[PATCH] OCFS2: The Second Oracle Cluster Filesystem

dlmfs: A minimal dlm userspace interface implemented via a virtual
file system.
Most of the OCFS2 tools make use of this to take cluster locks when
doing operations on the file system.

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>

8 files changed, 1617 insertions, 1 deletions

diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
index 628f8a7adb85..d9b0a0691866 100644
--- a/Documentation/filesystems/00-INDEX
+++ b/Documentation/filesystems/00-INDEX
@@ -18,6 +18,8 @@ cramfs.txt
         - info on the cram filesystem for small storage (ROMs etc)
 devfs/
         - directory containing devfs documentation.
+dlmfs.txt
+        - info on the userspace interface to the OCFS2 DLM.
 ext2.txt
         - info, mount options and specifications for the Ext2 filesystem.
 fat_cvf.txt
diff --git a/Documentation/filesystems/dlmfs.txt b/Documentation/filesystems/dlmfs.txt
new file mode 100644
index 000000000000..9afab845a906
--- /dev/null
+++ b/Documentation/filesystems/dlmfs.txt
@@ -0,0 +1,130 @@
+dlmfs
+==================
+A minimal DLM userspace interface implemented via a virtual file
+system.
+
+dlmfs is built with OCFS2 as it requires most of its infrastructure.
+
+Project web page:    http://oss.oracle.com/projects/ocfs2
+Tools web page:      http://oss.oracle.com/projects/ocfs2-tools
+OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
+
+All code copyright 2005 Oracle except when otherwise noted.
+
+CREDITS
+=======
+
+Some code taken from ramfs which is Copyright (C) 2000 Linus Torvalds
+and Transmeta Corp.
+
+Mark Fasheh <mark.fasheh@oracle.com>
+
+Caveats
+=======
+- Right now it only works with the OCFS2 DLM, though support for other
+  DLM implementations should not be a major issue.
+
+Mount options
+=============
+None
+
+Usage
+=====
+
+If you're just interested in OCFS2, then please see ocfs2.txt. The
+rest of this document will be geared towards those who want to use
+dlmfs for easy to setup and easy to use clustered locking in
+userspace.
+
+Setup
+=====
+
+dlmfs requires that the OCFS2 cluster infrastructure be in
+place. Please download ocfs2-tools from the above url and configure a
+cluster.
+
+You'll want to start heartbeating on a volume which all the nodes in
+your lockspace can access. The easiest way to do this is via
+ocfs2_hb_ctl (distributed with ocfs2-tools). Right now it requires
+that an OCFS2 file system be in place so that it can automatically
+find it's heartbeat area, though it will eventually support heartbeat
+against raw disks.
+
+Please see the ocfs2_hb_ctl and mkfs.ocfs2 manual pages distributed
+with ocfs2-tools.
+
+Once you're heartbeating, DLM lock 'domains' can be easily created /
+destroyed and locks within them accessed.
+
+Locking
+=======
+
+Users may access dlmfs via standard file system calls, or they can use
+'libo2dlm' (distributed with ocfs2-tools) which abstracts the file
+system calls and presents a more traditional locking api.
+
+dlmfs handles lock caching automatically for the user, so a lock
+request for an already acquired lock will not generate another DLM
+call. Userspace programs are assumed to handle their own local
+locking.
+
+Two levels of locks are supported - Shared Read, and Exlcusive.
+Also supported is a Trylock operation.
+
+For information on the libo2dlm interface, please see o2dlm.h,
+distributed with ocfs2-tools.
+
+Lock value blocks can be read and written to a resource via read(2)
+and write(2) against the fd obtained via your open(2) call. The
+maximum currently supported LVB length is 64 bytes (though that is an
+OCFS2 DLM limitation). Through this mechanism, users of dlmfs can share
+small amounts of data amongst their nodes.
+
+mkdir(2) signals dlmfs to join a domain (which will have the same name
+as the resulting directory)
+
+rmdir(2) signals dlmfs to leave the domain
+
+Locks for a given domain are represented by regular inodes inside the
+domain directory.  Locking against them is done via the open(2) system
+call.
+
+The open(2) call will not return until your lock has been granted or
+an error has occurred, unless it has been instructed to do a trylock
+operation. If the lock succeeds, you'll get an fd.
+
+open(2) with O_CREAT to ensure the resource inode is created - dlmfs does
+not automatically create inodes for existing lock resources.
+
+Open Flag     Lock Request Type
+---------     -----------------
+O_RDONLY      Shared Read
+O_RDWR        Exclusive
+
+Open Flag     Resulting Locking Behavior
+---------     --------------------------
+O_NONBLOCK    Trylock operation
+
+You must provide exactly one of O_RDONLY or O_RDWR.
+
+If O_NONBLOCK is also provided and the trylock operation was valid but
+could not lock the resource then open(2) will return ETXTBUSY.
+
+close(2) drops the lock associated with your fd.
+
+Modes passed to mkdir(2) or open(2) are adhered to locally. Chown is
+supported locally as well. This means you can use them to restrict
+access to the resources via dlmfs on your local node only.
+
+The resource LVB may be read from the fd in either Shared Read or
+Exclusive modes via the read(2) system call. It can be written via
+write(2) only when open in Exclusive mode.
