+ if (!mutex_trylock(&head->mutex)) {
+ atomic_inc(&ref->refs);
+ spin_unlock(&delayed_refs->lock);
+
+ /* Need to wait for the delayed ref to run */
+ mutex_lock(&head->mutex);
+ mutex_unlock(&head->mutex);
+ btrfs_put_delayed_ref(ref);
+
+ spin_lock(&delayed_refs->lock);
+ continue;
+ }
+