Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2: (64 commits)
  ocfs2/net: Add debug interface to o2net
  ocfs2: Only build ocfs2/dlm with the o2cb stack module
  ocfs2/cluster: Get rid of arguments to the timeout routines
  ocfs2: Put tree in MAINTAINERS
  ocfs2: Use BUG_ON
  ocfs2: Convert ocfs2 over to unlocked_ioctl
  ocfs2: Improve rename locking
  fs/ocfs2/aops.c: test for IS_ERR rather than 0
  ocfs2: Add inode stealing for ocfs2_reserve_new_inode
  ocfs2: Add ac_alloc_slot in ocfs2_alloc_context
  ocfs2: Add a new parameter for ocfs2_reserve_suballoc_bits
  ocfs2: Enable cross extent block merge.
  ocfs2: Add support for cross extent block
  ocfs2: Move /sys/o2cb to /sys/fs/o2cb
  sysfs: Allow removal of symlinks in the sysfs root
  ocfs2:  Reconnect after idle time out.
  ocfs2/dlm: Cleanup lockres print
  ocfs2/dlm: Fix lockname in lockres print function
  ocfs2/dlm: Move dlm_print_one_mle() from dlmmaster.c to dlmdebug.c
  ocfs2/dlm: Dumps the purgelist into a debugfs file
  ...

47 files changed, 5800 insertions, 1042 deletions

diff --git a/Documentation/ABI/obsolete/o2cb b/Documentation/ABI/obsolete/o2cb
new file mode 100644
index 00000000000..9c49d8e6c0c
--- /dev/null
+++ b/Documentation/ABI/obsolete/o2cb
@@ -0,0 +1,11 @@
+What:		/sys/o2cb symlink
+Date:		Dec 2005
+KernelVersion:	2.6.16
+Contact:	ocfs2-devel@oss.oracle.com
+Description:	This is a symlink: /sys/o2cb to /sys/fs/o2cb. The symlink will
+		be removed when new versions of ocfs2-tools which know to look
+		in /sys/fs/o2cb are sufficiently prevalent. Don't code new
+		software to look here, it should try /sys/fs/o2cb instead.
+		See Documentation/ABI/stable/o2cb for more information on usage.
+Users:		ocfs2-tools. It's sufficient to mail proposed changes to
+		ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/ABI/stable/o2cb b/Documentation/ABI/stable/o2cb
new file mode 100644
index 00000000000..5eb1545e0b8
--- /dev/null
+++ b/Documentation/ABI/stable/o2cb
@@ -0,0 +1,10 @@
+What:		/sys/fs/o2cb/ (was /sys/o2cb)
+Date:		Dec 2005
+KernelVersion:	2.6.16
+Contact:	ocfs2-devel@oss.oracle.com
+Description:	Ocfs2-tools looks at 'interface-revision' for versioning
+		information. Each logmask/ file controls a set of debug prints
+		and can be written into with the strings "allow", "deny", or
+		"off". Reading the file returns the current state.
+Users:		ocfs2-tools. It's sufficient to mail proposed changes to
+		ocfs2-devel@oss.oracle.com.
diff --git a/Documentation/ABI/testing/sysfs-ocfs2 b/Documentation/ABI/testing/sysfs-ocfs2
new file mode 100644
index 00000000000..b7cc516a8a8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-ocfs2
@@ -0,0 +1,89 @@
+What:		/sys/fs/ocfs2/
+Date:		April 2008
+Contact:	ocfs2-devel@oss.oracle.com
+Description:
+		The /sys/fs/ocfs2 directory contains knobs used by the
+		ocfs2-tools to interact with the filesystem.
+
+What:		/sys/fs/ocfs2/max_locking_protocol
+Date:		April 2008
+Contact:	ocfs2-devel@oss.oracle.com
+Description:
+		The /sys/fs/ocfs2/max_locking_protocol file displays version
+		of ocfs2 locking supported by the filesystem.  This version
+		covers how ocfs2 uses distributed locking between cluster
+		nodes.
+
+		The protocol version has a major and minor number.  Two
+		cluster nodes can interoperate if they have an identical
+		major number and an overlapping minor number - thus,
+		a node with version 1.10 can interoperate with a node
+		sporting version 1.8, as long as both use the 1.8 protocol.
+
+		Reading from this file returns a single line, the major
+		number and minor number joined by a period, eg "1.10".
+
+		This file is read-only.  The value is compiled into the
+		driver.
+
+What:		/sys/fs/ocfs2/loaded_cluster_plugins
+Date:		April 2008
+Contact:	ocfs2-devel@oss.oracle.com
+Description:
+		The /sys/fs/ocfs2/loaded_cluster_plugins file describes
+		the available plugins to support ocfs2 cluster operation.
+		A cluster plugin is required to use ocfs2 in a cluster.
+		There are currently two available plugins:
+
+		* 'o2cb' - The classic o2cb cluster stack that ocfs2 has
+			used since its inception.
+		* 'user' - A plugin supporting userspace cluster software
+			in conjunction with fs/dlm.
+
+		Reading from this file returns the names of all loaded
+		plugins, one per line.
+
+		This file is read-only.  Its contents may change as
+		plugins are loaded or removed.
+
+What:		/sys/fs/ocfs2/active_cluster_plugin
+Date:		April 2008
+Contact:	ocfs2-devel@oss.oracle.com
+Description:
+		The /sys/fs/ocfs2/active_cluster_plugin displays which
+		cluster plugin is currently in use by the filesystem.
+		The active plugin will appear in the loaded_cluster_plugins
+		file as well.  Only one plugin can be used at a time.
+
+		Reading from this file returns the name of the active plugin
+		on a single line.
+
+		This file is read-only.  Which plugin is active depends on
+		the cluster stack in use.  The contents may change
+		when all filesystems are unmounted and the cluster stack
+		is changed.
+
+What:		/sys/fs/ocfs2/cluster_stack
+Date:		April 2008
+Contact:	ocfs2-devel@oss.oracle.com
+Description:
+		The /sys/fs/ocfs2/cluster_stack file contains the name
+		of current ocfs2 cluster stack.  This value is set by
+		userspace tools when bringing the cluster stack online.
+
+		Cluster stack names are 4 characters in length.
+
+		When the 'o2cb' cluster stack is used, the 'o2cb' cluster
+		plugin is active.  All other cluster stacks use the 'user'
+		cluster plugin.
+
+		Reading from this file returns the name of the current
+		cluster stack on a single line.
+
+		Writing a new stack name to this file changes the current
+		cluster stack unless there are mounted ocfs2 filesystems.
+		If there are mounted filesystems, attempts to change the
+		stack return an error.
+
+Users:
+	ocfs2-tools <ocfs2-tools-devel@oss.oracle.com>
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index 164c89394cf..4b70622a8a9 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -318,3 +318,13 @@ Why:	Not used in-tree. The current out-of-tree users used it to
 	code / infrastructure should be in the kernel and not in some
 	out-of-tree driver.
 Who:	Thomas Gleixner <tglx@linutronix.de>
+
+---------------------------
+
+What:	/sys/o2cb symlink
+When:	January 2010
+Why:	/sys/fs/o2cb is the proper location for this information - /sys/o2cb
+	exists as a symlink for backwards compatibility for old versions of
+	ocfs2-tools. 2 years should be sufficient time to phase in new versions
+	which know to look in /sys/fs/o2cb.
+Who:	ocfs2-devel@oss.oracle.com
diff --git a/MAINTAINERS b/MAINTAINERS
index 3eceebb48c9..974ee8ddb12 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2952,6 +2952,7 @@ P:	Joel Becker
 M:	joel.becker@oracle.com
 L:	ocfs2-devel@oss.oracle.com
 W:	http://oss.oracle.com/projects/ocfs2/
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2.git
 S:	Supported
 
 OMNIKEY CARDMAN 4000 DRIVER
diff --git a/fs/Kconfig b/fs/Kconfig
index c509123bea4..028ae38ecc5 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -444,6 +444,32 @@ config OCFS2_FS
 	  For more information on OCFS2, see the file
 	  <file:Documentation/filesystems/ocfs2.txt>.
 
+config OCFS2_FS_O2CB
+	tristate "O2CB Kernelspace Clustering"
+	depends on OCFS2_FS
+	default y
+	help
+	  OCFS2 includes a simple kernelspace clustering package, the OCFS2
+	  Cluster Base.  It only requires a very small userspace component
+	  to configure it. This comes with the standard ocfs2-tools package.
+	  O2CB is limited to maintaining a cluster for OCFS2 file systems.
+	  It cannot manage any other cluster applications.
+
+	  It is always safe to say Y here, as the clustering method is
+	  run-time selectable.
+
+config OCFS2_FS_USERSPACE_CLUSTER
+	tristate "OCFS2 Userspace Clustering"
+	depends on OCFS2_FS && DLM
+	default y
+	help
+	  This option will allow OCFS2 to use userspace clustering services
+	  in conjunction with the DLM in fs/dlm.  If you are using a
+	  userspace cluster manager, say Y here.
+
+	  It is safe to say Y, as the clustering method is run-time
+	  selectable.
+
 config OCFS2_DEBUG_MASKLOG
 	bool "OCFS2 logging support"
 	depends on OCFS2_FS
diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index 4d4ce48bb42..f6956de56fd 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -2,7 +2,12 @@ EXTRA_CFLAGS += -Ifs/ocfs2
 
 EXTRA_CFLAGS += -DCATCH_BH_JBD_RACES
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2.o
+obj-$(CONFIG_OCFS2_FS) += 	\
+	ocfs2.o			\
+	ocfs2_stackglue.o
+
+obj-$(CONFIG_OCFS2_FS_O2CB) += ocfs2_stack_o2cb.o
+obj-$(CONFIG_OCFS2_FS_USERSPACE_CLUSTER) += ocfs2_stack_user.o
 
 ocfs2-objs := \
 	alloc.o 		\
@@ -31,5 +36,10 @@ ocfs2-objs := \
 	uptodate.o		\
 	ver.o
 
+ocfs2_stackglue-objs := stackglue.o
+ocfs2_stack_o2cb-objs := stack_o2cb.o
+ocfs2_stack_user-objs := stack_user.o
+
+# cluster/ is always needed when OCFS2_FS for masklog support
 obj-$(CONFIG_OCFS2_FS) += cluster/
-obj-$(CONFIG_OCFS2_FS) += dlm/
+obj-$(CONFIG_OCFS2_FS_O2CB) += dlm/
diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 447206eb5c2..41f84c92094 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -1029,8 +1029,7 @@ static void ocfs2_rotate_leaf(struct ocfs2_extent_list *el,
 	BUG_ON(!next_free);
 
 	/* The tree code before us didn't allow enough room in the leaf. */
-	if (el->l_next_free_rec == el->l_count && !has_empty)
-		BUG();
+	BUG_ON(el->l_next_free_rec == el->l_count && !has_empty);
 
 	/*
 	 * The easiest way to approach this is to just remove the
@@ -1450,6 +1449,8 @@ static void ocfs2_adjust_root_records(struct ocfs2_extent_list *root_el,
  *   - When our insert into the right path leaf is at the leftmost edge
  *     and requires an update of the path immediately to it's left. This
  *     can occur at the end of some types of rotation and appending inserts.
+ *   - When we've adjusted the last extent record in the left path leaf and the
+ *     1st extent record in the right path leaf during cross extent block merge.
  */
 static void ocfs2_complete_edge_insert(struct inode *inode, handle_t *handle,
 				       struct ocfs2_path *left_path,
@@ -2712,24 +2713,147 @@ static void ocfs2_cleanup_merge(struct ocfs2_extent_list *el,
 	}
 }
 
+static int ocfs2_get_right_path(struct inode *inode,
+				struct ocfs2_path *left_path,
+				struct ocfs2_path **ret_right_path)
+{
+	int ret;
+	u32 right_cpos;
+	struct ocfs2_path *right_path = NULL;
+	struct ocfs2_extent_list *left_el;
+
+	*ret_right_path = NULL;
+
+	/* This function shouldn't be called for non-trees. */
+	BUG_ON(left_path->p_tree_depth == 0);
+
+	left_el = path_leaf_el(left_path);
+	BUG_ON(left_el->l_next_free_rec != left_el->l_count);
+
+	ret = ocfs2_find_cpos_for_right_leaf(inode->i_sb, left_path,
+					     &right_cpos);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	/* This function shouldn't be called for the rightmost leaf. */
+	BUG_ON(right_cpos == 0);
+
+	right_path = ocfs2_new_path(path_root_bh(left_path),
+				    path_root_el(left_path));
+	if (!right_path) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_find_path(inode, right_path, right_cpos);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	*ret_right_path = right_path;
+out:
+	if (ret)
+		ocfs2_free_path(right_path);
+	return ret;
+}
+
 /*
  * Remove split_rec clusters from the record at index and merge them
- * onto the beginning of the record at index + 1.
+ * onto the beginning of the record "next" to it.
+ * For index < l_count - 1, the next means the extent rec at index + 1.
+ * For index == l_count - 1, the "next" means the 1st extent rec of the
+ * next extent block.
  */
-static int ocfs2_merge_rec_right(struct inode *inode, struct buffer_head *bh,
-				handle_t *handle,
-				struct ocfs2_extent_rec *split_rec,
-				struct ocfs2_extent_list *el, int index)
+static int ocfs2_merge_rec_right(struct inode *inode,
+				 struct ocfs2_path *left_path,
+				 handle_t *handle,
+				 struct ocfs2_extent_rec *split_rec,
+				 int index)
 {
-	int ret;
+	int ret, next_free, i;
 	unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
 	struct ocfs2_extent_rec *left_rec;
 	struct ocfs2_extent_rec *right_rec;
+	struct ocfs2_extent_list *right_el;
+	struct ocfs2_path *right_path = NULL;
+	int subtree_index = 0;
+	struct ocfs2_extent_list *el = path_leaf_el(left_path);
+	struct buffer_head *bh = path_leaf_bh(left_path);
+	struct buffer_head *root_bh = NULL;
 
 	BUG_ON(index >= le16_to_cpu(el->l_next_free_rec));
-
 	left_rec = &el->l_recs[index];
-	right_rec = &el->l_recs[index + 1];
+
+	if (index == le16_to_cpu(el->l_next_free_rec - 1) &&
+	    le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count)) {
+		/* we meet with a cross extent block merge. */
+		ret = ocfs2_get_right_path(inode, left_path, &right_path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		right_el = path_leaf_el(right_path);
+		next_free = le16_to_cpu(right_el->l_next_free_rec);
+		BUG_ON(next_free <= 0);
+		right_rec = &right_el->l_recs[0];
+		if (ocfs2_is_empty_extent(right_rec)) {
+			BUG_ON(le16_to_cpu(next_free) <= 1);
+			right_rec = &right_el->l_recs[1];
+		}
+
+		BUG_ON(le32_to_cpu(left_rec->e_cpos) +
+		       le16_to_cpu(left_rec->e_leaf_clusters) !=
+		       le32_to_cpu(right_rec->e_cpos));
+
+		subtree_index = ocfs2_find_subtree_root(inode,
+							left_path, right_path);
+
+		ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
+						      handle->h_buffer_credits,
+						      right_path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		root_bh = left_path->p_node[subtree_index].bh;
+		BUG_ON(root_bh != right_path->p_node[subtree_index].bh);
+
+		ret = ocfs2_journal_access(handle, inode, root_bh,
+					   OCFS2_JOURNAL_ACCESS_WRITE);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		for (i = subtree_index + 1;
+		     i < path_num_items(right_path); i++) {
+			ret = ocfs2_journal_access(handle, inode,
+						   right_path->p_node[i].bh,
+						   OCFS2_JOURNAL_ACCESS_WRITE);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+
+			ret = ocfs2_journal_access(handle, inode,
+						   left_path->p_node[i].bh,
+						   OCFS2_JOURNAL_ACCESS_WRITE);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+		}
+
+	} else {
+		BUG_ON(index == le16_to_cpu(el->l_next_free_rec) - 1);
+		right_rec = &el->l_recs[index + 1];
+	}
 
 	ret = ocfs2_journal_access(handle, inode, bh,
 				   OCFS2_JOURNAL_ACCESS_WRITE);
@@ -2751,30 +2875,156 @@ static int ocfs2_merge_rec_right(struct inode *inode, struct buffer_head *bh,
 	if (ret)
 		mlog_errno(ret);
 
+	if (right_path) {
+		ret = ocfs2_journal_dirty(handle, path_leaf_bh(right_path));
+		if (ret)
+			mlog_errno(ret);
+
+		ocfs2_complete_edge_insert(inode, handle, left_path,
+					   right_path, subtree_index);
+	}
+out:
+	if (right_path)
+		ocfs2_free_path(right_path);
+	return ret;
+}
+
+static int ocfs2_get_left_path(struct inode *inode,
+			       struct ocfs2_path *right_path,
+			       struct ocfs2_path **ret_left_path)
+{
+	int ret;
+	u32 left_cpos;
+	struct ocfs2_path *left_path = NULL;
+
+	*ret_left_path = NULL;
+
+	/* This function shouldn't be called for non-trees. */
+	BUG_ON(right_path->p_tree_depth == 0);
+
+	ret = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
+					    right_path, &left_cpos);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	/* This function shouldn't be called for the leftmost leaf. */
+	BUG_ON(left_cpos == 0);
+
+	left_path = ocfs2_new_path(path_root_bh(right_path),
+				   path_root_el(right_path));
+	if (!left_path) {
+		ret = -ENOMEM;
+		mlog_errno(ret);
+		goto out;
+	}
+
+	ret = ocfs2_find_path(inode, left_path, left_cpos);
+	if (ret) {
+		mlog_errno(ret);
+		goto out;
+	}
+
+	*ret_left_path = left_path;
 out:
+	if (ret)
+		ocfs2_free_path(left_path);
 	return ret;
 }
 
 /*
  * Remove split_rec clusters from the record at index and merge them
- * onto the tail of the record at index - 1.
+ * onto the tail of the record "before" it.
+ * For index > 0, the "before" means the extent rec at index - 1.
+ *
+ * For index == 0, the "before" means the last record of the previous
+ * extent block. And there is also a situation that we may need to
+ * remove the rightmost leaf extent block in the right_path and change
+ * the right path to indicate the new rightmost path.
  */
-static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
+static int ocfs2_merge_rec_left(struct inode *inode,
+				struct ocfs2_path *right_path,
 				handle_t *handle,
 				struct ocfs2_extent_rec *split_rec,
-				struct ocfs2_extent_list *el, int index)
+				struct ocfs2_cached_dealloc_ctxt *dealloc,
+				int index)
 {
-	int ret, has_empty_extent = 0;
+	int ret, i, subtree_index = 0, has_empty_extent = 0;
 	unsigned int split_clusters = le16_to_cpu(split_rec->e_leaf_clusters);
 	struct ocfs2_extent_rec *left_rec;
 	struct ocfs2_extent_rec *right_rec;
+	struct ocfs2_extent_list *el = path_leaf_el(right_path);
+	struct buffer_head *bh = path_leaf_bh(right_path);
+	struct buffer_head *root_bh = NULL;
+	struct ocfs2_path *left_path = NULL;
+	struct ocfs2_extent_list *left_el;
 
-	BUG_ON(index <= 0);
+	BUG_ON(index < 0);
 
-	left_rec = &el->l_recs[index - 1];
 	right_rec = &el->l_recs[index];
-	if (ocfs2_is_empty_extent(&el->l_recs[0]))
-		has_empty_extent = 1;
+	if (index == 0) {
+		/* we meet with a cross extent block merge. */
+		ret = ocfs2_get_left_path(inode, right_path, &left_path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		left_el = path_leaf_el(left_path);
+		BUG_ON(le16_to_cpu(left_el->l_next_free_rec) !=
+		       le16_to_cpu(left_el->l_count));
+
+		left_rec = &left_el->l_recs[
+				le16_to_cpu(left_el->l_next_free_rec) - 1];
+		BUG_ON(le32_to_cpu(left_rec->e_cpos) +
+		       le16_to_cpu(left_rec->e_leaf_clusters) !=
+		       le32_to_cpu(split_rec->e_cpos));
+
+		subtree_index = ocfs2_find_subtree_root(inode,
+							left_path, right_path);
+
+		ret = ocfs2_extend_rotate_transaction(handle, subtree_index,
+						      handle->h_buffer_credits,
+						      left_path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		root_bh = left_path->p_node[subtree_index].bh;
+		BUG_ON(root_bh != right_path->p_node[subtree_index].bh);
+
+		ret = ocfs2_journal_access(handle, inode, root_bh,
+					   OCFS2_JOURNAL_ACCESS_WRITE);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
+		for (i = subtree_index + 1;
+		     i < path_num_items(right_path); i++) {
+			ret = ocfs2_journal_access(handle, inode,
+						   right_path->p_node[i].bh,
+						   OCFS2_JOURNAL_ACCESS_WRITE);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+
+			ret = ocfs2_journal_access(handle, inode,
+						   left_path->p_node[i].bh,
+						   OCFS2_JOURNAL_ACCESS_WRITE);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+		}
+	} else {
+		left_rec = &el->l_recs[index - 1];
+		if (ocfs2_is_empty_extent(&el->l_recs[0]))
+			has_empty_extent = 1;
+	}
 
 	ret = ocfs2_journal_access(handle, inode, bh,
 				   OCFS2_JOURNAL_ACCESS_WRITE);
@@ -2790,9 +3040,8 @@ static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
 		*left_rec = *split_rec;
 
 		has_empty_extent = 0;
-	} else {
+	} else
 		le16_add_cpu(&left_rec->e_leaf_clusters, split_clusters);
-	}
 
 	le32_add_cpu(&right_rec->e_cpos, split_clusters);
 	le64_add_cpu(&right_rec->e_blkno,
@@ -2805,13 +3054,44 @@ static int ocfs2_merge_rec_left(struct inode *inode, struct buffer_head *bh,
 	if (ret)
 		mlog_errno(ret);
 
+	if (left_path) {
+		ret = ocfs2_journal_dirty(handle, path_leaf_bh(left_path));
+		if (ret)
+			mlog_errno(ret);
+
+		/*
+		 * In the situation that the right_rec is empty and the extent
+		 * block is empty also,  ocfs2_complete_edge_insert can't handle
+		 * it and we need to delete the right extent block.
+		 */
+		if (le16_to_cpu(right_rec->e_leaf_clusters) == 0 &&
+		    le16_to_cpu(el->l_next_free_rec) == 1) {
+
+			ret = ocfs2_remove_rightmost_path(inode, handle,
+							  right_path, dealloc);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
+
+			/* Now the rightmost extent block has been deleted.
+			 * So we use the new rightmost path.
+			 */
+			ocfs2_mv_path(right_path, left_path);
+			left_path = NULL;
+		} else
+			ocfs2_complete_edge_insert(inode, handle, left_path,
+						   right_path, subtree_index);
+	}
 out:
+	if (left_path)
+		ocfs2_free_path(left_path);
 	return ret;
 }
 
 static int ocfs2_try_to_merge_extent(struct inode *inode,
 				     handle_t *handle,
-				     struct ocfs2_path *left_path,
+				     struct ocfs2_path *path,
 				     int split_index,
 				     struct ocfs2_extent_rec *split_rec,
 				     struct ocfs2_cached_dealloc_ctxt *dealloc,
@@ -2819,7 +3099,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 
 {
 	int ret = 0;
-	struct ocfs2_extent_list *el = path_leaf_el(left_path);
+	struct ocfs2_extent_list *el = path_leaf_el(path);
 	struct ocfs2_extent_rec *rec = &el->l_recs[split_index];
 
 	BUG_ON(ctxt->c_contig_type == CONTIG_NONE);
@@ -2832,7 +3112,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 		 * extents - having more than one in a leaf is
 		 * illegal.
 		 */
-		ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+		ret = ocfs2_rotate_tree_left(inode, handle, path,
 					     dealloc);
 		if (ret) {
 			mlog_errno(ret);
@@ -2847,7 +3127,6 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 		 * Left-right contig implies this.
 		 */
 		BUG_ON(!ctxt->c_split_covers_rec);
-		BUG_ON(split_index == 0);
 
 		/*
 		 * Since the leftright insert always covers the entire
@@ -2858,9 +3137,14 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 		 * Since the adding of an empty extent shifts
 		 * everything back to the right, there's no need to
 		 * update split_index here.
+		 *
+		 * When the split_index is zero, we need to merge it to the
+		 * prevoius extent block. It is more efficient and easier
+		 * if we do merge_right first and merge_left later.
 		 */
-		ret = ocfs2_merge_rec_left(inode, path_leaf_bh(left_path),
-					   handle, split_rec, el, split_index);
+		ret = ocfs2_merge_rec_right(inode, path,
+					    handle, split_rec,
+					    split_index);
 		if (ret) {
 			mlog_errno(ret);
 			goto out;
@@ -2871,32 +3155,30 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 		 */
 		BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
 
-		/*
-		 * The left merge left us with an empty extent, remove
-		 * it.
-		 */
-		ret = ocfs2_rotate_tree_left(inode, handle, left_path, dealloc);
+		/* The merge left us with an empty extent, remove it. */
+		ret = ocfs2_rotate_tree_left(inode, handle, path, dealloc);
 		if (ret) {
 			mlog_errno(ret);
 			goto out;
 		}
-		split_index--;
+
 		rec = &el->l_recs[split_index];
 
 		/*
 		 * Note that we don't pass split_rec here on purpose -
-		 * we've merged it into the left side.
+		 * we've merged it into the rec already.
 		 */
-		ret = ocfs2_merge_rec_right(inode, path_leaf_bh(left_path),
-					    handle, rec, el, split_index);
+		ret = ocfs2_merge_rec_left(inode, path,
+					   handle, rec,
+					   dealloc,
+					   split_index);
+
 		if (ret) {
 			mlog_errno(ret);
 			goto out;
 		}
 
-		BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
-
-		ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+		ret = ocfs2_rotate_tree_left(inode, handle, path,
 					     dealloc);
 		/*
 		 * Error from this last rotate is not critical, so
@@ -2915,8 +3197,9 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 		 */
 		if (ctxt->c_contig_type == CONTIG_RIGHT) {
 			ret = ocfs2_merge_rec_left(inode,
-						   path_leaf_bh(left_path),
-						   handle, split_rec, el,
+						   path,
+						   handle, split_rec,
+						   dealloc,
 						   split_index);
 			if (ret) {
 				mlog_errno(ret);
@@ -2924,8 +3207,8 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 			}
 		} else {
 			ret = ocfs2_merge_rec_right(inode,
-						    path_leaf_bh(left_path),
-						    handle, split_rec, el,
+						    path,
+						    handle, split_rec,
 						    split_index);
 			if (ret) {
 				mlog_errno(ret);
@@ -2938,7 +3221,7 @@ static int ocfs2_try_to_merge_extent(struct inode *inode,
 			 * The merge may have left an empty extent in
 			 * our leaf. Try to rotate it away.
 			 */
-			ret = ocfs2_rotate_tree_left(inode, handle, left_path,
+			ret = ocfs2_rotate_tree_left(inode, handle, path,
 						     dealloc);
 			if (ret)
 				mlog_errno(ret);
@@ -3498,20 +3781,57 @@ out:
 }
 
 static enum ocfs2_contig_type
-ocfs2_figure_merge_contig_type(struct inode *inode,
+ocfs2_figure_merge_contig_type(struct inode *inode, struct ocfs2_path *path,
 			       struct ocfs2_extent_list *el, int index,
 			       struct ocfs2_extent_rec *split_rec)
 {
-	struct ocfs2_extent_rec *rec;
+	int status;
 	enum ocfs2_contig_type ret = CONTIG_NONE;
+	u32 left_cpos, right_cpos;
+	struct ocfs2_extent_rec *rec = NULL;
+	struct ocfs2_extent_list *new_el;
+	struct ocfs2_path *left_path = NULL, *right_path = NULL;
+	struct buffer_head *bh;
+	struct ocfs2_extent_block *eb;
+
+	if (index > 0) {
+		rec = &el->l_recs[index - 1];
+	} else if (path->p_tree_depth > 0) {
+		status = ocfs2_find_cpos_for_left_leaf(inode->i_sb,
+						       path, &left_cpos);
+		if (status)
+			goto out;
+
+		if (left_cpos != 0) {
+			left_path = ocfs2_new_path(path_root_bh(path),
+						   path_root_el(path));
+			if (!left_path)
+				goto out;
+
+			status = ocfs2_find_path(inode, left_path, left_cpos);
+			if (status)
+				goto out;
+
+			new_el = path_leaf_el(left_path);
+
+			if (le16_to_cpu(new_el->l_next_free_rec) !=
+			    le16_to_cpu(new_el->l_count)) {
+				bh = path_leaf_bh(left_path);
+				eb = (struct ocfs2_extent_block *)bh->b_data;
+				OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb,
+								 eb);
+				goto out;
+			}
+			rec = &new_el->l_recs[
+				le16_to_cpu(new_el->l_next_free_rec) - 1];
+		}
+	}
 
 	/*
 	 * We're careful to check for an empty extent record here -
 	 * the merge code will know what to do if it sees one.
 	 */
-
-	if (index > 0) {
-		rec = &el->l_recs[index - 1];
+	if (rec) {
 		if (index == 1 && ocfs2_is_empty_extent(rec)) {
 			if (split_rec->e_cpos == el->l_recs[index].e_cpos)
 				ret = CONTIG_RIGHT;
@@ -3520,10 +3840,45 @@ ocfs2_figure_merge_contig_type(struct inode *inode,
 		}
 	}
 
-	if (index < (le16_to_cpu(el->l_next_free_rec) - 1)) {
+	rec = NULL;
+	if (index < (le16_to_cpu(el->l_next_free_rec) - 1))
+		rec = &el->l_recs[index + 1];
+	else if (le16_to_cpu(el->l_next_free_rec) == le16_to_cpu(el->l_count) &&
+		 path->p_tree_depth > 0) {
+		status = ocfs2_find_cpos_for_right_leaf(inode->i_sb,
+							path, &right_cpos);
+		if (status)
+			goto out;
+
+		if (right_cpos == 0)
+			goto out;
+
+		right_path = ocfs2_new_path(path_root_bh(path),
+					    path_root_el(path));
+		if (!right_path)
+			goto out;
+
+		status = ocfs2_find_path(inode, right_path, right_cpos);
+		if (status)
+			goto out;
+
+		new_el = path_leaf_el(right_path);
+		rec = &new_el->l_recs[0];
+		if (ocfs2_is_empty_extent(rec)) {
+			if (le16_to_cpu(new_el->l_next_free_rec) <= 1) {
+				bh = path_leaf_bh(right_path);
+				eb = (struct ocfs2_extent_block *)bh->b_data;
+				OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb,
+								 eb);
+				goto out;
+			}
+			rec = &new_el->l_recs[1];
+		}
+	}
+
+	if (rec) {
 		enum ocfs2_contig_type contig_type;
 
-		rec = &el->l_recs[index + 1];
 		contig_type = ocfs2_extent_contig(inode, rec, split_rec);
 
 		if (contig_type == CONTIG_LEFT && ret == CONTIG_RIGHT)
@@ -3532,6 +3887,12 @@ ocfs2_figure_merge_contig_type(struct inode *inode,
 			ret = contig_type;
 	}
 
+out:
+	if (left_path)
+		ocfs2_free_path(left_path);
+	if (right_path)
+		ocfs2_free_path(right_path);
+
 	return ret;
 }
 
@@ -3994,7 +4355,7 @@ static int __ocfs2_mark_extent_written(struct inode *inode,
 		goto out;
 	}
 
-	ctxt.c_contig_type = ocfs2_figure_merge_contig_type(inode, el,
+	ctxt.c_contig_type = ocfs2_figure_merge_contig_type(inode, path, el,
 							    split_index,
 							    split_rec);
 
@@ -4788,6 +5149,8 @@ static void ocfs2_truncate_log_worker(struct work_struct *work)
 	status = ocfs2_flush_truncate_log(osb);
 	if (status < 0)
 		mlog_errno(status);
+	else
+		ocfs2_init_inode_steal_slot(osb);
 
 	mlog_exit(status);
 }
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 90383ed6100..17964c0505a 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -467,11 +467,11 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
 							 unsigned to)
 {
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
-	handle_t *handle = NULL;
+	handle_t *handle;
 	int ret = 0;
 
 	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
-	if (!handle) {
+	if (IS_ERR(handle)) {
 		ret = -ENOMEM;
 		mlog_errno(ret);
 		goto out;
@@ -487,7 +487,7 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
 	}
 out:
 	if (ret) {
-		if (handle)
+		if (!IS_ERR(handle))
 			ocfs2_commit_trans(osb, handle);
 		handle = ERR_PTR(ret);
 	}
diff --git a/fs/ocfs2/cluster/Makefile b/fs/ocfs2/cluster/Makefile
index cdd162f1365..bc8c5e7d860 100644
--- a/fs/ocfs2/cluster/Makefile
+++ b/fs/ocfs2/cluster/Makefile
@@ -1,4 +1,4 @@
 obj-$(CONFIG_OCFS2_FS) += ocfs2_nodemanager.o
 
 ocfs2_nodemanager-objs := heartbeat.o masklog.o sys.o nodemanager.o \
-	quorum.o tcp.o ver.o
+	quorum.o tcp.o netdebug.o ver.o
diff --git a/fs/ocfs2/cluster/netdebug.c b/fs/ocfs2/cluster/netdebug.c
new file mode 100644
index 00000000000..7bf3c0ea7bd
--- /dev/null
+++ b/fs/ocfs2/cluster/netdebug.c
@@ -0,0 +1,441 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * netdebug.c
+ *
+ * debug functionality for o2net
+ *
+ * Copyright (C) 2005, 2008 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.
+ *
+ */
+
+#ifdef CONFIG_DEBUG_FS
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/kref.h>
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+
+#include <linux/uaccess.h>
+
+#include "tcp.h"
+#include "nodemanager.h"
+#define MLOG_MASK_PREFIX ML_TCP
+#include "masklog.h"
+
+#include "tcp_internal.h"
+
+#define O2NET_DEBUG_DIR		"o2net"
+#define SC_DEBUG_NAME		"sock_containers"
+#define NST_DEBUG_NAME		"send_tracking"
+
+static struct dentry *o2net_dentry;
+static struct dentry *sc_dentry;
+static struct dentry *nst_dentry;
+
+static DEFINE_SPINLOCK(o2net_debug_lock);
+
+static LIST_HEAD(sock_containers);
+static LIST_HEAD(send_tracking);
+
+void o2net_debug_add_nst(struct o2net_send_tracking *nst)
+{
+	spin_lock(&o2net_debug_lock);
+	list_add(&nst->st_net_debug_item, &send_tracking);
+	spin_unlock(&o2net_debug_lock);
+}
+
+void o2net_debug_del_nst(struct o2net_send_tracking *nst)
+{
+	spin_lock(&o2net_debug_lock);
+	if (!list_empty(&nst->st_net_debug_item))
+		list_del_init(&nst->st_net_debug_item);
+	spin_unlock(&o2net_debug_lock);
+}
+
+static struct o2net_send_tracking
+			*next_nst(struct o2net_send_tracking *nst_start)
+{
+	struct o2net_send_tracking *nst, *ret = NULL;
+
+	assert_spin_locked(&o2net_debug_lock);
+
+	list_for_each_entry(nst, &nst_start->st_net_debug_item,
+			    st_net_debug_item) {
+		/* discover the head of the list */
+		if (&nst->st_net_debug_item == &send_tracking)
+			break;
+
+		/* use st_task to detect real nsts in the list */
+		if (nst->st_task != NULL) {
+			ret = nst;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void *nst_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	nst = next_nst(dummy_nst);
+	spin_unlock(&o2net_debug_lock);
+
+	return nst;
+}
+
+static void *nst_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	nst = next_nst(dummy_nst);
+	list_del_init(&dummy_nst->st_net_debug_item);
+	if (nst)
+		list_add(&dummy_nst->st_net_debug_item,
+			 &nst->st_net_debug_item);
+	spin_unlock(&o2net_debug_lock);
+
+	return nst; /* unused, just needs to be null when done */
+}
+
+static int nst_seq_show(struct seq_file *seq, void *v)
+{
+	struct o2net_send_tracking *nst, *dummy_nst = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	nst = next_nst(dummy_nst);
+
+	if (nst != NULL) {
+		/* get_task_comm isn't exported.  oh well. */
+		seq_printf(seq, "%p:\n"
+			   "  pid:          %lu\n"
+			   "  tgid:         %lu\n"
+			   "  process name: %s\n"
+			   "  node:         %u\n"
+			   "  sc:           %p\n"
+			   "  message id:   %d\n"
+			   "  message type: %u\n"
+			   "  message key:  0x%08x\n"
+			   "  sock acquiry: %lu.%lu\n"
+			   "  send start:   %lu.%lu\n"
+			   "  wait start:   %lu.%lu\n",
+			   nst, (unsigned long)nst->st_task->pid,
+			   (unsigned long)nst->st_task->tgid,
+			   nst->st_task->comm, nst->st_node,
+			   nst->st_sc, nst->st_id, nst->st_msg_type,
+			   nst->st_msg_key,
+			   nst->st_sock_time.tv_sec, nst->st_sock_time.tv_usec,
+			   nst->st_send_time.tv_sec, nst->st_send_time.tv_usec,
+			   nst->st_status_time.tv_sec,
+			   nst->st_status_time.tv_usec);
+	}
+
+	spin_unlock(&o2net_debug_lock);
+
+	return 0;
+}
+
+static void nst_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations nst_seq_ops = {
+	.start = nst_seq_start,
+	.next = nst_seq_next,
+	.stop = nst_seq_stop,
+	.show = nst_seq_show,
+};
+
+static int nst_fop_open(struct inode *inode, struct file *file)
+{
+	struct o2net_send_tracking *dummy_nst;
+	struct seq_file *seq;
+	int ret;
+
+	dummy_nst = kmalloc(sizeof(struct o2net_send_tracking), GFP_KERNEL);
+	if (dummy_nst == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	dummy_nst->st_task = NULL;
+
+	ret = seq_open(file, &nst_seq_ops);
+	if (ret)
+		goto out;
+
+	seq = file->private_data;
+	seq->private = dummy_nst;
+	o2net_debug_add_nst(dummy_nst);
+
+	dummy_nst = NULL;
+
+out:
+	kfree(dummy_nst);
+	return ret;
+}
+
+static int nst_fop_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+	struct o2net_send_tracking *dummy_nst = seq->private;
+
+	o2net_debug_del_nst(dummy_nst);
+	return seq_release_private(inode, file);
+}
+
+static struct file_operations nst_seq_fops = {
+	.open = nst_fop_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = nst_fop_release,
+};
+
+void o2net_debug_add_sc(struct o2net_sock_container *sc)
+{
+	spin_lock(&o2net_debug_lock);
+	list_add(&sc->sc_net_debug_item, &sock_containers);
+	spin_unlock(&o2net_debug_lock);
+}
+
+void o2net_debug_del_sc(struct o2net_sock_container *sc)
+{
+	spin_lock(&o2net_debug_lock);
+	list_del_init(&sc->sc_net_debug_item);
+	spin_unlock(&o2net_debug_lock);
+}
+
+static struct o2net_sock_container
+			*next_sc(struct o2net_sock_container *sc_start)
+{
+	struct o2net_sock_container *sc, *ret = NULL;
+
+	assert_spin_locked(&o2net_debug_lock);
+
+	list_for_each_entry(sc, &sc_start->sc_net_debug_item,
+			    sc_net_debug_item) {
+		/* discover the head of the list miscast as a sc */
+		if (&sc->sc_net_debug_item == &sock_containers)
+			break;
+
+		/* use sc_page to detect real scs in the list */
+		if (sc->sc_page != NULL) {
+			ret = sc;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static void *sc_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	sc = next_sc(dummy_sc);
+	spin_unlock(&o2net_debug_lock);
+
+	return sc;
+}
+
+static void *sc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	sc = next_sc(dummy_sc);
+	list_del_init(&dummy_sc->sc_net_debug_item);
+	if (sc)
+		list_add(&dummy_sc->sc_net_debug_item, &sc->sc_net_debug_item);
+	spin_unlock(&o2net_debug_lock);
+
+	return sc; /* unused, just needs to be null when done */
+}
+
+#define TV_SEC_USEC(TV) TV.tv_sec, TV.tv_usec
+
+static int sc_seq_show(struct seq_file *seq, void *v)
+{
+	struct o2net_sock_container *sc, *dummy_sc = seq->private;
+
+	spin_lock(&o2net_debug_lock);
+	sc = next_sc(dummy_sc);
+
+	if (sc != NULL) {
+		struct inet_sock *inet = NULL;
+
+		__be32 saddr = 0, daddr = 0;
+		__be16 sport = 0, dport = 0;
+
+		if (sc->sc_sock) {
+			inet = inet_sk(sc->sc_sock->sk);
+			/* the stack's structs aren't sparse endian clean */
+			saddr = (__force __be32)inet->saddr;
+			daddr = (__force __be32)inet->daddr;
+			sport = (__force __be16)inet->sport;
+			dport = (__force __be16)inet->dport;
+		}
+
+		/* XXX sigh, inet-> doesn't have sparse annotation so any
+		 * use of it here generates a warning with -Wbitwise */
+		seq_printf(seq, "%p:\n"
+			   "  krefs:           %d\n"
+			   "  sock:            %u.%u.%u.%u:%u -> "
+					      "%u.%u.%u.%u:%u\n"
+			   "  remote node:     %s\n"
+			   "  page off:        %zu\n"
+			   "  handshake ok:    %u\n"
+			   "  timer:           %lu.%lu\n"
+			   "  data ready:      %lu.%lu\n"
+			   "  advance start:   %lu.%lu\n"
+			   "  advance stop:    %lu.%lu\n"
+			   "  func start:      %lu.%lu\n"
+			   "  func stop:       %lu.%lu\n"
+			   "  func key:        %u\n"
+			   "  func type:       %u\n",
+			   sc,
+			   atomic_read(&sc->sc_kref.refcount),
+			   NIPQUAD(saddr), inet ? ntohs(sport) : 0,
+			   NIPQUAD(daddr), inet ? ntohs(dport) : 0,
+			   sc->sc_node->nd_name,
+			   sc->sc_page_off,
+			   sc->sc_handshake_ok,
+			   TV_SEC_USEC(sc->sc_tv_timer),
+			   TV_SEC_USEC(sc->sc_tv_data_ready),
+			   TV_SEC_USEC(sc->sc_tv_advance_start),
+			   TV_SEC_USEC(sc->sc_tv_advance_stop),
+			   TV_SEC_USEC(sc->sc_tv_func_start),
+			   TV_SEC_USEC(sc->sc_tv_func_stop),
+			   sc->sc_msg_key,
+			   sc->sc_msg_type);
+	}
+
+
+	spin_unlock(&o2net_debug_lock);
+
+	return 0;
+}
+
+static void sc_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static struct seq_operations sc_seq_ops = {
+	.start = sc_seq_start,
+	.next = sc_seq_next,
+	.stop = sc_seq_stop,
+	.show = sc_seq_show,
+};
+
+static int sc_fop_open(struct inode *inode, struct file *file)
+{
+	struct o2net_sock_container *dummy_sc;
+	struct seq_file *seq;
+	int ret;
+
+	dummy_sc = kmalloc(sizeof(struct o2net_sock_container), GFP_KERNEL);
+	if (dummy_sc == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	dummy_sc->sc_page = NULL;
+
+	ret = seq_open(file, &sc_seq_ops);
+	if (ret)
+		goto out;
+
+	seq = file->private_data;
+	seq->private = dummy_sc;
+	o2net_debug_add_sc(dummy_sc);
+
+	dummy_sc = NULL;
+
+out:
+	kfree(dummy_sc);
+	return ret;
+}
+
+static int sc_fop_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = file->private_data;
+	struct o2net_sock_container *dummy_sc = seq->private;
+
+	o2net_debug_del_sc(dummy_sc);
+	return seq_release_private(inode, file);
+}
+
+static struct file_operations sc_seq_fops = {
+	.open = sc_fop_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = sc_fop_release,
+};
+
+int o2net_debugfs_init(void)
+{
+	o2net_dentry = debugfs_create_dir(O2NET_DEBUG_DIR, NULL);
+	if (!o2net_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	nst_dentry = debugfs_create_file(NST_DEBUG_NAME, S_IFREG|S_IRUSR,
+					 o2net_dentry, NULL,
+					 &nst_seq_fops);
+	if (!nst_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	sc_dentry = debugfs_create_file(SC_DEBUG_NAME, S_IFREG|S_IRUSR,
+					o2net_dentry, NULL,
+					&sc_seq_fops);
+	if (!sc_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	return 0;
+bail:
+	if (sc_dentry)
+		debugfs_remove(sc_dentry);
+	if (nst_dentry)
+		debugfs_remove(nst_dentry);
+	if (o2net_dentry)
+		debugfs_remove(o2net_dentry);
+	return -ENOMEM;
+}
+
+void o2net_debugfs_exit(void)
+{
+	if (sc_dentry)
+		debugfs_remove(sc_dentry);
+	if (nst_dentry)
+		debugfs_remove(nst_dentry);
+	if (o2net_dentry)
+		debugfs_remove(o2net_dentry);
+}
+
+#endif	/* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c
index 709fba25bf7..cf9401e8cd0 100644
--- a/fs/ocfs2/cluster/nodemanager.c
+++ b/fs/ocfs2/cluster/nodemanager.c
@@ -959,7 +959,10 @@ static int __init init_o2nm(void)
 	cluster_print_version();
 
 	o2hb_init();
-	o2net_init();
+
+	ret = o2net_init();
+	if (ret)
+		goto out;
 