+
+Once written, an LVB will be visible to other nodes who obtain Read
+Only or higher level locks on the resource.
+
+See Also
+========
+http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
+
+For more information on the VMS distributed locking API.
diff --git a/fs/ocfs2/dlm/Makefile b/fs/ocfs2/dlm/Makefile
index 2a5274bcc8bb..ce3f7c29d270 100644
--- a/fs/ocfs2/dlm/Makefile
+++ b/fs/ocfs2/dlm/Makefile
@@ -1,6 +1,8 @@
 EXTRA_CFLAGS += -Ifs/ocfs2
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2_dlm.o
+obj-$(CONFIG_OCFS2_FS) += ocfs2_dlm.o ocfs2_dlmfs.o
 
 ocfs2_dlm-objs := dlmdomain.o dlmdebug.o dlmthread.o dlmrecovery.o \
         dlmmaster.o dlmast.o dlmconvert.o dlmlock.o dlmunlock.o dlmver.o
+
+ocfs2_dlmfs-objs := userdlm.o dlmfs.o dlmfsver.o
diff --git a/fs/ocfs2/dlm/dlmfs.c b/fs/ocfs2/dlm/dlmfs.c
new file mode 100644
index 000000000000..dd2d24dc25e0
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmfs.c
@@ -0,0 +1,640 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmfs.c
+ *
+ * Code which implements the kernel side of a minimal userspace
+ * interface to our DLM. This file handles the virtual file system
+ * used for communication with userspace. Credit should go to ramfs,
+ * which was a template for the fs side of this module.
+ *
+ * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
+ *
+ * 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.
+ */
+
+/* Simple VFS hooks based on: */
+/*
+ * Resizable simple ram filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ *               2000 Transmeta Corp.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/smp_lock.h>
+#include <linux/backing-dev.h>
+
+#include <asm/uaccess.h>
+
+
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+
+#include "userdlm.h"
+
+#include "dlmfsver.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "cluster/masklog.h"
+
+static struct super_operations dlmfs_ops;
+static struct file_operations dlmfs_file_operations;
+static struct inode_operations dlmfs_dir_inode_operations;
+static struct inode_operations dlmfs_root_inode_operations;
+static struct inode_operations dlmfs_file_inode_operations;
+static kmem_cache_t *dlmfs_inode_cache;
+
+struct workqueue_struct *user_dlm_worker;
+
+/*
+ * decodes a set of open flags into a valid lock level and a set of flags.
+ * returns < 0 if we have invalid flags
+ * flags which mean something to us:
+ * O_RDONLY -> PRMODE level
+ * O_WRONLY -> EXMODE level
+ *
+ * O_NONBLOCK -> LKM_NOQUEUE
+ */
+static int dlmfs_decode_open_flags(int open_flags,
+                                   int *level,
+                                   int *flags)
+{
+        if (open_flags & (O_WRONLY|O_RDWR))
+                *level = LKM_EXMODE;
+        else
+                *level = LKM_PRMODE;
+
+        *flags = 0;
+        if (open_flags & O_NONBLOCK)
+                *flags |= LKM_NOQUEUE;
+
+        return 0;
+}
+
+static int dlmfs_file_open(struct inode *inode,
+                           struct file *file)
+{
+        int status, level, flags;
+        struct dlmfs_filp_private *fp = NULL;
+        struct dlmfs_inode_private *ip;
+
+        if (S_ISDIR(inode->i_mode))
+                BUG();
+
+        mlog(0, "open called on inode %lu, flags 0x%x\n", inode->i_ino,
+                file->f_flags);
+
+        status = dlmfs_decode_open_flags(file->f_flags, &level, &flags);
+        if (status < 0)
+                goto bail;
+
+        /* We don't want to honor O_APPEND at read/write time as it
+         * doesn't make sense for LVB writes. */
+        file->f_flags &= ~O_APPEND;
+
+        fp = kmalloc(sizeof(*fp), GFP_KERNEL);
+        if (!fp) {
+                status = -ENOMEM;
+                goto bail;
+        }
+        fp->fp_lock_level = level;
+
+        ip = DLMFS_I(inode);
+
+        status = user_dlm_cluster_lock(&ip->ip_lockres, level, flags);
+        if (status < 0) {
+                /* this is a strange error to return here but I want
+                 * to be able userspace to be able to distinguish a
+                 * valid lock request from one that simply couldn't be
+                 * granted. */
+                if (flags & LKM_NOQUEUE && status == -EAGAIN)
+                        status = -ETXTBSY;
+                kfree(fp);
+                goto bail;
+        }
+
+        file->private_data = fp;
+bail:
+        return status;
+}
+
+static int dlmfs_file_release(struct inode *inode,
+                              struct file *file)
+{
+        int level, status;
+        struct dlmfs_inode_private *ip = DLMFS_I(inode);
+        struct dlmfs_filp_private *fp =
+                (struct dlmfs_filp_private *) file->private_data;
+
+        if (S_ISDIR(inode->i_mode))
+                BUG();
+
+        mlog(0, "close called on inode %lu\n", inode->i_ino);
+
+        status = 0;
+        if (fp) {
+                level = fp->fp_lock_level;
+                if (level != LKM_IVMODE)
+                        user_dlm_cluster_unlock(&ip->ip_lockres, level);
+
+                kfree(fp);
+                file->private_data = NULL;
+        }
+
+        return 0;
+}
+
