kref_init. The lockres will still have atleast one ref
+		 * added because it is in the hash __dlm_insert_lockres() */
+		extra_refs++;
+
+		/* now that the new lockres is inserted,
+		 * make it usable by other processes */
+		spin_lock(&res->spinlock);
+		res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+		spin_unlock(&res->spinlock);
+		wake_up(&res->wq);
+	}
+
+	/* at this point we have allocated everything we need,
+	 * and we have a hashed lockres with an extra ref and
+	 * the proper res->state flags. */
+	ret = 0;
+	spin_lock(&res->spinlock);
+	/* drop this either when master requery finds a different master
+	 * or when a lock is added by the recovery worker */
+	dlm_lockres_grab_inflight_ref(dlm, res);
+	if (mres->master == DLM_LOCK_RES_OWNER_UNKNOWN) {
+		/* migration cannot have an unknown master */
+		BUG_ON(!(mres->flags & DLM_MRES_RECOVERY));
+		mlog(0, "recovery has passed me a lockres with an "
+			  "unknown owner.. will need to requery: "
+			  "%.*s\n", mres->lockname_len, mres->lockname);
+	} else {
+		/* take a reference now to pin the lockres, drop it
+		 * when locks are added in the worker */
+		dlm_change_lockres_owner(dlm, res, dlm->node_num);
+	}
+	spin_unlock(&res->spinlock);
+
+	/* queue up work for dlm_mig_lockres_worker */
+	dlm_grab(dlm);  /* get an extra ref for the work item */
+	memcpy(buf, msg->buf, be16_to_cpu(msg->data_len));  /* copy the whole message */
+	dlm_init_work_item(dlm, item, dlm_mig_lockres_worker, buf);
+	item->u.ml.lockres = res; /* already have a ref */
+	item->u.ml.real_master = real_master;
+	item->u.ml.extra_ref = extra_refs;
+	spin_lock(&dlm->work_lock);
+	list_add_tail(&item->list, &dlm->work_list);
+	spin_unlock(&dlm->work_lock);
+	queue_work(dlm->dlm_worker, &dlm->dispatched_work);
+
+leave:
+	/* One extra ref taken needs to be put here */
+	if (extra_refs)
+		dlm_lockres_put(res);
+
+	dlm_put(dlm);
+	if (ret < 0) {
+		kfree(buf);
+		kfree(item);
+		mlog_errno(ret);
+	}
+
+	return ret;
+}
+
+
+static void dlm_mig_lockres_worker(struct dlm_work_item *item, void *data)
+{
+	struct dlm_ctxt *dlm;
+	struct dlm_migratable_lockres *mres;
+	int ret = 0;
+	struct dlm_lock_resource *res;
+	u8 real_master;
+	u8 extra_ref;
+
+	dlm = item->dlm;
+	mres = (struct dlm_migratable_lockres *)data;
+
+	res = item->u.ml.lockres;
+	real_master = item->u.ml.real_master;
+	extra_ref = item->u.ml.extra_ref;
+
+	if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
+		/* this case is super-rare. only occurs if
+		 * node death happens during migration. */
+again:
+		ret = dlm_lockres_master_requery(dlm, res, &real_master);
+		if (ret < 0) {
+			mlog(0, "dlm_lockres_master_requery ret=%d\n",
+				  ret);
+			goto again;
+		}
+		if (real_master == DLM_LOCK_RES_OWNER_UNKNOWN) {
+			mlog(0, "lockres %.*s not claimed.  "
+				   "this node will take it.\n",
+				   res->lockname.len, res->lockname.name);
+		} else {
+			spin_lock(&res->spinlock);
+			dlm_lockres_drop_inflight_ref(dlm, res);
+			spin_unlock(&res->spinlock);
+			mlog(0, "master needs to respond to sender "
+				  "that node %u still owns %.*s\n",
+				  real_master, res->lockname.len,
+				  res->lockname.name);
+			/* cannot touch this lockres */
+			goto leave;
+		}
+	}
+
+	ret = dlm_process_recovery_data(dlm, res, mres);
+	if (ret < 0)
+		mlog(0, "dlm_process_recovery_data returned  %d\n", ret);
+	else
+		mlog(0, "dlm_process_recovery_data succeeded\n");
+
+	if ((mres->flags & (DLM_MRES_MIGRATION|DLM_MRES_ALL_DONE)) ==
+	                   (DLM_MRES_MIGRATION|DLM_MRES_ALL_DONE)) {
+		ret = dlm_finish_migration(dlm, res, mres->master);
+		if (ret < 0)
+			mlog_errno(ret);
+	}
+
+leave:
+	/* See comment in dlm_mig_lockres_handler() */
+	if (res) {
+		if (extra_ref)
+			dlm_lockres_put(res);
+		dlm_lockres_put(res);
+	}
+	kfree(data);
+}
+
+
+
+static int dlm_lockres_master_requery(struct dlm_ctxt *dlm,
+				      struct dlm_lock_resource *res,
+				      u8 *real_master)
+{
+	struct dlm_node_iter iter;
+	int nodenum;
+	int ret = 0;
+
+	*real_master = DLM_LOCK_RES_OWNER_UNKNOWN;
+
+	/* we only reach here if one of the two nodes in a
+	 * migration died while the migration was in progress.
+	 * at this point we need to requery the master.  we
+	 * know that the new_master got as far as creating
+	 * an mle on at least one node, but we do not know
+	 * if any nodes had actually cleared the mle and set
+	 * the master to the new_master.  the old master
+	 * is supposed to set the owner to UNKNOWN in the
+	 * event of a new_master death, so the only possible
+	 * responses that we can get from nodes here are
+	 * that the master is new_master, or that the master
+	 * is UNKNOWN.
+	 * if all nodes come back with UNKNOWN then we know
+	 * the lock needs remastering here.
+	 * if any node comes back with a valid master, check
+	 * to see if that master is the one that we are
+	 * recovering.  if so, then the new_master died and
+	 * we need to remaster this lock.  if not, then the
+	 * new_master survived and that node will respond to
+	 * other nodes about the owner.
+	 * if there is an owner, this node needs to dump this
+	 * lockres and alert the sender that this lockres
+	 * was rejected. */
+	spin_lock(&dlm->spinlock);
+	dlm_node_iter_init(dlm->domain_map, &iter);
+	spin_unlock(&dlm->spinlock);
+
+	while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
+		/* do not send to self */
+		if (nodenum == dlm->node_num)
+			continue;
+		ret = dlm_do_master_requery(dlm, res, nodenum, real_master);
+		if (ret < 0) {
+			mlog_errno(ret);
+			if (!dlm_is_host_down(ret))
+				BUG();
+			/* host is down, so answer for that node would be
+			 * DLM_LOCK_RES_OWNER_UNKNOWN.  continue. */
+		}
+		if (*real_master != DLM_LOCK_RES_OWNER_UNKNOWN) {
+			mlog(0, "lock master is %u\n", *real_master);
+			break;
+		}
+	}
+	return ret;
+}
+
+
+int dlm_do_master_requery(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
+			  u8 nodenum, u8 *real_master)
+{
+	int ret;
+	struct dlm_master_requery req;
+	int status = DLM_LOCK_RES_OWNER_UNKNOWN;
+
+	memset(&req, 0, sizeof(req));
+	req.node_idx = dlm->node_num;
+	req.namelen = res->lockname.len;
+	memcpy(req.name, res->lockname.name, res->lockname.len);
+
+resend:
+	ret = o2net_send_message(DLM_MASTER_REQUERY_MSG, dlm->key,
+				 &req, sizeof(req), nodenum, &status);
+	if (ret < 0)
+		mlog(ML_ERROR, "Error %d when sending message %u (key "
+		     "0x%x) to node %u\n", ret, DLM_MASTER_REQUERY_MSG,
+		     dlm->key, nodenum);
+	else if (status == -ENOMEM) {
+		mlog_errno(status);
+		msleep(50);
+		goto resend;
+	} else {
+		BUG_ON(status < 0);
+		BUG_ON(status > DLM_LOCK_RES_OWNER_UNKNOWN);
+		*real_master = (u8) (status & 0xff);
+		mlog(0, "node %u responded to master requery with %u\n",
+			  nodenum, *real_master);
+		ret = 0;
+	}
+	return ret;
+}
+
+
+/* this function cannot error, so unless the sending
+ * or receiving of the message failed, the owner can
+ * be trusted */
+int dlm_master_requery_handler(struct o2net_msg *msg, u32 len, void *data,
+			       void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_master_requery *req = (struct dlm_master_requery *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	unsigned int hash;
+	int master = DLM_LOCK_RES_OWNER_UNKNOWN;
+	u32 flags = DLM_ASSERT_MASTER_REQUERY;
+	int dispatched = 0;
+
+	if (!dlm_grab(dlm)) {
+		/* since the domain has gone away on this
+		 * node, the proper response is UNKNOWN */
+		return master;
+	}
+
+	hash = dlm_lockid_hash(req->name, req->namelen);
+
+	spin_lock(&dlm->spinlock);
+	res = __dlm_lookup_lockres(dlm, req->name, req->namelen, hash);
+	if (res) {
+		spin_lock(&res->spinlock);
+		master = res->owner;
+		if (master == dlm->node_num) {
+			int ret = dlm_dispatch_assert_master(dlm, res,
+							     0, 0, flags);
+			if (ret < 0) {
+				mlog_errno(ret);
+				spin_unlock(&res->spinlock);
+				dlm_lockres_put(res);
+				spin_unlock(&dlm->spinlock);
+				dlm_put(dlm);
+				/* sender will take care of this and retry */
+				return ret;
+			} else {
+				dispatched = 1;
+				__dlm_lockres_grab_inflight_worker(dlm, res);
+				spin_unlock(&res->spinlock);
+			}
+		} else {
+			/* put.. incase we are not the master */
+			spin_unlock(&res->spinlock);
+			dlm_lockres_put(res);
+		}
+	}
+	spin_unlock(&dlm->spinlock);
+
+	if (!dispatched)
+		dlm_put(dlm);
+	return master;
+}
+
+static inline struct list_head *
+dlm_list_num_to_pointer(struct dlm_lock_resource *res, int list_num)
+{
+	struct list_head *ret;
+	BUG_ON(list_num < 0);
+	BUG_ON(list_num > 2);
+	ret = &(res->granted);
+	ret += list_num;
+	return ret;
+}
+/* TODO: do ast flush business
+ * TODO: do MIGRATING and RECOVERING spinning
+ */
+
+/*
+* NOTE about in-flight requests during migration:
+*
+* Before attempting the migrate, the master has marked the lockres as
+* MIGRATING and then flushed all of its pending ASTS.  So any in-flight
+* requests either got queued before the MIGRATING flag got set, in which
+* case the lock data will reflect the change and a return message is on
+* the way, or the request failed to get in before MIGRATING got set.  In
+* this case, the caller will be told to spin and wait for the MIGRATING
+* flag to be dropped, then recheck the master.
+* This holds true for the convert, cancel and unlock cases, and since lvb
+* updates are tied to these same messages, it applies to lvb updates as
+* well.  For the lock case, there is no way a lock can be on the master
+* queue and not be on the secondary queue since the lock is always added
+* locally first.  This means that the new target node will never be sent
+* a lock that he doesn't already have on the list.
+* In total, this means that the local lock is correct and should not be
+* updated to match the one sent by the master.  Any messages sent back
+* from the master before the MIGRATING flag will bring the lock properly
+* up-to-date, and the change will be ordered properly for the waiter.
+* We will *not* attempt to modify the lock underneath the waiter.
+*/
+
+static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
+				     struct dlm_lock_resource *res,
+				     struct dlm_migratable_lockres *mres)
+{
+	struct dlm_migratable_lock *ml;
+	struct list_head *queue, *iter;
+	struct list_head *tmpq = NULL;
+	struct dlm_lock *newlock = NULL;
+	struct dlm_lockstatus *lksb = NULL;
+	int ret = 0;
+	int i, j, bad;
+	struct dlm_lock *lock;
+	u8 from = O2NM_MAX_NODES;
+	__be64 c;
+
+	mlog(0, "running %d locks for this lockres\n", mres->num_locks);
+	for (i=0; i<mres->num_locks; i++) {
+		ml = &(mres->ml[i]);
+
+		if (dlm_is_dummy_lock(dlm, ml, &from)) {
+			/* placeholder, just need to set the refmap bit */
+			BUG_ON(mres->num_locks != 1);
+			mlog(0, "%s:%.*s: dummy lock for %u\n",
+			     dlm->name, mres->lockname_len, mres->lockname,
+			     from);
+			spin_lock(&res->spinlock);
+			dlm_lockres_set_refmap_bit(dlm, res, from);
+			spin_unlock(&res->spinlock);
+			break;
+		}
+		BUG_ON(ml->highest_blocked != LKM_IVMODE);
+		newlock = NULL;
+		lksb = NULL;
+
+		queue = dlm_list_num_to_pointer(res, ml->list);
+		tmpq = NULL;
+
+		/* if the lock is for the local node it needs to
+		 * be moved to the proper location within the queue.
+		 * do not allocate a new lock structure. */
+		if (ml->node == dlm->node_num) {
+			/* MIGRATION ONLY! */
+			BUG_ON(!(mres->flags & DLM_MRES_MIGRATION));
+
+			lock = NULL;
+			spin_lock(&res->spinlock);
+			for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
+				tmpq = dlm_list_idx_to_ptr(res, j);
+				list_for_each(iter, tmpq) {
+					lock = list_entry(iter,
+						  struct dlm_lock, list);
+					if (lock->ml.cookie == ml->cookie)
+						break;
+					lock = NULL;
+				}
+				if (lock)
+					break;
+			}
+
+			/* lock is always created locally first, and
+			 * destroyed locally last.  it must be on the list */
+			if (!lock) {
+				c = ml->cookie;
+				mlog(ML_ERROR, "Could not find local lock "
+					       "with cookie %u:%llu, node %u, "
+					       "list %u, flags 0x%x, type %d, "
+					       "conv %d, highest blocked %d\n",
+				     dlm_get_lock_cookie_node(be64_to_cpu(c)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(c)),
+				     ml->node, ml->list, ml->flags, ml->type,
+				     ml->convert_type, ml->highest_blocked);
+				__dlm_print_one_lock_resource(res);
+				BUG();
+			}
+
+			if (lock->ml.node != ml->node) {
+				c = lock->ml.cookie;
+				mlog(ML_ERROR, "Mismatched node# in lock "
+				     "cookie %u:%llu, name %.*s, node %u\n",
+				     dlm_get_lock_cookie_node(be64_to_cpu(c)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(c)),
+				     res->lockname.len, res->lockname.name,
+				     lock->ml.node);
+				c = ml->cookie;
+				mlog(ML_ERROR, "Migrate lock cookie %u:%llu, "
+				     "node %u, list %u, flags 0x%x, type %d, "
+				     "conv %d, highest blocked %d\n",
+				     dlm_get_lock_cookie_node(be64_to_cpu(c)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(c)),
+				     ml->node, ml->list, ml->flags, ml->type,
+				     ml->convert_type, ml->highest_blocked);
+				__dlm_print_one_lock_resource(res);
+				BUG();
+			}
+
+			if (tmpq != queue) {
+				c = ml->cookie;
+				mlog(0, "Lock cookie %u:%llu was on list %u "
+				     "instead of list %u for %.*s\n",
+				     dlm_get_lock_cookie_node(be64_to_cpu(c)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(c)),
+				     j, ml->list, res->lockname.len,
+				     res->lockname.name);
+				__dlm_print_one_lock_resource(res);
+				spin_unlock(&res->spinlock);
+				continue;
+			}
+
+			/* see NOTE above about why we do not update
+			 * to match the master here */
+
+			/* move the lock to its proper place */
+			/* do not alter lock refcount.  switching lists. */
+			list_move_tail(&lock->list, queue);
+			spin_unlock(&res->spinlock);
+
+			mlog(0, "just reordered a local lock!\n");
+			continue;
+		}
+
+		/* lock is for another node. */
+		newlock = dlm_new_lock(ml->type, ml->node,
+				       be64_to_cpu(ml->cookie), NULL);
+		if (!newlock) {
+			ret = -ENOMEM;
+			goto leave;
+		}
+		lksb = newlock->lksb;
+		dlm_lock_attach_lockres(newlock, res);
+
+		if (ml->convert_type != LKM_IVMODE) {
+			BUG_ON(queue != &res->converting);
+			newlock->ml.convert_type = ml->convert_type;
+		}
+		lksb->flags |= (ml->flags &
+				(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB));
+
+		if (ml->type == LKM_NLMODE)
+			goto skip_lvb;
+
+		/*
+		 * If the lock is in the blocked list it can't have a valid lvb,
+		 * so skip it
+		 */
+		if (ml->list == DLM_BLOCKED_LIST)
+			goto skip_lvb;
+
+		if (!dlm_lvb_is_empty(mres->lvb)) {
+			if (lksb->flags & DLM_LKSB_PUT_LVB) {
+				/* other node was trying to update
+				 * lvb when node died.  recreate the
+				 * lksb with the updated lvb. */
+				memcpy(lksb->lvb, mres->lvb, DLM_LVB_LEN);
+				/* the lock resource lvb update must happen
+				 * NOW, before the spinlock is dropped.
+				 * we no longer wait for the AST to update
+				 * the lvb. */
+				memcpy(res->lvb, mres->lvb, DLM_LVB_LEN);
+			} else {
+				/* otherwise, the node is sending its
+				 * most recent valid lvb info */
+				BUG_ON(ml->type != LKM_EXMODE &&
+				       ml->type != LKM_PRMODE);
+				if (!dlm_lvb_is_empty(res->lvb) &&
+ 				    (ml->type == LKM_EXMODE ||
+ 				     memcmp(res->lvb, mres->lvb, DLM_LVB_LEN))) {
+ 					int i;
+ 					mlog(ML_ERROR, "%s:%.*s: received bad "
+ 					     "lvb! type=%d\n", dlm->name,
+ 					     res->lockname.len,
+ 					     res->lockname.name, ml->type);
+ 					printk("lockres lvb=[");
+ 					for (i=0; i<DLM_LVB_LEN; i++)
+ 						printk("%02x", res->lvb[i]);
+ 					printk("]\nmigrated lvb=[");
+ 					for (i=0; i<DLM_LVB_LEN; i++)
+ 						printk("%02x", mres->lvb[i]);
+ 					printk("]\n");
+ 					dlm_print_one_lock_resource(res);
+ 					BUG();
+				}
+				memcpy(res->lvb, mres->lvb, DLM_LVB_LEN);
+			}
+		}
+skip_lvb:
+
+		/* NOTE:
+		 * wrt lock queue ordering and recovery:
+		 *    1. order of locks on granted queue is
+		 *       meaningless.
+		 *    2. order of locks on converting queue is
+		 *       LOST with the node death.  sorry charlie.
+		 *    3. order of locks on the blocked queue is
+		 *       also LOST.
+		 * order of locks does not affect integrity, it
+		 * just means that a lock request may get pushed
+		 * back in line as a result of the node death.
+		 * also note that for a given node the lock order
+		 * for its secondary queue locks is preserved
+		 * relative to each other, but clearly *not*
+		 * preserved relative to locks from other nodes.
+		 */
+		bad = 0;
+		spin_lock(&res->spinlock);
+		list_for_each_entry(lock, queue, list) {
+			if (lock->ml.cookie == ml->cookie) {
+				c = lock->ml.cookie;
+				mlog(ML_ERROR, "%s:%.*s: %u:%llu: lock already "
+				     "exists on this lockres!\n", dlm->name,
+				     res->lockname.len, res->lockname.name,
+				     dlm_get_lock_cookie_node(be64_to_cpu(c)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(c)));
+
+				mlog(ML_NOTICE, "sent lock: type=%d, conv=%d, "
+				     "node=%u, cookie=%u:%llu, queue=%d\n",
+	      			     ml->type, ml->convert_type, ml->node,
+				     dlm_get_lock_cookie_node(be64_to_cpu(ml->cookie)),
+				     dlm_get_lock_cookie_seq(be64_to_cpu(ml->cookie)),
+				     ml->list);
+
+				__dlm_print_one_lock_resource(res);
+				bad = 1;
+				break;
+			}
+		}
+		if (!bad) {
+			dlm_lock_get(newlock);
+			if (mres->flags & DLM_MRES_RECOVERY &&
+					ml->list == DLM_CONVERTING_LIST &&
+					newlock->ml.type >
+					newlock->ml.convert_type) {
+				/* newlock is doing downconvert, add it to the
+				 * head of converting list */
+				list_add(&newlock->list, queue);
+			} else
+				list_add_tail(&newlock->list, queue);
+			mlog(0, "%s:%.*s: added lock for node %u, "
+			     "setting refmap bit\n", dlm->name,
+			     res->lockname.len, res->lockname.name, ml->node);
+			dlm_lockres_set_refmap_bit(dlm, res, ml->node);
+		}
+		spin_unlock(&res->spinlock);
+	}
+	mlog(0, "done running all the locks\n");
+
+leave:
+	/* balance the ref taken when the work was queued */
+	spin_lock(&res->spinlock);
+	dlm_lockres_drop_inflight_ref(dlm, res);
+	spin_unlock(&res->spinlock);
+
+	if (ret < 0)
+		mlog_errno(ret);
+
+	return ret;
+}
+
+void dlm_move_lockres_to_recovery_list(struct dlm_ctxt *dlm,
+				       struct dlm_lock_resource *res)
+{
+	int i;
+	struct list_head *queue;
+	struct dlm_lock *lock, *next;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+	res->state |= DLM_LOCK_RES_RECOVERING;
+	if (!list_empty(&res->recovering)) {
+		mlog(0,
+		     "Recovering res %s:%.*s, is already on recovery list!\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		list_del_init(&res->recovering);
+		dlm_lockres_put(res);
+	}
+	/* We need to hold a reference while on the recovery list */
+	dlm_lockres_get(res);
+	list_add_tail(&res->recovering, &dlm->reco.resources);
+
+	/* find any pending locks and put them back on proper list */
+	for (i=DLM_BLOCKED_LIST; i>=DLM_GRANTED_LIST; i--) {
+		queue = dlm_list_idx_to_ptr(res, i);
+		list_for_each_entry_safe(lock, next, queue, list) {
+			dlm_lock_get(lock);
+			if (lock->convert_pending) {
+				/* move converting lock back to granted */
+				mlog(0, "node died with convert pending "
+				     "on %.*s. move back to granted list.\n",
+				     res->lockname.len, res->lockname.name);
+				dlm_revert_pending_convert(res, lock);
+				lock->convert_pending = 0;
+			} else if (lock->lock_pending) {
+				/* remove pending lock requests completely */
+				BUG_ON(i != DLM_BLOCKED_LIST);
+				mlog(0, "node died with lock pending "
+				     "on %.*s. remove from blocked list and skip.\n",
+				     res->lockname.len, res->lockname.name);
+				/* lock will be floating until ref in
+				 * dlmlock_remote is freed after the network
+				 * call returns.  ok for it to not be on any
+				 * list since no ast can be called
+				 * (the master is dead). */
+				dlm_revert_pending_lock(res, lock);
+				lock->lock_pending = 0;
+			} else if (lock->unlock_pending) {
+				/* if an unlock was in progress, treat as
+				 * if this had completed successfully
+				 * before sending this lock state to the
+				 * new master.  note that the dlm_unlock
+				 * call is still responsible for calling
+				 * the unlockast.  that will happen after
+				 * the network call times out.  for now,
+				 * just move lists to prepare the new
+				 * recovery master.  */
+				BUG_ON(i != DLM_GRANTED_LIST);
+				mlog(0, "node died with unlock pending "
+				     "on %.*s. remove from blocked list and skip.\n",
+				     res->lockname.len, res->lockname.name);
+				dlm_commit_pending_unlock(res, lock);
+				lock->unlock_pending = 0;
+			} else if (lock->cancel_pending) {
+				/* if a cancel was in progress, treat as
+				 * if this had completed successfully
+				 * before sending this lock state to the
+				 * new master */
+				BUG_ON(i != DLM_CONVERTING_LIST);
+				mlog(0, "node died with cancel pending "
+				     "on %.*s. move back to granted list.\n",
+				     res->lockname.len, res->lockname.name);
+				dlm_commit_pending_cancel(res, lock);
+				lock->cancel_pending = 0;
+			}
+			dlm_lock_put(lock);
+		}
+	}
+}
+
+
+
+/* removes all recovered locks from the recovery list.
+ * sets the res->owner to the new master.
+ * unsets the RECOVERY flag and wakes waiters. */
+static void dlm_finish_local_lockres_recovery(struct dlm_ctxt *dlm,
+					      u8 dead_node, u8 new_master)
+{
+	int i;
+	struct hlist_head *bucket;
+	struct dlm_lock_resource *res, *next;
+
+	assert_spin_locked(&dlm->spinlock);
+
+	list_for_each_entry_safe(res, next, &dlm->reco.resources, recovering) {
+		if (res->owner == dead_node) {
+			mlog(0, "%s: res %.*s, Changing owner from %u to %u\n",
+			     dlm->name, res->lockname.len, res->lockname.name,
+			     res->owner, new_master);
+			list_del_init(&res->recovering);
+			spin_lock(&res->spinlock);
+			/* new_master has our reference from
+			 * the lock state sent during recovery */
+			dlm_change_lockres_owner(dlm, res, new_master);
+			res->state &= ~DLM_LOCK_RES_RECOVERING;
+			if (__dlm_lockres_has_locks(res))
+				__dlm_dirty_lockres(dlm, res);
+			spin_unlock(&res->spinlock);
+			wake_up(&res->wq);
+			dlm_lockres_put(res);
+		}
+	}
+
+	/* this will become unnecessary eventually, but
+	 * for now we need to run the whole hash, clear
+	 * the RECOVERING state and set the owner
+	 * if necessary */
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+		bucket = dlm_lockres_hash(dlm, i);
+		hlist_for_each_entry(res, bucket, hash_node) {
+			if (res->state & DLM_LOCK_RES_RECOVERY_WAITING) {
+				spin_lock(&res->spinlock);
+				res->state &= ~DLM_LOCK_RES_RECOVERY_WAITING;
+				spin_unlock(&res->spinlock);
+				wake_up(&res->wq);
+			}
+
+			if (!(res->state & DLM_LOCK_RES_RECOVERING))
+				continue;
+
+			if (res->owner != dead_node &&
+			    res->owner != dlm->node_num)
+				continue;
+
+			if (!list_empty(&res->recovering)) {
+				list_del_init(&res->recovering);
+				dlm_lockres_put(res);
+			}
+
+			/* new_master has our reference from
+			 * the lock state sent during recovery */
+			mlog(0, "%s: res %.*s, Changing owner from %u to %u\n",
+			     dlm->name, res->lockname.len, res->lockname.name,
+			     res->owner, new_master);
+			spin_lock(&res->spinlock);
+			dlm_change_lockres_owner(dlm, res, new_master);
+			res->state &= ~DLM_LOCK_RES_RECOVERING;
+			if (__dlm_lockres_has_locks(res))
+				__dlm_dirty_lockres(dlm, res);
+			spin_unlock(&res->spinlock);
+			wake_up(&res->wq);
+		}
+	}
+}
+
+static inline int dlm_lvb_needs_invalidation(struct dlm_lock *lock, int local)
+{
+	if (local) {
+		if (lock->ml.type != LKM_EXMODE &&
+		    lock->ml.type != LKM_PRMODE)
+			return 1;
+	} else if (lock->ml.type == LKM_EXMODE)
+		return 1;
+	return 0;
+}
+
+static void dlm_revalidate_lvb(struct dlm_ctxt *dlm,
+			       struct dlm_lock_resource *res, u8 dead_node)
+{
+	struct list_head *queue;
+	struct dlm_lock *lock;
+	int blank_lvb = 0, local = 0;
+	int i;
+	u8 search_node;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	if (res->owner == dlm->node_num)
+		/* if this node owned the lockres, and if the dead node
+		 * had an EX when he died, blank out the lvb */
+		search_node = dead_node;
+	else {
+		/* if this is a secondary lockres, and we had no EX or PR
+		 * locks granted, we can no longer trust the lvb */
+		search_node = dlm->node_num;
+		local = 1;  /* check local state for valid lvb */
+	}
+
+	for (i=DLM_GRANTED_LIST; i<=DLM_CONVERTING_LIST; i++) {
+		queue = dlm_list_idx_to_ptr(res, i);
+		list_for_each_entry(lock, queue, list) {
+			if (lock->ml.node == search_node) {
+				if (dlm_lvb_needs_invalidation(lock, local)) {
+					/* zero the lksb lvb and lockres lvb */
+					blank_lvb = 1;
+					memset(lock->lksb->lvb, 0, DLM_LVB_LEN);
+				}
+			}
+		}
+	}
+
+	if (blank_lvb) {
+		mlog(0, "clearing %.*s lvb, dead node %u had EX\n",
+		     res->lockname.len, res->lockname.name, dead_node);
+		memset(res->lvb, 0, DLM_LVB_LEN);
+	}
+}
+
+static void dlm_free_dead_locks(struct dlm_ctxt *dlm,
+				struct dlm_lock_resource *res, u8 dead_node)
+{
+	struct dlm_lock *lock, *next;
+	unsigned int freed = 0;
+
+	/* this node is the lockres master:
+	 * 1) remove any stale locks for the dead node
+	 * 2) if the dead node had an EX when he died, blank out the lvb
+	 */
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	/* We do two dlm_lock_put(). One for removing from list and the other is
+	 * to force the DLM_UNLOCK_FREE_LOCK action so as to free the locks */
+
+	/* TODO: check pending_asts, pending_basts here */
+	list_for_each_entry_safe(lock, next, &res->granted, list) {
+		if (lock->ml.node == dead_node) {
+			list_del_init(&lock->list);
+			dlm_lock_put(lock);
+			/* Can't schedule DLM_UNLOCK_FREE_LOCK - do manually */
+			dlm_lock_put(lock);
+			freed++;
+		}
+	}
+	list_for_each_entry_safe(lock, next, &res->converting, list) {
+		if (lock->ml.node == dead_node) {
+			list_del_init(&lock->list);
+			dlm_lock_put(lock);
+			/* Can't schedule DLM_UNLOCK_FREE_LOCK - do manually */
+			dlm_lock_put(lock);
+			freed++;
+		}
+	}
+	list_for_each_entry_safe(lock, next, &res->blocked, list) {
+		if (lock->ml.node == dead_node) {
+			list_del_init(&lock->list);
+			dlm_lock_put(lock);
+			/* Can't schedule DLM_UNLOCK_FREE_LOCK - do manually */
+			dlm_lock_put(lock);
+			freed++;
+		}
+	}
+
+	if (freed) {
+		mlog(0, "%s:%.*s: freed %u locks for dead node %u, "
+		     "dropping ref from lockres\n", dlm->name,
+		     res->lockname.len, res->lockname.name, freed, dead_node);
+		if(!test_bit(dead_node, res->refmap)) {
+			mlog(ML_ERROR, "%s:%.*s: freed %u locks for dead node %u, "
+			     "but ref was not set\n", dlm->name,
+			     res->lockname.len, res->lockname.name, freed, dead_node);
+			__dlm_print_one_lock_resource(res);
+		}
+		res->state |= DLM_LOCK_RES_RECOVERY_WAITING;
+		dlm_lockres_clear_refmap_bit(dlm, res, dead_node);
+	} else if (test_bit(dead_node, res->refmap)) {
+		mlog(0, "%s:%.*s: dead node %u had a ref, but had "
+		     "no locks and had not purged before dying\n", dlm->name,
+		     res->lockname.len, res->lockname.name, dead_node);
+		dlm_lockres_clear_refmap_bit(dlm, res, dead_node);
+	}
+
+	/* do not kick thread yet */
+	__dlm_dirty_lockres(dlm, res);
+}
+
+static void dlm_do_local_recovery_cleanup(struct dlm_ctxt *dlm, u8 dead_node)
+{
+	struct dlm_lock_resource *res;
+	int i;
+	struct hlist_head *bucket;
+	struct hlist_node *tmp;
+	struct dlm_lock *lock;
+
+
+	/* purge any stale mles */
+	dlm_clean_master_list(dlm, dead_node);
+
+	/*
+	 * now clean up all lock resources.  there are two rules:
+	 *
+	 * 1) if the dead node was the master, move the lockres
+	 *    to the recovering list.  set the RECOVERING flag.
+	 *    this lockres needs to be cleaned up before it can
+	 *    be used further.
+	 *
+	 * 2) if this node was the master, remove all locks from
+	 *    each of the lockres queues that were owned by the
+	 *    dead node.  once recovery finishes, the dlm thread
+	 *    can be kicked again to see if any ASTs or BASTs
+	 *    need to be fired as a result.
+	 */
+	for (i = 0; i < DLM_HASH_BUCKETS; i++) {
+		bucket = dlm_lockres_hash(dlm, i);
+		hlist_for_each_entry_safe(res, tmp, bucket, hash_node) {
+ 			/* always prune any $RECOVERY entries for dead nodes,
+ 			 * otherwise hangs can occur during later recovery */
+			if (dlm_is_recovery_lock(res->lockname.name,
+						 res->lockname.len)) {
+				spin_lock(&res->spinlock);
+				list_for_each_entry(lock, &res->granted, list) {
+					if (lock->ml.node == dead_node) {
+						mlog(0, "AHA! there was "
+						     "a $RECOVERY lock for dead "
+						     "node %u (%s)!\n",
+						     dead_node, dlm->name);
+						list_del_init(&lock->list);
+						dlm_lock_put(lock);
+						/* Can't schedule
+						 * DLM_UNLOCK_FREE_LOCK
+						 * - do manually */
+						dlm_lock_put(lock);
+						break;
+					}
+				}
+
+				if ((res->owner == dead_node) &&
+							(res->state & DLM_LOCK_RES_DROPPING_REF)) {
+					dlm_lockres_get(res);
+					__dlm_do_purge_lockres(dlm, res);
+					spin_unlock(&res->spinlock);
+					wake_up(&res->wq);
+					dlm_lockres_put(res);
+					continue;
+				} else if (res->owner == dlm->node_num)
+					dlm_lockres_clear_refmap_bit(dlm, res, dead_node);
+				spin_unlock(&res->spinlock);
+				continue;
+			}
+			spin_lock(&res->spinlock);
+			/* zero the lvb if necessary */
+			dlm_revalidate_lvb(dlm, res, dead_node);
+			if (res->owner == dead_node) {
+				if (res->state & DLM_LOCK_RES_DROPPING_REF) {
+					mlog(0, "%s:%.*s: owned by "
+						"dead node %u, this node was "
+						"dropping its ref when master died. "
+						"continue, purging the lockres.\n",
+						dlm->name, res->lockname.len,
+						res->lockname.name, dead_node);
+					dlm_lockres_get(res);
+					__dlm_do_purge_lockres(dlm, res);
+					spin_unlock(&res->spinlock);
+					wake_up(&res->wq);
+					dlm_lockres_put(res);
+					continue;
+				}
+				dlm_move_lockres_to_recovery_list(dlm, res);
+			} else if (res->owner == dlm->node_num) {
+				dlm_free_dead_locks(dlm, res, dead_node);
+				__dlm_lockres_calc_usage(dlm, res);
+			} else if (res->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
+				if (test_bit(dead_node, res->refmap)) {
+					mlog(0, "%s:%.*s: dead node %u had a ref, but had "
+						"no locks and had not purged before dying\n",
+						dlm->name, res->lockname.len,
+						res->lockname.name, dead_node);
+					dlm_lockres_clear_refmap_bit(dlm, res, dead_node);
+				}
+			}
+			spin_unlock(&res->spinlock);
+		}
+	}
+
+}
+
+static void __dlm_hb_node_down(struct dlm_ctxt *dlm, int idx)
+{
+	assert_spin_locked(&dlm->spinlock);
+
+	if (dlm->reco.new_master == idx) {
+		mlog(0, "%s: recovery master %d just died\n",
+		     dlm->name, idx);
+		if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
+			/* finalize1 was reached, so it is safe to clear
+			 * the new_master and dead_node.  that recovery
+			 * is complete. */
+			mlog(0, "%s: dead master %d had reached "
+			     "finalize1 state, clearing\n", dlm->name, idx);
+			dlm->reco.state &= ~DLM_RECO_STATE_FINALIZE;
+			__dlm_reset_recovery(dlm);
+		}
+	}
+
+	/* Clean up join state on node death. */
+	if (dlm->joining_node == idx) {
+		mlog(0, "Clearing join state for node %u\n", idx);
+		__dlm_set_joining_node(dlm, DLM_LOCK_RES_OWNER_UNKNOWN);
+	}
+
+	/* check to see if the node is already considered dead */
+	if (!test_bit(idx, dlm->live_nodes_map)) {
+		mlog(0, "for domain %s, node %d is already dead. "
+		     "another node likely did recovery already.\n",
+		     dlm->name, idx);
+		return;
+	}
+
+	/* check to see if we do not care about this node */
+	if (!test_bit(idx, dlm->domain_map)) {
+		/* This also catches the case that we get a node down
+		 * but haven't joined the domain yet. */
+		mlog(0, "node %u already removed from domain!\n", idx);
+		return;
+	}
+
+	clear_bit(idx, dlm->live_nodes_map);
+
+	/* make sure local cleanup occurs before the heartbeat events */
+	if (!test_bit(idx, dlm->recovery_map))
+		dlm_do_local_recovery_cleanup(dlm, idx);
+
+	/* notify anything attached to the heartbeat events */
+	dlm_hb_event_notify_attached(dlm, idx, 0);
+
+	mlog(0, "node %u being removed from domain map!\n", idx);
+	clear_bit(idx, dlm->domain_map);
+	clear_bit(idx, dlm->exit_domain_map);
+	/* wake up migration waiters if a node goes down.
