1 files changed, 688 insertions, 0 deletions

diff --git a/fs/ocfs2/dlmfs/userdlm.c b/fs/ocfs2/dlmfs/userdlm.c
new file mode 100644
index 000000000000..0499e3fb7bdb
--- /dev/null
+++ b/fs/ocfs2/dlmfs/userdlm.c
@@ -0,0 +1,688 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * 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.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/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);
+
+        /* 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);
+}
+
+ssize_t user_dlm_read_lvb(struct inode *inode,
+                          char *val,
+                          unsigned int len)
+{
+        struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+        char *lvb;
+        ssize_t ret = len;
+
+        BUG_ON(len > DLM_LVB_LEN);
+
+        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, len);
+        } else
+                ret = 0;
+
+        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);
+                return 0;
+        }
+
+        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) {
+                spin_unlock(&lockres->l_lock);
+                goto bail;
+        }
+
+        status = 0;
+        if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
+                spin_unlock(&lockres->l_lock);
+                goto bail;
+        }
+
+        lockres->l_flags &= ~USER_LOCK_ATTACHED;
+        lockres->l_flags |= USER_LOCK_BUSY;
+        spin_unlock(&lockres->l_lock);
+
+        status = ocfs2_dlm_unlock(conn, &lockres->l_lksb, DLM_LKF_VALBLK);
+        if (status) {
+                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(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);
+}