Btrfs: remove ourselves from the cluster list under lock

commit b8d0c69b9469ffd33df30fee3e990f2d4aa68a09 upstream.

A user was reporting weird warnings from btrfs_put_delayed_ref() and I noticed
that we were doing this list_del_init() on our head ref outside of
delayed_refs->lock.  This is a problem if we have people still on the list, we
could end up modifying old pointers and such.  Fix this by removing us from the
list before we do our run_delayed_ref on our head ref.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0b272d0683370ec8288fad1bb3e9aaf56839ad73..3b6d20bc2388eeafb6a823ca9a559c93d7ac2fab 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2402,6 +2402,8 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                        default:
                                WARN_ON(1);
                        }
+               } else {
+                       list_del_init(&locked_ref->cluster);
                }
                spin_unlock(&delayed_refs->lock);
 
@@ -2424,7 +2426,6 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans,
                 * list before we release it.
                 */
                if (btrfs_delayed_ref_is_head(ref)) {
-                       list_del_init(&locked_ref->cluster);
                        btrfs_delayed_ref_unlock(locked_ref);
                        locked_ref = NULL;
                }