btrfs: handle btrfs_del_item errors in __btrfs_update_delayed_inode

Even if the slot is already read out, we may still need to re-balance
the tree, thus it can cause error in that btrfs_del_item() call and we
need to handle it properly.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: void0red <void0red@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-inode.c

@@ -1048,7 +1048,7 @@ static int __btrfs_update_delayed_inode(struct btrfs_trans_handle *trans,
 	 * so there is only one iref. The case that several irefs are
 	 * in the same item doesn't exist.
 	 */
-	btrfs_del_item(trans, root, path);
+	ret = btrfs_del_item(trans, root, path);
 out:
 	btrfs_release_delayed_iref(node);
 	btrfs_release_path(path);