Commit 449b668c authored Mar 31, 2017 by Joe Thornber Committed by Mike Snitzer Mar 31, 2017

dm cache: set/clear the cache core's dirty_bitset when loading mappings

When loading metadata make sure to set/clear the dirty bits in the cache
core's dirty_bitset as well as the policy.

Otherwise the cache core is unaware that any blocks were dirty when the
cache was last shutdown. A very serious side-effect being that the
cleaner policy would therefore never be tasked with writing back dirty
data from a cache that was in writeback mode (e.g. when switching from
smq policy to cleaner policy when decommissioning a writeback cache).

This fixes a serious data corruption bug associated with writeback mode.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

parent 7b81ef8b

drivers/md/dm-cache-target.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -2960,6 +2960,12 @@ static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
		int r;
		struct cache *cache = context;

		if (dirty) {
		set_bit(from_cblock(cblock), cache->dirty_bitset);
		atomic_inc(&cache->nr_dirty);
		} else
		clear_bit(from_cblock(cblock), cache->dirty_bitset);

		r = policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
		if (r)
		return r;