Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 682 insertions, 0 deletions

diff --git a/fs/ocfs2/dlmfs/userdlm.c b/fs/ocfs2/dlmfs/userdlm.c
new file mode 100644
index 0000000000..617c92e7b9
--- /dev/null
+++ b/fs/ocfs2/dlmfs/userdlm.c
@@ -0,0 +1,682 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * userdlm.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM.
+ *
+ * Many of the functions here are pared down versions of dlmglue.c
+ * functions.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched/signal.h>
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/crc32.h>
+
+#include "../ocfs2_lockingver.h"
+#include "../stackglue.h"
+#include "userdlm.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "../cluster/masklog.h"
+
+
+static inline struct user_lock_res *user_lksb_to_lock_res(struct ocfs2_dlm_lksb *lksb)
+{
+	return container_of(lksb, struct user_lock_res, l_lksb);
+}
+
+static inline int user_check_wait_flag(struct user_lock_res *lockres,
+				       int flag)
+{
+	int ret;
+
+	spin_lock(&lockres->l_lock);
+	ret = lockres->l_flags & flag;
+	spin_unlock(&lockres->l_lock);
+
+	return ret;
+}
+
+static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !user_check_wait_flag(lockres, USER_LOCK_BUSY));
+}
+
+static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
+
+{
+	wait_event(lockres->l_event,
+		   !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
+}
+
+/* I heart container_of... */
+static inline struct ocfs2_cluster_connection *
+cluster_connection_from_user_lockres(struct user_lock_res *lockres)
+{
+	struct dlmfs_inode_private *ip;
+
+	ip = container_of(lockres,
+			  struct dlmfs_inode_private,
+			  ip_lockres);
+	return ip->ip_conn;
+}
+
+static struct inode *
+user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
+{
+	struct dlmfs_inode_private *ip;
+
+	ip = container_of(lockres,
+			  struct dlmfs_inode_private,
+			  ip_lockres);
+	return &ip->ip_vfs_inode;
+}
+
+static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
+{
+	spin_lock(&lockres->l_lock);
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+	spin_unlock(&lockres->l_lock);
+}
+
+#define user_log_dlm_error(_func, _stat, _lockres) do {			\
+	mlog(ML_ERROR, "Dlm error %d while calling %s on "		\
+		"resource %.*s\n", _stat, _func,			\
+		_lockres->l_namelen, _lockres->l_name); 		\
+} while (0)
+
+/* WARNING: This function lives in a world where the only three lock
+ * levels are EX, PR, and NL. It *will* have to be adjusted when more
+ * lock types are added. */
+static inline int user_highest_compat_lock_level(int level)
+{
+	int new_level = DLM_LOCK_EX;
+
+	if (level == DLM_LOCK_EX)
+		new_level = DLM_LOCK_NL;
+	else if (level == DLM_LOCK_PR)
+		new_level = DLM_LOCK_PR;
+	return new_level;
+}
+
+static void user_ast(struct ocfs2_dlm_lksb *lksb)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+	int status;
+
+	mlog(ML_BASTS, "AST fired for lockres %.*s, level %d => %d\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_level,
+	     lockres->l_requested);
+
+	spin_lock(&lockres->l_lock);
+
+	status = ocfs2_dlm_lock_status(&lockres->l_lksb);
+	if (status) {
+		mlog(ML_ERROR, "lksb status value of %u on lockres %.*s\n",
+		     status, lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		return;
+	}
+
+	mlog_bug_on_msg(lockres->l_requested == DLM_LOCK_IV,
+			"Lockres %.*s, requested ivmode. flags 0x%x\n",
+			lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	/* we're downconverting. */