+static ssize_t dlmfs_file_read(struct file *filp,
+                               char __user *buf,
+                               size_t count,
+                               loff_t *ppos)
+{
+        int bytes_left;
+        ssize_t readlen;
+        char *lvb_buf;
+        struct inode *inode = filp->f_dentry->d_inode;
+
+        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
+                inode->i_ino, count, *ppos);
+
+        if (*ppos >= i_size_read(inode))
+                return 0;
+
+        if (!count)
+                return 0;
+
+        if (!access_ok(VERIFY_WRITE, buf, count))
+                return -EFAULT;
+
+        /* don't read past the lvb */
+        if ((count + *ppos) > i_size_read(inode))
+                readlen = i_size_read(inode) - *ppos;
+        else
+                readlen = count - *ppos;
+
+        lvb_buf = kmalloc(readlen, GFP_KERNEL);
+        if (!lvb_buf)
+                return -ENOMEM;
+
+        user_dlm_read_lvb(inode, lvb_buf, readlen);
+        bytes_left = __copy_to_user(buf, lvb_buf, readlen);
+        readlen -= bytes_left;
+
+        kfree(lvb_buf);
+
+        *ppos = *ppos + readlen;
+
+        mlog(0, "read %zd bytes\n", readlen);
+        return readlen;
+}
+
+static ssize_t dlmfs_file_write(struct file *filp,
+                                const char __user *buf,
+                                size_t count,
+                                loff_t *ppos)
+{
+        int bytes_left;
+        ssize_t writelen;
+        char *lvb_buf;
+        struct inode *inode = filp->f_dentry->d_inode;
+
+        mlog(0, "inode %lu, count = %zu, *ppos = %llu\n",
+                inode->i_ino, count, *ppos);
+
+        if (*ppos >= i_size_read(inode))
+                return -ENOSPC;
+
+        if (!count)
+                return 0;
+
+        if (!access_ok(VERIFY_READ, buf, count))
+                return -EFAULT;
+
+        /* don't write past the lvb */
+        if ((count + *ppos) > i_size_read(inode))
+                writelen = i_size_read(inode) - *ppos;
+        else
+                writelen = count - *ppos;
+
+        lvb_buf = kmalloc(writelen, GFP_KERNEL);
+        if (!lvb_buf)
+                return -ENOMEM;
+
+        bytes_left = copy_from_user(lvb_buf, buf, writelen);
+        writelen -= bytes_left;
+        if (writelen)
+                user_dlm_write_lvb(inode, lvb_buf, writelen);
+
+        kfree(lvb_buf);
+
+        *ppos = *ppos + writelen;
+        mlog(0, "wrote %zd bytes\n", writelen);
+        return writelen;
+}
+
+static void dlmfs_init_once(void *foo,
+                            kmem_cache_t *cachep,
+                            unsigned long flags)
+{
+        struct dlmfs_inode_private *ip =
+                (struct dlmfs_inode_private *) foo;
+
+        if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+            SLAB_CTOR_CONSTRUCTOR) {
+                ip->ip_dlm = NULL;
+                ip->ip_parent = NULL;
+
+                inode_init_once(&ip->ip_vfs_inode);
+        }
+}
+
+static struct inode *dlmfs_alloc_inode(struct super_block *sb)
+{
+        struct dlmfs_inode_private *ip;
+
+        ip = kmem_cache_alloc(dlmfs_inode_cache, SLAB_NOFS);
+        if (!ip)
+                return NULL;
+
+        return &ip->ip_vfs_inode;
+}
+
+static void dlmfs_destroy_inode(struct inode *inode)
+{
+        kmem_cache_free(dlmfs_inode_cache, DLMFS_I(inode));
+}
+
+static void dlmfs_clear_inode(struct inode *inode)
+{
+        int status;
+        struct dlmfs_inode_private *ip;
+
+        if (!inode)
+                return;
+
+        mlog(0, "inode %lu\n", inode->i_ino);
+
+        ip = DLMFS_I(inode);
+
+        if (S_ISREG(inode->i_mode)) {
+                status = user_dlm_destroy_lock(&ip->ip_lockres);
+                if (status < 0)
+                        mlog_errno(status);
+                iput(ip->ip_parent);
+                goto clear_fields;
+        }
+
+        mlog(0, "we're a directory, ip->ip_dlm = 0x%p\n", ip->ip_dlm);
+        /* we must be a directory. If required, lets unregister the
+         * dlm context now. */
+        if (ip->ip_dlm)
+                user_dlm_unregister_context(ip->ip_dlm);
+clear_fields:
+        ip->ip_parent = NULL;
+        ip->ip_dlm = NULL;
+}
+
+static struct backing_dev_info dlmfs_backing_dev_info = {
+        .ra_pages       = 0,    /* No readahead */
+        .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+};
+
+static struct inode *dlmfs_get_root_inode(struct super_block *sb)
+{
+        struct inode *inode = new_inode(sb);
+        int mode = S_IFDIR | 0755;
+        struct dlmfs_inode_private *ip;
+
+        if (inode) {
+                ip = DLMFS_I(inode);
+
+                inode->i_mode = mode;
+                inode->i_uid = current->fsuid;
+                inode->i_gid = current->fsgid;
+                inode->i_blksize = PAGE_CACHE_SIZE;
+                inode->i_blocks = 0;
+                inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+                inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                inode->i_nlink++;
+
+                inode->i_fop = &simple_dir_operations;