 	ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
 	if (!ocfs2_table_header) {
diff --git a/fs/ocfs2/cluster/sys.c b/fs/ocfs2/cluster/sys.c
index 0c095ce7723..98429fd6849 100644
--- a/fs/ocfs2/cluster/sys.c
+++ b/fs/ocfs2/cluster/sys.c
@@ -57,6 +57,7 @@ static struct kset *o2cb_kset;
 void o2cb_sys_shutdown(void)
 {
 	mlog_sys_shutdown();
+	sysfs_remove_link(NULL, "o2cb");
 	kset_unregister(o2cb_kset);
 }
 
@@ -68,6 +69,14 @@ int o2cb_sys_init(void)
 	if (!o2cb_kset)
 		return -ENOMEM;
 
+	/*
+	 * Create this symlink for backwards compatibility with old
+	 * versions of ocfs2-tools which look for things in /sys/o2cb.
+	 */
+	ret = sysfs_create_link(NULL, &o2cb_kset->kobj, "o2cb");
+	if (ret)
+		goto error;
+
 	ret = sysfs_create_group(&o2cb_kset->kobj, &o2cb_attr_group);
 	if (ret)
 		goto error;
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index b8057c51b20..1e44ad14881 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -142,23 +142,65 @@ static void o2net_idle_timer(unsigned long data);
 static void o2net_sc_postpone_idle(struct o2net_sock_container *sc);
 static void o2net_sc_reset_idle_timer(struct o2net_sock_container *sc);
 
-/*
- * FIXME: These should use to_o2nm_cluster_from_node(), but we end up
- * losing our parent link to the cluster during shutdown. This can be
- * solved by adding a pre-removal callback to configfs, or passing
- * around the cluster with the node. -jeffm
- */
-static inline int o2net_reconnect_delay(struct o2nm_node *node)
+static void o2net_init_nst(struct o2net_send_tracking *nst, u32 msgtype,
+			   u32 msgkey, struct task_struct *task, u8 node)
+{
+#ifdef CONFIG_DEBUG_FS
+	INIT_LIST_HEAD(&nst->st_net_debug_item);
+	nst->st_task = task;
+	nst->st_msg_type = msgtype;
+	nst->st_msg_key = msgkey;
+	nst->st_node = node;
+#endif
+}
+
+static void o2net_set_nst_sock_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+	do_gettimeofday(&nst->st_sock_time);
+#endif
+}
+
+static void o2net_set_nst_send_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+	do_gettimeofday(&nst->st_send_time);
+#endif
+}
+
+static void o2net_set_nst_status_time(struct o2net_send_tracking *nst)
+{
+#ifdef CONFIG_DEBUG_FS
+	do_gettimeofday(&nst->st_status_time);
+#endif
+}
+
+static void o2net_set_nst_sock_container(struct o2net_send_tracking *nst,
+					 struct o2net_sock_container *sc)
+{
+#ifdef CONFIG_DEBUG_FS
+	nst->st_sc = sc;
+#endif
+}
+
+static void o2net_set_nst_msg_id(struct o2net_send_tracking *nst, u32 msg_id)
+{
+#ifdef CONFIG_DEBUG_FS
+	nst->st_id = msg_id;
+#endif
+}
+
+static inline int o2net_reconnect_delay(void)
 {
 	return o2nm_single_cluster->cl_reconnect_delay_ms;
 }
 
-static inline int o2net_keepalive_delay(struct o2nm_node *node)
+static inline int o2net_keepalive_delay(void)
 {
 	return o2nm_single_cluster->cl_keepalive_delay_ms;
 }
 
-static inline int o2net_idle_timeout(struct o2nm_node *node)
+static inline int o2net_idle_timeout(void)
 {
 	return o2nm_single_cluster->cl_idle_timeout_ms;
 }
@@ -296,6 +338,7 @@ static void sc_kref_release(struct kref *kref)
 	o2nm_node_put(sc->sc_node);
 	sc->sc_node = NULL;
 
+	o2net_debug_del_sc(sc);
 	kfree(sc);
 }
 
@@ -336,6 +379,7 @@ static struct o2net_sock_container *sc_alloc(struct o2nm_node *node)
 
 	ret = sc;
 	sc->sc_page = page;
+	o2net_debug_add_sc(sc);
 	sc = NULL;
 	page = NULL;
 
@@ -399,8 +443,6 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 	mlog_bug_on_msg(err && valid, "err %d valid %u\n", err, valid);
 	mlog_bug_on_msg(valid && !sc, "valid %u sc %p\n", valid, sc);
 
-	/* we won't reconnect after our valid conn goes away for
-	 * this hb iteration.. here so it shows up in the logs */
 	if (was_valid && !valid && err == 0)
 		err = -ENOTCONN;
 
@@ -430,11 +472,6 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 
 	if (!was_valid && valid) {
 		o2quo_conn_up(o2net_num_from_nn(nn));
-		/* this is a bit of a hack.  we only try reconnecting
-		 * when heartbeating starts until we get a connection.
-		 * if that connection then dies we don't try reconnecting.
-		 * the only way to start connecting again is to down
-		 * heartbeat and bring it back up. */
 		cancel_delayed_work(&nn->nn_connect_expired);
 		printk(KERN_INFO "o2net: %s " SC_NODEF_FMT "\n",
 		       o2nm_this_node() > sc->sc_node->nd_num ?
@@ -451,12 +488,24 @@ static void o2net_set_nn_state(struct o2net_node *nn,
 		/* delay if we're withing a RECONNECT_DELAY of the
 		 * last attempt */
 		delay = (nn->nn_last_connect_attempt +
-			 msecs_to_jiffies(o2net_reconnect_delay(NULL)))
+			 msecs_to_jiffies(o2net_reconnect_delay()))
 			- jiffies;
-		if (delay > msecs_to_jiffies(o2net_reconnect_delay(NULL)))
+		if (delay > msecs_to_jiffies(o2net_reconnect_delay()))
 			delay = 0;
 		mlog(ML_CONN, "queueing conn attempt in %lu jiffies\n", delay);
 		queue_delayed_work(o2net_wq, &nn->nn_connect_work, delay);
+
+		/*
+		 * Delay the expired work after idle timeout.
+		 *
+		 * We might have lots of failed connection attempts that run
+		 * through here but we only cancel the connect_expired work when
+		 * a connection attempt succeeds.  So only the first enqueue of
+		 * the connect_expired work will do anything.  The rest will see
+		 * that it's already queued and do nothing.
+		 */
+		delay += msecs_to_jiffies(o2net_idle_timeout());
+		queue_delayed_work(o2net_wq, &nn->nn_connect_expired, delay);
 	}
 
 	/* keep track of the nn's sc ref for the caller */
@@ -914,6 +963,9 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 	struct o2net_status_wait nsw = {
 		.ns_node_item = LIST_HEAD_INIT(nsw.ns_node_item),
 	};
+	struct o2net_send_tracking nst;
+
+	o2net_init_nst(&nst, msg_type, key, current, target_node);
 
 	if (o2net_wq == NULL) {
 		mlog(0, "attempt to tx without o2netd running\n");
@@ -939,6 +991,10 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 		goto out;
 	}
 
+	o2net_debug_add_nst(&nst);
+
+	o2net_set_nst_sock_time(&nst);
+
 	ret = wait_event_interruptible(nn->nn_sc_wq,
 				       o2net_tx_can_proceed(nn, &sc, &error));
 	if (!ret && error)
@@ -946,6 +1002,8 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 	if (ret)
 		goto out;
 
+	o2net_set_nst_sock_container(&nst, sc);
+
 	veclen = caller_veclen + 1;
 	vec = kmalloc(sizeof(struct kvec) * veclen, GFP_ATOMIC);
 	if (vec == NULL) {
@@ -972,6 +1030,9 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 		goto out;
 
 	msg->msg_num = cpu_to_be32(nsw.ns_id);
+	o2net_set_nst_msg_id(&nst, nsw.ns_id);
+
+	o2net_set_nst_send_time(&nst);
 
 	/* finally, convert the message header to network byte-order
 	 * and send */
@@ -986,6 +1047,7 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 	}
 
 	/* wait on other node's handler */
+	o2net_set_nst_status_time(&nst);
 	wait_event(nsw.ns_wq, o2net_nsw_completed(nn, &nsw));
 
 	/* Note that we avoid overwriting the callers status return
@@ -998,6 +1060,7 @@ int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
 	mlog(0, "woken, returning system status %d, user status %d\n",
 	     ret, nsw.ns_status);
 out:
+	o2net_debug_del_nst(&nst); /* must be before dropping sc and node */
 	if (sc)
 		sc_put(sc);
 	if (vec)
@@ -1154,23 +1217,23 @@ static int o2net_check_handshake(struct o2net_sock_container *sc)
 	 * but isn't. This can ultimately cause corruption.
 	 */
 	if (be32_to_cpu(hand->o2net_idle_timeout_ms) !=
-				o2net_idle_timeout(sc->sc_node)) {
+				o2net_idle_timeout()) {
 		mlog(ML_NOTICE, SC_NODEF_FMT " uses a network idle timeout of "
 		     "%u ms, but we use %u ms locally.  disconnecting\n",
 		     SC_NODEF_ARGS(sc),
 		     be32_to_cpu(hand->o2net_idle_timeout_ms),
-		     o2net_idle_timeout(sc->sc_node));
+		     o2net_idle_timeout());
 		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
 		return -1;
 	}
 
 	if (be32_to_cpu(hand->o2net_keepalive_delay_ms) !=
-			o2net_keepalive_delay(sc->sc_node)) {
+			o2net_keepalive_delay()) {
 		mlog(ML_NOTICE, SC_NODEF_FMT " uses a keepalive delay of "
 		     "%u ms, but we use %u ms locally.  disconnecting\n",
 		     SC_NODEF_ARGS(sc),
 		     be32_to_cpu(hand->o2net_keepalive_delay_ms),
-		     o2net_keepalive_delay(sc->sc_node));
+		     o2net_keepalive_delay());
 		o2net_ensure_shutdown(nn, sc, -ENOTCONN);
 		return -1;
 	}
@@ -1193,6 +1256,7 @@ static int o2net_check_handshake(struct o2net_sock_container *sc)
 	 * shut down already */
 	if (nn->nn_sc == sc) {
 		o2net_sc_reset_idle_timer(sc);
+		atomic_set(&nn->nn_timeout, 0);
 		o2net_set_nn_state(nn, sc, 1, 0);
 	}
 	spin_unlock(&nn->nn_lock);
@@ -1347,12 +1411,11 @@ static void o2net_initialize_handshake(void)
 {
 	o2net_hand->o2hb_heartbeat_timeout_ms = cpu_to_be32(
 		O2HB_MAX_WRITE_TIMEOUT_MS);
-	o2net_hand->o2net_idle_timeout_ms = cpu_to_be32(
-		o2net_idle_timeout(NULL));
+	o2net_hand->o2net_idle_timeout_ms = cpu_to_be32(o2net_idle_timeout());
 	o2net_hand->o2net_keepalive_delay_ms = cpu_to_be32(
-		o2net_keepalive_delay(NULL));
+		o2net_keepalive_delay());
 	o2net_hand->o2net_reconnect_delay_ms = cpu_to_be32(
-		o2net_reconnect_delay(NULL));
+		o2net_reconnect_delay());
 }
 
 /* ------------------------------------------------------------ */
@@ -1391,14 +1454,15 @@ static void o2net_sc_send_keep_req(struct work_struct *work)
 static void o2net_idle_timer(unsigned long data)
 {
 	struct o2net_sock_container *sc = (struct o2net_sock_container *)data;
+	struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
 	struct timeval now;
 
 	do_gettimeofday(&now);
 
 	printk(KERN_INFO "o2net: connection to " SC_NODEF_FMT " has been idle for %u.%u "
 	     "seconds, shutting it down.\n", SC_NODEF_ARGS(sc),
-		     o2net_idle_timeout(sc->sc_node) / 1000,
-		     o2net_idle_timeout(sc->sc_node) % 1000);
+		     o2net_idle_timeout() / 1000,
+		     o2net_idle_timeout() % 1000);
 	mlog(ML_NOTICE, "here are some times that might help debug the "
 	     "situation: (tmr %ld.%ld now %ld.%ld dr %ld.%ld adv "
 	     "%ld.%ld:%ld.%ld func (%08x:%u) %ld.%ld:%ld.%ld)\n",
@@ -1413,6 +1477,12 @@ static void o2net_idle_timer(unsigned long data)
 	     sc->sc_tv_func_start.tv_sec, (long) sc->sc_tv_func_start.tv_usec,
 	     sc->sc_tv_func_stop.tv_sec, (long) sc->sc_tv_func_stop.tv_usec);
 
+	/*
+	 * Initialize the nn_timeout so that the next connection attempt
+	 * will continue in o2net_start_connect.
+	 */
+	atomic_set(&nn->nn_timeout, 1);
+
 	o2net_sc_queue_work(sc, &sc->sc_shutdown_work);
 }
 
@@ -1420,10 +1490,10 @@ static void o2net_sc_reset_idle_timer(struct o2net_sock_container *sc)
 {
 	o2net_sc_cancel_delayed_work(sc, &sc->sc_keepalive_work);
 	o2net_sc_queue_delayed_work(sc, &sc->sc_keepalive_work,
-		      msecs_to_jiffies(o2net_keepalive_delay(sc->sc_node)));
+		      msecs_to_jiffies(o2net_keepalive_delay()));
 	do_gettimeofday(&sc->sc_tv_timer);
 	mod_timer(&sc->sc_idle_timeout,
-	       jiffies + msecs_to_jiffies(o2net_idle_timeout(sc->sc_node)));
+	       jiffies + msecs_to_jiffies(o2net_idle_timeout()));
 }
 
 static void o2net_sc_postpone_idle(struct o2net_sock_container *sc)
@@ -1447,6 +1517,7 @@ static void o2net_start_connect(struct work_struct *work)
 	struct socket *sock = NULL;
 	struct sockaddr_in myaddr = {0, }, remoteaddr = {0, };
 	int ret = 0, stop;
+	unsigned int timeout;
 
 	/* if we're greater we initiate tx, otherwise we accept */
 	if (o2nm_this_node() <= o2net_num_from_nn(nn))
@@ -1466,8 +1537,17 @@ static void o2net_start_connect(struct work_struct *work)
 	}
 
 	spin_lock(&nn->nn_lock);
-	/* see if we already have one pending or have given up */
-	stop = (nn->nn_sc || nn->nn_persistent_error);
+	/*
+	 * see if we already have one pending or have given up.
+	 * For nn_timeout, it is set when we close the connection
+	 * because of the idle time out. So it means that we have
+	 * at least connected to that node successfully once,
+	 * now try to connect to it again.
+	 */
+	timeout = atomic_read(&nn->nn_timeout);
+	stop = (nn->nn_sc ||
+		(nn->nn_persistent_error &&
+		(nn->nn_persistent_error != -ENOTCONN || timeout == 0)));
 	spin_unlock(&nn->nn_lock);
 	if (stop)
 		goto out;
@@ -1555,8 +1635,8 @@ static void o2net_connect_expired(struct work_struct *work)
 		mlog(ML_ERROR, "no connection established with node %u after "
 		     "%u.%u seconds, giving up and returning errors.\n",
 		     o2net_num_from_nn(nn),
-		     o2net_idle_timeout(NULL) / 1000,
-		     o2net_idle_timeout(NULL) % 1000);
+		     o2net_idle_timeout() / 1000,
+		     o2net_idle_timeout() % 1000);
 
 		o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
 	}
@@ -1579,6 +1659,7 @@ void o2net_disconnect_node(struct o2nm_node *node)
 
 	/* don't reconnect until it's heartbeating again */
 	spin_lock(&nn->nn_lock);
+	atomic_set(&nn->nn_timeout, 0);
 	o2net_set_nn_state(nn, NULL, 0, -ENOTCONN);
 	spin_unlock(&nn->nn_lock);
 
@@ -1610,20 +1691,15 @@ static void o2net_hb_node_up_cb(struct o2nm_node *node, int node_num,
 
 	/* ensure an immediate connect attempt */
 	nn->nn_last_connect_attempt = jiffies -
-		(msecs_to_jiffies(o2net_reconnect_delay(node)) + 1);
+		(msecs_to_jiffies(o2net_reconnect_delay()) + 1);
 
 	if (node_num != o2nm_this_node()) {
-		/* heartbeat doesn't work unless a local node number is
-		 * configured and doing so brings up the o2net_wq, so we can
-		 * use it.. */
-		queue_delayed_work(o2net_wq, &nn->nn_connect_expired,
-		                   msecs_to_jiffies(o2net_idle_timeout(node)));
-
 		/* believe it or not, accept and node hearbeating testing
 		 * can succeed for this node before we got here.. so
 		 * only use set_nn_state to clear the persistent error
 		 * if that hasn't already happened */
 		spin_lock(&nn->nn_lock);
+		atomic_set(&nn->nn_timeout, 0);
 		if (nn->nn_persistent_error)
 			o2net_set_nn_state(nn, NULL, 0, 0);
 		spin_unlock(&nn->nn_lock);
@@ -1747,6 +1823,7 @@ static int o2net_accept_one(struct socket *sock)
 	new_sock = NULL;
 
 	spin_lock(&nn->nn_lock);
+	atomic_set(&nn->nn_timeout, 0);
 	o2net_set_nn_state(nn, sc, 0, 0);
 	spin_unlock(&nn->nn_lock);
 
@@ -1922,6 +1999,9 @@ int o2net_init(void)
 
 	o2quo_init();
 
+	if (o2net_debugfs_init())
+		return -ENOMEM;
+
 	o2net_hand = kzalloc(sizeof(struct o2net_handshake), GFP_KERNEL);
 	o2net_keep_req = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
 	o2net_keep_resp = kzalloc(sizeof(struct o2net_msg), GFP_KERNEL);
@@ -1941,6 +2021,7 @@ int o2net_init(void)
 	for (i = 0; i < ARRAY_SIZE(o2net_nodes); i++) {
 		struct o2net_node *nn = o2net_nn_from_num(i);
 
+		atomic_set(&nn->nn_timeout, 0);
 		spin_lock_init(&nn->nn_lock);
 		INIT_DELAYED_WORK(&nn->nn_connect_work, o2net_start_connect);
 		INIT_DELAYED_WORK(&nn->nn_connect_expired,
@@ -1962,4 +2043,5 @@ void o2net_exit(void)
 	kfree(o2net_hand);
 	kfree(o2net_keep_req);
 	kfree(o2net_keep_resp);
+	o2net_debugfs_exit();
 }
diff --git a/fs/ocfs2/cluster/tcp.h b/fs/ocfs2/cluster/tcp.h
index f36f66aab3d..a705d5d1903 100644
--- a/fs/ocfs2/cluster/tcp.h
+++ b/fs/ocfs2/cluster/tcp.h
@@ -117,4 +117,36 @@ int o2net_num_connected_peers(void);
 int o2net_init(void);
 void o2net_exit(void);
 
+struct o2net_send_tracking;
+struct o2net_sock_container;
+
+#ifdef CONFIG_DEBUG_FS
+int o2net_debugfs_init(void);
+void o2net_debugfs_exit(void);
+void o2net_debug_add_nst(struct o2net_send_tracking *nst);
+void o2net_debug_del_nst(struct o2net_send_tracking *nst);
+void o2net_debug_add_sc(struct o2net_sock_container *sc);
+void o2net_debug_del_sc(struct o2net_sock_container *sc);
+#else
+static int o2net_debugfs_init(void)
+{
+	return 0;
+}
+static void o2net_debugfs_exit(void)
+{
+}
+static void o2net_debug_add_nst(struct o2net_send_tracking *nst)
+{
+}
+static void o2net_debug_del_nst(struct o2net_send_tracking *nst)
+{
+}
+static void o2net_debug_add_sc(struct o2net_sock_container *sc)
+{
+}
+static void o2net_debug_del_sc(struct o2net_sock_container *sc)
+{
+}
+#endif	/* CONFIG_DEBUG_FS */
+
 #endif /* O2CLUSTER_TCP_H */
diff --git a/fs/ocfs2/cluster/tcp_internal.h b/fs/ocfs2/cluster/tcp_internal.h
index d25b9af2850..8d58cfe410b 100644
--- a/fs/ocfs2/cluster/tcp_internal.h
+++ b/fs/ocfs2/cluster/tcp_internal.h
@@ -95,6 +95,8 @@ struct o2net_node {
 	unsigned			nn_sc_valid:1;
 	/* if this is set tx just returns it */
 	int				nn_persistent_error;
+	/* It is only set to 1 after the idle time out. */
+	atomic_t			nn_timeout;
 
 	/* threads waiting for an sc to arrive wait on the wq for generation
 	 * to increase.  it is increased when a connecting socket succeeds
@@ -164,7 +166,9 @@ struct o2net_sock_container {
 	/* original handlers for the sockets */
 	void			(*sc_state_change)(struct sock *sk);
 	void			(*sc_data_ready)(struct sock *sk, int bytes);
-
+#ifdef CONFIG_DEBUG_FS
+	struct list_head        sc_net_debug_item;
+#endif
 	struct timeval 		sc_tv_timer;
 	struct timeval 		sc_tv_data_ready;
 	struct timeval 		sc_tv_advance_start;
@@ -206,4 +210,24 @@ struct o2net_status_wait {
 	struct list_head	ns_node_item;
 };
 
+#ifdef CONFIG_DEBUG_FS
+/* just for state dumps */
+struct o2net_send_tracking {
+	struct list_head		st_net_debug_item;
+	struct task_struct		*st_task;
+	struct o2net_sock_container	*st_sc;
+	u32				st_id;
+	u32				st_msg_type;
+	u32				st_msg_key;
+	u8				st_node;
+	struct timeval			st_sock_time;
+	struct timeval			st_send_time;
+	struct timeval			st_status_time;
+};
+#else
+struct o2net_send_tracking {
+	u32	dummy;
+};
+#endif	/* CONFIG_DEBUG_FS */
+
 #endif /* O2CLUSTER_TCP_INTERNAL_H */
diff --git a/fs/ocfs2/dlm/Makefile b/fs/ocfs2/dlm/Makefile
index ce3f7c29d27..19036137570 100644
--- a/fs/ocfs2/dlm/Makefile
+++ b/fs/ocfs2/dlm/Makefile
@@ -1,6 +1,6 @@
 EXTRA_CFLAGS += -Ifs/ocfs2
 
-obj-$(CONFIG_OCFS2_FS) += ocfs2_dlm.o ocfs2_dlmfs.o
+obj-$(CONFIG_OCFS2_FS_O2CB) += 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
diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index dc8ea666efd..d5a86fb81a4 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -49,6 +49,41 @@
 /* Intended to make it easier for us to switch out hash functions */
 #define dlm_lockid_hash(_n, _l) full_name_hash(_n, _l)
 
+enum dlm_mle_type {
+	DLM_MLE_BLOCK,
+	DLM_MLE_MASTER,
+	DLM_MLE_MIGRATION
+};
+
+struct dlm_lock_name {
+	u8 len;
+	u8 name[DLM_LOCKID_NAME_MAX];
+};
+
+struct dlm_master_list_entry {
+	struct list_head list;
+	struct list_head hb_events;
+	struct dlm_ctxt *dlm;
+	spinlock_t spinlock;
+	wait_queue_head_t wq;
+	atomic_t woken;
+	struct kref mle_refs;
+	int inuse;
+	unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+	u8 master;
+	u8 new_master;
+	enum dlm_mle_type type;
+	struct o2hb_callback_func mle_hb_up;
+	struct o2hb_callback_func mle_hb_down;
+	union {
+		struct dlm_lock_resource *res;
+		struct dlm_lock_name name;
+	} u;
+};
+
 enum dlm_ast_type {
 	DLM_AST = 0,
 	DLM_BAST,
@@ -101,6 +136,7 @@ struct dlm_ctxt
 	struct list_head purge_list;
 	struct list_head pending_asts;
 	struct list_head pending_basts;
+	struct list_head tracking_list;
 	unsigned int purge_count;
 	spinlock_t spinlock;
 	spinlock_t ast_lock;
@@ -122,6 +158,9 @@ struct dlm_ctxt
 	atomic_t remote_resources;
 	atomic_t unknown_resources;
 
+	struct dlm_debug_ctxt *dlm_debug_ctxt;
+	struct dentry *dlm_debugfs_subroot;
+
 	/* NOTE: Next three are protected by dlm_domain_lock */
 	struct kref dlm_refs;
 	enum dlm_ctxt_state dlm_state;
@@ -270,6 +309,9 @@ struct dlm_lock_resource
 	struct list_head dirty;
 	struct list_head recovering; // dlm_recovery_ctxt.resources list
 
+	/* Added during init and removed during release */
+	struct list_head tracking;	/* dlm->tracking_list */
+
 	/* unused lock resources have their last_used stamped and are
 	 * put on a list for the dlm thread to run. */
 	unsigned long    last_used;
@@ -963,9 +1005,16 @@ static inline void __dlm_wait_on_lockres(struct dlm_lock_resource *res)
 					  DLM_LOCK_RES_MIGRATING));
 }
 
+/* create/destroy slab caches */
+int dlm_init_master_caches(void);
+void dlm_destroy_master_caches(void);
+
+int dlm_init_lock_cache(void);
+void dlm_destroy_lock_cache(void);
 
 int dlm_init_mle_cache(void);
 void dlm_destroy_mle_cache(void);
+
 void dlm_hb_event_notify_attached(struct dlm_ctxt *dlm, int idx, int node_up);
 int dlm_drop_lockres_ref(struct dlm_ctxt *dlm,
 			 struct dlm_lock_resource *res);
diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
index 64239b37e5d..5f6d858770a 100644
--- a/fs/ocfs2/dlm/dlmdebug.c
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -5,7 +5,7 @@
  *
  * debug functionality for the dlm
  *
- * Copyright (C) 2004 Oracle.  All rights reserved.
+ * Copyright (C) 2004, 2008 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
@@ -30,6 +30,7 @@
 #include <linux/utsname.h>
 #include <linux/sysctl.h>
 #include <linux/spinlock.h>
+#include <linux/debugfs.h>
 
 #include "cluster/heartbeat.h"
 #include "cluster/nodemanager.h"
@@ -37,17 +38,16 @@
 
 #include "dlmapi.h"
 #include "dlmcommon.h"
-
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #define MLOG_MASK_PREFIX ML_DLM
 #include "cluster/masklog.h"
 
+int stringify_lockname(const char *lockname, int locklen, char *buf, int len);
+
 void dlm_print_one_lock_resource(struct dlm_lock_resource *res)
 {
-	mlog(ML_NOTICE, "lockres: %.*s, owner=%u, state=%u\n",
-	       res->lockname.len, res->lockname.name,
-	       res->owner, res->state);
 	spin_lock(&res->spinlock);
 	__dlm_print_one_lock_resource(res);
 	spin_unlock(&res->spinlock);
@@ -58,7 +58,7 @@ static void dlm_print_lockres_refmap(struct dlm_lock_resource *res)
 	int bit;
 	assert_spin_locked(&res->spinlock);
 
-	mlog(ML_NOTICE, "  refmap nodes: [ ");
+	printk("  refmap nodes: [ ");
 	bit = 0;
 	while (1) {
 		bit = find_next_bit(res->refmap, O2NM_MAX_NODES, bit);
@@ -70,63 +70,66 @@ static void dlm_print_lockres_refmap(struct dlm_lock_resource *res)
 	printk("], inflight=%u\n", res->inflight_locks);
 }
 
+static void __dlm_print_lock(struct dlm_lock *lock)
+{
+	spin_lock(&lock->spinlock);
+
+	printk("    type=%d, conv=%d, node=%u, cookie=%u:%llu, "
+	       "ref=%u, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c), "
+	       "pending=(conv=%c,lock=%c,cancel=%c,unlock=%c)\n",
+	       lock->ml.type, lock->ml.convert_type, lock->ml.node,
+	       dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+	       dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+	       atomic_read(&lock->lock_refs.refcount),
+	       (list_empty(&lock->ast_list) ? 'y' : 'n'),
+	       (lock->ast_pending ? 'y' : 'n'),
+	       (list_empty(&lock->bast_list) ? 'y' : 'n'),
+	       (lock->bast_pending ? 'y' : 'n'),
+	       (lock->convert_pending ? 'y' : 'n'),
+	       (lock->lock_pending ? 'y' : 'n'),
+	       (lock->cancel_pending ? 'y' : 'n'),
+	       (lock->unlock_pending ? 'y' : 'n'));
+
+	spin_unlock(&lock->spinlock);
+}
+
 void __dlm_print_one_lock_resource(struct dlm_lock_resource *res)
 {
 	struct list_head *iter2;
 	struct dlm_lock *lock;
+	char buf[DLM_LOCKID_NAME_MAX];
 
 	assert_spin_locked(&res->spinlock);
 
-	mlog(ML_NOTICE, "lockres: %.*s, owner=%u, state=%u\n",
-	       res->lockname.len, res->lockname.name,
-	       res->owner, res->state);
-	mlog(ML_NOTICE, "  last used: %lu, on purge list: %s\n",
-	     res->last_used, list_empty(&res->purge) ? "no" : "yes");
+	stringify_lockname(res->lockname.name, res->lockname.len,
+			   buf, sizeof(buf) - 1);
+	printk("lockres: %s, owner=%u, state=%u\n",
+	       buf, res->owner, res->state);
+	printk("  last used: %lu, refcnt: %u, on purge list: %s\n",
+	       res->last_used, atomic_read(&res->refs.refcount),
+	       list_empty(&res->purge) ? "no" : "yes");
+	printk("  on dirty list: %s, on reco list: %s, "
+	       "migrating pending: %s\n",
+	       list_empty(&res->dirty) ? "no" : "yes",
+	       list_empty(&res->recovering) ? "no" : "yes",
+	       res->migration_pending ? "yes" : "no");
+	printk("  inflight locks: %d, asts reserved: %d\n",
+	       res->inflight_locks, atomic_read(&res->asts_reserved));
 	dlm_print_lockres_refmap(res);
-	mlog(ML_NOTICE, "  granted queue: \n");
+	printk("  granted queue:\n");
 	list_for_each(iter2, &res->granted) {
 		lock = list_entry(iter2, struct dlm_lock, list);
-		spin_lock(&lock->spinlock);
-		mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-		       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-		       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-		       list_empty(&lock->ast_list) ? 'y' : 'n',
-		       lock->ast_pending ? 'y' : 'n',
-		       list_empty(&lock->bast_list) ? 'y' : 'n',
-		       lock->bast_pending ? 'y' : 'n');
-		spin_unlock(&lock->spinlock);
+		__dlm_print_lock(lock);
 	}
-	mlog(ML_NOTICE, "  converting queue: \n");
+	printk("  converting queue:\n");
 	list_for_each(iter2, &res->converting) {
 		lock = list_entry(iter2, struct dlm_lock, list);
-		spin_lock(&lock->spinlock);
-		mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-		       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-		       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-		       list_empty(&lock->ast_list) ? 'y' : 'n',
-		       lock->ast_pending ? 'y' : 'n',
-		       list_empty(&lock->bast_list) ? 'y' : 'n',
-		       lock->bast_pending ? 'y' : 'n');
-		spin_unlock(&lock->spinlock);
+		__dlm_print_lock(lock);
 	}
-	mlog(ML_NOTICE, "  blocked queue: \n");
+	printk("  blocked queue:\n");
 	list_for_each(iter2, &res->blocked) {
 		lock = list_entry(iter2, struct dlm_lock, list);
-		spin_lock(&lock->spinlock);
-		mlog(ML_NOTICE, "    type=%d, conv=%d, node=%u, "
-		       "cookie=%u:%llu, ast=(empty=%c,pend=%c), bast=(empty=%c,pend=%c)\n", 
-		       lock->ml.type, lock->ml.convert_type, lock->ml.node, 
-		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
-		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
-		       list_empty(&lock->ast_list) ? 'y' : 'n',
-		       lock->ast_pending ? 'y' : 'n',
-		       list_empty(&lock->bast_list) ? 'y' : 'n',
-		       lock->bast_pending ? 'y' : 'n');
-		spin_unlock(&lock->spinlock);
+		__dlm_print_lock(lock);
 	}
 }
 
@@ -136,31 +139,6 @@ void dlm_print_one_lock(struct dlm_lock *lockid)
 }
 EXPORT_SYMBOL_GPL(dlm_print_one_lock);
 
