[096/251] Btrfs: fix lock leak when resuming snapshot deletion

[Steven Rostedt]

3.6.11.9-rc1 stable review patch.
If anyone has any objections, please let me know.

------------------

From: Josef Bacik <jbacik@xxxxxxxxxxxx>

[ Upstream commit fec386ac1428f9c0e672df952cbca5cebd4e4e2f ]

We aren't setting path->locks[level] when we resume a snapshot deletion which
means we won't unlock the buffer when we free the path.  This causes deadlocks
if we happen to re-allocate the block before we've evicted the extent buffer
from cache.  Thanks,

Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Alex Lyakas <alex.btrfs@xxxxxxxxxxxxxxxxx>
Signed-off-by: Josef Bacik <jbacik@xxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 fs/btrfs/extent-tree.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 6d7b589..dcfce2a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7007,6 +7007,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 		while (1) {
 			btrfs_tree_lock(path->nodes[level]);
 			btrfs_set_lock_blocking(path->nodes[level]);
+			path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
 
 			ret = btrfs_lookup_extent_info(trans, root,
 						path->nodes[level]->start,
@@ -7023,6 +7024,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 				break;
 
 			btrfs_tree_unlock(path->nodes[level]);
+			path->locks[level] = 0;
 			WARN_ON(wc->refs[level] != 1);
 			level--;
 		}
-- 
1.7.10.4


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