+	if (lockres->l_requested < lockres->l_level) {
+		if (lockres->l_requested <=
+		    user_highest_compat_lock_level(lockres->l_blocking)) {
+			lockres->l_blocking = DLM_LOCK_NL;
+			lockres->l_flags &= ~USER_LOCK_BLOCKED;
+		}
+	}
+
+	lockres->l_level = lockres->l_requested;
+	lockres->l_requested = DLM_LOCK_IV;
+	lockres->l_flags |= USER_LOCK_ATTACHED;
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
+{
+	struct inode *inode;
+	inode = user_dlm_inode_from_user_lockres(lockres);
+	if (!igrab(inode))
+		BUG();
+}
+
+static void user_dlm_unblock_lock(struct work_struct *work);
+
+static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
+{
+	if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
+		user_dlm_grab_inode_ref(lockres);
+
+		INIT_WORK(&lockres->l_work, user_dlm_unblock_lock);
+
+		queue_work(user_dlm_worker, &lockres->l_work);
+		lockres->l_flags |= USER_LOCK_QUEUED;
+	}
+}
+
+static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
+{
+	int queue = 0;
+
+	if (!(lockres->l_flags & USER_LOCK_BLOCKED))
+		return;
+
+	switch (lockres->l_blocking) {
+	case DLM_LOCK_EX:
+		if (!lockres->l_ex_holders && !lockres->l_ro_holders)
+			queue = 1;
+		break;
+	case DLM_LOCK_PR:
+		if (!lockres->l_ex_holders)
+			queue = 1;
+		break;
+	default:
+		BUG();
+	}
+
+	if (queue)
+		__user_dlm_queue_lockres(lockres);
+}
+
+static void user_bast(struct ocfs2_dlm_lksb *lksb, int level)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+
+	mlog(ML_BASTS, "BAST fired for lockres %.*s, blocking %d, level %d\n",
+	     lockres->l_namelen, lockres->l_name, level, lockres->l_level);
+
+	spin_lock(&lockres->l_lock);
+	lockres->l_flags |= USER_LOCK_BLOCKED;
+	if (level > lockres->l_blocking)
+		lockres->l_blocking = level;
+
+	__user_dlm_queue_lockres(lockres);
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+static void user_unlock_ast(struct ocfs2_dlm_lksb *lksb, int status)
+{
+	struct user_lock_res *lockres = user_lksb_to_lock_res(lksb);
+
+	mlog(ML_BASTS, "UNLOCK AST fired for lockres %.*s, flags 0x%x\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	if (status)
+		mlog(ML_ERROR, "dlm returns status %d\n", status);
+
+	spin_lock(&lockres->l_lock);
+	/* The teardown flag gets set early during the unlock process,
+	 * so test the cancel flag to make sure that this ast isn't
+	 * for a concurrent cancel. */
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
+	    && !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
+		lockres->l_level = DLM_LOCK_IV;
+	} else if (status == DLM_CANCELGRANT) {
+		/* We tried to cancel a convert request, but it was
+		 * already granted. Don't clear the busy flag - the
+		 * ast should've done this already. */
+		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
+		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+		goto out_noclear;
+	} else {
+		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
+		/* Cancel succeeded, we want to re-queue */
+		lockres->l_requested = DLM_LOCK_IV; /* cancel an
+						    * upconvert
+						    * request. */
+		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+		/* we want the unblock thread to look at it again
+		 * now. */
+		if (lockres->l_flags & USER_LOCK_BLOCKED)
+			__user_dlm_queue_lockres(lockres);
+	}
+
+	lockres->l_flags &= ~USER_LOCK_BUSY;
+out_noclear:
+	spin_unlock(&lockres->l_lock);
+
+	wake_up(&lockres->l_event);
+}
+
+/*
+ * This is the userdlmfs locking protocol version.
+ *
+ * See fs/ocfs2/dlmglue.c for more details on locking versions.
