dm cache: dirty flag was mistakenly being cleared when promoting via overwrite

If the incoming bio is a WRITE and completely covers a block then we
don't bother to do any copying for a promotion operation.  Once this is
done the cache block and origin block will be different, so we need to
set it to 'dirty'.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index ef842feda101..1a090de0c4b8 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -988,10 +988,14 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
                 }
 
         } else {
-                clear_dirty(cache, mg->new_oblock, mg->cblock);
-                if (mg->requeue_holder)
+                if (mg->requeue_holder) {
+                        clear_dirty(cache, mg->new_oblock, mg->cblock);
                         cell_defer(cache, mg->new_ocell, true);
-                else {
+                } else {
+                        /*
+                         * The block was promoted via an overwrite, so it's dirty.
+                         */
+                        set_dirty(cache, mg->new_oblock, mg->cblock);
                         bio_endio(mg->new_ocell->holder, 0);
                         cell_defer(cache, mg->new_ocell, false);
                 }