Patch "dm btree: fix bufio buffer leaks in dm_btree_del() error path" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

dm btree: fix bufio buffer leaks in dm_btree_del() error path

to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dm-btree-fix-bufio-buffer-leaks-in-dm_btree_del-error-path.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Joe Thornber <[email protected]>
Date: Thu, 10 Dec 2015 14:37:53 +0000
Subject: dm btree: fix bufio buffer leaks in dm_btree_del() error path

From: Joe Thornber <[email protected]>

commit ed8b45a3679eb49069b094c0711b30833f27c734 upstream.

If dm_btree_del()'s call to push_frame() fails, e.g. due to btree_node_validator finding invalid metadata, the dm_btree_del() error path must unlock all frames (which have active dm-bufio buffers) that were pushed onto the del_stack.

Otherwise, dm_bufio_client_destroy() will BUG_ON() because dm-bufio buffers have leaked, e.g.:
device-mapper: bufio: leaked buffer 3, hold count 1, list 0

---
 drivers/md/persistent-data/dm-btree.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

@@ -250,6 +250,16 @@ static void pop_frame(struct del_stack *
 	dm_tm_unlock(s->tm, f->b);
 }
 
+static void unlock_all_frames(struct del_stack *s)
+{
+	struct frame *f;
+
+	while (unprocessed_frames(s)) {
+		f = s->spine + s->top--;
+		dm_tm_unlock(s->tm, f->b);
+	}
+}
+
 int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
 {
 	int r;

@@ -306,9 +316,13 @@ int dm_btree_del(struct dm_btree_info *i
 			pop_frame(s);
 		}
 	}
-
 out:
+	if (r) {
+		/* cleanup all frames of del_stack */
+		unlock_all_frames(s);
+	}
 	kfree(s);
+
 	return r;
 }
 EXPORT_SYMBOL_GPL(dm_btree_del);

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/dm-thin-restore-requested-error_if_no_space-setting-on-oods-to-write-transition.patch queue-3.14/dm-space-map-metadata-fix-ref-counting-bug-when-bootstrapping-a-new-space-map.patch queue-3.14/dm-btree-fix-bufio-buffer-leaks-in-dm_btree_del-error-path.patch queue-3.14/dm-thin-metadata-fix-bug-when-taking-a-metadata-snapshot.patch