+	 * perhaps later we can genericize this for other waiters. */
+	wake_up(&dlm->migration_wq);
+
+	set_bit(idx, dlm->recovery_map);
+}
+
+void dlm_hb_node_down_cb(struct o2nm_node *node, int idx, void *data)
+{
+	struct dlm_ctxt *dlm = data;
+
+	if (!dlm_grab(dlm))
+		return;
+
+	/*
+	 * This will notify any dlm users that a node in our domain
+	 * went away without notifying us first.
+	 */
+	if (test_bit(idx, dlm->domain_map))
+		dlm_fire_domain_eviction_callbacks(dlm, idx);
+
+	spin_lock(&dlm->spinlock);
+	__dlm_hb_node_down(dlm, idx);
+	spin_unlock(&dlm->spinlock);
+
+	dlm_put(dlm);
+}
+
+void dlm_hb_node_up_cb(struct o2nm_node *node, int idx, void *data)
+{
+	struct dlm_ctxt *dlm = data;
+
+	if (!dlm_grab(dlm))
+		return;
+
+	spin_lock(&dlm->spinlock);
+	set_bit(idx, dlm->live_nodes_map);
+	/* do NOT notify mle attached to the heartbeat events.
+	 * new nodes are not interesting in mastery until joined. */
+	spin_unlock(&dlm->spinlock);
+
+	dlm_put(dlm);
+}
+
+static void dlm_reco_ast(void *astdata)
+{
+	struct dlm_ctxt *dlm = astdata;
+	mlog(0, "ast for recovery lock fired!, this=%u, dlm=%s\n",
+	     dlm->node_num, dlm->name);
+}
+static void dlm_reco_bast(void *astdata, int blocked_type)
+{
+	struct dlm_ctxt *dlm = astdata;
+	mlog(0, "bast for recovery lock fired!, this=%u, dlm=%s\n",
+	     dlm->node_num, dlm->name);
+}
+static void dlm_reco_unlock_ast(void *astdata, enum dlm_status st)
+{
+	mlog(0, "unlockast for recovery lock fired!\n");
+}
+
+/*
+ * dlm_pick_recovery_master will continually attempt to use
+ * dlmlock() on the special "$RECOVERY" lockres with the
+ * LKM_NOQUEUE flag to get an EX.  every thread that enters
+ * this function on each node racing to become the recovery
+ * master will not stop attempting this until either:
+ * a) this node gets the EX (and becomes the recovery master),
+ * or b) dlm->reco.new_master gets set to some nodenum
+ * != O2NM_INVALID_NODE_NUM (another node will do the reco).
+ * so each time a recovery master is needed, the entire cluster
+ * will sync at this point.  if the new master dies, that will
+ * be detected in dlm_do_recovery */
+static int dlm_pick_recovery_master(struct dlm_ctxt *dlm)
+{
+	enum dlm_status ret;
+	struct dlm_lockstatus lksb;
+	int status = -EINVAL;
+
+	mlog(0, "starting recovery of %s at %lu, dead=%u, this=%u\n",
+	     dlm->name, jiffies, dlm->reco.dead_node, dlm->node_num);
+again:
+	memset(&lksb, 0, sizeof(lksb));
+
+	ret = dlmlock(dlm, LKM_EXMODE, &lksb, LKM_NOQUEUE|LKM_RECOVERY,
+		      DLM_RECOVERY_LOCK_NAME, DLM_RECOVERY_LOCK_NAME_LEN,
+		      dlm_reco_ast, dlm, dlm_reco_bast);
+
+	mlog(0, "%s: dlmlock($RECOVERY) returned %d, lksb=%d\n",
+	     dlm->name, ret, lksb.status);
+
+	if (ret == DLM_NORMAL) {
+		mlog(0, "dlm=%s dlmlock says I got it (this=%u)\n",
+		     dlm->name, dlm->node_num);
+
+		/* got the EX lock.  check to see if another node
+		 * just became the reco master */
+		if (dlm_reco_master_ready(dlm)) {
+			mlog(0, "%s: got reco EX lock, but %u will "
+			     "do the recovery\n", dlm->name,
+			     dlm->reco.new_master);
+			status = -EEXIST;
+		} else {
+			status = 0;
+
+			/* see if recovery was already finished elsewhere */
+			spin_lock(&dlm->spinlock);
+			if (dlm->reco.dead_node == O2NM_INVALID_NODE_NUM) {
+				status = -EINVAL;
+				mlog(0, "%s: got reco EX lock, but "
+				     "node got recovered already\n", dlm->name);
+				if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM) {
+					mlog(ML_ERROR, "%s: new master is %u "
+					     "but no dead node!\n",
+					     dlm->name, dlm->reco.new_master);
+					BUG();
+				}
+			}
+			spin_unlock(&dlm->spinlock);
+		}
+
+		/* if this node has actually become the recovery master,
+		 * set the master and send the messages to begin recovery */
+		if (!status) {
+			mlog(0, "%s: dead=%u, this=%u, sending "
+			     "begin_reco now\n", dlm->name,
+			     dlm->reco.dead_node, dlm->node_num);
+			status = dlm_send_begin_reco_message(dlm,
+				      dlm->reco.dead_node);
+			/* this always succeeds */
+			BUG_ON(status);
+
+			/* set the new_master to this node */
+			spin_lock(&dlm->spinlock);
+			dlm_set_reco_master(dlm, dlm->node_num);
+			spin_unlock(&dlm->spinlock);
+		}
+
+		/* recovery lock is a special case.  ast will not get fired,
+		 * so just go ahead and unlock it. */
+		ret = dlmunlock(dlm, &lksb, 0, dlm_reco_unlock_ast, dlm);
+		if (ret == DLM_DENIED) {
+			mlog(0, "got DLM_DENIED, trying LKM_CANCEL\n");
+			ret = dlmunlock(dlm, &lksb, LKM_CANCEL, dlm_reco_unlock_ast, dlm);
+		}
+		if (ret != DLM_NORMAL) {
+			/* this would really suck. this could only happen
+			 * if there was a network error during the unlock
+			 * because of node death.  this means the unlock
+			 * is actually "done" and the lock structure is
+			 * even freed.  we can continue, but only
+			 * because this specific lock name is special. */
+			mlog(ML_ERROR, "dlmunlock returned %d\n", ret);
+		}
+	} else if (ret == DLM_NOTQUEUED) {
+		mlog(0, "dlm=%s dlmlock says another node got it (this=%u)\n",
+		     dlm->name, dlm->node_num);
+		/* another node is master. wait on
+		 * reco.new_master != O2NM_INVALID_NODE_NUM
+		 * for at most one second */
+		wait_event_timeout(dlm->dlm_reco_thread_wq,
+					 dlm_reco_master_ready(dlm),
+					 msecs_to_jiffies(1000));
+		if (!dlm_reco_master_ready(dlm)) {
+			mlog(0, "%s: reco master taking awhile\n",
+			     dlm->name);
+			goto again;
+		}
+		/* another node has informed this one that it is reco master */
+		mlog(0, "%s: reco master %u is ready to recover %u\n",
+		     dlm->name, dlm->reco.new_master, dlm->reco.dead_node);
+		status = -EEXIST;
+	} else if (ret == DLM_RECOVERING) {
+		mlog(0, "dlm=%s dlmlock says master node died (this=%u)\n",
+		     dlm->name, dlm->node_num);
+		goto again;
+	} else {
+		struct dlm_lock_resource *res;
+
+		/* dlmlock returned something other than NOTQUEUED or NORMAL */
+		mlog(ML_ERROR, "%s: got %s from dlmlock($RECOVERY), "
+		     "lksb.status=%s\n", dlm->name, dlm_errname(ret),
+		     dlm_errname(lksb.status));
+		res = dlm_lookup_lockres(dlm, DLM_RECOVERY_LOCK_NAME,
+					 DLM_RECOVERY_LOCK_NAME_LEN);
+		if (res) {
+			dlm_print_one_lock_resource(res);
+			dlm_lockres_put(res);
+		} else {
+			mlog(ML_ERROR, "recovery lock not found\n");
+		}
+		BUG();
+	}
+
+	return status;
+}
+
+static int dlm_send_begin_reco_message(struct dlm_ctxt *dlm, u8 dead_node)
+{
+	struct dlm_begin_reco br;
+	int ret = 0;
+	struct dlm_node_iter iter;
+	int nodenum;
+	int status;
+
+	mlog(0, "%s: dead node is %u\n", dlm->name, dead_node);
+
+	spin_lock(&dlm->spinlock);
+	dlm_node_iter_init(dlm->domain_map, &iter);
+	spin_unlock(&dlm->spinlock);
+
+	clear_bit(dead_node, iter.node_map);
+
+	memset(&br, 0, sizeof(br));
+	br.node_idx = dlm->node_num;
+	br.dead_node = dead_node;
+
+	while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
+		ret = 0;
+		if (nodenum == dead_node) {
+			mlog(0, "not sending begin reco to dead node "
+				  "%u\n", dead_node);
+			continue;
+		}
+		if (nodenum == dlm->node_num) {
+			mlog(0, "not sending begin reco to self\n");
+			continue;
+		}
+retry:
+		mlog(0, "attempting to send begin reco msg to %d\n",
+			  nodenum);
+		ret = o2net_send_message(DLM_BEGIN_RECO_MSG, dlm->key,
+					 &br, sizeof(br), nodenum, &status);
+		/* negative status is handled ok by caller here */
+		if (ret >= 0)
+			ret = status;
+		if (dlm_is_host_down(ret)) {
+			/* node is down.  not involved in recovery
+			 * so just keep going */
+			mlog(ML_NOTICE, "%s: node %u was down when sending "
+			     "begin reco msg (%d)\n", dlm->name, nodenum, ret);
+			ret = 0;
+		}
+
+		/*
+		 * Prior to commit aad1b15310b9bcd59fa81ab8f2b1513b59553ea8,
+		 * dlm_begin_reco_handler() returned EAGAIN and not -EAGAIN.
+		 * We are handling both for compatibility reasons.
+		 */
+		if (ret == -EAGAIN || ret == EAGAIN) {
+			mlog(0, "%s: trying to start recovery of node "
+			     "%u, but node %u is waiting for last recovery "
+			     "to complete, backoff for a bit\n", dlm->name,
+			     dead_node, nodenum);
+			msleep(100);
+			goto retry;
+		}
+		if (ret < 0) {
+			struct dlm_lock_resource *res;
+
+			/* this is now a serious problem, possibly ENOMEM
+			 * in the network stack.  must retry */
+			mlog_errno(ret);
+			mlog(ML_ERROR, "begin reco of dlm %s to node %u "
+			     "returned %d\n", dlm->name, nodenum, ret);
+			res = dlm_lookup_lockres(dlm, DLM_RECOVERY_LOCK_NAME,
+						 DLM_RECOVERY_LOCK_NAME_LEN);
+			if (res) {
+				dlm_print_one_lock_resource(res);
+				dlm_lockres_put(res);
+			} else {
+				mlog(ML_ERROR, "recovery lock not found\n");
+			}
+			/* sleep for a bit in hopes that we can avoid
+			 * another ENOMEM */
+			msleep(100);
+			goto retry;
+		}
+	}
+
+	return ret;
+}
+
+int dlm_begin_reco_handler(struct o2net_msg *msg, u32 len, void *data,
+			   void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_begin_reco *br = (struct dlm_begin_reco *)msg->buf;
+
+	/* ok to return 0, domain has gone away */
+	if (!dlm_grab(dlm))
+		return 0;
+
+	spin_lock(&dlm->spinlock);
+	if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
+		mlog(0, "%s: node %u wants to recover node %u (%u:%u) "
+		     "but this node is in finalize state, waiting on finalize2\n",
+		     dlm->name, br->node_idx, br->dead_node,
+		     dlm->reco.dead_node, dlm->reco.new_master);
+		spin_unlock(&dlm->spinlock);
+		dlm_put(dlm);
+		return -EAGAIN;
+	}
+	spin_unlock(&dlm->spinlock);
+
+	mlog(0, "%s: node %u wants to recover node %u (%u:%u)\n",
+	     dlm->name, br->node_idx, br->dead_node,
+	     dlm->reco.dead_node, dlm->reco.new_master);
+
+	dlm_fire_domain_eviction_callbacks(dlm, br->dead_node);
+
+	spin_lock(&dlm->spinlock);
+	if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM) {
+		if (test_bit(dlm->reco.new_master, dlm->recovery_map)) {
+			mlog(0, "%s: new_master %u died, changing "
+			     "to %u\n", dlm->name, dlm->reco.new_master,
+			     br->node_idx);
+		} else {
+			mlog(0, "%s: new_master %u NOT DEAD, changing "
+			     "to %u\n", dlm->name, dlm->reco.new_master,
+			     br->node_idx);
+			/* may not have seen the new master as dead yet */
+		}
+	}
+	if (dlm->reco.dead_node != O2NM_INVALID_NODE_NUM) {
+		mlog(ML_NOTICE, "%s: dead_node previously set to %u, "
+		     "node %u changing it to %u\n", dlm->name,
+		     dlm->reco.dead_node, br->node_idx, br->dead_node);
+	}
+	dlm_set_reco_master(dlm, br->node_idx);
+	dlm_set_reco_dead_node(dlm, br->dead_node);
+	if (!test_bit(br->dead_node, dlm->recovery_map)) {
+		mlog(0, "recovery master %u sees %u as dead, but this "
+		     "node has not yet.  marking %u as dead\n",
+		     br->node_idx, br->dead_node, br->dead_node);
+		if (!test_bit(br->dead_node, dlm->domain_map) ||
+		    !test_bit(br->dead_node, dlm->live_nodes_map))
+			mlog(0, "%u not in domain/live_nodes map "
+			     "so setting it in reco map manually\n",
+			     br->dead_node);
+		/* force the recovery cleanup in __dlm_hb_node_down
+		 * both of these will be cleared in a moment */
+		set_bit(br->dead_node, dlm->domain_map);
+		set_bit(br->dead_node, dlm->live_nodes_map);
+		__dlm_hb_node_down(dlm, br->dead_node);
+	}
+	spin_unlock(&dlm->spinlock);
+
+	dlm_kick_recovery_thread(dlm);
+
+	mlog(0, "%s: recovery started by node %u, for %u (%u:%u)\n",
+	     dlm->name, br->node_idx, br->dead_node,
+	     dlm->reco.dead_node, dlm->reco.new_master);
+
+	dlm_put(dlm);
+	return 0;
+}
+
+#define DLM_FINALIZE_STAGE2  0x01
+static int dlm_send_finalize_reco_message(struct dlm_ctxt *dlm)
+{
+	int ret = 0;
+	struct dlm_finalize_reco fr;
+	struct dlm_node_iter iter;
+	int nodenum;
+	int status;
+	int stage = 1;
+
+	mlog(0, "finishing recovery for node %s:%u, "
+	     "stage %d\n", dlm->name, dlm->reco.dead_node, stage);
+
+	spin_lock(&dlm->spinlock);
+	dlm_node_iter_init(dlm->domain_map, &iter);
+	spin_unlock(&dlm->spinlock);
+
+stage2:
+	memset(&fr, 0, sizeof(fr));
+	fr.node_idx = dlm->node_num;
+	fr.dead_node = dlm->reco.dead_node;
+	if (stage == 2)
+		fr.flags |= DLM_FINALIZE_STAGE2;
+
+	while ((nodenum = dlm_node_iter_next(&iter)) >= 0) {
+		if (nodenum == dlm->node_num)
+			continue;
+		ret = o2net_send_message(DLM_FINALIZE_RECO_MSG, dlm->key,
+					 &fr, sizeof(fr), nodenum, &status);
+		if (ret >= 0)
+			ret = status;
+		if (ret < 0) {
+			mlog(ML_ERROR, "Error %d when sending message %u (key "
+			     "0x%x) to node %u\n", ret, DLM_FINALIZE_RECO_MSG,
+			     dlm->key, nodenum);
+			if (dlm_is_host_down(ret)) {
+				/* this has no effect on this recovery
+				 * session, so set the status to zero to
+				 * finish out the last recovery */
+				mlog(ML_ERROR, "node %u went down after this "
+				     "node finished recovery.\n", nodenum);
+				ret = 0;
+				continue;
+			}
+			break;
+		}
+	}
+	if (stage == 1) {
+		/* reset the node_iter back to the top and send finalize2 */
+		iter.curnode = -1;
+		stage = 2;
+		goto stage2;
+	}
+
+	return ret;
+}
+
+int dlm_finalize_reco_handler(struct o2net_msg *msg, u32 len, void *data,
+			      void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_finalize_reco *fr = (struct dlm_finalize_reco *)msg->buf;
+	int stage = 1;
+
+	/* ok to return 0, domain has gone away */
+	if (!dlm_grab(dlm))
+		return 0;
+
+	if (fr->flags & DLM_FINALIZE_STAGE2)
+		stage = 2;
+
+	mlog(0, "%s: node %u finalizing recovery stage%d of "
+	     "node %u (%u:%u)\n", dlm->name, fr->node_idx, stage,
+	     fr->dead_node, dlm->reco.dead_node, dlm->reco.new_master);
+
+	spin_lock(&dlm->spinlock);
+
+	if (dlm->reco.new_master != fr->node_idx) {
+		mlog(ML_ERROR, "node %u sent recovery finalize msg, but node "
+		     "%u is supposed to be the new master, dead=%u\n",
+		     fr->node_idx, dlm->reco.new_master, fr->dead_node);
+		BUG();
+	}
+	if (dlm->reco.dead_node != fr->dead_node) {
+		mlog(ML_ERROR, "node %u sent recovery finalize msg for dead "
+		     "node %u, but node %u is supposed to be dead\n",
+		     fr->node_idx, fr->dead_node, dlm->reco.dead_node);
+		BUG();
+	}
+
+	switch (stage) {
+		case 1:
+			dlm_finish_local_lockres_recovery(dlm, fr->dead_node, fr->node_idx);
+			if (dlm->reco.state & DLM_RECO_STATE_FINALIZE) {
+				mlog(ML_ERROR, "%s: received finalize1 from "
+				     "new master %u for dead node %u, but "
+				     "this node has already received it!\n",
+				     dlm->name, fr->node_idx, fr->dead_node);
+				dlm_print_reco_node_status(dlm);
+				BUG();
+			}
+			dlm->reco.state |= DLM_RECO_STATE_FINALIZE;
+			spin_unlock(&dlm->spinlock);
+			break;
+		case 2:
+			if (!(dlm->reco.state & DLM_RECO_STATE_FINALIZE)) {
+				mlog(ML_ERROR, "%s: received finalize2 from "
+				     "new master %u for dead node %u, but "
+				     "this node did not have finalize1!\n",
+				     dlm->name, fr->node_idx, fr->dead_node);
+				dlm_print_reco_node_status(dlm);
+				BUG();
+			}
+			dlm->reco.state &= ~DLM_RECO_STATE_FINALIZE;
+			__dlm_reset_recovery(dlm);
+			spin_unlock(&dlm->spinlock);
+			dlm_kick_recovery_thread(dlm);
+			break;
+	}
+
+	mlog(0, "%s: recovery done, reco master was %u, dead now %u, master now %u\n",
+	     dlm->name, fr->node_idx, dlm->reco.dead_node, dlm->reco.new_master);
+
+	dlm_put(dlm);
+	return 0;
+}
diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
new file mode 100644
index 000000000..eedf07ca2
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -0,0 +1,809 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmthread.c
+ *
+ * standalone DLM module
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/timer.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+#include "dlmdomain.h"
+
+#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_THREAD)
+#include "../cluster/masklog.h"
+
+static int dlm_thread(void *data);
+static void dlm_flush_asts(struct dlm_ctxt *dlm);
+
+/* will exit holding res->spinlock, but may drop in function */
+/* waits until flags are cleared on res->state */
+void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags)
+{
+	DECLARE_WAITQUEUE(wait, current);
+
+	assert_spin_locked(&res->spinlock);
+
+	add_wait_queue(&res->wq, &wait);
+repeat:
+	set_current_state(TASK_UNINTERRUPTIBLE);
+	if (res->state & flags) {
+		spin_unlock(&res->spinlock);
+		schedule();
+		spin_lock(&res->spinlock);
+		goto repeat;
+	}
+	remove_wait_queue(&res->wq, &wait);
+	__set_current_state(TASK_RUNNING);
+}
+
+int __dlm_lockres_has_locks(struct dlm_lock_resource *res)
+{
+	if (list_empty(&res->granted) &&
+	    list_empty(&res->converting) &&
+	    list_empty(&res->blocked))
+		return 0;
+	return 1;
+}
+
+/* "unused": the lockres has no locks, is not on the dirty list,
+ * has no inflight locks (in the gap between mastery and acquiring
+ * the first lock), and has no bits in its refmap.
+ * truly ready to be freed. */
+int __dlm_lockres_unused(struct dlm_lock_resource *res)
+{
+	int bit;
+
+	assert_spin_locked(&res->spinlock);
+
+	if (__dlm_lockres_has_locks(res))
+		return 0;
+
+	/* Locks are in the process of being created */
+	if (res->inflight_locks)
+		return 0;
+
+	if (!list_empty(&res->dirty) || res->state & DLM_LOCK_RES_DIRTY)
+		return 0;
+
+	if (res->state & (DLM_LOCK_RES_RECOVERING|
+			DLM_LOCK_RES_RECOVERY_WAITING))
+		return 0;
+
+	/* Another node has this resource with this node as the master */
+	bit = find_first_bit(res->refmap, O2NM_MAX_NODES);
+	if (bit < O2NM_MAX_NODES)
+		return 0;
+
+	return 1;
+}
+
+
+/* Call whenever you may have added or deleted something from one of
+ * the lockres queue's. This will figure out whether it belongs on the
+ * unused list or not and does the appropriate thing. */
+void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+			      struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	if (__dlm_lockres_unused(res)){
+		if (list_empty(&res->purge)) {
+			mlog(0, "%s: Adding res %.*s to purge list\n",
+			     dlm->name, res->lockname.len, res->lockname.name);
+
+			res->last_used = jiffies;
+			dlm_lockres_get(res);
+			list_add_tail(&res->purge, &dlm->purge_list);
+			dlm->purge_count++;
+		}
+	} else if (!list_empty(&res->purge)) {
+		mlog(0, "%s: Removing res %.*s from purge list\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+
+		list_del_init(&res->purge);
+		dlm_lockres_put(res);
+		dlm->purge_count--;
+	}
+}
+
+void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
+			    struct dlm_lock_resource *res)
+{
+	spin_lock(&dlm->spinlock);
+	spin_lock(&res->spinlock);
+
+	__dlm_lockres_calc_usage(dlm, res);
+
+	spin_unlock(&res->spinlock);
+	spin_unlock(&dlm->spinlock);
+}
+
+/*
+ * Do the real purge work:
+ *     unhash the lockres, and
+ *     clear flag DLM_LOCK_RES_DROPPING_REF.
+ * It requires dlm and lockres spinlock to be taken.
+ */
+void __dlm_do_purge_lockres(struct dlm_ctxt *dlm,
+		struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	if (!list_empty(&res->purge)) {
+		mlog(0, "%s: Removing res %.*s from purgelist\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		list_del_init(&res->purge);
+		dlm_lockres_put(res);
+		dlm->purge_count--;
+	}
+
+	if (!__dlm_lockres_unused(res)) {
+		mlog(ML_ERROR, "%s: res %.*s in use after deref\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		__dlm_print_one_lock_resource(res);
+		BUG();
+	}
+
+	__dlm_unhash_lockres(dlm, res);
+
+	spin_lock(&dlm->track_lock);
+	if (!list_empty(&res->tracking))
+		list_del_init(&res->tracking);
+	else {
+		mlog(ML_ERROR, "%s: Resource %.*s not on the Tracking list\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		__dlm_print_one_lock_resource(res);
+	}
+	spin_unlock(&dlm->track_lock);
+
+	/*
+	 * lockres is not in the hash now. drop the flag and wake up
+	 * any processes waiting in dlm_get_lock_resource.
+	 */
+	res->state &= ~DLM_LOCK_RES_DROPPING_REF;
+}
+
+static void dlm_purge_lockres(struct dlm_ctxt *dlm,
+			     struct dlm_lock_resource *res)
+{
+	int master;
+	int ret = 0;
+
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	master = (res->owner == dlm->node_num);
+
+	mlog(0, "%s: Purging res %.*s, master %d\n", dlm->name,
+	     res->lockname.len, res->lockname.name, master);
+
+	if (!master) {
+		if (res->state & DLM_LOCK_RES_DROPPING_REF) {
+			mlog(ML_NOTICE, "%s: res %.*s already in DLM_LOCK_RES_DROPPING_REF state\n",
+				dlm->name, res->lockname.len, res->lockname.name);
+			spin_unlock(&res->spinlock);
+			return;
+		}
+
+		res->state |= DLM_LOCK_RES_DROPPING_REF;
+		/* drop spinlock...  retake below */
+		spin_unlock(&res->spinlock);
+		spin_unlock(&dlm->spinlock);
+
+		spin_lock(&res->spinlock);
+		/* This ensures that clear refmap is sent after the set */
+		__dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
+		spin_unlock(&res->spinlock);
+
+		/* clear our bit from the master's refmap, ignore errors */
+		ret = dlm_drop_lockres_ref(dlm, res);
+		if (ret < 0) {
+			if (!dlm_is_host_down(ret))
+				BUG();
+		}
+		spin_lock(&dlm->spinlock);
+		spin_lock(&res->spinlock);
+	}
+
+	if (!list_empty(&res->purge)) {
+		mlog(0, "%s: Removing res %.*s from purgelist, master %d\n",
+		     dlm->name, res->lockname.len, res->lockname.name, master);
+		list_del_init(&res->purge);
+		dlm_lockres_put(res);
+		dlm->purge_count--;
+	}
+
+	if (!master && ret == DLM_DEREF_RESPONSE_INPROG) {
+		mlog(0, "%s: deref %.*s in progress\n",
+			dlm->name, res->lockname.len, res->lockname.name);
+		spin_unlock(&res->spinlock);
+		return;
+	}
+
+	if (!__dlm_lockres_unused(res)) {
+		mlog(ML_ERROR, "%s: res %.*s in use after deref\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		__dlm_print_one_lock_resource(res);
+		BUG();
+	}
+
+	__dlm_unhash_lockres(dlm, res);
+
+	spin_lock(&dlm->track_lock);
+	if (!list_empty(&res->tracking))
+		list_del_init(&res->tracking);
+	else {
+		mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n",
+				res->lockname.len, res->lockname.name);
+		__dlm_print_one_lock_resource(res);
+	}
+	spin_unlock(&dlm->track_lock);
+
+	/* lockres is not in the hash now.  drop the flag and wake up
+	 * any processes waiting in dlm_get_lock_resource. */
+	if (!master) {
+		res->state &= ~DLM_LOCK_RES_DROPPING_REF;
+		spin_unlock(&res->spinlock);
+		wake_up(&res->wq);
+	} else
+		spin_unlock(&res->spinlock);
+}
+
+static void dlm_run_purge_list(struct dlm_ctxt *dlm,
+			       int purge_now)
+{
+	unsigned int run_max, unused;
+	unsigned long purge_jiffies;
+	struct dlm_lock_resource *lockres;
+
+	spin_lock(&dlm->spinlock);
+	run_max = dlm->purge_count;
+
+	while(run_max && !list_empty(&dlm->purge_list)) {
+		run_max--;
+
+		lockres = list_entry(dlm->purge_list.next,
+				     struct dlm_lock_resource, purge);
+
+		spin_lock(&lockres->spinlock);
+
+		purge_jiffies = lockres->last_used +
+			msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
+
+		/* Make sure that we want to be processing this guy at
+		 * this time. */
+		if (!purge_now && time_after(purge_jiffies, jiffies)) {
+			/* Since resources are added to the purge list
+			 * in tail order, we can stop at the first
+			 * unpurgable resource -- anyone added after
+			 * him will have a greater last_used value */
+			spin_unlock(&lockres->spinlock);
+			break;
+		}
+
+		/* Status of the lockres *might* change so double
+		 * check. If the lockres is unused, holding the dlm
+		 * spinlock will prevent people from getting and more
+		 * refs on it. */
+		unused = __dlm_lockres_unused(lockres);
+		if (!unused ||
+		    (lockres->state & DLM_LOCK_RES_MIGRATING) ||
+		    (lockres->inflight_assert_workers != 0)) {
+			mlog(0, "%s: res %.*s is in use or being remastered, "
+			     "used %d, state %d, assert master workers %u\n",
+			     dlm->name, lockres->lockname.len,
+			     lockres->lockname.name,
+			     !unused, lockres->state,
+			     lockres->inflight_assert_workers);
+			list_move_tail(&lockres->purge, &dlm->purge_list);
+			spin_unlock(&lockres->spinlock);
+			continue;
+		}
+
+		dlm_lockres_get(lockres);
+
+		dlm_purge_lockres(dlm, lockres);
+
+		dlm_lockres_put(lockres);
+
+		/* Avoid adding any scheduling latencies */
+		cond_resched_lock(&dlm->spinlock);
+	}
+
+	spin_unlock(&dlm->spinlock);
+}
+
+static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
+			      struct dlm_lock_resource *res)
+{
+	struct dlm_lock *lock, *target;
+	int can_grant = 1;
+
+	/*
+	 * Because this function is called with the lockres
+	 * spinlock, and because we know that it is not migrating/
+	 * recovering/in-progress, it is fine to reserve asts and
+	 * basts right before queueing them all throughout
+	 */
+	assert_spin_locked(&dlm->ast_lock);
+	assert_spin_locked(&res->spinlock);
+	BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
+			      DLM_LOCK_RES_RECOVERING|
+			      DLM_LOCK_RES_IN_PROGRESS)));
+
+converting:
+	if (list_empty(&res->converting))
+		goto blocked;
+	mlog(0, "%s: res %.*s has locks on the convert queue\n", dlm->name,
+	     res->lockname.len, res->lockname.name);
+
+	target = list_entry(res->converting.next, struct dlm_lock, list);
+	if (target->ml.convert_type == LKM_IVMODE) {
+		mlog(ML_ERROR, "%s: res %.*s converting lock to invalid mode\n",
+		     dlm->name, res->lockname.len, res->lockname.name);
+		BUG();
+	}
+	list_for_each_entry(lock, &res->granted, list) {
+		if (lock==target)
+			continue;
+		if (!dlm_lock_compatible(lock->ml.type,
+					 target->ml.convert_type)) {
+			can_grant = 0;
+			/* queue the BAST if not already */
+			if (lock->ml.highest_blocked == LKM_IVMODE) {
+				__dlm_lockres_reserve_ast(res);
+				__dlm_queue_bast(dlm, lock);
+			}
+			/* update the highest_blocked if needed */
+			if (lock->ml.highest_blocked < target->ml.convert_type)
+				lock->ml.highest_blocked =
+					target->ml.convert_type;
+		}
+	}
+
+	list_for_each_entry(lock, &res->converting, list) {
+		if (lock==target)
+			continue;
+		if (!dlm_lock_compatible(lock->ml.type,
+					 target->ml.convert_type)) {
+			can_grant = 0;
+			if (lock->ml.highest_blocked == LKM_IVMODE) {
+				__dlm_lockres_reserve_ast(res);
+				__dlm_queue_bast(dlm, lock);
+			}
+			if (lock->ml.highest_blocked < target->ml.convert_type)
+				lock->ml.highest_blocked =
+					target->ml.convert_type;
+		}
+	}
+
+	/* we can convert the lock */
+	if (can_grant) {
+		spin_lock(&target->spinlock);
+		BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
+
+		mlog(0, "%s: res %.*s, AST for Converting lock %u:%llu, type "
+		     "%d => %d, node %u\n", dlm->name, res->lockname.len,
+		     res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
+		     target->ml.type,
+		     target->ml.convert_type, target->ml.node);
+
+		target->ml.type = target->ml.convert_type;
+		target->ml.convert_type = LKM_IVMODE;
+		list_move_tail(&target->list, &res->granted);
+
+		BUG_ON(!target->lksb);
+		target->lksb->status = DLM_NORMAL;
+
+		spin_unlock(&target->spinlock);
+
+		__dlm_lockres_reserve_ast(res);
+		__dlm_queue_ast(dlm, target);
+		/* go back and check for more */
+		goto converting;
+	}
+
+blocked:
+	if (list_empty(&res->blocked))
+		goto leave;
+	target = list_entry(res->blocked.next, struct dlm_lock, list);
+
+	list_for_each_entry(lock, &res->granted, list) {
+		if (lock==target)
+			continue;
+		if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
+			can_grant = 0;
+			if (lock->ml.highest_blocked == LKM_IVMODE) {
+				__dlm_lockres_reserve_ast(res);
+				__dlm_queue_bast(dlm, lock);
+			}
+			if (lock->ml.highest_blocked < target->ml.type)
+				lock->ml.highest_blocked = target->ml.type;
+		}
+	}
+
+	list_for_each_entry(lock, &res->converting, list) {
+		if (lock==target)
+			continue;
+		if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
+			can_grant = 0;
+			if (lock->ml.highest_blocked == LKM_IVMODE) {
+				__dlm_lockres_reserve_ast(res);
+				__dlm_queue_bast(dlm, lock);
+			}
+			if (lock->ml.highest_blocked < target->ml.type)
+				lock->ml.highest_blocked = target->ml.type;
+		}
+	}
+
+	/* we can grant the blocked lock (only
+	 * possible if converting list empty) */
+	if (can_grant) {
+		spin_lock(&target->spinlock);
+		BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
+
+		mlog(0, "%s: res %.*s, AST for Blocked lock %u:%llu, type %d, "
+		     "node %u\n", dlm->name, res->lockname.len,
+		     res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
+		     target->ml.type, target->ml.node);
+
+		/* target->ml.type is already correct */
+		list_move_tail(&target->list, &res->granted);
+
+		BUG_ON(!target->lksb);
+		target->lksb->status = DLM_NORMAL;
+
+		spin_unlock(&target->spinlock);
+
+		__dlm_lockres_reserve_ast(res);
+		__dlm_queue_ast(dlm, target);
+		/* go back and check for more */
+		goto converting;
+	}
+
+leave:
+	return;
+}
+
+/* must have NO locks when calling this with res !=NULL * */
+void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+	if (res) {
+		spin_lock(&dlm->spinlock);
+		spin_lock(&res->spinlock);
+		__dlm_dirty_lockres(dlm, res);
+		spin_unlock(&res->spinlock);
+		spin_unlock(&dlm->spinlock);
+	}
+	wake_up(&dlm->dlm_thread_wq);
+}
+
+void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
+{
+	assert_spin_locked(&dlm->spinlock);
+	assert_spin_locked(&res->spinlock);
+
+	/* don't shuffle secondary queues */
+	if (res->owner == dlm->node_num) {
+		if (res->state & (DLM_LOCK_RES_MIGRATING |
+				  DLM_LOCK_RES_BLOCK_DIRTY))
+		    return;
+
+		if (list_empty(&res->dirty)) {
+			/* ref for dirty_list */
+			dlm_lockres_get(res);
+			list_add_tail(&res->dirty, &dlm->dirty_list);
+			res->state |= DLM_LOCK_RES_DIRTY;
+		}
+	}
+
+	mlog(0, "%s: res %.*s\n", dlm->name, res->lockname.len,
+	     res->lockname.name);
+}
+
+
+/* Launch the NM thread for the mounted volume */
+int dlm_launch_thread(struct dlm_ctxt *dlm)
+{
+	mlog(0, "Starting dlm_thread...\n");
+
+	dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm-%s",
+			dlm->name);
+	if (IS_ERR(dlm->dlm_thread_task)) {
+		mlog_errno(PTR_ERR(dlm->dlm_thread_task));
+		dlm->dlm_thread_task = NULL;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+void dlm_complete_thread(struct dlm_ctxt *dlm)
+{
+	if (dlm->dlm_thread_task) {
+		mlog(ML_KTHREAD, "Waiting for dlm thread to exit\n");
+		kthread_stop(dlm->dlm_thread_task);
+		dlm->dlm_thread_task = NULL;
+	}
+}
+
+static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
+{
+	int empty;
+
+	spin_lock(&dlm->spinlock);
+	empty = list_empty(&dlm->dirty_list);
+	spin_unlock(&dlm->spinlock);
+
+	return empty;
+}
+
+static void dlm_flush_asts(struct dlm_ctxt *dlm)
+{
+	int ret;
+	struct dlm_lock *lock;
+	struct dlm_lock_resource *res;
+	u8 hi;
+
+	spin_lock(&dlm->ast_lock);
+	while (!list_empty(&dlm->pending_asts)) {
+		lock = list_entry(dlm->pending_asts.next,
+				  struct dlm_lock, ast_list);
+		/* get an extra ref on lock */
+		dlm_lock_get(lock);
+		res = lock->lockres;
+		mlog(0, "%s: res %.*s, Flush AST for lock %u:%llu, type %d, "
+		     "node %u\n", dlm->name, res->lockname.len,
+		     res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     lock->ml.type, lock->ml.node);
+
+		BUG_ON(!lock->ast_pending);
+
+		/* remove from list (including ref) */
+		list_del_init(&lock->ast_list);
+		dlm_lock_put(lock);
+		spin_unlock(&dlm->ast_lock);
+
+		if (lock->ml.node != dlm->node_num) {
+			ret = dlm_do_remote_ast(dlm, res, lock);
+			if (ret < 0)
+				mlog_errno(ret);
+		} else
+			dlm_do_local_ast(dlm, res, lock);
+
+		spin_lock(&dlm->ast_lock);
+
+		/* possible that another ast was queued while
+		 * we were delivering the last one */
+		if (!list_empty(&lock->ast_list)) {
+			mlog(0, "%s: res %.*s, AST queued while flushing last "
+			     "one\n", dlm->name, res->lockname.len,
+			     res->lockname.name);
+		} else
+			lock->ast_pending = 0;
+
+		/* drop the extra ref.
