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

[Christoph Hellwig <hch@xxxxxx>]

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

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 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