kernel/dm-cache-only-use-overwrite-optimisation-for-promoti.patch

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2014-12-18 15:06:55 +00:00
From: Joe Thornber <ejt@redhat.com>
Date: Thu, 27 Nov 2014 12:21:08 +0000
Subject: [PATCH] dm cache: only use overwrite optimisation for promotion when
in writeback mode
Overwrite causes the cache block and origin blocks to diverge, which
is only allowed in writeback mode.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
---
drivers/md/dm-cache-target.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 7130505c2425..6f7086355691 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -1070,7 +1070,8 @@ static void issue_copy(struct dm_cache_migration *mg)
avoid = is_discarded_oblock(cache, mg->new_oblock);
- if (!avoid && bio_writes_complete_block(cache, bio)) {
+ if (writeback_mode(&cache->features) &&
+ !avoid && bio_writes_complete_block(cache, bio)) {
issue_overwrite(mg, bio);
return;
}
--
2.1.0