+                inode->i_op = &dlmfs_root_inode_operations;
+        }
+
+        return inode;
+}
+
+static struct inode *dlmfs_get_inode(struct inode *parent,
+                                     struct dentry *dentry,
+                                     int mode)
+{
+        struct super_block *sb = parent->i_sb;
+        struct inode * inode = new_inode(sb);
+        struct dlmfs_inode_private *ip;
+
+        if (!inode)
+                return NULL;
+
+        inode->i_mode = mode;
+        inode->i_uid = current->fsuid;
+        inode->i_gid = current->fsgid;
+        inode->i_blksize = PAGE_CACHE_SIZE;
+        inode->i_blocks = 0;
+        inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+
+        ip = DLMFS_I(inode);
+        ip->ip_dlm = DLMFS_I(parent)->ip_dlm;
+
+        switch (mode & S_IFMT) {
+        default:
+                /* for now we don't support anything other than
+                 * directories and regular files. */
+                BUG();
+                break;
+        case S_IFREG:
+                inode->i_op = &dlmfs_file_inode_operations;
+                inode->i_fop = &dlmfs_file_operations;
+
+                i_size_write(inode,  DLM_LVB_LEN);
+
+                user_dlm_lock_res_init(&ip->ip_lockres, dentry);
+
+                /* released at clear_inode time, this insures that we
+                 * get to drop the dlm reference on each lock *before*
+                 * we call the unregister code for releasing parent
+                 * directories. */
+                ip->ip_parent = igrab(parent);
+                BUG_ON(!ip->ip_parent);
+                break;
+        case S_IFDIR:
+                inode->i_op = &dlmfs_dir_inode_operations;
+                inode->i_fop = &simple_dir_operations;
+
+                /* directory inodes start off with i_nlink ==
+                 * 2 (for "." entry) */
+                inode->i_nlink++;
+                break;
+        }
+
+        if (parent->i_mode & S_ISGID) {
+                inode->i_gid = parent->i_gid;
+                if (S_ISDIR(mode))
+                        inode->i_mode |= S_ISGID;
+        }
+
+        return inode;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+/* SMP-safe */
+static int dlmfs_mkdir(struct inode * dir,
+                       struct dentry * dentry,
+                       int mode)
+{
+        int status;
+        struct inode *inode = NULL;
+        struct qstr *domain = &dentry->d_name;
+        struct dlmfs_inode_private *ip;
+        struct dlm_ctxt *dlm;
+
+        mlog(0, "mkdir %.*s\n", domain->len, domain->name);
+
+        /* verify that we have a proper domain */
+        if (domain->len >= O2NM_MAX_NAME_LEN) {
+                status = -EINVAL;
+                mlog(ML_ERROR, "invalid domain name for directory.\n");
+                goto bail;
+        }
+
+        inode = dlmfs_get_inode(dir, dentry, mode | S_IFDIR);
+        if (!inode) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        ip = DLMFS_I(inode);
+
+        dlm = user_dlm_register_context(domain);
+        if (IS_ERR(dlm)) {
+                status = PTR_ERR(dlm);
+                mlog(ML_ERROR, "Error %d could not register domain \"%.*s\"\n",
+                     status, domain->len, domain->name);
+                goto bail;
+        }
+        ip->ip_dlm = dlm;
+
+        dir->i_nlink++;
+        d_instantiate(dentry, inode);
+        dget(dentry);   /* Extra count - pin the dentry in core */
+
+        status = 0;
+bail:
+        if (status < 0)
+                iput(inode);
+        return status;
+}
+
+static int dlmfs_create(struct inode *dir,
+                        struct dentry *dentry,
+                        int mode,
+                        struct nameidata *nd)
+{
+        int status = 0;
+        struct inode *inode;
+        struct qstr *name = &dentry->d_name;
+
+        mlog(0, "create %.*s\n", name->len, name->name);
+
+        /* verify name is valid and doesn't contain any dlm reserved
+         * characters */
+        if (name->len >= USER_DLM_LOCK_ID_MAX_LEN ||
+            name->name[0] == '$') {
+                status = -EINVAL;
+                mlog(ML_ERROR, "invalid lock name, %.*s\n", name->len,
+                     name->name);
+                goto bail;
+        }
+
+        inode = dlmfs_get_inode(dir, dentry, mode | S_IFREG);
+        if (!inode) {
+                status = -ENOMEM;
+                mlog_errno(status);
+                goto bail;
+        }
+
+        d_instantiate(dentry, inode);
+        dget(dentry);   /* Extra count - pin the dentry in core */
+bail:
+        return status;
+}
+
+static int dlmfs_unlink(struct inode *dir,
+                        struct dentry *dentry)
+{
+        int status;
+        struct inode *inode = dentry->d_inode;
+
+        mlog(0, "unlink inode %lu\n", inode->i_ino);
+
+        /* if there are no current holders, or none that are waiting
+         * to acquire a lock, this basically destroys our lockres. */
+        status = user_dlm_destroy_lock(&DLMFS_I(inode)->ip_lockres);
+        if (status < 0) {