+		 * this may drop it completely. */
+		dlm_lock_put(lock);
+		dlm_lockres_release_ast(dlm, res);
+	}
+
+	while (!list_empty(&dlm->pending_basts)) {
+		lock = list_entry(dlm->pending_basts.next,
+				  struct dlm_lock, bast_list);
+		/* get an extra ref on lock */
+		dlm_lock_get(lock);
+		res = lock->lockres;
+
+		BUG_ON(!lock->bast_pending);
+
+		/* get the highest blocked lock, and reset */
+		spin_lock(&lock->spinlock);
+		BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
+		hi = lock->ml.highest_blocked;
+		lock->ml.highest_blocked = LKM_IVMODE;
+		spin_unlock(&lock->spinlock);
+
+		/* remove from list (including ref) */
+		list_del_init(&lock->bast_list);
+		dlm_lock_put(lock);
+		spin_unlock(&dlm->ast_lock);
+
+		mlog(0, "%s: res %.*s, Flush BAST for lock %u:%llu, "
+		     "blocked %d, node %u\n",
+		     dlm->name, res->lockname.len, res->lockname.name,
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     hi, lock->ml.node);
+
+		if (lock->ml.node != dlm->node_num) {
+			ret = dlm_send_proxy_bast(dlm, res, lock, hi);
+			if (ret < 0)
+				mlog_errno(ret);
+		} else
+			dlm_do_local_bast(dlm, res, lock, hi);
+
+		spin_lock(&dlm->ast_lock);
+
+		/* possible that another bast was queued while
+		 * we were delivering the last one */
+		if (!list_empty(&lock->bast_list)) {
+			mlog(0, "%s: res %.*s, BAST queued while flushing last "
+			     "one\n", dlm->name, res->lockname.len,
+			     res->lockname.name);
+		} else
+			lock->bast_pending = 0;
+
+		/* drop the extra ref.
+		 * this may drop it completely. */
+		dlm_lock_put(lock);
+		dlm_lockres_release_ast(dlm, res);
+	}
+	wake_up(&dlm->ast_wq);
+	spin_unlock(&dlm->ast_lock);
+}
+
+
+#define DLM_THREAD_TIMEOUT_MS (4 * 1000)
+#define DLM_THREAD_MAX_DIRTY  100
+
+static int dlm_thread(void *data)
+{
+	struct dlm_lock_resource *res;
+	struct dlm_ctxt *dlm = data;
+	unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
+
+	mlog(0, "dlm thread running for %s...\n", dlm->name);
+
+	while (!kthread_should_stop()) {
+		int n = DLM_THREAD_MAX_DIRTY;
+
+		/* dlm_shutting_down is very point-in-time, but that
+		 * doesn't matter as we'll just loop back around if we
+		 * get false on the leading edge of a state
+		 * transition. */
+		dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
+
+		/* We really don't want to hold dlm->spinlock while
+		 * calling dlm_shuffle_lists on each lockres that
+		 * needs to have its queues adjusted and AST/BASTs
+		 * run.  So let's pull each entry off the dirty_list
+		 * and drop dlm->spinlock ASAP.  Once off the list,
+		 * res->spinlock needs to be taken again to protect
+		 * the queues while calling dlm_shuffle_lists.  */
+		spin_lock(&dlm->spinlock);
+		while (!list_empty(&dlm->dirty_list)) {
+			int delay = 0;
+			res = list_entry(dlm->dirty_list.next,
+					 struct dlm_lock_resource, dirty);
+
+			/* peel a lockres off, remove it from the list,
+			 * unset the dirty flag and drop the dlm lock */
+			BUG_ON(!res);
+			dlm_lockres_get(res);
+
+			spin_lock(&res->spinlock);
+			/* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
+			list_del_init(&res->dirty);
+			spin_unlock(&res->spinlock);
+			spin_unlock(&dlm->spinlock);
+			/* Drop dirty_list ref */
+			dlm_lockres_put(res);
+
+		 	/* lockres can be re-dirtied/re-added to the
+			 * dirty_list in this gap, but that is ok */
+
+			spin_lock(&dlm->ast_lock);
+			spin_lock(&res->spinlock);
+			if (res->owner != dlm->node_num) {
+				__dlm_print_one_lock_resource(res);
+				mlog(ML_ERROR, "%s: inprog %d, mig %d, reco %d,"
+				     " dirty %d\n", dlm->name,
+				     !!(res->state & DLM_LOCK_RES_IN_PROGRESS),
+				     !!(res->state & DLM_LOCK_RES_MIGRATING),
+				     !!(res->state & DLM_LOCK_RES_RECOVERING),
+				     !!(res->state & DLM_LOCK_RES_DIRTY));
+			}
+			BUG_ON(res->owner != dlm->node_num);
+
+			/* it is now ok to move lockreses in these states
+			 * to the dirty list, assuming that they will only be
+			 * dirty for a short while. */
+			BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
+			if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
+					  DLM_LOCK_RES_RECOVERING |
+					  DLM_LOCK_RES_RECOVERY_WAITING)) {
+				/* move it to the tail and keep going */
+				res->state &= ~DLM_LOCK_RES_DIRTY;
+				spin_unlock(&res->spinlock);
+				spin_unlock(&dlm->ast_lock);
+				mlog(0, "%s: res %.*s, inprogress, delay list "
+				     "shuffle, state %d\n", dlm->name,
+				     res->lockname.len, res->lockname.name,
+				     res->state);
+				delay = 1;
+				goto in_progress;
+			}
+
+			/* at this point the lockres is not migrating/
+			 * recovering/in-progress.  we have the lockres
+			 * spinlock and do NOT have the dlm lock.
+			 * safe to reserve/queue asts and run the lists. */
+
+			/* called while holding lockres lock */
+			dlm_shuffle_lists(dlm, res);
+			res->state &= ~DLM_LOCK_RES_DIRTY;
+			spin_unlock(&res->spinlock);
+			spin_unlock(&dlm->ast_lock);
+
+			dlm_lockres_calc_usage(dlm, res);
+
+in_progress:
+
+			spin_lock(&dlm->spinlock);
+			/* if the lock was in-progress, stick
+			 * it on the back of the list */
+			if (delay) {
+				spin_lock(&res->spinlock);
+				__dlm_dirty_lockres(dlm, res);
+				spin_unlock(&res->spinlock);
+			}
+			dlm_lockres_put(res);
+
+			/* unlikely, but we may need to give time to
+			 * other tasks */
+			if (!--n) {
+				mlog(0, "%s: Throttling dlm thread\n",
+				     dlm->name);
+				break;
+			}
+		}
+
+		spin_unlock(&dlm->spinlock);
+		dlm_flush_asts(dlm);
+
+		/* yield and continue right away if there is more work to do */
+		if (!n) {
+			cond_resched();
+			continue;
+		}
+
+		wait_event_interruptible_timeout(dlm->dlm_thread_wq,
+						 !dlm_dirty_list_empty(dlm) ||
+						 kthread_should_stop(),
+						 timeout);
+	}
+
+	mlog(0, "quitting DLM thread\n");
+	return 0;
+}
diff --git a/fs/ocfs2/dlm/dlmunlock.c b/fs/ocfs2/dlm/dlmunlock.c
new file mode 100644
index 000000000..7318e4794
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmunlock.c
@@ -0,0 +1,695 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmunlock.c
+ *
+ * underlying calls for unlocking locks
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ */
+
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <linux/random.h>
+#include <linux/blkdev.h>
+#include <linux/socket.h>
+#include <linux/inet.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+
+#include "../cluster/heartbeat.h"
+#include "../cluster/nodemanager.h"
+#include "../cluster/tcp.h"
+
+#include "dlmapi.h"
+#include "dlmcommon.h"
+
+#define MLOG_MASK_PREFIX ML_DLM
+#include "../cluster/masklog.h"
+
+#define DLM_UNLOCK_FREE_LOCK           0x00000001
+#define DLM_UNLOCK_CALL_AST            0x00000002
+#define DLM_UNLOCK_REMOVE_LOCK         0x00000004
+#define DLM_UNLOCK_REGRANT_LOCK        0x00000008
+#define DLM_UNLOCK_CLEAR_CONVERT_TYPE  0x00000010
+
+
+static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
+					      struct dlm_lock_resource *res,
+					      struct dlm_lock *lock,
+					      struct dlm_lockstatus *lksb,
+					      int *actions);
+static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
+					      struct dlm_lock_resource *res,
+					      struct dlm_lock *lock,
+					      struct dlm_lockstatus *lksb,
+					      int *actions);
+
+static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
+						 struct dlm_lock_resource *res,
+						 struct dlm_lock *lock,
+						 struct dlm_lockstatus *lksb,
+						 int flags,
+						 u8 owner);
+
+
+/*
+ * according to the spec:
+ * http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
+ *
+ *  flags & LKM_CANCEL != 0: must be converting or blocked
+ *  flags & LKM_CANCEL == 0: must be granted
+ *
+ * So to unlock a converting lock, you must first cancel the
+ * convert (passing LKM_CANCEL in flags), then call the unlock
+ * again (with no LKM_CANCEL in flags).
+ */
+
+
+/*
+ * locking:
+ *   caller needs:  none
+ *   taken:         res->spinlock and lock->spinlock taken and dropped
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
+ * all callers should have taken an extra ref on lock coming in
+ */
+static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm,
+					struct dlm_lock_resource *res,
+					struct dlm_lock *lock,
+					struct dlm_lockstatus *lksb,
+					int flags, int *call_ast,
+					int master_node)
+{
+	enum dlm_status status;
+	int actions = 0;
+	int in_use;
+	u8 owner;
+	int recovery_wait = 0;
+
+	mlog(0, "master_node = %d, valblk = %d\n", master_node,
+	     flags & LKM_VALBLK);
+
+	if (master_node)
+		BUG_ON(res->owner != dlm->node_num);
+	else
+		BUG_ON(res->owner == dlm->node_num);
+
+	spin_lock(&dlm->ast_lock);
+	/* We want to be sure that we're not freeing a lock
+	 * that still has AST's pending... */
+	in_use = !list_empty(&lock->ast_list);
+	spin_unlock(&dlm->ast_lock);
+	if (in_use && !(flags & LKM_CANCEL)) {
+	       mlog(ML_ERROR, "lockres %.*s: Someone is calling dlmunlock "
+		    "while waiting for an ast!", res->lockname.len,
+		    res->lockname.name);
+		return DLM_BADPARAM;
+	}
+
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_IN_PROGRESS) {
+		if (master_node && !(flags & LKM_CANCEL)) {
+			mlog(ML_ERROR, "lockres in progress!\n");
+			spin_unlock(&res->spinlock);
+			return DLM_FORWARD;
+		}
+		/* ok for this to sleep if not in a network handler */
+		__dlm_wait_on_lockres(res);
+		res->state |= DLM_LOCK_RES_IN_PROGRESS;
+	}
+	spin_lock(&lock->spinlock);
+
+	if (res->state & DLM_LOCK_RES_RECOVERING) {
+		status = DLM_RECOVERING;
+		goto leave;
+	}
+
+	if (res->state & DLM_LOCK_RES_MIGRATING) {
+		status = DLM_MIGRATING;
+		goto leave;
+	}
+
+	/* see above for what the spec says about
+	 * LKM_CANCEL and the lock queue state */
+	if (flags & LKM_CANCEL)
+		status = dlm_get_cancel_actions(dlm, res, lock, lksb, &actions);
+	else
+		status = dlm_get_unlock_actions(dlm, res, lock, lksb, &actions);
+
+	if (status != DLM_NORMAL && (status != DLM_CANCELGRANT || !master_node))
+		goto leave;
+
+	/* By now this has been masked out of cancel requests. */
+	if (flags & LKM_VALBLK) {
+		/* make the final update to the lvb */
+		if (master_node)
+			memcpy(res->lvb, lksb->lvb, DLM_LVB_LEN);
+		else
+			flags |= LKM_PUT_LVB; /* let the send function
+					       * handle it. */
+	}
+
+	if (!master_node) {
+		owner = res->owner;
+		/* drop locks and send message */
+		if (flags & LKM_CANCEL)
+			lock->cancel_pending = 1;
+		else
+			lock->unlock_pending = 1;
+		spin_unlock(&lock->spinlock);
+		spin_unlock(&res->spinlock);
+		status = dlm_send_remote_unlock_request(dlm, res, lock, lksb,
+							flags, owner);
+		spin_lock(&res->spinlock);
+		spin_lock(&lock->spinlock);
+		/* if the master told us the lock was already granted,
+		 * let the ast handle all of these actions */
+		if (status == DLM_CANCELGRANT) {
+			actions &= ~(DLM_UNLOCK_REMOVE_LOCK|
+				     DLM_UNLOCK_REGRANT_LOCK|
+				     DLM_UNLOCK_CLEAR_CONVERT_TYPE);
+		} else if (status == DLM_RECOVERING ||
+			   status == DLM_MIGRATING ||
+			   status == DLM_FORWARD ||
+			   status == DLM_NOLOCKMGR
+			   ) {
+			/* must clear the actions because this unlock
+			 * is about to be retried.  cannot free or do
+			 * any list manipulation. */
+			mlog(0, "%s:%.*s: clearing actions, %s\n",
+			     dlm->name, res->lockname.len,
+			     res->lockname.name,
+			     status==DLM_RECOVERING?"recovering":
+			     (status==DLM_MIGRATING?"migrating":
+				(status == DLM_FORWARD ? "forward" :
+						"nolockmanager")));
+			actions = 0;
+		}
+		if (flags & LKM_CANCEL)
+			lock->cancel_pending = 0;
+		else {
+			if (!lock->unlock_pending)
+				recovery_wait = 1;
+			else
+				lock->unlock_pending = 0;
+		}
+	}
+
+	/* get an extra ref on lock.  if we are just switching
+	 * lists here, we dont want the lock to go away. */
+	dlm_lock_get(lock);
+
+	if (actions & DLM_UNLOCK_REMOVE_LOCK) {
+		list_del_init(&lock->list);
+		dlm_lock_put(lock);
+	}
+	if (actions & DLM_UNLOCK_REGRANT_LOCK) {
+		dlm_lock_get(lock);
+		list_add_tail(&lock->list, &res->granted);
+	}
+	if (actions & DLM_UNLOCK_CLEAR_CONVERT_TYPE) {
+		mlog(0, "clearing convert_type at %smaster node\n",
+		     master_node ? "" : "non-");
+		lock->ml.convert_type = LKM_IVMODE;
+	}
+
+	/* remove the extra ref on lock */
+	dlm_lock_put(lock);
+
+leave:
+	res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
+	if (!dlm_lock_on_list(&res->converting, lock))
+		BUG_ON(lock->ml.convert_type != LKM_IVMODE);
+	else
+		BUG_ON(lock->ml.convert_type == LKM_IVMODE);
+	spin_unlock(&lock->spinlock);
+	spin_unlock(&res->spinlock);
+	wake_up(&res->wq);
+
+	if (recovery_wait) {
+		spin_lock(&res->spinlock);
+		/* Unlock request will directly succeed after owner dies,
+		 * and the lock is already removed from grant list. We have to
+		 * wait for RECOVERING done or we miss the chance to purge it
+		 * since the removement is much faster than RECOVERING proc.
+		 */
+		__dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_RECOVERING);
+		spin_unlock(&res->spinlock);
+	}
+
+	/* let the caller's final dlm_lock_put handle the actual kfree */
+	if (actions & DLM_UNLOCK_FREE_LOCK) {
+		/* this should always be coupled with list removal */
+		BUG_ON(!(actions & DLM_UNLOCK_REMOVE_LOCK));
+		mlog(0, "lock %u:%llu should be gone now! refs=%d\n",
+		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		     kref_read(&lock->lock_refs)-1);
+		dlm_lock_put(lock);
+	}
+	if (actions & DLM_UNLOCK_CALL_AST)
+		*call_ast = 1;
+
+	/* if cancel or unlock succeeded, lvb work is done */
+	if (status == DLM_NORMAL)
+		lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
+
+	return status;
+}
+
+void dlm_commit_pending_unlock(struct dlm_lock_resource *res,
+			       struct dlm_lock *lock)
+{
+	/* leave DLM_LKSB_PUT_LVB on the lksb so any final
+	 * update of the lvb will be sent to the new master */
+	list_del_init(&lock->list);
+}
+
+void dlm_commit_pending_cancel(struct dlm_lock_resource *res,
+			       struct dlm_lock *lock)
+{
+	list_move_tail(&lock->list, &res->granted);
+	lock->ml.convert_type = LKM_IVMODE;
+}
+
+
+static inline enum dlm_status dlmunlock_master(struct dlm_ctxt *dlm,
+					  struct dlm_lock_resource *res,
+					  struct dlm_lock *lock,
+					  struct dlm_lockstatus *lksb,
+					  int flags,
+					  int *call_ast)
+{
+	return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 1);
+}
+
+static inline enum dlm_status dlmunlock_remote(struct dlm_ctxt *dlm,
+					  struct dlm_lock_resource *res,
+					  struct dlm_lock *lock,
+					  struct dlm_lockstatus *lksb,
+					  int flags, int *call_ast)
+{
+	return dlmunlock_common(dlm, res, lock, lksb, flags, call_ast, 0);
+}
+
+/*
+ * locking:
+ *   caller needs:  none
+ *   taken:         none
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_NOLOCKMGR, status from network
+ */
+static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm,
+						 struct dlm_lock_resource *res,
+						 struct dlm_lock *lock,
+						 struct dlm_lockstatus *lksb,
+						 int flags,
+						 u8 owner)
+{
+	struct dlm_unlock_lock unlock;
+	int tmpret;
+	enum dlm_status ret;
+	int status = 0;
+	struct kvec vec[2];
+	size_t veclen = 1;
+
+	mlog(0, "%.*s\n", res->lockname.len, res->lockname.name);
+
+	if (owner == dlm->node_num) {
+		/* ended up trying to contact ourself.  this means
+		 * that the lockres had been remote but became local
+		 * via a migration.  just retry it, now as local */
+		mlog(0, "%s:%.*s: this node became the master due to a "
+		     "migration, re-evaluate now\n", dlm->name,
+		     res->lockname.len, res->lockname.name);
+		return DLM_FORWARD;
+	}
+
+	memset(&unlock, 0, sizeof(unlock));
+	unlock.node_idx = dlm->node_num;
+	unlock.flags = cpu_to_be32(flags);
+	unlock.cookie = lock->ml.cookie;
+	unlock.namelen = res->lockname.len;
+	memcpy(unlock.name, res->lockname.name, unlock.namelen);
+
+	vec[0].iov_len = sizeof(struct dlm_unlock_lock);
+	vec[0].iov_base = &unlock;
+
+	if (flags & LKM_PUT_LVB) {
+		/* extra data to send if we are updating lvb */
+		vec[1].iov_len = DLM_LVB_LEN;
+		vec[1].iov_base = lock->lksb->lvb;
+		veclen++;
+	}
+
+	tmpret = o2net_send_message_vec(DLM_UNLOCK_LOCK_MSG, dlm->key,
+					vec, veclen, owner, &status);
+	if (tmpret >= 0) {
+		// successfully sent and received
+		if (status == DLM_FORWARD)
+			mlog(0, "master was in-progress.  retry\n");
+		ret = status;
+	} else {
+		mlog(ML_ERROR, "Error %d when sending message %u (key 0x%x) to "
+		     "node %u\n", tmpret, DLM_UNLOCK_LOCK_MSG, dlm->key, owner);
+		if (dlm_is_host_down(tmpret)) {
+			/* NOTE: this seems strange, but it is what we want.
+			 * when the master goes down during a cancel or
+			 * unlock, the recovery code completes the operation
+			 * as if the master had not died, then passes the
+			 * updated state to the recovery master.  this thread
+			 * just needs to finish out the operation and call
+			 * the unlockast. */
+			if (dlm_is_node_dead(dlm, owner))
+				ret = DLM_NORMAL;
+			else
+				ret = DLM_NOLOCKMGR;
+		} else {
+			/* something bad.  this will BUG in ocfs2 */
+			ret = dlm_err_to_dlm_status(tmpret);
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * locking:
+ *   caller needs:  none
+ *   taken:         takes and drops res->spinlock
+ *   held on exit:  none
+ * returns: DLM_NORMAL, DLM_BADARGS, DLM_IVLOCKID,
+ *          return value from dlmunlock_master
+ */
+int dlm_unlock_lock_handler(struct o2net_msg *msg, u32 len, void *data,
+			    void **ret_data)
+{
+	struct dlm_ctxt *dlm = data;
+	struct dlm_unlock_lock *unlock = (struct dlm_unlock_lock *)msg->buf;
+	struct dlm_lock_resource *res = NULL;
+	struct dlm_lock *lock = NULL, *iter;
+	enum dlm_status status = DLM_NORMAL;
+	int i;
+	struct dlm_lockstatus *lksb = NULL;
+	int ignore;
+	u32 flags;
+	struct list_head *queue;
+
+	flags = be32_to_cpu(unlock->flags);
+
+	if (flags & LKM_GET_LVB) {
+		mlog(ML_ERROR, "bad args!  GET_LVB specified on unlock!\n");
+		return DLM_BADARGS;
+	}
+
+	if ((flags & (LKM_PUT_LVB|LKM_CANCEL)) == (LKM_PUT_LVB|LKM_CANCEL)) {
+		mlog(ML_ERROR, "bad args!  cannot modify lvb on a CANCEL "
+		     "request!\n");
+		return DLM_BADARGS;
+	}
+
+	if (unlock->namelen > DLM_LOCKID_NAME_MAX) {
+		mlog(ML_ERROR, "Invalid name length in unlock handler!\n");
+		return DLM_IVBUFLEN;
+	}
+
+	if (!dlm_grab(dlm))
+		return DLM_FORWARD;
+
+	mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
+			"Domain %s not fully joined!\n", dlm->name);
+
+	mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" : "none");
+
+	res = dlm_lookup_lockres(dlm, unlock->name, unlock->namelen);
+	if (!res) {
+		/* We assume here that a no lock resource simply means
+		 * it was migrated away and destroyed before the other
+		 * node could detect it. */
+		mlog(0, "returning DLM_FORWARD -- res no longer exists\n");
+		status = DLM_FORWARD;
+		goto not_found;
+	}
+
+	queue=&res->granted;
+	spin_lock(&res->spinlock);
+	if (res->state & DLM_LOCK_RES_RECOVERING) {
+		spin_unlock(&res->spinlock);
+		mlog(0, "returning DLM_RECOVERING\n");
+		status = DLM_RECOVERING;
+		goto leave;
+	}
+
+	if (res->state & DLM_LOCK_RES_MIGRATING) {
+		spin_unlock(&res->spinlock);
+		mlog(0, "returning DLM_MIGRATING\n");
+		status = DLM_MIGRATING;
+		goto leave;
+	}
+
+	if (res->owner != dlm->node_num) {
+		spin_unlock(&res->spinlock);
+		mlog(0, "returning DLM_FORWARD -- not master\n");
+		status = DLM_FORWARD;
+		goto leave;
+	}
+
+	for (i=0; i<3; i++) {
+		list_for_each_entry(iter, queue, list) {
+			if (iter->ml.cookie == unlock->cookie &&
+			    iter->ml.node == unlock->node_idx) {
+				dlm_lock_get(iter);
+				lock = iter;
+				break;
+			}
+		}
+		if (lock)
+			break;
+		/* scan granted -> converting -> blocked queues */
+		queue++;
+	}
+	spin_unlock(&res->spinlock);
+	if (!lock) {
+		status = DLM_IVLOCKID;
+		goto not_found;
+	}
+
+	/* lock was found on queue */
+	lksb = lock->lksb;
+	if (flags & (LKM_VALBLK|LKM_PUT_LVB) &&
+	    lock->ml.type != LKM_EXMODE)
+		flags &= ~(LKM_VALBLK|LKM_PUT_LVB);
+
+	/* unlockast only called on originating node */
+	if (flags & LKM_PUT_LVB) {
+		lksb->flags |= DLM_LKSB_PUT_LVB;
+		memcpy(&lksb->lvb[0], &unlock->lvb[0], DLM_LVB_LEN);
+	}
+
+	/* if this is in-progress, propagate the DLM_FORWARD
+	 * all the way back out */
+	status = dlmunlock_master(dlm, res, lock, lksb, flags, &ignore);
+	if (status == DLM_FORWARD)
+		mlog(0, "lockres is in progress\n");
+
+	if (flags & LKM_PUT_LVB)
+		lksb->flags &= ~DLM_LKSB_PUT_LVB;
+
+	dlm_lockres_calc_usage(dlm, res);
+	dlm_kick_thread(dlm, res);
+
+not_found:
+	if (!lock)
+		mlog(ML_ERROR, "failed to find lock to unlock! "
+			       "cookie=%u:%llu\n",
+		     dlm_get_lock_cookie_node(be64_to_cpu(unlock->cookie)),
+		     dlm_get_lock_cookie_seq(be64_to_cpu(unlock->cookie)));
+	else
+		dlm_lock_put(lock);
+
+leave:
+	if (res)
+		dlm_lockres_put(res);
+
+	dlm_put(dlm);
+
+	return status;
+}
+
+
+static enum dlm_status dlm_get_cancel_actions(struct dlm_ctxt *dlm,
+					      struct dlm_lock_resource *res,
+					      struct dlm_lock *lock,
+					      struct dlm_lockstatus *lksb,
+					      int *actions)
+{
+	enum dlm_status status;
+
+	if (dlm_lock_on_list(&res->blocked, lock)) {
+		/* cancel this outright */
+		status = DLM_NORMAL;
+		*actions = (DLM_UNLOCK_CALL_AST |
+			    DLM_UNLOCK_REMOVE_LOCK);
+	} else if (dlm_lock_on_list(&res->converting, lock)) {
+		/* cancel the request, put back on granted */
+		status = DLM_NORMAL;
+		*actions = (DLM_UNLOCK_CALL_AST |
+			    DLM_UNLOCK_REMOVE_LOCK |
+			    DLM_UNLOCK_REGRANT_LOCK |
+			    DLM_UNLOCK_CLEAR_CONVERT_TYPE);
+	} else if (dlm_lock_on_list(&res->granted, lock)) {
+		/* too late, already granted. */
+		status = DLM_CANCELGRANT;
+		*actions = DLM_UNLOCK_CALL_AST;
+	} else {
+		mlog(ML_ERROR, "lock to cancel is not on any list!\n");
+		status = DLM_IVLOCKID;
+		*actions = 0;
+	}
+	return status;
+}
+
+static enum dlm_status dlm_get_unlock_actions(struct dlm_ctxt *dlm,
+					      struct dlm_lock_resource *res,
+					      struct dlm_lock *lock,
+					      struct dlm_lockstatus *lksb,
+					      int *actions)
+{
+	enum dlm_status status;
+
+	/* unlock request */
+	if (!dlm_lock_on_list(&res->granted, lock)) {
+		status = DLM_DENIED;
+		dlm_error(status);
+		*actions = 0;
+	} else {
+		/* unlock granted lock */
+		status = DLM_NORMAL;
+		*actions = (DLM_UNLOCK_FREE_LOCK |
+			    DLM_UNLOCK_CALL_AST |
+			    DLM_UNLOCK_REMOVE_LOCK);
+	}
+	return status;
+}
+
+/* there seems to be no point in doing this async
+ * since (even for the remote case) there is really
+ * no work to queue up... so just do it and fire the
+ * unlockast by hand when done... */
+enum dlm_status dlmunlock(struct dlm_ctxt *dlm, struct dlm_lockstatus *lksb,
+			  int flags, dlm_astunlockfunc_t *unlockast, void *data)
+{
+	enum dlm_status status;
+	struct dlm_lock_resource *res;
+	struct dlm_lock *lock = NULL;
+	int call_ast, is_master;
+
+	if (!lksb) {
+		dlm_error(DLM_BADARGS);
+		return DLM_BADARGS;
+	}
+
+	if (flags & ~(LKM_CANCEL | LKM_VALBLK | LKM_INVVALBLK)) {
+		dlm_error(DLM_BADPARAM);
+		return DLM_BADPARAM;
+	}
+
+	if ((flags & (LKM_VALBLK | LKM_CANCEL)) == (LKM_VALBLK | LKM_CANCEL)) {
+		mlog(0, "VALBLK given with CANCEL: ignoring VALBLK\n");
+		flags &= ~LKM_VALBLK;
+	}
+
+	if (!lksb->lockid || !lksb->lockid->lockres) {
+		dlm_error(DLM_BADPARAM);
+		return DLM_BADPARAM;
+	}
+
+	lock = lksb->lockid;
+	BUG_ON(!lock);
+	dlm_lock_get(lock);
+
+	res = lock->lockres;
+	BUG_ON(!res);
+	dlm_lockres_get(res);
+retry:
+	call_ast = 0;
+	/* need to retry up here because owner may have changed */
+	mlog(0, "lock=%p res=%p\n", lock, res);
+
+	spin_lock(&res->spinlock);
+	is_master = (res->owner == dlm->node_num);
+	if (flags & LKM_VALBLK && lock->ml.type != LKM_EXMODE)
+		flags &= ~LKM_VALBLK;
+	spin_unlock(&res->spinlock);
+
+	if (is_master) {
+		status = dlmunlock_master(dlm, res, lock, lksb, flags,
+					  &call_ast);
+		mlog(0, "done calling dlmunlock_master: returned %d, "
+		     "call_ast is %d\n", status, call_ast);
+	} else {
+		status = dlmunlock_remote(dlm, res, lock, lksb, flags,
+					  &call_ast);
+		mlog(0, "done calling dlmunlock_remote: returned %d, "
+		     "call_ast is %d\n", status, call_ast);
+	}
+
+	if (status == DLM_RECOVERING ||
+	    status == DLM_MIGRATING ||
+	    status == DLM_FORWARD ||
+	    status == DLM_NOLOCKMGR) {
+
+		/* We want to go away for a tiny bit to allow recovery
+		 * / migration to complete on this resource. I don't
+		 * know of any wait queue we could sleep on as this
+		 * may be happening on another node. Perhaps the
+		 * proper solution is to queue up requests on the
+		 * other end? */
+
+		/* do we want to yield(); ?? */
+		msleep(50);
+
+		mlog(0, "retrying unlock due to pending recovery/"
+		     "migration/in-progress/reconnect\n");
+		goto retry;
+	}
+
+	if (call_ast) {
+		mlog(0, "calling unlockast(%p, %d)\n", data, status);
+		if (is_master) {
+			/* it is possible that there is one last bast
+			 * pending.  make sure it is flushed, then
+			 * call the unlockast.
+			 * not an issue if this is a mastered remotely,
+			 * since this lock has been removed from the
+			 * lockres queues and cannot be found. */
+			dlm_kick_thread(dlm, NULL);
+			wait_event(dlm->ast_wq,
+				   dlm_lock_basts_flushed(dlm, lock));
+		}
+		(*unlockast)(data, status);
+	}
+
+	if (status == DLM_CANCELGRANT)
+		status = DLM_NORMAL;
+
+	if (status == DLM_NORMAL) {
+		mlog(0, "kicking the thread\n");
+		dlm_kick_thread(dlm, res);
+	} else
+		dlm_error(status);
+
+	dlm_lockres_calc_usage(dlm, res);
+	dlm_lockres_put(res);
+	dlm_lock_put(lock);
+
+	mlog(0, "returning status=%d!\n", status);
+	return status;
+}
+EXPORT_SYMBOL_GPL(dlmunlock);
+
diff --git a/fs/ocfs2/dlmfs/Makefile b/fs/ocfs2/dlmfs/Makefile
new file mode 100644
index 000000000..c7895f65b
--- /dev/null
+++ b/fs/ocfs2/dlmfs/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_OCFS2_FS) += ocfs2_dlmfs.o
+
+ocfs2_dlmfs-objs := userdlm.o dlmfs.o
diff --git a/fs/ocfs2/dlmfs/dlmfs.c b/fs/ocfs2/dlmfs/dlmfs.c
new file mode 100644
index 000000000..8b2020f92
--- /dev/null
+++ b/fs/ocfs2/dlmfs/dlmfs.c
@@ -0,0 +1,630 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmfs.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM. This file handles the virtual file system
+ * used for communication with userspace. Credit should go to ramfs,
+ * which was a template for the fs side of this module.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ */
+
+/* Simple VFS hooks based on: */
+/*
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/backing-dev.h>
+#include <linux/poll.h>
+
+#include <linux/uaccess.h>
+
+#include "../stackglue.h"
+#include "userdlm.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "../cluster/masklog.h"
+
+
+static const struct super_operations dlmfs_ops;
+static const struct file_operations dlmfs_file_operations;
+static const struct inode_operations dlmfs_dir_inode_operations;
+static const struct inode_operations dlmfs_root_inode_operations;
+static const struct inode_operations dlmfs_file_inode_operations;
+static struct kmem_cache *dlmfs_inode_cache;
+
+struct workqueue_struct *user_dlm_worker;
+
+
+
+/*
+ * These are the ABI capabilities of dlmfs.
+ *
+ * Over time, dlmfs has added some features that were not part of the
+ * initial ABI.  Unfortunately, some of these features are not detectable
+ * via standard usage.  For example, Linux's default poll always returns
+ * EPOLLIN, so there is no way for a caller of poll(2) to know when dlmfs
+ * added poll support.  Instead, we provide this list of new capabilities.
+ *
+ * Capabilities is a read-only attribute.  We do it as a module parameter
+ * so we can discover it whether dlmfs is built in, loaded, or even not
+ * loaded.
+ *
+ * The ABI features are local to this machine's dlmfs mount.  This is
+ * distinct from the locking protocol, which is concerned with inter-node
+ * interaction.
+ *
+ * Capabilities:
+ * - bast	: EPOLLIN against the file descriptor of a held lock
+ *		  signifies a bast fired on the lock.
+ */
+#define DLMFS_CAPABILITIES "bast stackglue"
+static int param_set_dlmfs_capabilities(const char *val,
+					const struct kernel_param *kp)
+{
+	printk(KERN_ERR "%s: readonly parameter\n", kp->name);
+	return -EINVAL;
+}
+static int param_get_dlmfs_capabilities(char *buffer,
+					const struct kernel_param *kp)
+{
+	return strlcpy(buffer, DLMFS_CAPABILITIES,
+		       strlen(DLMFS_CAPABILITIES) + 1);
+}
+module_param_call(capabilities, param_set_dlmfs_capabilities,
+		  param_get_dlmfs_capabilities, NULL, 0444);
+MODULE_PARM_DESC(capabilities, DLMFS_CAPABILITIES);
+
+
+/*
+ * decodes a set of open flags into a valid lock level and a set of flags.
+ * returns < 0 if we have invalid flags
+ * flags which mean something to us:
+ * O_RDONLY -> PRMODE level
+ * O_WRONLY -> EXMODE level
+ *
+ * O_NONBLOCK -> NOQUEUE
+ */
+static int dlmfs_decode_open_flags(int open_flags,
+				   int *level,
+				   int *flags)
+{
+	if (open_flags & (O_WRONLY|O_RDWR))
+		*level = DLM_LOCK_EX;
+	else
+		*level = DLM_LOCK_PR;
+
+	*flags = 0;
+	if (open_flags & O_NONBLOCK)
+		*flags |= DLM_LKF_NOQUEUE;
+
+	return 0;
+}
+
+static int dlmfs_file_open(struct inode *inode,
+			   struct file *file)
+{
+	int status, level, flags;
+	struct dlmfs_filp_private *fp = NULL;
+	struct dlmfs_inode_private *ip;
+
+	if (S_ISDIR(inode->i_mode))
+		BUG();
+
+	mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
+		file->f_flags);
+
+	status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
+	if (status < 0)
+		goto bail;
+
+	/* We don't want to honor O_APPEND at read/write time as it
+	 * doesn't make sense for LVB writes. */
+	file->f_flags &= ~O_APPEND;
+
+	fp = kmalloc(sizeof(*fp), GFP_NOFS);
+	if (!fp) {
+		status = -ENOMEM;
+		goto bail;
+	}
+	fp->fp_lock_level = level;
+
+	ip = DLMFS_I(inode);
+
+	status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
+	if (status < 0) {
+		/* this is a strange error to return here but I want
+		 * to be able userspace to be able to distinguish a
+		 * valid lock request from one that simply couldn't be
+		 * granted. */
+		if (flags & DLM_LKF_NOQUEUE && status == -EAGAIN)
+			status = -ETXTBSY;
+		kfree(fp);
+		goto bail;
+	}
+
+	file->private_data = fp;
+bail:
+	return status;
+}
+
+static int dlmfs_file_release(struct inode *inode,
+			      struct file *file)
+{
+	int level;
+	struct dlmfs_inode_private *ip = DLMFS_I(inode);
+	struct dlmfs_filp_private *fp = file->private_data;
+
+	if (S_ISDIR(inode->i_mode))
+		BUG();
+
+	mlog(0, "close called on inode %lu\n", inode->i_ino);
+
+	if (fp) {
+		level = fp->fp_lock_level;
+		if (level != DLM_LOCK_IV)
+			user_dlm_cluster_unlock(&ip->ip_lockres, level);
+
+		kfree(fp);
+		file->private_data = NULL;
+	}
+
+	return 0;
+}
+
+/*
+ * We do ->setattr() just to override size changes.  Our size is the size
+ * of the LVB and nothing else.