-#if 0
-void dlm_dump_lock_resources(struct dlm_ctxt *dlm)
-{
-	struct dlm_lock_resource *res;
-	struct hlist_node *iter;
-	struct hlist_head *bucket;
-	int i;
-
-	mlog(ML_NOTICE, "struct dlm_ctxt: %s, node=%u, key=%u\n",
-		  dlm->name, dlm->node_num, dlm->key);
-	if (!dlm || !dlm->name) {
-		mlog(ML_ERROR, "dlm=%p\n", dlm);
-		return;
-	}
-
-	spin_lock(&dlm->spinlock);
-	for (i=0; i<DLM_HASH_BUCKETS; i++) {
-		bucket = dlm_lockres_hash(dlm, i);
-		hlist_for_each_entry(res, iter, bucket, hash_node)
-			dlm_print_one_lock_resource(res);
-	}
-	spin_unlock(&dlm->spinlock);
-}
-#endif  /*  0  */
-
 static const char *dlm_errnames[] = {
 	[DLM_NORMAL] =			"DLM_NORMAL",
 	[DLM_GRANTED] =			"DLM_GRANTED",
@@ -266,3 +244,792 @@ const char *dlm_errname(enum dlm_status err)
 	return dlm_errnames[err];
 }
 EXPORT_SYMBOL_GPL(dlm_errname);
+
+/* NOTE: This function converts a lockname into a string. It uses knowledge
+ * of the format of the lockname that should be outside the purview of the dlm.
+ * We are adding only to make dlm debugging slightly easier.
+ *
+ * For more on lockname formats, please refer to dlmglue.c and ocfs2_lockid.h.
+ */
+int stringify_lockname(const char *lockname, int locklen, char *buf, int len)
+{
+	int out = 0;
+	__be64 inode_blkno_be;
+
+#define OCFS2_DENTRY_LOCK_INO_START	18
+	if (*lockname == 'N') {
+		memcpy((__be64 *)&inode_blkno_be,
+		       (char *)&lockname[OCFS2_DENTRY_LOCK_INO_START],
+		       sizeof(__be64));
+		out += snprintf(buf + out, len - out, "%.*s%08x",
+				OCFS2_DENTRY_LOCK_INO_START - 1, lockname,
+				(unsigned int)be64_to_cpu(inode_blkno_be));
+	} else
+		out += snprintf(buf + out, len - out, "%.*s",
+				locklen, lockname);
+	return out;
+}
+
+static int stringify_nodemap(unsigned long *nodemap, int maxnodes,
+			     char *buf, int len)
+{
+	int out = 0;
+	int i = -1;
+
+	while ((i = find_next_bit(nodemap, maxnodes, i + 1)) < maxnodes)
+		out += snprintf(buf + out, len - out, "%d ", i);
+
+	return out;
+}
+
+static int dump_mle(struct dlm_master_list_entry *mle, char *buf, int len)
+{
+	int out = 0;
+	unsigned int namelen;
+	const char *name;
+	char *mle_type;
+
+	if (mle->type != DLM_MLE_MASTER) {
+		namelen = mle->u.name.len;
+		name = mle->u.name.name;
+	} else {
+		namelen = mle->u.res->lockname.len;
+		name = mle->u.res->lockname.name;
+	}
+
+	if (mle->type == DLM_MLE_BLOCK)
+		mle_type = "BLK";
+	else if (mle->type == DLM_MLE_MASTER)
+		mle_type = "MAS";
+	else
+		mle_type = "MIG";
+
+	out += stringify_lockname(name, namelen, buf + out, len - out);
+	out += snprintf(buf + out, len - out,
+			"\t%3s\tmas=%3u\tnew=%3u\tevt=%1d\tuse=%1d\tref=%3d\n",
+			mle_type, mle->master, mle->new_master,
+			!list_empty(&mle->hb_events),
+			!!mle->inuse,
+			atomic_read(&mle->mle_refs.refcount));
+
+	out += snprintf(buf + out, len - out, "Maybe=");
+	out += stringify_nodemap(mle->maybe_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+	out += snprintf(buf + out, len - out, "Vote=");
+	out += stringify_nodemap(mle->vote_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+	out += snprintf(buf + out, len - out, "Response=");
+	out += stringify_nodemap(mle->response_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+	out += snprintf(buf + out, len - out, "Node=");
+	out += stringify_nodemap(mle->node_map, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+	out += snprintf(buf + out, len - out, "\n");
+
+	return out;
+}
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle)
+{
+	char *buf;
+
+	buf = (char *) get_zeroed_page(GFP_NOFS);
+	if (buf) {
+		dump_mle(mle, buf, PAGE_SIZE - 1);
+		free_page((unsigned long)buf);
+	}
+}
+
+#ifdef CONFIG_DEBUG_FS
+
+static struct dentry *dlm_debugfs_root = NULL;
+
+#define DLM_DEBUGFS_DIR				"o2dlm"
+#define DLM_DEBUGFS_DLM_STATE			"dlm_state"
+#define DLM_DEBUGFS_LOCKING_STATE		"locking_state"
+#define DLM_DEBUGFS_MLE_STATE			"mle_state"
+#define DLM_DEBUGFS_PURGE_LIST			"purge_list"
+
+/* begin - utils funcs */
+static void dlm_debug_free(struct kref *kref)
+{
+	struct dlm_debug_ctxt *dc;
+
+	dc = container_of(kref, struct dlm_debug_ctxt, debug_refcnt);
+
+	kfree(dc);
+}
+
+void dlm_debug_put(struct dlm_debug_ctxt *dc)
+{
+	if (dc)
+		kref_put(&dc->debug_refcnt, dlm_debug_free);
+}
+
+static void dlm_debug_get(struct dlm_debug_ctxt *dc)
+{
+	kref_get(&dc->debug_refcnt);
+}
+
+static struct debug_buffer *debug_buffer_allocate(void)
+{
+	struct debug_buffer *db = NULL;
+
+	db = kzalloc(sizeof(struct debug_buffer), GFP_KERNEL);
+	if (!db)
+		goto bail;
+
+	db->len = PAGE_SIZE;
+	db->buf = kmalloc(db->len, GFP_KERNEL);
+	if (!db->buf)
+		goto bail;
+
+	return db;
+bail:
+	kfree(db);
+	return NULL;
+}
+
+static ssize_t debug_buffer_read(struct file *file, char __user *buf,
+				 size_t nbytes, loff_t *ppos)
+{
+	struct debug_buffer *db = file->private_data;
+
+	return simple_read_from_buffer(buf, nbytes, ppos, db->buf, db->len);
+}
+
+static loff_t debug_buffer_llseek(struct file *file, loff_t off, int whence)
+{
+	struct debug_buffer *db = file->private_data;
+	loff_t new = -1;
+
+	switch (whence) {
+	case 0:
+		new = off;
+		break;
+	case 1:
+		new = file->f_pos + off;
+		break;
+	}
+
+	if (new < 0 || new > db->len)
+		return -EINVAL;
+
+	return (file->f_pos = new);
+}
+
+static int debug_buffer_release(struct inode *inode, struct file *file)
+{
+	struct debug_buffer *db = (struct debug_buffer *)file->private_data;
+
+	if (db)
+		kfree(db->buf);
+	kfree(db);
+
+	return 0;
+}
+/* end - util funcs */
+
+/* begin - purge list funcs */
+static int debug_purgelist_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+	struct dlm_lock_resource *res;
+	int out = 0;
+	unsigned long total = 0;
+
+	out += snprintf(db->buf + out, db->len - out,
+			"Dumping Purgelist for Domain: %s\n", dlm->name);
+
+	spin_lock(&dlm->spinlock);
+	list_for_each_entry(res, &dlm->purge_list, purge) {
+		++total;
+		if (db->len - out < 100)
+			continue;
+		spin_lock(&res->spinlock);
+		out += stringify_lockname(res->lockname.name,
+					  res->lockname.len,
+					  db->buf + out, db->len - out);
+		out += snprintf(db->buf + out, db->len - out, "\t%ld\n",
+				(jiffies - res->last_used)/HZ);
+		spin_unlock(&res->spinlock);
+	}
+	spin_unlock(&dlm->spinlock);
+
+	out += snprintf(db->buf + out, db->len - out,
+			"Total on list: %ld\n", total);
+
+	return out;
+}
+
+static int debug_purgelist_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	struct debug_buffer *db;
+
+	db = debug_buffer_allocate();
+	if (!db)
+		goto bail;
+
+	db->len = debug_purgelist_print(dlm, db);
+
+	file->private_data = db;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static struct file_operations debug_purgelist_fops = {
+	.open =		debug_purgelist_open,
+	.release =	debug_buffer_release,
+	.read =		debug_buffer_read,
+	.llseek =	debug_buffer_llseek,
+};
+/* end - purge list funcs */
+
+/* begin - debug mle funcs */
+static int debug_mle_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+	struct dlm_master_list_entry *mle;
+	int out = 0;
+	unsigned long total = 0;
+
+	out += snprintf(db->buf + out, db->len - out,
+			"Dumping MLEs for Domain: %s\n", dlm->name);
+
+	spin_lock(&dlm->master_lock);
+	list_for_each_entry(mle, &dlm->master_list, list) {
+		++total;
+		if (db->len - out < 200)
+			continue;
+		out += dump_mle(mle, db->buf + out, db->len - out);
+	}
+	spin_unlock(&dlm->master_lock);
+
+	out += snprintf(db->buf + out, db->len - out,
+			"Total on list: %ld\n", total);
+	return out;
+}
+
+static int debug_mle_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	struct debug_buffer *db;
+
+	db = debug_buffer_allocate();
+	if (!db)
+		goto bail;
+
+	db->len = debug_mle_print(dlm, db);
+
+	file->private_data = db;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static struct file_operations debug_mle_fops = {
+	.open =		debug_mle_open,
+	.release =	debug_buffer_release,
+	.read =		debug_buffer_read,
+	.llseek =	debug_buffer_llseek,
+};
+
+/* end - debug mle funcs */
+
+/* begin - debug lockres funcs */
+static int dump_lock(struct dlm_lock *lock, int list_type, char *buf, int len)
+{
+	int out;
+
+#define DEBUG_LOCK_VERSION	1
+	spin_lock(&lock->spinlock);
+	out = snprintf(buf, len, "LOCK:%d,%d,%d,%d,%d,%d:%lld,%d,%d,%d,%d,%d,"
+		       "%d,%d,%d,%d\n",
+		       DEBUG_LOCK_VERSION,
+		       list_type, lock->ml.type, lock->ml.convert_type,
+		       lock->ml.node,
+		       dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
+		       dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
+		       !list_empty(&lock->ast_list),
+		       !list_empty(&lock->bast_list),
+		       lock->ast_pending, lock->bast_pending,
+		       lock->convert_pending, lock->lock_pending,
+		       lock->cancel_pending, lock->unlock_pending,
+		       atomic_read(&lock->lock_refs.refcount));
+	spin_unlock(&lock->spinlock);
+
+	return out;
+}
+
+static int dump_lockres(struct dlm_lock_resource *res, char *buf, int len)
+{
+	struct dlm_lock *lock;
+	int i;
+	int out = 0;
+
+	out += snprintf(buf + out, len - out, "NAME:");
+	out += stringify_lockname(res->lockname.name, res->lockname.len,
+				  buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+#define DEBUG_LRES_VERSION	1
+	out += snprintf(buf + out, len - out,
+			"LRES:%d,%d,%d,%ld,%d,%d,%d,%d,%d,%d,%d\n",
+			DEBUG_LRES_VERSION,
+			res->owner, res->state, res->last_used,
+			!list_empty(&res->purge),
+			!list_empty(&res->dirty),
+			!list_empty(&res->recovering),
+			res->inflight_locks, res->migration_pending,
+			atomic_read(&res->asts_reserved),
+			atomic_read(&res->refs.refcount));
+
+	/* refmap */
+	out += snprintf(buf + out, len - out, "RMAP:");
+	out += stringify_nodemap(res->refmap, O2NM_MAX_NODES,
+				 buf + out, len - out);
+	out += snprintf(buf + out, len - out, "\n");
+
+	/* lvb */
+	out += snprintf(buf + out, len - out, "LVBX:");
+	for (i = 0; i < DLM_LVB_LEN; i++)
+		out += snprintf(buf + out, len - out,
+					"%02x", (unsigned char)res->lvb[i]);
+	out += snprintf(buf + out, len - out, "\n");
+
+	/* granted */
+	list_for_each_entry(lock, &res->granted, list)
+		out += dump_lock(lock, 0, buf + out, len - out);
+
+	/* converting */
+	list_for_each_entry(lock, &res->converting, list)
+		out += dump_lock(lock, 1, buf + out, len - out);
+
+	/* blocked */
+	list_for_each_entry(lock, &res->blocked, list)
+		out += dump_lock(lock, 2, buf + out, len - out);
+
+	out += snprintf(buf + out, len - out, "\n");
+
+	return out;
+}
+
+static void *lockres_seq_start(struct seq_file *m, loff_t *pos)
+{
+	struct debug_lockres *dl = m->private;
+	struct dlm_ctxt *dlm = dl->dl_ctxt;
+	struct dlm_lock_resource *res = NULL;
+
+	spin_lock(&dlm->spinlock);
+
+	if (dl->dl_res) {
+		list_for_each_entry(res, &dl->dl_res->tracking, tracking) {
+			if (dl->dl_res) {
+				dlm_lockres_put(dl->dl_res);
+				dl->dl_res = NULL;
+			}
+			if (&res->tracking == &dlm->tracking_list) {
+				mlog(0, "End of list found, %p\n", res);
+				dl = NULL;
+				break;
+			}
+			dlm_lockres_get(res);
+			dl->dl_res = res;
+			break;
+		}
+	} else {
+		if (!list_empty(&dlm->tracking_list)) {
+			list_for_each_entry(res, &dlm->tracking_list, tracking)
+				break;
+			dlm_lockres_get(res);
+			dl->dl_res = res;
+		} else
+			dl = NULL;
+	}
+
+	if (dl) {
+		spin_lock(&dl->dl_res->spinlock);
+		dump_lockres(dl->dl_res, dl->dl_buf, dl->dl_len - 1);
+		spin_unlock(&dl->dl_res->spinlock);
+	}
+
+	spin_unlock(&dlm->spinlock);
+
+	return dl;
+}
+
+static void lockres_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static void *lockres_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return NULL;
+}
+
+static int lockres_seq_show(struct seq_file *s, void *v)
+{
+	struct debug_lockres *dl = (struct debug_lockres *)v;
+
+	seq_printf(s, "%s", dl->dl_buf);
+
+	return 0;
+}
+
+static struct seq_operations debug_lockres_ops = {
+	.start =	lockres_seq_start,
+	.stop =		lockres_seq_stop,
+	.next =		lockres_seq_next,
+	.show =		lockres_seq_show,
+};
+
+static int debug_lockres_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	int ret = -ENOMEM;
+	struct seq_file *seq;
+	struct debug_lockres *dl = NULL;
+
+	dl = kzalloc(sizeof(struct debug_lockres), GFP_KERNEL);
+	if (!dl) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	dl->dl_len = PAGE_SIZE;
+	dl->dl_buf = kmalloc(dl->dl_len, GFP_KERNEL);
+	if (!dl->dl_buf) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	ret = seq_open(file, &debug_lockres_ops);
+	if (ret) {
+		mlog_errno(ret);
+		goto bail;
+	}
+
+	seq = (struct seq_file *) file->private_data;
+	seq->private = dl;
+
+	dlm_grab(dlm);
+	dl->dl_ctxt = dlm;
+
+	return 0;
+bail:
+	if (dl)
+		kfree(dl->dl_buf);
+	kfree(dl);
+	return ret;
+}
+
+static int debug_lockres_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq = (struct seq_file *)file->private_data;
+	struct debug_lockres *dl = (struct debug_lockres *)seq->private;
+
+	if (dl->dl_res)
+		dlm_lockres_put(dl->dl_res);
+	dlm_put(dl->dl_ctxt);
+	kfree(dl->dl_buf);
+	return seq_release_private(inode, file);
+}
+
+static struct file_operations debug_lockres_fops = {
+	.open =		debug_lockres_open,
+	.release =	debug_lockres_release,
+	.read =		seq_read,
+	.llseek =	seq_lseek,
+};
+/* end - debug lockres funcs */
+
+/* begin - debug state funcs */
+static int debug_state_print(struct dlm_ctxt *dlm, struct debug_buffer *db)
+{
+	int out = 0;
+	struct dlm_reco_node_data *node;
+	char *state;
+	int lres, rres, ures, tres;
+
+	lres = atomic_read(&dlm->local_resources);
+	rres = atomic_read(&dlm->remote_resources);
+	ures = atomic_read(&dlm->unknown_resources);
+	tres = lres + rres + ures;
+
+	spin_lock(&dlm->spinlock);
+
+	switch (dlm->dlm_state) {
+	case DLM_CTXT_NEW:
+		state = "NEW"; break;
+	case DLM_CTXT_JOINED:
+		state = "JOINED"; break;
+	case DLM_CTXT_IN_SHUTDOWN:
+		state = "SHUTDOWN"; break;
+	case DLM_CTXT_LEAVING:
+		state = "LEAVING"; break;
+	default:
+		state = "UNKNOWN"; break;
+	}
+
+	/* Domain: xxxxxxxxxx  Key: 0xdfbac769 */
+	out += snprintf(db->buf + out, db->len - out,
+			"Domain: %s  Key: 0x%08x\n", dlm->name, dlm->key);
+
+	/* Thread Pid: xxx  Node: xxx  State: xxxxx */
+	out += snprintf(db->buf + out, db->len - out,
+			"Thread Pid: %d  Node: %d  State: %s\n",
+			dlm->dlm_thread_task->pid, dlm->node_num, state);
+
+	/* Number of Joins: xxx  Joining Node: xxx */
+	out += snprintf(db->buf + out, db->len - out,
+			"Number of Joins: %d  Joining Node: %d\n",
+			dlm->num_joins, dlm->joining_node);
+
+	/* Domain Map: xx xx xx */
+	out += snprintf(db->buf + out, db->len - out, "Domain Map: ");
+	out += stringify_nodemap(dlm->domain_map, O2NM_MAX_NODES,
+				 db->buf + out, db->len - out);
+	out += snprintf(db->buf + out, db->len - out, "\n");
+
+	/* Live Map: xx xx xx */
+	out += snprintf(db->buf + out, db->len - out, "Live Map: ");
+	out += stringify_nodemap(dlm->live_nodes_map, O2NM_MAX_NODES,
+				 db->buf + out, db->len - out);
+	out += snprintf(db->buf + out, db->len - out, "\n");
+
+	/* Mastered Resources Total: xxx  Locally: xxx  Remotely: ... */
+	out += snprintf(db->buf + out, db->len - out,
+			"Mastered Resources Total: %d  Locally: %d  "
+			"Remotely: %d  Unknown: %d\n",
+			tres, lres, rres, ures);
+
+	/* Lists: Dirty=Empty  Purge=InUse  PendingASTs=Empty  ... */
+	out += snprintf(db->buf + out, db->len - out,
+			"Lists: Dirty=%s  Purge=%s  PendingASTs=%s  "
+			"PendingBASTs=%s  Master=%s\n",
+			(list_empty(&dlm->dirty_list) ? "Empty" : "InUse"),
+			(list_empty(&dlm->purge_list) ? "Empty" : "InUse"),
+			(list_empty(&dlm->pending_asts) ? "Empty" : "InUse"),
+			(list_empty(&dlm->pending_basts) ? "Empty" : "InUse"),
+			(list_empty(&dlm->master_list) ? "Empty" : "InUse"));
+
+	/* Purge Count: xxx  Refs: xxx */
+	out += snprintf(db->buf + out, db->len - out,
+			"Purge Count: %d  Refs: %d\n", dlm->purge_count,
+			atomic_read(&dlm->dlm_refs.refcount));
+
+	/* Dead Node: xxx */
+	out += snprintf(db->buf + out, db->len - out,
+			"Dead Node: %d\n", dlm->reco.dead_node);
+
+	/* What about DLM_RECO_STATE_FINALIZE? */
+	if (dlm->reco.state == DLM_RECO_STATE_ACTIVE)
+		state = "ACTIVE";
+	else
+		state = "INACTIVE";
+
+	/* Recovery Pid: xxxx  Master: xxx  State: xxxx */
+	out += snprintf(db->buf + out, db->len - out,
+			"Recovery Pid: %d  Master: %d  State: %s\n",
+			dlm->dlm_reco_thread_task->pid,
+			dlm->reco.new_master, state);
+
+	/* Recovery Map: xx xx */
+	out += snprintf(db->buf + out, db->len - out, "Recovery Map: ");
+	out += stringify_nodemap(dlm->recovery_map, O2NM_MAX_NODES,
+				 db->buf + out, db->len - out);
+	out += snprintf(db->buf + out, db->len - out, "\n");
+
+	/* Recovery Node State: */
+	out += snprintf(db->buf + out, db->len - out, "Recovery Node State:\n");
+	list_for_each_entry(node, &dlm->reco.node_data, list) {
+		switch (node->state) {
+		case DLM_RECO_NODE_DATA_INIT:
+			state = "INIT";
+			break;
+		case DLM_RECO_NODE_DATA_REQUESTING:
+			state = "REQUESTING";
+			break;
+		case DLM_RECO_NODE_DATA_DEAD:
+			state = "DEAD";
+			break;
+		case DLM_RECO_NODE_DATA_RECEIVING:
+			state = "RECEIVING";
+			break;
+		case DLM_RECO_NODE_DATA_REQUESTED:
+			state = "REQUESTED";
+			break;
+		case DLM_RECO_NODE_DATA_DONE:
+			state = "DONE";
+			break;
+		case DLM_RECO_NODE_DATA_FINALIZE_SENT:
+			state = "FINALIZE-SENT";
+			break;
+		default:
+			state = "BAD";
+			break;
+		}
+		out += snprintf(db->buf + out, db->len - out, "\t%u - %s\n",
+				node->node_num, state);
+	}
+
+	spin_unlock(&dlm->spinlock);
+
+	return out;
+}
+
+static int debug_state_open(struct inode *inode, struct file *file)
+{
+	struct dlm_ctxt *dlm = inode->i_private;
+	struct debug_buffer *db = NULL;
+
+	db = debug_buffer_allocate();
+	if (!db)
+		goto bail;
+
+	db->len = debug_state_print(dlm, db);
+
+	file->private_data = db;
+
+	return 0;
+bail:
+	return -ENOMEM;
+}
+
+static struct file_operations debug_state_fops = {
+	.open =		debug_state_open,
+	.release =	debug_buffer_release,
+	.read =		debug_buffer_read,
+	.llseek =	debug_buffer_llseek,
+};
+/* end  - debug state funcs */
+
+/* files in subroot */
+int dlm_debug_init(struct dlm_ctxt *dlm)
+{
+	struct dlm_debug_ctxt *dc = dlm->dlm_debug_ctxt;
+
+	/* for dumping dlm_ctxt */
+	dc->debug_state_dentry = debugfs_create_file(DLM_DEBUGFS_DLM_STATE,
+						     S_IFREG|S_IRUSR,
+						     dlm->dlm_debugfs_subroot,
+						     dlm, &debug_state_fops);
+	if (!dc->debug_state_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	/* for dumping lockres */
+	dc->debug_lockres_dentry =
+			debugfs_create_file(DLM_DEBUGFS_LOCKING_STATE,
+					    S_IFREG|S_IRUSR,
+					    dlm->dlm_debugfs_subroot,
+					    dlm, &debug_lockres_fops);
+	if (!dc->debug_lockres_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	/* for dumping mles */
+	dc->debug_mle_dentry = debugfs_create_file(DLM_DEBUGFS_MLE_STATE,
+						   S_IFREG|S_IRUSR,
+						   dlm->dlm_debugfs_subroot,
+						   dlm, &debug_mle_fops);
+	if (!dc->debug_mle_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	/* for dumping lockres on the purge list */
+	dc->debug_purgelist_dentry =
+			debugfs_create_file(DLM_DEBUGFS_PURGE_LIST,
+					    S_IFREG|S_IRUSR,
+					    dlm->dlm_debugfs_subroot,
+					    dlm, &debug_purgelist_fops);
+	if (!dc->debug_purgelist_dentry) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	dlm_debug_get(dc);
+	return 0;
+
+bail:
+	dlm_debug_shutdown(dlm);
+	return -ENOMEM;
+}
+
+void dlm_debug_shutdown(struct dlm_ctxt *dlm)
+{
+	struct dlm_debug_ctxt *dc = dlm->dlm_debug_ctxt;
+
+	if (dc) {
+		if (dc->debug_purgelist_dentry)
+			debugfs_remove(dc->debug_purgelist_dentry);
+		if (dc->debug_mle_dentry)
+			debugfs_remove(dc->debug_mle_dentry);
+		if (dc->debug_lockres_dentry)
+			debugfs_remove(dc->debug_lockres_dentry);
+		if (dc->debug_state_dentry)
+			debugfs_remove(dc->debug_state_dentry);
+		dlm_debug_put(dc);
+	}
+}
+
+/* subroot - domain dir */
+int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+	dlm->dlm_debugfs_subroot = debugfs_create_dir(dlm->name,
+						      dlm_debugfs_root);
+	if (!dlm->dlm_debugfs_subroot) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+
+	dlm->dlm_debug_ctxt = kzalloc(sizeof(struct dlm_debug_ctxt),
+				      GFP_KERNEL);
+	if (!dlm->dlm_debug_ctxt) {
+		mlog_errno(-ENOMEM);
+		goto bail;
+	}
+	kref_init(&dlm->dlm_debug_ctxt->debug_refcnt);
+
+	return 0;
+bail:
+	dlm_destroy_debugfs_subroot(dlm);
+	return -ENOMEM;
+}
+
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+	if (dlm->dlm_debugfs_subroot)
+		debugfs_remove(dlm->dlm_debugfs_subroot);
+}
+
+/* debugfs root */
+int dlm_create_debugfs_root(void)
+{
+	dlm_debugfs_root = debugfs_create_dir(DLM_DEBUGFS_DIR, NULL);
+	if (!dlm_debugfs_root) {
+		mlog_errno(-ENOMEM);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+void dlm_destroy_debugfs_root(void)
+{
+	if (dlm_debugfs_root)
+		debugfs_remove(dlm_debugfs_root);
+}
+#endif	/* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/dlm/dlmdebug.h b/fs/ocfs2/dlm/dlmdebug.h
new file mode 100644
index 00000000000..d34a62a3a62
--- /dev/null
+++ b/fs/ocfs2/dlm/dlmdebug.h
@@ -0,0 +1,86 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dlmdebug.h
+ *
+ * Copyright (C) 2008 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 DLMDEBUG_H
+#define DLMDEBUG_H
+
+void dlm_print_one_mle(struct dlm_master_list_entry *mle);
+
+#ifdef CONFIG_DEBUG_FS
+
+struct dlm_debug_ctxt {
+	struct kref debug_refcnt;
+	struct dentry *debug_state_dentry;
+	struct dentry *debug_lockres_dentry;
+	struct dentry *debug_mle_dentry;
+	struct dentry *debug_purgelist_dentry;
+};
+
+struct debug_buffer {
+	int len;
+	char *buf;
+};
+
+struct debug_lockres {
+	int dl_len;
+	char *dl_buf;
+	struct dlm_ctxt *dl_ctxt;
+	struct dlm_lock_resource *dl_res;
+};
+
+int dlm_debug_init(struct dlm_ctxt *dlm);
+void dlm_debug_shutdown(struct dlm_ctxt *dlm);
+
+int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm);
+void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm);
+
+int dlm_create_debugfs_root(void);
+void dlm_destroy_debugfs_root(void);
+
+#else
+
+static int dlm_debug_init(struct dlm_ctxt *dlm)
+{
+	return 0;
+}
+static void dlm_debug_shutdown(struct dlm_ctxt *dlm)
+{
+}
+static int dlm_create_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+	return 0;
+}
+static void dlm_destroy_debugfs_subroot(struct dlm_ctxt *dlm)
+{
+}
+static int dlm_create_debugfs_root(void)
+{
+	return 0;
+}
+static void dlm_destroy_debugfs_root(void)
+{
+}
+
+#endif	/* CONFIG_DEBUG_FS */
+#endif	/* DLMDEBUG_H */
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 0879d86113e..63f8125824e 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -33,6 +33,7 @@
 #include <linux/spinlock.h>
 #include <linux/delay.h>
 #include <linux/err.h>
+#include <linux/debugfs.h>
 
 #include "cluster/heartbeat.h"
 #include "cluster/nodemanager.h"
@@ -40,8 +41,8 @@
 
 #include "dlmapi.h"
 #include "dlmcommon.h"
-
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #include "dlmver.h"
 
@@ -298,6 +299,8 @@ static int dlm_wait_on_domain_helper(const char *domain)
 
 static void dlm_free_ctxt_mem(struct dlm_ctxt *dlm)
 {
+	dlm_destroy_debugfs_subroot(dlm);
+
 	if (dlm->lockres_hash)
 		dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
 
@@ -395,6 +398,7 @@ static void dlm_destroy_dlm_worker(struct dlm_ctxt *dlm)
 static void dlm_complete_dlm_shutdown(struct dlm_ctxt *dlm)
 {
 	dlm_unregister_domain_handlers(dlm);
+	dlm_debug_shutdown(dlm);
 	dlm_complete_thread(dlm);
 	dlm_complete_recovery_thread(dlm);
 	dlm_destroy_dlm_worker(dlm);
@@ -644,6 +648,7 @@ int dlm_shutting_down(struct dlm_ctxt *dlm)
 void dlm_unregister_domain(struct dlm_ctxt *dlm)
 {
 	int leave = 0;
+	struct dlm_lock_resource *res;
 
 	spin_lock(&dlm_domain_lock);
 	BUG_ON(dlm->dlm_state != DLM_CTXT_JOINED);
@@ -673,6 +678,15 @@ void dlm_unregister_domain(struct dlm_ctxt *dlm)
 			msleep(500);
 			mlog(0, "%s: more migration to do\n", dlm->name);
 		}
+
+		/* This list should be empty. If not, print remaining lockres */
+		if (!list_empty(&dlm->tracking_list)) {
+			mlog(ML_ERROR, "Following lockres' are still on the "
+			     "tracking list:\n");
+			list_for_each_entry(res, &dlm->tracking_list, tracking)
+				dlm_print_one_lock_resource(res);
+		}
+
 		dlm_mark_domain_leaving(dlm);
 		dlm_leave_domain(dlm);
 		dlm_complete_dlm_shutdown(dlm);
@@ -1405,6 +1419,12 @@ static int dlm_join_domain(struct dlm_ctxt *dlm)
 		goto bail;
 	}
 
+	status = dlm_debug_init(dlm);
+	if (status < 0) {
+		mlog_errno(status);
+		goto bail;
+	}
+
 	status = dlm_launch_thread(dlm);
 	if (status < 0) {
 		mlog_errno(status);
@@ -1472,6 +1492,7 @@ bail:
 
 	if (status) {
 		dlm_unregister_domain_handlers(dlm);
+		dlm_debug_shutdown(dlm);
 		dlm_complete_thread(dlm);
 		dlm_complete_recovery_thread(dlm);
 		dlm_destroy_dlm_worker(dlm);
@@ -1484,6 +1505,7 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
 				u32 key)
 {
 	int i;
+	int ret;
 	struct dlm_ctxt *dlm = NULL;
 
 	dlm = kzalloc(sizeof(*dlm), GFP_KERNEL);
@@ -1516,6 +1538,15 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
 	dlm->key = key;
 	dlm->node_num = o2nm_this_node();
 
+	ret = dlm_create_debugfs_subroot(dlm);
+	if (ret < 0) {
+		dlm_free_pagevec((void **)dlm->lockres_hash, DLM_HASH_PAGES);
+		kfree(dlm->name);
+		kfree(dlm);
+		dlm = NULL;
+		goto leave;
+	}
+
 	spin_lock_init(&dlm->spinlock);
 	spin_lock_init(&dlm->master_lock);
 	spin_lock_init(&dlm->ast_lock);
@@ -1526,6 +1557,7 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
 	INIT_LIST_HEAD(&dlm->reco.node_data);
 	INIT_LIST_HEAD(&dlm->purge_list);
 	INIT_LIST_HEAD(&dlm->dlm_domain_handlers);
+	INIT_LIST_HEAD(&dlm->tracking_list);
 	dlm->reco.state = 0;
 
 	INIT_LIST_HEAD(&dlm->pending_asts);
@@ -1816,21 +1848,49 @@ static int __init dlm_init(void)
 	dlm_print_version();
 
 	status = dlm_init_mle_cache();
-	if (status)
-		return -1;
+	if (status) {
+		mlog(ML_ERROR, "Could not create o2dlm_mle slabcache\n");
+		goto error;
+	}
+
+	status = dlm_init_master_caches();
+	if (status) {
+		mlog(ML_ERROR, "Could not create o2dlm_lockres and "
+		     "o2dlm_lockname slabcaches\n");
+		goto error;
+	}
+
+	status = dlm_init_lock_cache();
+	if (status) {
+		mlog(ML_ERROR, "Count not create o2dlm_lock slabcache\n");
+		goto error;
+	}
 
 	status = dlm_register_net_handlers();
 	if (status) {
-		dlm_destroy_mle_cache();
-		return -1;
+		mlog(ML_ERROR, "Unable to register network handlers\n");
+		goto error;
 	}
 
+	status = dlm_create_debugfs_root();
+	if (status)
+		goto error;
+
 	return 0;
+error:
+	dlm_unregister_net_handlers();
+	dlm_destroy_lock_cache();
+	dlm_destroy_master_caches();
+	dlm_destroy_mle_cache();
+	return -1;
 }
 
 static void __exit dlm_exit (void)
 {
+	dlm_destroy_debugfs_root();
 	dlm_unregister_net_handlers();
+	dlm_destroy_lock_cache();
+	dlm_destroy_master_caches();
 	dlm_destroy_mle_cache();
 }
 
diff --git a/fs/ocfs2/dlm/dlmlock.c b/fs/ocfs2/dlm/dlmlock.c
index 52578d907d9..83a9f2972ac 100644
--- a/fs/ocfs2/dlm/dlmlock.c
+++ b/fs/ocfs2/dlm/dlmlock.c
@@ -53,6 +53,8 @@
 #define MLOG_MASK_PREFIX ML_DLM
 #include "cluster/masklog.h"
 
+static struct kmem_cache *dlm_lock_cache = NULL;
+
 static DEFINE_SPINLOCK(dlm_cookie_lock);
 static u64 dlm_next_cookie = 1;
 
@@ -64,6 +66,22 @@ static void dlm_init_lock(struct dlm_lock *newlock, int type,
 static void dlm_lock_release(struct kref *kref);
 static void dlm_lock_detach_lockres(struct dlm_lock *lock);
 
+int dlm_init_lock_cache(void)
+{
+	dlm_lock_cache = kmem_cache_create("o2dlm_lock",
+					   sizeof(struct dlm_lock),
+					   0, SLAB_HWCACHE_ALIGN, NULL);
+	if (dlm_lock_cache == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void dlm_destroy_lock_cache(void)
+{
+	if (dlm_lock_cache)
+		kmem_cache_destroy(dlm_lock_cache);
+}
+
 /* Tell us whether we can grant a new lock request.
  * locking:
  *   caller needs:  res->spinlock
@@ -353,7 +371,7 @@ static void dlm_lock_release(struct kref *kref)
 		mlog(0, "freeing kernel-allocated lksb\n");
 		kfree(lock->lksb);
 	}
-	kfree(lock);
+	kmem_cache_free(dlm_lock_cache, lock);
 }
 
 /* associate a lock with it's lockres, getting a ref on the lockres */
@@ -412,7 +430,7 @@ struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
 	struct dlm_lock *lock;
 	int kernel_allocated = 0;
 
-	lock = kzalloc(sizeof(*lock), GFP_NOFS);
+	lock = (struct dlm_lock *) kmem_cache_zalloc(dlm_lock_cache, GFP_NOFS);
 	if (!lock)
 		return NULL;
 
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index ea6b8957786..efc015c6128 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -48,47 +48,11 @@
 #include "dlmapi.h"
 #include "dlmcommon.h"
 #include "dlmdomain.h"
+#include "dlmdebug.h"
 
 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_MASTER)
 #include "cluster/masklog.h"
 
-enum dlm_mle_type {
-	DLM_MLE_BLOCK,
-	DLM_MLE_MASTER,
-	DLM_MLE_MIGRATION
-};
-
-struct dlm_lock_name
-{
-	u8 len;
-	u8 name[DLM_LOCKID_NAME_MAX];
-};
-
-struct dlm_master_list_entry
-{
-	struct list_head list;
-	struct list_head hb_events;
-	struct dlm_ctxt *dlm;
-	spinlock_t spinlock;
-	wait_queue_head_t wq;
-	atomic_t woken;
-	struct kref mle_refs;
-	int inuse;
-	unsigned long maybe_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-	unsigned long vote_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-	unsigned long response_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-	unsigned long node_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
-	u8 master;
-	u8 new_master;
-	enum dlm_mle_type type;
-	struct o2hb_callback_func mle_hb_up;
-	struct o2hb_callback_func mle_hb_down;
-	union {
-		struct dlm_lock_resource *res;
-		struct dlm_lock_name name;
-	} u;
-};
-
 static void dlm_mle_node_down(struct dlm_ctxt *dlm,
 			      struct dlm_master_list_entry *mle,
 			      struct o2nm_node *node,
@@ -128,98 +92,10 @@ static inline int dlm_mle_equal(struct dlm_ctxt *dlm,
 	return 1;
 }
 
-#define dlm_print_nodemap(m)  _dlm_print_nodemap(m,#m)
-static void _dlm_print_nodemap(unsigned long *map, const char *mapname)
-{
-	int i;
-	printk("%s=[ ", mapname);
-	for (i=0; i<O2NM_MAX_NODES; i++)
-		if (test_bit(i, map))
-			printk("%d ", i);
-	printk("]");
-}
-
-static void dlm_print_one_mle(struct dlm_master_list_entry *mle)
-{
-	int refs;
-	char *type;
-	char attached;
-	u8 master;
-	unsigned int namelen;
-	const char *name;
-	struct kref *k;
-	unsigned long *maybe = mle->maybe_map,
-		      *vote = mle->vote_map,
-		      *resp = mle->response_map,
-		      *node = mle->node_map;
-
-	k = &mle->mle_refs;
-	if (mle->type == DLM_MLE_BLOCK)
-		type = "BLK";
-	else if (mle->type == DLM_MLE_MASTER)
-		type = "MAS";
-	else
-		type = "MIG";
-	refs = atomic_read(&k->refcount);
-	master = mle->master;
-	attached = (list_empty(&mle->hb_events) ? 'N' : 'Y');
-
-	if (mle->type != DLM_MLE_MASTER) {
-		namelen = mle->u.name.len;
-		name = mle->u.name.name;
-	} else {
-		namelen = mle->u.res->lockname.len;
-		name = mle->u.res->lockname.name;
-	}
-
-	mlog(ML_NOTICE, "%.*s: %3s refs=%3d mas=%3u new=%3u evt=%c inuse=%d ",
-		  namelen, name, type, refs, master, mle->new_master, attached,
-		  mle->inuse);
-	dlm_print_nodemap(maybe);
-	printk(", ");
-	dlm_print_nodemap(vote);
-	printk(", ");
-	dlm_print_nodemap(resp);
-	printk(", ");
-	dlm_print_nodemap(node);
-	printk(", ");
-	printk("\n");
-}
-
-#if 0
-/* Code here is included but defined out as it aids debugging */
-
-static void dlm_dump_mles(struct dlm_ctxt *dlm)
-{
-	struct dlm_master_list_entry *mle;
-	
-	mlog(ML_NOTICE, "dumping all mles for domain %s:\n", dlm->name);
-	spin_lock(&dlm->master_lock);
-	list_for_each_entry(mle, &dlm->master_list, list)
-		dlm_print_one_mle(mle);
-	spin_unlock(&dlm->master_lock);
-}
-
-int dlm_dump_all_mles(const char __user *data, unsigned int len)
-{
-	struct dlm_ctxt *dlm;
-
-	spin_lock(&dlm_domain_lock);
-	list_for_each_entry(dlm, &dlm_domains, list) {
-		mlog(ML_NOTICE, "found dlm: %p, name=%s\n", dlm, dlm->name);
-		dlm_dump_mles(dlm);
-	}
-	spin_unlock(&dlm_domain_lock);
-	return len;
-}
-EXPORT_SYMBOL_GPL(dlm_dump_all_mles);
-
-#endif  /*  0  */
-
-
+static struct kmem_cache *dlm_lockres_cache = NULL;
+static struct kmem_cache *dlm_lockname_cache = NULL;
 static struct kmem_cache *dlm_mle_cache = NULL;
 
-
 static void dlm_mle_release(struct kref *kref);
 static void dlm_init_mle(struct dlm_master_list_entry *mle,
 			enum dlm_mle_type type,
@@ -507,7 +383,7 @@ static void dlm_mle_node_up(struct dlm_ctxt *dlm,
 
 int dlm_init_mle_cache(void)
 {
-	dlm_mle_cache = kmem_cache_create("dlm_mle_cache",
+	dlm_mle_cache = kmem_cache_create("o2dlm_mle",
 					  sizeof(struct dlm_master_list_entry),
 					  0, SLAB_HWCACHE_ALIGN,
 					  NULL);
@@ -560,6 +436,35 @@ static void dlm_mle_release(struct kref *kref)
  * LOCK RESOURCE FUNCTIONS
  */
 
+int dlm_init_master_caches(void)
+{
+	dlm_lockres_cache = kmem_cache_create("o2dlm_lockres",
+					      sizeof(struct dlm_lock_resource),
+					      0, SLAB_HWCACHE_ALIGN, NULL);
+	if (!dlm_lockres_cache)
+		goto bail;
+
+	dlm_lockname_cache = kmem_cache_create("o2dlm_lockname",
+					       DLM_LOCKID_NAME_MAX, 0,
+					       SLAB_HWCACHE_ALIGN, NULL);
+	if (!dlm_lockname_cache)
+		goto bail;
+
+	return 0;
+bail:
+	dlm_destroy_master_caches();
+	return -ENOMEM;
+}
+
+void dlm_destroy_master_caches(void)
+{
+	if (dlm_lockname_cache)
+		kmem_cache_destroy(dlm_lockname_cache);
+
+	if (dlm_lockres_cache)
+		kmem_cache_destroy(dlm_lockres_cache);
+}
+
 static void dlm_set_lockres_owner(struct dlm_ctxt *dlm,
 				  struct dlm_lock_resource *res,
 				  u8 owner)
@@ -610,6 +515,14 @@ static void dlm_lockres_release(struct kref *kref)
 	mlog(0, "destroying lockres %.*s\n", res->lockname.len,
 	     res->lockname.name);
 
+	if (!list_empty(&res->tracking))
+		list_del_init(&res->tracking);
+	else {
+		mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n",
+		     res->lockname.len, res->lockname.name);
+		dlm_print_one_lock_resource(res);
+	}
+
 	if (!hlist_unhashed(&res->hash_node) ||
 	    !list_empty(&res->granted) ||
 	    !list_empty(&res->converting) ||
@@ -642,9 +555,9 @@ static void dlm_lockres_release(struct kref *kref)
 	BUG_ON(!list_empty(&res->recovering));
 	BUG_ON(!list_empty(&res->purge));
 
-	kfree(res->lockname.name);
+	kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
 
-	kfree(res);
+	kmem_cache_free(dlm_lockres_cache, res);
 }
 
 void dlm_lockres_put(struct dlm_lock_resource *res)
@@ -677,6 +590,7 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
 	INIT_LIST_HEAD(&res->dirty);
 	INIT_LIST_HEAD(&res->recovering);
 	INIT_LIST_HEAD(&res->purge);
+	INIT_LIST_HEAD(&res->tracking);
 	atomic_set(&res->asts_reserved, 0);
 	res->migration_pending = 0;
 	res->inflight_locks = 0;
@@ -692,6 +606,8 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
 
 	res->last_used = 0;
 
+	list_add_tail(&res->tracking, &dlm->tracking_list);
+
 	memset(res->lvb, 0, DLM_LVB_LEN);
 	memset(res->refmap, 0, sizeof(res->refmap));
 }
@@ -700,20 +616,28 @@ struct dlm_lock_resource *dlm_new_lockres(struct dlm_ctxt *dlm,
 				   const char *name,
 				   unsigned int namelen)
 {
-	struct dlm_lock_resource *res;
+	struct dlm_lock_resource *res = NULL;
 
-	res = kmalloc(sizeof(struct dlm_lock_resource), GFP_NOFS);
+	res = (struct dlm_lock_resource *)
+				kmem_cache_zalloc(dlm_lockres_cache, GFP_NOFS);
 	if (!res)
-		return NULL;
+		goto error;
 
