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>

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index b7de289a10bb64ad35ae93089ce0bd93f650734c..6e747fcbdf0f88a4a6c4f6c5e25e3c3fa0795a37 100644 (file)
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -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;