+ */
+static int dlmfs_file_setattr(struct user_namespace *mnt_userns,
+			      struct dentry *dentry, struct iattr *attr)
+{
+	int error;
+	struct inode *inode = d_inode(dentry);
+
+	attr->ia_valid &= ~ATTR_SIZE;
+	error = setattr_prepare(&init_user_ns, dentry, attr);
+	if (error)
+		return error;
+
+	setattr_copy(&init_user_ns, inode, attr);
+	mark_inode_dirty(inode);
+	return 0;
+}
+
+static __poll_t dlmfs_file_poll(struct file *file, poll_table *wait)
+{
+	__poll_t event = 0;
+	struct inode *inode = file_inode(file);
+	struct dlmfs_inode_private *ip = DLMFS_I(inode);
+
+	poll_wait(file, &ip->ip_lockres.l_event, wait);
+
+	spin_lock(&ip->ip_lockres.l_lock);
+	if (ip->ip_lockres.l_flags & USER_LOCK_BLOCKED)
+		event = EPOLLIN | EPOLLRDNORM;
+	spin_unlock(&ip->ip_lockres.l_lock);
+
+	return event;
+}
+
+static ssize_t dlmfs_file_read(struct file *file,
+			       char __user *buf,
+			       size_t count,
+			       loff_t *ppos)
+{
+	char lvb[DLM_LVB_LEN];
+
+	if (!user_dlm_read_lvb(file_inode(file), lvb))
+		return 0;
+
+	return simple_read_from_buffer(buf, count, ppos, lvb, sizeof(lvb));
+}
+
+static ssize_t dlmfs_file_write(struct file *filp,
+				const char __user *buf,
+				size_t count,
+				loff_t *ppos)
+{
+	char lvb_buf[DLM_LVB_LEN];
+	int bytes_left;
+	struct inode *inode = file_inode(filp);
+
+	mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
+		inode->i_ino, count, *ppos);
+
+	if (*ppos >= DLM_LVB_LEN)
+		return -ENOSPC;
+
+	/* don't write past the lvb */
+	if (count > DLM_LVB_LEN - *ppos)
+		count = DLM_LVB_LEN - *ppos;
+
+	if (!count)
+		return 0;
+
+	bytes_left = copy_from_user(lvb_buf, buf, count);
+	count -= bytes_left;
+	if (count)
+		user_dlm_write_lvb(inode, lvb_buf, count);
+
+	*ppos = *ppos + count;
+	mlog(0, "wrote %zu bytes\n", count);
+	return count;
+}
+
+static void dlmfs_init_once(void *foo)
+{
+	struct dlmfs_inode_private *ip =
+		(struct dlmfs_inode_private *) foo;
+
+	ip->ip_conn = NULL;
+	ip->ip_parent = NULL;
+
+	inode_init_once(&ip->ip_vfs_inode);
+}
+
+static struct inode *dlmfs_alloc_inode(struct super_block *sb)
+{
+	struct dlmfs_inode_private *ip;
+
+	ip = alloc_inode_sb(sb, dlmfs_inode_cache, GFP_NOFS);
+	if (!ip)
+		return NULL;
+
+	return &ip->ip_vfs_inode;
+}
+
+static void dlmfs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
+}
+
+static void dlmfs_evict_inode(struct inode *inode)
+{
+	int status;
+	struct dlmfs_inode_private *ip;
+	struct user_lock_res *lockres;
+	int teardown;
+
+	clear_inode(inode);
+
+	mlog(0, "inode %lu\n", inode->i_ino);
+
+	ip = DLMFS_I(inode);
+	lockres = &ip->ip_lockres;
+
+	if (S_ISREG(inode->i_mode)) {
+		spin_lock(&lockres->l_lock);
+		teardown = !!(lockres->l_flags & USER_LOCK_IN_TEARDOWN);
+		spin_unlock(&lockres->l_lock);
+		if (!teardown) {
+			status = user_dlm_destroy_lock(lockres);
+			if (status < 0)
+				mlog_errno(status);
+		}
+		iput(ip->ip_parent);
+		goto clear_fields;
+	}
+
+	mlog(0, "we're a directory, ip->ip_conn = 0x%p\n", ip->ip_conn);
+	/* we must be a directory. If required, lets unregister the
+	 * dlm context now. */
+	if (ip->ip_conn)
+		user_dlm_unregister(ip->ip_conn);
+clear_fields:
+	ip->ip_parent = NULL;
+	ip->ip_conn = NULL;
+}
+
+static struct inode *dlmfs_get_root_inode(struct super_block *sb)
+{
+	struct inode *inode = new_inode(sb);
+	umode_t mode = S_IFDIR | 0755;
+
+	if (inode) {
+		inode->i_ino = get_next_ino();
+		inode_init_owner(&init_user_ns, inode, NULL, mode);
+		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+		inc_nlink(inode);
+
+		inode->i_fop = &simple_dir_operations;
+		inode->i_op = &dlmfs_root_inode_operations;
+	}
+
+	return inode;
+}
+
+static struct inode *dlmfs_get_inode(struct inode *parent,
+				     struct dentry *dentry,
+				     umode_t mode)
+{
+	struct super_block *sb = parent->i_sb;
+	struct inode * inode = new_inode(sb);
+	struct dlmfs_inode_private *ip;
+
+	if (!inode)
+		return NULL;
+
+	inode->i_ino = get_next_ino();
+	inode_init_owner(&init_user_ns, inode, parent, mode);
+	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
+
+	ip = DLMFS_I(inode);
+	ip->ip_conn = DLMFS_I(parent)->ip_conn;
+
+	switch (mode & S_IFMT) {
+	default:
+		/* for now we don't support anything other than
+		 * directories and regular files. */
+		BUG();
+		break;
+	case S_IFREG:
+		inode->i_op = &dlmfs_file_inode_operations;
+		inode->i_fop = &dlmfs_file_operations;
+
+		i_size_write(inode,  DLM_LVB_LEN);
+
+		user_dlm_lock_res_init(&ip->ip_lockres, dentry);
+
+		/* released at clear_inode time, this insures that we
+		 * get to drop the dlm reference on each lock *before*
+		 * we call the unregister code for releasing parent
+		 * directories. */
+		ip->ip_parent = igrab(parent);
+		BUG_ON(!ip->ip_parent);
+		break;
+	case S_IFDIR:
+		inode->i_op = &dlmfs_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+
+		/* directory inodes start off with i_nlink ==
+		 * 2 (for "." entry) */
+		inc_nlink(inode);
+		break;
+	}
+	return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int dlmfs_mkdir(struct user_namespace * mnt_userns,
+		       struct inode * dir,
+		       struct dentry * dentry,
+		       umode_t mode)
+{
+	int status;
+	struct inode *inode = NULL;
+	const struct qstr *domain = &dentry->d_name;
+	struct dlmfs_inode_private *ip;
+	struct ocfs2_cluster_connection *conn;
+
+	mlog(0, "mkdir %.*s\n", domain->len, domain->name);
+
+	/* verify that we have a proper domain */
+	if (domain->len >= GROUP_NAME_MAX) {
+		status = -EINVAL;
+		mlog(ML_ERROR, "invalid domain name for directory.\n");
+		goto bail;
+	}
+
+	inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
+	if (!inode) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	ip = DLMFS_I(inode);
+
+	conn = user_dlm_register(domain);
+	if (IS_ERR(conn)) {
+		status = PTR_ERR(conn);
+		mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
+		     status, domain->len, domain->name);
+		goto bail;
+	}
+	ip->ip_conn = conn;
+
+	inc_nlink(dir);
+	d_instantiate(dentry, inode);
+	dget(dentry);	/* Extra count - pin the dentry in core */
+
+	status = 0;
+bail:
+	if (status < 0)
+		iput(inode);
+	return status;
+}
+
+static int dlmfs_create(struct user_namespace *mnt_userns,
+			struct inode *dir,
+			struct dentry *dentry,
+			umode_t mode,
+			bool excl)
+{
+	int status = 0;
+	struct inode *inode;
+	const struct qstr *name = &dentry->d_name;
+
+	mlog(0, "create %.*s\n", name->len, name->name);
+
+	/* verify name is valid and doesn't contain any dlm reserved
+	 * characters */
+	if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
+	    name->name[0] == '$') {
+		status = -EINVAL;
+		mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
+		     name->name);
+		goto bail;
+	}
+
+	inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
+	if (!inode) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	d_instantiate(dentry, inode);
+	dget(dentry);	/* Extra count - pin the dentry in core */
+bail:
+	return status;
+}
+
+static int dlmfs_unlink(struct inode *dir,
+			struct dentry *dentry)
+{
+	int status;
+	struct inode *inode = d_inode(dentry);
+
+	mlog(0, "unlink inode %lu\n", inode->i_ino);
+
+	/* if there are no current holders, or none that are waiting
+	 * to acquire a lock, this basically destroys our lockres. */
+	status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
+	if (status < 0) {
+		mlog(ML_ERROR, "unlink %pd, error %d from destroy\n",
+		     dentry, status);
+		goto bail;
+	}
+	status = simple_unlink(dir, dentry);
+bail:
+	return status;
+}
+
+static int dlmfs_fill_super(struct super_block * sb,
+			    void * data,
+			    int silent)
+{
+	sb->s_maxbytes = MAX_LFS_FILESIZE;
+	sb->s_blocksize = PAGE_SIZE;
+	sb->s_blocksize_bits = PAGE_SHIFT;
+	sb->s_magic = DLMFS_MAGIC;
+	sb->s_op = &dlmfs_ops;
+	sb->s_root = d_make_root(dlmfs_get_root_inode(sb));
+	if (!sb->s_root)
+		return -ENOMEM;
+	return 0;
+}
+
+static const struct file_operations dlmfs_file_operations = {
+	.open		= dlmfs_file_open,
+	.release	= dlmfs_file_release,
+	.poll		= dlmfs_file_poll,
+	.read		= dlmfs_file_read,
+	.write		= dlmfs_file_write,
+	.llseek		= default_llseek,
+};
+
+static const struct inode_operations dlmfs_dir_inode_operations = {
+	.create		= dlmfs_create,
+	.lookup		= simple_lookup,
+	.unlink		= dlmfs_unlink,
+};
+
+/* this way we can restrict mkdir to only the toplevel of the fs. */
+static const struct inode_operations dlmfs_root_inode_operations = {
+	.lookup		= simple_lookup,
+	.mkdir		= dlmfs_mkdir,
+	.rmdir		= simple_rmdir,
+};
+
+static const struct super_operations dlmfs_ops = {
+	.statfs		= simple_statfs,
+	.alloc_inode	= dlmfs_alloc_inode,
+	.free_inode	= dlmfs_free_inode,
+	.evict_inode	= dlmfs_evict_inode,
+	.drop_inode	= generic_delete_inode,
+};
+
+static const struct inode_operations dlmfs_file_inode_operations = {
+	.getattr	= simple_getattr,
+	.setattr	= dlmfs_file_setattr,
+};
+
+static struct dentry *dlmfs_mount(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return mount_nodev(fs_type, flags, data, dlmfs_fill_super);
+}
+
+static struct file_system_type dlmfs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "ocfs2_dlmfs",
+	.mount		= dlmfs_mount,
+	.kill_sb	= kill_litter_super,
+};
+MODULE_ALIAS_FS("ocfs2_dlmfs");
+
+static int __init init_dlmfs_fs(void)
+{
+	int status;
+	int cleanup_inode = 0, cleanup_worker = 0;
+
+	dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
+				sizeof(struct dlmfs_inode_private),
+				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
+					SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+				dlmfs_init_once);
+	if (!dlmfs_inode_cache) {
+		status = -ENOMEM;
+		goto bail;
+	}
+	cleanup_inode = 1;
+
+	user_dlm_worker = alloc_workqueue("user_dlm", WQ_MEM_RECLAIM, 0);
+	if (!user_dlm_worker) {
+		status = -ENOMEM;
+		goto bail;
+	}
+	cleanup_worker = 1;
+
+	user_dlm_set_locking_protocol();
+	status = register_filesystem(&dlmfs_fs_type);
+bail:
+	if (status) {
+		if (cleanup_inode)
+			kmem_cache_destroy(dlmfs_inode_cache);
+		if (cleanup_worker)
+			destroy_workqueue(user_dlm_worker);
+	} else
+		printk("OCFS2 User DLM kernel interface loaded\n");
+	return status;
+}
+
+static void __exit exit_dlmfs_fs(void)
+{
+	unregister_filesystem(&dlmfs_fs_type);
+
+	destroy_workqueue(user_dlm_worker);
+
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(dlmfs_inode_cache);
+
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("OCFS2 DLM-Filesystem");
+
+module_init(init_dlmfs_fs)
+module_exit(exit_dlmfs_fs)
diff --git a/fs/ocfs2/dlmfs/userdlm.c b/fs/ocfs2/dlmfs/userdlm.c
new file mode 100644
index 000000000..617c92e7b
--- /dev/null
+++ b/fs/ocfs2/dlmfs/userdlm.c
@@ -0,0 +1,682 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * userdlm.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM.
+ *
+ * Many of the functions here are pared down versions of dlmglue.c
+ * functions.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched/signal.h>
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/crc32.h>
+
+#include "../ocfs2_lockingver.h"
+#include "../stackglue.h"
+#include "userdlm.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "../cluster/masklog.h"
+
+
+static inline struct user_lock_res *user_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
+{
+	return container_of(lksb, struct user_lock_res, l_lksb);
+}
+
+static inline int user_check_wait_flag(struct user_lock_res *lockres,
+				       int flag)
+{
+	int ret;
+
+	spin_lock(&lockres->l_lock);
+	ret = lockres->l_flags & flag;
+	spin_unlock(&lockres->l_lock);
+
+	return ret;
+}
+
+static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !user_check_wait_flag(lockres, USER_LOCK_BUSY));
+}
+
+static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
+}
+
+/* I heart container_of... */
+static inline struct ocfs2_cluster_connection *
+cluster_connection_from_user_lockres(struct user_lock_res *lockres)
+{
+	struct dlmfs_inode_private *ip;
+
+	ip = container_of(lockres,
+			  struct dlmfs_inode_private,
+			  ip_lockres);
+	return ip->ip_conn;
+}
+
+static struct inode *
+user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
+{
+	struct dlmfs_inode_private *ip;
+
+	ip = container_of(lockres,
+			  struct dlmfs_inode_private,
+			  ip_lockres);
+	return &ip->ip_vfs_inode;
+}
+
+static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
+{
+	spin_lock(&lockres->l_lock);
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+	spin_unlock(&lockres->l_lock);
+}
+
+#define user_log_dlm_error(_func, _stat, _lockres) do {			\
+	mlog(ML_ERROR, "Dlm error %d while calling %s on "		\
+		"resource %.*s\n", _stat, _func,			\
+		_lockres->l_namelen, _lockres->l_name); 		\
+} while (0)
+
+/* WARNING: This function lives in a world where the only three lock
+ * levels are EX, PR, and NL. It *will* have to be adjusted when more
+ * lock types are added. */
+static inline int user_highest_compat_lock_level(int level)
+{
+	int new_level = DLM_LOCK_EX;
+
+	if (level == DLM_LOCK_EX)
+		new_level = DLM_LOCK_NL;
+	else if (level == DLM_LOCK_PR)
+		new_level = DLM_LOCK_PR;
+	return new_level;
+}
+
+static void user_ast(struct ocfs2_dlm_lksb *lksb)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+	int status;
+
+	mlog(ML_BASTS, "AST fired for lockres %.*s, level %d => %d\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_level,
+	     lockres->l_requested);
+
+	spin_lock(&lockres->l_lock);
+
+	status = ocfs2_dlm_lock_status(&lockres->l_lksb);
+	if (status) {
+		mlog(ML_ERROR, "lksb status value of %u on lockres %.*s\n",
+		     status, lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		return;
+	}
+
+	mlog_bug_on_msg(lockres->l_requested == DLM_LOCK_IV,
+			"Lockres %.*s, requested ivmode. flags 0x%x\n",
+			lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	/* we're downconverting. */
+	if (lockres->l_requested < lockres->l_level) {
+		if (lockres->l_requested <=
+		    user_highest_compat_lock_level(lockres->l_blocking)) {
+			lockres->l_blocking = DLM_LOCK_NL;
+			lockres->l_flags &= ~USER_LOCK_BLOCKED;
+		}
+	}
+
+	lockres->l_level = lockres->l_requested;
+	lockres->l_requested = DLM_LOCK_IV;
+	lockres->l_flags |= USER_LOCK_ATTACHED;
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
+{
+	struct inode *inode;
+	inode = user_dlm_inode_from_user_lockres(lockres);
+	if (!igrab(inode))
+		BUG();
+}
+
+static void user_dlm_unblock_lock(struct work_struct *work);
+
+static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
+{
+	if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
+		user_dlm_grab_inode_ref(lockres);
+
+		INIT_WORK(&lockres->l_work, user_dlm_unblock_lock);
+
+		queue_work(user_dlm_worker, &lockres->l_work);
+		lockres->l_flags |= USER_LOCK_QUEUED;
+	}
+}
+
+static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
+{
+	int queue = 0;
+
+	if (!(lockres->l_flags & USER_LOCK_BLOCKED))
+		return;
+
+	switch (lockres->l_blocking) {
+	case DLM_LOCK_EX:
+		if (!lockres->l_ex_holders && !lockres->l_ro_holders)
+			queue = 1;
+		break;
+	case DLM_LOCK_PR:
+		if (!lockres->l_ex_holders)
+			queue = 1;
+		break;
+	default:
+		BUG();
+	}
+
+	if (queue)
+		__user_dlm_queue_lockres(lockres);
+}
+
+static void user_bast(struct ocfs2_dlm_lksb *lksb, int level)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+
+	mlog(ML_BASTS, "BAST fired for lockres %.*s, blocking %d, level %d\n",
+	     lockres->l_namelen, lockres->l_name, level, lockres->l_level);
+
+	spin_lock(&lockres->l_lock);
+	lockres->l_flags |= USER_LOCK_BLOCKED;
+	if (level > lockres->l_blocking)
+		lockres->l_blocking = level;
+
+	__user_dlm_queue_lockres(lockres);
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+static void user_unlock_ast(struct ocfs2_dlm_lksb *lksb, int status)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+
+	mlog(ML_BASTS, "UNLOCK AST fired for lockres %.*s, flags 0x%x\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	if (status)
+		mlog(ML_ERROR, "dlm returns status %d\n", status);
+
+	spin_lock(&lockres->l_lock);
+	/* The teardown flag gets set early during the unlock process,
+	 * so test the cancel flag to make sure that this ast isn't
+	 * for a concurrent cancel. */
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
+	    && !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
+		lockres->l_level = DLM_LOCK_IV;
+	} else if (status == DLM_CANCELGRANT) {
+		/* We tried to cancel a convert request, but it was
+		 * already granted. Don't clear the busy flag - the
+		 * ast should've done this already. */
+		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
+		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+		goto out_noclear;
+	} else {
+		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
+		/* Cancel succeeded, we want to re-queue */
+		lockres->l_requested = DLM_LOCK_IV; /* cancel an
+						    * upconvert
+						    * request. */
+		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+		/* we want the unblock thread to look at it again
+		 * now. */
+		if (lockres->l_flags & USER_LOCK_BLOCKED)
+			__user_dlm_queue_lockres(lockres);
+	}
+
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+out_noclear:
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+/*
+ * This is the userdlmfs locking protocol version.
+ *
+ * See fs/ocfs2/dlmglue.c for more details on locking versions.
+ */
+static struct ocfs2_locking_protocol user_dlm_lproto = {
+	.lp_max_version = {
+		.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+		.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+	},
+	.lp_lock_ast		= user_ast,
+	.lp_blocking_ast	= user_bast,
+	.lp_unlock_ast		= user_unlock_ast,
+};
+
+static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
+{
+	struct inode *inode;
+	inode = user_dlm_inode_from_user_lockres(lockres);
+	iput(inode);
+}
+
+static void user_dlm_unblock_lock(struct work_struct *work)
+{
+	int new_level, status;
+	struct user_lock_res *lockres =
+		container_of(work, struct user_lock_res, l_work);
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	mlog(0, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
+
+	spin_lock(&lockres->l_lock);
+
+	mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
+			"Lockres %.*s, flags 0x%x\n",
+			lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	/* notice that we don't clear USER_LOCK_BLOCKED here. If it's
+	 * set, we want user_ast clear it. */
+	lockres->l_flags &= ~USER_LOCK_QUEUED;
+
+	/* It's valid to get here and no longer be blocked - if we get
+	 * several basts in a row, we might be queued by the first
+	 * one, the unblock thread might run and clear the queued
+	 * flag, and finally we might get another bast which re-queues
+	 * us before our ast for the downconvert is called. */
+	if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
+		mlog(ML_BASTS, "lockres %.*s USER_LOCK_BLOCKED\n",
+		     lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		goto drop_ref;
+	}
+
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_TEARDOWN\n",
+		     lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		goto drop_ref;
+	}
+
+	if (lockres->l_flags & USER_LOCK_BUSY) {
+		if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
+			mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_CANCEL\n",
+			     lockres->l_namelen, lockres->l_name);
+			spin_unlock(&lockres->l_lock);
+			goto drop_ref;
+		}
+
+		lockres->l_flags |= USER_LOCK_IN_CANCEL;
+		spin_unlock(&lockres->l_lock);
+
+		status = ocfs2_dlm_unlock(conn, &lockres->l_lksb,
+					  DLM_LKF_CANCEL);
+		if (status)
+			user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
+		goto drop_ref;
+	}
+
+	/* If there are still incompat holders, we can exit safely
+	 * without worrying about re-queueing this lock as that will
+	 * happen on the last call to user_cluster_unlock. */
+	if ((lockres->l_blocking == DLM_LOCK_EX)
+	    && (lockres->l_ex_holders || lockres->l_ro_holders)) {
+		spin_unlock(&lockres->l_lock);
+		mlog(ML_BASTS, "lockres %.*s, EX/PR Holders %u,%u\n",
+		     lockres->l_namelen, lockres->l_name,
+		     lockres->l_ex_holders, lockres->l_ro_holders);
+		goto drop_ref;
+	}
+
+	if ((lockres->l_blocking == DLM_LOCK_PR)
+	    && lockres->l_ex_holders) {
+		spin_unlock(&lockres->l_lock);
+		mlog(ML_BASTS, "lockres %.*s, EX Holders %u\n",
+		     lockres->l_namelen, lockres->l_name,
+		     lockres->l_ex_holders);
+		goto drop_ref;
+	}
+
+	/* yay, we can downconvert now. */
+	new_level = user_highest_compat_lock_level(lockres->l_blocking);
+	lockres->l_requested = new_level;
+	lockres->l_flags |= USER_LOCK_BUSY;
+	mlog(ML_BASTS, "lockres %.*s, downconvert %d => %d\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_level, new_level);
+	spin_unlock(&lockres->l_lock);
+
+	/* need lock downconvert request now... */
+	status = ocfs2_dlm_lock(conn, new_level, &lockres->l_lksb,
+				DLM_LKF_CONVERT|DLM_LKF_VALBLK,
+				lockres->l_name,
+				lockres->l_namelen);
+	if (status) {
+		user_log_dlm_error("ocfs2_dlm_lock", status, lockres);
+		user_recover_from_dlm_error(lockres);
+	}
+
+drop_ref:
+	user_dlm_drop_inode_ref(lockres);
+}
+
+static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
+					int level)
+{
+	switch(level) {
+	case DLM_LOCK_EX:
+		lockres->l_ex_holders++;
+		break;
+	case DLM_LOCK_PR:
+		lockres->l_ro_holders++;
+		break;
+	default:
+		BUG();
+	}
+}
+
+/* predict what lock level we'll be dropping down to on behalf
+ * of another node, and return true if the currently wanted
+ * level will be compatible with it. */
+static inline int
+user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
+				  int wanted)
+{
+	BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
+
+	return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
+}
+
+int user_dlm_cluster_lock(struct user_lock_res *lockres,
+			  int level,
+			  int lkm_flags)
+{
+	int status, local_flags;
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	if (level != DLM_LOCK_EX &&
+	    level != DLM_LOCK_PR) {
+		mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
+		     lockres->l_namelen, lockres->l_name);
+		status = -EINVAL;
+		goto bail;
+	}
+
+	mlog(ML_BASTS, "lockres %.*s, level %d, flags = 0x%x\n",
+	     lockres->l_namelen, lockres->l_name, level, lkm_flags);
+
+again:
+	if (signal_pending(current)) {
+		status = -ERESTARTSYS;
+		goto bail;
+	}
+
+	spin_lock(&lockres->l_lock);
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		spin_unlock(&lockres->l_lock);
+		status = -EAGAIN;
+		goto bail;
+	}
+
+	/* We only compare against the currently granted level
+	 * here. If the lock is blocked waiting on a downconvert,
+	 * we'll get caught below. */
+	if ((lockres->l_flags & USER_LOCK_BUSY) &&
+	    (level > lockres->l_level)) {
+		/* is someone sitting in dlm_lock? If so, wait on
+		 * them. */
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_busy_lock(lockres);
+		goto again;
+	}
+
+	if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
+	    (!user_may_continue_on_blocked_lock(lockres, level))) {
+		/* is the lock is currently blocked on behalf of
+		 * another node */
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_blocked_lock(lockres);
+		goto again;
+	}
+
+	if (level > lockres->l_level) {
+		local_flags = lkm_flags | DLM_LKF_VALBLK;
+		if (lockres->l_level != DLM_LOCK_IV)
+			local_flags |= DLM_LKF_CONVERT;
+
+		lockres->l_requested = level;
+		lockres->l_flags |= USER_LOCK_BUSY;
+		spin_unlock(&lockres->l_lock);
+
+		BUG_ON(level == DLM_LOCK_IV);
+		BUG_ON(level == DLM_LOCK_NL);
+
+		/* call dlm_lock to upgrade lock now */
+		status = ocfs2_dlm_lock(conn, level, &lockres->l_lksb,
+					local_flags, lockres->l_name,
+					lockres->l_namelen);
+		if (status) {
+			if ((lkm_flags & DLM_LKF_NOQUEUE) &&
+			    (status != -EAGAIN))
+				user_log_dlm_error("ocfs2_dlm_lock",
+						   status, lockres);
+			user_recover_from_dlm_error(lockres);
+			goto bail;
+		}
+
+		user_wait_on_busy_lock(lockres);
+		goto again;
+	}
+
+	user_dlm_inc_holders(lockres, level);
+	spin_unlock(&lockres->l_lock);
+
+	status = 0;
+bail:
+	return status;
+}
+
+static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
+					int level)
+{
+	switch(level) {
+	case DLM_LOCK_EX:
+		BUG_ON(!lockres->l_ex_holders);
+		lockres->l_ex_holders--;
+		break;
+	case DLM_LOCK_PR:
+		BUG_ON(!lockres->l_ro_holders);
+		lockres->l_ro_holders--;
+		break;
+	default:
+		BUG();
+	}
+}
+
+void user_dlm_cluster_unlock(struct user_lock_res *lockres,
+			     int level)
+{
+	if (level != DLM_LOCK_EX &&
+	    level != DLM_LOCK_PR) {
+		mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
+		     lockres->l_namelen, lockres->l_name);
+		return;
+	}
+
+	spin_lock(&lockres->l_lock);
+	user_dlm_dec_holders(lockres, level);
+	__user_dlm_cond_queue_lockres(lockres);
+	spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_write_lvb(struct inode *inode,
+			const char *val,
+			unsigned int len)
+{
+	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+	char *lvb;
+
+	BUG_ON(len > DLM_LVB_LEN);
+
+	spin_lock(&lockres->l_lock);
+
+	BUG_ON(lockres->l_level < DLM_LOCK_EX);
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	memcpy(lvb, val, len);
+
+	spin_unlock(&lockres->l_lock);
+}
+
+bool user_dlm_read_lvb(struct inode *inode, char *val)
+{
+	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+	char *lvb;
+	bool ret = true;
+
+	spin_lock(&lockres->l_lock);
+
+	BUG_ON(lockres->l_level < DLM_LOCK_PR);
+	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)) {
+		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+		memcpy(val, lvb, DLM_LVB_LEN);
+	} else
+		ret = false;
+
+	spin_unlock(&lockres->l_lock);
+	return ret;
+}
+
+void user_dlm_lock_res_init(struct user_lock_res *lockres,
+			    struct dentry *dentry)
+{
+	memset(lockres, 0, sizeof(*lockres));
+
+	spin_lock_init(&lockres->l_lock);
+	init_waitqueue_head(&lockres->l_event);
+	lockres->l_level = DLM_LOCK_IV;
+	lockres->l_requested = DLM_LOCK_IV;
+	lockres->l_blocking = DLM_LOCK_IV;
+
+	/* should have been checked before getting here. */
+	BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
+
+	memcpy(lockres->l_name,
+	       dentry->d_name.name,
+	       dentry->d_name.len);
+	lockres->l_namelen = dentry->d_name.len;
+}
+
+int user_dlm_destroy_lock(struct user_lock_res *lockres)
+{
+	int status = -EBUSY;
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	mlog(ML_BASTS, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
+
+	spin_lock(&lockres->l_lock);
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
+
+	while (lockres->l_flags & USER_LOCK_BUSY) {
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_busy_lock(lockres);
+
+		spin_lock(&lockres->l_lock);
+	}
+
+	if (lockres->l_ro_holders || lockres->l_ex_holders) {
+		lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	status = 0;
+	if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
+		/*
+		 * lock is never requested, leave USER_LOCK_IN_TEARDOWN set
+		 * to avoid new lock request coming in.
+		 */
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	lockres->l_flags |= USER_LOCK_BUSY;
+	spin_unlock(&lockres->l_lock);
+
+	status = ocfs2_dlm_unlock(conn, &lockres->l_lksb, DLM_LKF_VALBLK);
+	if (status) {
+		spin_lock(&lockres->l_lock);
+		lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
+		lockres->l_flags &= ~USER_LOCK_BUSY;
+		spin_unlock(&lockres->l_lock);
+		user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
+		goto bail;
+	}
+
+	user_wait_on_busy_lock(lockres);
+
+	status = 0;
+bail:
+	return status;
+}
+
+static void user_dlm_recovery_handler_noop(int node_num,
+					   void *recovery_data)
+{
+	/* We ignore recovery events */
+	return;
+}
+
+void user_dlm_set_locking_protocol(void)
+{
+	ocfs2_stack_glue_set_max_proto_version(&user_dlm_lproto.lp_max_version);
+}
+
+struct ocfs2_cluster_connection *user_dlm_register(const struct qstr *name)
+{
+	int rc;
+	struct ocfs2_cluster_connection *conn;
+
+	rc = ocfs2_cluster_connect_agnostic(name->name, name->len,
+					    &user_dlm_lproto,
+					    user_dlm_recovery_handler_noop,
+					    NULL, &conn);
+	if (rc)
+		mlog_errno(rc);
+
+	return rc ? ERR_PTR(rc) : conn;
+}
+
+void user_dlm_unregister(struct ocfs2_cluster_connection *conn)
+{
+	ocfs2_cluster_disconnect(conn, 0);
+}
diff --git a/fs/ocfs2/dlmfs/userdlm.h b/fs/ocfs2/dlmfs/userdlm.h
new file mode 100644
index 000000000..47ba18eac
--- /dev/null
+++ b/fs/ocfs2/dlmfs/userdlm.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * userdlm.h
+ *
+ * Userspace dlm defines
+ *
+ * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
+ */
+
+
+#ifndef USERDLM_H
+#define USERDLM_H
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+/* user_lock_res->l_flags flags. */
+#define USER_LOCK_ATTACHED      (0x00000001) /* we have initialized
+					       * the lvb */
+#define USER_LOCK_BUSY          (0x00000002) /* we are currently in
+					       * dlm_lock */
+#define USER_LOCK_BLOCKED       (0x00000004) /* blocked waiting to
+					      * downconvert*/
+#define USER_LOCK_IN_TEARDOWN   (0x00000008) /* we're currently
+					      * destroying this
+					      * lock. */
+#define USER_LOCK_QUEUED        (0x00000010) /* lock is on the
+					      * workqueue */
+#define USER_LOCK_IN_CANCEL     (0x00000020)
+
+struct user_lock_res {
+	spinlock_t               l_lock;
+
+	int                      l_flags;
+
+#define USER_DLM_LOCK_ID_MAX_LEN  32
+	char                     l_name[USER_DLM_LOCK_ID_MAX_LEN];
+	int                      l_namelen;
+	int                      l_level;
+	unsigned int             l_ro_holders;
+	unsigned int             l_ex_holders;
+	struct ocfs2_dlm_lksb    l_lksb;
+
+	int                      l_requested;
+	int                      l_blocking;
+
+	wait_queue_head_t        l_event;
+
+	struct work_struct       l_work;
+};
+
+extern struct workqueue_struct *user_dlm_worker;
+
+void user_dlm_lock_res_init(struct user_lock_res *lockres,
+			    struct dentry *dentry);
+int user_dlm_destroy_lock(struct user_lock_res *lockres);
+int user_dlm_cluster_lock(struct user_lock_res *lockres,
+			  int level,
+			  int lkm_flags);
+void user_dlm_cluster_unlock(struct user_lock_res *lockres,
+			     int level);
+void user_dlm_write_lvb(struct inode *inode,
+			const char *val,
+			unsigned int len);
+bool user_dlm_read_lvb(struct inode *inode, char *val);
+struct ocfs2_cluster_connection *user_dlm_register(const struct qstr *name);
+void user_dlm_unregister(struct ocfs2_cluster_connection *conn);
+void user_dlm_set_locking_protocol(void);
+
+struct dlmfs_inode_private {
+	struct ocfs2_cluster_connection	*ip_conn;
+
+	struct user_lock_res ip_lockres; /* unused for directories. */
+	struct inode         *ip_parent;
+
+	struct inode         ip_vfs_inode;
+};
+
+static inline struct dlmfs_inode_private *
+DLMFS_I(struct inode *inode)
+{
+        return container_of(inode,
+			    struct dlmfs_inode_private,
+			    ip_vfs_inode);
+}
+
+struct dlmfs_filp_private {
+	int                  fp_lock_level;
+};
+
+#define DLMFS_MAGIC	0x76a9f425
+
+#endif /* USERDLM_H */
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
new file mode 100644
index 000000000..c28bc983a
--- /dev/null
+++ b/fs/ocfs2/dlmglue.c
@@ -0,0 +1,4470 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dlmglue.c
+ *
+ * Code which implements an OCFS2 specific interface to our DLM.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/kthread.h>
+#include <linux/pagemap.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/time.h>
+#include <linux/delay.h>
+#include <linux/quotaops.h>
+#include <linux/sched/signal.h>
+
+#define MLOG_MASK_PREFIX ML_DLM_GLUE
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+#include "ocfs2_lockingver.h"
+
+#include "alloc.h"
+#include "dcache.h"
+#include "dlmglue.h"
+#include "extent_map.h"
+#include "file.h"
+#include "heartbeat.h"
+#include "inode.h"
+#include "journal.h"
+#include "stackglue.h"
+#include "slot_map.h"
+#include "super.h"
+#include "uptodate.h"
+#include "quota.h"
+#include "refcounttree.h"
+#include "acl.h"
+
+#include "buffer_head_io.h"
+
+struct ocfs2_mask_waiter {
+	struct list_head	mw_item;
+	int			mw_status;
+	struct completion	mw_complete;
+	unsigned long		mw_mask;
+	unsigned long		mw_goal;
+#ifdef CONFIG_OCFS2_FS_STATS
+	ktime_t			mw_lock_start;
+#endif
+};
+
+static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres);
+static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres);
+static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres);
+static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres);
+
+/*
+ * Return value from ->downconvert_worker functions.
+ *
+ * These control the precise actions of ocfs2_unblock_lock()
+ * and ocfs2_process_blocked_lock()
+ *
+ */
+enum ocfs2_unblock_action {
+	UNBLOCK_CONTINUE	= 0, /* Continue downconvert */
+	UNBLOCK_CONTINUE_POST	= 1, /* Continue downconvert, fire
+				      * ->post_unlock callback */
+	UNBLOCK_STOP_POST	= 2, /* Do not downconvert, fire
+				      * ->post_unlock() callback. */
+};
+
+struct ocfs2_unblock_ctl {
+	int requeue;
+	enum ocfs2_unblock_action unblock_action;
+};
+
+/* Lockdep class keys */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static struct lock_class_key lockdep_keys[OCFS2_NUM_LOCK_TYPES];
+#endif
+
+static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
+					int new_level);
+static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres);
+
+static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
+				     int blocking);
+
+static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
+				       int blocking);
+
+static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
+				     struct ocfs2_lock_res *lockres);
+
+static void ocfs2_set_qinfo_lvb(struct ocfs2_lock_res *lockres);
+
+static int ocfs2_check_refcount_downconvert(struct ocfs2_lock_res *lockres,
+					    int new_level);
+static int ocfs2_refcount_convert_worker(struct ocfs2_lock_res *lockres,
+					 int blocking);
+
+#define mlog_meta_lvb(__level, __lockres) ocfs2_dump_meta_lvb_info(__level, __PRETTY_FUNCTION__, __LINE__, __lockres)
+
+/* This aids in debugging situations where a bad LVB might be involved. */
+static void ocfs2_dump_meta_lvb_info(u64 level,
+				     const char *function,
+				     unsigned int line,
+				     struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+
+	mlog(level, "LVB information for %s (called from %s:%u):\n",
+	     lockres->l_name, function, line);
+	mlog(level, "version: %u, clusters: %u, generation: 0x%x\n",
+	     lvb->lvb_version, be32_to_cpu(lvb->lvb_iclusters),
+	     be32_to_cpu(lvb->lvb_igeneration));
+	mlog(level, "size: %llu, uid %u, gid %u, mode 0x%x\n",
+	     (unsigned long long)be64_to_cpu(lvb->lvb_isize),
+	     be32_to_cpu(lvb->lvb_iuid), be32_to_cpu(lvb->lvb_igid),
+	     be16_to_cpu(lvb->lvb_imode));
+	mlog(level, "nlink %u, atime_packed 0x%llx, ctime_packed 0x%llx, "
+	     "mtime_packed 0x%llx iattr 0x%x\n", be16_to_cpu(lvb->lvb_inlink),
+	     (long long)be64_to_cpu(lvb->lvb_iatime_packed),
+	     (long long)be64_to_cpu(lvb->lvb_ictime_packed),
+	     (long long)be64_to_cpu(lvb->lvb_imtime_packed),
+	     be32_to_cpu(lvb->lvb_iattr));
+}
+
+
+/*
+ * OCFS2 Lock Resource Operations
+ *
+ * These fine tune the behavior of the generic dlmglue locking infrastructure.