+ */
+static struct ocfs2_locking_protocol user_dlm_lproto = {
+	.lp_max_version = {
+		.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+		.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+	},
+	.lp_lock_ast		= user_ast,
+	.lp_blocking_ast	= user_bast,
+	.lp_unlock_ast		= user_unlock_ast,
+};
+
+static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
+{
+	struct inode *inode;
+	inode = user_dlm_inode_from_user_lockres(lockres);
+	iput(inode);
+}
+
+static void user_dlm_unblock_lock(struct work_struct *work)
+{
+	int new_level, status;
+	struct user_lock_res *lockres =
+		container_of(work, struct user_lock_res, l_work);
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	mlog(0, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
+
+	spin_lock(&lockres->l_lock);
+
+	mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
+			"Lockres %.*s, flags 0x%x\n",
+			lockres->l_namelen, lockres->l_name, lockres->l_flags);
+
+	/* notice that we don't clear USER_LOCK_BLOCKED here. If it's
+	 * set, we want user_ast clear it. */
+	lockres->l_flags &= ~USER_LOCK_QUEUED;
+
+	/* It's valid to get here and no longer be blocked - if we get
+	 * several basts in a row, we might be queued by the first
+	 * one, the unblock thread might run and clear the queued
+	 * flag, and finally we might get another bast which re-queues
+	 * us before our ast for the downconvert is called. */
+	if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
+		mlog(ML_BASTS, "lockres %.*s USER_LOCK_BLOCKED\n",
+		     lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		goto drop_ref;
+	}
+
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_TEARDOWN\n",
+		     lockres->l_namelen, lockres->l_name);
+		spin_unlock(&lockres->l_lock);
+		goto drop_ref;
+	}
+
+	if (lockres->l_flags & USER_LOCK_BUSY) {
+		if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
+			mlog(ML_BASTS, "lockres %.*s USER_LOCK_IN_CANCEL\n",
+			     lockres->l_namelen, lockres->l_name);
+			spin_unlock(&lockres->l_lock);
+			goto drop_ref;
+		}
+
+		lockres->l_flags |= USER_LOCK_IN_CANCEL;
+		spin_unlock(&lockres->l_lock);
+
+		status = ocfs2_dlm_unlock(conn, &lockres->l_lksb,
+					  DLM_LKF_CANCEL);
+		if (status)
+			user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
+		goto drop_ref;
+	}
+
+	/* If there are still incompat holders, we can exit safely
+	 * without worrying about re-queueing this lock as that will
+	 * happen on the last call to user_cluster_unlock. */
+	if ((lockres->l_blocking == DLM_LOCK_EX)
+	    && (lockres->l_ex_holders || lockres->l_ro_holders)) {
+		spin_unlock(&lockres->l_lock);
+		mlog(ML_BASTS, "lockres %.*s, EX/PR Holders %u,%u\n",
+		     lockres->l_namelen, lockres->l_name,
+		     lockres->l_ex_holders, lockres->l_ro_holders);
+		goto drop_ref;
+	}
+
+	if ((lockres->l_blocking == DLM_LOCK_PR)
+	    && lockres->l_ex_holders) {
+		spin_unlock(&lockres->l_lock);
+		mlog(ML_BASTS, "lockres %.*s, EX Holders %u\n",
+		     lockres->l_namelen, lockres->l_name,
+		     lockres->l_ex_holders);
+		goto drop_ref;
+	}
+
+	/* yay, we can downconvert now. */
+	new_level = user_highest_compat_lock_level(lockres->l_blocking);
+	lockres->l_requested = new_level;
+	lockres->l_flags |= USER_LOCK_BUSY;
+	mlog(ML_BASTS, "lockres %.*s, downconvert %d => %d\n",
+	     lockres->l_namelen, lockres->l_name, lockres->l_level, new_level);
+	spin_unlock(&lockres->l_lock);
+
+	/* need lock downconvert request now... */
+	status = ocfs2_dlm_lock(conn, new_level, &lockres->l_lksb,
+				DLM_LKF_CONVERT|DLM_LKF_VALBLK,
+				lockres->l_name,
+				lockres->l_namelen);
+	if (status) {
+		user_log_dlm_error("ocfs2_dlm_lock", status, lockres);
