Commit d2adffd7 authored Oct 09, 2015 by Joe Thornber Committed by Sasha Levin Oct 27, 2015

dm cache: fix NULL pointer when switching from cleaner policy



[ Upstream commit 2bffa1503c5c06192eb1459180fac4416575a966 ]

The cleaner policy doesn't make use of the per cache block hint space in
the metadata (unlike the other policies).  When switching from the
cleaner policy to mq or smq a NULL pointer crash (in dm_tm_new_block)
was observed.  The crash was caused by bugs in dm-cache-metadata.c
when trying to skip creation of the hint btree.

The minimal fix is to change hint size for the cleaner policy to 4 bytes
(only hint size supported).

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

parent 5b0d0df8

drivers/md/dm-cache-policy-cleaner.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -434,7 +434,7 @@ static struct dm_cache_policy *wb_create(dm_cblock_t cache_size,
		static struct dm_cache_policy_type wb_policy_type = {
		.name = "cleaner",
		.version = {1, 0, 0},
		.hint_size = 0,
		.hint_size = 4,
		.owner = THIS_MODULE,
		.create = wb_create
		};