+ *
+ * The most basic of lock types can point ->l_priv to their respective
+ * struct ocfs2_super and allow the default actions to manage things.
+ *
+ * Right now, each lock type also needs to implement an init function,
+ * and trivial lock/unlock wrappers. ocfs2_simple_drop_lockres()
+ * should be called when the lock is no longer needed (i.e., object
+ * destruction time).
+ */
+struct ocfs2_lock_res_ops {
+	/*
+	 * Translate an ocfs2_lock_res * into an ocfs2_super *. Define
+	 * this callback if ->l_priv is not an ocfs2_super pointer
+	 */
+	struct ocfs2_super * (*get_osb)(struct ocfs2_lock_res *);
+
+	/*
+	 * Optionally called in the downconvert thread after a
+	 * successful downconvert. The lockres will not be referenced
+	 * after this callback is called, so it is safe to free
+	 * memory, etc.
+	 *
+	 * The exact semantics of when this is called are controlled
+	 * by ->downconvert_worker()
+	 */
+	void (*post_unlock)(struct ocfs2_super *, struct ocfs2_lock_res *);
+
+	/*
+	 * Allow a lock type to add checks to determine whether it is
+	 * safe to downconvert a lock. Return 0 to re-queue the
+	 * downconvert at a later time, nonzero to continue.
+	 *
+	 * For most locks, the default checks that there are no
+	 * incompatible holders are sufficient.
+	 *
+	 * Called with the lockres spinlock held.
+	 */
+	int (*check_downconvert)(struct ocfs2_lock_res *, int);
+
+	/*
+	 * Allows a lock type to populate the lock value block. This
+	 * is called on downconvert, and when we drop a lock.
+	 *
+	 * Locks that want to use this should set LOCK_TYPE_USES_LVB
+	 * in the flags field.
+	 *
+	 * Called with the lockres spinlock held.
+	 */
+	void (*set_lvb)(struct ocfs2_lock_res *);
+
+	/*
+	 * Called from the downconvert thread when it is determined
+	 * that a lock will be downconverted. This is called without
+	 * any locks held so the function can do work that might
+	 * schedule (syncing out data, etc).
+	 *
+	 * This should return any one of the ocfs2_unblock_action
+	 * values, depending on what it wants the thread to do.
+	 */
+	int (*downconvert_worker)(struct ocfs2_lock_res *, int);
+
+	/*
+	 * LOCK_TYPE_* flags which describe the specific requirements
+	 * of a lock type. Descriptions of each individual flag follow.
+	 */
+	int flags;
+};
+
+/*
+ * Some locks want to "refresh" potentially stale data when a
+ * meaningful (PRMODE or EXMODE) lock level is first obtained. If this
+ * flag is set, the OCFS2_LOCK_NEEDS_REFRESH flag will be set on the
+ * individual lockres l_flags member from the ast function. It is
+ * expected that the locking wrapper will clear the
+ * OCFS2_LOCK_NEEDS_REFRESH flag when done.
+ */
+#define LOCK_TYPE_REQUIRES_REFRESH 0x1
+
+/*
+ * Indicate that a lock type makes use of the lock value block. The
+ * ->set_lvb lock type callback must be defined.
+ */
+#define LOCK_TYPE_USES_LVB		0x2
+
+static struct ocfs2_lock_res_ops ocfs2_inode_rw_lops = {
+	.get_osb	= ocfs2_get_inode_osb,
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_inode_inode_lops = {
+	.get_osb	= ocfs2_get_inode_osb,
+	.check_downconvert = ocfs2_check_meta_downconvert,
+	.set_lvb	= ocfs2_set_meta_lvb,
+	.downconvert_worker = ocfs2_data_convert_worker,
+	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_super_lops = {
+	.flags		= LOCK_TYPE_REQUIRES_REFRESH,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_rename_lops = {
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_nfs_sync_lops = {
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_trim_fs_lops = {
+	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_orphan_scan_lops = {
+	.flags		= LOCK_TYPE_REQUIRES_REFRESH|LOCK_TYPE_USES_LVB,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_dentry_lops = {
+	.get_osb	= ocfs2_get_dentry_osb,
+	.post_unlock	= ocfs2_dentry_post_unlock,
+	.downconvert_worker = ocfs2_dentry_convert_worker,
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_inode_open_lops = {
+	.get_osb	= ocfs2_get_inode_osb,
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
+	.get_osb	= ocfs2_get_file_osb,
+	.flags		= 0,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_qinfo_lops = {
+	.set_lvb	= ocfs2_set_qinfo_lvb,
+	.get_osb	= ocfs2_get_qinfo_osb,
+	.flags		= LOCK_TYPE_REQUIRES_REFRESH | LOCK_TYPE_USES_LVB,
+};
+
+static struct ocfs2_lock_res_ops ocfs2_refcount_block_lops = {
+	.check_downconvert = ocfs2_check_refcount_downconvert,
+	.downconvert_worker = ocfs2_refcount_convert_worker,
+	.flags		= 0,
+};
+
+static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
+{
+	return lockres->l_type == OCFS2_LOCK_TYPE_META ||
+		lockres->l_type == OCFS2_LOCK_TYPE_RW ||
+		lockres->l_type == OCFS2_LOCK_TYPE_OPEN;
+}
+
+static inline struct ocfs2_lock_res *ocfs2_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
+{
+	return container_of(lksb, struct ocfs2_lock_res, l_lksb);
+}
+
+static inline struct inode *ocfs2_lock_res_inode(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON(!ocfs2_is_inode_lock(lockres));
+
+	return (struct inode *) lockres->l_priv;
+}
+
+static inline struct ocfs2_dentry_lock *ocfs2_lock_res_dl(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_DENTRY);
+
+	return (struct ocfs2_dentry_lock *)lockres->l_priv;
+}
+
+static inline struct ocfs2_mem_dqinfo *ocfs2_lock_res_qinfo(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON(lockres->l_type != OCFS2_LOCK_TYPE_QINFO);
+
+	return (struct ocfs2_mem_dqinfo *)lockres->l_priv;
+}
+
+static inline struct ocfs2_refcount_tree *
+ocfs2_lock_res_refcount_tree(struct ocfs2_lock_res *res)
+{
+	return container_of(res, struct ocfs2_refcount_tree, rf_lockres);
+}
+
+static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *lockres)
+{
+	if (lockres->l_ops->get_osb)
+		return lockres->l_ops->get_osb(lockres);
+
+	return (struct ocfs2_super *)lockres->l_priv;
+}
+
+static int ocfs2_lock_create(struct ocfs2_super *osb,
+			     struct ocfs2_lock_res *lockres,
+			     int level,
+			     u32 dlm_flags);
+static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
+						     int wanted);
+static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
+				   struct ocfs2_lock_res *lockres,
+				   int level, unsigned long caller_ip);
+static inline void ocfs2_cluster_unlock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres,
+					int level)
+{
+	__ocfs2_cluster_unlock(osb, lockres, level, _RET_IP_);
+}
+
+static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres);
+static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres);
+static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres);
+static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres, int level);
+static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres);
+static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
+						int convert);
+#define ocfs2_log_dlm_error(_func, _err, _lockres) do {					\
+	if ((_lockres)->l_type != OCFS2_LOCK_TYPE_DENTRY)				\
+		mlog(ML_ERROR, "DLM error %d while calling %s on resource %s\n",	\
+		     _err, _func, _lockres->l_name);					\
+	else										\
+		mlog(ML_ERROR, "DLM error %d while calling %s on resource %.*s%08x\n",	\
+		     _err, _func, OCFS2_DENTRY_LOCK_INO_START - 1, (_lockres)->l_name,	\
+		     (unsigned int)ocfs2_get_dentry_lock_ino(_lockres));		\
+} while (0)
+static int ocfs2_downconvert_thread(void *arg);
+static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres);
+static int ocfs2_inode_lock_update(struct inode *inode,
+				  struct buffer_head **bh);
+static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
+static inline int ocfs2_highest_compat_lock_level(int level);
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+					      int new_level);
+static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
+				  struct ocfs2_lock_res *lockres,
+				  int new_level,
+				  int lvb,
+				  unsigned int generation);
+static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
+				        struct ocfs2_lock_res *lockres);
+static int ocfs2_cancel_convert(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres);
+
+
+static void ocfs2_build_lock_name(enum ocfs2_lock_type type,
+				  u64 blkno,
+				  u32 generation,
+				  char *name)
+{
+	int len;
+
+	BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);
+
+	len = snprintf(name, OCFS2_LOCK_ID_MAX_LEN, "%c%s%016llx%08x",
+		       ocfs2_lock_type_char(type), OCFS2_LOCK_ID_PAD,
+		       (long long)blkno, generation);
+
+	BUG_ON(len != (OCFS2_LOCK_ID_MAX_LEN - 1));
+
+	mlog(0, "built lock resource with name: %s\n", name);
+}
+
+static DEFINE_SPINLOCK(ocfs2_dlm_tracking_lock);
+
+static void ocfs2_add_lockres_tracking(struct ocfs2_lock_res *res,
+				       struct ocfs2_dlm_debug *dlm_debug)
+{
+	mlog(0, "Add tracking for lockres %s\n", res->l_name);
+
+	spin_lock(&ocfs2_dlm_tracking_lock);
+	list_add(&res->l_debug_list, &dlm_debug->d_lockres_tracking);
+	spin_unlock(&ocfs2_dlm_tracking_lock);
+}
+
+static void ocfs2_remove_lockres_tracking(struct ocfs2_lock_res *res)
+{
+	spin_lock(&ocfs2_dlm_tracking_lock);
+	if (!list_empty(&res->l_debug_list))
+		list_del_init(&res->l_debug_list);
+	spin_unlock(&ocfs2_dlm_tracking_lock);
+}
+
+#ifdef CONFIG_OCFS2_FS_STATS
+static void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
+{
+	res->l_lock_refresh = 0;
+	res->l_lock_wait = 0;
+	memset(&res->l_lock_prmode, 0, sizeof(struct ocfs2_lock_stats));
+	memset(&res->l_lock_exmode, 0, sizeof(struct ocfs2_lock_stats));
+}
+
+static void ocfs2_update_lock_stats(struct ocfs2_lock_res *res, int level,
+				    struct ocfs2_mask_waiter *mw, int ret)
+{
+	u32 usec;
+	ktime_t kt;
+	struct ocfs2_lock_stats *stats;
+
+	if (level == LKM_PRMODE)
+		stats = &res->l_lock_prmode;
+	else if (level == LKM_EXMODE)
+		stats = &res->l_lock_exmode;
+	else
+		return;
+
+	kt = ktime_sub(ktime_get(), mw->mw_lock_start);
+	usec = ktime_to_us(kt);
+
+	stats->ls_gets++;
+	stats->ls_total += ktime_to_ns(kt);
+	/* overflow */
+	if (unlikely(stats->ls_gets == 0)) {
+		stats->ls_gets++;
+		stats->ls_total = ktime_to_ns(kt);
+	}
+
+	if (stats->ls_max < usec)
+		stats->ls_max = usec;
+
+	if (ret)
+		stats->ls_fail++;
+
+	stats->ls_last = ktime_to_us(ktime_get_real());
+}
+
+static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
+{
+	lockres->l_lock_refresh++;
+}
+
+static inline void ocfs2_track_lock_wait(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_mask_waiter *mw;
+
+	if (list_empty(&lockres->l_mask_waiters)) {
+		lockres->l_lock_wait = 0;
+		return;
+	}
+
+	mw = list_first_entry(&lockres->l_mask_waiters,
+				struct ocfs2_mask_waiter, mw_item);
+	lockres->l_lock_wait =
+			ktime_to_us(ktime_mono_to_real(mw->mw_lock_start));
+}
+
+static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
+{
+	mw->mw_lock_start = ktime_get();
+}
+#else
+static inline void ocfs2_init_lock_stats(struct ocfs2_lock_res *res)
+{
+}
+static inline void ocfs2_update_lock_stats(struct ocfs2_lock_res *res,
+			   int level, struct ocfs2_mask_waiter *mw, int ret)
+{
+}
+static inline void ocfs2_track_lock_refresh(struct ocfs2_lock_res *lockres)
+{
+}
+static inline void ocfs2_track_lock_wait(struct ocfs2_lock_res *lockres)
+{
+}
+static inline void ocfs2_init_start_time(struct ocfs2_mask_waiter *mw)
+{
+}
+#endif
+
+static void ocfs2_lock_res_init_common(struct ocfs2_super *osb,
+				       struct ocfs2_lock_res *res,
+				       enum ocfs2_lock_type type,
+				       struct ocfs2_lock_res_ops *ops,
+				       void *priv)
+{
+	res->l_type          = type;
+	res->l_ops           = ops;
+	res->l_priv          = priv;
+
+	res->l_level         = DLM_LOCK_IV;
+	res->l_requested     = DLM_LOCK_IV;
+	res->l_blocking      = DLM_LOCK_IV;
+	res->l_action        = OCFS2_AST_INVALID;
+	res->l_unlock_action = OCFS2_UNLOCK_INVALID;
+
+	res->l_flags         = OCFS2_LOCK_INITIALIZED;
+
+	ocfs2_add_lockres_tracking(res, osb->osb_dlm_debug);
+
+	ocfs2_init_lock_stats(res);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (type != OCFS2_LOCK_TYPE_OPEN)
+		lockdep_init_map(&res->l_lockdep_map, ocfs2_lock_type_strings[type],
+				 &lockdep_keys[type], 0);
+	else
+		res->l_lockdep_map.key = NULL;
+#endif
+}
+
+void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res)
+{
+	/* This also clears out the lock status block */
+	memset(res, 0, sizeof(struct ocfs2_lock_res));
+	spin_lock_init(&res->l_lock);
+	init_waitqueue_head(&res->l_event);
+	INIT_LIST_HEAD(&res->l_blocked_list);
+	INIT_LIST_HEAD(&res->l_mask_waiters);
+	INIT_LIST_HEAD(&res->l_holders);
+}
+
+void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
+			       enum ocfs2_lock_type type,
+			       unsigned int generation,
+			       struct inode *inode)
+{
+	struct ocfs2_lock_res_ops *ops;
+
+	switch(type) {
+		case OCFS2_LOCK_TYPE_RW:
+			ops = &ocfs2_inode_rw_lops;
+			break;
+		case OCFS2_LOCK_TYPE_META:
+			ops = &ocfs2_inode_inode_lops;
+			break;
+		case OCFS2_LOCK_TYPE_OPEN:
+			ops = &ocfs2_inode_open_lops;
+			break;
+		default:
+			mlog_bug_on_msg(1, "type: %d\n", type);
+			ops = NULL; /* thanks, gcc */
+			break;
+	}
+
+	ocfs2_build_lock_name(type, OCFS2_I(inode)->ip_blkno,
+			      generation, res->l_name);
+	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), res, type, ops, inode);
+}
+
+static struct ocfs2_super *ocfs2_get_inode_osb(struct ocfs2_lock_res *lockres)
+{
+	struct inode *inode = ocfs2_lock_res_inode(lockres);
+
+	return OCFS2_SB(inode->i_sb);
+}
+
+static struct ocfs2_super *ocfs2_get_qinfo_osb(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_mem_dqinfo *info = lockres->l_priv;
+
+	return OCFS2_SB(info->dqi_gi.dqi_sb);
+}
+
+static struct ocfs2_super *ocfs2_get_file_osb(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_file_private *fp = lockres->l_priv;
+
+	return OCFS2_SB(fp->fp_file->f_mapping->host->i_sb);
+}
+
+static __u64 ocfs2_get_dentry_lock_ino(struct ocfs2_lock_res *lockres)
+{
+	__be64 inode_blkno_be;
+
+	memcpy(&inode_blkno_be, &lockres->l_name[OCFS2_DENTRY_LOCK_INO_START],
+	       sizeof(__be64));
+
+	return be64_to_cpu(inode_blkno_be);
+}
+
+static struct ocfs2_super *ocfs2_get_dentry_osb(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_dentry_lock *dl = lockres->l_priv;
+
+	return OCFS2_SB(dl->dl_inode->i_sb);
+}
+
+void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
+				u64 parent, struct inode *inode)
+{
+	int len;
+	u64 inode_blkno = OCFS2_I(inode)->ip_blkno;
+	__be64 inode_blkno_be = cpu_to_be64(inode_blkno);
+	struct ocfs2_lock_res *lockres = &dl->dl_lockres;
+
+	ocfs2_lock_res_init_once(lockres);
+
+	/*
+	 * Unfortunately, the standard lock naming scheme won't work
+	 * here because we have two 16 byte values to use. Instead,
+	 * we'll stuff the inode number as a binary value. We still
+	 * want error prints to show something without garbling the
+	 * display, so drop a null byte in there before the inode
+	 * number. A future version of OCFS2 will likely use all
+	 * binary lock names. The stringified names have been a
+	 * tremendous aid in debugging, but now that the debugfs
+	 * interface exists, we can mangle things there if need be.
+	 *
+	 * NOTE: We also drop the standard "pad" value (the total lock
+	 * name size stays the same though - the last part is all
+	 * zeros due to the memset in ocfs2_lock_res_init_once()
+	 */
+	len = snprintf(lockres->l_name, OCFS2_DENTRY_LOCK_INO_START,
+		       "%c%016llx",
+		       ocfs2_lock_type_char(OCFS2_LOCK_TYPE_DENTRY),
+		       (long long)parent);
+
+	BUG_ON(len != (OCFS2_DENTRY_LOCK_INO_START - 1));
+
+	memcpy(&lockres->l_name[OCFS2_DENTRY_LOCK_INO_START], &inode_blkno_be,
+	       sizeof(__be64));
+
+	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
+				   OCFS2_LOCK_TYPE_DENTRY, &ocfs2_dentry_lops,
+				   dl);
+}
+
+static void ocfs2_super_lock_res_init(struct ocfs2_lock_res *res,
+				      struct ocfs2_super *osb)
+{
+	/* Superblock lockres doesn't come from a slab so we call init
+	 * once on it manually.  */
+	ocfs2_lock_res_init_once(res);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_SUPER, OCFS2_SUPER_BLOCK_BLKNO,
+			      0, res->l_name);
+	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_SUPER,
+				   &ocfs2_super_lops, osb);
+}
+
+static void ocfs2_rename_lock_res_init(struct ocfs2_lock_res *res,
+				       struct ocfs2_super *osb)
+{
+	/* Rename lockres doesn't come from a slab so we call init
+	 * once on it manually.  */
+	ocfs2_lock_res_init_once(res);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_RENAME, 0, 0, res->l_name);
+	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_RENAME,
+				   &ocfs2_rename_lops, osb);
+}
+
+static void ocfs2_nfs_sync_lock_res_init(struct ocfs2_lock_res *res,
+					 struct ocfs2_super *osb)
+{
+	/* nfs_sync lockres doesn't come from a slab so we call init
+	 * once on it manually.  */
+	ocfs2_lock_res_init_once(res);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_NFS_SYNC, 0, 0, res->l_name);
+	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_NFS_SYNC,
+				   &ocfs2_nfs_sync_lops, osb);
+}
+
+static void ocfs2_nfs_sync_lock_init(struct ocfs2_super *osb)
+{
+	ocfs2_nfs_sync_lock_res_init(&osb->osb_nfs_sync_lockres, osb);
+	init_rwsem(&osb->nfs_sync_rwlock);
+}
+
+void ocfs2_trim_fs_lock_res_init(struct ocfs2_super *osb)
+{
+	struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
+
+	/* Only one trimfs thread are allowed to work at the same time. */
+	mutex_lock(&osb->obs_trim_fs_mutex);
+
+	ocfs2_lock_res_init_once(lockres);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_TRIM_FS, 0, 0, lockres->l_name);
+	ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_TRIM_FS,
+				   &ocfs2_trim_fs_lops, osb);
+}
+
+void ocfs2_trim_fs_lock_res_uninit(struct ocfs2_super *osb)
+{
+	struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
+
+	ocfs2_simple_drop_lockres(osb, lockres);
+	ocfs2_lock_res_free(lockres);
+
+	mutex_unlock(&osb->obs_trim_fs_mutex);
+}
+
+static void ocfs2_orphan_scan_lock_res_init(struct ocfs2_lock_res *res,
+					    struct ocfs2_super *osb)
+{
+	ocfs2_lock_res_init_once(res);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_ORPHAN_SCAN, 0, 0, res->l_name);
+	ocfs2_lock_res_init_common(osb, res, OCFS2_LOCK_TYPE_ORPHAN_SCAN,
+				   &ocfs2_orphan_scan_lops, osb);
+}
+
+void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
+			      struct ocfs2_file_private *fp)
+{
+	struct inode *inode = fp->fp_file->f_mapping->host;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+
+	ocfs2_lock_res_init_once(lockres);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_FLOCK, oi->ip_blkno,
+			      inode->i_generation, lockres->l_name);
+	ocfs2_lock_res_init_common(OCFS2_SB(inode->i_sb), lockres,
+				   OCFS2_LOCK_TYPE_FLOCK, &ocfs2_flock_lops,
+				   fp);
+	lockres->l_flags |= OCFS2_LOCK_NOCACHE;
+}
+
+void ocfs2_qinfo_lock_res_init(struct ocfs2_lock_res *lockres,
+			       struct ocfs2_mem_dqinfo *info)
+{
+	ocfs2_lock_res_init_once(lockres);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_QINFO, info->dqi_gi.dqi_type,
+			      0, lockres->l_name);
+	ocfs2_lock_res_init_common(OCFS2_SB(info->dqi_gi.dqi_sb), lockres,
+				   OCFS2_LOCK_TYPE_QINFO, &ocfs2_qinfo_lops,
+				   info);
+}
+
+void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
+				  struct ocfs2_super *osb, u64 ref_blkno,
+				  unsigned int generation)
+{
+	ocfs2_lock_res_init_once(lockres);
+	ocfs2_build_lock_name(OCFS2_LOCK_TYPE_REFCOUNT, ref_blkno,
+			      generation, lockres->l_name);
+	ocfs2_lock_res_init_common(osb, lockres, OCFS2_LOCK_TYPE_REFCOUNT,
+				   &ocfs2_refcount_block_lops, osb);
+}
+
+void ocfs2_lock_res_free(struct ocfs2_lock_res *res)
+{
+	if (!(res->l_flags & OCFS2_LOCK_INITIALIZED))
+		return;
+
+	ocfs2_remove_lockres_tracking(res);
+
+	mlog_bug_on_msg(!list_empty(&res->l_blocked_list),
+			"Lockres %s is on the blocked list\n",
+			res->l_name);
+	mlog_bug_on_msg(!list_empty(&res->l_mask_waiters),
+			"Lockres %s has mask waiters pending\n",
+			res->l_name);
+	mlog_bug_on_msg(spin_is_locked(&res->l_lock),
+			"Lockres %s is locked\n",
+			res->l_name);
+	mlog_bug_on_msg(res->l_ro_holders,
+			"Lockres %s has %u ro holders\n",
+			res->l_name, res->l_ro_holders);
+	mlog_bug_on_msg(res->l_ex_holders,
+			"Lockres %s has %u ex holders\n",
+			res->l_name, res->l_ex_holders);
+
+	/* Need to clear out the lock status block for the dlm */
+	memset(&res->l_lksb, 0, sizeof(res->l_lksb));
+
+	res->l_flags = 0UL;
+}
+
+/*
+ * Keep a list of processes who have interest in a lockres.
+ * Note: this is now only uesed for check recursive cluster locking.
+ */
+static inline void ocfs2_add_holder(struct ocfs2_lock_res *lockres,
+				   struct ocfs2_lock_holder *oh)
+{
+	INIT_LIST_HEAD(&oh->oh_list);
+	oh->oh_owner_pid = get_pid(task_pid(current));
+
+	spin_lock(&lockres->l_lock);
+	list_add_tail(&oh->oh_list, &lockres->l_holders);
+	spin_unlock(&lockres->l_lock);
+}
+
+static struct ocfs2_lock_holder *
+ocfs2_pid_holder(struct ocfs2_lock_res *lockres,
+		struct pid *pid)
+{
+	struct ocfs2_lock_holder *oh;
+
+	spin_lock(&lockres->l_lock);
+	list_for_each_entry(oh, &lockres->l_holders, oh_list) {
+		if (oh->oh_owner_pid == pid) {
+			spin_unlock(&lockres->l_lock);
+			return oh;
+		}
+	}
+	spin_unlock(&lockres->l_lock);
+	return NULL;
+}
+
+static inline void ocfs2_remove_holder(struct ocfs2_lock_res *lockres,
+				       struct ocfs2_lock_holder *oh)
+{
+	spin_lock(&lockres->l_lock);
+	list_del(&oh->oh_list);
+	spin_unlock(&lockres->l_lock);
+
+	put_pid(oh->oh_owner_pid);
+}
+
+
+static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
+				     int level)
+{
+	BUG_ON(!lockres);
+
+	switch(level) {
+	case DLM_LOCK_EX:
+		lockres->l_ex_holders++;
+		break;
+	case DLM_LOCK_PR:
+		lockres->l_ro_holders++;
+		break;
+	default:
+		BUG();
+	}
+}
+
+static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
+				     int level)
+{
+	BUG_ON(!lockres);
+
+	switch(level) {
+	case DLM_LOCK_EX:
+		BUG_ON(!lockres->l_ex_holders);
+		lockres->l_ex_holders--;
+		break;
+	case DLM_LOCK_PR:
+		BUG_ON(!lockres->l_ro_holders);
+		lockres->l_ro_holders--;
+		break;
+	default:
+		BUG();
+	}
+}
+
+/* WARNING: This function lives in a world where the only three lock
+ * levels are EX, PR, and NL. It *will* have to be adjusted when more
+ * lock types are added. */
+static inline int ocfs2_highest_compat_lock_level(int level)
+{
+	int new_level = DLM_LOCK_EX;
+
+	if (level == DLM_LOCK_EX)
+		new_level = DLM_LOCK_NL;
+	else if (level == DLM_LOCK_PR)
+		new_level = DLM_LOCK_PR;
+	return new_level;
+}
+
+static void lockres_set_flags(struct ocfs2_lock_res *lockres,
+			      unsigned long newflags)
+{
+	struct ocfs2_mask_waiter *mw, *tmp;
+
+ 	assert_spin_locked(&lockres->l_lock);
+
+	lockres->l_flags = newflags;
+
+	list_for_each_entry_safe(mw, tmp, &lockres->l_mask_waiters, mw_item) {
+		if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
+			continue;
+
+		list_del_init(&mw->mw_item);
+		mw->mw_status = 0;
+		complete(&mw->mw_complete);
+		ocfs2_track_lock_wait(lockres);
+	}
+}
+static void lockres_or_flags(struct ocfs2_lock_res *lockres, unsigned long or)
+{
+	lockres_set_flags(lockres, lockres->l_flags | or);
+}
+static void lockres_clear_flags(struct ocfs2_lock_res *lockres,
+				unsigned long clear)
+{
+	lockres_set_flags(lockres, lockres->l_flags & ~clear);
+}
+
+static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
+	BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
+
+	lockres->l_level = lockres->l_requested;
+	if (lockres->l_level <=
+	    ocfs2_highest_compat_lock_level(lockres->l_blocking)) {
+		lockres->l_blocking = DLM_LOCK_NL;
+		lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
+	}
+	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+}
+
+static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
+
+	/* Convert from RO to EX doesn't really need anything as our
+	 * information is already up to data. Convert from NL to
+	 * *anything* however should mark ourselves as needing an
+	 * update */
+	if (lockres->l_level == DLM_LOCK_NL &&
+	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
+		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
+
+	lockres->l_level = lockres->l_requested;
+
+	/*
+	 * We set the OCFS2_LOCK_UPCONVERT_FINISHING flag before clearing
+	 * the OCFS2_LOCK_BUSY flag to prevent the dc thread from
+	 * downconverting the lock before the upconvert has fully completed.
+	 * Do not prevent the dc thread from downconverting if NONBLOCK lock
+	 * had already returned.
+	 */
+	if (!(lockres->l_flags & OCFS2_LOCK_NONBLOCK_FINISHED))
+		lockres_or_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
+	else
+		lockres_clear_flags(lockres, OCFS2_LOCK_NONBLOCK_FINISHED);
+
+	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+}
+
+static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *lockres)
+{
+	BUG_ON((!(lockres->l_flags & OCFS2_LOCK_BUSY)));
+	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
+
+	if (lockres->l_requested > DLM_LOCK_NL &&
+	    !(lockres->l_flags & OCFS2_LOCK_LOCAL) &&
+	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
+		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
+
+	lockres->l_level = lockres->l_requested;
+	lockres_or_flags(lockres, OCFS2_LOCK_ATTACHED);
+	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+}
+
+static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
+				     int level)
+{
+	int needs_downconvert = 0;
+
+	assert_spin_locked(&lockres->l_lock);
+
+	if (level > lockres->l_blocking) {
+		/* only schedule a downconvert if we haven't already scheduled
+		 * one that goes low enough to satisfy the level we're
+		 * blocking.  this also catches the case where we get
+		 * duplicate BASTs */
+		if (ocfs2_highest_compat_lock_level(level) <
+		    ocfs2_highest_compat_lock_level(lockres->l_blocking))
+			needs_downconvert = 1;
+
+		lockres->l_blocking = level;
+	}
+
+	mlog(ML_BASTS, "lockres %s, block %d, level %d, l_block %d, dwn %d\n",
+	     lockres->l_name, level, lockres->l_level, lockres->l_blocking,
+	     needs_downconvert);
+
+	if (needs_downconvert)
+		lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
+	mlog(0, "needs_downconvert = %d\n", needs_downconvert);
+	return needs_downconvert;
+}
+
+/*
+ * OCFS2_LOCK_PENDING and l_pending_gen.
+ *
+ * Why does OCFS2_LOCK_PENDING exist?  To close a race between setting
+ * OCFS2_LOCK_BUSY and calling ocfs2_dlm_lock().  See ocfs2_unblock_lock()
+ * for more details on the race.
+ *
+ * OCFS2_LOCK_PENDING closes the race quite nicely.  However, it introduces
+ * a race on itself.  In o2dlm, we can get the ast before ocfs2_dlm_lock()
+ * returns.  The ast clears OCFS2_LOCK_BUSY, and must therefore clear
+ * OCFS2_LOCK_PENDING at the same time.  When ocfs2_dlm_lock() returns,
+ * the caller is going to try to clear PENDING again.  If nothing else is
+ * happening, __lockres_clear_pending() sees PENDING is unset and does
+ * nothing.
+ *
+ * But what if another path (eg downconvert thread) has just started a
+ * new locking action?  The other path has re-set PENDING.  Our path
+ * cannot clear PENDING, because that will re-open the original race
+ * window.
+ *
+ * [Example]
+ *
+ * ocfs2_meta_lock()
+ *  ocfs2_cluster_lock()
+ *   set BUSY
+ *   set PENDING
+ *   drop l_lock
+ *   ocfs2_dlm_lock()
+ *    ocfs2_locking_ast()		ocfs2_downconvert_thread()
+ *     clear PENDING			 ocfs2_unblock_lock()
+ *					  take_l_lock
+ *					  !BUSY
+ *					  ocfs2_prepare_downconvert()
+ *					   set BUSY
+ *					   set PENDING
+ *					  drop l_lock
+ *   take l_lock
+ *   clear PENDING
+ *   drop l_lock
+ *			<window>
+ *					  ocfs2_dlm_lock()
+ *
+ * So as you can see, we now have a window where l_lock is not held,
+ * PENDING is not set, and ocfs2_dlm_lock() has not been called.
+ *
+ * The core problem is that ocfs2_cluster_lock() has cleared the PENDING
+ * set by ocfs2_prepare_downconvert().  That wasn't nice.
+ *
+ * To solve this we introduce l_pending_gen.  A call to
+ * lockres_clear_pending() will only do so when it is passed a generation
+ * number that matches the lockres.  lockres_set_pending() will return the
+ * current generation number.  When ocfs2_cluster_lock() goes to clear
+ * PENDING, it passes the generation it got from set_pending().  In our
+ * example above, the generation numbers will *not* match.  Thus,
+ * ocfs2_cluster_lock() will not clear the PENDING set by
+ * ocfs2_prepare_downconvert().
+ */
+
+/* Unlocked version for ocfs2_locking_ast() */
+static void __lockres_clear_pending(struct ocfs2_lock_res *lockres,
+				    unsigned int generation,
+				    struct ocfs2_super *osb)
+{
+	assert_spin_locked(&lockres->l_lock);
+
+	/*
+	 * The ast and locking functions can race us here.  The winner
+	 * will clear pending, the loser will not.
+	 */
+	if (!(lockres->l_flags & OCFS2_LOCK_PENDING) ||
+	    (lockres->l_pending_gen != generation))
+		return;
+
+	lockres_clear_flags(lockres, OCFS2_LOCK_PENDING);
+	lockres->l_pending_gen++;
+
+	/*
+	 * The downconvert thread may have skipped us because we
+	 * were PENDING.  Wake it up.
+	 */
+	if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
+		ocfs2_wake_downconvert_thread(osb);
+}
+
+/* Locked version for callers of ocfs2_dlm_lock() */
+static void lockres_clear_pending(struct ocfs2_lock_res *lockres,
+				  unsigned int generation,
+				  struct ocfs2_super *osb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	__lockres_clear_pending(lockres, generation, osb);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+static unsigned int lockres_set_pending(struct ocfs2_lock_res *lockres)
+{
+	assert_spin_locked(&lockres->l_lock);
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
+
+	lockres_or_flags(lockres, OCFS2_LOCK_PENDING);
+
+	return lockres->l_pending_gen;
+}
+
+static void ocfs2_blocking_ast(struct ocfs2_dlm_lksb *lksb, int level)
+{
+	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
+	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
+	int needs_downconvert;
+	unsigned long flags;
+
+	BUG_ON(level <= DLM_LOCK_NL);
+
+	mlog(ML_BASTS, "BAST fired for lockres %s, blocking %d, level %d, "
+	     "type %s\n", lockres->l_name, level, lockres->l_level,
+	     ocfs2_lock_type_string(lockres->l_type));
+
+	/*
+	 * We can skip the bast for locks which don't enable caching -
+	 * they'll be dropped at the earliest possible time anyway.
+	 */
+	if (lockres->l_flags & OCFS2_LOCK_NOCACHE)
+		return;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	needs_downconvert = ocfs2_generic_handle_bast(lockres, level);
+	if (needs_downconvert)
+		ocfs2_schedule_blocked_lock(osb, lockres);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	wake_up(&lockres->l_event);
+
+	ocfs2_wake_downconvert_thread(osb);
+}
+
+static void ocfs2_locking_ast(struct ocfs2_dlm_lksb *lksb)
+{
+	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
+	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
+	unsigned long flags;
+	int status;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+
+	status = ocfs2_dlm_lock_status(&lockres->l_lksb);
+
+	if (status == -EAGAIN) {
+		lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+		goto out;
+	}
+
+	if (status) {
+		mlog(ML_ERROR, "lockres %s: lksb status value of %d!\n",
+		     lockres->l_name, status);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		return;
+	}
+
+	mlog(ML_BASTS, "AST fired for lockres %s, action %d, unlock %d, "
+	     "level %d => %d\n", lockres->l_name, lockres->l_action,
+	     lockres->l_unlock_action, lockres->l_level, lockres->l_requested);
+
+	switch(lockres->l_action) {
+	case OCFS2_AST_ATTACH:
+		ocfs2_generic_handle_attach_action(lockres);
+		lockres_clear_flags(lockres, OCFS2_LOCK_LOCAL);
+		break;
+	case OCFS2_AST_CONVERT:
+		ocfs2_generic_handle_convert_action(lockres);
+		break;
+	case OCFS2_AST_DOWNCONVERT:
+		ocfs2_generic_handle_downconvert_action(lockres);
+		break;
+	default:
+		mlog(ML_ERROR, "lockres %s: AST fired with invalid action: %u, "
+		     "flags 0x%lx, unlock: %u\n",
+		     lockres->l_name, lockres->l_action, lockres->l_flags,
+		     lockres->l_unlock_action);
+		BUG();
+	}
+out:
+	/* set it to something invalid so if we get called again we
+	 * can catch it. */
+	lockres->l_action = OCFS2_AST_INVALID;
+
+	/* Did we try to cancel this lock?  Clear that state */
+	if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT)
+		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
+
+	/*
+	 * We may have beaten the locking functions here.  We certainly
+	 * know that dlm_lock() has been called :-)
+	 * Because we can't have two lock calls in flight at once, we
+	 * can use lockres->l_pending_gen.
+	 */
+	__lockres_clear_pending(lockres, lockres->l_pending_gen,  osb);
+
+	wake_up(&lockres->l_event);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+static void ocfs2_unlock_ast(struct ocfs2_dlm_lksb *lksb, int error)
+{
+	struct ocfs2_lock_res *lockres = ocfs2_lksb_to_lock_res(lksb);
+	unsigned long flags;
+
+	mlog(ML_BASTS, "UNLOCK AST fired for lockres %s, action = %d\n",
+	     lockres->l_name, lockres->l_unlock_action);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (error) {
+		mlog(ML_ERROR, "Dlm passes error %d for lock %s, "
+		     "unlock_action %d\n", error, lockres->l_name,
+		     lockres->l_unlock_action);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		return;
+	}
+
+	switch(lockres->l_unlock_action) {
+	case OCFS2_UNLOCK_CANCEL_CONVERT:
+		mlog(0, "Cancel convert success for %s\n", lockres->l_name);
+		lockres->l_action = OCFS2_AST_INVALID;
+		/* Downconvert thread may have requeued this lock, we
+		 * need to wake it. */
+		if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
+			ocfs2_wake_downconvert_thread(ocfs2_get_lockres_osb(lockres));
+		break;
+	case OCFS2_UNLOCK_DROP_LOCK:
+		lockres->l_level = DLM_LOCK_IV;
+		break;
+	default:
+		BUG();
+	}
+
+	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+	lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
+	wake_up(&lockres->l_event);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+/*
+ * This is the filesystem locking protocol.  It provides the lock handling
+ * hooks for the underlying DLM.  It has a maximum version number.