-	res->lockname.name = kmalloc(namelen, GFP_NOFS);
-	if (!res->lockname.name) {
-		kfree(res);
-		return NULL;
-	}
+	res->lockname.name = (char *)
+				kmem_cache_zalloc(dlm_lockname_cache, GFP_NOFS);
+	if (!res->lockname.name)
+		goto error;
 
 	dlm_init_lockres(dlm, res, name, namelen);
 	return res;
+
+error:
+	if (res && res->lockname.name)
+		kmem_cache_free(dlm_lockname_cache, (void *)res->lockname.name);
+
+	if (res)
+		kmem_cache_free(dlm_lockres_cache, res);
+	return NULL;
 }
 
 void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
diff --git a/fs/ocfs2/dlmglue.c b/fs/ocfs2/dlmglue.c
index 1f1873bf41f..394d25a131a 100644
--- a/fs/ocfs2/dlmglue.c
+++ b/fs/ocfs2/dlmglue.c
@@ -27,18 +27,11 @@
 #include <linux/slab.h>
 #include <linux/highmem.h>
 #include <linux/mm.h>
-#include <linux/crc32.h>
 #include <linux/kthread.h>
 #include <linux/pagemap.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 
-#include <cluster/heartbeat.h>
-#include <cluster/nodemanager.h>
-#include <cluster/tcp.h>
-
-#include <dlm/dlmapi.h>
-
 #define MLOG_MASK_PREFIX ML_DLM_GLUE
 #include <cluster/masklog.h>
 
@@ -53,6 +46,7 @@
 #include "heartbeat.h"
 #include "inode.h"
 #include "journal.h"
+#include "stackglue.h"
 #include "slot_map.h"
 #include "super.h"
 #include "uptodate.h"
@@ -113,7 +107,8 @@ static void ocfs2_dump_meta_lvb_info(u64 level,
 				     unsigned int line,
 				     struct ocfs2_lock_res *lockres)
 {
-	struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+	struct ocfs2_meta_lvb *lvb =
+		(struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
 	mlog(level, "LVB information for %s (called from %s:%u):\n",
 	     lockres->l_name, function, line);
@@ -259,31 +254,6 @@ static struct ocfs2_lock_res_ops ocfs2_flock_lops = {
 	.flags		= 0,
 };
 
-/*
- * This is the filesystem locking protocol version.
- *
- * Whenever the filesystem does new things with locks (adds or removes a
- * lock, orders them differently, does different things underneath a lock),
- * the version must be changed.  The protocol is negotiated when joining
- * the dlm domain.  A node may join the domain if its major version is
- * identical to all other nodes and its minor version is greater than
- * or equal to all other nodes.  When its minor version is greater than
- * the other nodes, it will run at the minor version specified by the
- * other nodes.
- *
- * If a locking change is made that will not be compatible with older
- * versions, the major number must be increased and the minor version set
- * to zero.  If a change merely adds a behavior that can be disabled when
- * speaking to older versions, the minor version must be increased.  If a
- * change adds a fully backwards compatible change (eg, LVB changes that
- * are just ignored by older versions), the version does not need to be
- * updated.
- */
-const struct dlm_protocol_version ocfs2_locking_protocol = {
-	.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
-	.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
-};
-
 static inline int ocfs2_is_inode_lock(struct ocfs2_lock_res *lockres)
 {
 	return lockres->l_type == OCFS2_LOCK_TYPE_META ||
@@ -316,7 +286,7 @@ static inline struct ocfs2_super *ocfs2_get_lockres_osb(struct ocfs2_lock_res *l
 static int ocfs2_lock_create(struct ocfs2_super *osb,
 			     struct ocfs2_lock_res *lockres,
 			     int level,
-			     int dlm_flags);
+			     u32 dlm_flags);
 static inline int ocfs2_may_continue_on_blocked_lock(struct ocfs2_lock_res *lockres,
 						     int wanted);
 static void ocfs2_cluster_unlock(struct ocfs2_super *osb,
@@ -330,10 +300,9 @@ static void ocfs2_schedule_blocked_lock(struct ocfs2_super *osb,
 					struct ocfs2_lock_res *lockres);
 static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
 						int convert);
-#define ocfs2_log_dlm_error(_func, _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));		\
+#define ocfs2_log_dlm_error(_func, _err, _lockres) do {			\
+	mlog(ML_ERROR, "DLM error %d while calling %s on resource %s\n", \
+	     _err, _func, _lockres->l_name);				\
 } while (0)
 static int ocfs2_downconvert_thread(void *arg);
 static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
@@ -342,12 +311,13 @@ static int ocfs2_inode_lock_update(struct inode *inode,
 				  struct buffer_head **bh);
 static void ocfs2_drop_osb_locks(struct ocfs2_super *osb);
 static inline int ocfs2_highest_compat_lock_level(int level);
-static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
-				      int new_level);
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+					      int new_level);
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
 				  struct ocfs2_lock_res *lockres,
 				  int new_level,
-				  int lvb);
+				  int lvb,
+				  unsigned int generation);
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
 				        struct ocfs2_lock_res *lockres);
 static int ocfs2_cancel_convert(struct ocfs2_super *osb,
@@ -406,9 +376,9 @@ static void ocfs2_lock_res_init_common(struct ocfs2_super *osb,
 	res->l_ops           = ops;
 	res->l_priv          = priv;
 
-	res->l_level         = LKM_IVMODE;
-	res->l_requested     = LKM_IVMODE;
-	res->l_blocking      = LKM_IVMODE;
+	res->l_level         = DLM_LOCK_IV;
+	res->l_requested     = DLM_LOCK_IV;
+	res->l_blocking      = DLM_LOCK_IV;
 	res->l_action        = OCFS2_AST_INVALID;
 	res->l_unlock_action = OCFS2_UNLOCK_INVALID;
 
@@ -604,10 +574,10 @@ static inline void ocfs2_inc_holders(struct ocfs2_lock_res *lockres,
 	BUG_ON(!lockres);
 
 	switch(level) {
-	case LKM_EXMODE:
+	case DLM_LOCK_EX:
 		lockres->l_ex_holders++;
 		break;
-	case LKM_PRMODE:
+	case DLM_LOCK_PR:
 		lockres->l_ro_holders++;
 		break;
 	default:
@@ -625,11 +595,11 @@ static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
 	BUG_ON(!lockres);
 
 	switch(level) {
-	case LKM_EXMODE:
+	case DLM_LOCK_EX:
 		BUG_ON(!lockres->l_ex_holders);
 		lockres->l_ex_holders--;
 		break;
-	case LKM_PRMODE:
+	case DLM_LOCK_PR:
 		BUG_ON(!lockres->l_ro_holders);
 		lockres->l_ro_holders--;
 		break;
@@ -644,12 +614,12 @@ static inline void ocfs2_dec_holders(struct ocfs2_lock_res *lockres,
  * lock types are added. */
 static inline int ocfs2_highest_compat_lock_level(int level)
 {
-	int new_level = LKM_EXMODE;
+	int new_level = DLM_LOCK_EX;
 
-	if (level == LKM_EXMODE)
-		new_level = LKM_NLMODE;
-	else if (level == LKM_PRMODE)
-		new_level = LKM_PRMODE;
+	if (level == DLM_LOCK_EX)
+		new_level = DLM_LOCK_NL;
+	else if (level == DLM_LOCK_PR)
+		new_level = DLM_LOCK_PR;
 	return new_level;
 }
 
@@ -688,12 +658,12 @@ static inline void ocfs2_generic_handle_downconvert_action(struct ocfs2_lock_res
 	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
 	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_ATTACHED));
 	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BLOCKED));
-	BUG_ON(lockres->l_blocking <= LKM_NLMODE);
+	BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
 	lockres->l_level = lockres->l_requested;
 	if (lockres->l_level <=
 	    ocfs2_highest_compat_lock_level(lockres->l_blocking)) {
-		lockres->l_blocking = LKM_NLMODE;
+		lockres->l_blocking = DLM_LOCK_NL;
 		lockres_clear_flags(lockres, OCFS2_LOCK_BLOCKED);
 	}
 	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
@@ -712,7 +682,7 @@ static inline void ocfs2_generic_handle_convert_action(struct ocfs2_lock_res *lo
 	 * information is already up to data. Convert from NL to
 	 * *anything* however should mark ourselves as needing an
 	 * update */
-	if (lockres->l_level == LKM_NLMODE &&
+	if (lockres->l_level == DLM_LOCK_NL &&
 	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
 		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
 
@@ -729,7 +699,7 @@ static inline void ocfs2_generic_handle_attach_action(struct ocfs2_lock_res *loc
 	BUG_ON((!(lockres->l_flags & OCFS2_LOCK_BUSY)));
 	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
 
-	if (lockres->l_requested > LKM_NLMODE &&
+	if (lockres->l_requested > DLM_LOCK_NL &&
 	    !(lockres->l_flags & OCFS2_LOCK_LOCAL) &&
 	    lockres->l_ops->flags & LOCK_TYPE_REQUIRES_REFRESH)
 		lockres_or_flags(lockres, OCFS2_LOCK_NEEDS_REFRESH);
@@ -767,6 +737,113 @@ static int ocfs2_generic_handle_bast(struct ocfs2_lock_res *lockres,
 	return needs_downconvert;
 }
 
+/*
+ * OCFS2_LOCK_PENDING and l_pending_gen.
+ *
+ * Why does OCFS2_LOCK_PENDING exist?  To close a race between setting
+ * OCFS2_LOCK_BUSY and calling ocfs2_dlm_lock().  See ocfs2_unblock_lock()
+ * for more details on the race.
+ *
+ * OCFS2_LOCK_PENDING closes the race quite nicely.  However, it introduces
+ * a race on itself.  In o2dlm, we can get the ast before ocfs2_dlm_lock()
+ * returns.  The ast clears OCFS2_LOCK_BUSY, and must therefore clear
+ * OCFS2_LOCK_PENDING at the same time.  When ocfs2_dlm_lock() returns,
+ * the caller is going to try to clear PENDING again.  If nothing else is
+ * happening, __lockres_clear_pending() sees PENDING is unset and does
+ * nothing.
+ *
+ * But what if another path (eg downconvert thread) has just started a
+ * new locking action?  The other path has re-set PENDING.  Our path
+ * cannot clear PENDING, because that will re-open the original race
+ * window.
+ *
+ * [Example]
+ *
+ * ocfs2_meta_lock()
+ *  ocfs2_cluster_lock()
+ *   set BUSY
+ *   set PENDING
+ *   drop l_lock
+ *   ocfs2_dlm_lock()
+ *    ocfs2_locking_ast()		ocfs2_downconvert_thread()
+ *     clear PENDING			 ocfs2_unblock_lock()
+ *					  take_l_lock
+ *					  !BUSY
+ *					  ocfs2_prepare_downconvert()
+ *					   set BUSY
+ *					   set PENDING
+ *					  drop l_lock
+ *   take l_lock
+ *   clear PENDING
+ *   drop l_lock
+ *			<window>
+ *					  ocfs2_dlm_lock()
+ *
+ * So as you can see, we now have a window where l_lock is not held,
+ * PENDING is not set, and ocfs2_dlm_lock() has not been called.
+ *
+ * The core problem is that ocfs2_cluster_lock() has cleared the PENDING
+ * set by ocfs2_prepare_downconvert().  That wasn't nice.
+ *
+ * To solve this we introduce l_pending_gen.  A call to
+ * lockres_clear_pending() will only do so when it is passed a generation
+ * number that matches the lockres.  lockres_set_pending() will return the
+ * current generation number.  When ocfs2_cluster_lock() goes to clear
+ * PENDING, it passes the generation it got from set_pending().  In our
+ * example above, the generation numbers will *not* match.  Thus,
+ * ocfs2_cluster_lock() will not clear the PENDING set by
+ * ocfs2_prepare_downconvert().
+ */
+
+/* Unlocked version for ocfs2_locking_ast() */
+static void __lockres_clear_pending(struct ocfs2_lock_res *lockres,
+				    unsigned int generation,
+				    struct ocfs2_super *osb)
+{
+	assert_spin_locked(&lockres->l_lock);
+
+	/*
+	 * The ast and locking functions can race us here.  The winner
+	 * will clear pending, the loser will not.
+	 */
+	if (!(lockres->l_flags & OCFS2_LOCK_PENDING) ||
+	    (lockres->l_pending_gen != generation))
+		return;
+
+	lockres_clear_flags(lockres, OCFS2_LOCK_PENDING);
+	lockres->l_pending_gen++;
+
+	/*
+	 * The downconvert thread may have skipped us because we
+	 * were PENDING.  Wake it up.
+	 */
+	if (lockres->l_flags & OCFS2_LOCK_BLOCKED)
+		ocfs2_wake_downconvert_thread(osb);
+}
+
+/* Locked version for callers of ocfs2_dlm_lock() */
+static void lockres_clear_pending(struct ocfs2_lock_res *lockres,
+				  unsigned int generation,
+				  struct ocfs2_super *osb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lockres->l_lock, flags);
+	__lockres_clear_pending(lockres, generation, osb);
+	spin_unlock_irqrestore(&lockres->l_lock, flags);
+}
+
+static unsigned int lockres_set_pending(struct ocfs2_lock_res *lockres)
+{
+	assert_spin_locked(&lockres->l_lock);
+	BUG_ON(!(lockres->l_flags & OCFS2_LOCK_BUSY));
+
+	lockres_or_flags(lockres, OCFS2_LOCK_PENDING);
+
+	return lockres->l_pending_gen;
+}
+
+
 static void ocfs2_blocking_ast(void *opaque, int level)
 {
 	struct ocfs2_lock_res *lockres = opaque;
@@ -774,7 +851,7 @@ static void ocfs2_blocking_ast(void *opaque, int level)
 	int needs_downconvert;
 	unsigned long flags;
 
-	BUG_ON(level <= LKM_NLMODE);
+	BUG_ON(level <= DLM_LOCK_NL);
 
 	mlog(0, "BAST fired for lockres %s, blocking %d, level %d type %s\n",
 	     lockres->l_name, level, lockres->l_level,
@@ -801,14 +878,22 @@ static void ocfs2_blocking_ast(void *opaque, int level)
 static void ocfs2_locking_ast(void *opaque)
 {
 	struct ocfs2_lock_res *lockres = opaque;
-	struct dlm_lockstatus *lksb = &lockres->l_lksb;
+	struct ocfs2_super *osb = ocfs2_get_lockres_osb(lockres);
 	unsigned long flags;
+	int status;
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
 
-	if (lksb->status != DLM_NORMAL) {
-		mlog(ML_ERROR, "lockres %s: lksb status value of %u!\n",
-		     lockres->l_name, lksb->status);
+	status = ocfs2_dlm_lock_status(&lockres->l_lksb);
+
+	if (status == -EAGAIN) {
+		lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
+		goto out;
+	}
+
+	if (status) {
+		mlog(ML_ERROR, "lockres %s: lksb status value of %d!\n",
+		     lockres->l_name, status);
 		spin_unlock_irqrestore(&lockres->l_lock, flags);
 		return;
 	}
@@ -831,11 +916,23 @@ static void ocfs2_locking_ast(void *opaque)
 		     lockres->l_unlock_action);
 		BUG();
 	}
-
+out:
 	/* set it to something invalid so if we get called again we
 	 * can catch it. */
 	lockres->l_action = OCFS2_AST_INVALID;
 
+	/* Did we try to cancel this lock?  Clear that state */
+	if (lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT)
+		lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
+
+	/*
+	 * We may have beaten the locking functions here.  We certainly
+	 * know that dlm_lock() has been called :-)
+	 * Because we can't have two lock calls in flight at once, we
+	 * can use lockres->l_pending_gen.
+	 */
+	__lockres_clear_pending(lockres, lockres->l_pending_gen,  osb);
+
 	wake_up(&lockres->l_event);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 }
@@ -865,15 +962,15 @@ static inline void ocfs2_recover_from_dlm_error(struct ocfs2_lock_res *lockres,
 static int ocfs2_lock_create(struct ocfs2_super *osb,
 			     struct ocfs2_lock_res *lockres,
 			     int level,
-			     int dlm_flags)
+			     u32 dlm_flags)
 {
 	int ret = 0;
-	enum dlm_status status = DLM_NORMAL;
 	unsigned long flags;
+	unsigned int gen;
 
 	mlog_entry_void();
 
-	mlog(0, "lock %s, level = %d, flags = %d\n", lockres->l_name, level,
+	mlog(0, "lock %s, level = %d, flags = %u\n", lockres->l_name, level,
 	     dlm_flags);
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
@@ -886,24 +983,23 @@ static int ocfs2_lock_create(struct ocfs2_super *osb,
 	lockres->l_action = OCFS2_AST_ATTACH;
 	lockres->l_requested = level;
 	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+	gen = lockres_set_pending(lockres);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-	status = dlmlock(osb->dlm,
-			 level,
-			 &lockres->l_lksb,
-			 dlm_flags,
-			 lockres->l_name,
-			 OCFS2_LOCK_ID_MAX_LEN - 1,
-			 ocfs2_locking_ast,
-			 lockres,
-			 ocfs2_blocking_ast);
-	if (status != DLM_NORMAL) {
-		ocfs2_log_dlm_error("dlmlock", status, lockres);
-		ret = -EINVAL;
+	ret = ocfs2_dlm_lock(osb->cconn,
+			     level,
+			     &lockres->l_lksb,
+			     dlm_flags,
+			     lockres->l_name,
+			     OCFS2_LOCK_ID_MAX_LEN - 1,
+			     lockres);
+	lockres_clear_pending(lockres, gen, osb);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
 		ocfs2_recover_from_dlm_error(lockres, 1);
 	}
 
-	mlog(0, "lock %s, successfull return from dlmlock\n", lockres->l_name);
+	mlog(0, "lock %s, return from ocfs2_dlm_lock\n", lockres->l_name);
 
 bail:
 	mlog_exit(ret);
@@ -1016,21 +1112,22 @@ static int ocfs2_wait_for_mask_interruptible(struct ocfs2_mask_waiter *mw,
 static int ocfs2_cluster_lock(struct ocfs2_super *osb,
 			      struct ocfs2_lock_res *lockres,
 			      int level,
-			      int lkm_flags,
+			      u32 lkm_flags,
 			      int arg_flags)
 {
 	struct ocfs2_mask_waiter mw;
-	enum dlm_status status;
 	int wait, catch_signals = !(osb->s_mount_opt & OCFS2_MOUNT_NOINTR);
 	int ret = 0; /* gcc doesn't realize wait = 1 guarantees ret is set */
 	unsigned long flags;
+	unsigned int gen;
+	int noqueue_attempted = 0;
 
 	mlog_entry_void();
 
 	ocfs2_init_mask_waiter(&mw);
 
 	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
-		lkm_flags |= LKM_VALBLK;
+		lkm_flags |= DLM_LKF_VALBLK;
 
 again:
 	wait = 0;
@@ -1068,52 +1165,56 @@ again:
 	}
 
 	if (level > lockres->l_level) {
+		if (noqueue_attempted > 0) {
+			ret = -EAGAIN;
+			goto unlock;
+		}
+		if (lkm_flags & DLM_LKF_NOQUEUE)
+			noqueue_attempted = 1;
+
 		if (lockres->l_action != OCFS2_AST_INVALID)
 			mlog(ML_ERROR, "lockres %s has action %u pending\n",
 			     lockres->l_name, lockres->l_action);
 
 		if (!(lockres->l_flags & OCFS2_LOCK_ATTACHED)) {
 			lockres->l_action = OCFS2_AST_ATTACH;
-			lkm_flags &= ~LKM_CONVERT;
+			lkm_flags &= ~DLM_LKF_CONVERT;
 		} else {
 			lockres->l_action = OCFS2_AST_CONVERT;
-			lkm_flags |= LKM_CONVERT;
+			lkm_flags |= DLM_LKF_CONVERT;
 		}
 
 		lockres->l_requested = level;
 		lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+		gen = lockres_set_pending(lockres);
 		spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-		BUG_ON(level == LKM_IVMODE);
-		BUG_ON(level == LKM_NLMODE);
+		BUG_ON(level == DLM_LOCK_IV);
+		BUG_ON(level == DLM_LOCK_NL);
 
 		mlog(0, "lock %s, convert from %d to level = %d\n",
 		     lockres->l_name, lockres->l_level, level);
 
 		/* call dlm_lock to upgrade lock now */
-		status = dlmlock(osb->dlm,
-				 level,
-				 &lockres->l_lksb,
-				 lkm_flags,
-				 lockres->l_name,
-				 OCFS2_LOCK_ID_MAX_LEN - 1,
-				 ocfs2_locking_ast,
-				 lockres,
-				 ocfs2_blocking_ast);
-		if (status != DLM_NORMAL) {
-			if ((lkm_flags & LKM_NOQUEUE) &&
-			    (status == DLM_NOTQUEUED))
-				ret = -EAGAIN;
-			else {
-				ocfs2_log_dlm_error("dlmlock", status,
-						    lockres);
-				ret = -EINVAL;
+		ret = ocfs2_dlm_lock(osb->cconn,
+				     level,
+				     &lockres->l_lksb,
+				     lkm_flags,
+				     lockres->l_name,
+				     OCFS2_LOCK_ID_MAX_LEN - 1,
+				     lockres);
+		lockres_clear_pending(lockres, gen, osb);
+		if (ret) {
+			if (!(lkm_flags & DLM_LKF_NOQUEUE) ||
+			    (ret != -EAGAIN)) {
+				ocfs2_log_dlm_error("ocfs2_dlm_lock",
+						    ret, lockres);
 			}
 			ocfs2_recover_from_dlm_error(lockres, 1);
 			goto out;
 		}
 
-		mlog(0, "lock %s, successfull return from dlmlock\n",
+		mlog(0, "lock %s, successfull return from ocfs2_dlm_lock\n",
 		     lockres->l_name);
 
 		/* At this point we've gone inside the dlm and need to
@@ -1177,9 +1278,9 @@ static int ocfs2_create_new_lock(struct ocfs2_super *osb,
 				 int ex,
 				 int local)
 {
-	int level =  ex ? LKM_EXMODE : LKM_PRMODE;
+	int level =  ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	unsigned long flags;
-	int lkm_flags = local ? LKM_LOCAL : 0;
+	u32 lkm_flags = local ? DLM_LKF_LOCAL : 0;
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
 	BUG_ON(lockres->l_flags & OCFS2_LOCK_ATTACHED);
@@ -1222,7 +1323,7 @@ int ocfs2_create_new_inode_locks(struct inode *inode)
 	}
 
 	/*
-	 * We don't want to use LKM_LOCAL on a meta data lock as they
+	 * We don't want to use DLM_LKF_LOCAL on a meta data lock as they
 	 * don't use a generation in their lock names.
 	 */
 	ret = ocfs2_create_new_lock(osb, &OCFS2_I(inode)->ip_inode_lockres, 1, 0);
@@ -1261,7 +1362,7 @@ int ocfs2_rw_lock(struct inode *inode, int write)
 
 	lockres = &OCFS2_I(inode)->ip_rw_lockres;
 
-	level = write ? LKM_EXMODE : LKM_PRMODE;
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 
 	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres, level, 0,
 				    0);
@@ -1274,7 +1375,7 @@ int ocfs2_rw_lock(struct inode *inode, int write)
 
 void ocfs2_rw_unlock(struct inode *inode, int write)
 {
-	int level = write ? LKM_EXMODE : LKM_PRMODE;
+	int level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_rw_lockres;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
@@ -1312,7 +1413,7 @@ int ocfs2_open_lock(struct inode *inode)
 	lockres = &OCFS2_I(inode)->ip_open_lockres;
 
 	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,
-				    LKM_PRMODE, 0, 0);
+				    DLM_LOCK_PR, 0, 0);
 	if (status < 0)
 		mlog_errno(status);
 
@@ -1340,16 +1441,16 @@ int ocfs2_try_open_lock(struct inode *inode, int write)
 
 	lockres = &OCFS2_I(inode)->ip_open_lockres;
 
-	level = write ? LKM_EXMODE : LKM_PRMODE;
+	level = write ? DLM_LOCK_EX : DLM_LOCK_PR;
 
 	/*
 	 * The file system may already holding a PRMODE/EXMODE open lock.
-	 * Since we pass LKM_NOQUEUE, the request won't block waiting on
+	 * Since we pass DLM_LKF_NOQUEUE, the request won't block waiting on
 	 * other nodes and the -EAGAIN will indicate to the caller that
 	 * this inode is still in use.
 	 */
 	status = ocfs2_cluster_lock(OCFS2_SB(inode->i_sb), lockres,
-				    level, LKM_NOQUEUE, 0);
+				    level, DLM_LKF_NOQUEUE, 0);
 
 out:
 	mlog_exit(status);
@@ -1374,10 +1475,10 @@ void ocfs2_open_unlock(struct inode *inode)
 
 	if(lockres->l_ro_holders)
 		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,
-				     LKM_PRMODE);
+				     DLM_LOCK_PR);
 	if(lockres->l_ex_holders)
 		ocfs2_cluster_unlock(OCFS2_SB(inode->i_sb), lockres,
-				     LKM_EXMODE);
+				     DLM_LOCK_EX);
 
 out:
 	mlog_exit_void();
@@ -1464,7 +1565,7 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
 	ocfs2_init_mask_waiter(&mw);
 
 	if ((lockres->l_flags & OCFS2_LOCK_BUSY) ||
-	    (lockres->l_level > LKM_NLMODE)) {
+	    (lockres->l_level > DLM_LOCK_NL)) {
 		mlog(ML_ERROR,
 		     "File lock \"%s\" has busy or locked state: flags: 0x%lx, "
 		     "level: %u\n", lockres->l_name, lockres->l_flags,
@@ -1503,14 +1604,12 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
 	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-	ret = dlmlock(osb->dlm, level, &lockres->l_lksb, lkm_flags,
-		      lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1,
-		      ocfs2_locking_ast, lockres, ocfs2_blocking_ast);
-	if (ret != DLM_NORMAL) {
-		if (trylock && ret == DLM_NOTQUEUED)
-			ret = -EAGAIN;
-		else {
-			ocfs2_log_dlm_error("dlmlock", ret, lockres);
+	ret = ocfs2_dlm_lock(osb->cconn, level, &lockres->l_lksb, lkm_flags,
+			     lockres->l_name, OCFS2_LOCK_ID_MAX_LEN - 1,
+			     lockres);
+	if (ret) {
+		if (!trylock || (ret != -EAGAIN)) {
+			ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
 			ret = -EINVAL;
 		}
 
@@ -1537,6 +1636,10 @@ int ocfs2_file_lock(struct file *file, int ex, int trylock)
 		 * to just bubble sucess back up to the user.
 		 */
 		ret = ocfs2_flock_handle_signal(lockres, level);
+	} else if (!ret && (level > lockres->l_level)) {
+		/* Trylock failed asynchronously */
+		BUG_ON(!trylock);
+		ret = -EAGAIN;
 	}
 
 out:
@@ -1549,6 +1652,7 @@ out:
 void ocfs2_file_unlock(struct file *file)
 {
 	int ret;
+	unsigned int gen;
 	unsigned long flags;
 	struct ocfs2_file_private *fp = file->private_data;
 	struct ocfs2_lock_res *lockres = &fp->fp_flock;
@@ -1572,13 +1676,13 @@ void ocfs2_file_unlock(struct file *file)
 	 * Fake a blocking ast for the downconvert code.
 	 */
 	lockres_or_flags(lockres, OCFS2_LOCK_BLOCKED);
-	lockres->l_blocking = LKM_EXMODE;
+	lockres->l_blocking = DLM_LOCK_EX;
 
-	ocfs2_prepare_downconvert(lockres, LKM_NLMODE);
+	gen = ocfs2_prepare_downconvert(lockres, LKM_NLMODE);
 	lockres_add_mask_waiter(lockres, &mw, OCFS2_LOCK_BUSY, 0);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 
-	ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0);
+	ret = ocfs2_downconvert_lock(osb, lockres, LKM_NLMODE, 0, gen);
 	if (ret) {
 		mlog_errno(ret);
 		return;
@@ -1601,11 +1705,11 @@ static void ocfs2_downconvert_on_unlock(struct ocfs2_super *osb,
 	 * condition. */
 	if (lockres->l_flags & OCFS2_LOCK_BLOCKED) {
 		switch(lockres->l_blocking) {
-		case LKM_EXMODE:
+		case DLM_LOCK_EX:
 			if (!lockres->l_ex_holders && !lockres->l_ro_holders)
 				kick = 1;
 			break;
-		case LKM_PRMODE:
+		case DLM_LOCK_PR:
 			if (!lockres->l_ex_holders)
 				kick = 1;
 			break;
@@ -1648,7 +1752,7 @@ static void __ocfs2_stuff_meta_lvb(struct inode *inode)
 
 	mlog_entry_void();
 
-	lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+	lvb = (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
 	/*
 	 * Invalidate the LVB of a deleted inode - this way other
@@ -1700,7 +1804,7 @@ static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
 
 	mlog_meta_lvb(0, lockres);
 
-	lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+	lvb = (struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
 	/* We're safe here without the lockres lock... */
 	spin_lock(&oi->ip_lock);
@@ -1735,7 +1839,8 @@ static void ocfs2_refresh_inode_from_lvb(struct inode *inode)
 static inline int ocfs2_meta_lvb_is_trustable(struct inode *inode,
 					      struct ocfs2_lock_res *lockres)
 {
-	struct ocfs2_meta_lvb *lvb = (struct ocfs2_meta_lvb *) lockres->l_lksb.lvb;
+	struct ocfs2_meta_lvb *lvb =
+		(struct ocfs2_meta_lvb *)ocfs2_dlm_lvb(&lockres->l_lksb);
 
 	if (lvb->lvb_version == OCFS2_LVB_VERSION
 	    && be32_to_cpu(lvb->lvb_igeneration) == inode->i_generation)
@@ -1923,7 +2028,8 @@ int ocfs2_inode_lock_full(struct inode *inode,
 			 int ex,
 			 int arg_flags)
 {
-	int status, level, dlm_flags, acquired;
+	int status, level, acquired;
+	u32 dlm_flags;
 	struct ocfs2_lock_res *lockres = NULL;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 	struct buffer_head *local_bh = NULL;
@@ -1950,14 +2056,13 @@ int ocfs2_inode_lock_full(struct inode *inode,
 		goto local;
 
 	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
-		wait_event(osb->recovery_event,
-			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));
+		ocfs2_wait_for_recovery(osb);
 
 	lockres = &OCFS2_I(inode)->ip_inode_lockres;
-	level = ex ? LKM_EXMODE : LKM_PRMODE;
+	level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	dlm_flags = 0;
 	if (arg_flags & OCFS2_META_LOCK_NOQUEUE)
-		dlm_flags |= LKM_NOQUEUE;
+		dlm_flags |= DLM_LKF_NOQUEUE;
 
 	status = ocfs2_cluster_lock(osb, lockres, level, dlm_flags, arg_flags);
 	if (status < 0) {
@@ -1974,8 +2079,7 @@ int ocfs2_inode_lock_full(struct inode *inode,
 	 * committed to owning this lock so we don't allow signals to
 	 * abort the operation. */
 	if (!(arg_flags & OCFS2_META_LOCK_RECOVERY))
-		wait_event(osb->recovery_event,
-			   ocfs2_node_map_is_empty(osb, &osb->recovery_map));
+		ocfs2_wait_for_recovery(osb);
 
 local:
 	/*
@@ -2109,7 +2213,7 @@ int ocfs2_inode_lock_atime(struct inode *inode,
 void ocfs2_inode_unlock(struct inode *inode,
 		       int ex)
 {
-	int level = ex ? LKM_EXMODE : LKM_PRMODE;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_lock_res *lockres = &OCFS2_I(inode)->ip_inode_lockres;
 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
 
@@ -2130,10 +2234,8 @@ int ocfs2_super_lock(struct ocfs2_super *osb,
 		     int ex)
 {
 	int status = 0;
-	int level = ex ? LKM_EXMODE : LKM_PRMODE;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
-	struct buffer_head *bh;
-	struct ocfs2_slot_info *si = osb->slot_info;
 
 	mlog_entry_void();
 
@@ -2159,11 +2261,7 @@ int ocfs2_super_lock(struct ocfs2_super *osb,
 		goto bail;
 	}
 	if (status) {
-		bh = si->si_bh;
-		status = ocfs2_read_block(osb, bh->b_blocknr, &bh, 0,
-					  si->si_inode);
-		if (status == 0)
-			ocfs2_update_slot_info(si);
+		status = ocfs2_refresh_slot_info(osb);
 
 		ocfs2_complete_lock_res_refresh(lockres, status);
 
@@ -2178,7 +2276,7 @@ bail:
 void ocfs2_super_unlock(struct ocfs2_super *osb,
 			int ex)
 {
-	int level = ex ? LKM_EXMODE : LKM_PRMODE;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_lock_res *lockres = &osb->osb_super_lockres;
 
 	if (!ocfs2_mount_local(osb))
@@ -2196,7 +2294,7 @@ int ocfs2_rename_lock(struct ocfs2_super *osb)
 	if (ocfs2_mount_local(osb))
 		return 0;
 
-	status = ocfs2_cluster_lock(osb, lockres, LKM_EXMODE, 0, 0);
+	status = ocfs2_cluster_lock(osb, lockres, DLM_LOCK_EX, 0, 0);
 	if (status < 0)
 		mlog_errno(status);
 
@@ -2208,13 +2306,13 @@ void ocfs2_rename_unlock(struct ocfs2_super *osb)
 	struct ocfs2_lock_res *lockres = &osb->osb_rename_lockres;
 
 	if (!ocfs2_mount_local(osb))
-		ocfs2_cluster_unlock(osb, lockres, LKM_EXMODE);
+		ocfs2_cluster_unlock(osb, lockres, DLM_LOCK_EX);
 }
 
 int ocfs2_dentry_lock(struct dentry *dentry, int ex)
 {
 	int ret;
-	int level = ex ? LKM_EXMODE : LKM_PRMODE;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
 	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
@@ -2235,7 +2333,7 @@ int ocfs2_dentry_lock(struct dentry *dentry, int ex)
 
 void ocfs2_dentry_unlock(struct dentry *dentry, int ex)
 {
-	int level = ex ? LKM_EXMODE : LKM_PRMODE;
+	int level = ex ? DLM_LOCK_EX : DLM_LOCK_PR;
 	struct ocfs2_dentry_lock *dl = dentry->d_fsdata;
 	struct ocfs2_super *osb = OCFS2_SB(dentry->d_sb);
 
@@ -2400,7 +2498,7 @@ static int ocfs2_dlm_seq_show(struct seq_file *m, void *v)
 		   lockres->l_blocking);
 
 	/* Dump the raw LVB */
-	lvb = lockres->l_lksb.lvb;
+	lvb = ocfs2_dlm_lvb(&lockres->l_lksb);
 	for(i = 0; i < DLM_LVB_LEN; i++)
 		seq_printf(m, "0x%x\t", lvb[i]);
 
@@ -2504,13 +2602,14 @@ static void ocfs2_dlm_shutdown_debug(struct ocfs2_super *osb)
 int ocfs2_dlm_init(struct ocfs2_super *osb)
 {
 	int status = 0;
-	u32 dlm_key;
-	struct dlm_ctxt *dlm = NULL;
+	struct ocfs2_cluster_connection *conn = NULL;
 
 	mlog_entry_void();
 
-	if (ocfs2_mount_local(osb))
+	if (ocfs2_mount_local(osb)) {
+		osb->node_num = 0;
 		goto local;
+	}
 
 	status = ocfs2_dlm_init_debug(osb);
 	if (status < 0) {
@@ -2527,26 +2626,31 @@ int ocfs2_dlm_init(struct ocfs2_super *osb)
 		goto bail;
 	}
 
-	/* used by the dlm code to make message headers unique, each
-	 * node in this domain must agree on this. */
-	dlm_key = crc32_le(0, osb->uuid_str, strlen(osb->uuid_str));
-
 	/* for now, uuid == domain */
-	dlm = dlm_register_domain(osb->uuid_str, dlm_key,
-				  &osb->osb_locking_proto);
-	if (IS_ERR(dlm)) {
-		status = PTR_ERR(dlm);
+	status = ocfs2_cluster_connect(osb->osb_cluster_stack,
+				       osb->uuid_str,
+				       strlen(osb->uuid_str),
+				       ocfs2_do_node_down, osb,
+				       &conn);
+	if (status) {
 		mlog_errno(status);
 		goto bail;
 	}
 
-	dlm_register_eviction_cb(dlm, &osb->osb_eviction_cb);
+	status = ocfs2_cluster_this_node(&osb->node_num);
+	if (status < 0) {
+		mlog_errno(status);
+		mlog(ML_ERROR,
+		     "could not find this host's node number\n");
+		ocfs2_cluster_disconnect(conn, 0);
+		goto bail;
+	}
 
 local:
 	ocfs2_super_lock_res_init(&osb->osb_super_lockres, osb);
 	ocfs2_rename_lock_res_init(&osb->osb_rename_lockres, osb);
 
-	osb->dlm = dlm;
+	osb->cconn = conn;
 
 	status = 0;
 bail:
@@ -2560,14 +2664,19 @@ bail:
 	return status;
 }
 
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb,
+			int hangup_pending)
 {
 	mlog_entry_void();
 
-	dlm_unregister_eviction_cb(&osb->osb_eviction_cb);
-
 	ocfs2_drop_osb_locks(osb);
 
+	/*
+	 * Now that we have dropped all locks and ocfs2_dismount_volume()
+	 * has disabled recovery, the DLM won't be talking to us.  It's
+	 * safe to tear things down before disconnecting the cluster.
+	 */
+
 	if (osb->dc_task) {
 		kthread_stop(osb->dc_task);
 		osb->dc_task = NULL;
@@ -2576,15 +2685,15 @@ void ocfs2_dlm_shutdown(struct ocfs2_super *osb)
 	ocfs2_lock_res_free(&osb->osb_super_lockres);
 	ocfs2_lock_res_free(&osb->osb_rename_lockres);
 
-	dlm_unregister_domain(osb->dlm);
-	osb->dlm = NULL;
+	ocfs2_cluster_disconnect(osb->cconn, hangup_pending);
+	osb->cconn = NULL;
 
 	ocfs2_dlm_shutdown_debug(osb);
 
 	mlog_exit_void();
 }
 
-static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
+static void ocfs2_unlock_ast(void *opaque, int error)
 {
 	struct ocfs2_lock_res *lockres = opaque;
 	unsigned long flags;
@@ -2595,24 +2704,9 @@ static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
 	     lockres->l_unlock_action);
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
-	/* We tried to cancel a convert request, but it was already
-	 * granted. All we want to do here is clear our unlock
-	 * state. The wake_up call done at the bottom is redundant
-	 * (ocfs2_prepare_cancel_convert doesn't sleep on this) but doesn't
-	 * hurt anything anyway */
-	if (status == DLM_CANCELGRANT &&
-	    lockres->l_unlock_action == OCFS2_UNLOCK_CANCEL_CONVERT) {
-		mlog(0, "Got cancelgrant for %s\n", lockres->l_name);
-
-		/* We don't clear the busy flag in this case as it
-		 * should have been cleared by the ast which the dlm
-		 * has called. */
-		goto complete_unlock;
-	}
-
-	if (status != DLM_NORMAL) {
-		mlog(ML_ERROR, "Dlm passes status %d for lock %s, "
-		     "unlock_action %d\n", status, lockres->l_name,
+	if (error) {
+		mlog(ML_ERROR, "Dlm passes error %d for lock %s, "
+		     "unlock_action %d\n", error, lockres->l_name,
 		     lockres->l_unlock_action);
 		spin_unlock_irqrestore(&lockres->l_lock, flags);
 		return;
@@ -2624,14 +2718,13 @@ static void ocfs2_unlock_ast(void *opaque, enum dlm_status status)
 		lockres->l_action = OCFS2_AST_INVALID;
 		break;
 	case OCFS2_UNLOCK_DROP_LOCK:
-		lockres->l_level = LKM_IVMODE;
+		lockres->l_level = DLM_LOCK_IV;
 		break;
 	default:
 		BUG();
 	}
 
 	lockres_clear_flags(lockres, OCFS2_LOCK_BUSY);
-complete_unlock:
 	lockres->l_unlock_action = OCFS2_UNLOCK_INVALID;
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
 
@@ -2643,16 +2736,16 @@ complete_unlock:
 static int ocfs2_drop_lock(struct ocfs2_super *osb,
 			   struct ocfs2_lock_res *lockres)
 {
-	enum dlm_status status;
+	int ret;
 	unsigned long flags;
-	int lkm_flags = 0;
+	u32 lkm_flags = 0;
 
 	/* We didn't get anywhere near actually using this lockres. */
 	if (!(lockres->l_flags & OCFS2_LOCK_INITIALIZED))
 		goto out;
 
 	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB)
-		lkm_flags |= LKM_VALBLK;
+		lkm_flags |= DLM_LKF_VALBLK;
 
 	spin_lock_irqsave(&lockres->l_lock, flags);
 
