xfs: cancel dfops on xfs_defer_finish() error

The current semantics of xfs_defer_finish() require the caller to
call xfs_defer_cancel() on error. This is slightly inconsistent with
transaction commit error handling where a failed commit cleans up
the transaction before returning.

More significantly, the only requirement for exposure of
->dop_pending outside of xfs_defer_finish() is so that
xfs_defer_cancel() can drain it on error. Since the only recourse of
xfs_defer_finish() errors is cancellation, mirror the transaction
logic and cancel remaining dfops before returning from
xfs_defer_finish() with an error.

Beside simplifying xfs_defer_finish() semantics, this ensures that
xfs_defer_finish() always returns with an empty ->dop_pending and
thus facilitates removal of the list from xfs_defer_ops.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 7079f534c735..b656a399cd71 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -416,14 +416,15 @@ xfs_defer_finish_noroll(
 	}
 
 out:
-	if (error)
+	if (error) {
 		trace_xfs_defer_finish_error((*tp)->t_mountp, (*tp)->t_dfops,
 					     error);
-	 else
-		trace_xfs_defer_finish_done((*tp)->t_mountp, (*tp)->t_dfops,
-					    _RET_IP_);
+		xfs_defer_cancel(*tp);
+		return error;
+	}
 
-	return error;
+	trace_xfs_defer_finish_done((*tp)->t_mountp, (*tp)->t_dfops, _RET_IP_);
+	return 0;
 }
 
 int