+ * The version number allows interoperability with systems running at
+ * the same major number and an equal or smaller minor number.
+ *
+ * Whenever the filesystem does new things with locks (adds or removes a
+ * lock, orders them differently, does different things underneath a lock),
+ * the version must be changed.  The protocol is negotiated when joining
+ * the dlm domain.  A node may join the domain if its major version is
+ * identical to all other nodes and its minor version is greater than
+ * or equal to all other nodes.  When its minor version is greater than
+ * the other nodes, it will run at the minor version specified by the
+ * other nodes.
+ *
+ * If a locking change is made that will not be compatible with older
+ * versions, the major number must be increased and the minor version set
+ * to zero.  If a change merely adds a behavior that can be disabled when
+ * speaking to older versions, the minor version must be increased.  If a
+ * change adds a fully backwards compatible change (eg, LVB changes that
+ * are just ignored by older versions), the version does not need to be
+ * updated.
+ */
+static struct ocfs2_locking_protocol lproto = {
+	.lp_max_version = {
+		.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+		.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+	},
+	.lp_lock_ast		= ocfs2_locking_ast,
+	.lp_blocking_ast	= ocfs2_blocking_ast,
+	.lp_unlock_ast		= ocfs2_unlock_ast,
+};
+
+void ocfs2_set_locking_protocol(void)
+{
+	ocfs2_stack_glue_set_max_proto_version(&lproto.lp_max_version);
+}
+
+static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
+						int convert)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+	lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
+	if (convert)
+		lockres->l_action = OCFS2_AST_INVALID;
+	else
+		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	wake_up(&lockres->l_event);
+}
+
+/* Note: If we detect another process working on the lock (i.e.,
+ * OCFS2_LOCK_BUSY), we'll bail out returning 0. It's up to the caller
+ * to do the right thing in that case.
+ */
+static int ocfs2_lock_create(struct ocfs2_super *osb,
+			     struct ocfs2_lock_res *lockres,
+			     int level,
+			     u32 dlm_flags)
+{
+	int ret = 0;
+	unsigned long flags;
+	unsigned int gen;
+
+	mlog(0, "lock %s, level = %d, flags = %u\n", lockres->l_name, level,
+	     dlm_flags);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if ((lockres->l_flags & OCFS2_LOCK_ATTACHED) ||
+	    (lockres->l_flags & OCFS2_LOCK_BUSY)) {
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		goto bail;
+	}
+
+	lockres->l_action = OCFS2_AST_ATTACH;
+	lockres->l_requested = level;
+	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+	gen = lockres_set_pending(lockres);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ret = ocfs2_dlm_lock(osb->cconn,
+			     level,
+			     &lockres->l_lksb,
+			     dlm_flags,
+			     lockres->l_name,
+			     OCFS2_LOCK_ID_MAX_LEN - 1);
+	lockres_clear_pending(lockres, gen, osb);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
+		ocfs2_recover_from_dlm_error(lockres, 1);
+	}
+
+	mlog(0, "lock %s, return from ocfs2_dlm_lock\n", lockres->l_name);
+
+bail:
+	return ret;
+}
+
+static inline int ocfs2_check_wait_flag(struct ocfs2_lock_res *lockres,
+					int flag)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	ret = lockres->l_flags & flag;
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	return ret;
+}
+
+static inline void ocfs2_wait_on_busy_lock(struct ocfs2_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_BUSY));
+}
+
+static inline void ocfs2_wait_on_refreshing_lock(struct ocfs2_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !ocfs2_check_wait_flag(lockres, OCFS2_LOCK_REFRESHING));
+}
+
+/* predict what lock level we'll be dropping down to on behalf
+ * of another node, and return true if the currently wanted
+ * level will be compatible with it. */
+static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
+						     int wanted)
+{
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
+
+	return wanted <= ocfs2_highest_compat_lock_level(lockres->l_blocking);
+}
+
+static void ocfs2_init_mask_waiter(struct ocfs2_mask_waiter *mw)
+{
+	INIT_LIST_HEAD(&mw->mw_item);
+	init_completion(&mw->mw_complete);
+	ocfs2_init_start_time(mw);
+}
+
+static int ocfs2_wait_for_mask(struct ocfs2_mask_waiter *mw)
+{
+	wait_for_completion(&mw->mw_complete);
+	/* Re-arm the completion in case we want to wait on it again */
+	reinit_completion(&mw->mw_complete);
+	return mw->mw_status;
+}
+
+static void lockres_add_mask_waiter(struct ocfs2_lock_res *lockres,
+				    struct ocfs2_mask_waiter *mw,
+				    unsigned long mask,
+				    unsigned long goal)
+{
+	BUG_ON(!list_empty(&mw->mw_item));
+
+	assert_spin_locked(&lockres->l_lock);
+
+	list_add_tail(&mw->mw_item, &lockres->l_mask_waiters);
+	mw->mw_mask = mask;
+	mw->mw_goal = goal;
+	ocfs2_track_lock_wait(lockres);
+}
+
+/* returns 0 if the mw that was removed was already satisfied, -EBUSY
+ * if the mask still hadn't reached its goal */
+static int __lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
+				      struct ocfs2_mask_waiter *mw)
+{
+	int ret = 0;
+
+	assert_spin_locked(&lockres->l_lock);
+	if (!list_empty(&mw->mw_item)) {
+		if ((lockres->l_flags & mw->mw_mask) != mw->mw_goal)
+			ret = -EBUSY;
+
+		list_del_init(&mw->mw_item);
+		init_completion(&mw->mw_complete);
+		ocfs2_track_lock_wait(lockres);
+	}
+
+	return ret;
+}
+
+static int lockres_remove_mask_waiter(struct ocfs2_lock_res *lockres,
+				      struct ocfs2_mask_waiter *mw)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	ret = __lockres_remove_mask_waiter(lockres, mw);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	return ret;
+
+}
+
+static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
+					     struct ocfs2_lock_res *lockres)
+{
+	int ret;
+
+	ret = wait_for_completion_interruptible(&mw->mw_complete);
+	if (ret)
+		lockres_remove_mask_waiter(lockres, mw);
+	else
+		ret = mw->mw_status;
+	/* Re-arm the completion in case we want to wait on it again */
+	reinit_completion(&mw->mw_complete);
+	return ret;
+}
+
+static int __ocfs2_cluster_lock(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres,
+				int level,
+				u32 lkm_flags,
+				int arg_flags,
+				int l_subclass,
+				unsigned long caller_ip)
+{
+	struct ocfs2_mask_waiter mw;
+	int wait, catch_signals = !(osb->s_mount_opt & OCFS2_MOUNT_NOINTR);
+	int ret = 0; /* gcc doesn't realize wait = 1 guarantees ret is set */
+	unsigned long flags;
+	unsigned int gen;
+	int noqueue_attempted = 0;
+	int dlm_locked = 0;
+	int kick_dc = 0;
+
+	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED)) {
+		mlog_errno(-EINVAL);
+		return -EINVAL;
+	}
+
+	ocfs2_init_mask_waiter(&mw);
+
+	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
+		lkm_flags |= DLM_LKF_VALBLK;
+
+again:
+	wait = 0;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+
+	if (catch_signals && signal_pending(current)) {
+		ret = -ERESTARTSYS;
+		goto unlock;
+	}
+
+	mlog_bug_on_msg(lockres->l_flags & OCFS2_LOCK_FREEING,
+			"Cluster lock called on freeing lockres %s! flags "
+			"0x%lx\n", lockres->l_name, lockres->l_flags);
+
+	/* We only compare against the currently granted level
+	 * here. If the lock is blocked waiting on a downconvert,
+	 * we'll get caught below. */
+	if (lockres->l_flags & OCFS2_LOCK_BUSY &&
+	    level > lockres->l_level) {
+		/* is someone sitting in dlm_lock? If so, wait on
+		 * them. */
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+		wait = 1;
+		goto unlock;
+	}
+
+	if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING) {
+		/*
+		 * We've upconverted. If the lock now has a level we can
+		 * work with, we take it. If, however, the lock is not at the
+		 * required level, we go thru the full cycle. One way this could
+		 * happen is if a process requesting an upconvert to PR is
+		 * closely followed by another requesting upconvert to an EX.
+		 * If the process requesting EX lands here, we want it to
+		 * continue attempting to upconvert and let the process
+		 * requesting PR take the lock.
+		 * If multiple processes request upconvert to PR, the first one
+		 * here will take the lock. The others will have to go thru the
+		 * OCFS2_LOCK_BLOCKED check to ensure that there is no pending
+		 * downconvert request.
+		 */
+		if (level <= lockres->l_level)
+			goto update_holders;
+	}
+
+	if (lockres->l_flags & OCFS2_LOCK_BLOCKED &&
+	    !ocfs2_may_continue_on_blocked_lock(lockres, level)) {
+		/* is the lock is currently blocked on behalf of
+		 * another node */
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BLOCKED, 0);
+		wait = 1;
+		goto unlock;
+	}
+
+	if (level > lockres->l_level) {
+		if (noqueue_attempted > 0) {
+			ret = -EAGAIN;
+			goto unlock;
+		}
+		if (lkm_flags & DLM_LKF_NOQUEUE)
+			noqueue_attempted = 1;
+
+		if (lockres->l_action != OCFS2_AST_INVALID)
+			mlog(ML_ERROR, "lockres %s has action %u pending\n",
+			     lockres->l_name, lockres->l_action);
+
+		if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
+			lockres->l_action = OCFS2_AST_ATTACH;
+			lkm_flags &= ~DLM_LKF_CONVERT;
+		} else {
+			lockres->l_action = OCFS2_AST_CONVERT;
+			lkm_flags |= DLM_LKF_CONVERT;
+		}
+
+		lockres->l_requested = level;
+		lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+		gen = lockres_set_pending(lockres);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		BUG_ON(level == DLM_LOCK_IV);
+		BUG_ON(level == DLM_LOCK_NL);
+
+		mlog(ML_BASTS, "lockres %s, convert from %d to %d\n",
+		     lockres->l_name, lockres->l_level, level);
+
+		/* call dlm_lock to upgrade lock now */
+		ret = ocfs2_dlm_lock(osb->cconn,
+				     level,
+				     &lockres->l_lksb,
+				     lkm_flags,
+				     lockres->l_name,
+				     OCFS2_LOCK_ID_MAX_LEN - 1);
+		lockres_clear_pending(lockres, gen, osb);
+		if (ret) {
+			if (!(lkm_flags & DLM_LKF_NOQUEUE) ||
+			    (ret != -EAGAIN)) {
+				ocfs2_log_dlm_error("ocfs2_dlm_lock",
+						    ret, lockres);
+			}
+			ocfs2_recover_from_dlm_error(lockres, 1);
+			goto out;
+		}
+		dlm_locked = 1;
+
+		mlog(0, "lock %s, successful return from ocfs2_dlm_lock\n",
+		     lockres->l_name);
+
+		/* At this point we've gone inside the dlm and need to
+		 * complete our work regardless. */
+		catch_signals = 0;
+
+		/* wait for busy to clear and carry on */
+		goto again;
+	}
+
+update_holders:
+	/* Ok, if we get here then we're good to go. */
+	ocfs2_inc_holders(lockres, level);
+
+	ret = 0;
+unlock:
+	lockres_clear_flags(lockres, OCFS2_LOCK_UPCONVERT_FINISHING);
+
+	/* ocfs2_unblock_lock reques on seeing OCFS2_LOCK_UPCONVERT_FINISHING */
+	kick_dc = (lockres->l_flags & OCFS2_LOCK_BLOCKED);
+
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+	if (kick_dc)
+		ocfs2_wake_downconvert_thread(osb);
+out:
+	/*
+	 * This is helping work around a lock inversion between the page lock
+	 * and dlm locks.  One path holds the page lock while calling aops
+	 * which block acquiring dlm locks.  The voting thread holds dlm
+	 * locks while acquiring page locks while down converting data locks.
+	 * This block is helping an aop path notice the inversion and back
+	 * off to unlock its page lock before trying the dlm lock again.
+	 */
+	if (wait && arg_flags & OCFS2_LOCK_NONBLOCK &&
+	    mw.mw_mask & (OCFS2_LOCK_BUSY|OCFS2_LOCK_BLOCKED)) {
+		wait = 0;
+		spin_lock_irqsave(&lockres->l_lock, flags);
+		if (__lockres_remove_mask_waiter(lockres, &mw)) {
+			if (dlm_locked)
+				lockres_or_flags(lockres,
+					OCFS2_LOCK_NONBLOCK_FINISHED);
+			spin_unlock_irqrestore(&lockres->l_lock, flags);
+			ret = -EAGAIN;
+		} else {
+			spin_unlock_irqrestore(&lockres->l_lock, flags);
+			goto again;
+		}
+	}
+	if (wait) {
+		ret = ocfs2_wait_for_mask(&mw);
+		if (ret == 0)
+			goto again;
+		mlog_errno(ret);
+	}
+	ocfs2_update_lock_stats(lockres, level, &mw, ret);
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (!ret && lockres->l_lockdep_map.key != NULL) {
+		if (level == DLM_LOCK_PR)
+			rwsem_acquire_read(&lockres->l_lockdep_map, l_subclass,
+				!!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
+				caller_ip);
+		else
+			rwsem_acquire(&lockres->l_lockdep_map, l_subclass,
+				!!(arg_flags & OCFS2_META_LOCK_NOQUEUE),
+				caller_ip);
+	}
+#endif
+	return ret;
+}
+
+static inline int ocfs2_cluster_lock(struct ocfs2_super *osb,
+				     struct ocfs2_lock_res *lockres,
+				     int level,
+				     u32 lkm_flags,
+				     int arg_flags)
+{
+	return __ocfs2_cluster_lock(osb, lockres, level, lkm_flags, arg_flags,
+				    0, _RET_IP_);
+}
+
+
+static void __ocfs2_cluster_unlock(struct ocfs2_super *osb,
+				   struct ocfs2_lock_res *lockres,
+				   int level,
+				   unsigned long caller_ip)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	ocfs2_dec_holders(lockres, level);
+	ocfs2_downconvert_on_unlock(osb, lockres);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	if (lockres->l_lockdep_map.key != NULL)
+		rwsem_release(&lockres->l_lockdep_map, caller_ip);
+#endif
+}
+
+static int ocfs2_create_new_lock(struct ocfs2_super *osb,
+				 struct ocfs2_lock_res *lockres,
+				 int ex,
+				 int local)
+{
+	int level =  ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	unsigned long flags;
+	u32 lkm_flags = local ? DLM_LKF_LOCAL : 0;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
+	lockres_or_flags(lockres, OCFS2_LOCK_LOCAL);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	return ocfs2_lock_create(osb, lockres, level, lkm_flags);
+}
+
+/* Grants us an EX lock on the data and metadata resources, skipping
+ * the normal cluster directory lookup. Use this ONLY on newly created
+ * inodes which other nodes can't possibly see, and which haven't been
+ * hashed in the inode hash yet. This can give us a good performance
+ * increase as it'll skip the network broadcast normally associated
+ * with creating a new lock resource. */
+int ocfs2_create_new_inode_locks(struct inode *inode)
+{
+	int ret;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	BUG_ON(!ocfs2_inode_is_new(inode));
+
+	mlog(0, "Inode %llu\n", (unsigned long long)OCFS2_I(inode)->ip_blkno);
+
+	/* NOTE: That we don't increment any of the holder counts, nor
+	 * do we add anything to a journal handle. Since this is
+	 * supposed to be a new inode which the cluster doesn't know
+	 * about yet, there is no need to.  As far as the LVB handling
+	 * is concerned, this is basically like acquiring an EX lock
+	 * on a resource which has an invalid one -- we'll set it
+	 * valid when we release the EX. */
+
+	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_rw_lockres, 1, 1);
+	if (ret) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	/*
+	 * We don't want to use DLM_LKF_LOCAL on a meta data lock as they
+	 * don't use a generation in their lock names.
+	 */
+	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_inode_lockres, 1, 0);
+	if (ret) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_open_lockres, 0, 0);
+	if (ret)
+		mlog_errno(ret);
+
+bail:
+	return ret;
+}
+
+int ocfs2_rw_lock(struct inode *inode, int write)
+{
+	int status, level;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu take %s RW lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	lockres = &OCFS2_I(inode)->ip_rw_lockres;
+
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
+	if (status < 0)
+		mlog_errno(status);
+
+	return status;
+}
+
+int ocfs2_try_rw_lock(struct inode *inode, int write)
+{
+	int status, level;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu try to take %s RW lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	lockres = &OCFS2_I(inode)->ip_rw_lockres;
+
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
+	return status;
+}
+
+void ocfs2_rw_unlock(struct inode *inode, int write)
+{
+	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu drop %s RW lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (!ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, level);
+}
+
+/*
+ * ocfs2_open_lock always get PR mode lock.
+ */
+int ocfs2_open_lock(struct inode *inode)
+{
+	int status = 0;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu take PRMODE open lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno);
+
+	if (ocfs2_is_hard_readonly(osb) || ocfs2_mount_local(osb))
+		goto out;
+
+	lockres = &OCFS2_I(inode)->ip_open_lockres;
+
+	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_PR, 0, 0);
+	if (status < 0)
+		mlog_errno(status);
+
+out:
+	return status;
+}
+
+int ocfs2_try_open_lock(struct inode *inode, int write)
+{
+	int status = 0, level;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu try to take %s open lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     write ? "EXMODE" : "PRMODE");
+
+	if (ocfs2_is_hard_readonly(osb)) {
+		if (write)
+			status = -EROFS;
+		goto out;
+	}
+
+	if (ocfs2_mount_local(osb))
+		goto out;
+
+	lockres = &OCFS2_I(inode)->ip_open_lockres;
+
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	/*
+	 * The file system may already holding a PRMODE/EXMODE open lock.
+	 * Since we pass DLM_LKF_NOQUEUE, the request won't block waiting on
+	 * other nodes and the -EAGAIN will indicate to the caller that
+	 * this inode is still in use.
+	 */
+	status = ocfs2_cluster_lock(osb, lockres, level, DLM_LKF_NOQUEUE, 0);
+
+out:
+	return status;
+}
+
+/*
+ * ocfs2_open_unlock unlock PR and EX mode open locks.
+ */
+void ocfs2_open_unlock(struct inode *inode)
+{
+	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_open_lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu drop open lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno);
+
+	if (ocfs2_mount_local(osb))
+		goto out;
+
+	if(lockres->l_ro_holders)
+		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_PR);
+	if(lockres->l_ex_holders)
+		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
+
+out:
+	return;
+}
+
+static int ocfs2_flock_handle_signal(struct ocfs2_lock_res *lockres,
+				     int level)
+{
+	int ret;
+	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
+	unsigned long flags;
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+retry_cancel:
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
+		ret = ocfs2_prepare_cancel_convert(osb, lockres);
+		if (ret) {
+			spin_unlock_irqrestore(&lockres->l_lock, flags);
+			ret = ocfs2_cancel_convert(osb, lockres);
+			if (ret < 0) {
+				mlog_errno(ret);
+				goto out;
+			}
+			goto retry_cancel;
+		}
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		ocfs2_wait_for_mask(&mw);
+		goto retry_cancel;
+	}
+
+	ret = -ERESTARTSYS;
+	/*
+	 * We may still have gotten the lock, in which case there's no
+	 * point to restarting the syscall.
+	 */
+	if (lockres->l_level == level)
+		ret = 0;
+
+	mlog(0, "Cancel returning %d. flags: 0x%lx, level: %d, act: %d\n", ret,
+	     lockres->l_flags, lockres->l_level, lockres->l_action);
+
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+out:
+	return ret;
+}
+
+/*
+ * ocfs2_file_lock() and ocfs2_file_unlock() map to a single pair of
+ * flock() calls. The locking approach this requires is sufficiently
+ * different from all other cluster lock types that we implement a
+ * separate path to the "low-level" dlm calls. In particular:
+ *
+ * - No optimization of lock levels is done - we take at exactly
+ *   what's been requested.
+ *
+ * - No lock caching is employed. We immediately downconvert to
+ *   no-lock at unlock time. This also means flock locks never go on
+ *   the blocking list).
+ *
+ * - Since userspace can trivially deadlock itself with flock, we make
+ *   sure to allow cancellation of a misbehaving applications flock()
+ *   request.
+ *
+ * - Access to any flock lockres doesn't require concurrency, so we
+ *   can simplify the code by requiring the caller to guarantee
+ *   serialization of dlmglue flock calls.
+ */
+int ocfs2_file_lock(struct file *file, int ex, int trylock)
+{
+	int ret, level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	unsigned int lkm_flags = trylock ? DLM_LKF_NOQUEUE : 0;
+	unsigned long flags;
+	struct ocfs2_file_private *fp = file->private_data;
+	struct ocfs2_lock_res *lockres = &fp->fp_flock;
+	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+	if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||
+	    (lockres->l_level > DLM_LOCK_NL)) {
+		mlog(ML_ERROR,
+		     "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
+		     "level: %u\n", lockres->l_name, lockres->l_flags,
+		     lockres->l_level);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		/*
+		 * Get the lock at NLMODE to start - that way we
+		 * can cancel the upconvert request if need be.
+		 */
+		ret = ocfs2_lock_create(osb, lockres, DLM_LOCK_NL, 0);
+		if (ret < 0) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		ret = ocfs2_wait_for_mask(&mw);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+		spin_lock_irqsave(&lockres->l_lock, flags);
+	}
+
+	lockres->l_action = OCFS2_AST_CONVERT;
+	lkm_flags |= DLM_LKF_CONVERT;
+	lockres->l_requested = level;
+	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+
+	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ret = ocfs2_dlm_lock(osb->cconn, level, &lockres->l_lksb, lkm_flags,
+			     lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1);
+	if (ret) {
+		if (!trylock || (ret != -EAGAIN)) {
+			ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
+			ret = -EINVAL;
+		}
+
+		ocfs2_recover_from_dlm_error(lockres, 1);
+		lockres_remove_mask_waiter(lockres, &mw);
+		goto out;
+	}
+
+	ret = ocfs2_wait_for_mask_interruptible(&mw, lockres);
+	if (ret == -ERESTARTSYS) {
+		/*
+		 * Userspace can cause deadlock itself with
+		 * flock(). Current behavior locally is to allow the
+		 * deadlock, but abort the system call if a signal is
+		 * received. We follow this example, otherwise a
+		 * poorly written program could sit in kernel until
+		 * reboot.
+		 *
+		 * Handling this is a bit more complicated for Ocfs2
+		 * though. We can't exit this function with an
+		 * outstanding lock request, so a cancel convert is
+		 * required. We intentionally overwrite 'ret' - if the
+		 * cancel fails and the lock was granted, it's easier
+		 * to just bubble success back up to the user.
+		 */
+		ret = ocfs2_flock_handle_signal(lockres, level);
+	} else if (!ret && (level > lockres->l_level)) {
+		/* Trylock failed asynchronously */
+		BUG_ON(!trylock);
+		ret = -EAGAIN;
+	}
+
+out:
+
+	mlog(0, "Lock: \"%s\" ex: %d, trylock: %d, returns: %d\n",
+	     lockres->l_name, ex, trylock, ret);
+	return ret;
+}
+
+void ocfs2_file_unlock(struct file *file)
+{
+	int ret;
+	unsigned int gen;
+	unsigned long flags;
+	struct ocfs2_file_private *fp = file->private_data;
+	struct ocfs2_lock_res *lockres = &fp->fp_flock;
+	struct ocfs2_super *osb = OCFS2_SB(file->f_mapping->host->i_sb);
+	struct ocfs2_mask_waiter mw;
+
+	ocfs2_init_mask_waiter(&mw);
+
+	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED))
+		return;
+
+	if (lockres->l_level == DLM_LOCK_NL)
+		return;
+
+	mlog(0, "Unlock: \"%s\" flags: 0x%lx, level: %d, act: %d\n",
+	     lockres->l_name, lockres->l_flags, lockres->l_level,
+	     lockres->l_action);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	/*
+	 * Fake a blocking ast for the downconvert code.
+	 */
+	lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
+	lockres->l_blocking = DLM_LOCK_EX;
+
+	gen = ocfs2_prepare_downconvert(lockres, DLM_LOCK_NL);
+	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ret = ocfs2_downconvert_lock(osb, lockres, DLM_LOCK_NL, 0, gen);
+	if (ret) {
+		mlog_errno(ret);
+		return;
+	}
+
+	ret = ocfs2_wait_for_mask(&mw);
+	if (ret)
+		mlog_errno(ret);
+}
+
+static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres)
+{
+	int kick = 0;
+
+	/* If we know that another node is waiting on our lock, kick
+	 * the downconvert thread * pre-emptively when we reach a release
+	 * condition. */
+	if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
+		switch(lockres->l_blocking) {
+		case DLM_LOCK_EX:
+			if (!lockres->l_ex_holders && !lockres->l_ro_holders)
+				kick = 1;
+			break;
+		case DLM_LOCK_PR:
+			if (!lockres->l_ex_holders)
+				kick = 1;
+			break;
+		default:
+			BUG();
+		}
+	}
+
+	if (kick)
+		ocfs2_wake_downconvert_thread(osb);
+}
+
+#define OCFS2_SEC_BITS   34
+#define OCFS2_SEC_SHIFT  (64 - OCFS2_SEC_BITS)
+#define OCFS2_NSEC_MASK  ((1ULL << OCFS2_SEC_SHIFT) - 1)
+
+/* LVB only has room for 64 bits of time here so we pack it for
+ * now. */
+static u64 ocfs2_pack_timespec(struct timespec64 *spec)
+{
+	u64 res;
+	u64 sec = clamp_t(time64_t, spec->tv_sec, 0, 0x3ffffffffull);
+	u32 nsec = spec->tv_nsec;
+
+	res = (sec << OCFS2_SEC_SHIFT) | (nsec & OCFS2_NSEC_MASK);
+
+	return res;
+}
+
+/* Call this with the lockres locked. I am reasonably sure we don't
+ * need ip_lock in this function as anyone who would be changing those
+ * values is supposed to be blocked in ocfs2_inode_lock right now. */
+static void __ocfs2_stuff_meta_lvb(struct inode *inode)
+{
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
+	struct ocfs2_meta_lvb *lvb;
+
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+
+	/*
+	 * Invalidate the LVB of a deleted inode - this way other
+	 * nodes are forced to go to disk and discover the new inode
+	 * status.
+	 */
+	if (oi->ip_flags & OCFS2_INODE_DELETED) {
+		lvb->lvb_version = 0;
+		goto out;
+	}
+
+	lvb->lvb_version   = OCFS2_LVB_VERSION;
+	lvb->lvb_isize	   = cpu_to_be64(i_size_read(inode));
+	lvb->lvb_iclusters = cpu_to_be32(oi->ip_clusters);
+	lvb->lvb_iuid      = cpu_to_be32(i_uid_read(inode));
+	lvb->lvb_igid      = cpu_to_be32(i_gid_read(inode));
+	lvb->lvb_imode     = cpu_to_be16(inode->i_mode);
+	lvb->lvb_inlink    = cpu_to_be16(inode->i_nlink);
+	lvb->lvb_iatime_packed  =
+		cpu_to_be64(ocfs2_pack_timespec(&inode->i_atime));
+	lvb->lvb_ictime_packed =
+		cpu_to_be64(ocfs2_pack_timespec(&inode->i_ctime));
+	lvb->lvb_imtime_packed =
+		cpu_to_be64(ocfs2_pack_timespec(&inode->i_mtime));
+	lvb->lvb_iattr    = cpu_to_be32(oi->ip_attr);
+	lvb->lvb_idynfeatures = cpu_to_be16(oi->ip_dyn_features);
+	lvb->lvb_igeneration = cpu_to_be32(inode->i_generation);
+
+out:
+	mlog_meta_lvb(0, lockres);
+}
+
+static void ocfs2_unpack_timespec(struct timespec64 *spec,
+				  u64 packed_time)
+{
+	spec->tv_sec = packed_time >> OCFS2_SEC_SHIFT;
+	spec->tv_nsec = packed_time & OCFS2_NSEC_MASK;
+}
+
+static int ocfs2_refresh_inode_from_lvb(struct inode *inode)
+{
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
+	struct ocfs2_meta_lvb *lvb;
+
+	mlog_meta_lvb(0, lockres);
+
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	if (inode_wrong_type(inode, be16_to_cpu(lvb->lvb_imode)))
+		return -ESTALE;
+
+	/* We're safe here without the lockres lock... */
+	spin_lock(&oi->ip_lock);
+	oi->ip_clusters = be32_to_cpu(lvb->lvb_iclusters);
+	i_size_write(inode, be64_to_cpu(lvb->lvb_isize));
+
+	oi->ip_attr = be32_to_cpu(lvb->lvb_iattr);
+	oi->ip_dyn_features = be16_to_cpu(lvb->lvb_idynfeatures);
+	ocfs2_set_inode_flags(inode);
+
+	/* fast-symlinks are a special case */
+	if (S_ISLNK(inode->i_mode) && !oi->ip_clusters)
+		inode->i_blocks = 0;
+	else
+		inode->i_blocks = ocfs2_inode_sector_count(inode);
+
+	i_uid_write(inode, be32_to_cpu(lvb->lvb_iuid));
+	i_gid_write(inode, be32_to_cpu(lvb->lvb_igid));
+	inode->i_mode    = be16_to_cpu(lvb->lvb_imode);
+	set_nlink(inode, be16_to_cpu(lvb->lvb_inlink));
+	ocfs2_unpack_timespec(&inode->i_atime,
+			      be64_to_cpu(lvb->lvb_iatime_packed));
+	ocfs2_unpack_timespec(&inode->i_mtime,
+			      be64_to_cpu(lvb->lvb_imtime_packed));
+	ocfs2_unpack_timespec(&inode->i_ctime,
+			      be64_to_cpu(lvb->lvb_ictime_packed));
+	spin_unlock(&oi->ip_lock);
+	return 0;
+}
+
+static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
+					      struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_meta_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+
+	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)
+	    && lvb->lvb_version == OCFS2_LVB_VERSION
+	    && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)
+		return 1;
+	return 0;
+}
+
+/* Determine whether a lock resource needs to be refreshed, and
+ * arbitrate who gets to refresh it.
+ *
+ *   0 means no refresh needed.
+ *
+ *   > 0 means you need to refresh this and you MUST call
+ *   ocfs2_complete_lock_res_refresh afterwards. */
+static int ocfs2_should_refresh_lock_res(struct ocfs2_lock_res *lockres)
+{
+	unsigned long flags;
+	int status = 0;
+
+refresh_check:
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (!(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH)) {
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		goto bail;
+	}
+
+	if (lockres->l_flags & OCFS2_LOCK_REFRESHING) {
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		ocfs2_wait_on_refreshing_lock(lockres);
+		goto refresh_check;
+	}
+
+	/* Ok, I'll be the one to refresh this lock. */
+	lockres_or_flags(lockres, OCFS2_LOCK_REFRESHING);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	status = 1;
+bail:
+	mlog(0, "status %d\n", status);
+	return status;
+}
+
+/* If status is non zero, I'll mark it as not being in refresh
+ * anymroe, but i won't clear the needs refresh flag. */
+static inline void ocfs2_complete_lock_res_refresh(struct ocfs2_lock_res *lockres,
+						   int status)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	lockres_clear_flags(lockres, OCFS2_LOCK_REFRESHING);
+	if (!status)
+		lockres_clear_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	wake_up(&lockres->l_event);
+}
+
+/* may or may not return a bh if it went to disk. */
+static int ocfs2_inode_lock_update(struct inode *inode,
+				  struct buffer_head **bh)
+{
+	int status = 0;
+	struct ocfs2_inode_info *oi = OCFS2_I(inode);
+	struct ocfs2_lock_res *lockres = &oi->ip_inode_lockres;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	if (ocfs2_mount_local(osb))
+		goto bail;
+
+	spin_lock(&oi->ip_lock);
+	if (oi->ip_flags & OCFS2_INODE_DELETED) {
+		mlog(0, "Orphaned inode %llu was deleted while we "
+		     "were waiting on a lock. ip_flags = 0x%x\n",
+		     (unsigned long long)oi->ip_blkno, oi->ip_flags);
+		spin_unlock(&oi->ip_lock);
+		status = -ENOENT;
+		goto bail;
+	}
+	spin_unlock(&oi->ip_lock);
+
+	if (!ocfs2_should_refresh_lock_res(lockres))
+		goto bail;
+
+	/* This will discard any caching information we might have had
+	 * for the inode metadata. */
+	ocfs2_metadata_cache_purge(INODE_CACHE(inode));
+
+	ocfs2_extent_map_trunc(inode, 0);
+
+	if (ocfs2_meta_lvb_is_trustable(inode, lockres)) {
+		mlog(0, "Trusting LVB on inode %llu\n",
+		     (unsigned long long)oi->ip_blkno);
+		status = ocfs2_refresh_inode_from_lvb(inode);
+		goto bail_refresh;
+	} else {
+		/* Boo, we have to go to disk. */
+		/* read bh, cast, ocfs2_refresh_inode */
+		status = ocfs2_read_inode_block(inode, bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail_refresh;
+		}
+		fe = (struct ocfs2_dinode *) (*bh)->b_data;
+		if (inode_wrong_type(inode, le16_to_cpu(fe->i_mode))) {
+			status = -ESTALE;
+			goto bail_refresh;
+		}
+
+		/* This is a good chance to make sure we're not
+		 * locking an invalid object.  ocfs2_read_inode_block()
+		 * already checked that the inode block is sane.
+		 *
+		 * We bug on a stale inode here because we checked
+		 * above whether it was wiped from disk. The wiping
+		 * node provides a guarantee that we receive that
+		 * message and can mark the inode before dropping any
+		 * locks associated with it. */
+		mlog_bug_on_msg(inode->i_generation !=
+				le32_to_cpu(fe->i_generation),
+				"Invalid dinode %llu disk generation: %u "
+				"inode->i_generation: %u\n",
+				(unsigned long long)oi->ip_blkno,
+				le32_to_cpu(fe->i_generation),
+				inode->i_generation);
+		mlog_bug_on_msg(le64_to_cpu(fe->i_dtime) ||
+				!(fe->i_flags & cpu_to_le32(OCFS2_VALID_FL)),
+				"Stale dinode %llu dtime: %llu flags: 0x%x\n",
+				(unsigned long long)oi->ip_blkno,
+				(unsigned long long)le64_to_cpu(fe->i_dtime),
+				le32_to_cpu(fe->i_flags));
+
+		ocfs2_refresh_inode(inode, fe);
+		ocfs2_track_lock_refresh(lockres);
+	}
+
+	status = 0;
+bail_refresh:
+	ocfs2_complete_lock_res_refresh(lockres, status);
+bail:
+	return status;
+}
+
+static int ocfs2_assign_bh(struct inode *inode,
+			   struct buffer_head **ret_bh,
+			   struct buffer_head *passed_bh)
+{
+	int status;
+
+	if (passed_bh) {
+		/* Ok, the update went to disk for us, use the
+		 * returned bh. */
+		*ret_bh = passed_bh;
+		get_bh(*ret_bh);
+
+		return 0;
+	}
+
+	status = ocfs2_read_inode_block(inode, ret_bh);
+	if (status < 0)
+		mlog_errno(status);
+
+	return status;
+}
+
+/*
+ * returns < 0 error if the callback will never be called, otherwise
+ * the result of the lock will be communicated via the callback.
+ */
+int ocfs2_inode_lock_full_nested(struct inode *inode,
+				 struct buffer_head **ret_bh,
+				 int ex,
+				 int arg_flags,
+				 int subclass)
+{
+	int status, level, acquired;
+	u32 dlm_flags;
+	struct ocfs2_lock_res *lockres = NULL;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+	struct buffer_head *local_bh = NULL;
+
+	mlog(0, "inode %llu, take %s META lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     ex ? "EXMODE" : "PRMODE");
+
+	status = 0;
+	acquired = 0;
+	/* We'll allow faking a readonly metadata lock for
+	 * rodevices. */
+	if (ocfs2_is_hard_readonly(osb)) {
+		if (ex)
+			status = -EROFS;
+		goto getbh;
+	}
+
+	if ((arg_flags & OCFS2_META_LOCK_GETBH) ||
+	    ocfs2_mount_local(osb))
+		goto update;
+
+	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
+		ocfs2_wait_for_recovery(osb);
+
+	lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	dlm_flags = 0;
+	if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
+		dlm_flags |= DLM_LKF_NOQUEUE;
+
+	status = __ocfs2_cluster_lock(osb, lockres, level, dlm_flags,
+				      arg_flags, subclass, _RET_IP_);
+	if (status < 0) {
+		if (status != -EAGAIN)
+			mlog_errno(status);
+		goto bail;
+	}
+
+	/* Notify the error cleanup path to drop the cluster lock. */
+	acquired = 1;
+
+	/* We wait twice because a node may have died while we were in
+	 * the lower dlm layers. The second time though, we've
+	 * committed to owning this lock so we don't allow signals to
+	 * abort the operation. */
+	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
+		ocfs2_wait_for_recovery(osb);
+
+update:
+	/*
+	 * We only see this flag if we're being called from
+	 * ocfs2_read_locked_inode(). It means we're locking an inode
+	 * which hasn't been populated yet, so clear the refresh flag
+	 * and let the caller handle it.