+		user_recover_from_dlm_error(lockres);
+	}
+
+drop_ref:
+	user_dlm_drop_inode_ref(lockres);
+}
+
+static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
+					int level)
+{
+	switch(level) {
+	case DLM_LOCK_EX:
+		lockres->l_ex_holders++;
+		break;
+	case DLM_LOCK_PR:
+		lockres->l_ro_holders++;
+		break;
+	default:
+		BUG();
+	}
+}
+
+/* predict what lock level we'll be dropping down to on behalf
+ * of another node, and return true if the currently wanted
+ * level will be compatible with it. */
+static inline int
+user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
+				  int wanted)
+{
+	BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
+
+	return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
+}
+
+int user_dlm_cluster_lock(struct user_lock_res *lockres,
+			  int level,
+			  int lkm_flags)
+{
+	int status, local_flags;
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	if (level != DLM_LOCK_EX &&
+	    level != DLM_LOCK_PR) {
+		mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
+		     lockres->l_namelen, lockres->l_name);
+		status = -EINVAL;
+		goto bail;
+	}
+
+	mlog(ML_BASTS, "lockres %.*s, level %d, flags = 0x%x\n",
+	     lockres->l_namelen, lockres->l_name, level, lkm_flags);
+
+again:
+	if (signal_pending(current)) {
+		status = -ERESTARTSYS;
+		goto bail;
+	}
+
+	spin_lock(&lockres->l_lock);
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		spin_unlock(&lockres->l_lock);
+		status = -EAGAIN;
+		goto bail;
+	}
+
+	/* We only compare against the currently granted level
+	 * here. If the lock is blocked waiting on a downconvert,
+	 * we'll get caught below. */
+	if ((lockres->l_flags & USER_LOCK_BUSY) &&
+	    (level > lockres->l_level)) {
+		/* is someone sitting in dlm_lock? If so, wait on
+		 * them. */
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_busy_lock(lockres);
+		goto again;
+	}
+
+	if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
+	    (!user_may_continue_on_blocked_lock(lockres, level))) {
+		/* is the lock is currently blocked on behalf of
+		 * another node */
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_blocked_lock(lockres);
+		goto again;
+	}
+
+	if (level > lockres->l_level) {
+		local_flags = lkm_flags | DLM_LKF_VALBLK;
+		if (lockres->l_level != DLM_LOCK_IV)
+			local_flags |= DLM_LKF_CONVERT;
+
+		lockres->l_requested = level;
+		lockres->l_flags |= USER_LOCK_BUSY;
+		spin_unlock(&lockres->l_lock);
+
+		BUG_ON(level == DLM_LOCK_IV);
+		BUG_ON(level == DLM_LOCK_NL);
+
+		/* call dlm_lock to upgrade lock now */
+		status = ocfs2_dlm_lock(conn, level, &lockres->l_lksb,
+					local_flags, lockres->l_name,
+					lockres->l_namelen);
+		if (status) {
+			if ((lkm_flags & DLM_LKF_NOQUEUE) &&
+			    (status != -EAGAIN))
+				user_log_dlm_error("ocfs2_dlm_lock",
+						   status, lockres);
+			user_recover_from_dlm_error(lockres);
+			goto bail;
+		}
+
+		user_wait_on_busy_lock(lockres);
+		goto again;
+	}
+
+	user_dlm_inc_holders(lockres, level);
+	spin_unlock(&lockres->l_lock);
+
+	status = 0;
+bail:
+	return status;
+}
+
+static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
+					int level)
+{
+	switch(level) {
+	case DLM_LOCK_EX:
+		BUG_ON(!lockres->l_ex_holders);
+		lockres->l_ex_holders--;
+		break;
+	case DLM_LOCK_PR:
+		BUG_ON(!lockres->l_ro_holders);
+		lockres->l_ro_holders--;
+		break;
+	default:
+		BUG();
+	}
+}
+
+void user_dlm_cluster_unlock(struct user_lock_res *lockres,
+			     int level)
+{
+	if (level != DLM_LOCK_EX &&
+	    level != DLM_LOCK_PR) {
+		mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
+		     lockres->l_namelen, lockres->l_name);