@@ -2678,7 +2771,7 @@ static int ocfs2_drop_lock(struct ocfs2_super *osb,
 
 	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
 		if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
-		    lockres->l_level == LKM_EXMODE &&
+		    lockres->l_level == DLM_LOCK_EX &&
 		    !(lockres->l_flags & OCFS2_LOCK_NEEDS_REFRESH))
 			lockres->l_ops->set_lvb(lockres);
 	}
@@ -2707,15 +2800,15 @@ static int ocfs2_drop_lock(struct ocfs2_super *osb,
 
 	mlog(0, "lock %s\n", lockres->l_name);
 
-	status = dlmunlock(osb->dlm, &lockres->l_lksb, lkm_flags,
-			   ocfs2_unlock_ast, lockres);
-	if (status != DLM_NORMAL) {
-		ocfs2_log_dlm_error("dlmunlock", status, lockres);
+	ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb, lkm_flags,
+			       lockres);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
 		mlog(ML_ERROR, "lockres flags: %lu\n", lockres->l_flags);
-		dlm_print_one_lock(lockres->l_lksb.lockid);
+		ocfs2_dlm_dump_lksb(&lockres->l_lksb);
 		BUG();
 	}
-	mlog(0, "lock %s, successfull return from dlmunlock\n",
+	mlog(0, "lock %s, successfull return from ocfs2_dlm_unlock\n",
 	     lockres->l_name);
 
 	ocfs2_wait_on_busy_lock(lockres);
@@ -2806,15 +2899,15 @@ int ocfs2_drop_inode_locks(struct inode *inode)
 	return status;
 }
 
-static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
-				      int new_level)
+static unsigned int ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
+					      int new_level)
 {
 	assert_spin_locked(&lockres->l_lock);
 
-	BUG_ON(lockres->l_blocking <= LKM_NLMODE);
+	BUG_ON(lockres->l_blocking <= DLM_LOCK_NL);
 
 	if (lockres->l_level <= new_level) {
-		mlog(ML_ERROR, "lockres->l_level (%u) <= new_level (%u)\n",
+		mlog(ML_ERROR, "lockres->l_level (%d) <= new_level (%d)\n",
 		     lockres->l_level, new_level);
 		BUG();
 	}
@@ -2825,33 +2918,33 @@ static void ocfs2_prepare_downconvert(struct ocfs2_lock_res *lockres,
 	lockres->l_action = OCFS2_AST_DOWNCONVERT;
 	lockres->l_requested = new_level;
 	lockres_or_flags(lockres, OCFS2_LOCK_BUSY);
+	return lockres_set_pending(lockres);
 }
 
 static int ocfs2_downconvert_lock(struct ocfs2_super *osb,
 				  struct ocfs2_lock_res *lockres,
 				  int new_level,
-				  int lvb)
+				  int lvb,
+				  unsigned int generation)
 {
-	int ret, dlm_flags = LKM_CONVERT;
-	enum dlm_status status;
+	int ret;
+	u32 dlm_flags = DLM_LKF_CONVERT;
 
 	mlog_entry_void();
 
 	if (lvb)
-		dlm_flags |= LKM_VALBLK;
-
-	status = dlmlock(osb->dlm,
-			 new_level,
-			 &lockres->l_lksb,
-			 dlm_flags,
-			 lockres->l_name,
-			 OCFS2_LOCK_ID_MAX_LEN - 1,
-			 ocfs2_locking_ast,
-			 lockres,
-			 ocfs2_blocking_ast);
-	if (status != DLM_NORMAL) {
-		ocfs2_log_dlm_error("dlmlock", status, lockres);
-		ret = -EINVAL;
+		dlm_flags |= DLM_LKF_VALBLK;
+
+	ret = ocfs2_dlm_lock(osb->cconn,
+			     new_level,
+			     &lockres->l_lksb,
+			     dlm_flags,
+			     lockres->l_name,
+			     OCFS2_LOCK_ID_MAX_LEN - 1,
+			     lockres);
+	lockres_clear_pending(lockres, generation, osb);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_lock", ret, lockres);
 		ocfs2_recover_from_dlm_error(lockres, 1);
 		goto bail;
 	}
@@ -2862,7 +2955,7 @@ bail:
 	return ret;
 }
 
-/* returns 1 when the caller should unlock and call dlmunlock */
+/* returns 1 when the caller should unlock and call ocfs2_dlm_unlock */
 static int ocfs2_prepare_cancel_convert(struct ocfs2_super *osb,
 				        struct ocfs2_lock_res *lockres)
 {
@@ -2898,24 +2991,18 @@ static int ocfs2_cancel_convert(struct ocfs2_super *osb,
 				struct ocfs2_lock_res *lockres)
 {
 	int ret;
-	enum dlm_status status;
 
 	mlog_entry_void();
 	mlog(0, "lock %s\n", lockres->l_name);
 
-	ret = 0;
-	status = dlmunlock(osb->dlm,
-			   &lockres->l_lksb,
-			   LKM_CANCEL,
-			   ocfs2_unlock_ast,
-			   lockres);
-	if (status != DLM_NORMAL) {
-		ocfs2_log_dlm_error("dlmunlock", status, lockres);
-		ret = -EINVAL;
+	ret = ocfs2_dlm_unlock(osb->cconn, &lockres->l_lksb,
+			       DLM_LKF_CANCEL, lockres);
+	if (ret) {
+		ocfs2_log_dlm_error("ocfs2_dlm_unlock", ret, lockres);
 		ocfs2_recover_from_dlm_error(lockres, 0);
 	}
 
-	mlog(0, "lock %s return from dlmunlock\n", lockres->l_name);
+	mlog(0, "lock %s return from ocfs2_dlm_unlock\n", lockres->l_name);
 
 	mlog_exit(ret);
 	return ret;
@@ -2930,6 +3017,7 @@ static int ocfs2_unblock_lock(struct ocfs2_super *osb,
 	int new_level;
 	int ret = 0;
 	int set_lvb = 0;
+	unsigned int gen;
 
 	mlog_entry_void();
 
@@ -2939,6 +3027,32 @@ static int ocfs2_unblock_lock(struct ocfs2_super *osb,
 
 recheck:
 	if (lockres->l_flags & OCFS2_LOCK_BUSY) {
+		/* XXX
+		 * This is a *big* race.  The OCFS2_LOCK_PENDING flag
+		 * exists entirely for one reason - another thread has set
+		 * OCFS2_LOCK_BUSY, but has *NOT* yet called dlm_lock().
+		 *
+		 * If we do ocfs2_cancel_convert() before the other thread
+		 * calls dlm_lock(), our cancel will do nothing.  We will
+		 * get no ast, and we will have no way of knowing the
+		 * cancel failed.  Meanwhile, the other thread will call
+		 * into dlm_lock() and wait...forever.
+		 *
+		 * Why forever?  Because another node has asked for the
+		 * lock first; that's why we're here in unblock_lock().
+		 *
+		 * The solution is OCFS2_LOCK_PENDING.  When PENDING is
+		 * set, we just requeue the unblock.  Only when the other
+		 * thread has called dlm_lock() and cleared PENDING will
+		 * we then cancel their request.
+		 *
+		 * All callers of dlm_lock() must set OCFS2_DLM_PENDING
+		 * at the same time they set OCFS2_DLM_BUSY.  They must
+		 * clear OCFS2_DLM_PENDING after dlm_lock() returns.
+		 */
+		if (lockres->l_flags & OCFS2_LOCK_PENDING)
+			goto leave_requeue;
+
 		ctl->requeue = 1;
 		ret = ocfs2_prepare_cancel_convert(osb, lockres);
 		spin_unlock_irqrestore(&lockres->l_lock, flags);
@@ -2952,13 +3066,13 @@ recheck:
 
 	/* if we're blocking an exclusive and we have *any* holders,
 	 * then requeue. */
-	if ((lockres->l_blocking == LKM_EXMODE)
+	if ((lockres->l_blocking == DLM_LOCK_EX)
 	    && (lockres->l_ex_holders || lockres->l_ro_holders))
 		goto leave_requeue;
 
 	/* If it's a PR we're blocking, then only
 	 * requeue if we've got any EX holders */
-	if (lockres->l_blocking == LKM_PRMODE &&
+	if (lockres->l_blocking == DLM_LOCK_PR &&
 	    lockres->l_ex_holders)
 		goto leave_requeue;
 
@@ -3005,7 +3119,7 @@ downconvert:
 	ctl->requeue = 0;
 
 	if (lockres->l_ops->flags & LOCK_TYPE_USES_LVB) {
-		if (lockres->l_level == LKM_EXMODE)
+		if (lockres->l_level == DLM_LOCK_EX)
 			set_lvb = 1;
 
 		/*
@@ -3018,9 +3132,11 @@ downconvert:
 			lockres->l_ops->set_lvb(lockres);
 	}
 
-	ocfs2_prepare_downconvert(lockres, new_level);
+	gen = ocfs2_prepare_downconvert(lockres, new_level);
 	spin_unlock_irqrestore(&lockres->l_lock, flags);
-	ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb);
+	ret = ocfs2_downconvert_lock(osb, lockres, new_level, set_lvb,
+				     gen);
+
 leave:
 	mlog_exit(ret);
 	return ret;
@@ -3059,7 +3175,7 @@ static int ocfs2_data_convert_worker(struct ocfs2_lock_res *lockres,
 		     (unsigned long long)OCFS2_I(inode)->ip_blkno);
 	}
 	sync_mapping_buffers(mapping);
-	if (blocking == LKM_EXMODE) {
+	if (blocking == DLM_LOCK_EX) {
 		truncate_inode_pages(mapping, 0);
 	} else {
 		/* We only need to wait on the I/O if we're not also
@@ -3080,8 +3196,8 @@ static int ocfs2_check_meta_downconvert(struct ocfs2_lock_res *lockres,
 	struct inode *inode = ocfs2_lock_res_inode(lockres);
 	int checkpointed = ocfs2_inode_fully_checkpointed(inode);
 
-	BUG_ON(new_level != LKM_NLMODE && new_level != LKM_PRMODE);
-	BUG_ON(lockres->l_level != LKM_EXMODE && !checkpointed);
+	BUG_ON(new_level != DLM_LOCK_NL && new_level != DLM_LOCK_PR);
+	BUG_ON(lockres->l_level != DLM_LOCK_EX && !checkpointed);
 
 	if (checkpointed)
 		return 1;
@@ -3145,7 +3261,7 @@ static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
 	 * valid. The downconvert code will retain a PR for this node,
 	 * so there's no further work to do.
 	 */
-	if (blocking == LKM_PRMODE)
+	if (blocking == DLM_LOCK_PR)
 		return UNBLOCK_CONTINUE;
 
 	/*
@@ -3219,6 +3335,45 @@ static int ocfs2_dentry_convert_worker(struct ocfs2_lock_res *lockres,
 	return UNBLOCK_CONTINUE_POST;
 }
 
+/*
+ * This is the filesystem locking protocol.  It provides the lock handling
+ * hooks for the underlying DLM.  It has a maximum version number.
+ * The version number allows interoperability with systems running at
+ * the same major number and an equal or smaller minor number.
+ *
+ * Whenever the filesystem does new things with locks (adds or removes a
+ * lock, orders them differently, does different things underneath a lock),
+ * the version must be changed.  The protocol is negotiated when joining
+ * the dlm domain.  A node may join the domain if its major version is
+ * identical to all other nodes and its minor version is greater than
+ * or equal to all other nodes.  When its minor version is greater than
+ * the other nodes, it will run at the minor version specified by the
+ * other nodes.
+ *
+ * If a locking change is made that will not be compatible with older
+ * versions, the major number must be increased and the minor version set
+ * to zero.  If a change merely adds a behavior that can be disabled when
+ * speaking to older versions, the minor version must be increased.  If a
+ * change adds a fully backwards compatible change (eg, LVB changes that
+ * are just ignored by older versions), the version does not need to be
+ * updated.
+ */
+static struct ocfs2_locking_protocol lproto = {
+	.lp_max_version = {
+		.pv_major = OCFS2_LOCKING_PROTOCOL_MAJOR,
+		.pv_minor = OCFS2_LOCKING_PROTOCOL_MINOR,
+	},
+	.lp_lock_ast		= ocfs2_locking_ast,
+	.lp_blocking_ast	= ocfs2_blocking_ast,
+	.lp_unlock_ast		= ocfs2_unlock_ast,
+};
+
+void ocfs2_set_locking_protocol(void)
+{
+	ocfs2_stack_glue_set_locking_protocol(&lproto);
+}
+
+
 static void ocfs2_process_blocked_lock(struct ocfs2_super *osb,
 				       struct ocfs2_lock_res *lockres)
 {
diff --git a/fs/ocfs2/dlmglue.h b/fs/ocfs2/dlmglue.h
index e3cf902404b..2bb01f09c1b 100644
--- a/fs/ocfs2/dlmglue.h
+++ b/fs/ocfs2/dlmglue.h
@@ -58,7 +58,7 @@ struct ocfs2_meta_lvb {
 #define OCFS2_LOCK_NONBLOCK		(0x04)
 
 int ocfs2_dlm_init(struct ocfs2_super *osb);
-void ocfs2_dlm_shutdown(struct ocfs2_super *osb);
+void ocfs2_dlm_shutdown(struct ocfs2_super *osb, int hangup_pending);
 void ocfs2_lock_res_init_once(struct ocfs2_lock_res *res);
 void ocfs2_inode_lock_res_init(struct ocfs2_lock_res *res,
 			       enum ocfs2_lock_type type,
@@ -114,5 +114,6 @@ void ocfs2_wake_downconvert_thread(struct ocfs2_super *osb);
 struct ocfs2_dlm_debug *ocfs2_new_dlm_debug(void);
 void ocfs2_put_dlm_debug(struct ocfs2_dlm_debug *dlm_debug);
 
-extern const struct dlm_protocol_version ocfs2_locking_protocol;
+/* To set the locking protocol on module initialization */
+void ocfs2_set_locking_protocol(void);
 #endif	/* DLMGLUE_H */
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index ed5d5232e85..9154c82d325 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2242,7 +2242,7 @@ const struct file_operations ocfs2_fops = {
 	.open		= ocfs2_file_open,
 	.aio_read	= ocfs2_file_aio_read,
 	.aio_write	= ocfs2_file_aio_write,
-	.ioctl		= ocfs2_ioctl,
+	.unlocked_ioctl	= ocfs2_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl   = ocfs2_compat_ioctl,
 #endif
@@ -2258,7 +2258,7 @@ const struct file_operations ocfs2_dops = {
 	.fsync		= ocfs2_sync_file,
 	.release	= ocfs2_dir_release,
 	.open		= ocfs2_dir_open,
-	.ioctl		= ocfs2_ioctl,
+	.unlocked_ioctl	= ocfs2_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl   = ocfs2_compat_ioctl,
 #endif
diff --git a/fs/ocfs2/heartbeat.c b/fs/ocfs2/heartbeat.c
index 0758daf64da..c6e7213db86 100644
--- a/fs/ocfs2/heartbeat.c
+++ b/fs/ocfs2/heartbeat.c
@@ -28,9 +28,6 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
-#include <linux/kmod.h>
-
-#include <dlm/dlmapi.h>
 
 #define MLOG_MASK_PREFIX ML_SUPER
 #include <cluster/masklog.h>
@@ -48,7 +45,6 @@ static inline void __ocfs2_node_map_set_bit(struct ocfs2_node_map *map,
 					    int bit);
 static inline void __ocfs2_node_map_clear_bit(struct ocfs2_node_map *map,
 					      int bit);
-static inline int __ocfs2_node_map_is_empty(struct ocfs2_node_map *map);
 
 /* special case -1 for now
  * TODO: should *really* make sure the calling func never passes -1!!  */
@@ -62,23 +58,23 @@ static void ocfs2_node_map_init(struct ocfs2_node_map *map)
 void ocfs2_init_node_maps(struct ocfs2_super *osb)
 {
 	spin_lock_init(&osb->node_map_lock);
-	ocfs2_node_map_init(&osb->recovery_map);
 	ocfs2_node_map_init(&osb->osb_recovering_orphan_dirs);
 }
 
-static void ocfs2_do_node_down(int node_num,
-			       struct ocfs2_super *osb)
+void ocfs2_do_node_down(int node_num, void *data)
 {
+	struct ocfs2_super *osb = data;
+
 	BUG_ON(osb->node_num == node_num);
 
 	mlog(0, "ocfs2: node down event for %d\n", node_num);
 
-	if (!osb->dlm) {
+	if (!osb->cconn) {
 		/*
-		 * No DLM means we're not even ready to participate yet.
-		 * We check the slots after the DLM comes up, so we will
-		 * notice the node death then.  We can safely ignore it
-		 * here.
+		 * No cluster connection means we're not even ready to
+		 * participate yet.  We check the slots after the cluster
+		 * comes up, so we will notice the node death then.  We
+		 * can safely ignore it here.
 		 */
 		return;
 	}
@@ -86,61 +82,6 @@ static void ocfs2_do_node_down(int node_num,
 	ocfs2_recovery_thread(osb, node_num);
 }
 
-/* Called from the dlm when it's about to evict a node. We may also
- * get a heartbeat callback later. */
-static void ocfs2_dlm_eviction_cb(int node_num,
-				  void *data)
-{
-	struct ocfs2_super *osb = (struct ocfs2_super *) data;
-	struct super_block *sb = osb->sb;
-
-	mlog(ML_NOTICE, "device (%u,%u): dlm has evicted node %d\n",
-	     MAJOR(sb->s_dev), MINOR(sb->s_dev), node_num);
-
-	ocfs2_do_node_down(node_num, osb);
-}
-
-void ocfs2_setup_hb_callbacks(struct ocfs2_super *osb)
-{
-	/* Not exactly a heartbeat callback, but leads to essentially
-	 * the same path so we set it up here. */
-	dlm_setup_eviction_cb(&osb->osb_eviction_cb,
-			      ocfs2_dlm_eviction_cb,
-			      osb);
-}
-
-void ocfs2_stop_heartbeat(struct ocfs2_super *osb)
-{
-	int ret;
-	char *argv[5], *envp[3];
-
-	if (ocfs2_mount_local(osb))
-		return;
-
-	if (!osb->uuid_str) {
-		/* This can happen if we don't get far enough in mount... */
-		mlog(0, "No UUID with which to stop heartbeat!\n\n");
-		return;
-	}
-
-	argv[0] = (char *)o2nm_get_hb_ctl_path();
-	argv[1] = "-K";
-	argv[2] = "-u";
-	argv[3] = osb->uuid_str;
-	argv[4] = NULL;
-
-	mlog(0, "Run: %s %s %s %s\n", argv[0], argv[1], argv[2], argv[3]);
-
-	/* minimal command environment taken from cpu_run_sbin_hotplug */
-	envp[0] = "HOME=/";
-	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
-	envp[2] = NULL;
-
-	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
-	if (ret < 0)
-		mlog_errno(ret);
-}
-
 static inline void __ocfs2_node_map_set_bit(struct ocfs2_node_map *map,
 					    int bit)
 {
@@ -192,112 +133,3 @@ int ocfs2_node_map_test_bit(struct ocfs2_super *osb,
 	return ret;
 }
 
-static inline int __ocfs2_node_map_is_empty(struct ocfs2_node_map *map)
-{
-	int bit;
-	bit = find_next_bit(map->map, map->num_nodes, 0);
-	if (bit < map->num_nodes)
-		return 0;
-	return 1;
-}
-
-int ocfs2_node_map_is_empty(struct ocfs2_super *osb,
-			    struct ocfs2_node_map *map)
-{
-	int ret;
-	BUG_ON(map->num_nodes == 0);
-	spin_lock(&osb->node_map_lock);
-	ret = __ocfs2_node_map_is_empty(map);
-	spin_unlock(&osb->node_map_lock);
-	return ret;
-}
-
-#if 0
-
-static void __ocfs2_node_map_dup(struct ocfs2_node_map *target,
-				 struct ocfs2_node_map *from)
-{
-	BUG_ON(from->num_nodes == 0);
-	ocfs2_node_map_init(target);
-	__ocfs2_node_map_set(target, from);
-}
-
-/* returns 1 if bit is the only bit set in target, 0 otherwise */
-int ocfs2_node_map_is_only(struct ocfs2_super *osb,
-			   struct ocfs2_node_map *target,
-			   int bit)
-{
-	struct ocfs2_node_map temp;
-	int ret;
-
-	spin_lock(&osb->node_map_lock);
-	__ocfs2_node_map_dup(&temp, target);
-	__ocfs2_node_map_clear_bit(&temp, bit);
-	ret = __ocfs2_node_map_is_empty(&temp);
-	spin_unlock(&osb->node_map_lock);
-
-	return ret;
-}
-
-static void __ocfs2_node_map_set(struct ocfs2_node_map *target,
-				 struct ocfs2_node_map *from)
-{
-	int num_longs, i;
-
-	BUG_ON(target->num_nodes != from->num_nodes);
-	BUG_ON(target->num_nodes == 0);
-
-	num_longs = BITS_TO_LONGS(target->num_nodes);
-	for (i = 0; i < num_longs; i++)
-		target->map[i] = from->map[i];
-}
-
-#endif  /*  0  */
-
-/* Returns whether the recovery bit was actually set - it may not be
- * if a node is still marked as needing recovery */
-int ocfs2_recovery_map_set(struct ocfs2_super *osb,
-			   int num)
-{
-	int set = 0;
-
-	spin_lock(&osb->node_map_lock);
-
-	if (!test_bit(num, osb->recovery_map.map)) {
-	    __ocfs2_node_map_set_bit(&osb->recovery_map, num);
-	    set = 1;
-	}
-
-	spin_unlock(&osb->node_map_lock);
-
-	return set;
-}
-
-void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
-			      int num)
-{
-	ocfs2_node_map_clear_bit(osb, &osb->recovery_map, num);
-}
-
-int ocfs2_node_map_iterate(struct ocfs2_super *osb,
-			   struct ocfs2_node_map *map,
-			   int idx)
-{
-	int i = idx;
-
-	idx = O2NM_INVALID_NODE_NUM;
-	spin_lock(&osb->node_map_lock);
-	if ((i != O2NM_INVALID_NODE_NUM) &&
-	    (i >= 0) &&
-	    (i < map->num_nodes)) {
-		while(i < map->num_nodes) {
-			if (test_bit(i, map->map)) {
-				idx = i;
-				break;
-			}
-			i++;
-		}
-	}
-	spin_unlock(&osb->node_map_lock);
-	return idx;
-}
diff --git a/fs/ocfs2/heartbeat.h b/fs/ocfs2/heartbeat.h
index eac63aed761..74b9c5dda28 100644
--- a/fs/ocfs2/heartbeat.h
+++ b/fs/ocfs2/heartbeat.h
@@ -28,13 +28,10 @@
 
 void ocfs2_init_node_maps(struct ocfs2_super *osb);
 
-void ocfs2_setup_hb_callbacks(struct ocfs2_super *osb);
-void ocfs2_stop_heartbeat(struct ocfs2_super *osb);
+void ocfs2_do_node_down(int node_num, void *data);
 
 /* node map functions - used to keep track of mounted and in-recovery
  * nodes. */
-int ocfs2_node_map_is_empty(struct ocfs2_super *osb,
-			    struct ocfs2_node_map *map);
 void ocfs2_node_map_set_bit(struct ocfs2_super *osb,
 			    struct ocfs2_node_map *map,
 			    int bit);
@@ -44,17 +41,5 @@ void ocfs2_node_map_clear_bit(struct ocfs2_super *osb,
 int ocfs2_node_map_test_bit(struct ocfs2_super *osb,
 			    struct ocfs2_node_map *map,
 			    int bit);
-int ocfs2_node_map_iterate(struct ocfs2_super *osb,
-			   struct ocfs2_node_map *map,
-			   int idx);
-static inline int ocfs2_node_map_first_set_bit(struct ocfs2_super *osb,
-					       struct ocfs2_node_map *map)
-{
-	return ocfs2_node_map_iterate(osb, map, 0);
-}
-int ocfs2_recovery_map_set(struct ocfs2_super *osb,
-			   int num);
-void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
-			      int num);
 
 #endif /* OCFS2_HEARTBEAT_H */
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 5177fba5162..b413166dd16 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -7,6 +7,7 @@
 
 #include <linux/fs.h>
 #include <linux/mount.h>
+#include <linux/smp_lock.h>
 
 #define MLOG_MASK_PREFIX ML_INODE
 #include <cluster/masklog.h>
@@ -112,9 +113,9 @@ bail:
 	return status;
 }
 
-int ocfs2_ioctl(struct inode * inode, struct file * filp,
-	unsigned int cmd, unsigned long arg)
+long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
+	struct inode *inode = filp->f_path.dentry->d_inode;
 	unsigned int flags;
 	int new_clusters;
 	int status;
@@ -168,9 +169,6 @@ int ocfs2_ioctl(struct inode * inode, struct file * filp,
 #ifdef CONFIG_COMPAT
 long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
-	int ret;
-
 	switch (cmd) {
 	case OCFS2_IOC32_GETFLAGS:
 		cmd = OCFS2_IOC_GETFLAGS;
@@ -190,9 +188,6 @@ long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 		return -ENOIOCTLCMD;
 	}
 
-	lock_kernel();
-	ret = ocfs2_ioctl(inode, file, cmd, arg);
-	unlock_kernel();
-	return ret;
+	return ocfs2_ioctl(file, cmd, arg);
 }
 #endif
diff --git a/fs/ocfs2/ioctl.h b/fs/ocfs2/ioctl.h
index 4d6c4f430d0..cf9a5ee30fe 100644
--- a/fs/ocfs2/ioctl.h
+++ b/fs/ocfs2/ioctl.h
@@ -10,8 +10,7 @@
 #ifndef OCFS2_IOCTL_H
 #define OCFS2_IOCTL_H
 
-int ocfs2_ioctl(struct inode * inode, struct file * filp,
-	unsigned int cmd, unsigned long arg);
+long ocfs2_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg);
 
 #endif /* OCFS2_IOCTL_H */
diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index f31c7e8c19c..9698338adc3 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -64,6 +64,137 @@ static int ocfs2_recover_orphans(struct ocfs2_super *osb,
 				 int slot);
 static int ocfs2_commit_thread(void *arg);
 
+
+/*
+ * The recovery_list is a simple linked list of node numbers to recover.
+ * It is protected by the recovery_lock.
+ */
+
+struct ocfs2_recovery_map {
+	unsigned int rm_used;
+	unsigned int *rm_entries;
+};
+
+int ocfs2_recovery_init(struct ocfs2_super *osb)
+{
+	struct ocfs2_recovery_map *rm;
+
+	mutex_init(&osb->recovery_lock);
+	osb->disable_recovery = 0;
+	osb->recovery_thread_task = NULL;
+	init_waitqueue_head(&osb->recovery_event);
+
+	rm = kzalloc(sizeof(struct ocfs2_recovery_map) +
+		     osb->max_slots * sizeof(unsigned int),
+		     GFP_KERNEL);
+	if (!rm) {
+		mlog_errno(-ENOMEM);
+		return -ENOMEM;
+	}
+
+	rm->rm_entries = (unsigned int *)((char *)rm +
+					  sizeof(struct ocfs2_recovery_map));
+	osb->recovery_map = rm;
+
+	return 0;
+}
+
+/* we can't grab the goofy sem lock from inside wait_event, so we use
+ * memory barriers to make sure that we'll see the null task before
+ * being woken up */
+static int ocfs2_recovery_thread_running(struct ocfs2_super *osb)
+{
+	mb();
+	return osb->recovery_thread_task != NULL;
+}
+
+void ocfs2_recovery_exit(struct ocfs2_super *osb)
+{
+	struct ocfs2_recovery_map *rm;
+
+	/* disable any new recovery threads and wait for any currently
+	 * running ones to exit. Do this before setting the vol_state. */
+	mutex_lock(&osb->recovery_lock);
+	osb->disable_recovery = 1;
+	mutex_unlock(&osb->recovery_lock);
+	wait_event(osb->recovery_event, !ocfs2_recovery_thread_running(osb));
+
+	/* At this point, we know that no more recovery threads can be
+	 * launched, so wait for any recovery completion work to
+	 * complete. */
+	flush_workqueue(ocfs2_wq);
+
+	/*
+	 * Now that recovery is shut down, and the osb is about to be
+	 * freed,  the osb_lock is not taken here.
+	 */
+	rm = osb->recovery_map;
+	/* XXX: Should we bug if there are dirty entries? */
+
+	kfree(rm);
+}
+
+static int __ocfs2_recovery_map_test(struct ocfs2_super *osb,
+				     unsigned int node_num)
+{
+	int i;
+	struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+	assert_spin_locked(&osb->osb_lock);
+
+	for (i = 0; i < rm->rm_used; i++) {
+		if (rm->rm_entries[i] == node_num)
+			return 1;
+	}
+
+	return 0;
+}
+
+/* Behaves like test-and-set.  Returns the previous value */
+static int ocfs2_recovery_map_set(struct ocfs2_super *osb,
+				  unsigned int node_num)
+{
+	struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+	spin_lock(&osb->osb_lock);
+	if (__ocfs2_recovery_map_test(osb, node_num)) {
+		spin_unlock(&osb->osb_lock);
+		return 1;
+	}
+
+	/* XXX: Can this be exploited? Not from o2dlm... */
+	BUG_ON(rm->rm_used >= osb->max_slots);
+
+	rm->rm_entries[rm->rm_used] = node_num;
+	rm->rm_used++;
+	spin_unlock(&osb->osb_lock);
+
+	return 0;
+}
+
+static void ocfs2_recovery_map_clear(struct ocfs2_super *osb,
+				     unsigned int node_num)
+{
+	int i;
+	struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+	spin_lock(&osb->osb_lock);
+
+	for (i = 0; i < rm->rm_used; i++) {
+		if (rm->rm_entries[i] == node_num)
+			break;
+	}
+
+	if (i < rm->rm_used) {
+		/* XXX: be careful with the pointer math */
+		memmove(&(rm->rm_entries[i]), &(rm->rm_entries[i + 1]),
+			(rm->rm_used - i - 1) * sizeof(unsigned int));
+		rm->rm_used--;
+	}
+
+	spin_unlock(&osb->osb_lock);
+}
+
 static int ocfs2_commit_cache(struct ocfs2_super *osb)
 {
 	int status = 0;
@@ -586,8 +717,7 @@ int ocfs2_journal_load(struct ocfs2_journal *journal, int local)
 
 	mlog_entry_void();
 
-	if (!journal)
-		BUG();
+	BUG_ON(!journal);
 
 	osb = journal->j_osb;
 
@@ -650,6 +780,23 @@ bail:
 	return status;
 }
 
+static int ocfs2_recovery_completed(struct ocfs2_super *osb)
+{
+	int empty;
+	struct ocfs2_recovery_map *rm = osb->recovery_map;
+
+	spin_lock(&osb->osb_lock);
+	empty = (rm->rm_used == 0);
+	spin_unlock(&osb->osb_lock);
+
+	return empty;
+}
+
+void ocfs2_wait_for_recovery(struct ocfs2_super *osb)
+{
+	wait_event(osb->recovery_event, ocfs2_recovery_completed(osb));
+}
+
 /*
  * JBD Might read a cached version of another nodes journal file. We
  * don't want this as this file changes often and we get no
@@ -848,6 +995,7 @@ static int __ocfs2_recovery_thread(void *arg)
 {
 	int status, node_num;
 	struct ocfs2_super *osb = arg;
+	struct ocfs2_recovery_map *rm = osb->recovery_map;
 
 	mlog_entry_void();
 
@@ -863,26 +1011,29 @@ restart:
 		goto bail;
 	}
 
-	while(!ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
-		node_num = ocfs2_node_map_first_set_bit(osb,
-							&osb->recovery_map);
-		if (node_num == O2NM_INVALID_NODE_NUM) {
-			mlog(0, "Out of nodes to recover.\n");
-			break;
-		}
+	spin_lock(&osb->osb_lock);
+	while (rm->rm_used) {
+		/* It's always safe to remove entry zero, as we won't
+		 * clear it until ocfs2_recover_node() has succeeded. */
+		node_num = rm->rm_entries[0];
+		spin_unlock(&osb->osb_lock);
 
 		status = ocfs2_recover_node(osb, node_num);
-		if (status < 0) {
+		if (!status) {
+			ocfs2_recovery_map_clear(osb, node_num);
+		} else {
 			mlog(ML_ERROR,
 			     "Error %d recovering node %d on device (%u,%u)!\n",
 			     status, node_num,
 			     MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));
 			mlog(ML_ERROR, "Volume requires unmount.\n");
-			continue;
 		}
 
-		ocfs2_recovery_map_clear(osb, node_num);
+		spin_lock(&osb->osb_lock);
 	}
+	spin_unlock(&osb->osb_lock);
+	mlog(0, "All nodes recovered\n");
+
 	ocfs2_super_unlock(osb, 1);
 
 	/* We always run recovery on our own orphan dir - the dead
@@ -893,8 +1044,7 @@ restart:
 
 bail:
 	mutex_lock(&osb->recovery_lock);
-	if (!status &&
-	    !ocfs2_node_map_is_empty(osb, &osb->recovery_map)) {
+	if (!status && !ocfs2_recovery_completed(osb)) {
 		mutex_unlock(&osb->recovery_lock);
 		goto restart;
 	}
@@ -924,8 +1074,8 @@ void ocfs2_recovery_thread(struct ocfs2_super *osb, int node_num)
 
 	/* People waiting on recovery will wait on
 	 * the recovery map to empty. */
-	if (!ocfs2_recovery_map_set(osb, node_num))
-		mlog(0, "node %d already be in recovery.\n", node_num);
+	if (ocfs2_recovery_map_set(osb, node_num))
+		mlog(0, "node %d already in recovery map.\n", node_num);
 
 	mlog(0, "starting recovery thread...\n");
 
@@ -1079,7 +1229,6 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
 {
 	int status = 0;
 	int slot_num;
-	struct ocfs2_slot_info *si = osb->slot_info;
 	struct ocfs2_dinode *la_copy = NULL;
 	struct ocfs2_dinode *tl_copy = NULL;
 
@@ -1092,8 +1241,8 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
 	 * case we should've called ocfs2_journal_load instead. */
 	BUG_ON(osb->node_num == node_num);
 
-	slot_num = ocfs2_node_num_to_slot(si, node_num);
-	if (slot_num == OCFS2_INVALID_SLOT) {
+	slot_num = ocfs2_node_num_to_slot(osb, node_num);
+	if (slot_num == -ENOENT) {
 		status = 0;
 		mlog(0, "no slot for this node, so no recovery required.\n");
 		goto done;
@@ -1123,8 +1272,7 @@ static int ocfs2_recover_node(struct ocfs2_super *osb,
 
 	/* Likewise, this would be a strange but ultimately not so
 	 * harmful place to get an error... */
-	ocfs2_clear_slot(si, slot_num);
-	status = ocfs2_update_disk_slots(osb, si);
+	status = ocfs2_clear_slot(osb, slot_num);
 	if (status < 0)
 		mlog_errno(status);
 
@@ -1184,23 +1332,24 @@ bail:
  * slot info struct has been updated from disk. */
 int ocfs2_mark_dead_nodes(struct ocfs2_super *osb)
 {
-	int status, i, node_num;
-	struct ocfs2_slot_info *si = osb->slot_info;
+	unsigned int node_num;
+	int status, i;
 
 	/* This is called with the super block cluster lock, so we
 	 * know that the slot map can't change underneath us. */
 
-	spin_lock(&si->si_lock);
-	for(i = 0; i < si->si_num_slots; i++) {
+	spin_lock(&osb->osb_lock);
+	for (i = 0; i < osb->max_slots; i++) {
 		if (i == osb->slot_num)
 			continue;
-		if (ocfs2_is_empty_slot(si, i))
+
+		status = ocfs2_slot_to_node_num_locked(osb, i, &node_num);
+		if (status == -ENOENT)
 			continue;
 
-		node_num = si->si_global_node_nums[i];
-		if (ocfs2_node_map_test_bit(osb, &osb->recovery_map, node_num))
+		if (__ocfs2_recovery_map_test(osb, node_num))
 			continue;
-		spin_unlock(&si->si_lock);
+		spin_unlock(&osb->osb_lock);
 
 		/* Ok, we have a slot occupied by another node which
 		 * is not in the recovery map. We trylock his journal
@@ -1216,9 +1365,9 @@ int ocfs2_mark_dead_nodes(struct ocfs2_super *osb)
 			goto bail;
 		}
 
-		spin_lock(&si->si_lock);
+		spin_lock(&osb->osb_lock);
 	}
-	spin_unlock(&si->si_lock);
+	spin_unlock(&osb->osb_lock);
 
 	status = 0;
 bail:
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 220f3e818e7..db82be2532e 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -134,6 +134,10 @@ static inline void ocfs2_inode_set_new(struct ocfs2_super *osb,
 
 /* Exported only for the journal struct init code in super.c. Do not call. */
 void ocfs2_complete_recovery(struct work_struct *work);
+void ocfs2_wait_for_recovery(struct ocfs2_super *osb);
+
+int ocfs2_recovery_init(struct ocfs2_super *osb);
+void ocfs2_recovery_exit(struct ocfs2_super *osb);
 
 /*
  *  Journal Control:
diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
index ab83fd56242..ce0dc147602 100644
--- a/fs/ocfs2/localalloc.c
+++ b/fs/ocfs2/localalloc.c
@@ -447,6 +447,8 @@ out_mutex:
 	iput(main_bm_inode);
 
 out:
+	if (!status)
+		ocfs2_init_inode_steal_slot(osb);
 	mlog_exit(status);
 	return status;
 }
@@ -523,6 +525,8 @@ int ocfs2_reserve_local_alloc_bits(struct ocfs2_super *osb,
 	}
 
 	ac->ac_inode = local_alloc_inode;
+	/* We should never use localalloc from another slot */
+	ac->ac_alloc_slot = osb->slot_num;
 	ac->ac_which = OCFS2_AC_USE_LOCAL;
 	get_bh(osb->local_alloc_bh);
 	ac->ac_bh = osb->local_alloc_bh;
diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index ae9ad958751..d5d808fe014 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -424,7 +424,7 @@ static int ocfs2_mknod_locked(struct ocfs2_super *osb,
 	fe->i_fs_generation = cpu_to_le32(osb->fs_generation);
 	fe->i_blkno = cpu_to_le64(fe_blkno);
 	fe->i_suballoc_bit = cpu_to_le16(suballoc_bit);
-	fe->i_suballoc_slot = cpu_to_le16(osb->slot_num);
+	fe->i_suballoc_slot = cpu_to_le16(inode_ac->ac_alloc_slot);
 	fe->i_uid = cpu_to_le32(current->fsuid);
 	if (dir->i_mode & S_ISGID) {
 		fe->i_gid = cpu_to_le32(dir->i_gid);
@@ -997,7 +997,7 @@ static int ocfs2_rename(struct inode *old_dir,
 	 *
 	 * And that's why, just like the VFS, we need a file system
 	 * rename lock. */
-	if (old_dentry != new_dentry) {
+	if (old_dir != new_dir && S_ISDIR(old_inode->i_mode)) {
 		status = ocfs2_rename_lock(osb);
 		if (status < 0) {
 			mlog_errno(status);
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 6546cef212e..31692379c17 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -36,11 +36,8 @@
 #include <linux/mutex.h>
 #include <linux/jbd.h>
 
-#include "cluster/nodemanager.h"
-#include "cluster/heartbeat.h"
-#include "cluster/tcp.h"
-
-#include "dlm/dlmapi.h"
+/* For union ocfs2_dlm_lksb */
+#include "stackglue.h"
 
 #include "ocfs2_fs.h"
 #include "ocfs2_lockid.h"
@@ -101,6 +98,9 @@ enum ocfs2_unlock_action {
 					       * dropped. */
 #define OCFS2_LOCK_QUEUED        (0x00000100) /* queued for downconvert */
 #define OCFS2_LOCK_NOCACHE       (0x00000200) /* don't use a holder count */
+#define OCFS2_LOCK_PENDING       (0x00000400) /* This lockres is pending a
+						 call to dlm_lock.  Only
+						 exists with BUSY set. */
 
 struct ocfs2_lock_res_ops;
 
@@ -120,13 +120,14 @@ struct ocfs2_lock_res {
 	int                      l_level;
 	unsigned int             l_ro_holders;
 	unsigned int             l_ex_holders;
-	struct dlm_lockstatus    l_lksb;
+	union ocfs2_dlm_lksb     l_lksb;
 
 	/* used from AST/BAST funcs. */
 	enum ocfs2_ast_action    l_action;
 	enum ocfs2_unlock_action l_unlock_action;
 	int                      l_requested;
 	int                      l_blocking;
+	unsigned int             l_pending_gen;
 
 	wait_queue_head_t        l_event;
 
@@ -179,6 +180,8 @@ enum ocfs2_mount_options
 #define OCFS2_DEFAULT_ATIME_QUANTUM	60
 
 struct ocfs2_journal;
+struct ocfs2_slot_info;
+struct ocfs2_recovery_map;
 struct ocfs2_super
 {
 	struct task_struct *commit_task;
@@ -190,7 +193,6 @@ struct ocfs2_super
 	struct ocfs2_slot_info *slot_info;
 
 	spinlock_t node_map_lock;
-	struct ocfs2_node_map recovery_map;
 
 	u64 root_blkno;
 	u64 system_dir_blkno;
@@ -206,25 +208,29 @@ struct ocfs2_super
 	u32 s_feature_incompat;
 	u32 s_feature_ro_compat;
 
