btrfs: return errors from btrfs_del_csums in cleanup_ref_head

We are unconditionally returning 0 in cleanup_ref_head, despite the fact
that btrfs_del_csums could fail.  We need to return the error so the
transaction gets aborted properly, fix this by returning ret from
btrfs_del_csums in cleanup_ref_head.
Reviewed-by: NQu Wenruo <wqu@suse.com>
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -1868,7 +1868,7 @@ static int cleanup_ref_head(struct btrfs_trans_handle *trans,
 	trace_run_delayed_ref_head(fs_info, head, 0);
 	btrfs_delayed_ref_unlock(head);
 	btrfs_put_delayed_ref_head(head);
-	return 0;
+	return ret;
 }
 
 static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(