+	 */
+	if (inode->i_state & I_NEW) {
+		status = 0;
+		if (lockres)
+			ocfs2_complete_lock_res_refresh(lockres, 0);
+		goto bail;
+	}
+
+	/* This is fun. The caller may want a bh back, or it may
+	 * not. ocfs2_inode_lock_update definitely wants one in, but
+	 * may or may not read one, depending on what's in the
+	 * LVB. The result of all of this is that we've *only* gone to
+	 * disk if we have to, so the complexity is worthwhile. */
+	status = ocfs2_inode_lock_update(inode, &local_bh);
+	if (status < 0) {
+		if (status != -ENOENT)
+			mlog_errno(status);
+		goto bail;
+	}
+getbh:
+	if (ret_bh) {
+		status = ocfs2_assign_bh(inode, ret_bh, local_bh);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+	}
+
+bail:
+	if (status < 0) {
+		if (ret_bh && (*ret_bh)) {
+			brelse(*ret_bh);
+			*ret_bh = NULL;
+		}
+		if (acquired)
+			ocfs2_inode_unlock(inode, ex);
+	}
+
+	brelse(local_bh);
+	return status;
+}
+
+/*
+ * This is working around a lock inversion between tasks acquiring DLM
+ * locks while holding a page lock and the downconvert thread which
+ * blocks dlm lock acquiry while acquiring page locks.
+ *
+ * ** These _with_page variantes are only intended to be called from aop
+ * methods that hold page locks and return a very specific *positive* error
+ * code that aop methods pass up to the VFS -- test for errors with != 0. **
+ *
+ * The DLM is called such that it returns -EAGAIN if it would have
+ * blocked waiting for the downconvert thread.  In that case we unlock
+ * our page so the downconvert thread can make progress.  Once we've
+ * done this we have to return AOP_TRUNCATED_PAGE so the aop method
+ * that called us can bubble that back up into the VFS who will then
+ * immediately retry the aop call.
+ */
+int ocfs2_inode_lock_with_page(struct inode *inode,
+			      struct buffer_head **ret_bh,
+			      int ex,
+			      struct page *page)
+{
+	int ret;
+
+	ret = ocfs2_inode_lock_full(inode, ret_bh, ex, OCFS2_LOCK_NONBLOCK);
+	if (ret == -EAGAIN) {
+		unlock_page(page);
+		/*
+		 * If we can't get inode lock immediately, we should not return
+		 * directly here, since this will lead to a softlockup problem.
+		 * The method is to get a blocking lock and immediately unlock
+		 * before returning, this can avoid CPU resource waste due to
+		 * lots of retries, and benefits fairness in getting lock.
+		 */
+		if (ocfs2_inode_lock(inode, ret_bh, ex) == 0)
+			ocfs2_inode_unlock(inode, ex);
+		ret = AOP_TRUNCATED_PAGE;
+	}
+
+	return ret;
+}
+
+int ocfs2_inode_lock_atime(struct inode *inode,
+			  struct vfsmount *vfsmnt,
+			  int *level, int wait)
+{
+	int ret;
+
+	if (wait)
+		ret = ocfs2_inode_lock(inode, NULL, 0);
+	else
+		ret = ocfs2_try_inode_lock(inode, NULL, 0);
+
+	if (ret < 0) {
+		if (ret != -EAGAIN)
+			mlog_errno(ret);
+		return ret;
+	}
+
+	/*
+	 * If we should update atime, we will get EX lock,
+	 * otherwise we just get PR lock.
+	 */
+	if (ocfs2_should_update_atime(inode, vfsmnt)) {
+		struct buffer_head *bh = NULL;
+
+		ocfs2_inode_unlock(inode, 0);
+		if (wait)
+			ret = ocfs2_inode_lock(inode, &bh, 1);
+		else
+			ret = ocfs2_try_inode_lock(inode, &bh, 1);
+
+		if (ret < 0) {
+			if (ret != -EAGAIN)
+				mlog_errno(ret);
+			return ret;
+		}
+		*level = 1;
+		if (ocfs2_should_update_atime(inode, vfsmnt))
+			ocfs2_update_inode_atime(inode, bh);
+		brelse(bh);
+	} else
+		*level = 0;
+
+	return ret;
+}
+
+void ocfs2_inode_unlock(struct inode *inode,
+		       int ex)
+{
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+	mlog(0, "inode %llu drop %s META lock\n",
+	     (unsigned long long)OCFS2_I(inode)->ip_blkno,
+	     ex ? "EXMODE" : "PRMODE");
+
+	if (!ocfs2_is_hard_readonly(osb) &&
+	    !ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, level);
+}
+
+/*
+ * This _tracker variantes are introduced to deal with the recursive cluster
+ * locking issue. The idea is to keep track of a lock holder on the stack of
+ * the current process. If there's a lock holder on the stack, we know the
+ * task context is already protected by cluster locking. Currently, they're
+ * used in some VFS entry routines.
+ *
+ * return < 0 on error, return == 0 if there's no lock holder on the stack
+ * before this call, return == 1 if this call would be a recursive locking.
+ * return == -1 if this lock attempt will cause an upgrade which is forbidden.
+ *
+ * When taking lock levels into account,we face some different situations.
+ *
+ * 1. no lock is held
+ *    In this case, just lock the inode as requested and return 0
+ *
+ * 2. We are holding a lock
+ *    For this situation, things diverges into several cases
+ *
+ *    wanted     holding	     what to do
+ *    ex		ex	    see 2.1 below
+ *    ex		pr	    see 2.2 below
+ *    pr		ex	    see 2.1 below
+ *    pr		pr	    see 2.1 below
+ *
+ *    2.1 lock level that is been held is compatible
+ *    with the wanted level, so no lock action will be tacken.
+ *
+ *    2.2 Otherwise, an upgrade is needed, but it is forbidden.
+ *
+ * Reason why upgrade within a process is forbidden is that
+ * lock upgrade may cause dead lock. The following illustrates
+ * how it happens.
+ *
+ *         thread on node1                             thread on node2
+ * ocfs2_inode_lock_tracker(ex=0)
+ *
+ *                                <======   ocfs2_inode_lock_tracker(ex=1)
+ *
+ * ocfs2_inode_lock_tracker(ex=1)
+ */
+int ocfs2_inode_lock_tracker(struct inode *inode,
+			     struct buffer_head **ret_bh,
+			     int ex,
+			     struct ocfs2_lock_holder *oh)
+{
+	int status = 0;
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_lock_holder *tmp_oh;
+	struct pid *pid = task_pid(current);
+
+
+	lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	tmp_oh = ocfs2_pid_holder(lockres, pid);
+
+	if (!tmp_oh) {
+		/*
+		 * This corresponds to the case 1.
+		 * We haven't got any lock before.
+		 */
+		status = ocfs2_inode_lock_full(inode, ret_bh, ex, 0);
+		if (status < 0) {
+			if (status != -ENOENT)
+				mlog_errno(status);
+			return status;
+		}
+
+		oh->oh_ex = ex;
+		ocfs2_add_holder(lockres, oh);
+		return 0;
+	}
+
+	if (unlikely(ex && !tmp_oh->oh_ex)) {
+		/*
+		 * case 2.2 upgrade may cause dead lock, forbid it.
+		 */
+		mlog(ML_ERROR, "Recursive locking is not permitted to "
+		     "upgrade to EX level from PR level.\n");
+		dump_stack();
+		return -EINVAL;
+	}
+
+	/*
+	 *  case 2.1 OCFS2_META_LOCK_GETBH flag make ocfs2_inode_lock_full.
+	 *  ignore the lock level and just update it.
+	 */
+	if (ret_bh) {
+		status = ocfs2_inode_lock_full(inode, ret_bh, ex,
+					       OCFS2_META_LOCK_GETBH);
+		if (status < 0) {
+			if (status != -ENOENT)
+				mlog_errno(status);
+			return status;
+		}
+	}
+	return 1;
+}
+
+void ocfs2_inode_unlock_tracker(struct inode *inode,
+				int ex,
+				struct ocfs2_lock_holder *oh,
+				int had_lock)
+{
+	struct ocfs2_lock_res *lockres;
+
+	lockres = &OCFS2_I(inode)->ip_inode_lockres;
+	/* had_lock means that the currect process already takes the cluster
+	 * lock previously.
+	 * If had_lock is 1, we have nothing to do here.
+	 * If had_lock is 0, we will release the lock.
+	 */
+	if (!had_lock) {
+		ocfs2_inode_unlock(inode, oh->oh_ex);
+		ocfs2_remove_holder(lockres, oh);
+	}
+}
+
+int ocfs2_orphan_scan_lock(struct ocfs2_super *osb, u32 *seqno)
+{
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_orphan_scan_lvb *lvb;
+	int status = 0;
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	lockres = &osb->osb_orphan_scan.os_lockres;
+	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);
+	if (status < 0)
+		return status;
+
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
+	    lvb->lvb_version == OCFS2_ORPHAN_LVB_VERSION)
+		*seqno = be32_to_cpu(lvb->lvb_os_seqno);
+	else
+		*seqno = osb->osb_orphan_scan.os_seqno + 1;
+
+	return status;
+}
+
+void ocfs2_orphan_scan_unlock(struct ocfs2_super *osb, u32 seqno)
+{
+	struct ocfs2_lock_res *lockres;
+	struct ocfs2_orphan_scan_lvb *lvb;
+
+	if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb)) {
+		lockres = &osb->osb_orphan_scan.os_lockres;
+		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+		lvb->lvb_version = OCFS2_ORPHAN_LVB_VERSION;
+		lvb->lvb_os_seqno = cpu_to_be32(seqno);
+		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
+	}
+}
+
+int ocfs2_super_lock(struct ocfs2_super *osb,
+		     int ex)
+{
+	int status = 0;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ocfs2_mount_local(osb))
+		goto bail;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* The super block lock path is really in the best position to
+	 * know when resources covered by the lock need to be
+	 * refreshed, so we do it here. Of course, making sense of
+	 * everything is up to the caller :) */
+	status = ocfs2_should_refresh_lock_res(lockres);
+	if (status) {
+		status = ocfs2_refresh_slot_info(osb);
+
+		ocfs2_complete_lock_res_refresh(lockres, status);
+
+		if (status < 0) {
+			ocfs2_cluster_unlock(osb, lockres, level);
+			mlog_errno(status);
+		}
+		ocfs2_track_lock_refresh(lockres);
+	}
+bail:
+	return status;
+}
+
+void ocfs2_super_unlock(struct ocfs2_super *osb,
+			int ex)
+{
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
+
+	if (!ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, level);
+}
+
+int ocfs2_rename_lock(struct ocfs2_super *osb)
+{
+	int status;
+	struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);
+	if (status < 0)
+		mlog_errno(status);
+
+	return status;
+}
+
+void ocfs2_rename_unlock(struct ocfs2_super *osb)
+{
+	struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
+
+	if (!ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
+}
+
+int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex)
+{
+	int status;
+	struct ocfs2_lock_res *lockres = &osb->osb_nfs_sync_lockres;
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ex)
+		down_write(&osb->nfs_sync_rwlock);
+	else
+		down_read(&osb->nfs_sync_rwlock);
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	status = ocfs2_cluster_lock(osb, lockres, ex ? LKM_EXMODE : LKM_PRMODE,
+				    0, 0);
+	if (status < 0) {
+		mlog(ML_ERROR, "lock on nfs sync lock failed %d\n", status);
+
+		if (ex)
+			up_write(&osb->nfs_sync_rwlock);
+		else
+			up_read(&osb->nfs_sync_rwlock);
+	}
+
+	return status;
+}
+
+void ocfs2_nfs_sync_unlock(struct ocfs2_super *osb, int ex)
+{
+	struct ocfs2_lock_res *lockres = &osb->osb_nfs_sync_lockres;
+
+	if (!ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres,
+				     ex ? LKM_EXMODE : LKM_PRMODE);
+	if (ex)
+		up_write(&osb->nfs_sync_rwlock);
+	else
+		up_read(&osb->nfs_sync_rwlock);
+}
+
+int ocfs2_trim_fs_lock(struct ocfs2_super *osb,
+		       struct ocfs2_trim_fs_info *info, int trylock)
+{
+	int status;
+	struct ocfs2_trim_fs_lvb *lvb;
+	struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
+
+	if (info)
+		info->tf_valid = 0;
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX,
+				    trylock ? DLM_LKF_NOQUEUE : 0, 0);
+	if (status < 0) {
+		if (status != -EAGAIN)
+			mlog_errno(status);
+		return status;
+	}
+
+	if (info) {
+		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+		if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
+		    lvb->lvb_version == OCFS2_TRIMFS_LVB_VERSION) {
+			info->tf_valid = 1;
+			info->tf_success = lvb->lvb_success;
+			info->tf_nodenum = be32_to_cpu(lvb->lvb_nodenum);
+			info->tf_start = be64_to_cpu(lvb->lvb_start);
+			info->tf_len = be64_to_cpu(lvb->lvb_len);
+			info->tf_minlen = be64_to_cpu(lvb->lvb_minlen);
+			info->tf_trimlen = be64_to_cpu(lvb->lvb_trimlen);
+		}
+	}
+
+	return status;
+}
+
+void ocfs2_trim_fs_unlock(struct ocfs2_super *osb,
+			  struct ocfs2_trim_fs_info *info)
+{
+	struct ocfs2_trim_fs_lvb *lvb;
+	struct ocfs2_lock_res *lockres = &osb->osb_trim_fs_lockres;
+
+	if (ocfs2_mount_local(osb))
+		return;
+
+	if (info) {
+		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+		lvb->lvb_version = OCFS2_TRIMFS_LVB_VERSION;
+		lvb->lvb_success = info->tf_success;
+		lvb->lvb_nodenum = cpu_to_be32(info->tf_nodenum);
+		lvb->lvb_start = cpu_to_be64(info->tf_start);
+		lvb->lvb_len = cpu_to_be64(info->tf_len);
+		lvb->lvb_minlen = cpu_to_be64(info->tf_minlen);
+		lvb->lvb_trimlen = cpu_to_be64(info->tf_trimlen);
+	}
+
+	ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
+}
+
+int ocfs2_dentry_lock(struct dentry *dentry, int ex)
+{
+	int ret;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
+	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
+
+	BUG_ON(!dl);
+
+	if (ocfs2_is_hard_readonly(osb)) {
+		if (ex)
+			return -EROFS;
+		return 0;
+	}
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	ret = ocfs2_cluster_lock(osb, &dl->dl_lockres, level, 0, 0);
+	if (ret < 0)
+		mlog_errno(ret);
+
+	return ret;
+}
+
+void ocfs2_dentry_unlock(struct dentry *dentry, int ex)
+{
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
+	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
+
+	if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, &dl->dl_lockres, level);
+}
+
+/* Reference counting of the dlm debug structure. We want this because
+ * open references on the debug inodes can live on after a mount, so
+ * we can't rely on the ocfs2_super to always exist. */
+static void ocfs2_dlm_debug_free(struct kref *kref)
+{
+	struct ocfs2_dlm_debug *dlm_debug;
+
+	dlm_debug = container_of(kref, struct ocfs2_dlm_debug, d_refcnt);
+
+	kfree(dlm_debug);
+}
+
+void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug)
+{
+	if (dlm_debug)
+		kref_put(&dlm_debug->d_refcnt, ocfs2_dlm_debug_free);
+}
+
+static void ocfs2_get_dlm_debug(struct ocfs2_dlm_debug *debug)
+{
+	kref_get(&debug->d_refcnt);
+}
+
+struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void)
+{
+	struct ocfs2_dlm_debug *dlm_debug;
+
+	dlm_debug = kmalloc(sizeof(struct ocfs2_dlm_debug), GFP_KERNEL);
+	if (!dlm_debug) {
+		mlog_errno(-ENOMEM);
+		goto out;
+	}
+
+	kref_init(&dlm_debug->d_refcnt);
+	INIT_LIST_HEAD(&dlm_debug->d_lockres_tracking);
+	dlm_debug->d_filter_secs = 0;
+out:
+	return dlm_debug;
+}
+
+/* Access to this is arbitrated for us via seq_file->sem. */
+struct ocfs2_dlm_seq_priv {
+	struct ocfs2_dlm_debug *p_dlm_debug;
+	struct ocfs2_lock_res p_iter_res;
+	struct ocfs2_lock_res p_tmp_res;
+};
+
+static struct ocfs2_lock_res *ocfs2_dlm_next_res(struct ocfs2_lock_res *start,
+						 struct ocfs2_dlm_seq_priv *priv)
+{
+	struct ocfs2_lock_res *iter, *ret = NULL;
+	struct ocfs2_dlm_debug *dlm_debug = priv->p_dlm_debug;
+
+	assert_spin_locked(&ocfs2_dlm_tracking_lock);
+
+	list_for_each_entry(iter, &start->l_debug_list, l_debug_list) {
+		/* discover the head of the list */
+		if (&iter->l_debug_list == &dlm_debug->d_lockres_tracking) {
+			mlog(0, "End of list found, %p\n", ret);
+			break;
+		}
+
+		/* We track our "dummy" iteration lockres' by a NULL
+		 * l_ops field. */
+		if (iter->l_ops != NULL) {
+			ret = iter;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void *ocfs2_dlm_seq_start(struct seq_file *m, loff_t *pos)
+{
+	struct ocfs2_dlm_seq_priv *priv = m->private;
+	struct ocfs2_lock_res *iter;
+
+	spin_lock(&ocfs2_dlm_tracking_lock);
+	iter = ocfs2_dlm_next_res(&priv->p_iter_res, priv);
+	if (iter) {
+		/* Since lockres' have the lifetime of their container
+		 * (which can be inodes, ocfs2_supers, etc) we want to
+		 * copy this out to a temporary lockres while still
+		 * under the spinlock. Obviously after this we can't
+		 * trust any pointers on the copy returned, but that's
+		 * ok as the information we want isn't typically held
+		 * in them. */
+		priv->p_tmp_res = *iter;
+		iter = &priv->p_tmp_res;
+	}
+	spin_unlock(&ocfs2_dlm_tracking_lock);
+
+	return iter;
+}
+
+static void ocfs2_dlm_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static void *ocfs2_dlm_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct ocfs2_dlm_seq_priv *priv = m->private;
+	struct ocfs2_lock_res *iter = v;
+	struct ocfs2_lock_res *dummy = &priv->p_iter_res;
+
+	spin_lock(&ocfs2_dlm_tracking_lock);
+	iter = ocfs2_dlm_next_res(iter, priv);
+	list_del_init(&dummy->l_debug_list);
+	if (iter) {
+		list_add(&dummy->l_debug_list, &iter->l_debug_list);
+		priv->p_tmp_res = *iter;
+		iter = &priv->p_tmp_res;
+	}
+	spin_unlock(&ocfs2_dlm_tracking_lock);
+
+	return iter;
+}
+
+/*
+ * Version is used by debugfs.ocfs2 to determine the format being used
+ *
+ * New in version 2
+ *	- Lock stats printed
+ * New in version 3
+ *	- Max time in lock stats is in usecs (instead of nsecs)
+ * New in version 4
+ *	- Add last pr/ex unlock times and first lock wait time in usecs
+ */
+#define OCFS2_DLM_DEBUG_STR_VERSION 4
+static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
+{
+	int i;
+	char *lvb;
+	struct ocfs2_lock_res *lockres = v;
+#ifdef CONFIG_OCFS2_FS_STATS
+	u64 now, last;
+	struct ocfs2_dlm_debug *dlm_debug =
+			((struct ocfs2_dlm_seq_priv *)m->private)->p_dlm_debug;
+#endif
+
+	if (!lockres)
+		return -EINVAL;
+
+#ifdef CONFIG_OCFS2_FS_STATS
+	if (!lockres->l_lock_wait && dlm_debug->d_filter_secs) {
+		now = ktime_to_us(ktime_get_real());
+		if (lockres->l_lock_prmode.ls_last >
+		    lockres->l_lock_exmode.ls_last)
+			last = lockres->l_lock_prmode.ls_last;
+		else
+			last = lockres->l_lock_exmode.ls_last;
+		/*
+		 * Use d_filter_secs field to filter lock resources dump,
+		 * the default d_filter_secs(0) value filters nothing,
+		 * otherwise, only dump the last N seconds active lock
+		 * resources.
+		 */
+		if (div_u64(now - last, 1000000) > dlm_debug->d_filter_secs)
+			return 0;
+	}
+#endif
+
+	seq_printf(m, "0x%x\t", OCFS2_DLM_DEBUG_STR_VERSION);
+
+	if (lockres->l_type == OCFS2_LOCK_TYPE_DENTRY)
+		seq_printf(m, "%.*s%08x\t", OCFS2_DENTRY_LOCK_INO_START - 1,
+			   lockres->l_name,
+			   (unsigned int)ocfs2_get_dentry_lock_ino(lockres));
+	else
+		seq_printf(m, "%.*s\t", OCFS2_LOCK_ID_MAX_LEN, lockres->l_name);
+
+	seq_printf(m, "%d\t"
+		   "0x%lx\t"
+		   "0x%x\t"
+		   "0x%x\t"
+		   "%u\t"
+		   "%u\t"
+		   "%d\t"
+		   "%d\t",
+		   lockres->l_level,
+		   lockres->l_flags,
+		   lockres->l_action,
+		   lockres->l_unlock_action,
+		   lockres->l_ro_holders,
+		   lockres->l_ex_holders,
+		   lockres->l_requested,
+		   lockres->l_blocking);
+
+	/* Dump the raw LVB */
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	for(i = 0; i < DLM_LVB_LEN; i++)
+		seq_printf(m, "0x%x\t", lvb[i]);
+
+#ifdef CONFIG_OCFS2_FS_STATS
+# define lock_num_prmode(_l)		((_l)->l_lock_prmode.ls_gets)
+# define lock_num_exmode(_l)		((_l)->l_lock_exmode.ls_gets)
+# define lock_num_prmode_failed(_l)	((_l)->l_lock_prmode.ls_fail)
+# define lock_num_exmode_failed(_l)	((_l)->l_lock_exmode.ls_fail)
+# define lock_total_prmode(_l)		((_l)->l_lock_prmode.ls_total)
+# define lock_total_exmode(_l)		((_l)->l_lock_exmode.ls_total)
+# define lock_max_prmode(_l)		((_l)->l_lock_prmode.ls_max)
+# define lock_max_exmode(_l)		((_l)->l_lock_exmode.ls_max)
+# define lock_refresh(_l)		((_l)->l_lock_refresh)
+# define lock_last_prmode(_l)		((_l)->l_lock_prmode.ls_last)
+# define lock_last_exmode(_l)		((_l)->l_lock_exmode.ls_last)
+# define lock_wait(_l)			((_l)->l_lock_wait)
+#else
+# define lock_num_prmode(_l)		(0)
+# define lock_num_exmode(_l)		(0)
+# define lock_num_prmode_failed(_l)	(0)
+# define lock_num_exmode_failed(_l)	(0)
+# define lock_total_prmode(_l)		(0ULL)
+# define lock_total_exmode(_l)		(0ULL)
+# define lock_max_prmode(_l)		(0)
+# define lock_max_exmode(_l)		(0)
+# define lock_refresh(_l)		(0)
+# define lock_last_prmode(_l)		(0ULL)
+# define lock_last_exmode(_l)		(0ULL)
+# define lock_wait(_l)			(0ULL)
+#endif
+	/* The following seq_print was added in version 2 of this output */
+	seq_printf(m, "%u\t"
+		   "%u\t"
+		   "%u\t"
+		   "%u\t"
+		   "%llu\t"
+		   "%llu\t"
+		   "%u\t"
+		   "%u\t"
+		   "%u\t"
+		   "%llu\t"
+		   "%llu\t"
+		   "%llu\t",
+		   lock_num_prmode(lockres),
+		   lock_num_exmode(lockres),
+		   lock_num_prmode_failed(lockres),
+		   lock_num_exmode_failed(lockres),
+		   lock_total_prmode(lockres),
+		   lock_total_exmode(lockres),
+		   lock_max_prmode(lockres),
+		   lock_max_exmode(lockres),
+		   lock_refresh(lockres),
+		   lock_last_prmode(lockres),
+		   lock_last_exmode(lockres),
+		   lock_wait(lockres));
+
+	/* End the line */
+	seq_printf(m, "\n");
+	return 0;
+}
+
+static const struct seq_operations ocfs2_dlm_seq_ops = {
+	.start =	ocfs2_dlm_seq_start,
+	.stop =		ocfs2_dlm_seq_stop,
+	.next =		ocfs2_dlm_seq_next,
+	.show =		ocfs2_dlm_seq_show,
+};
+
+static int ocfs2_dlm_debug_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+	struct ocfs2_dlm_seq_priv *priv = seq->private;
+	struct ocfs2_lock_res *res = &priv->p_iter_res;
+
+	ocfs2_remove_lockres_tracking(res);
+	ocfs2_put_dlm_debug(priv->p_dlm_debug);
+	return seq_release_private(inode, file);
+}
+
+static int ocfs2_dlm_debug_open(struct inode *inode, struct file *file)
+{
+	struct ocfs2_dlm_seq_priv *priv;
+	struct ocfs2_super *osb;
+
+	priv = __seq_open_private(file, &ocfs2_dlm_seq_ops, sizeof(*priv));
+	if (!priv) {
+		mlog_errno(-ENOMEM);
+		return -ENOMEM;
+	}
+
+	osb = inode->i_private;
+	ocfs2_get_dlm_debug(osb->osb_dlm_debug);
+	priv->p_dlm_debug = osb->osb_dlm_debug;
+	INIT_LIST_HEAD(&priv->p_iter_res.l_debug_list);
+
+	ocfs2_add_lockres_tracking(&priv->p_iter_res,
+				   priv->p_dlm_debug);
+
+	return 0;
+}
+
+static const struct file_operations ocfs2_dlm_debug_fops = {
+	.open =		ocfs2_dlm_debug_open,
+	.release =	ocfs2_dlm_debug_release,
+	.read =		seq_read,
+	.llseek =	seq_lseek,
+};
+
+static void ocfs2_dlm_init_debug(struct ocfs2_super *osb)
+{
+	struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
+
+	debugfs_create_file("locking_state", S_IFREG|S_IRUSR,
+			    osb->osb_debug_root, osb, &ocfs2_dlm_debug_fops);
+
+	debugfs_create_u32("locking_filter", 0600, osb->osb_debug_root,
+			   &dlm_debug->d_filter_secs);
+	ocfs2_get_dlm_debug(dlm_debug);
+}
+
+static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)
+{
+	struct ocfs2_dlm_debug *dlm_debug = osb->osb_dlm_debug;
+
+	if (dlm_debug)
+		ocfs2_put_dlm_debug(dlm_debug);
+}
+
+int ocfs2_dlm_init(struct ocfs2_super *osb)
+{
+	int status = 0;
+	struct ocfs2_cluster_connection *conn = NULL;
+
+	if (ocfs2_mount_local(osb)) {
+		osb->node_num = 0;
+		goto local;
+	}
+
+	ocfs2_dlm_init_debug(osb);
+
+	/* launch downconvert thread */
+	osb->dc_task = kthread_run(ocfs2_downconvert_thread, osb, "ocfs2dc-%s",
+			osb->uuid_str);
+	if (IS_ERR(osb->dc_task)) {
+		status = PTR_ERR(osb->dc_task);
+		osb->dc_task = NULL;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	/* for now, uuid == domain */
+	status = ocfs2_cluster_connect(osb->osb_cluster_stack,
+				       osb->osb_cluster_name,
+				       strlen(osb->osb_cluster_name),
+				       osb->uuid_str,
+				       strlen(osb->uuid_str),
+				       &lproto, ocfs2_do_node_down, osb,
+				       &conn);
+	if (status) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	status = ocfs2_cluster_this_node(conn, &osb->node_num);
+	if (status < 0) {
+		mlog_errno(status);
+		mlog(ML_ERROR,
+		     "could not find this host's node number\n");
+		ocfs2_cluster_disconnect(conn, 0);
+		goto bail;
+	}
+
+local:
+	ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
+	ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
+	ocfs2_nfs_sync_lock_init(osb);
+	ocfs2_orphan_scan_lock_res_init(&osb->osb_orphan_scan.os_lockres, osb);
+
+	osb->cconn = conn;
+bail:
+	if (status < 0) {
+		ocfs2_dlm_shutdown_debug(osb);
+		if (osb->dc_task)
+			kthread_stop(osb->dc_task);
+	}
+
+	return status;
+}
+
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
+			int hangup_pending)
+{
+	ocfs2_drop_osb_locks(osb);
+
+	/*
+	 * Now that we have dropped all locks and ocfs2_dismount_volume()
+	 * has disabled recovery, the DLM won't be talking to us.  It's
+	 * safe to tear things down before disconnecting the cluster.
+	 */
+
+	if (osb->dc_task) {
+		kthread_stop(osb->dc_task);
+		osb->dc_task = NULL;
+	}
+
+	ocfs2_lock_res_free(&osb->osb_super_lockres);
+	ocfs2_lock_res_free(&osb->osb_rename_lockres);
+	ocfs2_lock_res_free(&osb->osb_nfs_sync_lockres);
+	ocfs2_lock_res_free(&osb->osb_orphan_scan.os_lockres);
+
+	if (osb->cconn) {
+		ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
+		osb->cconn = NULL;
+
+		ocfs2_dlm_shutdown_debug(osb);
+	}
+}
+
+static int ocfs2_drop_lock(struct ocfs2_super *osb,
+			   struct ocfs2_lock_res *lockres)
+{
+	int ret;
+	unsigned long flags;
+	u32 lkm_flags = 0;
+
+	/* We didn't get anywhere near actually using this lockres. */
+	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
+		goto out;
+
+	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
+		lkm_flags |= DLM_LKF_VALBLK;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+
+	mlog_bug_on_msg(!(lockres->l_flags & OCFS2_LOCK_FREEING),
+			"lockres %s, flags 0x%lx\n",
+			lockres->l_name, lockres->l_flags);
+
+	while (lockres->l_flags & OCFS2_LOCK_BUSY) {
+		mlog(0, "waiting on busy lock \"%s\": flags = %lx, action = "
+		     "%u, unlock_action = %u\n",
+		     lockres->l_name, lockres->l_flags, lockres->l_action,
+		     lockres->l_unlock_action);
+
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		/* XXX: Today we just wait on any busy
+		 * locks... Perhaps we need to cancel converts in the
+		 * future? */
+		ocfs2_wait_on_busy_lock(lockres);
+
+		spin_lock_irqsave(&lockres->l_lock, flags);
+	}
+
+	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
+		if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
+		    lockres->l_level == DLM_LOCK_EX &&
+		    !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
+			lockres->l_ops->set_lvb(lockres);
+	}
+
+	if (lockres->l_flags & OCFS2_LOCK_BUSY)
+		mlog(ML_ERROR, "destroying busy lock: \"%s\"\n",
+		     lockres->l_name);
+	if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
+		mlog(0, "destroying blocked lock: \"%s\"\n", lockres->l_name);
+
+	if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		goto out;
+	}
+
+	lockres_clear_flags(lockres, OCFS2_LOCK_ATTACHED);
+
+	/* make sure we never get here while waiting for an ast to
+	 * fire. */
+	BUG_ON(lockres->l_action != OCFS2_AST_INVALID);
+
+	/* is this necessary? */
+	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+	lockres->l_unlock_action = OCFS2_UNLOCK_DROP_LOCK;
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	mlog(0, "lock %s\n", lockres->l_name);
+
+	ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb, lkm_flags);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
+		mlog(ML_ERROR, "lockres flags: %lu\n", lockres->l_flags);
+		ocfs2_dlm_dump_lksb(&lockres->l_lksb);
+		BUG();
+	}
+	mlog(0, "lock %s, successful return from ocfs2_dlm_unlock\n",
+	     lockres->l_name);
+
+	ocfs2_wait_on_busy_lock(lockres);
+out:
+	return 0;
+}
+
+static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
+				       struct ocfs2_lock_res *lockres);
+
+/* Mark the lockres as being dropped. It will no longer be
+ * queued if blocking, but we still may have to wait on it
+ * being dequeued from the downconvert thread before we can consider
+ * it safe to drop.
+ *
+ * You can *not* attempt to call cluster_lock on this lockres anymore. */
+void ocfs2_mark_lockres_freeing(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres)
+{
+	int status;
+	struct ocfs2_mask_waiter mw;
+	unsigned long flags, flags2;
+
+	ocfs2_init_mask_waiter(&mw);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	lockres->l_flags |= OCFS2_LOCK_FREEING;
+	if (lockres->l_flags & OCFS2_LOCK_QUEUED && current == osb->dc_task) {
+		/*
+		 * We know the downconvert is queued but not in progress
+		 * because we are the downconvert thread and processing
+		 * different lock. So we can just remove the lock from the
+		 * queue. This is not only an optimization but also a way
+		 * to avoid the following deadlock:
+		 *   ocfs2_dentry_post_unlock()
+		 *     ocfs2_dentry_lock_put()
+		 *       ocfs2_drop_dentry_lock()
+		 *         iput()
+		 *           ocfs2_evict_inode()
+		 *             ocfs2_clear_inode()
+		 *               ocfs2_mark_lockres_freeing()
+		 *                 ... blocks waiting for OCFS2_LOCK_QUEUED
+		 *                 since we are the downconvert thread which
+		 *                 should clear the flag.
+		 */
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		spin_lock_irqsave(&osb->dc_task_lock, flags2);
+		list_del_init(&lockres->l_blocked_list);
+		osb->blocked_lock_count--;
+		spin_unlock_irqrestore(&osb->dc_task_lock, flags2);
+		/*
+		 * Warn if we recurse into another post_unlock call.  Strictly
+		 * speaking it isn't a problem but we need to be careful if
+		 * that happens (stack overflow, deadlocks, ...) so warn if
+		 * ocfs2 grows a path for which this can happen.
+		 */
+		WARN_ON_ONCE(lockres->l_ops->post_unlock);
+		/* Since the lock is freeing we don't do much in the fn below */
+		ocfs2_process_blocked_lock(osb, lockres);
+		return;
+	}
+	while (lockres->l_flags & OCFS2_LOCK_QUEUED) {
+		lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_QUEUED, 0);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+		mlog(0, "Waiting on lockres %s\n", lockres->l_name);
+
+		status = ocfs2_wait_for_mask(&mw);
+		if (status)
+			mlog_errno(status);
+
+		spin_lock_irqsave(&lockres->l_lock, flags);
+	}
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
+			       struct ocfs2_lock_res *lockres)
+{
+	int ret;
+
+	ocfs2_mark_lockres_freeing(osb, lockres);
+	ret = ocfs2_drop_lock(osb, lockres);
+	if (ret)
+		mlog_errno(ret);
+}
+
+static void ocfs2_drop_osb_locks(struct ocfs2_super *osb)
+{
+	ocfs2_simple_drop_lockres(osb, &osb->osb_super_lockres);
+	ocfs2_simple_drop_lockres(osb, &osb->osb_rename_lockres);
+	ocfs2_simple_drop_lockres(osb, &osb->osb_nfs_sync_lockres);
+	ocfs2_simple_drop_lockres(osb, &osb->osb_orphan_scan.os_lockres);
+}
+
+int ocfs2_drop_inode_locks(struct inode *inode)
+{
+	int status, err;
+
+	/* No need to call ocfs2_mark_lockres_freeing here -
+	 * ocfs2_clear_inode has done it for us. */
+
+	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
+			      &OCFS2_I(inode)->ip_open_lockres);
+	if (err < 0)
+		mlog_errno(err);
+
+	status = err;
+
+	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
+			      &OCFS2_I(inode)->ip_inode_lockres);
+	if (err < 0)
+		mlog_errno(err);
+	if (err < 0 && !status)
+		status = err;
+
+	err = ocfs2_drop_lock(OCFS2_SB(inode->i_sb),
+			      &OCFS2_I(inode)->ip_rw_lockres);
+	if (err < 0)
+		mlog_errno(err);
+	if (err < 0 && !status)
+		status = err;
+
+	return status;
+}
+
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+					      int new_level)
+{
+	assert_spin_locked(&lockres->l_lock);
+
+	BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
+
+	if (lockres->l_level <= new_level) {
+		mlog(ML_ERROR, "lockres %s, lvl %d <= %d, blcklst %d, mask %d, "
+		     "type %d, flags 0x%lx, hold %d %d, act %d %d, req %d, "
+		     "block %d, pgen %d\n", lockres->l_name, lockres->l_level,
+		     new_level, list_empty(&lockres->l_blocked_list),
+		     list_empty(&lockres->l_mask_waiters), lockres->l_type,
+		     lockres->l_flags, lockres->l_ro_holders,
+		     lockres->l_ex_holders, lockres->l_action,
+		     lockres->l_unlock_action, lockres->l_requested,
+		     lockres->l_blocking, lockres->l_pending_gen);
+		BUG();
+	}
+
+	mlog(ML_BASTS, "lockres %s, level %d => %d, blocking %d\n",
+	     lockres->l_name, lockres->l_level, new_level, lockres->l_blocking);
+
+	lockres->l_action = OCFS2_AST_DOWNCONVERT;
+	lockres->l_requested = new_level;
+	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+	return lockres_set_pending(lockres);
+}
+
+static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
+				  struct ocfs2_lock_res *lockres,
+				  int new_level,
+				  int lvb,
+				  unsigned int generation)
+{
+	int ret;
+	u32 dlm_flags = DLM_LKF_CONVERT;
+
+	mlog(ML_BASTS, "lockres %s, level %d => %d\n", lockres->l_name,
+	     lockres->l_level, new_level);
+
+	/*
+	 * On DLM_LKF_VALBLK, fsdlm behaves differently with o2cb. It always
+	 * expects DLM_LKF_VALBLK being set if the LKB has LVB, so that
+	 * we can recover correctly from node failure. Otherwise, we may get
+	 * invalid LVB in LKB, but without DLM_SBF_VALNOTVALID being set.
