[PATCH 4.19 03/18] btrfs: add missing mutex_unlock in btrfs_relocate_sys_chunks()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Dominique Martinet <dominique.martinet@atmark-techno.com>

commit 9af503d91298c3f2945e73703f0e00995be08c30 upstream.

The previous patch that replaced BUG_ON by error handling forgot to
unlock the mutex in the error path.

Link: https://lore.kernel.org/all/Zh%2fHpAGFqa7YAFuM@duo.ucw.cz
Reported-by: Pavel Machek <pavel@denx.de>
Fixes: 7411055db5ce ("btrfs: handle chunk tree lookup error in btrfs_relocate_sys_chunks()")
CC: stable@vger.kernel.org
Reviewed-by: Pavel Machek <pavel@denx.de>
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/btrfs/volumes.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2957,6 +2957,7 @@ again:
 			 * alignment and size).
 			 */
 			ret = -EUCLEAN;
+			mutex_unlock(&fs_info->delete_unused_bgs_mutex);
 			goto error;
 		}