+                mlog(ML_ERROR, "unlink %.*s, error %d from destroy\n",
+                     dentry->d_name.len, dentry->d_name.name, status);
+                goto bail;
+        }
+        status = simple_unlink(dir, dentry);
+bail:
+        return status;
+}
+
+static int dlmfs_fill_super(struct super_block * sb,
+                            void * data,
+                            int silent)
+{
+        struct inode * inode;
+        struct dentry * root;
+
+        sb->s_maxbytes = MAX_LFS_FILESIZE;
+        sb->s_blocksize = PAGE_CACHE_SIZE;
+        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+        sb->s_magic = DLMFS_MAGIC;
+        sb->s_op = &dlmfs_ops;
+        inode = dlmfs_get_root_inode(sb);
+        if (!inode)
+                return -ENOMEM;
+
+        root = d_alloc_root(inode);
+        if (!root) {
+                iput(inode);
+                return -ENOMEM;
+        }
+        sb->s_root = root;
+        return 0;
+}
+
+static struct file_operations dlmfs_file_operations = {
+        .open           = dlmfs_file_open,
+        .release        = dlmfs_file_release,
+        .read           = dlmfs_file_read,
+        .write          = dlmfs_file_write,
+};
+
+static struct inode_operations dlmfs_dir_inode_operations = {
+        .create         = dlmfs_create,
+        .lookup         = simple_lookup,
+        .unlink         = dlmfs_unlink,
+};
+
+/* this way we can restrict mkdir to only the toplevel of the fs. */
+static struct inode_operations dlmfs_root_inode_operations = {
+        .lookup         = simple_lookup,
+        .mkdir          = dlmfs_mkdir,
+        .rmdir          = simple_rmdir,
+};
+
+static struct super_operations dlmfs_ops = {
+        .statfs         = simple_statfs,
+        .alloc_inode    = dlmfs_alloc_inode,
+        .destroy_inode  = dlmfs_destroy_inode,
+        .clear_inode    = dlmfs_clear_inode,
+        .drop_inode     = generic_delete_inode,
+};
+
+static struct inode_operations dlmfs_file_inode_operations = {
+        .getattr        = simple_getattr,
+};
+
+static struct super_block *dlmfs_get_sb(struct file_system_type *fs_type,
+        int flags, const char *dev_name, void *data)
+{
+        return get_sb_nodev(fs_type, flags, data, dlmfs_fill_super);
+}
+
+static struct file_system_type dlmfs_fs_type = {
+        .owner          = THIS_MODULE,
+        .name           = "ocfs2_dlmfs",
+        .get_sb         = dlmfs_get_sb,
+        .kill_sb        = kill_litter_super,
+};
+
+static int __init init_dlmfs_fs(void)
+{
+        int status;
+        int cleanup_inode = 0, cleanup_worker = 0;
+
+        dlmfs_print_version();
+
+        dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
+                                sizeof(struct dlmfs_inode_private),
+                                0, SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT,
+                                dlmfs_init_once, NULL);
+        if (!dlmfs_inode_cache)
+                return -ENOMEM;
+        cleanup_inode = 1;
+
+        user_dlm_worker = create_singlethread_workqueue("user_dlm");
+        if (!user_dlm_worker) {
+                status = -ENOMEM;
+                goto bail;
+        }
+        cleanup_worker = 1;
+
+        status = register_filesystem(&dlmfs_fs_type);
+bail:
+        if (status) {
+                if (cleanup_inode)
+                        kmem_cache_destroy(dlmfs_inode_cache);
+                if (cleanup_worker)
+                        destroy_workqueue(user_dlm_worker);
+        } else
+                printk("OCFS2 User DLM kernel interface loaded\n");
+        return status;
+}
+
+static void __exit exit_dlmfs_fs(void)
+{
+        unregister_filesystem(&dlmfs_fs_type);
+
+        flush_workqueue(user_dlm_worker);
+        destroy_workqueue(user_dlm_worker);
+
+        if (kmem_cache_destroy(dlmfs_inode_cache))
+                printk(KERN_INFO "dlmfs_inode_cache: not all structures "
+                       "were freed\n");
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+
+module_init(init_dlmfs_fs)
+module_exit(exit_dlmfs_fs)
diff --git a/fs/ocfs2/dlm/dlmfsver.c b/fs/ocfs2/dlm/dlmfsver.c
new file mode 100644
index 000000000000..d2be3ad841f9
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmfsver.c
@@ -0,0 +1,42 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmfsver.c
+ *
+ * version string
+ *
+ * Copyright (C) 2002, 2005 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/module.h>
+#include <linux/kernel.h>
+
+#include "dlmfsver.h"
+
+#define DLM_BUILD_VERSION "1.3.3"
+
+#define VERSION_STR "OCFS2 DLMFS " DLM_BUILD_VERSION
+
+void dlmfs_print_version(void)
+{
+        printk(KERN_INFO "%s\n", VERSION_STR);
+}
+
+MODULE_DESCRIPTION(VERSION_STR);
+
+MODULE_VERSION(DLM_BUILD_VERSION);
diff --git a/fs/ocfs2/dlm/dlmfsver.h b/fs/ocfs2/dlm/dlmfsver.h
new file mode 100644
index 000000000000..f35eadbed25c
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmfsver.h
@@ -0,0 +1,31 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmver.h
+ *
+ * Function prototypes
+ *
+ * Copyright (C) 2005 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.
