diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 66dbc8d..7ba7b39 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -465,7 +465,11 @@
 	 * flush all outstanding I/O and inode extent mappings before the
 	 * copy operation is declared as being finished
 	 */
-	btrfs_start_delalloc_inodes(root, 0);
+	ret = btrfs_start_delalloc_inodes(root, 0);
+	if (ret) {
+		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
+		return ret;
+	}
 	btrfs_wait_ordered_extents(root, 0);
 
 	trans = btrfs_start_transaction(root, 0);