+	 */
+	if (ocfs2_userspace_stack(osb) &&
+	    lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
+		lvb = 1;
+
+	if (lvb)
+		dlm_flags |= DLM_LKF_VALBLK;
+
+	ret = ocfs2_dlm_lock(osb->cconn,
+			     new_level,
+			     &lockres->l_lksb,
+			     dlm_flags,
+			     lockres->l_name,
+			     OCFS2_LOCK_ID_MAX_LEN - 1);
+	lockres_clear_pending(lockres, generation, osb);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
+		ocfs2_recover_from_dlm_error(lockres, 1);
+		goto bail;
+	}
+
+	ret = 0;
+bail:
+	return ret;
+}
+
+/* returns 1 when the caller should unlock and call ocfs2_dlm_unlock */
+static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
+				        struct ocfs2_lock_res *lockres)
+{
+	assert_spin_locked(&lockres->l_lock);
+
+	if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT) {
+		/* If we're already trying to cancel a lock conversion
+		 * then just drop the spinlock and allow the caller to
+		 * requeue this lock. */
+		mlog(ML_BASTS, "lockres %s, skip convert\n", lockres->l_name);
+		return 0;
+	}
+
+	/* were we in a convert when we got the bast fire? */
+	BUG_ON(lockres->l_action != OCFS2_AST_CONVERT &&
+	       lockres->l_action != OCFS2_AST_DOWNCONVERT);
+	/* set things up for the unlockast to know to just
+	 * clear out the ast_action and unset busy, etc. */
+	lockres->l_unlock_action = OCFS2_UNLOCK_CANCEL_CONVERT;
+
+	mlog_bug_on_msg(!(lockres->l_flags & OCFS2_LOCK_BUSY),
+			"lock %s, invalid flags: 0x%lx\n",
+			lockres->l_name, lockres->l_flags);
+
+	mlog(ML_BASTS, "lockres %s\n", lockres->l_name);
+
+	return 1;
+}
+
+static int ocfs2_cancel_convert(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres)
+{
+	int ret;
+
+	ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb,
+			       DLM_LKF_CANCEL);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
+		ocfs2_recover_from_dlm_error(lockres, 0);
+	}
+
+	mlog(ML_BASTS, "lockres %s\n", lockres->l_name);
+
+	return ret;
+}
+
+static int ocfs2_unblock_lock(struct ocfs2_super *osb,
+			      struct ocfs2_lock_res *lockres,
+			      struct ocfs2_unblock_ctl *ctl)
+{
+	unsigned long flags;
+	int blocking;
+	int new_level;
+	int level;
+	int ret = 0;
+	int set_lvb = 0;
+	unsigned int gen;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+
+recheck:
+	/*
+	 * Is it still blocking? If not, we have no more work to do.
+	 */
+	if (!(lockres->l_flags & OCFS2_LOCK_BLOCKED)) {
+		BUG_ON(lockres->l_blocking != DLM_LOCK_NL);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		ret = 0;
+		goto leave;
+	}
+
+	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
+		/* XXX
+		 * This is a *big* race.  The OCFS2_LOCK_PENDING flag
+		 * exists entirely for one reason - another thread has set
+		 * OCFS2_LOCK_BUSY, but has *NOT* yet called dlm_lock().
+		 *
+		 * If we do ocfs2_cancel_convert() before the other thread
+		 * calls dlm_lock(), our cancel will do nothing.  We will
+		 * get no ast, and we will have no way of knowing the
+		 * cancel failed.  Meanwhile, the other thread will call
+		 * into dlm_lock() and wait...forever.
+		 *
+		 * Why forever?  Because another node has asked for the
+		 * lock first; that's why we're here in unblock_lock().
+		 *
+		 * The solution is OCFS2_LOCK_PENDING.  When PENDING is
+		 * set, we just requeue the unblock.  Only when the other
+		 * thread has called dlm_lock() and cleared PENDING will
+		 * we then cancel their request.
+		 *
+		 * All callers of dlm_lock() must set OCFS2_DLM_PENDING
+		 * at the same time they set OCFS2_DLM_BUSY.  They must
+		 * clear OCFS2_DLM_PENDING after dlm_lock() returns.
+		 */
+		if (lockres->l_flags & OCFS2_LOCK_PENDING) {
+			mlog(ML_BASTS, "lockres %s, ReQ: Pending\n",
+			     lockres->l_name);
+			goto leave_requeue;
+		}
+
+		ctl->requeue = 1;
+		ret = ocfs2_prepare_cancel_convert(osb, lockres);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		if (ret) {
+			ret = ocfs2_cancel_convert(osb, lockres);
+			if (ret < 0)
+				mlog_errno(ret);
+		}
+		goto leave;
+	}
+
+	/*
+	 * This prevents livelocks. OCFS2_LOCK_UPCONVERT_FINISHING flag is
+	 * set when the ast is received for an upconvert just before the
+	 * OCFS2_LOCK_BUSY flag is cleared. Now if the fs received a bast
+	 * on the heels of the ast, we want to delay the downconvert just
+	 * enough to allow the up requestor to do its task. Because this
+	 * lock is in the blocked queue, the lock will be downconverted
+	 * as soon as the requestor is done with the lock.
+	 */
+	if (lockres->l_flags & OCFS2_LOCK_UPCONVERT_FINISHING)
+		goto leave_requeue;
+
+	/*
+	 * How can we block and yet be at NL?  We were trying to upconvert
+	 * from NL and got canceled.  The code comes back here, and now
+	 * we notice and clear BLOCKING.
+	 */
+	if (lockres->l_level == DLM_LOCK_NL) {
+		BUG_ON(lockres->l_ex_holders || lockres->l_ro_holders);
+		mlog(ML_BASTS, "lockres %s, Aborting dc\n", lockres->l_name);
+		lockres->l_blocking = DLM_LOCK_NL;
+		lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
+		spin_unlock_irqrestore(&lockres->l_lock, flags);
+		goto leave;
+	}
+
+	/* if we're blocking an exclusive and we have *any* holders,
+	 * then requeue. */
+	if ((lockres->l_blocking == DLM_LOCK_EX)
+	    && (lockres->l_ex_holders || lockres->l_ro_holders)) {
+		mlog(ML_BASTS, "lockres %s, ReQ: EX/PR Holders %u,%u\n",
+		     lockres->l_name, lockres->l_ex_holders,
+		     lockres->l_ro_holders);
+		goto leave_requeue;
+	}
+
+	/* If it's a PR we're blocking, then only
+	 * requeue if we've got any EX holders */
+	if (lockres->l_blocking == DLM_LOCK_PR &&
+	    lockres->l_ex_holders) {
+		mlog(ML_BASTS, "lockres %s, ReQ: EX Holders %u\n",
+		     lockres->l_name, lockres->l_ex_holders);
+		goto leave_requeue;
+	}
+
+	/*
+	 * Can we get a lock in this state if the holder counts are
+	 * zero? The meta data unblock code used to check this.
+	 */
+	if ((lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
+	    && (lockres->l_flags & OCFS2_LOCK_REFRESHING)) {
+		mlog(ML_BASTS, "lockres %s, ReQ: Lock Refreshing\n",
+		     lockres->l_name);
+		goto leave_requeue;
+	}
+
+	new_level = ocfs2_highest_compat_lock_level(lockres->l_blocking);
+
+	if (lockres->l_ops->check_downconvert
+	    && !lockres->l_ops->check_downconvert(lockres, new_level)) {
+		mlog(ML_BASTS, "lockres %s, ReQ: Checkpointing\n",
+		     lockres->l_name);
+		goto leave_requeue;
+	}
+
+	/* If we get here, then we know that there are no more
+	 * incompatible holders (and anyone asking for an incompatible
+	 * lock is blocked). We can now downconvert the lock */
+	if (!lockres->l_ops->downconvert_worker)
+		goto downconvert;
+
+	/* Some lockres types want to do a bit of work before
+	 * downconverting a lock. Allow that here. The worker function
+	 * may sleep, so we save off a copy of what we're blocking as
+	 * it may change while we're not holding the spin lock. */
+	blocking = lockres->l_blocking;
+	level = lockres->l_level;
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	ctl->unblock_action = lockres->l_ops->downconvert_worker(lockres, blocking);
+
+	if (ctl->unblock_action == UNBLOCK_STOP_POST) {
+		mlog(ML_BASTS, "lockres %s, UNBLOCK_STOP_POST\n",
+		     lockres->l_name);
+		goto leave;
+	}
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if ((blocking != lockres->l_blocking) || (level != lockres->l_level)) {
+		/* If this changed underneath us, then we can't drop
+		 * it just yet. */
+		mlog(ML_BASTS, "lockres %s, block=%d:%d, level=%d:%d, "
+		     "Recheck\n", lockres->l_name, blocking,
+		     lockres->l_blocking, level, lockres->l_level);
+		goto recheck;
+	}
+
+downconvert:
+	ctl->requeue = 0;
+
+	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
+		if (lockres->l_level == DLM_LOCK_EX)
+			set_lvb = 1;
+
+		/*
+		 * We only set the lvb if the lock has been fully
+		 * refreshed - otherwise we risk setting stale
+		 * data. Otherwise, there's no need to actually clear
+		 * out the lvb here as it's value is still valid.
+		 */
+		if (set_lvb && !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
+			lockres->l_ops->set_lvb(lockres);
+	}
+
+	gen = ocfs2_prepare_downconvert(lockres, new_level);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+	ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb,
+				     gen);
+	/* The dlm lock convert is being cancelled in background,
+	 * ocfs2_cancel_convert() is asynchronous in fs/dlm,
+	 * requeue it, try again later.
+	 */
+	if (ret == -EBUSY) {
+		ctl->requeue = 1;
+		mlog(ML_BASTS, "lockres %s, ReQ: Downconvert busy\n",
+		     lockres->l_name);
+		ret = 0;
+		msleep(20);
+	}
+
+leave:
+	if (ret)
+		mlog_errno(ret);
+	return ret;
+
+leave_requeue:
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+	ctl->requeue = 1;
+
+	return 0;
+}
+
+static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
+				     int blocking)
+{
+	struct inode *inode;
+	struct address_space *mapping;
+	struct ocfs2_inode_info *oi;
+
+       	inode = ocfs2_lock_res_inode(lockres);
+	mapping = inode->i_mapping;
+
+	if (S_ISDIR(inode->i_mode)) {
+		oi = OCFS2_I(inode);
+		oi->ip_dir_lock_gen++;
+		mlog(0, "generation: %u\n", oi->ip_dir_lock_gen);
+		goto out_forget;
+	}
+
+	if (!S_ISREG(inode->i_mode))
+		goto out;
+
+	/*
+	 * We need this before the filemap_fdatawrite() so that it can
+	 * transfer the dirty bit from the PTE to the
+	 * page. Unfortunately this means that even for EX->PR
+	 * downconverts, we'll lose our mappings and have to build
+	 * them up again.
+	 */
+	unmap_mapping_range(mapping, 0, 0, 0);
+
+	if (filemap_fdatawrite(mapping)) {
+		mlog(ML_ERROR, "Could not sync inode %llu for downconvert!",
+		     (unsigned long long)OCFS2_I(inode)->ip_blkno);
+	}
+	sync_mapping_buffers(mapping);
+	if (blocking == DLM_LOCK_EX) {
+		truncate_inode_pages(mapping, 0);
+	} else {
+		/* We only need to wait on the I/O if we're not also
+		 * truncating pages because truncate_inode_pages waits
+		 * for us above. We don't truncate pages if we're
+		 * blocking anything < EXMODE because we want to keep
+		 * them around in that case. */
+		filemap_fdatawait(mapping);
+	}
+
+out_forget:
+	forget_all_cached_acls(inode);
+
+out:
+	return UNBLOCK_CONTINUE;
+}
+
+static int ocfs2_ci_checkpointed(struct ocfs2_caching_info *ci,
+				 struct ocfs2_lock_res *lockres,
+				 int new_level)
+{
+	int checkpointed = ocfs2_ci_fully_checkpointed(ci);
+
+	BUG_ON(new_level != DLM_LOCK_NL && new_level != DLM_LOCK_PR);
+	BUG_ON(lockres->l_level != DLM_LOCK_EX && !checkpointed);
+
+	if (checkpointed)
+		return 1;
+
+	ocfs2_start_checkpoint(OCFS2_SB(ocfs2_metadata_cache_get_super(ci)));
+	return 0;
+}
+
+static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
+					int new_level)
+{
+	struct inode *inode = ocfs2_lock_res_inode(lockres);
+
+	return ocfs2_ci_checkpointed(INODE_CACHE(inode), lockres, new_level);
+}
+
+static void ocfs2_set_meta_lvb(struct ocfs2_lock_res *lockres)
+{
+	struct inode *inode = ocfs2_lock_res_inode(lockres);
+
+	__ocfs2_stuff_meta_lvb(inode);
+}
+
+/*
+ * Does the final reference drop on our dentry lock. Right now this
+ * happens in the downconvert thread, but we could choose to simplify the
+ * dlmglue API and push these off to the ocfs2_wq in the future.
+ */
+static void ocfs2_dentry_post_unlock(struct ocfs2_super *osb,
+				     struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_dentry_lock *dl = ocfs2_lock_res_dl(lockres);
+	ocfs2_dentry_lock_put(osb, dl);
+}
+
+/*
+ * d_delete() matching dentries before the lock downconvert.
+ *
+ * At this point, any process waiting to destroy the
+ * dentry_lock due to last ref count is stopped by the
+ * OCFS2_LOCK_QUEUED flag.
+ *
+ * We have two potential problems
+ *
+ * 1) If we do the last reference drop on our dentry_lock (via dput)
+ *    we'll wind up in ocfs2_release_dentry_lock(), waiting on
+ *    the downconvert to finish. Instead we take an elevated
+ *    reference and push the drop until after we've completed our
+ *    unblock processing.
+ *
+ * 2) There might be another process with a final reference,
+ *    waiting on us to finish processing. If this is the case, we
+ *    detect it and exit out - there's no more dentries anyway.
+ */
+static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
+				       int blocking)
+{
+	struct ocfs2_dentry_lock *dl = ocfs2_lock_res_dl(lockres);
+	struct ocfs2_inode_info *oi = OCFS2_I(dl->dl_inode);
+	struct dentry *dentry;
+	unsigned long flags;
+	int extra_ref = 0;
+
+	/*
+	 * This node is blocking another node from getting a read
+	 * lock. This happens when we've renamed within a
+	 * directory. We've forced the other nodes to d_delete(), but
+	 * we never actually dropped our lock because it's still
+	 * valid. The downconvert code will retain a PR for this node,
+	 * so there's no further work to do.
+	 */
+	if (blocking == DLM_LOCK_PR)
+		return UNBLOCK_CONTINUE;
+
+	/*
+	 * Mark this inode as potentially orphaned. The code in
+	 * ocfs2_delete_inode() will figure out whether it actually
+	 * needs to be freed or not.
+	 */
+	spin_lock(&oi->ip_lock);
+	oi->ip_flags |= OCFS2_INODE_MAYBE_ORPHANED;
+	spin_unlock(&oi->ip_lock);
+
+	/*
+	 * Yuck. We need to make sure however that the check of
+	 * OCFS2_LOCK_FREEING and the extra reference are atomic with
+	 * respect to a reference decrement or the setting of that
+	 * flag.
+	 */
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	spin_lock(&dentry_attach_lock);
+	if (!(lockres->l_flags & OCFS2_LOCK_FREEING)
+	    && dl->dl_count) {
+		dl->dl_count++;
+		extra_ref = 1;
+	}
+	spin_unlock(&dentry_attach_lock);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	mlog(0, "extra_ref = %d\n", extra_ref);
+
+	/*
+	 * We have a process waiting on us in ocfs2_dentry_iput(),
+	 * which means we can't have any more outstanding
+	 * aliases. There's no need to do any more work.
+	 */
+	if (!extra_ref)
+		return UNBLOCK_CONTINUE;
+
+	spin_lock(&dentry_attach_lock);
+	while (1) {
+		dentry = ocfs2_find_local_alias(dl->dl_inode,
+						dl->dl_parent_blkno, 1);
+		if (!dentry)
+			break;
+		spin_unlock(&dentry_attach_lock);
+
+		if (S_ISDIR(dl->dl_inode->i_mode))
+			shrink_dcache_parent(dentry);
+
+		mlog(0, "d_delete(%pd);\n", dentry);
+
+		/*
+		 * The following dcache calls may do an
+		 * iput(). Normally we don't want that from the
+		 * downconverting thread, but in this case it's ok
+		 * because the requesting node already has an
+		 * exclusive lock on the inode, so it can't be queued
+		 * for a downconvert.
+		 */
+		d_delete(dentry);
+		dput(dentry);
+
+		spin_lock(&dentry_attach_lock);
+	}
+	spin_unlock(&dentry_attach_lock);
+
+	/*
+	 * If we are the last holder of this dentry lock, there is no
+	 * reason to downconvert so skip straight to the unlock.
+	 */
+	if (dl->dl_count == 1)
+		return UNBLOCK_STOP_POST;
+
+	return UNBLOCK_CONTINUE_POST;
+}
+
+static int ocfs2_check_refcount_downconvert(struct ocfs2_lock_res *lockres,
+					    int new_level)
+{
+	struct ocfs2_refcount_tree *tree =
+				ocfs2_lock_res_refcount_tree(lockres);
+
+	return ocfs2_ci_checkpointed(&tree->rf_ci, lockres, new_level);
+}
+
+static int ocfs2_refcount_convert_worker(struct ocfs2_lock_res *lockres,
+					 int blocking)
+{
+	struct ocfs2_refcount_tree *tree =
+				ocfs2_lock_res_refcount_tree(lockres);
+
+	ocfs2_metadata_cache_purge(&tree->rf_ci);
+
+	return UNBLOCK_CONTINUE;
+}
+
+static void ocfs2_set_qinfo_lvb(struct ocfs2_lock_res *lockres)
+{
+	struct ocfs2_qinfo_lvb *lvb;
+	struct ocfs2_mem_dqinfo *oinfo = ocfs2_lock_res_qinfo(lockres);
+	struct mem_dqinfo *info = sb_dqinfo(oinfo->dqi_gi.dqi_sb,
+					    oinfo->dqi_gi.dqi_type);
+
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	lvb->lvb_version = OCFS2_QINFO_LVB_VERSION;
+	lvb->lvb_bgrace = cpu_to_be32(info->dqi_bgrace);
+	lvb->lvb_igrace = cpu_to_be32(info->dqi_igrace);
+	lvb->lvb_syncms = cpu_to_be32(oinfo->dqi_syncms);
+	lvb->lvb_blocks = cpu_to_be32(oinfo->dqi_gi.dqi_blocks);
+	lvb->lvb_free_blk = cpu_to_be32(oinfo->dqi_gi.dqi_free_blk);
+	lvb->lvb_free_entry = cpu_to_be32(oinfo->dqi_gi.dqi_free_entry);
+}
+
+void ocfs2_qinfo_unlock(struct ocfs2_mem_dqinfo *oinfo, int ex)
+{
+	struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
+	struct ocfs2_super *osb = OCFS2_SB(oinfo->dqi_gi.dqi_sb);
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+
+	if (!ocfs2_is_hard_readonly(osb) && !ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, level);
+}
+
+static int ocfs2_refresh_qinfo(struct ocfs2_mem_dqinfo *oinfo)
+{
+	struct mem_dqinfo *info = sb_dqinfo(oinfo->dqi_gi.dqi_sb,
+					    oinfo->dqi_gi.dqi_type);
+	struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
+	struct ocfs2_qinfo_lvb *lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	struct buffer_head *bh = NULL;
+	struct ocfs2_global_disk_dqinfo *gdinfo;
+	int status = 0;
+
+	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb) &&
+	    lvb->lvb_version == OCFS2_QINFO_LVB_VERSION) {
+		info->dqi_bgrace = be32_to_cpu(lvb->lvb_bgrace);
+		info->dqi_igrace = be32_to_cpu(lvb->lvb_igrace);
+		oinfo->dqi_syncms = be32_to_cpu(lvb->lvb_syncms);
+		oinfo->dqi_gi.dqi_blocks = be32_to_cpu(lvb->lvb_blocks);
+		oinfo->dqi_gi.dqi_free_blk = be32_to_cpu(lvb->lvb_free_blk);
+		oinfo->dqi_gi.dqi_free_entry =
+					be32_to_cpu(lvb->lvb_free_entry);
+	} else {
+		status = ocfs2_read_quota_phys_block(oinfo->dqi_gqinode,
+						     oinfo->dqi_giblk, &bh);
+		if (status) {
+			mlog_errno(status);
+			goto bail;
+		}
+		gdinfo = (struct ocfs2_global_disk_dqinfo *)
+					(bh->b_data + OCFS2_GLOBAL_INFO_OFF);
+		info->dqi_bgrace = le32_to_cpu(gdinfo->dqi_bgrace);
+		info->dqi_igrace = le32_to_cpu(gdinfo->dqi_igrace);
+		oinfo->dqi_syncms = le32_to_cpu(gdinfo->dqi_syncms);
+		oinfo->dqi_gi.dqi_blocks = le32_to_cpu(gdinfo->dqi_blocks);
+		oinfo->dqi_gi.dqi_free_blk = le32_to_cpu(gdinfo->dqi_free_blk);
+		oinfo->dqi_gi.dqi_free_entry =
+					le32_to_cpu(gdinfo->dqi_free_entry);
+		brelse(bh);
+		ocfs2_track_lock_refresh(lockres);
+	}
+
+bail:
+	return status;
+}
+
+/* Lock quota info, this function expects at least shared lock on the quota file
+ * so that we can safely refresh quota info from disk. */
+int ocfs2_qinfo_lock(struct ocfs2_mem_dqinfo *oinfo, int ex)
+{
+	struct ocfs2_lock_res *lockres = &oinfo->dqi_gqlock;
+	struct ocfs2_super *osb = OCFS2_SB(oinfo->dqi_gi.dqi_sb);
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	int status = 0;
+
+	/* On RO devices, locking really isn't needed... */
+	if (ocfs2_is_hard_readonly(osb)) {
+		if (ex)
+			status = -EROFS;
+		goto bail;
+	}
+	if (ocfs2_mount_local(osb))
+		goto bail;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+	if (!ocfs2_should_refresh_lock_res(lockres))
+		goto bail;
+	/* OK, we have the lock but we need to refresh the quota info */
+	status = ocfs2_refresh_qinfo(oinfo);
+	if (status)
+		ocfs2_qinfo_unlock(oinfo, ex);
+	ocfs2_complete_lock_res_refresh(lockres, status);
+bail:
+	return status;
+}
+
+int ocfs2_refcount_lock(struct ocfs2_refcount_tree *ref_tree, int ex)
+{
+	int status;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &ref_tree->rf_lockres;
+	struct ocfs2_super *osb = lockres->l_priv;
+
+
+	if (ocfs2_is_hard_readonly(osb))
+		return -EROFS;
+
+	if (ocfs2_mount_local(osb))
+		return 0;
+
+	status = ocfs2_cluster_lock(osb, lockres, level, 0, 0);
+	if (status < 0)
+		mlog_errno(status);
+
+	return status;
+}
+
+void ocfs2_refcount_unlock(struct ocfs2_refcount_tree *ref_tree, int ex)
+{
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
+	struct ocfs2_lock_res *lockres = &ref_tree->rf_lockres;
+	struct ocfs2_super *osb = lockres->l_priv;
+
+	if (!ocfs2_mount_local(osb))
+		ocfs2_cluster_unlock(osb, lockres, level);
+}
+
+static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
+				       struct ocfs2_lock_res *lockres)
+{
+	int status;
+	struct ocfs2_unblock_ctl ctl = {0, 0,};
+	unsigned long flags;
+
+	/* Our reference to the lockres in this function can be
+	 * considered valid until we remove the OCFS2_LOCK_QUEUED
+	 * flag. */
+
+	BUG_ON(!lockres);
+	BUG_ON(!lockres->l_ops);
+
+	mlog(ML_BASTS, "lockres %s blocked\n", lockres->l_name);
+
+	/* Detect whether a lock has been marked as going away while
+	 * the downconvert thread was processing other things. A lock can
+	 * still be marked with OCFS2_LOCK_FREEING after this check,
+	 * but short circuiting here will still save us some
+	 * performance. */
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	if (lockres->l_flags & OCFS2_LOCK_FREEING)
+		goto unqueue;
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	status = ocfs2_unblock_lock(osb, lockres, &ctl);
+	if (status < 0)
+		mlog_errno(status);
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+unqueue:
+	if (lockres->l_flags & OCFS2_LOCK_FREEING || !ctl.requeue) {
+		lockres_clear_flags(lockres, OCFS2_LOCK_QUEUED);
+	} else
+		ocfs2_schedule_blocked_lock(osb, lockres);
+
+	mlog(ML_BASTS, "lockres %s, requeue = %s.\n", lockres->l_name,
+	     ctl.requeue ? "yes" : "no");
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+
+	if (ctl.unblock_action != UNBLOCK_CONTINUE
+	    && lockres->l_ops->post_unlock)
+		lockres->l_ops->post_unlock(osb, lockres);
+}
+
+static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
+					struct ocfs2_lock_res *lockres)
+{
+	unsigned long flags;
+
+	assert_spin_locked(&lockres->l_lock);
+
+	if (lockres->l_flags & OCFS2_LOCK_FREEING) {
+		/* Do not schedule a lock for downconvert when it's on
+		 * the way to destruction - any nodes wanting access
+		 * to the resource will get it soon. */
+		mlog(ML_BASTS, "lockres %s won't be scheduled: flags 0x%lx\n",
+		     lockres->l_name, lockres->l_flags);
+		return;
+	}
+
+	lockres_or_flags(lockres, OCFS2_LOCK_QUEUED);
+
+	spin_lock_irqsave(&osb->dc_task_lock, flags);
+	if (list_empty(&lockres->l_blocked_list)) {
+		list_add_tail(&lockres->l_blocked_list,
+			      &osb->blocked_lock_list);
+		osb->blocked_lock_count++;
+	}
+	spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+}
+
+static void ocfs2_downconvert_thread_do_work(struct ocfs2_super *osb)
+{
+	unsigned long processed;
+	unsigned long flags;
+	struct ocfs2_lock_res *lockres;
+
+	spin_lock_irqsave(&osb->dc_task_lock, flags);
+	/* grab this early so we know to try again if a state change and
+	 * wake happens part-way through our work  */
+	osb->dc_work_sequence = osb->dc_wake_sequence;
+
+	processed = osb->blocked_lock_count;
+	/*
+	 * blocked lock processing in this loop might call iput which can
+	 * remove items off osb->blocked_lock_list. Downconvert up to
+	 * 'processed' number of locks, but stop short if we had some
+	 * removed in ocfs2_mark_lockres_freeing when downconverting.
+	 */
+	while (processed && !list_empty(&osb->blocked_lock_list)) {
+		lockres = list_entry(osb->blocked_lock_list.next,
+				     struct ocfs2_lock_res, l_blocked_list);
+		list_del_init(&lockres->l_blocked_list);
+		osb->blocked_lock_count--;
+		spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+
+		BUG_ON(!processed);
+		processed--;
+
+		ocfs2_process_blocked_lock(osb, lockres);
+
+		spin_lock_irqsave(&osb->dc_task_lock, flags);
+	}
+	spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+}
+
+static int ocfs2_downconvert_thread_lists_empty(struct ocfs2_super *osb)
+{
+	int empty = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&osb->dc_task_lock, flags);
+	if (list_empty(&osb->blocked_lock_list))
+		empty = 1;
+
+	spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+	return empty;
+}
+
+static int ocfs2_downconvert_thread_should_wake(struct ocfs2_super *osb)
+{
+	int should_wake = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&osb->dc_task_lock, flags);
+	if (osb->dc_work_sequence != osb->dc_wake_sequence)
+		should_wake = 1;
+	spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+
+	return should_wake;
+}
+
+static int ocfs2_downconvert_thread(void *arg)
+{
+	struct ocfs2_super *osb = arg;
+
+	/* only quit once we've been asked to stop and there is no more
+	 * work available */
+	while (!(kthread_should_stop() &&
+		ocfs2_downconvert_thread_lists_empty(osb))) {
+
+		wait_event_interruptible(osb->dc_event,
+					 ocfs2_downconvert_thread_should_wake(osb) ||
+					 kthread_should_stop());
+
+		mlog(0, "downconvert_thread: awoken\n");
+
+		ocfs2_downconvert_thread_do_work(osb);
+	}
+
+	osb->dc_task = NULL;
+	return 0;
+}
+
+void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&osb->dc_task_lock, flags);
+	/* make sure the voting thread gets a swipe at whatever changes
+	 * the caller may have made to the voting state */
+	osb->dc_wake_sequence++;
+	spin_unlock_irqrestore(&osb->dc_task_lock, flags);
+	wake_up(&osb->dc_event);
+}
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
new file mode 100644
index 000000000..e5da5809e
--- /dev/null
+++ b/fs/ocfs2/dlmglue.h
@@ -0,0 +1,209 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * dlmglue.h
+ *
+ * description here
+ *
+ * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
+ */
+
+
+#ifndef DLMGLUE_H
+#define DLMGLUE_H
+
+#include "dcache.h"
+
+#define OCFS2_LVB_VERSION 5
+
+struct ocfs2_meta_lvb {
+	__u8         lvb_version;
+	__u8         lvb_reserved0;
+	__be16       lvb_idynfeatures;
+	__be32       lvb_iclusters;
+	__be32       lvb_iuid;
+	__be32       lvb_igid;
+	__be64       lvb_iatime_packed;
+	__be64       lvb_ictime_packed;
+	__be64       lvb_imtime_packed;
+	__be64       lvb_isize;
+	__be16       lvb_imode;
+	__be16       lvb_inlink;
+	__be32       lvb_iattr;
+	__be32       lvb_igeneration;
+	__be32       lvb_reserved2;
+};
+
+#define OCFS2_QINFO_LVB_VERSION 1
+
+struct ocfs2_qinfo_lvb {
+	__u8	lvb_version;
+	__u8	lvb_reserved[3];
+	__be32	lvb_bgrace;
+	__be32	lvb_igrace;
+	__be32	lvb_syncms;
+	__be32	lvb_blocks;
+	__be32	lvb_free_blk;
+	__be32	lvb_free_entry;
+};
+
+#define OCFS2_ORPHAN_LVB_VERSION 1
+
+struct ocfs2_orphan_scan_lvb {
+	__u8	lvb_version;
+	__u8	lvb_reserved[3];
+	__be32	lvb_os_seqno;
+};
+
+#define OCFS2_TRIMFS_LVB_VERSION 1
+
+struct ocfs2_trim_fs_lvb {
+	__u8	lvb_version;
+	__u8	lvb_success;
+	__u8	lvb_reserved[2];
+	__be32	lvb_nodenum;
+	__be64	lvb_start;
+	__be64	lvb_len;
+	__be64	lvb_minlen;
+	__be64	lvb_trimlen;
+};
+
+struct ocfs2_trim_fs_info {
+	u8	tf_valid;	/* lvb is valid, or not */
+	u8	tf_success;	/* trim is successful, or not */
+	u32	tf_nodenum;	/* osb node number */
+	u64	tf_start;	/* trim start offset in clusters */
+	u64	tf_len;		/* trim end offset in clusters */
+	u64	tf_minlen;	/* trim minimum contiguous free clusters */
+	u64	tf_trimlen;	/* trimmed length in bytes */
+};
+
+struct ocfs2_lock_holder {
+	struct list_head oh_list;
+	struct pid *oh_owner_pid;
+	int oh_ex;
+};
+
+/* ocfs2_inode_lock_full() 'arg_flags' flags */
+/* don't wait on recovery. */
+#define OCFS2_META_LOCK_RECOVERY	(0x01)
+/* Instruct the dlm not to queue ourselves on the other node. */
+#define OCFS2_META_LOCK_NOQUEUE		(0x02)
+/* don't block waiting for the downconvert thread, instead return -EAGAIN */
+#define OCFS2_LOCK_NONBLOCK		(0x04)
+/* just get back disk inode bh if we've got cluster lock. */
+#define OCFS2_META_LOCK_GETBH		(0x08)
+
+/* Locking subclasses of inode cluster lock */
+enum {
+	OI_LS_NORMAL = 0,
+	OI_LS_PARENT,
+	OI_LS_RENAME1,
+	OI_LS_RENAME2,
+	OI_LS_REFLINK_TARGET,
+};
+
+int ocfs2_dlm_init(struct ocfs2_super *osb);
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb, int hangup_pending);
+void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res);
+void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
+			       enum ocfs2_lock_type type,
+			       unsigned int generation,
+			       struct inode *inode);
+void ocfs2_dentry_lock_res_init(struct ocfs2_dentry_lock *dl,
+				u64 parent, struct inode *inode);
+struct ocfs2_file_private;
+void ocfs2_file_lock_res_init(struct ocfs2_lock_res *lockres,
+			      struct ocfs2_file_private *fp);
+struct ocfs2_mem_dqinfo;
+void ocfs2_qinfo_lock_res_init(struct ocfs2_lock_res *lockres,
+                               struct ocfs2_mem_dqinfo *info);
+void ocfs2_refcount_lock_res_init(struct ocfs2_lock_res *lockres,
+				  struct ocfs2_super *osb, u64 ref_blkno,
+				  unsigned int generation);
+void ocfs2_lock_res_free(struct ocfs2_lock_res *res);
+int ocfs2_create_new_inode_locks(struct inode *inode);
+int ocfs2_drop_inode_locks(struct inode *inode);
+int ocfs2_rw_lock(struct inode *inode, int write);
+int ocfs2_try_rw_lock(struct inode *inode, int write);
+void ocfs2_rw_unlock(struct inode *inode, int write);
+int ocfs2_open_lock(struct inode *inode);
+int ocfs2_try_open_lock(struct inode *inode, int write);
+void ocfs2_open_unlock(struct inode *inode);
+int ocfs2_inode_lock_atime(struct inode *inode,
+			  struct vfsmount *vfsmnt,
+			  int *level, int wait);
+int ocfs2_inode_lock_full_nested(struct inode *inode,
+			 struct buffer_head **ret_bh,
+			 int ex,
+			 int arg_flags,
+			 int subclass);
+int ocfs2_inode_lock_with_page(struct inode *inode,
+			      struct buffer_head **ret_bh,
+			      int ex,
+			      struct page *page);
+/* Variants without special locking class or flags */
+#define ocfs2_inode_lock_full(i, r, e, f)\
+		ocfs2_inode_lock_full_nested(i, r, e, f, OI_LS_NORMAL)
+#define ocfs2_inode_lock_nested(i, b, e, s)\
+		ocfs2_inode_lock_full_nested(i, b, e, 0, s)
+/* 99% of the time we don't want to supply any additional flags --
+ * those are for very specific cases only. */
+#define ocfs2_inode_lock(i, b, e) ocfs2_inode_lock_full_nested(i, b, e, 0, OI_LS_NORMAL)
+#define ocfs2_try_inode_lock(i, b, e)\
+		ocfs2_inode_lock_full_nested(i, b, e, OCFS2_META_LOCK_NOQUEUE,\
+		OI_LS_NORMAL)
+void ocfs2_inode_unlock(struct inode *inode,
+		       int ex);
+int ocfs2_super_lock(struct ocfs2_super *osb,
+		     int ex);
+void ocfs2_super_unlock(struct ocfs2_super *osb,
+			int ex);
+int ocfs2_orphan_scan_lock(struct ocfs2_super *osb, u32 *seqno);
+void ocfs2_orphan_scan_unlock(struct ocfs2_super *osb, u32 seqno);
+
+int ocfs2_rename_lock(struct ocfs2_super *osb);
+void ocfs2_rename_unlock(struct ocfs2_super *osb);
+int ocfs2_nfs_sync_lock(struct ocfs2_super *osb, int ex);
+void ocfs2_nfs_sync_unlock(struct ocfs2_super *osb, int ex);
+void ocfs2_trim_fs_lock_res_init(struct ocfs2_super *osb);
+void ocfs2_trim_fs_lock_res_uninit(struct ocfs2_super *osb);
+int ocfs2_trim_fs_lock(struct ocfs2_super *osb,
+		       struct ocfs2_trim_fs_info *info, int trylock);
+void ocfs2_trim_fs_unlock(struct ocfs2_super *osb,
+			  struct ocfs2_trim_fs_info *info);
+int ocfs2_dentry_lock(struct dentry *dentry, int ex);
+void ocfs2_dentry_unlock(struct dentry *dentry, int ex);
+int ocfs2_file_lock(struct file *file, int ex, int trylock);
+void ocfs2_file_unlock(struct file *file);
+int ocfs2_qinfo_lock(struct ocfs2_mem_dqinfo *oinfo, int ex);
+void ocfs2_qinfo_unlock(struct ocfs2_mem_dqinfo *oinfo, int ex);
+struct ocfs2_refcount_tree;
+int ocfs2_refcount_lock(struct ocfs2_refcount_tree *ref_tree, int ex);
+void ocfs2_refcount_unlock(struct ocfs2_refcount_tree *ref_tree, int ex);
+
+
+void ocfs2_mark_lockres_freeing(struct ocfs2_super *osb,
+				struct ocfs2_lock_res *lockres);
+void ocfs2_simple_drop_lockres(struct ocfs2_super *osb,
+			       struct ocfs2_lock_res *lockres);
+
+/* for the downconvert thread */
+void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb);
+
+struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void);
+void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug);
+
+/* To set the locking protocol on module initialization */
+void ocfs2_set_locking_protocol(void);
+
+/* The _tracker pair is used to avoid cluster recursive locking */
+int ocfs2_inode_lock_tracker(struct inode *inode,
+			     struct buffer_head **ret_bh,
+			     int ex,
+			     struct ocfs2_lock_holder *oh);
+void ocfs2_inode_unlock_tracker(struct inode *inode,
+				int ex,
+				struct ocfs2_lock_holder *oh,
+				int had_lock);
+
+#endif	/* DLMGLUE_H */