+ */
+
+#ifndef DLMFS_VER_H
+#define DLMFS_VER_H
+
+void dlmfs_print_version(void);
+
+#endif /* DLMFS_VER_H */
diff --git a/fs/ocfs2/dlm/userdlm.c b/fs/ocfs2/dlm/userdlm.c
new file mode 100644
index 000000000000..e1fdd288796e
--- /dev/null
+++ b/fs/ocfs2/dlm/userdlm.c
@@ -0,0 +1,658 @@
+/* -*- 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 <asm/signal.h>
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/crc32.h>
+
+
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+#include "cluster/tcp.h"
+
+#include "dlmapi.h"
+
+#include "userdlm.h"
+
+#define MLOG_MASK_PREFIX ML_DLMFS
+#include "cluster/masklog.h"
+
+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 dlm_ctxt *
+dlm_ctxt_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_dlm;
+}
+
+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 \"%s\" while calling %s on "  \
+                "resource %s: %s\n", dlm_errname(_stat), _func, \
+                _lockres->l_name, dlm_errmsg(_stat));           \
+} 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 = LKM_EXMODE;
+
+        if (level == LKM_EXMODE)
+                new_level = LKM_NLMODE;
+        else if (level == LKM_PRMODE)
+                new_level = LKM_PRMODE;
+        return new_level;
+}
+
+static void user_ast(void *opaque)
+{
+        struct user_lock_res *lockres = opaque;
+        struct dlm_lockstatus *lksb;
+
+        mlog(0, "AST fired for lockres %s\n", lockres->l_name);
+
+        spin_lock(&lockres->l_lock);
+
+        lksb = &(lockres->l_lksb);
+        if (lksb->status != DLM_NORMAL) {
+                mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
+                     lksb->status, lockres->l_name);
+                spin_unlock(&lockres->l_lock);
+                return;
+        }
+
+        /* 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 = LKM_NLMODE;
+                        lockres->l_flags &= ~USER_LOCK_BLOCKED;
+                }
+        }
+
+        lockres->l_level = lockres->l_requested;
+        lockres->l_requested = LKM_IVMODE;
+        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(void *opaque);
+
+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,
+                          lockres);
+
+                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 LKM_EXMODE:
+                if (!lockres->l_ex_holders && !lockres->l_ro_holders)
+                        queue = 1;
+                break;
+        case LKM_PRMODE:
+                if (!lockres->l_ex_holders)
+                        queue = 1;
+                break;
+        default:
+                BUG();
+        }
+
+        if (queue)
+                __user_dlm_queue_lockres(lockres);
+}
+
+static void user_bast(void *opaque, int level)
+{
+        struct user_lock_res *lockres = opaque;
+
+        mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
+                lockres->l_name, 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(void *opaque, enum dlm_status status)
+{
+        struct user_lock_res *lockres = opaque;
+
+        mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
+
+        if (status != DLM_NORMAL)
+                mlog(ML_ERROR, "Dlm returns status %d\n", status);
+
+        spin_lock(&lockres->l_lock);
+        if (lockres->l_flags & USER_LOCK_IN_TEARDOWN)
+                lockres->l_level = LKM_IVMODE;
+        else {
+                lockres->l_requested = LKM_IVMODE; /* cancel an
+                                                    * upconvert
+                                                    * request. */
+                lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+                /* we want the unblock thread to look at it again
+                 * now. */
+                __user_dlm_queue_lockres(lockres);
+        }
+
+        lockres->l_flags &= ~USER_LOCK_BUSY;
+        spin_unlock(&lockres->l_lock);
+
+        wake_up(&lockres->l_event);
+}
+
+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(void *opaque)
+{
+        int new_level, status;
+        struct user_lock_res *lockres = (struct user_lock_res *) opaque;
+        struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+        mlog(0, "processing lockres %s\n", lockres->l_name);
+
+        spin_lock(&lockres->l_lock);
+
+        BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
+        BUG_ON(!(lockres->l_flags & USER_LOCK_QUEUED));
+
+        /* notice that we don't clear USER_LOCK_BLOCKED here. That's
+         * for user_ast to do. */
+        lockres->l_flags &= ~USER_LOCK_QUEUED;
+
+        if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
+                mlog(0, "lock is in teardown so we do nothing\n");
+                spin_unlock(&lockres->l_lock);
+                goto drop_ref;
+        }
+
+        if (lockres->l_flags & USER_LOCK_BUSY) {
+                mlog(0, "BUSY flag detected...\n");
+                if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
+                        spin_unlock(&lockres->l_lock);
+                        goto drop_ref;
+                }
+
+                lockres->l_flags |= USER_LOCK_IN_CANCEL;
+                spin_unlock(&lockres->l_lock);
+
+                status = dlmunlock(dlm,
+                                   &lockres->l_lksb,
+                                   LKM_CANCEL,
+                                   user_unlock_ast,
+                                   lockres);
+                if (status == DLM_CANCELGRANT) {
+                        /* If we got this, then the ast was fired
+                         * before we could cancel. We cleanup our
+                         * state, and restart the function. */
+                        spin_lock(&lockres->l_lock);
