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
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index fd7f613..ef842fe 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -1142,7 +1142,8 @@
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;
}