-	/* Protects s_next_generaion, osb_flags. Could protect more on
-	 * osb as it's very short lived. */
+	/* Protects s_next_generation, osb_flags and s_inode_steal_slot.
+	 * Could protect more on osb as it's very short lived.
+	 */
 	spinlock_t osb_lock;
 	u32 s_next_generation;
 	unsigned long osb_flags;
+	s16 s_inode_steal_slot;
+	atomic_t s_num_inodes_stolen;
 
 	unsigned long s_mount_opt;
 	unsigned int s_atime_quantum;
 
-	u16 max_slots;
-	s16 node_num;
-	s16 slot_num;
-	s16 preferred_slot;
+	unsigned int max_slots;
+	unsigned int node_num;
+	int slot_num;
+	int preferred_slot;
 	int s_sectsize_bits;
 	int s_clustersize;
 	int s_clustersize_bits;
 
 	atomic_t vol_state;
 	struct mutex recovery_lock;
+	struct ocfs2_recovery_map *recovery_map;
 	struct task_struct *recovery_thread_task;
 	int disable_recovery;
 	wait_queue_head_t checkpoint_event;
@@ -245,12 +251,11 @@ struct ocfs2_super
 	struct ocfs2_alloc_stats alloc_stats;
 	char dev_str[20];		/* "major,minor" of the device */
 
-	struct dlm_ctxt *dlm;
+	char osb_cluster_stack[OCFS2_STACK_LABEL_LEN + 1];
+	struct ocfs2_cluster_connection *cconn;
 	struct ocfs2_lock_res osb_super_lockres;
 	struct ocfs2_lock_res osb_rename_lockres;
-	struct dlm_eviction_cb osb_eviction_cb;
 	struct ocfs2_dlm_debug *osb_dlm_debug;
-	struct dlm_protocol_version osb_locking_proto;
 
 	struct dentry *osb_debug_root;
 
@@ -367,11 +372,24 @@ static inline int ocfs2_is_soft_readonly(struct ocfs2_super *osb)
 	return ret;
 }
 
+static inline int ocfs2_userspace_stack(struct ocfs2_super *osb)
+{
+	return (osb->s_feature_incompat &
+		OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK);
+}
+
 static inline int ocfs2_mount_local(struct ocfs2_super *osb)
 {
 	return (osb->s_feature_incompat & OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT);
 }
 
+static inline int ocfs2_uses_extended_slot_map(struct ocfs2_super *osb)
+{
+	return (osb->s_feature_incompat &
+		OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP);
+}
+
+
 #define OCFS2_IS_VALID_DINODE(ptr)					\
 	(!strcmp((ptr)->i_signature, OCFS2_INODE_SIGNATURE))
 
@@ -522,6 +540,33 @@ static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
 	return pages_per_cluster;
 }
 
+static inline void ocfs2_init_inode_steal_slot(struct ocfs2_super *osb)
+{
+	spin_lock(&osb->osb_lock);
+	osb->s_inode_steal_slot = OCFS2_INVALID_SLOT;
+	spin_unlock(&osb->osb_lock);
+	atomic_set(&osb->s_num_inodes_stolen, 0);
+}
+
+static inline void ocfs2_set_inode_steal_slot(struct ocfs2_super *osb,
+					      s16 slot)
+{
+	spin_lock(&osb->osb_lock);
+	osb->s_inode_steal_slot = slot;
+	spin_unlock(&osb->osb_lock);
+}
+
+static inline s16 ocfs2_get_inode_steal_slot(struct ocfs2_super *osb)
+{
+	s16 slot;
+
+	spin_lock(&osb->osb_lock);
+	slot = osb->s_inode_steal_slot;
+	spin_unlock(&osb->osb_lock);
+
+	return slot;
+}
+
 #define ocfs2_set_bit ext2_set_bit
 #define ocfs2_clear_bit ext2_clear_bit
 #define ocfs2_test_bit ext2_test_bit
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 3633edd3982..52c42666515 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -88,7 +88,9 @@
 #define OCFS2_FEATURE_COMPAT_SUPP	OCFS2_FEATURE_COMPAT_BACKUP_SB
 #define OCFS2_FEATURE_INCOMPAT_SUPP	(OCFS2_FEATURE_INCOMPAT_LOCAL_MOUNT \
 					 | OCFS2_FEATURE_INCOMPAT_SPARSE_ALLOC \
-					 | OCFS2_FEATURE_INCOMPAT_INLINE_DATA)
+					 | OCFS2_FEATURE_INCOMPAT_INLINE_DATA \
+					 | OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP \
+					 | OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK)
 #define OCFS2_FEATURE_RO_COMPAT_SUPP	OCFS2_FEATURE_RO_COMPAT_UNWRITTEN
 
 /*
@@ -125,6 +127,21 @@
 /* Support for data packed into inode blocks */
 #define OCFS2_FEATURE_INCOMPAT_INLINE_DATA	0x0040
 
+/* Support for the extended slot map */
+#define OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP 0x100
+
+
+/*
+ * Support for alternate, userspace cluster stacks.  If set, the superblock
+ * field s_cluster_info contains a tag for the alternate stack in use as
+ * well as the name of the cluster being joined.
+ * mount.ocfs2 must pass in a matching stack name.
+ *
+ * If not set, the classic stack will be used.  This is compatbile with
+ * all older versions.
+ */
+#define OCFS2_FEATURE_INCOMPAT_USERSPACE_STACK	0x0080
+
 /*
  * backup superblock flag is used to indicate that this volume
  * has backup superblocks.
@@ -267,6 +284,10 @@ struct ocfs2_new_group_input {
 #define OCFS2_VOL_UUID_LEN		16
 #define OCFS2_MAX_VOL_LABEL_LEN		64
 
+/* The alternate, userspace stack fields */
+#define OCFS2_STACK_LABEL_LEN		4
+#define OCFS2_CLUSTER_NAME_LEN		16
+
 /* Journal limits (in bytes) */
 #define OCFS2_MIN_JOURNAL_SIZE		(4 * 1024 * 1024)
 
@@ -475,6 +496,47 @@ struct ocfs2_extent_block
 };
 
 /*
+ * On disk slot map for OCFS2.  This defines the contents of the "slot_map"
+ * system file.  A slot is valid if it contains a node number >= 0.  The
+ * value -1 (0xFFFF) is OCFS2_INVALID_SLOT.  This marks a slot empty.
+ */
+struct ocfs2_slot_map {
+/*00*/	__le16 sm_slots[0];
+/*
+ * Actual on-disk size is one block.  OCFS2_MAX_SLOTS is 255,
+ * 255 * sizeof(__le16) == 512B, within the 512B block minimum blocksize.
+ */
+};
+
+struct ocfs2_extended_slot {
+/*00*/	__u8	es_valid;
+	__u8	es_reserved1[3];
+	__le32	es_node_num;
+/*10*/
+};
+
+/*
+ * The extended slot map, used when OCFS2_FEATURE_INCOMPAT_EXTENDED_SLOT_MAP
+ * is set.  It separates out the valid marker from the node number, and
+ * has room to grow.  Unlike the old slot map, this format is defined by
+ * i_size.
+ */
+struct ocfs2_slot_map_extended {
+/*00*/	struct ocfs2_extended_slot se_slots[0];
+/*
+ * Actual size is i_size of the slot_map system file.  It should
+ * match s_max_slots * sizeof(struct ocfs2_extended_slot)
+ */
+};
+
+struct ocfs2_cluster_info {
+/*00*/	__u8   ci_stack[OCFS2_STACK_LABEL_LEN];
+	__le32 ci_reserved;
+/*08*/	__u8   ci_cluster[OCFS2_CLUSTER_NAME_LEN];
+/*18*/
+};
+
+/*
  * On disk superblock for OCFS2
  * Note that it is contained inside an ocfs2_dinode, so all offsets
  * are relative to the start of ocfs2_dinode.id2.
@@ -506,7 +568,20 @@ struct ocfs2_super_block {
 					 * group header */
 /*50*/	__u8  s_label[OCFS2_MAX_VOL_LABEL_LEN];	/* Label for mounting, etc. */
 /*90*/	__u8  s_uuid[OCFS2_VOL_UUID_LEN];	/* 128-bit uuid */
-/*A0*/
+/*A0*/  struct ocfs2_cluster_info s_cluster_info; /* Selected userspace
+						     stack.  Only valid
+						     with INCOMPAT flag. */
+/*B8*/  __le64 s_reserved2[17];		/* Fill out superblock */
+/*140*/
+
+	/*
+	 * NOTE: As stated above, all offsets are relative to
+	 * ocfs2_dinode.id2, which is at 0xC0 in the inode.
+	 * 0xC0 + 0x140 = 0x200 or 512 bytes.  A superblock must fit within
+	 * our smallest blocksize, which is 512 bytes.  To ensure this,
+	 * we reserve the space in s_reserved2.  Anything past s_reserved2
+	 * will not be available on the smallest blocksize.
+	 */
 };
 
 /*
diff --git a/fs/ocfs2/ocfs2_lockid.h b/fs/ocfs2/ocfs2_lockid.h
index 86f3e3799c2..82c200f7a8f 100644
--- a/fs/ocfs2/ocfs2_lockid.h
+++ b/fs/ocfs2/ocfs2_lockid.h
@@ -100,7 +100,7 @@ static char *ocfs2_lock_type_strings[] = {
 static inline const char *ocfs2_lock_type_string(enum ocfs2_lock_type type)
 {
 #ifdef __KERNEL__
-	mlog_bug_on_msg(type >= OCFS2_NUM_LOCK_TYPES, "%d\n", type);
+	BUG_ON(type >= OCFS2_NUM_LOCK_TYPES);
 #endif
 	return ocfs2_lock_type_strings[type];
 }
diff --git a/fs/ocfs2/slot_map.c b/fs/ocfs2/slot_map.c
index 3a50ce555e6..bb5ff8939bf 100644
--- a/fs/ocfs2/slot_map.c
+++ b/fs/ocfs2/slot_map.c
@@ -42,81 +42,244 @@
 
 #include "buffer_head_io.h"
 
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-				    s16 global);
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-			      s16 slot_num,
-			      s16 node_num);
-
-/* post the slot information on disk into our slot_info struct. */
-void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
+
+struct ocfs2_slot {
+	int sl_valid;
+	unsigned int sl_node_num;
+};
+
+struct ocfs2_slot_info {
+	int si_extended;
+	int si_slots_per_block;
+	struct inode *si_inode;
+	unsigned int si_blocks;
+	struct buffer_head **si_bh;
+	unsigned int si_num_slots;
+	struct ocfs2_slot *si_slots;
+};
+
+
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+				    unsigned int node_num);
+
+static void ocfs2_invalidate_slot(struct ocfs2_slot_info *si,
+				  int slot_num)
+{
+	BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+	si->si_slots[slot_num].sl_valid = 0;
+}
+
+static void ocfs2_set_slot(struct ocfs2_slot_info *si,
+			   int slot_num, unsigned int node_num)
+{
+	BUG_ON((slot_num < 0) || (slot_num >= si->si_num_slots));
+
+	si->si_slots[slot_num].sl_valid = 1;
+	si->si_slots[slot_num].sl_node_num = node_num;
+}
+
+/* This version is for the extended slot map */
+static void ocfs2_update_slot_info_extended(struct ocfs2_slot_info *si)
+{
+	int b, i, slotno;
+	struct ocfs2_slot_map_extended *se;
+
+	slotno = 0;
+	for (b = 0; b < si->si_blocks; b++) {
+		se = (struct ocfs2_slot_map_extended *)si->si_bh[b]->b_data;
+		for (i = 0;
+		     (i < si->si_slots_per_block) &&
+		     (slotno < si->si_num_slots);
+		     i++, slotno++) {
+			if (se->se_slots[i].es_valid)
+				ocfs2_set_slot(si, slotno,
+					       le32_to_cpu(se->se_slots[i].es_node_num));
+			else
+				ocfs2_invalidate_slot(si, slotno);
+		}
+	}
+}
+
+/*
+ * Post the slot information on disk into our slot_info struct.
+ * Must be protected by osb_lock.
+ */
+static void ocfs2_update_slot_info_old(struct ocfs2_slot_info *si)
 {
 	int i;
-	__le16 *disk_info;
+	struct ocfs2_slot_map *sm;
 
-	/* we don't read the slot block here as ocfs2_super_lock
-	 * should've made sure we have the most recent copy. */
-	spin_lock(&si->si_lock);
-	disk_info = (__le16 *) si->si_bh->b_data;
+	sm = (struct ocfs2_slot_map *)si->si_bh[0]->b_data;
 
-	for (i = 0; i < si->si_size; i++)
-		si->si_global_node_nums[i] = le16_to_cpu(disk_info[i]);
+	for (i = 0; i < si->si_num_slots; i++) {
+		if (le16_to_cpu(sm->sm_slots[i]) == (u16)OCFS2_INVALID_SLOT)
+			ocfs2_invalidate_slot(si, i);
+		else
+			ocfs2_set_slot(si, i, le16_to_cpu(sm->sm_slots[i]));
+	}
+}
 
-	spin_unlock(&si->si_lock);
+static void ocfs2_update_slot_info(struct ocfs2_slot_info *si)
+{
+	/*
+	 * The slot data will have been refreshed when ocfs2_super_lock
+	 * was taken.
+	 */
+	if (si->si_extended)
+		ocfs2_update_slot_info_extended(si);
+	else
+		ocfs2_update_slot_info_old(si);
+}
+
+int ocfs2_refresh_slot_info(struct ocfs2_super *osb)
+{
+	int ret;
+	struct ocfs2_slot_info *si = osb->slot_info;
+
+	if (si == NULL)
+		return 0;
+
+	BUG_ON(si->si_blocks == 0);
+	BUG_ON(si->si_bh == NULL);
+
+	mlog(0, "Refreshing slot map, reading %u block(s)\n",
+	     si->si_blocks);
+
+	/*
+	 * We pass -1 as blocknr because we expect all of si->si_bh to
+	 * be !NULL.  Thus, ocfs2_read_blocks() will ignore blocknr.  If
+	 * this is not true, the read of -1 (UINT64_MAX) will fail.
+	 */
+	ret = ocfs2_read_blocks(osb, -1, si->si_blocks, si->si_bh, 0,
+				si->si_inode);
+	if (ret == 0) {
+		spin_lock(&osb->osb_lock);
+		ocfs2_update_slot_info(si);
+		spin_unlock(&osb->osb_lock);
+	}
+
+	return ret;
 }
 
 /* post the our slot info stuff into it's destination bh and write it
  * out. */
-int ocfs2_update_disk_slots(struct ocfs2_super *osb,
-			    struct ocfs2_slot_info *si)
+static void ocfs2_update_disk_slot_extended(struct ocfs2_slot_info *si,
+					    int slot_num,
+					    struct buffer_head **bh)
 {
-	int status, i;
-	__le16 *disk_info = (__le16 *) si->si_bh->b_data;
+	int blkind = slot_num / si->si_slots_per_block;
+	int slotno = slot_num % si->si_slots_per_block;
+	struct ocfs2_slot_map_extended *se;
+
+	BUG_ON(blkind >= si->si_blocks);
+
+	se = (struct ocfs2_slot_map_extended *)si->si_bh[blkind]->b_data;
+	se->se_slots[slotno].es_valid = si->si_slots[slot_num].sl_valid;
+	if (si->si_slots[slot_num].sl_valid)
+		se->se_slots[slotno].es_node_num =
+			cpu_to_le32(si->si_slots[slot_num].sl_node_num);
+	*bh = si->si_bh[blkind];
+}
 
-	spin_lock(&si->si_lock);
-	for (i = 0; i < si->si_size; i++)
-		disk_info[i] = cpu_to_le16(si->si_global_node_nums[i]);
-	spin_unlock(&si->si_lock);
+static void ocfs2_update_disk_slot_old(struct ocfs2_slot_info *si,
+				       int slot_num,
+				       struct buffer_head **bh)
+{
+	int i;
+	struct ocfs2_slot_map *sm;
+
+	sm = (struct ocfs2_slot_map *)si->si_bh[0]->b_data;
+	for (i = 0; i < si->si_num_slots; i++) {
+		if (si->si_slots[i].sl_valid)
+			sm->sm_slots[i] =
+				cpu_to_le16(si->si_slots[i].sl_node_num);
+		else
+			sm->sm_slots[i] = cpu_to_le16(OCFS2_INVALID_SLOT);
+	}
+	*bh = si->si_bh[0];
+}
+
+static int ocfs2_update_disk_slot(struct ocfs2_super *osb,
+				  struct ocfs2_slot_info *si,
+				  int slot_num)
+{
+	int status;
+	struct buffer_head *bh;
+
+	spin_lock(&osb->osb_lock);
+	if (si->si_extended)
+		ocfs2_update_disk_slot_extended(si, slot_num, &bh);
+	else
+		ocfs2_update_disk_slot_old(si, slot_num, &bh);
+	spin_unlock(&osb->osb_lock);
 
-	status = ocfs2_write_block(osb, si->si_bh, si->si_inode);
+	status = ocfs2_write_block(osb, bh, si->si_inode);
 	if (status < 0)
 		mlog_errno(status);
 
 	return status;
 }
 
-/* try to find global node in the slot info. Returns
- * OCFS2_INVALID_SLOT if nothing is found. */
-static s16 __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-				    s16 global)
+/*
+ * Calculate how many bytes are needed by the slot map.  Returns
+ * an error if the slot map file is too small.
+ */
+static int ocfs2_slot_map_physical_size(struct ocfs2_super *osb,
+					struct inode *inode,
+					unsigned long long *bytes)
 {
-	int i;
-	s16 ret = OCFS2_INVALID_SLOT;
+	unsigned long long bytes_needed;
+
+	if (ocfs2_uses_extended_slot_map(osb)) {
+		bytes_needed = osb->max_slots *
+			sizeof(struct ocfs2_extended_slot);
+	} else {
+		bytes_needed = osb->max_slots * sizeof(__le16);
+	}
+	if (bytes_needed > i_size_read(inode)) {
+		mlog(ML_ERROR,
+		     "Slot map file is too small!  (size %llu, needed %llu)\n",
+		     i_size_read(inode), bytes_needed);
+		return -ENOSPC;
+	}
+
+	*bytes = bytes_needed;
+	return 0;
+}
+
+/* try to find global node in the slot info. Returns -ENOENT
+ * if nothing is found. */
+static int __ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
+				    unsigned int node_num)
+{
+	int i, ret = -ENOENT;
 
 	for(i = 0; i < si->si_num_slots; i++) {
-		if (global == si->si_global_node_nums[i]) {
-			ret = (s16) i;
+		if (si->si_slots[i].sl_valid &&
+		    (node_num == si->si_slots[i].sl_node_num)) {
+			ret = i;
 			break;
 		}
 	}
+
 	return ret;
 }
 
-static s16 __ocfs2_find_empty_slot(struct ocfs2_slot_info *si, s16 preferred)
+static int __ocfs2_find_empty_slot(struct ocfs2_slot_info *si,
+				   int preferred)
 {
-	int i;
-	s16 ret = OCFS2_INVALID_SLOT;
+	int i, ret = -ENOSPC;
 
-	if (preferred >= 0 && preferred < si->si_num_slots) {
-		if (OCFS2_INVALID_SLOT == si->si_global_node_nums[preferred]) {
+	if ((preferred >= 0) && (preferred < si->si_num_slots)) {
+		if (!si->si_slots[preferred].sl_valid) {
 			ret = preferred;
 			goto out;
 		}
 	}
 
 	for(i = 0; i < si->si_num_slots; i++) {
-		if (OCFS2_INVALID_SLOT == si->si_global_node_nums[i]) {
-			ret = (s16) i;
+		if (!si->si_slots[i].sl_valid) {
+			ret = i;
 			break;
 		}
 	}
@@ -124,58 +287,155 @@ out:
 	return ret;
 }
 
-s16 ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-			   s16 global)
+int ocfs2_node_num_to_slot(struct ocfs2_super *osb, unsigned int node_num)
 {
-	s16 ret;
+	int slot;
+	struct ocfs2_slot_info *si = osb->slot_info;
 
-	spin_lock(&si->si_lock);
-	ret = __ocfs2_node_num_to_slot(si, global);
-	spin_unlock(&si->si_lock);
-	return ret;
+	spin_lock(&osb->osb_lock);
+	slot = __ocfs2_node_num_to_slot(si, node_num);
+	spin_unlock(&osb->osb_lock);
+
+	return slot;
+}
+
+int ocfs2_slot_to_node_num_locked(struct ocfs2_super *osb, int slot_num,
+				  unsigned int *node_num)
+{
+	struct ocfs2_slot_info *si = osb->slot_info;
+
+	assert_spin_locked(&osb->osb_lock);
+
+	BUG_ON(slot_num < 0);
+	BUG_ON(slot_num > osb->max_slots);
+
+	if (!si->si_slots[slot_num].sl_valid)
+		return -ENOENT;
+
+	*node_num = si->si_slots[slot_num].sl_node_num;
+	return 0;
 }
 
-static void __ocfs2_fill_slot(struct ocfs2_slot_info *si,
-			      s16 slot_num,
-			      s16 node_num)
+static void __ocfs2_free_slot_info(struct ocfs2_slot_info *si)
 {
-	BUG_ON(slot_num == OCFS2_INVALID_SLOT);
-	BUG_ON(slot_num >= si->si_num_slots);
-	BUG_ON((node_num != O2NM_INVALID_NODE_NUM) &&
-	       (node_num >= O2NM_MAX_NODES));
+	unsigned int i;
+
+	if (si == NULL)
+		return;
+
+	if (si->si_inode)
+		iput(si->si_inode);
+	if (si->si_bh) {
+		for (i = 0; i < si->si_blocks; i++) {
+			if (si->si_bh[i]) {
+				brelse(si->si_bh[i]);
+				si->si_bh[i] = NULL;
+			}
+		}
+		kfree(si->si_bh);
+	}
 
-	si->si_global_node_nums[slot_num] = node_num;
+	kfree(si);
 }
 
-void ocfs2_clear_slot(struct ocfs2_slot_info *si,
-		      s16 slot_num)
+int ocfs2_clear_slot(struct ocfs2_super *osb, int slot_num)
 {
-	spin_lock(&si->si_lock);
-	__ocfs2_fill_slot(si, slot_num, OCFS2_INVALID_SLOT);
-	spin_unlock(&si->si_lock);
+	struct ocfs2_slot_info *si = osb->slot_info;
+
+	if (si == NULL)
+		return 0;
+
+	spin_lock(&osb->osb_lock);
+	ocfs2_invalidate_slot(si, slot_num);
+	spin_unlock(&osb->osb_lock);
+
+	return ocfs2_update_disk_slot(osb, osb->slot_info, slot_num);
 }
 
-int ocfs2_init_slot_info(struct ocfs2_super *osb)
+static int ocfs2_map_slot_buffers(struct ocfs2_super *osb,
+				  struct ocfs2_slot_info *si)
 {
-	int status, i;
+	int status = 0;
 	u64 blkno;
+	unsigned long long blocks, bytes;
+	unsigned int i;
+	struct buffer_head *bh;
+
+	status = ocfs2_slot_map_physical_size(osb, si->si_inode, &bytes);
+	if (status)
+		goto bail;
+
+	blocks = ocfs2_blocks_for_bytes(si->si_inode->i_sb, bytes);
+	BUG_ON(blocks > UINT_MAX);
+	si->si_blocks = blocks;
+	if (!si->si_blocks)
+		goto bail;
+
+	if (si->si_extended)
+		si->si_slots_per_block =
+			(osb->sb->s_blocksize /
+			 sizeof(struct ocfs2_extended_slot));
+	else
+		si->si_slots_per_block = osb->sb->s_blocksize / sizeof(__le16);
+
+	/* The size checks above should ensure this */
+	BUG_ON((osb->max_slots / si->si_slots_per_block) > blocks);
+
+	mlog(0, "Slot map needs %u buffers for %llu bytes\n",
+	     si->si_blocks, bytes);
+
+	si->si_bh = kzalloc(sizeof(struct buffer_head *) * si->si_blocks,
+			    GFP_KERNEL);
+	if (!si->si_bh) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
+	for (i = 0; i < si->si_blocks; i++) {
+		status = ocfs2_extent_map_get_blocks(si->si_inode, i,
+						     &blkno, NULL, NULL);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		mlog(0, "Reading slot map block %u at %llu\n", i,
+		     (unsigned long long)blkno);
+
+		bh = NULL;  /* Acquire a fresh bh */
+		status = ocfs2_read_block(osb, blkno, &bh, 0, si->si_inode);
+		if (status < 0) {
+			mlog_errno(status);
+			goto bail;
+		}
+
+		si->si_bh[i] = bh;
+	}
+
+bail:
+	return status;
+}
+
+int ocfs2_init_slot_info(struct ocfs2_super *osb)
+{
+	int status;
 	struct inode *inode = NULL;
-	struct buffer_head *bh = NULL;
 	struct ocfs2_slot_info *si;
 
-	si = kzalloc(sizeof(struct ocfs2_slot_info), GFP_KERNEL);
+	si = kzalloc(sizeof(struct ocfs2_slot_info) +
+		     (sizeof(struct ocfs2_slot) * osb->max_slots),
+		     GFP_KERNEL);
 	if (!si) {
 		status = -ENOMEM;
 		mlog_errno(status);
 		goto bail;
 	}
 
-	spin_lock_init(&si->si_lock);
+	si->si_extended = ocfs2_uses_extended_slot_map(osb);
 	si->si_num_slots = osb->max_slots;
-	si->si_size = OCFS2_MAX_SLOTS;
-
-	for(i = 0; i < si->si_num_slots; i++)
-		si->si_global_node_nums[i] = OCFS2_INVALID_SLOT;
+	si->si_slots = (struct ocfs2_slot *)((char *)si +
+					     sizeof(struct ocfs2_slot_info));
 
 	inode = ocfs2_get_system_file_inode(osb, SLOT_MAP_SYSTEM_INODE,
 					    OCFS2_INVALID_SLOT);
@@ -185,61 +445,53 @@ int ocfs2_init_slot_info(struct ocfs2_super *osb)
 		goto bail;
 	}
 
-	status = ocfs2_extent_map_get_blocks(inode, 0ULL, &blkno, NULL, NULL);
-	if (status < 0) {
-		mlog_errno(status);
-		goto bail;
-	}
-
-	status = ocfs2_read_block(osb, blkno, &bh, 0, inode);
+	si->si_inode = inode;
+	status = ocfs2_map_slot_buffers(osb, si);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}
 
-	si->si_inode = inode;
-	si->si_bh = bh;
-	osb->slot_info = si;
+	osb->slot_info = (struct ocfs2_slot_info *)si;
 bail:
 	if (status < 0 && si)
-		ocfs2_free_slot_info(si);
+		__ocfs2_free_slot_info(si);
 
 	return status;
 }
 
-void ocfs2_free_slot_info(struct ocfs2_slot_info *si)
+void ocfs2_free_slot_info(struct ocfs2_super *osb)
 {
-	if (si->si_inode)
-		iput(si->si_inode);
-	if (si->si_bh)
-		brelse(si->si_bh);
-	kfree(si);
+	struct ocfs2_slot_info *si = osb->slot_info;
+
+	osb->slot_info = NULL;
+	__ocfs2_free_slot_info(si);
 }
 
 int ocfs2_find_slot(struct ocfs2_super *osb)
 {
 	int status;
-	s16 slot;
+	int slot;
 	struct ocfs2_slot_info *si;
 
 	mlog_entry_void();
 
 	si = osb->slot_info;
 
+	spin_lock(&osb->osb_lock);
 	ocfs2_update_slot_info(si);
 
-	spin_lock(&si->si_lock);
 	/* search for ourselves first and take the slot if it already
 	 * exists. Perhaps we need to mark this in a variable for our
 	 * own journal recovery? Possibly not, though we certainly
 	 * need to warn to the user */
 	slot = __ocfs2_node_num_to_slot(si, osb->node_num);
-	if (slot == OCFS2_INVALID_SLOT) {
+	if (slot < 0) {
 		/* if no slot yet, then just take 1st available
 		 * one. */
 		slot = __ocfs2_find_empty_slot(si, osb->preferred_slot);
-		if (slot == OCFS2_INVALID_SLOT) {
-			spin_unlock(&si->si_lock);
+		if (slot < 0) {
+			spin_unlock(&osb->osb_lock);
 			mlog(ML_ERROR, "no free slots available!\n");
 			status = -EINVAL;
 			goto bail;
@@ -248,13 +500,13 @@ int ocfs2_find_slot(struct ocfs2_super *osb)
 		mlog(ML_NOTICE, "slot %d is already allocated to this node!\n",
 		     slot);
 
-	__ocfs2_fill_slot(si, slot, osb->node_num);
+	ocfs2_set_slot(si, slot, osb->node_num);
 	osb->slot_num = slot;
-	spin_unlock(&si->si_lock);
+	spin_unlock(&osb->osb_lock);
 
 	mlog(0, "taking node slot %d\n", osb->slot_num);
 
-	status = ocfs2_update_disk_slots(osb, si);
+	status = ocfs2_update_disk_slot(osb, si, osb->slot_num);
 	if (status < 0)
 		mlog_errno(status);
 
@@ -265,27 +517,27 @@ bail:
 
 void ocfs2_put_slot(struct ocfs2_super *osb)
 {
-	int status;
+	int status, slot_num;
 	struct ocfs2_slot_info *si = osb->slot_info;
 
 	if (!si)
 		return;
 
+	spin_lock(&osb->osb_lock);
 	ocfs2_update_slot_info(si);
 
-	spin_lock(&si->si_lock);
-	__ocfs2_fill_slot(si, osb->slot_num, OCFS2_INVALID_SLOT);
+	slot_num = osb->slot_num;
+	ocfs2_invalidate_slot(si, osb->slot_num);
 	osb->slot_num = OCFS2_INVALID_SLOT;
-	spin_unlock(&si->si_lock);
+	spin_unlock(&osb->osb_lock);
 
-	status = ocfs2_update_disk_slots(osb, si);
+	status = ocfs2_update_disk_slot(osb, si, slot_num);
 	if (status < 0) {
 		mlog_errno(status);
 		goto bail;
 	}
 
 bail:
-	osb->slot_info = NULL;
-	ocfs2_free_slot_info(si);
+	ocfs2_free_slot_info(osb);
 }
 
diff --git a/fs/ocfs2/slot_map.h b/fs/ocfs2/slot_map.h
index 1025872aaad..601c95fd700 100644
--- a/fs/ocfs2/slot_map.h
+++ b/fs/ocfs2/slot_map.h
@@ -27,38 +27,18 @@
 #ifndef SLOTMAP_H
 #define SLOTMAP_H
 
-struct ocfs2_slot_info {
-	spinlock_t si_lock;
-
-       	struct inode *si_inode;
-	struct buffer_head *si_bh;
-	unsigned int si_num_slots;
-	unsigned int si_size;
-	s16 si_global_node_nums[OCFS2_MAX_SLOTS];
-};
-
 int ocfs2_init_slot_info(struct ocfs2_super *osb);
-void ocfs2_free_slot_info(struct ocfs2_slot_info *si);
+void ocfs2_free_slot_info(struct ocfs2_super *osb);
 
 int ocfs2_find_slot(struct ocfs2_super *osb);
 void ocfs2_put_slot(struct ocfs2_super *osb);
 
-void ocfs2_update_slot_info(struct ocfs2_slot_info *si);
-int ocfs2_update_disk_slots(struct ocfs2_super *osb,
-			    struct ocfs2_slot_info *si);
-
-s16 ocfs2_node_num_to_slot(struct ocfs2_slot_info *si,
-			   s16 global);
-void ocfs2_clear_slot(struct ocfs2_slot_info *si,
-		      s16 slot_num);
+int ocfs2_refresh_slot_info(struct ocfs2_super *osb);
 
-static inline int ocfs2_is_empty_slot(struct ocfs2_slot_info *si,
-				      int slot_num)
-{
-	BUG_ON(slot_num == OCFS2_INVALID_SLOT);
-	assert_spin_locked(&si->si_lock);
+int ocfs2_node_num_to_slot(struct ocfs2_super *osb, unsigned int node_num);
+int ocfs2_slot_to_node_num_locked(struct ocfs2_super *osb, int slot_num,
+				  unsigned int *node_num);
 
-	return si->si_global_node_nums[slot_num] == OCFS2_INVALID_SLOT;
-}
+int ocfs2_clear_slot(struct ocfs2_super *osb, int slot_num);
 