+                        lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
+                        spin_unlock(&lockres->l_lock);
+                } else if (status != DLM_NORMAL)
+                        user_log_dlm_error("dlmunlock", 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 == LKM_EXMODE)
+            && (lockres->l_ex_holders || lockres->l_ro_holders)) {
+                spin_unlock(&lockres->l_lock);
+                mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
+                        lockres->l_ro_holders, lockres->l_ex_holders);
+                goto drop_ref;
+        }
+
+        if ((lockres->l_blocking == LKM_PRMODE)
+            && lockres->l_ex_holders) {
+                spin_unlock(&lockres->l_lock);
+                mlog(0, "can't downconvert for pr: ex = %u\n",
+                        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(0, "Downconvert lock from %d to %d\n",
+                lockres->l_level, new_level);
+        spin_unlock(&lockres->l_lock);
+
+        /* need lock downconvert request now... */
+        status = dlmlock(dlm,
+                         new_level,
+                         &lockres->l_lksb,
+                         LKM_CONVERT|LKM_VALBLK,
+                         lockres->l_name,
+                         user_ast,
+                         lockres,
+                         user_bast);
+        if (status != DLM_NORMAL) {
+                user_log_dlm_error("dlmlock", 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 LKM_EXMODE:
+                lockres->l_ex_holders++;
+                break;
+        case LKM_PRMODE:
+                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 dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+        if (level != LKM_EXMODE &&
+            level != LKM_PRMODE) {
+                mlog(ML_ERROR, "lockres %s: invalid request!\n",
+                     lockres->l_name);
+                status = -EINVAL;
+                goto bail;
+        }
+
+        mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
+                lockres->l_name,
+                (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
+                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 | LKM_VALBLK;
+                if (lockres->l_level != LKM_IVMODE)
+                        local_flags |= LKM_CONVERT;
+
+                lockres->l_requested = level;
+                lockres->l_flags |= USER_LOCK_BUSY;
+                spin_unlock(&lockres->l_lock);
+
+                BUG_ON(level == LKM_IVMODE);
+                BUG_ON(level == LKM_NLMODE);
+
+                mlog(0, "lock %s, get lock from %d to level = %d\n",
+                        lockres->l_name, lockres->l_level, level);
+
+                /* call dlm_lock to upgrade lock now */
+                status = dlmlock(dlm,
+                                 level,
+                                 &lockres->l_lksb,
+                                 local_flags,
+                                 lockres->l_name,
+                                 user_ast,
+                                 lockres,
+                                 user_bast);
+                if (status != DLM_NORMAL) {
+                        if ((lkm_flags & LKM_NOQUEUE) &&
+                            (status == DLM_NOTQUEUED))
+                                status = -EAGAIN;
+                        else {
+                                user_log_dlm_error("dlmlock", status, lockres);
+                                status = -EINVAL;
+                        }
+                        user_recover_from_dlm_error(lockres);
+                        goto bail;
+                }
+
+                mlog(0, "lock %s, successfull return from dlmlock\n",
+                        lockres->l_name);
+
+                user_wait_on_busy_lock(lockres);
+                goto again;
+        }
+
+        user_dlm_inc_holders(lockres, level);
+        spin_unlock(&lockres->l_lock);
+
+        mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
+                (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
+
+        status = 0;
+bail:
+        return status;
+}
+
+static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
+                                        int level)
+{
+        switch(level) {
+        case LKM_EXMODE:
+                BUG_ON(!lockres->l_ex_holders);
+                lockres->l_ex_holders--;
+                break;
+        case LKM_PRMODE:
+                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 != LKM_EXMODE &&
+            level != LKM_PRMODE) {
+                mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
+                return;
+        }
+
+        mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
+                (level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
+
+        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 = lockres->l_lksb.lvb;
+
+        BUG_ON(len > DLM_LVB_LEN);
+
+        spin_lock(&lockres->l_lock);
+
+        BUG_ON(lockres->l_level < LKM_EXMODE);
+        memcpy(lvb, val, len);
+
+        spin_unlock(&lockres->l_lock);
+}
+
+void user_dlm_read_lvb(struct inode *inode,
+                       char *val,
+                       unsigned int len)
+{
+        struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
+        char *lvb = lockres->l_lksb.lvb;
+
+        BUG_ON(len > DLM_LVB_LEN);
+
+        spin_lock(&lockres->l_lock);
+
+        BUG_ON(lockres->l_level < LKM_PRMODE);
+        memcpy(val, lvb, len);
+
+        spin_unlock(&lockres->l_lock);
+}
+
+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 = LKM_IVMODE;
+        lockres->l_requested = LKM_IVMODE;