+		return;
+	}
+
+	spin_lock(&lockres->l_lock);
+	user_dlm_dec_holders(lockres, level);
+	__user_dlm_cond_queue_lockres(lockres);
+	spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_write_lvb(struct inode *inode,
+			const char *val,
+			unsigned int len)
+{
+	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+	char *lvb;
+
+	BUG_ON(len > DLM_LVB_LEN);
+
+	spin_lock(&lockres->l_lock);
+
+	BUG_ON(lockres->l_level < DLM_LOCK_EX);
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+	memcpy(lvb, val, len);
+
+	spin_unlock(&lockres->l_lock);
+}
+
+bool user_dlm_read_lvb(struct inode *inode, char *val)
+{
+	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+	char *lvb;
+	bool ret = true;
+
+	spin_lock(&lockres->l_lock);
+
+	BUG_ON(lockres->l_level < DLM_LOCK_PR);
+	if (ocfs2_dlm_lvb_valid(&lockres->l_lksb)) {
+		lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
+		memcpy(val, lvb, DLM_LVB_LEN);
+	} else
+		ret = false;
+
+	spin_unlock(&lockres->l_lock);
+	return ret;
+}
+
+void user_dlm_lock_res_init(struct user_lock_res *lockres,
+			    struct dentry *dentry)
+{
+	memset(lockres, 0, sizeof(*lockres));
+
+	spin_lock_init(&lockres->l_lock);
+	init_waitqueue_head(&lockres->l_event);
+	lockres->l_level = DLM_LOCK_IV;
+	lockres->l_requested = DLM_LOCK_IV;
+	lockres->l_blocking = DLM_LOCK_IV;
+
+	/* should have been checked before getting here. */
+	BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
+
+	memcpy(lockres->l_name,
+	       dentry->d_name.name,
+	       dentry->d_name.len);
+	lockres->l_namelen = dentry->d_name.len;
+}
+
+int user_dlm_destroy_lock(struct user_lock_res *lockres)
+{
+	int status = -EBUSY;
+	struct ocfs2_cluster_connection *conn =
+		cluster_connection_from_user_lockres(lockres);
+
+	mlog(ML_BASTS, "lockres %.*s\n", lockres->l_namelen, lockres->l_name);
+
+	spin_lock(&lockres->l_lock);
+	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
+
+	while (lockres->l_flags & USER_LOCK_BUSY) {
+		spin_unlock(&lockres->l_lock);
+
+		user_wait_on_busy_lock(lockres);
+
+		spin_lock(&lockres->l_lock);
+	}
+
+	if (lockres->l_ro_holders || lockres->l_ex_holders) {
+		lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	status = 0;
+	if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
+		/*
+		 * lock is never requested, leave USER_LOCK_IN_TEARDOWN set
+		 * to avoid new lock request coming in.
+		 */
+		spin_unlock(&lockres->l_lock);
+		goto bail;
+	}
+
+	lockres->l_flags |= USER_LOCK_BUSY;
+	spin_unlock(&lockres->l_lock);
+
+	status = ocfs2_dlm_unlock(conn, &lockres->l_lksb, DLM_LKF_VALBLK);
+	if (status) {
+		spin_lock(&lockres->l_lock);
+		lockres->l_flags &= ~USER_LOCK_IN_TEARDOWN;
+		lockres->l_flags &= ~USER_LOCK_BUSY;
+		spin_unlock(&lockres->l_lock);
+		user_log_dlm_error("ocfs2_dlm_unlock", status, lockres);
+		goto bail;
+	}
+
+	user_wait_on_busy_lock(lockres);
+
+	status = 0;
+bail:
+	return status;
+}
+
+static void user_dlm_recovery_handler_noop(int node_num,
+					   void *recovery_data)
+{
+	/* We ignore recovery events */
+	return;
+}
+
+void user_dlm_set_locking_protocol(void)
+{
+	ocfs2_stack_glue_set_max_proto_version(&user_dlm_lproto.lp_max_version);
+}
+
+struct ocfs2_cluster_connection *user_dlm_register(const struct qstr *name)
+{
+	int rc;
+	struct ocfs2_cluster_connection *conn;
+
+	rc = ocfs2_cluster_connect_agnostic(name->name, name->len,
+					    &user_dlm_lproto,
+					    user_dlm_recovery_handler_noop,
+					    NULL, &conn);
+	if (rc)
+		mlog_errno(rc);
+
+	return rc ? ERR_PTR(rc) : conn;
+}
+
+void user_dlm_unregister(struct ocfs2_cluster_connection *conn)
+{
+	ocfs2_cluster_disconnect(conn, 0);
+}