Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 4470 insertions, 0 deletions

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);
+}