 #endif
diff --git a/fs/ocfs2/stack_o2cb.c b/fs/ocfs2/stack_o2cb.c
new file mode 100644
index 00000000000..ac1d74c63bf
--- /dev/null
+++ b/fs/ocfs2/stack_o2cb.c
@@ -0,0 +1,420 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stack_o2cb.c
+ *
+ * Code which interfaces ocfs2 with the o2cb stack.
+ *
+ * Copyright (C) 2007 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, version 2.
+ *
+ * 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.
+ */
+
+#include <linux/crc32.h>
+#include <linux/module.h>
+
+/* Needed for AOP_TRUNCATED_PAGE in mlog_errno() */
+#include <linux/fs.h>
+
+#include "cluster/masklog.h"
+#include "cluster/nodemanager.h"
+#include "cluster/heartbeat.h"
+
+#include "stackglue.h"
+
+struct o2dlm_private {
+	struct dlm_eviction_cb op_eviction_cb;
+};
+
+static struct ocfs2_stack_plugin o2cb_stack;
+
+/* These should be identical */
+#if (DLM_LOCK_IV != LKM_IVMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_NL != LKM_NLMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_CR != LKM_CRMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_CW != LKM_CWMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_PR != LKM_PRMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_PW != LKM_PWMODE)
+# error Lock modes do not match
+#endif
+#if (DLM_LOCK_EX != LKM_EXMODE)
+# error Lock modes do not match
+#endif
+static inline int mode_to_o2dlm(int mode)
+{
+	BUG_ON(mode > LKM_MAXMODE);
+
+	return mode;
+}
+
+#define map_flag(_generic, _o2dlm)		\
+	if (flags & (_generic)) {		\
+		flags &= ~(_generic);		\
+		o2dlm_flags |= (_o2dlm);	\
+	}
+static int flags_to_o2dlm(u32 flags)
+{
+	int o2dlm_flags = 0;
+
+	map_flag(DLM_LKF_NOQUEUE, LKM_NOQUEUE);
+	map_flag(DLM_LKF_CANCEL, LKM_CANCEL);
+	map_flag(DLM_LKF_CONVERT, LKM_CONVERT);
+	map_flag(DLM_LKF_VALBLK, LKM_VALBLK);
+	map_flag(DLM_LKF_IVVALBLK, LKM_INVVALBLK);
+	map_flag(DLM_LKF_ORPHAN, LKM_ORPHAN);
+	map_flag(DLM_LKF_FORCEUNLOCK, LKM_FORCE);
+	map_flag(DLM_LKF_TIMEOUT, LKM_TIMEOUT);
+	map_flag(DLM_LKF_LOCAL, LKM_LOCAL);
+
+	/* map_flag() should have cleared every flag passed in */
+	BUG_ON(flags != 0);
+
+	return o2dlm_flags;
+}
+#undef map_flag
+
+/*
+ * Map an o2dlm status to standard errno values.
+ *
+ * o2dlm only uses a handful of these, and returns even fewer to the
+ * caller. Still, we try to assign sane values to each error.
+ *
+ * The following value pairs have special meanings to dlmglue, thus
+ * the right hand side needs to stay unique - never duplicate the
+ * mapping elsewhere in the table!
+ *
+ * DLM_NORMAL:		0
+ * DLM_NOTQUEUED:	-EAGAIN
+ * DLM_CANCELGRANT:	-EBUSY
+ * DLM_CANCEL:		-DLM_ECANCEL
+ */
+/* Keep in sync with dlmapi.h */
+static int status_map[] = {
+	[DLM_NORMAL]			= 0,		/* Success */
+	[DLM_GRANTED]			= -EINVAL,
+	[DLM_DENIED]			= -EACCES,
+	[DLM_DENIED_NOLOCKS]		= -EACCES,
+	[DLM_WORKING]			= -EACCES,
+	[DLM_BLOCKED]			= -EINVAL,
+	[DLM_BLOCKED_ORPHAN]		= -EINVAL,
+	[DLM_DENIED_GRACE_PERIOD]	= -EACCES,
+	[DLM_SYSERR]			= -ENOMEM,	/* It is what it is */
+	[DLM_NOSUPPORT]			= -EPROTO,
+	[DLM_CANCELGRANT]		= -EBUSY,	/* Cancel after grant */
+	[DLM_IVLOCKID]			= -EINVAL,
+	[DLM_SYNC]			= -EINVAL,
+	[DLM_BADTYPE]			= -EINVAL,
+	[DLM_BADRESOURCE]		= -EINVAL,
+	[DLM_MAXHANDLES]		= -ENOMEM,
+	[DLM_NOCLINFO]			= -EINVAL,
+	[DLM_NOLOCKMGR]			= -EINVAL,
+	[DLM_NOPURGED]			= -EINVAL,
+	[DLM_BADARGS]			= -EINVAL,
+	[DLM_VOID]			= -EINVAL,
+	[DLM_NOTQUEUED]			= -EAGAIN,	/* Trylock failed */
+	[DLM_IVBUFLEN]			= -EINVAL,
+	[DLM_CVTUNGRANT]		= -EPERM,
+	[DLM_BADPARAM]			= -EINVAL,
+	[DLM_VALNOTVALID]		= -EINVAL,
+	[DLM_REJECTED]			= -EPERM,
+	[DLM_ABORT]			= -EINVAL,
+	[DLM_CANCEL]			= -DLM_ECANCEL,	/* Successful cancel */
+	[DLM_IVRESHANDLE]		= -EINVAL,
+	[DLM_DEADLOCK]			= -EDEADLK,
+	[DLM_DENIED_NOASTS]		= -EINVAL,
+	[DLM_FORWARD]			= -EINVAL,
+	[DLM_TIMEOUT]			= -ETIMEDOUT,
+	[DLM_IVGROUPID]			= -EINVAL,
+	[DLM_VERS_CONFLICT]		= -EOPNOTSUPP,
+	[DLM_BAD_DEVICE_PATH]		= -ENOENT,
+	[DLM_NO_DEVICE_PERMISSION]	= -EPERM,
+	[DLM_NO_CONTROL_DEVICE]		= -ENOENT,
+	[DLM_RECOVERING]		= -ENOTCONN,
+	[DLM_MIGRATING]			= -ERESTART,
+	[DLM_MAXSTATS]			= -EINVAL,
+};
+
+static int dlm_status_to_errno(enum dlm_status status)
+{
+	BUG_ON(status > (sizeof(status_map) / sizeof(status_map[0])));
+
+	return status_map[status];
+}
+
+static void o2dlm_lock_ast_wrapper(void *astarg)
+{
+	BUG_ON(o2cb_stack.sp_proto == NULL);
+
+	o2cb_stack.sp_proto->lp_lock_ast(astarg);
+}
+
+static void o2dlm_blocking_ast_wrapper(void *astarg, int level)
+{
+	BUG_ON(o2cb_stack.sp_proto == NULL);
+
+	o2cb_stack.sp_proto->lp_blocking_ast(astarg, level);
+}
+
+static void o2dlm_unlock_ast_wrapper(void *astarg, enum dlm_status status)
+{
+	int error = dlm_status_to_errno(status);
+
+	BUG_ON(o2cb_stack.sp_proto == NULL);
+
+	/*
+	 * In o2dlm, you can get both the lock_ast() for the lock being
+	 * granted and the unlock_ast() for the CANCEL failing.  A
+	 * successful cancel sends DLM_NORMAL here.  If the
+	 * lock grant happened before the cancel arrived, you get
+	 * DLM_CANCELGRANT.
+	 *
+	 * There's no need for the double-ast.  If we see DLM_CANCELGRANT,
+	 * we just ignore it.  We expect the lock_ast() to handle the
+	 * granted lock.
+	 */
+	if (status == DLM_CANCELGRANT)
+		return;
+
+	o2cb_stack.sp_proto->lp_unlock_ast(astarg, error);
+}
+
+static int o2cb_dlm_lock(struct ocfs2_cluster_connection *conn,
+			 int mode,
+			 union ocfs2_dlm_lksb *lksb,
+			 u32 flags,
+			 void *name,
+			 unsigned int namelen,
+			 void *astarg)
+{
+	enum dlm_status status;
+	int o2dlm_mode = mode_to_o2dlm(mode);
+	int o2dlm_flags = flags_to_o2dlm(flags);
+	int ret;
+
+	status = dlmlock(conn->cc_lockspace, o2dlm_mode, &lksb->lksb_o2dlm,
+			 o2dlm_flags, name, namelen,
+			 o2dlm_lock_ast_wrapper, astarg,
+			 o2dlm_blocking_ast_wrapper);
+	ret = dlm_status_to_errno(status);
+	return ret;
+}
+
+static int o2cb_dlm_unlock(struct ocfs2_cluster_connection *conn,
+			   union ocfs2_dlm_lksb *lksb,
+			   u32 flags,
+			   void *astarg)
+{
+	enum dlm_status status;
+	int o2dlm_flags = flags_to_o2dlm(flags);
+	int ret;
+
+	status = dlmunlock(conn->cc_lockspace, &lksb->lksb_o2dlm,
+			   o2dlm_flags, o2dlm_unlock_ast_wrapper, astarg);
+	ret = dlm_status_to_errno(status);
+	return ret;
+}
+
+static int o2cb_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+	return dlm_status_to_errno(lksb->lksb_o2dlm.status);
+}
+
+static void *o2cb_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+	return (void *)(lksb->lksb_o2dlm.lvb);
+}
+
+static void o2cb_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+	dlm_print_one_lock(lksb->lksb_o2dlm.lockid);
+}
+
+/*
+ * Called from the dlm when it's about to evict a node. This is how the
+ * classic stack signals node death.
+ */
+static void o2dlm_eviction_cb(int node_num, void *data)
+{
+	struct ocfs2_cluster_connection *conn = data;
+
+	mlog(ML_NOTICE, "o2dlm has evicted node %d from group %.*s\n",
+	     node_num, conn->cc_namelen, conn->cc_name);
+
+	conn->cc_recovery_handler(node_num, conn->cc_recovery_data);
+}
+
+static int o2cb_cluster_connect(struct ocfs2_cluster_connection *conn)
+{
+	int rc = 0;
+	u32 dlm_key;
+	struct dlm_ctxt *dlm;
+	struct o2dlm_private *priv;
+	struct dlm_protocol_version dlm_version;
+
+	BUG_ON(conn == NULL);
+	BUG_ON(o2cb_stack.sp_proto == NULL);
+
+	/* for now we only have one cluster/node, make sure we see it
+	 * in the heartbeat universe */
+	if (!o2hb_check_local_node_heartbeating()) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	priv = kzalloc(sizeof(struct o2dlm_private), GFP_KERNEL);
+	if (!priv) {
+		rc = -ENOMEM;
+		goto out_free;
+	}
+
+	/* This just fills the structure in.  It is safe to pass conn. */
+	dlm_setup_eviction_cb(&priv->op_eviction_cb, o2dlm_eviction_cb,
+			      conn);
+
+	conn->cc_private = priv;
+
+	/* used by the dlm code to make message headers unique, each
+	 * node in this domain must agree on this. */
+	dlm_key = crc32_le(0, conn->cc_name, conn->cc_namelen);
+	dlm_version.pv_major = conn->cc_version.pv_major;
+	dlm_version.pv_minor = conn->cc_version.pv_minor;
+
+	dlm = dlm_register_domain(conn->cc_name, dlm_key, &dlm_version);
+	if (IS_ERR(dlm)) {
+		rc = PTR_ERR(dlm);
+		mlog_errno(rc);
+		goto out_free;
+	}
+
+	conn->cc_version.pv_major = dlm_version.pv_major;
+	conn->cc_version.pv_minor = dlm_version.pv_minor;
+	conn->cc_lockspace = dlm;
+
+	dlm_register_eviction_cb(dlm, &priv->op_eviction_cb);
+
+out_free:
+	if (rc && conn->cc_private)
+		kfree(conn->cc_private);
+
+out:
+	return rc;
+}
+
+static int o2cb_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+				   int hangup_pending)
+{
+	struct dlm_ctxt *dlm = conn->cc_lockspace;
+	struct o2dlm_private *priv = conn->cc_private;
+
+	dlm_unregister_eviction_cb(&priv->op_eviction_cb);
+	conn->cc_private = NULL;
+	kfree(priv);
+
+	dlm_unregister_domain(dlm);
+	conn->cc_lockspace = NULL;
+
+	return 0;
+}
+
+static void o2hb_stop(const char *group)
+{
+	int ret;
+	char *argv[5], *envp[3];
+
+	argv[0] = (char *)o2nm_get_hb_ctl_path();
+	argv[1] = "-K";
+	argv[2] = "-u";
+	argv[3] = (char *)group;
+	argv[4] = NULL;
+
+	mlog(0, "Run: %s %s %s %s\n", argv[0], argv[1], argv[2], argv[3]);
+
+	/* minimal command environment taken from cpu_run_sbin_hotplug */
+	envp[0] = "HOME=/";
+	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+	envp[2] = NULL;
+
+	ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
+	if (ret < 0)
+		mlog_errno(ret);
+}
+
+/*
+ * Hangup is a hack for tools compatibility.  Older ocfs2-tools software
+ * expects the filesystem to call "ocfs2_hb_ctl" during unmount.  This
+ * happens regardless of whether the DLM got started, so we can't do it
+ * in ocfs2_cluster_disconnect().  We bring the o2hb_stop() function into
+ * the glue and provide a "hangup" API for super.c to call.
+ *
+ * Other stacks will eventually provide a NULL ->hangup() pointer.
+ */
+static void o2cb_cluster_hangup(const char *group, int grouplen)
+{
+	o2hb_stop(group);
+}
+
+static int o2cb_cluster_this_node(unsigned int *node)
+{
+	int node_num;
+
+	node_num = o2nm_this_node();
+	if (node_num == O2NM_INVALID_NODE_NUM)
+		return -ENOENT;
+
+	if (node_num >= O2NM_MAX_NODES)
+		return -EOVERFLOW;
+
+	*node = node_num;
+	return 0;
+}
+
+struct ocfs2_stack_operations o2cb_stack_ops = {
+	.connect	= o2cb_cluster_connect,
+	.disconnect	= o2cb_cluster_disconnect,
+	.hangup		= o2cb_cluster_hangup,
+	.this_node	= o2cb_cluster_this_node,
+	.dlm_lock	= o2cb_dlm_lock,
+	.dlm_unlock	= o2cb_dlm_unlock,
+	.lock_status	= o2cb_dlm_lock_status,
+	.lock_lvb	= o2cb_dlm_lvb,
+	.dump_lksb	= o2cb_dump_lksb,
+};
+
+static struct ocfs2_stack_plugin o2cb_stack = {
+	.sp_name	= "o2cb",
+	.sp_ops		= &o2cb_stack_ops,
+	.sp_owner	= THIS_MODULE,
+};
+
+static int __init o2cb_stack_init(void)
+{
+	return ocfs2_stack_glue_register(&o2cb_stack);
+}
+
+static void __exit o2cb_stack_exit(void)
+{
+	ocfs2_stack_glue_unregister(&o2cb_stack);
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for the classic o2cb stack");
+MODULE_LICENSE("GPL");
+module_init(o2cb_stack_init);
+module_exit(o2cb_stack_exit);
diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
new file mode 100644
index 00000000000..7428663f9cb
--- /dev/null
+++ b/fs/ocfs2/stack_user.c
@@ -0,0 +1,883 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stack_user.c
+ *
+ * Code which interfaces ocfs2 with fs/dlm and a userspace stack.
+ *
+ * Copyright (C) 2007 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, version 2.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/mutex.h>
+#include <linux/reboot.h>
+#include <asm/uaccess.h>
+
+#include "ocfs2.h"  /* For struct ocfs2_lock_res */
+#include "stackglue.h"
+
+
+/*
+ * The control protocol starts with a handshake.  Until the handshake
+ * is complete, the control device will fail all write(2)s.
+ *
+ * The handshake is simple.  First, the client reads until EOF.  Each line
+ * of output is a supported protocol tag.  All protocol tags are a single
+ * character followed by a two hex digit version number.  Currently the
+ * only things supported is T01, for "Text-base version 0x01".  Next, the
+ * client writes the version they would like to use, including the newline.
+ * Thus, the protocol tag is 'T01\n'.  If the version tag written is
+ * unknown, -EINVAL is returned.  Once the negotiation is complete, the
+ * client can start sending messages.
+ *
+ * The T01 protocol has three messages.  First is the "SETN" message.
+ * It has the following syntax:
+ *
+ *  SETN<space><8-char-hex-nodenum><newline>
+ *
+ * This is 14 characters.
+ *
+ * The "SETN" message must be the first message following the protocol.
+ * It tells ocfs2_control the local node number.
+ *
+ * Next comes the "SETV" message.  It has the following syntax:
+ *
+ *  SETV<space><2-char-hex-major><space><2-char-hex-minor><newline>
+ *
+ * This is 11 characters.
+ *
+ * The "SETV" message sets the filesystem locking protocol version as
+ * negotiated by the client.  The client negotiates based on the maximum
+ * version advertised in /sys/fs/ocfs2/max_locking_protocol.  The major
+ * number from the "SETV" message must match
+ * user_stack.sp_proto->lp_max_version.pv_major, and the minor number
+ * must be less than or equal to ...->lp_max_version.pv_minor.
+ *
+ * Once this information has been set, mounts will be allowed.  From this
+ * point on, the "DOWN" message can be sent for node down notification.
+ * It has the following syntax:
+ *
+ *  DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline>
+ *
+ * eg:
+ *
+ *  DOWN 632A924FDD844190BDA93C0DF6B94899 00000001\n
+ *
+ * This is 47 characters.
+ */
+
+/*
+ * Whether or not the client has done the handshake.
+ * For now, we have just one protocol version.
+ */
+#define OCFS2_CONTROL_PROTO			"T01\n"
+#define OCFS2_CONTROL_PROTO_LEN			4
+
+/* Handshake states */
+#define OCFS2_CONTROL_HANDSHAKE_INVALID		(0)
+#define OCFS2_CONTROL_HANDSHAKE_READ		(1)
+#define OCFS2_CONTROL_HANDSHAKE_PROTOCOL	(2)
+#define OCFS2_CONTROL_HANDSHAKE_VALID		(3)
+
+/* Messages */
+#define OCFS2_CONTROL_MESSAGE_OP_LEN		4
+#define OCFS2_CONTROL_MESSAGE_SETNODE_OP	"SETN"
+#define OCFS2_CONTROL_MESSAGE_SETNODE_TOTAL_LEN	14
+#define OCFS2_CONTROL_MESSAGE_SETVERSION_OP	"SETV"
+#define OCFS2_CONTROL_MESSAGE_SETVERSION_TOTAL_LEN	11
+#define OCFS2_CONTROL_MESSAGE_DOWN_OP		"DOWN"
+#define OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN	47
+#define OCFS2_TEXT_UUID_LEN			32
+#define OCFS2_CONTROL_MESSAGE_VERNUM_LEN	2
+#define OCFS2_CONTROL_MESSAGE_NODENUM_LEN	8
+
+/*
+ * ocfs2_live_connection is refcounted because the filesystem and
+ * miscdevice sides can detach in different order.  Let's just be safe.
+ */
+struct ocfs2_live_connection {
+	struct list_head		oc_list;
+	struct ocfs2_cluster_connection	*oc_conn;
+};
+
+struct ocfs2_control_private {
+	struct list_head op_list;
+	int op_state;
+	int op_this_node;
+	struct ocfs2_protocol_version op_proto;
+};
+
+/* SETN<space><8-char-hex-nodenum><newline> */
+struct ocfs2_control_message_setn {
+	char	tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+	char	space;
+	char	nodestr[OCFS2_CONTROL_MESSAGE_NODENUM_LEN];
+	char	newline;
+};
+
+/* SETV<space><2-char-hex-major><space><2-char-hex-minor><newline> */
+struct ocfs2_control_message_setv {
+	char	tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+	char	space1;
+	char	major[OCFS2_CONTROL_MESSAGE_VERNUM_LEN];
+	char	space2;
+	char	minor[OCFS2_CONTROL_MESSAGE_VERNUM_LEN];
+	char	newline;
+};
+
+/* DOWN<space><32-char-cap-hex-uuid><space><8-char-hex-nodenum><newline> */
+struct ocfs2_control_message_down {
+	char	tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+	char	space1;
+	char	uuid[OCFS2_TEXT_UUID_LEN];
+	char	space2;
+	char	nodestr[OCFS2_CONTROL_MESSAGE_NODENUM_LEN];
+	char	newline;
+};
+
+union ocfs2_control_message {
+	char					tag[OCFS2_CONTROL_MESSAGE_OP_LEN];
+	struct ocfs2_control_message_setn	u_setn;
+	struct ocfs2_control_message_setv	u_setv;
+	struct ocfs2_control_message_down	u_down;
+};
+
+static struct ocfs2_stack_plugin user_stack;
+
+static atomic_t ocfs2_control_opened;
+static int ocfs2_control_this_node = -1;
+static struct ocfs2_protocol_version running_proto;
+
+static LIST_HEAD(ocfs2_live_connection_list);
+static LIST_HEAD(ocfs2_control_private_list);
+static DEFINE_MUTEX(ocfs2_control_lock);
+
+static inline void ocfs2_control_set_handshake_state(struct file *file,
+						     int state)
+{
+	struct ocfs2_control_private *p = file->private_data;
+	p->op_state = state;
+}
+
+static inline int ocfs2_control_get_handshake_state(struct file *file)
+{
+	struct ocfs2_control_private *p = file->private_data;
+	return p->op_state;
+}
+
+static struct ocfs2_live_connection *ocfs2_connection_find(const char *name)
+{
+	size_t len = strlen(name);
+	struct ocfs2_live_connection *c;
+
+	BUG_ON(!mutex_is_locked(&ocfs2_control_lock));
+
+	list_for_each_entry(c, &ocfs2_live_connection_list, oc_list) {
+		if ((c->oc_conn->cc_namelen == len) &&
+		    !strncmp(c->oc_conn->cc_name, name, len))
+			return c;
+	}
+
+	return c;
+}
+
+/*
+ * ocfs2_live_connection structures are created underneath the ocfs2
+ * mount path.  Since the VFS prevents multiple calls to
+ * fill_super(), we can't get dupes here.
+ */
+static int ocfs2_live_connection_new(struct ocfs2_cluster_connection *conn,
+				     struct ocfs2_live_connection **c_ret)
+{
+	int rc = 0;
+	struct ocfs2_live_connection *c;
+
+	c = kzalloc(sizeof(struct ocfs2_live_connection), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	mutex_lock(&ocfs2_control_lock);
+	c->oc_conn = conn;
+
+	if (atomic_read(&ocfs2_control_opened))
+		list_add(&c->oc_list, &ocfs2_live_connection_list);
+	else {
+		printk(KERN_ERR
+		       "ocfs2: Userspace control daemon is not present\n");
+		rc = -ESRCH;
+	}
+
+	mutex_unlock(&ocfs2_control_lock);
+
+	if (!rc)
+		*c_ret = c;
+	else
+		kfree(c);
+
+	return rc;
+}
+
+/*
+ * This function disconnects the cluster connection from ocfs2_control.
+ * Afterwards, userspace can't affect the cluster connection.
+ */
+static void ocfs2_live_connection_drop(struct ocfs2_live_connection *c)
+{
+	mutex_lock(&ocfs2_control_lock);
+	list_del_init(&c->oc_list);
+	c->oc_conn = NULL;
+	mutex_unlock(&ocfs2_control_lock);
+
+	kfree(c);
+}
+
+static int ocfs2_control_cfu(void *target, size_t target_len,
+			     const char __user *buf, size_t count)
+{
+	/* The T01 expects write(2) calls to have exactly one command */
+	if ((count != target_len) ||
+	    (count > sizeof(union ocfs2_control_message)))
+		return -EINVAL;
+
+	if (copy_from_user(target, buf, target_len))
+		return -EFAULT;
+
+	return 0;
+}
+
+static ssize_t ocfs2_control_validate_protocol(struct file *file,
+					       const char __user *buf,
+					       size_t count)
+{
+	ssize_t ret;
+	char kbuf[OCFS2_CONTROL_PROTO_LEN];
+
+	ret = ocfs2_control_cfu(kbuf, OCFS2_CONTROL_PROTO_LEN,
+				buf, count);
+	if (ret)
+		return ret;
+
+	if (strncmp(kbuf, OCFS2_CONTROL_PROTO, OCFS2_CONTROL_PROTO_LEN))
+		return -EINVAL;
+
+	ocfs2_control_set_handshake_state(file,
+					  OCFS2_CONTROL_HANDSHAKE_PROTOCOL);
+
+	return count;
+}
+
+static void ocfs2_control_send_down(const char *uuid,
+				    int nodenum)
+{
+	struct ocfs2_live_connection *c;
+
+	mutex_lock(&ocfs2_control_lock);
+
+	c = ocfs2_connection_find(uuid);
+	if (c) {
+		BUG_ON(c->oc_conn == NULL);
+		c->oc_conn->cc_recovery_handler(nodenum,
+						c->oc_conn->cc_recovery_data);
+	}
+
+	mutex_unlock(&ocfs2_control_lock);
+}
+
+/*
+ * Called whenever configuration elements are sent to /dev/ocfs2_control.
+ * If all configuration elements are present, try to set the global
+ * values.  If there is a problem, return an error.  Skip any missing
+ * elements, and only bump ocfs2_control_opened when we have all elements
+ * and are successful.
+ */
+static int ocfs2_control_install_private(struct file *file)
+{
+	int rc = 0;
+	int set_p = 1;
+	struct ocfs2_control_private *p = file->private_data;
+
+	BUG_ON(p->op_state != OCFS2_CONTROL_HANDSHAKE_PROTOCOL);
+
+	mutex_lock(&ocfs2_control_lock);
+
+	if (p->op_this_node < 0) {
+		set_p = 0;
+	} else if ((ocfs2_control_this_node >= 0) &&
+		   (ocfs2_control_this_node != p->op_this_node)) {
+		rc = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!p->op_proto.pv_major) {
+		set_p = 0;
+	} else if (!list_empty(&ocfs2_live_connection_list) &&
+		   ((running_proto.pv_major != p->op_proto.pv_major) ||
+		    (running_proto.pv_minor != p->op_proto.pv_minor))) {
+		rc = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (set_p) {
+		ocfs2_control_this_node = p->op_this_node;
+		running_proto.pv_major = p->op_proto.pv_major;
+		running_proto.pv_minor = p->op_proto.pv_minor;
+	}
+
+out_unlock:
+	mutex_unlock(&ocfs2_control_lock);
+
+	if (!rc && set_p) {
+		/* We set the global values successfully */
+		atomic_inc(&ocfs2_control_opened);
+		ocfs2_control_set_handshake_state(file,
+					OCFS2_CONTROL_HANDSHAKE_VALID);
+	}
+
+	return rc;
+}
+
+static int ocfs2_control_get_this_node(void)
+{
+	int rc;
+
+	mutex_lock(&ocfs2_control_lock);
+	if (ocfs2_control_this_node < 0)
+		rc = -EINVAL;
+	else
+		rc = ocfs2_control_this_node;
+	mutex_unlock(&ocfs2_control_lock);
+
+	return rc;
+}
+
+static int ocfs2_control_do_setnode_msg(struct file *file,
+					struct ocfs2_control_message_setn *msg)
+{
+	long nodenum;
+	char *ptr = NULL;
+	struct ocfs2_control_private *p = file->private_data;
+
+	if (ocfs2_control_get_handshake_state(file) !=
+	    OCFS2_CONTROL_HANDSHAKE_PROTOCOL)
+		return -EINVAL;
+
+	if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_SETNODE_OP,
+		    OCFS2_CONTROL_MESSAGE_OP_LEN))
+		return -EINVAL;
+
+	if ((msg->space != ' ') || (msg->newline != '\n'))
+		return -EINVAL;
+	msg->space = msg->newline = '\0';
+
+	nodenum = simple_strtol(msg->nodestr, &ptr, 16);
+	if (!ptr || *ptr)
+		return -EINVAL;
+
+	if ((nodenum == LONG_MIN) || (nodenum == LONG_MAX) ||
+	    (nodenum > INT_MAX) || (nodenum < 0))
+		return -ERANGE;
+	p->op_this_node = nodenum;
+
+	return ocfs2_control_install_private(file);
+}
+
+static int ocfs2_control_do_setversion_msg(struct file *file,
+					   struct ocfs2_control_message_setv *msg)
+ {
+	long major, minor;
+	char *ptr = NULL;
+	struct ocfs2_control_private *p = file->private_data;
+	struct ocfs2_protocol_version *max =
+		&user_stack.sp_proto->lp_max_version;
+
+	if (ocfs2_control_get_handshake_state(file) !=
+	    OCFS2_CONTROL_HANDSHAKE_PROTOCOL)
+		return -EINVAL;
+
+	if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_SETVERSION_OP,
+		    OCFS2_CONTROL_MESSAGE_OP_LEN))
+		return -EINVAL;
+
+	if ((msg->space1 != ' ') || (msg->space2 != ' ') ||
+	    (msg->newline != '\n'))
+		return -EINVAL;
+	msg->space1 = msg->space2 = msg->newline = '\0';
+
+	major = simple_strtol(msg->major, &ptr, 16);
+	if (!ptr || *ptr)
+		return -EINVAL;
+	minor = simple_strtol(msg->minor, &ptr, 16);
+	if (!ptr || *ptr)
+		return -EINVAL;
+
+	/*
+	 * The major must be between 1 and 255, inclusive.  The minor
+	 * must be between 0 and 255, inclusive.  The version passed in
+	 * must be within the maximum version supported by the filesystem.
+	 */
+	if ((major == LONG_MIN) || (major == LONG_MAX) ||
+	    (major > (u8)-1) || (major < 1))
+		return -ERANGE;
+	if ((minor == LONG_MIN) || (minor == LONG_MAX) ||
+	    (minor > (u8)-1) || (minor < 0))
+		return -ERANGE;
+	if ((major != max->pv_major) ||
+	    (minor > max->pv_minor))
+		return -EINVAL;
+
+	p->op_proto.pv_major = major;
+	p->op_proto.pv_minor = minor;
+
+	return ocfs2_control_install_private(file);
+}
+
+static int ocfs2_control_do_down_msg(struct file *file,
+				     struct ocfs2_control_message_down *msg)
+{
+	long nodenum;
+	char *p = NULL;
+
+	if (ocfs2_control_get_handshake_state(file) !=
+	    OCFS2_CONTROL_HANDSHAKE_VALID)
+		return -EINVAL;
+
+	if (strncmp(msg->tag, OCFS2_CONTROL_MESSAGE_DOWN_OP,
+		    OCFS2_CONTROL_MESSAGE_OP_LEN))
+		return -EINVAL;
+
+	if ((msg->space1 != ' ') || (msg->space2 != ' ') ||
+	    (msg->newline != '\n'))
+		return -EINVAL;
+	msg->space1 = msg->space2 = msg->newline = '\0';
+
+	nodenum = simple_strtol(msg->nodestr, &p, 16);
+	if (!p || *p)
+		return -EINVAL;
+
+	if ((nodenum == LONG_MIN) || (nodenum == LONG_MAX) ||
+	    (nodenum > INT_MAX) || (nodenum < 0))
+		return -ERANGE;
+
+	ocfs2_control_send_down(msg->uuid, nodenum);
+
+	return 0;
+}
+
+static ssize_t ocfs2_control_message(struct file *file,
+				     const char __user *buf,
+				     size_t count)
+{
+	ssize_t ret;
+	union ocfs2_control_message msg;
+
+	/* Try to catch padding issues */
+	WARN_ON(offsetof(struct ocfs2_control_message_down, uuid) !=
+		(sizeof(msg.u_down.tag) + sizeof(msg.u_down.space1)));
+
+	memset(&msg, 0, sizeof(union ocfs2_control_message));
+	ret = ocfs2_control_cfu(&msg, count, buf, count);
+	if (ret)
+		goto out;
+
+	if ((count == OCFS2_CONTROL_MESSAGE_SETNODE_TOTAL_LEN) &&
+	    !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_SETNODE_OP,
+		     OCFS2_CONTROL_MESSAGE_OP_LEN))
+		ret = ocfs2_control_do_setnode_msg(file, &msg.u_setn);
+	else if ((count == OCFS2_CONTROL_MESSAGE_SETVERSION_TOTAL_LEN) &&
+		 !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_SETVERSION_OP,
+			  OCFS2_CONTROL_MESSAGE_OP_LEN))
+		ret = ocfs2_control_do_setversion_msg(file, &msg.u_setv);
+	else if ((count == OCFS2_CONTROL_MESSAGE_DOWN_TOTAL_LEN) &&
+		 !strncmp(msg.tag, OCFS2_CONTROL_MESSAGE_DOWN_OP,
+			  OCFS2_CONTROL_MESSAGE_OP_LEN))
+		ret = ocfs2_control_do_down_msg(file, &msg.u_down);
+	else
+		ret = -EINVAL;
+
+out:
+	return ret ? ret : count;
+}
+
+static ssize_t ocfs2_control_write(struct file *file,
+				   const char __user *buf,
+				   size_t count,
+				   loff_t *ppos)
+{
+	ssize_t ret;
+
+	switch (ocfs2_control_get_handshake_state(file)) {
+		case OCFS2_CONTROL_HANDSHAKE_INVALID:
+			ret = -EINVAL;
+			break;
+
+		case OCFS2_CONTROL_HANDSHAKE_READ:
+			ret = ocfs2_control_validate_protocol(file, buf,
+							      count);
+			break;
+
+		case OCFS2_CONTROL_HANDSHAKE_PROTOCOL:
+		case OCFS2_CONTROL_HANDSHAKE_VALID:
+			ret = ocfs2_control_message(file, buf, count);
+			break;
+
+		default:
+			BUG();
+			ret = -EIO;
+			break;
+	}
+
+	return ret;
+}
+
+/*
+ * This is a naive version.  If we ever have a new protocol, we'll expand
+ * it.  Probably using seq_file.
+ */
+static ssize_t ocfs2_control_read(struct file *file,
+				  char __user *buf,
+				  size_t count,
+				  loff_t *ppos)
+{
+	char *proto_string = OCFS2_CONTROL_PROTO;
+	size_t to_write = 0;
+
+	if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
+		return 0;
+
+	to_write = OCFS2_CONTROL_PROTO_LEN - *ppos;
+	if (to_write > count)
+		to_write = count;
+	if (copy_to_user(buf, proto_string + *ppos, to_write))
+		return -EFAULT;
+
+	*ppos += to_write;
+
+	/* Have we read the whole protocol list? */
+	if (*ppos >= OCFS2_CONTROL_PROTO_LEN)
+		ocfs2_control_set_handshake_state(file,
+						  OCFS2_CONTROL_HANDSHAKE_READ);
+
+	return to_write;
+}
+
+static int ocfs2_control_release(struct inode *inode, struct file *file)
+{
+	struct ocfs2_control_private *p = file->private_data;
+
+	mutex_lock(&ocfs2_control_lock);
+
+	if (ocfs2_control_get_handshake_state(file) !=
+	    OCFS2_CONTROL_HANDSHAKE_VALID)
+		goto out;
+
+	if (atomic_dec_and_test(&ocfs2_control_opened)) {
+		if (!list_empty(&ocfs2_live_connection_list)) {
+			/* XXX: Do bad things! */
+			printk(KERN_ERR
+			       "ocfs2: Unexpected release of ocfs2_control!\n"
+			       "       Loss of cluster connection requires "
+			       "an emergency restart!\n");
+			emergency_restart();
+		}
+		/*
+		 * Last valid close clears the node number and resets
+		 * the locking protocol version
+		 */
+		ocfs2_control_this_node = -1;
+		running_proto.pv_major = 0;
+		running_proto.pv_major = 0;
+	}
+
+out:
+	list_del_init(&p->op_list);
+	file->private_data = NULL;
+
+	mutex_unlock(&ocfs2_control_lock);
+
+	kfree(p);
+
+	return 0;
+}
+
+static int ocfs2_control_open(struct inode *inode, struct file *file)
+{
+	struct ocfs2_control_private *p;
+
+	p = kzalloc(sizeof(struct ocfs2_control_private), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+	p->op_this_node = -1;
+
+	mutex_lock(&ocfs2_control_lock);
+	file->private_data = p;
+	list_add(&p->op_list, &ocfs2_control_private_list);
+	mutex_unlock(&ocfs2_control_lock);
+
+	return 0;
+}
+
+static const struct file_operations ocfs2_control_fops = {
+	.open    = ocfs2_control_open,
+	.release = ocfs2_control_release,
+	.read    = ocfs2_control_read,
+	.write   = ocfs2_control_write,
+	.owner   = THIS_MODULE,
+};
+
+struct miscdevice ocfs2_control_device = {
+	.minor		= MISC_DYNAMIC_MINOR,
+	.name		= "ocfs2_control",
+	.fops		= &ocfs2_control_fops,
+};
+
+static int ocfs2_control_init(void)
+{
+	int rc;
+
+	atomic_set(&ocfs2_control_opened, 0);
+
+	rc = misc_register(&ocfs2_control_device);
+	if (rc)
+		printk(KERN_ERR
+		       "ocfs2: Unable to register ocfs2_control device "
+		       "(errno %d)\n",
+		       -rc);
+
+	return rc;
+}
+
+static void ocfs2_control_exit(void)
+{
+	int rc;
+
+	rc = misc_deregister(&ocfs2_control_device);
+	if (rc)
+		printk(KERN_ERR
+		       "ocfs2: Unable to deregister ocfs2_control device "
+		       "(errno %d)\n",
+		       -rc);
+}
+
+static struct dlm_lksb *fsdlm_astarg_to_lksb(void *astarg)
+{
+	struct ocfs2_lock_res *res = astarg;
+	return &res->l_lksb.lksb_fsdlm;
+}
+
+static void fsdlm_lock_ast_wrapper(void *astarg)
+{
+	struct dlm_lksb *lksb = fsdlm_astarg_to_lksb(astarg);
+	int status = lksb->sb_status;
+
+	BUG_ON(user_stack.sp_proto == NULL);
+
+	/*
+	 * For now we're punting on the issue of other non-standard errors
+	 * where we can't tell if the unlock_ast or lock_ast should be called.
+	 * The main "other error" that's possible is EINVAL which means the
+	 * function was called with invalid args, which shouldn't be possible
+	 * since the caller here is under our control.  Other non-standard
+	 * errors probably fall into the same category, or otherwise are fatal
+	 * which means we can't carry on anyway.
+	 */
+
+	if (status == -DLM_EUNLOCK || status == -DLM_ECANCEL)
+		user_stack.sp_proto->lp_unlock_ast(astarg, 0);
+	else
+		user_stack.sp_proto->lp_lock_ast(astarg);
+}
+
+static void fsdlm_blocking_ast_wrapper(void *astarg, int level)
+{
+	BUG_ON(user_stack.sp_proto == NULL);
+
+	user_stack.sp_proto->lp_blocking_ast(astarg, level);
+}
+
+static int user_dlm_lock(struct ocfs2_cluster_connection *conn,
+			 int mode,
+			 union ocfs2_dlm_lksb *lksb,
+			 u32 flags,
+			 void *name,
+			 unsigned int namelen,
+			 void *astarg)
+{
+	int ret;
+
+	if (!lksb->lksb_fsdlm.sb_lvbptr)
+		lksb->lksb_fsdlm.sb_lvbptr = (char *)lksb +
+					     sizeof(struct dlm_lksb);
+
+	ret = dlm_lock(conn->cc_lockspace, mode, &lksb->lksb_fsdlm,
+		       flags|DLM_LKF_NODLCKWT, name, namelen, 0,
+		       fsdlm_lock_ast_wrapper, astarg,
+		       fsdlm_blocking_ast_wrapper);
+	return ret;
+}
+
+static int user_dlm_unlock(struct ocfs2_cluster_connection *conn,
+			   union ocfs2_dlm_lksb *lksb,
+			   u32 flags,
+			   void *astarg)
+{
+	int ret;
+
+	ret = dlm_unlock(conn->cc_lockspace, lksb->lksb_fsdlm.sb_lkid,
+			 flags, &lksb->lksb_fsdlm, astarg);
+	return ret;
+}
+
+static int user_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+	return lksb->lksb_fsdlm.sb_status;
+}
+
+static void *user_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+	return (void *)(lksb->lksb_fsdlm.sb_lvbptr);
+}
+
+static void user_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+}
+
+/*
+ * Compare a requested locking protocol version against the current one.
+ *
+ * If the major numbers are different, they are incompatible.
+ * If the current minor is greater than the request, they are incompatible.
+ * If the current minor is less than or equal to the request, they are
+ * compatible, and the requester should run at the current minor version.
+ */
+static int fs_protocol_compare(struct ocfs2_protocol_version *existing,
+			       struct ocfs2_protocol_version *request)
+{
+	if (existing->pv_major != request->pv_major)
+		return 1;
+
+	if (existing->pv_minor > request->pv_minor)
+		return 1;
+
+	if (existing->pv_minor < request->pv_minor)
+		request->pv_minor = existing->pv_minor;
+
+	return 0;
+}
+
+static int user_cluster_connect(struct ocfs2_cluster_connection *conn)
+{
+	dlm_lockspace_t *fsdlm;
+	struct ocfs2_live_connection *control;
+	int rc = 0;
+
+	BUG_ON(conn == NULL);
+
+	rc = ocfs2_live_connection_new(conn, &control);
+	if (rc)
+		goto out;
+
+	/*
+	 * running_proto must have been set before we allowed any mounts
+	 * to proceed.
+	 */
+	if (fs_protocol_compare(&running_proto, &conn->cc_version)) {
+		printk(KERN_ERR
+		       "Unable to mount with fs locking protocol version "
+		       "%u.%u because the userspace control daemon has "
+		       "negotiated %u.%u\n",
+		       conn->cc_version.pv_major, conn->cc_version.pv_minor,
+		       running_proto.pv_major, running_proto.pv_minor);
+		rc = -EPROTO;
+		ocfs2_live_connection_drop(control);
+		goto out;
+	}
+
+	rc = dlm_new_lockspace(conn->cc_name, strlen(conn->cc_name),
+			       &fsdlm, DLM_LSFL_FS, DLM_LVB_LEN);
+	if (rc) {
+		ocfs2_live_connection_drop(control);
+		goto out;
+	}
+
+	conn->cc_private = control;
+	conn->cc_lockspace = fsdlm;
+out:
+	return rc;
+}
+
+static int user_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+				   int hangup_pending)
+{
+	dlm_release_lockspace(conn->cc_lockspace, 2);
+	conn->cc_lockspace = NULL;
+	ocfs2_live_connection_drop(conn->cc_private);
+	conn->cc_private = NULL;
+	return 0;
+}
+
+static int user_cluster_this_node(unsigned int *this_node)
+{
+	int rc;
+
+	rc = ocfs2_control_get_this_node();
+	if (rc < 0)
+		return rc;
+
+	*this_node = rc;
+	return 0;
+}
+
+static struct ocfs2_stack_operations user_stack_ops = {
+	.connect	= user_cluster_connect,
+	.disconnect	= user_cluster_disconnect,
+	.this_node	= user_cluster_this_node,
+	.dlm_lock	= user_dlm_lock,
+	.dlm_unlock	= user_dlm_unlock,
+	.lock_status	= user_dlm_lock_status,
+	.lock_lvb	= user_dlm_lvb,
+	.dump_lksb	= user_dlm_dump_lksb,
+};
+
+static struct ocfs2_stack_plugin user_stack = {
+	.sp_name	= "user",
+	.sp_ops		= &user_stack_ops,
+	.sp_owner	= THIS_MODULE,
+};
+
+
+static int __init user_stack_init(void)
+{
+	int rc;
+
+	rc = ocfs2_control_init();
+	if (!rc) {
+		rc = ocfs2_stack_glue_register(&user_stack);
+		if (rc)
+			ocfs2_control_exit();
+	}
+
+	return rc;
+}
+
+static void __exit user_stack_exit(void)
+{
+	ocfs2_stack_glue_unregister(&user_stack);
+	ocfs2_control_exit();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 driver for userspace cluster stacks");
+MODULE_LICENSE("GPL");
+module_init(user_stack_init);
+module_exit(user_stack_exit);
diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
new file mode 100644
index 00000000000..119f60cea9c
--- /dev/null
+++ b/fs/ocfs2/stackglue.c
@@ -0,0 +1,568 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stackglue.c
+ *
+ * Code which implements an OCFS2 specific interface to underlying
+ * cluster stacks.
+ *
+ * Copyright (C) 2007 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, version 2.
+ *
+ * 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.
+ */
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kmod.h>
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+
+#include "ocfs2_fs.h"
+
+#include "stackglue.h"
+
+#define OCFS2_STACK_PLUGIN_O2CB		"o2cb"
+#define OCFS2_STACK_PLUGIN_USER		"user"
+
+static struct ocfs2_locking_protocol *lproto;
+static DEFINE_SPINLOCK(ocfs2_stack_lock);
+static LIST_HEAD(ocfs2_stack_list);
+static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
+
+/*
+ * The stack currently in use.  If not null, active_stack->sp_count > 0,
+ * the module is pinned, and the locking protocol cannot be changed.
+ */
+static struct ocfs2_stack_plugin *active_stack;
+
+static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
+{
+	struct ocfs2_stack_plugin *p;
+
+	assert_spin_locked(&ocfs2_stack_lock);
+
+	list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+		if (!strcmp(p->sp_name, name))
+			return p;
+	}
+
+	return NULL;
+}
+
+static int ocfs2_stack_driver_request(const char *stack_name,
+				      const char *plugin_name)
+{
+	int rc;
+	struct ocfs2_stack_plugin *p;
+
+	spin_lock(&ocfs2_stack_lock);
+
+	/*
+	 * If the stack passed by the filesystem isn't the selected one,
+	 * we can't continue.
+	 */
+	if (strcmp(stack_name, cluster_stack_name)) {
+		rc = -EBUSY;
+		goto out;
+	}
+
+	if (active_stack) {
+		/*
+		 * If the active stack isn't the one we want, it cannot
+		 * be selected right now.
+		 */
+		if (!strcmp(active_stack->sp_name, plugin_name))
+			rc = 0;
+		else
+			rc = -EBUSY;
+		goto out;
+	}
+
+	p = ocfs2_stack_lookup(plugin_name);
+	if (!p || !try_module_get(p->sp_owner)) {
+		rc = -ENOENT;
+		goto out;
+	}
+
+	/* Ok, the stack is pinned */
+	p->sp_count++;
+	active_stack = p;
+
+	rc = 0;
+
+out:
+	spin_unlock(&ocfs2_stack_lock);
+	return rc;
+}
+
+/*
+ * This function looks up the appropriate stack and makes it active.  If
+ * there is no stack, it tries to load it.  It will fail if the stack still
+ * cannot be found.  It will also fail if a different stack is in use.
+ */
+static int ocfs2_stack_driver_get(const char *stack_name)
+{
+	int rc;
+	char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
+
+	/*
+	 * Classic stack does not pass in a stack name.  This is
+	 * compatible with older tools as well.
+	 */
+	if (!stack_name || !*stack_name)
+		stack_name = OCFS2_STACK_PLUGIN_O2CB;
+
+	if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
+		printk(KERN_ERR
+		       "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
+		       stack_name);
+		return -EINVAL;
+	}
+
+	/* Anything that isn't the classic stack is a user stack */
+	if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
+		plugin_name = OCFS2_STACK_PLUGIN_USER;
+
+	rc = ocfs2_stack_driver_request(stack_name, plugin_name);
+	if (rc == -ENOENT) {
+		request_module("ocfs2_stack_%s", plugin_name);
+		rc = ocfs2_stack_driver_request(stack_name, plugin_name);
+	}
+
+	if (rc == -ENOENT) {
+		printk(KERN_ERR
+		       "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
+		       plugin_name);
+	} else if (rc == -EBUSY) {
+		printk(KERN_ERR
+		       "ocfs2: A different cluster stack is in use\n");
+	}
+
+	return rc;
+}
+
+static void ocfs2_stack_driver_put(void)
+{
+	spin_lock(&ocfs2_stack_lock);
+	BUG_ON(active_stack == NULL);
+	BUG_ON(active_stack->sp_count == 0);
+
+	active_stack->sp_count--;
+	if (!active_stack->sp_count) {
+		module_put(active_stack->sp_owner);
+		active_stack = NULL;
+	}
+	spin_unlock(&ocfs2_stack_lock);
+}
+
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
+{
+	int rc;
+
+	spin_lock(&ocfs2_stack_lock);
+	if (!ocfs2_stack_lookup(plugin->sp_name)) {
+		plugin->sp_count = 0;
+		plugin->sp_proto = lproto;
+		list_add(&plugin->sp_list, &ocfs2_stack_list);
+		printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
+		       plugin->sp_name);
+		rc = 0;
+	} else {
+		printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
+		       plugin->sp_name);
+		rc = -EEXIST;
+	}
+	spin_unlock(&ocfs2_stack_lock);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
+
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
+{
+	struct ocfs2_stack_plugin *p;
+
+	spin_lock(&ocfs2_stack_lock);
+	p = ocfs2_stack_lookup(plugin->sp_name);
+	if (p) {
+		BUG_ON(p != plugin);
+		BUG_ON(plugin == active_stack);
+		BUG_ON(plugin->sp_count != 0);
+		list_del_init(&plugin->sp_list);
+		printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
+		       plugin->sp_name);
+	} else {
+		printk(KERN_ERR "Stack \"%s\" is not registered\n",
+		       plugin->sp_name);
+	}
+	spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
+{
+	struct ocfs2_stack_plugin *p;
+
+	BUG_ON(proto == NULL);
+
+	spin_lock(&ocfs2_stack_lock);
+	BUG_ON(active_stack != NULL);
+
+	lproto = proto;
+	list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+		p->sp_proto = lproto;
+	}
+
+	spin_unlock(&ocfs2_stack_lock);
+}
+EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
+
+
+/*
+ * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
+ * "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
+ * underlying stack plugins need to pilfer the lksb off of the lock_res.
+ * If some other structure needs to be passed as an astarg, the plugins
+ * will need to be given a different avenue to the lksb.
+ */
+int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
+		   int mode,
+		   union ocfs2_dlm_lksb *lksb,
+		   u32 flags,
+		   void *name,
+		   unsigned int namelen,
+		   struct ocfs2_lock_res *astarg)
+{
+	BUG_ON(lproto == NULL);
+
+	return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
+					      name, namelen, astarg);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
+
+int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
+		     union ocfs2_dlm_lksb *lksb,
+		     u32 flags,
+		     struct ocfs2_lock_res *astarg)
+{
+	BUG_ON(lproto == NULL);
+
+	return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
+
+int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
+{
+	return active_stack->sp_ops->lock_status(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
+
+/*
+ * Why don't we cast to ocfs2_meta_lvb?  The "clean" answer is that we
+ * don't cast at the glue level.  The real answer is that the header
+ * ordering is nigh impossible.
+ */
+void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
+{
+	return active_stack->sp_ops->lock_lvb(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
+
+void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
+{
+	active_stack->sp_ops->dump_lksb(lksb);
+}
+EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
+
+int ocfs2_cluster_connect(const char *stack_name,
+			  const char *group,
+			  int grouplen,
+			  void (*recovery_handler)(int node_num,
+						   void *recovery_data),
+			  void *recovery_data,
+			  struct ocfs2_cluster_connection **conn)
+{
+	int rc = 0;
+	struct ocfs2_cluster_connection *new_conn;
+
+	BUG_ON(group == NULL);
+	BUG_ON(conn == NULL);
+	BUG_ON(recovery_handler == NULL);
+
+	if (grouplen > GROUP_NAME_MAX) {
+		rc = -EINVAL;
+		goto out;
+	}
+
+	new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
+			   GFP_KERNEL);
+	if (!new_conn) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	memcpy(new_conn->cc_name, group, grouplen);
+	new_conn->cc_namelen = grouplen;
+	new_conn->cc_recovery_handler = recovery_handler;
+	new_conn->cc_recovery_data = recovery_data;
+
+	/* Start the new connection at our maximum compatibility level */
+	new_conn->cc_version = lproto->lp_max_version;
+
+	/* This will pin the stack driver if successful */
+	rc = ocfs2_stack_driver_get(stack_name);
+	if (rc)
+		goto out_free;
+
+	rc = active_stack->sp_ops->connect(new_conn);
+	if (rc) {
+		ocfs2_stack_driver_put();
+		goto out_free;
+	}
+
+	*conn = new_conn;
+
+out_free:
+	if (rc)
+		kfree(new_conn);
+
+out:
+	return rc;
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
+
+/* If hangup_pending is 0, the stack driver will be dropped */
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+			     int hangup_pending)
+{
+	int ret;
+
+	BUG_ON(conn == NULL);
+
+	ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
+
+	/* XXX Should we free it anyway? */
+	if (!ret) {
+		kfree(conn);
+		if (!hangup_pending)
+			ocfs2_stack_driver_put();
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
+
+void ocfs2_cluster_hangup(const char *group, int grouplen)
+{
+	BUG_ON(group == NULL);
+	BUG_ON(group[grouplen] != '\0');
+
+	if (active_stack->sp_ops->hangup)
+		active_stack->sp_ops->hangup(group, grouplen);
+
+	/* cluster_disconnect() was called with hangup_pending==1 */
+	ocfs2_stack_driver_put();
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
+
+int ocfs2_cluster_this_node(unsigned int *node)
+{
+	return active_stack->sp_ops->this_node(node);
+}
+EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
+
+
+/*
+ * Sysfs bits
+ */
+
+static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
+					       struct kobj_attribute *attr,
+					       char *buf)
+{
+	ssize_t ret = 0;
+
+	spin_lock(&ocfs2_stack_lock);
+	if (lproto)
+		ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
+			       lproto->lp_max_version.pv_major,
+			       lproto->lp_max_version.pv_minor);
+	spin_unlock(&ocfs2_stack_lock);
+
+	return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_max_locking_protocol =
+	__ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
+	       ocfs2_max_locking_protocol_show, NULL);
+
+static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
+						 struct kobj_attribute *attr,
+						 char *buf)
+{
+	ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
+	struct ocfs2_stack_plugin *p;
+
+	spin_lock(&ocfs2_stack_lock);
+	list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+		ret = snprintf(buf, remain, "%s\n",
+			       p->sp_name);
+		if (ret < 0) {
+			total = ret;
+			break;
+		}
+		if (ret == remain) {
+			/* snprintf() didn't fit */
+			total = -E2BIG;
+			break;
+		}
+		total += ret;
+		remain -= ret;
+	}
+	spin_unlock(&ocfs2_stack_lock);
+
+	return total;
+}
+
+static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
+	__ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
+	       ocfs2_loaded_cluster_plugins_show, NULL);
+
+static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
+						struct kobj_attribute *attr,
+						char *buf)
+{
+	ssize_t ret = 0;
+
+	spin_lock(&ocfs2_stack_lock);
+	if (active_stack) {
+		ret = snprintf(buf, PAGE_SIZE, "%s\n",
+			       active_stack->sp_name);
+		if (ret == PAGE_SIZE)
+			ret = -E2BIG;
+	}
+	spin_unlock(&ocfs2_stack_lock);
+
+	return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
+	__ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
+	       ocfs2_active_cluster_plugin_show, NULL);
+
+static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					char *buf)
+{
+	ssize_t ret;
+	spin_lock(&ocfs2_stack_lock);
+	ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
+	spin_unlock(&ocfs2_stack_lock);
+
+	return ret;
+}
+
+static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 const char *buf, size_t count)
+{
+	size_t len = count;
+	ssize_t ret;
+
+	if (len == 0)
+		return len;
+
+	if (buf[len - 1] == '\n')
+		len--;
+
+	if ((len != OCFS2_STACK_LABEL_LEN) ||
+	    (strnlen(buf, len) != len))
+		return -EINVAL;
+
+	spin_lock(&ocfs2_stack_lock);
+	if (active_stack) {
+		if (!strncmp(buf, cluster_stack_name, len))
+			ret = count;
+		else
+			ret = -EBUSY;
+	} else {
+		memcpy(cluster_stack_name, buf, len);
+		ret = count;
+	}
+	spin_unlock(&ocfs2_stack_lock);
+
+	return ret;
+}
+
+
+static struct kobj_attribute ocfs2_attr_cluster_stack =
+	__ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
+	       ocfs2_cluster_stack_show,
+	       ocfs2_cluster_stack_store);
+
+static struct attribute *ocfs2_attrs[] = {
+	&ocfs2_attr_max_locking_protocol.attr,
+	&ocfs2_attr_loaded_cluster_plugins.attr,
+	&ocfs2_attr_active_cluster_plugin.attr,
+	&ocfs2_attr_cluster_stack.attr,
+	NULL,
+};
+
+static struct attribute_group ocfs2_attr_group = {
+	.attrs = ocfs2_attrs,
+};
+
+static struct kset *ocfs2_kset;
+
+static void ocfs2_sysfs_exit(void)
+{
+	kset_unregister(ocfs2_kset);
+}
+
+static int ocfs2_sysfs_init(void)
+{
+	int ret;
+
+	ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
+	if (!ocfs2_kset)
+		return -ENOMEM;
+
+	ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
+	if (ret)
+		goto error;
+
+	return 0;
+
+error:
+	kset_unregister(ocfs2_kset);
+	return ret;
+}
+
+static int __init ocfs2_stack_glue_init(void)
+{
+	strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
+
+	return ocfs2_sysfs_init();
+}
+
+static void __exit ocfs2_stack_glue_exit(void)
+{
+	lproto = NULL;
+	ocfs2_sysfs_exit();
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
+MODULE_LICENSE("GPL");
+module_init(ocfs2_stack_glue_init);
+module_exit(ocfs2_stack_glue_exit);
diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h
new file mode 100644
index 00000000000..005e4f170e0
--- /dev/null
+++ b/fs/ocfs2/stackglue.h
@@ -0,0 +1,261 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * stackglue.h
+ *
+ * Glue to the underlying cluster stack.
+ *
+ * Copyright (C) 2007 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, version 2.
+ *
+ * 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.
+ */
+
+
+#ifndef STACKGLUE_H
+#define STACKGLUE_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/dlmconstants.h>
+
+#include "dlm/dlmapi.h"
+#include <linux/dlm.h>
+
+/*
+ * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
+ * some day, but right now we need it.  Let's fake it.  This value is larger
+ * than any flag in dlmconstants.h.
+ */
+#define DLM_LKF_LOCAL		0x00100000
+
+/*
+ * This shadows DLM_LOCKSPACE_LEN in fs/dlm/dlm_internal.h.  That probably
+ * wants to be in a public header.
+ */
+#define GROUP_NAME_MAX		64
+
+
+/*
+ * ocfs2_protocol_version changes when ocfs2 does something different in
+ * its inter-node behavior.  See dlmglue.c for more information.
+ */
+struct ocfs2_protocol_version {
+	u8 pv_major;
+	u8 pv_minor;
+};
+
+/*
+ * The ocfs2_locking_protocol defines the handlers called on ocfs2's behalf.
+ */
+struct ocfs2_locking_protocol {
+	struct ocfs2_protocol_version lp_max_version;
+	void (*lp_lock_ast)(void *astarg);
+	void (*lp_blocking_ast)(void *astarg, int level);
+	void (*lp_unlock_ast)(void *astarg, int error);
+};
+
+
+/*
+ * The dlm_lockstatus struct includes lvb space, but the dlm_lksb struct only
+ * has a pointer to separately allocated lvb space.  This struct exists only to
+ * include in the lksb union to make space for a combined dlm_lksb and lvb.
+ */
+struct fsdlm_lksb_plus_lvb {
+	struct dlm_lksb lksb;
+	char lvb[DLM_LVB_LEN];
+};
+
+/*
+ * A union of all lock status structures.  We define it here so that the
+ * size of the union is known.  Lock status structures are embedded in
+ * ocfs2 inodes.
+ */
+union ocfs2_dlm_lksb {
+	struct dlm_lockstatus lksb_o2dlm;
+	struct dlm_lksb lksb_fsdlm;
+	struct fsdlm_lksb_plus_lvb padding;
+};
+
+/*
+ * A cluster connection.  Mostly opaque to ocfs2, the connection holds
+ * state for the underlying stack.  ocfs2 does use cc_version to determine
+ * locking compatibility.
+ */
+struct ocfs2_cluster_connection {
+	char cc_name[GROUP_NAME_MAX];
+	int cc_namelen;
+	struct ocfs2_protocol_version cc_version;
+	void (*cc_recovery_handler)(int node_num, void *recovery_data);
+	void *cc_recovery_data;
+	void *cc_lockspace;
+	void *cc_private;
+};
+
+/*
+ * Each cluster stack implements the stack operations structure.  Not used
+ * in the ocfs2 code, the stackglue code translates generic cluster calls
+ * into stack operations.
+ */
+struct ocfs2_stack_operations {
+	/*
+	 * The fs code calls ocfs2_cluster_connect() to attach a new
+	 * filesystem to the cluster stack.  The ->connect() op is passed
+	 * an ocfs2_cluster_connection with the name and recovery field
+	 * filled in.
+	 *
+	 * The stack must set up any notification mechanisms and create
+	 * the filesystem lockspace in the DLM.  The lockspace should be
+	 * stored on cc_lockspace.  Any other information can be stored on
+	 * cc_private.
+	 *
+	 * ->connect() must not return until it is guaranteed that
+	 *
+	 *  - Node down notifications for the filesystem will be recieved
+	 *    and passed to conn->cc_recovery_handler().
+	 *  - Locking requests for the filesystem will be processed.
+	 */
+	int (*connect)(struct ocfs2_cluster_connection *conn);
+
+	/*
+	 * The fs code calls ocfs2_cluster_disconnect() when a filesystem
+	 * no longer needs cluster services.  All DLM locks have been
+	 * dropped, and recovery notification is being ignored by the
+	 * fs code.  The stack must disengage from the DLM and discontinue
+	 * recovery notification.
+	 *
+	 * Once ->disconnect() has returned, the connection structure will
+	 * be freed.  Thus, a stack must not return from ->disconnect()
+	 * until it will no longer reference the conn pointer.
+	 *
+	 * If hangup_pending is zero, ocfs2_cluster_disconnect() will also
+	 * be dropping the reference on the module.
+	 */
+	int (*disconnect)(struct ocfs2_cluster_connection *conn,
+			  int hangup_pending);
+
+	/*
+	 * ocfs2_cluster_hangup() exists for compatibility with older
+	 * ocfs2 tools.  Only the classic stack really needs it.  As such
+	 * ->hangup() is not required of all stacks.  See the comment by
+	 * ocfs2_cluster_hangup() for more details.
+	 *
+	 * Note that ocfs2_cluster_hangup() can only be called if
+	 * hangup_pending was passed to ocfs2_cluster_disconnect().
+	 */
+	void (*hangup)(const char *group, int grouplen);
+
+	/*
+	 * ->this_node() returns the cluster's unique identifier for the
+	 * local node.
+	 */
+	int (*this_node)(unsigned int *node);
+
+	/*
+	 * Call the underlying dlm lock function.  The ->dlm_lock()
+	 * callback should convert the flags and mode as appropriate.
+	 *
+	 * ast and bast functions are not part of the call because the
+	 * stack will likely want to wrap ast and bast calls before passing
+	 * them to stack->sp_proto.
+	 */
+	int (*dlm_lock)(struct ocfs2_cluster_connection *conn,
+			int mode,
+			union ocfs2_dlm_lksb *lksb,
+			u32 flags,
+			void *name,
+			unsigned int namelen,
+			void *astarg);
+
+	/*
+	 * Call the underlying dlm unlock function.  The ->dlm_unlock()
+	 * function should convert the flags as appropriate.
+	 *
+	 * The unlock ast is not passed, as the stack will want to wrap
+	 * it before calling stack->sp_proto->lp_unlock_ast().
+	 */
+	int (*dlm_unlock)(struct ocfs2_cluster_connection *conn,
+			  union ocfs2_dlm_lksb *lksb,
+			  u32 flags,
+			  void *astarg);
+
+	/*
+	 * Return the status of the current lock status block.  The fs
+	 * code should never dereference the union.  The ->lock_status()
+	 * callback pulls out the stack-specific lksb, converts the status
+	 * to a proper errno, and returns it.
+	 */
+	int (*lock_status)(union ocfs2_dlm_lksb *lksb);
+
+	/*
+	 * Pull the lvb pointer off of the stack-specific lksb.
+	 */
+	void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
+
+	/*
+	 * This is an optoinal debugging hook.  If provided, the
+	 * stack can dump debugging information about this lock.
+	 */
+	void (*dump_lksb)(union ocfs2_dlm_lksb *lksb);
+};
+
+/*
+ * Each stack plugin must describe itself by registering a
+ * ocfs2_stack_plugin structure.  This is only seen by stackglue and the
+ * stack driver.
+ */
+struct ocfs2_stack_plugin {
+	char *sp_name;
+	struct ocfs2_stack_operations *sp_ops;
+	struct module *sp_owner;
+
+	/* These are managed by the stackglue code. */
+	struct list_head sp_list;
+	unsigned int sp_count;
+	struct ocfs2_locking_protocol *sp_proto;
+};
+
+
+/* Used by the filesystem */
+int ocfs2_cluster_connect(const char *stack_name,
+			  const char *group,
+			  int grouplen,
+			  void (*recovery_handler)(int node_num,
+						   void *recovery_data),
+			  void *recovery_data,
+			  struct ocfs2_cluster_connection **conn);
+int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
+			     int hangup_pending);
+void ocfs2_cluster_hangup(const char *group, int grouplen);
+int ocfs2_cluster_this_node(unsigned int *node);
+
+struct ocfs2_lock_res;
+int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
+		   int mode,
+		   union ocfs2_dlm_lksb *lksb,
+		   u32 flags,
+		   void *name,
+		   unsigned int namelen,
+		   struct ocfs2_lock_res *astarg);
+int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
+		     union ocfs2_dlm_lksb *lksb,
+		     u32 flags,
+		     struct ocfs2_lock_res *astarg);
+
+int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
+void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
+void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
+
+void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);
+
+
+/* Used by stack plugins */
+int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin);
+void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin);
+#endif  /* STACKGLUE_H */
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 72c198a004d..d2d278fb981 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -46,6 +46,11 @@
 
