Merge tag 'dm-3.17-fix2' of git://git.kernel.org/pub/scm/linux/kernel…

…/git/device-mapper/linux-dm

Pull device mapper fix from Mike Snitzer:
 "Fix a race in the DM cache target that caused dirty blocks to be
  marked as clean.  This could cause no writeback to occur or spurious
  dirty block counts"

* tag 'dm-3.17-fix2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm cache: fix race causing dirty blocks to be marked as clean

drivers/md/dm-cache-target.c

@@ -895,8 +895,8 @@ static void migration_success_pre_commit(struct dm_cache_migration *mg)
 	struct cache *cache = mg->cache;
 
 	if (mg->writeback) {
-		cell_defer(cache, mg->old_ocell, false);
 		clear_dirty(cache, mg->old_oblock, mg->cblock);
+		cell_defer(cache, mg->old_ocell, false);
 		cleanup_migration(mg);
 		return;
 
@@ -951,13 +951,13 @@ static void migration_success_post_commit(struct dm_cache_migration *mg)
 		}
 
 	} else {
+		clear_dirty(cache, mg->new_oblock, mg->cblock);
 		if (mg->requeue_holder)
 			cell_defer(cache, mg->new_ocell, true);
 		else {
 			bio_endio(mg->new_ocell->holder, 0);
 			cell_defer(cache, mg->new_ocell, false);
 		}
-		clear_dirty(cache, mg->new_oblock, mg->cblock);
 		cleanup_migration(mg);
 	}
 }