From: Joe Thornber <ejt@redhat.com>
Date: Thu, 27 Nov 2014 12:26:46 +0000 (+0000)
Subject: dm cache: dirty flag was mistakenly being cleared when promoting via overwrite
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=1e32134a5a404e80bfb47fad8a94e9bbfcbdacc5;p=openwrt%2Fstaging%2Fblogic.git

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
---

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);
 		}