 #include "buffer_head_io.h"
 
+#define NOT_ALLOC_NEW_GROUP		0
+#define ALLOC_NEW_GROUP			1
+
+#define OCFS2_MAX_INODES_TO_STEAL	1024
+
 static inline void ocfs2_debug_bg(struct ocfs2_group_desc *bg);
 static inline void ocfs2_debug_suballoc_inode(struct ocfs2_dinode *fe);
 static inline u16 ocfs2_find_victim_chain(struct ocfs2_chain_list *cl);
@@ -106,7 +111,7 @@ static inline void ocfs2_block_to_cluster_group(struct inode *inode,
 						u64 *bg_blkno,
 						u16 *bg_bit_off);
 
-void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
+static void ocfs2_free_ac_resource(struct ocfs2_alloc_context *ac)
 {
 	struct inode *inode = ac->ac_inode;
 
@@ -117,9 +122,17 @@ void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
 		mutex_unlock(&inode->i_mutex);
 
 		iput(inode);
+		ac->ac_inode = NULL;
 	}
-	if (ac->ac_bh)
+	if (ac->ac_bh) {
 		brelse(ac->ac_bh);
+		ac->ac_bh = NULL;
+	}
+}
+
+void ocfs2_free_alloc_context(struct ocfs2_alloc_context *ac)
+{
+	ocfs2_free_ac_resource(ac);
 	kfree(ac);
 }
 
@@ -391,7 +404,8 @@ bail:
 static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
 				       struct ocfs2_alloc_context *ac,
 				       int type,
-				       u32 slot)
+				       u32 slot,
+				       int alloc_new_group)
 {
 	int status;
 	u32 bits_wanted = ac->ac_bits_wanted;
@@ -420,6 +434,7 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
 	}
 
 	ac->ac_inode = alloc_inode;
+	ac->ac_alloc_slot = slot;
 
 	fe = (struct ocfs2_dinode *) bh->b_data;
 	if (!OCFS2_IS_VALID_DINODE(fe)) {
@@ -446,6 +461,14 @@ static int ocfs2_reserve_suballoc_bits(struct ocfs2_super *osb,
 			goto bail;
 		}
 
+		if (alloc_new_group != ALLOC_NEW_GROUP) {
+			mlog(0, "Alloc File %u Full: wanted=%u, free_bits=%u, "
+			     "and we don't alloc a new group for it.\n",
+			     slot, bits_wanted, free_bits);
+			status = -ENOSPC;
+			goto bail;
+		}
+
 		status = ocfs2_block_group_alloc(osb, alloc_inode, bh);
 		if (status < 0) {
 			if (status != -ENOSPC)
@@ -490,7 +513,8 @@ int ocfs2_reserve_new_metadata(struct ocfs2_super *osb,
 	(*ac)->ac_group_search = ocfs2_block_group_search;
 
 	status = ocfs2_reserve_suballoc_bits(osb, (*ac),
-					     EXTENT_ALLOC_SYSTEM_INODE, slot);
+					     EXTENT_ALLOC_SYSTEM_INODE,
+					     slot, ALLOC_NEW_GROUP);
 	if (status < 0) {
 		if (status != -ENOSPC)
 			mlog_errno(status);
@@ -508,10 +532,42 @@ bail:
 	return status;
 }
 
+static int ocfs2_steal_inode_from_other_nodes(struct ocfs2_super *osb,
+					      struct ocfs2_alloc_context *ac)
+{
+	int i, status = -ENOSPC;
+	s16 slot = ocfs2_get_inode_steal_slot(osb);
+
+	/* Start to steal inodes from the first slot after ours. */
+	if (slot == OCFS2_INVALID_SLOT)
+		slot = osb->slot_num + 1;
+
+	for (i = 0; i < osb->max_slots; i++, slot++) {
+		if (slot == osb->max_slots)
+			slot = 0;
+
+		if (slot == osb->slot_num)
+			continue;
+
+		status = ocfs2_reserve_suballoc_bits(osb, ac,
+						     INODE_ALLOC_SYSTEM_INODE,
+						     slot, NOT_ALLOC_NEW_GROUP);
+		if (status >= 0) {
+			ocfs2_set_inode_steal_slot(osb, slot);
+			break;
+		}
+
+		ocfs2_free_ac_resource(ac);
+	}
+
+	return status;
+}
+
 int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
 			    struct ocfs2_alloc_context **ac)
 {
 	int status;
+	s16 slot = ocfs2_get_inode_steal_slot(osb);
 
 	*ac = kzalloc(sizeof(struct ocfs2_alloc_context), GFP_KERNEL);
 	if (!(*ac)) {
@@ -525,9 +581,43 @@ int ocfs2_reserve_new_inode(struct ocfs2_super *osb,
 
 	(*ac)->ac_group_search = ocfs2_block_group_search;
 
+	/*
+	 * slot is set when we successfully steal inode from other nodes.
+	 * It is reset in 3 places:
+	 * 1. when we flush the truncate log
+	 * 2. when we complete local alloc recovery.
+	 * 3. when we successfully allocate from our own slot.
+	 * After it is set, we will go on stealing inodes until we find the
+	 * need to check our slots to see whether there is some space for us.
+	 */
+	if (slot != OCFS2_INVALID_SLOT &&
+	    atomic_read(&osb->s_num_inodes_stolen) < OCFS2_MAX_INODES_TO_STEAL)
+		goto inode_steal;
+
+	atomic_set(&osb->s_num_inodes_stolen, 0);
 	status = ocfs2_reserve_suballoc_bits(osb, *ac,
 					     INODE_ALLOC_SYSTEM_INODE,
-					     osb->slot_num);
+					     osb->slot_num, ALLOC_NEW_GROUP);
+	if (status >= 0) {
+		status = 0;
+
+		/*
+		 * Some inodes must be freed by us, so try to allocate
+		 * from our own next time.
+		 */
+		if (slot != OCFS2_INVALID_SLOT)
+			ocfs2_init_inode_steal_slot(osb);
+		goto bail;
+	} else if (status < 0 && status != -ENOSPC) {
+		mlog_errno(status);
+		goto bail;
+	}
+
+	ocfs2_free_ac_resource(*ac);
+
+inode_steal:
+	status = ocfs2_steal_inode_from_other_nodes(osb, *ac);
+	atomic_inc(&osb->s_num_inodes_stolen);
 	if (status < 0) {
 		if (status != -ENOSPC)
 			mlog_errno(status);
@@ -557,7 +647,8 @@ int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
 
 	status = ocfs2_reserve_suballoc_bits(osb, ac,
 					     GLOBAL_BITMAP_SYSTEM_INODE,
-					     OCFS2_INVALID_SLOT);
+					     OCFS2_INVALID_SLOT,
+					     ALLOC_NEW_GROUP);
 	if (status < 0 && status != -ENOSPC) {
 		mlog_errno(status);
 		goto bail;
diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index 8799033bb45..544c600662b 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -36,6 +36,7 @@ typedef int (group_search_t)(struct inode *,
 struct ocfs2_alloc_context {
 	struct inode *ac_inode;    /* which bitmap are we allocating from? */
 	struct buffer_head *ac_bh; /* file entry bh */
+	u32    ac_alloc_slot;   /* which slot are we allocating from? */
 	u32    ac_bits_wanted;
 	u32    ac_bits_given;
 #define OCFS2_AC_USE_LOCAL 1
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index bec75aff3d9..df63ba20ae9 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -40,8 +40,7 @@
 #include <linux/crc32.h>
 #include <linux/debugfs.h>
 #include <linux/mount.h>
-
-#include <cluster/nodemanager.h>
+#include <linux/seq_file.h>
 
 #define MLOG_MASK_PREFIX ML_SUPER
 #include <cluster/masklog.h>
@@ -88,6 +87,7 @@ struct mount_options
 	unsigned int	atime_quantum;
 	signed short	slot;
 	unsigned int	localalloc_opt;
+	char		cluster_stack[OCFS2_STACK_LABEL_LEN + 1];
 };
 
 static int ocfs2_parse_options(struct super_block *sb, char *options,
@@ -109,7 +109,6 @@ static int ocfs2_sync_fs(struct super_block *sb, int wait);
 static int ocfs2_init_global_system_inodes(struct ocfs2_super *osb);
 static int ocfs2_init_local_system_inodes(struct ocfs2_super *osb);
 static void ocfs2_release_system_inodes(struct ocfs2_super *osb);
-static int ocfs2_fill_local_node_info(struct ocfs2_super *osb);
 static int ocfs2_check_volume(struct ocfs2_super *osb);
 static int ocfs2_verify_volume(struct ocfs2_dinode *di,
 			       struct buffer_head *bh,
@@ -154,6 +153,7 @@ enum {
 	Opt_commit,
 	Opt_localalloc,
 	Opt_localflocks,
+	Opt_stack,
 	Opt_err,
 };
 
@@ -172,6 +172,7 @@ static match_table_t tokens = {
 	{Opt_commit, "commit=%u"},
 	{Opt_localalloc, "localalloc=%d"},
 	{Opt_localflocks, "localflocks"},
+	{Opt_stack, "cluster_stack=%s"},
 	{Opt_err, NULL}
 };
 
@@ -551,8 +552,17 @@ static int ocfs2_verify_heartbeat(struct ocfs2_super *osb)
 		}
 	}
 
+	if (ocfs2_userspace_stack(osb)) {
+		if (osb->s_mount_opt & OCFS2_MOUNT_HB_LOCAL) {
+			mlog(ML_ERROR, "Userspace stack expected, but "
+			     "o2cb heartbeat arguments passed to mount\n");
+			return -EINVAL;
+		}
+	}
+
 	if (!(osb->s_mount_opt & OCFS2_MOUNT_HB_LOCAL)) {
-		if (!ocfs2_mount_local(osb) && !ocfs2_is_hard_readonly(osb)) {
+		if (!ocfs2_mount_local(osb) && !ocfs2_is_hard_readonly(osb) &&
+		    !ocfs2_userspace_stack(osb)) {
 			mlog(ML_ERROR, "Heartbeat has to be started to mount "
 			     "a read-write clustered device.\n");
 			return -EINVAL;
@@ -562,6 +572,35 @@ static int ocfs2_verify_heartbeat(struct ocfs2_super *osb)
 	return 0;
 }
 
+/*
+ * If we're using a userspace stack, mount should have passed
+ * a name that matches the disk.  If not, mount should not
+ * have passed a stack.
+ */
+static int ocfs2_verify_userspace_stack(struct ocfs2_super *osb,
+					struct mount_options *mopt)
+{
+	if (!ocfs2_userspace_stack(osb) && mopt->cluster_stack[0]) {
+		mlog(ML_ERROR,
+		     "cluster stack passed to mount, but this filesystem "
+		     "does not support it\n");
+		return -EINVAL;
+	}
+
+	if (ocfs2_userspace_stack(osb) &&
+	    strncmp(osb->osb_cluster_stack, mopt->cluster_stack,
+		    OCFS2_STACK_LABEL_LEN)) {
+		mlog(ML_ERROR,
+		     "cluster stack passed to mount (\"%s\") does not "
+		     "match the filesystem (\"%s\")\n",
+		     mopt->cluster_stack,
+		     osb->osb_cluster_stack);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct dentry *root;
@@ -579,15 +618,6 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 		goto read_super_error;
 	}
 
-	/* for now we only have one cluster/node, make sure we see it
-	 * in the heartbeat universe */
-	if (parsed_options.mount_opt & OCFS2_MOUNT_HB_LOCAL) {
-		if (!o2hb_check_local_node_heartbeating()) {
-			status = -EINVAL;
-			goto read_super_error;
-		}
-	}
-
 	/* probe for superblock */
 	status = ocfs2_sb_probe(sb, &bh, &sector_size);
 	if (status < 0) {
@@ -609,6 +639,10 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 	osb->osb_commit_interval = parsed_options.commit_interval;
 	osb->local_alloc_size = parsed_options.localalloc_opt;
 
+	status = ocfs2_verify_userspace_stack(osb, &parsed_options);
+	if (status)
+		goto read_super_error;
+
 	sb->s_magic = OCFS2_SUPER_MAGIC;
 
 	/* Hard readonly mode only if: bdev_read_only, MS_RDONLY,
@@ -694,7 +728,7 @@ static int ocfs2_fill_super(struct super_block *sb, void *data, int silent)
 	if (ocfs2_mount_local(osb))
 		snprintf(nodestr, sizeof(nodestr), "local");
 	else
-		snprintf(nodestr, sizeof(nodestr), "%d", osb->node_num);
+		snprintf(nodestr, sizeof(nodestr), "%u", osb->node_num);
 
 	printk(KERN_INFO "ocfs2: Mounting device (%s) on (node %s, slot %d) "
 	       "with %s data mode.\n",
@@ -763,6 +797,7 @@ static int ocfs2_parse_options(struct super_block *sb,
 	mopt->atime_quantum = OCFS2_DEFAULT_ATIME_QUANTUM;
 	mopt->slot = OCFS2_INVALID_SLOT;
 	mopt->localalloc_opt = OCFS2_DEFAULT_LOCAL_ALLOC_SIZE;
+	mopt->cluster_stack[0] = '\0';
 
 	if (!options) {
 		status = 1;
@@ -864,6 +899,25 @@ static int ocfs2_parse_options(struct super_block *sb,
 			if (!is_remount)
 				mopt->mount_opt |= OCFS2_MOUNT_LOCALFLOCKS;
 			break;
+		case Opt_stack:
+			/* Check both that the option we were passed
+			 * is of the right length and that it is a proper
+			 * string of the right length.
+			 */
+			if (((args[0].to - args[0].from) !=
+			     OCFS2_STACK_LABEL_LEN) ||
+			    (strnlen(args[0].from,
+				     OCFS2_STACK_LABEL_LEN) !=
+			     OCFS2_STACK_LABEL_LEN)) {
+				mlog(ML_ERROR,
+				     "Invalid cluster_stack option\n");
+				status = 0;
+				goto bail;
+			}
+			memcpy(mopt->cluster_stack, args[0].from,
+			       OCFS2_STACK_LABEL_LEN);
+			mopt->cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0';
+			break;
 		default:
 			mlog(ML_ERROR,
 			     "Unrecognized mount option \"%s\" "
@@ -922,6 +976,10 @@ static int ocfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
 	if (opts & OCFS2_MOUNT_LOCALFLOCKS)
 		seq_printf(s, ",localflocks,");
 
+	if (osb->osb_cluster_stack[0])
+		seq_printf(s, ",cluster_stack=%.*s", OCFS2_STACK_LABEL_LEN,
+			   osb->osb_cluster_stack);
+
 	return 0;
 }
 
@@ -957,6 +1015,8 @@ static int __init ocfs2_init(void)
 		mlog(ML_ERROR, "Unable to create ocfs2 debugfs root.\n");
 	}
 
+	ocfs2_set_locking_protocol();
+
 leave:
 	if (status < 0) {
 		ocfs2_free_mem_caches();
@@ -1132,31 +1192,6 @@ static int ocfs2_get_sector(struct super_block *sb,
 	return 0;
 }
 
-/* ocfs2 1.0 only allows one cluster and node identity per kernel image. */
-static int ocfs2_fill_local_node_info(struct ocfs2_super *osb)
-{
-	int status;
-
-	/* XXX hold a ref on the node while mounte?  easy enough, if
-	 * desirable. */
-	if (ocfs2_mount_local(osb))
-		osb->node_num = 0;
-	else
-		osb->node_num = o2nm_this_node();
-
-	if (osb->node_num == O2NM_MAX_NODES) {
-		mlog(ML_ERROR, "could not find this host's node number\n");
-		status = -ENOENT;
-		goto bail;
-	}
-
-	mlog(0, "I am node %d\n", osb->node_num);
-
-	status = 0;
-bail:
-	return status;
-}
-
 static int ocfs2_mount_volume(struct super_block *sb)
 {
 	int status = 0;
@@ -1168,12 +1203,6 @@ static int ocfs2_mount_volume(struct super_block *sb)
 	if (ocfs2_is_hard_readonly(osb))
 		goto leave;
 
-	status = ocfs2_fill_local_node_info(osb);
-	if (status < 0) {
-		mlog_errno(status);
-		goto leave;
-	}
-
 	status = ocfs2_dlm_init(osb);
 	if (status < 0) {
 		mlog_errno(status);
@@ -1224,18 +1253,9 @@ leave:
 	return status;
 }
 
-/* we can't grab the goofy sem lock from inside wait_event, so we use
- * memory barriers to make sure that we'll see the null task before
- * being woken up */
-static int ocfs2_recovery_thread_running(struct ocfs2_super *osb)
-{
-	mb();
-	return osb->recovery_thread_task != NULL;
-}
-
 static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 {
-	int tmp;
+	int tmp, hangup_needed = 0;
 	struct ocfs2_super *osb = NULL;
 	char nodestr[8];
 
@@ -1249,25 +1269,16 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 
 	ocfs2_truncate_log_shutdown(osb);
 
-	/* disable any new recovery threads and wait for any currently
-	 * running ones to exit. Do this before setting the vol_state. */
-	mutex_lock(&osb->recovery_lock);
-	osb->disable_recovery = 1;
-	mutex_unlock(&osb->recovery_lock);
-	wait_event(osb->recovery_event, !ocfs2_recovery_thread_running(osb));
-
-	/* At this point, we know that no more recovery threads can be
-	 * launched, so wait for any recovery completion work to
-	 * complete. */
-	flush_workqueue(ocfs2_wq);
+	/* This will disable recovery and flush any recovery work. */
+	ocfs2_recovery_exit(osb);
 
 	ocfs2_journal_shutdown(osb);
 
 	ocfs2_sync_blockdev(sb);
 
-	/* No dlm means we've failed during mount, so skip all the
-	 * steps which depended on that to complete. */
-	if (osb->dlm) {
+	/* No cluster connection means we've failed during mount, so skip
+	 * all the steps which depended on that to complete. */
+	if (osb->cconn) {
 		tmp = ocfs2_super_lock(osb, 1);
 		if (tmp < 0) {
 			mlog_errno(tmp);
@@ -1278,25 +1289,34 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 	if (osb->slot_num != OCFS2_INVALID_SLOT)
 		ocfs2_put_slot(osb);
 
-	if (osb->dlm)
+	if (osb->cconn)
 		ocfs2_super_unlock(osb, 1);
 
 	ocfs2_release_system_inodes(osb);
 
-	if (osb->dlm)
-		ocfs2_dlm_shutdown(osb);
+	/*
+	 * If we're dismounting due to mount error, mount.ocfs2 will clean
+	 * up heartbeat.  If we're a local mount, there is no heartbeat.
+	 * If we failed before we got a uuid_str yet, we can't stop
+	 * heartbeat.  Otherwise, do it.
+	 */
+	if (!mnt_err && !ocfs2_mount_local(osb) && osb->uuid_str)
+		hangup_needed = 1;
+
+	if (osb->cconn)
+		ocfs2_dlm_shutdown(osb, hangup_needed);
 
 	debugfs_remove(osb->osb_debug_root);
 
-	if (!mnt_err)
-		ocfs2_stop_heartbeat(osb);
+	if (hangup_needed)
+		ocfs2_cluster_hangup(osb->uuid_str, strlen(osb->uuid_str));
 
 	atomic_set(&osb->vol_state, VOLUME_DISMOUNTED);
 
 	if (ocfs2_mount_local(osb))
 		snprintf(nodestr, sizeof(nodestr), "local");
 	else
-		snprintf(nodestr, sizeof(nodestr), "%d", osb->node_num);
+		snprintf(nodestr, sizeof(nodestr), "%u", osb->node_num);
 
 	printk(KERN_INFO "ocfs2: Unmounting device (%s) on (node %s)\n",
 	       osb->dev_str, nodestr);
@@ -1355,7 +1375,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	sb->s_fs_info = osb;
 	sb->s_op = &ocfs2_sops;
 	sb->s_export_op = &ocfs2_export_ops;
-	osb->osb_locking_proto = ocfs2_locking_protocol;
 	sb->s_time_gran = 1;
 	sb->s_flags |= MS_NOATIME;
 	/* this is needed to support O_LARGEFILE */
@@ -1368,7 +1387,6 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	osb->s_sectsize_bits = blksize_bits(sector_size);
 	BUG_ON(!osb->s_sectsize_bits);
 
-	init_waitqueue_head(&osb->recovery_event);
 	spin_lock_init(&osb->dc_task_lock);
 	init_waitqueue_head(&osb->dc_event);
 	osb->dc_work_sequence = 0;
@@ -1376,6 +1394,7 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	INIT_LIST_HEAD(&osb->blocked_lock_list);
 	osb->blocked_lock_count = 0;
 	spin_lock_init(&osb->osb_lock);
+	ocfs2_init_inode_steal_slot(osb);
 
 	atomic_set(&osb->alloc_stats.moves, 0);
 	atomic_set(&osb->alloc_stats.local_data, 0);
@@ -1388,24 +1407,23 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	snprintf(osb->dev_str, sizeof(osb->dev_str), "%u,%u",
 		 MAJOR(osb->sb->s_dev), MINOR(osb->sb->s_dev));
 
-	mutex_init(&osb->recovery_lock);
-
-	osb->disable_recovery = 0;
-	osb->recovery_thread_task = NULL;
+	status = ocfs2_recovery_init(osb);
+	if (status) {
+		mlog(ML_ERROR, "Unable to initialize recovery state\n");
+		mlog_errno(status);
+		goto bail;
+	}
 
 	init_waitqueue_head(&osb->checkpoint_event);
 	atomic_set(&osb->needs_checkpoint, 0);
 
 	osb->s_atime_quantum = OCFS2_DEFAULT_ATIME_QUANTUM;
 
-	osb->node_num = O2NM_INVALID_NODE_NUM;
 	osb->slot_num = OCFS2_INVALID_SLOT;
 
 	osb->local_alloc_state = OCFS2_LA_UNUSED;
 	osb->local_alloc_bh = NULL;
 
-	ocfs2_setup_hb_callbacks(osb);
-
 	init_waitqueue_head(&osb->osb_mount_event);
 
 	osb->vol_label = kmalloc(OCFS2_MAX_VOL_LABEL_LEN, GFP_KERNEL);
@@ -1455,6 +1473,25 @@ static int ocfs2_initialize_super(struct super_block *sb,
 		goto bail;
 	}
 
+	if (ocfs2_userspace_stack(osb)) {
+		memcpy(osb->osb_cluster_stack,
+		       OCFS2_RAW_SB(di)->s_cluster_info.ci_stack,
+		       OCFS2_STACK_LABEL_LEN);
+		osb->osb_cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0';
+		if (strlen(osb->osb_cluster_stack) != OCFS2_STACK_LABEL_LEN) {
+			mlog(ML_ERROR,
+			     "couldn't mount because of an invalid "
+			     "cluster stack label (%s) \n",
+			     osb->osb_cluster_stack);
+			status = -EINVAL;
+			goto bail;
+		}
+	} else {
+		/* The empty string is identical with classic tools that
+		 * don't know about s_cluster_info. */
+		osb->osb_cluster_stack[0] = '\0';
+	}
+
 	get_random_bytes(&osb->s_next_generation, sizeof(u32));
 
 	/* FIXME
@@ -1724,8 +1761,7 @@ static void ocfs2_delete_osb(struct ocfs2_super *osb)
 
 	/* This function assumes that the caller has the main osb resource */
 
-	if (osb->slot_info)
-		ocfs2_free_slot_info(osb->slot_info);
+	ocfs2_free_slot_info(osb);
 
 	kfree(osb->osb_orphan_wipes);
 	/* FIXME
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 5f66c446615..817f5966edc 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -87,7 +87,14 @@ int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char
 
 void sysfs_remove_link(struct kobject * kobj, const char * name)
 {
-	sysfs_hash_and_remove(kobj->sd, name);
+	struct sysfs_dirent *parent_sd = NULL;
+
+	if (!kobj)
+		parent_sd = &sysfs_root;
+	else
+		parent_sd = kobj->sd;
+
+	sysfs_hash_and_remove(parent_sd, name);
 }
 
 static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,