md: revert change to raid_disks on failure.

If we try to update_raid_disks and it fails, we should put
'delta_disks' back to zero.  This is important because some code,
such as slot_store, assumes that delta_disks has been validated.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index b76cfc89e1b5..e636e404e9a5 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5578,6 +5578,8 @@ static int update_raid_disks(mddev_t *mddev, int raid_disks)
         mddev->delta_disks = raid_disks - mddev->raid_disks;
 
         rv = mddev->pers->check_reshape(mddev);
+        if (rv < 0)
+                mddev->delta_disks = 0;
         return rv;
 }