[PATCH 2/3] xfs: only end a COW operation in xfs_zero_remaining_bytes if we started one

[Christoph Hellwig]

Without these we can see NULL pointer dereferences due to a non-existing
COW fork during xfstests runs.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 fs/xfs/xfs_bmap_util.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 7bee3c7..e777095 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1226,13 +1226,15 @@ xfs_zero_remaining_bytes(
 
 		error = xfs_bwrite(bp);
 		xfs_buf_relse(bp);
-		if (error) {
-			err2 = xfs_reflink_end_cow_failed(ip, offset,
+		if (should_fork) {
+			if (error) {
+				err2 = xfs_reflink_end_cow_failed(ip, offset,
+						lastoffset - offset + 1);
+				return error;
+			}
+			error = xfs_reflink_end_cow(ip, offset,
 					lastoffset - offset + 1);
-			return error;
 		}
-		error = xfs_reflink_end_cow(ip, offset,
-				lastoffset - offset + 1);
 		if (error)
 			return error;
 	}
-- 
1.9.1