+        lockres->l_blocking = LKM_IVMODE;
+
+        /* 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);
+}
+
+int user_dlm_destroy_lock(struct user_lock_res *lockres)
+{
+        int status = -EBUSY;
+        struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
+
+        mlog(0, "asked to destroy %s\n", lockres->l_name);
+
+        spin_lock(&lockres->l_lock);
+        while (lockres->l_flags & USER_LOCK_BUSY) {
+                spin_unlock(&lockres->l_lock);
+
+                mlog(0, "lock %s is busy\n", lockres->l_name);
+
+                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);
+                mlog(0, "lock %s has holders\n", lockres->l_name);
+                goto bail;
+        }
+
+        status = 0;
+        if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
+                spin_unlock(&lockres->l_lock);
+                mlog(0, "lock %s is not attached\n", lockres->l_name);
+                goto bail;
+        }
+
+        lockres->l_flags &= ~USER_LOCK_ATTACHED;
+        lockres->l_flags |= USER_LOCK_BUSY;
+        lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
+        spin_unlock(&lockres->l_lock);
+
+        mlog(0, "unlocking lockres %s\n", lockres->l_name);
+        status = dlmunlock(dlm,
+                           &lockres->l_lksb,
+                           LKM_VALBLK,
+                           user_unlock_ast,
+                           lockres);
+        if (status != DLM_NORMAL) {
+                user_log_dlm_error("dlmunlock", status, lockres);
+                status = -EINVAL;
+                goto bail;
+        }
+
+        user_wait_on_busy_lock(lockres);
+
+        status = 0;
+bail:
+        return status;
+}
+
+struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
+{
+        struct dlm_ctxt *dlm;
+        u32 dlm_key;
+        char *domain;
+
+        domain = kmalloc(name->len + 1, GFP_KERNEL);
+        if (!domain) {
+                mlog_errno(-ENOMEM);
+                return ERR_PTR(-ENOMEM);
+        }
+
+        dlm_key = crc32_le(0, name->name, name->len);
+
+        snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
+
+        dlm = dlm_register_domain(domain, dlm_key);
+        if (IS_ERR(dlm))
+                mlog_errno(PTR_ERR(dlm));
+
+        kfree(domain);
+        return dlm;
+}
+
+void user_dlm_unregister_context(struct dlm_ctxt *dlm)
+{
+        dlm_unregister_domain(dlm);
+}
diff --git a/fs/ocfs2/dlm/userdlm.h b/fs/ocfs2/dlm/userdlm.h
new file mode 100644
index 000000000000..04178bc40b76
--- /dev/null
+++ b/fs/ocfs2/dlm/userdlm.h
@@ -0,0 +1,111 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * userdlm.h
+ *
+ * Userspace dlm defines
+ *
+ * Copyright (C) 2002, 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.
+ */
+
+
+#ifndef USERDLM_H
+#define USERDLM_H
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+/* user_lock_res->l_flags flags. */
+#define USER_LOCK_ATTACHED      (0x00000001) /* have we initialized
+                                               * the lvb */
+#define USER_LOCK_BUSY          (0x00000002) /* we are currently in
+                                               * dlm_lock */
+#define USER_LOCK_BLOCKED       (0x00000004) /* blocked waiting to
+                                              * downconvert*/
+#define USER_LOCK_IN_TEARDOWN   (0x00000008) /* we're currently
+                                              * destroying this
+                                              * lock. */
+#define USER_LOCK_QUEUED        (0x00000010) /* lock is on the
+                                              * workqueue */
+#define USER_LOCK_IN_CANCEL     (0x00000020)
+
+struct user_lock_res {
+        spinlock_t               l_lock;
+
+        int                      l_flags;
+
+#define USER_DLM_LOCK_ID_MAX_LEN  32
+        char                     l_name[USER_DLM_LOCK_ID_MAX_LEN];
+        int                      l_level;
+        unsigned int             l_ro_holders;
+        unsigned int             l_ex_holders;
+        struct dlm_lockstatus    l_lksb;
+
+        int                      l_requested;
+        int                      l_blocking;
+
+        wait_queue_head_t        l_event;
+
+        struct work_struct       l_work;
+};
+
+extern struct workqueue_struct *user_dlm_worker;
+
+void user_dlm_lock_res_init(struct user_lock_res *lockres,
+                            struct dentry *dentry);
+int user_dlm_destroy_lock(struct user_lock_res *lockres);
+int user_dlm_cluster_lock(struct user_lock_res *lockres,
+                          int level,
+                          int lkm_flags);
+void user_dlm_cluster_unlock(struct user_lock_res *lockres,
+                             int level);
+void user_dlm_write_lvb(struct inode *inode,
+                        const char *val,
+                        unsigned int len);
+void user_dlm_read_lvb(struct inode *inode,
+                       char *val,
+                       unsigned int len);
+struct dlm_ctxt *user_dlm_register_context(struct qstr *name);
+void user_dlm_unregister_context(struct dlm_ctxt *dlm);
+
+struct dlmfs_inode_private {
+        struct dlm_ctxt             *ip_dlm;
+
+        struct user_lock_res ip_lockres; /* unused for directories. */
+        struct inode         *ip_parent;
+
+        struct inode         ip_vfs_inode;
+};
+
+static inline struct dlmfs_inode_private *
+DLMFS_I(struct inode *inode)
+{
+        return container_of(inode,
+                            struct dlmfs_inode_private,
+                            ip_vfs_inode);
+}
+
+struct dlmfs_filp_private {
+        int                  fp_lock_level;
+};
+
+#define DLMFS_MAGIC     0x76a9f425
+
+#endif /* USERDLM_H */