From d2adffd701eefc29c06cd10494e4bdb2bc70fe3b Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Fri, 9 Oct 2015 14:03:38 +0100 Subject: [PATCH] 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 Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin --- drivers/md/dm-cache-policy-cleaner.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-cache-policy-cleaner.c b/drivers/md/dm-cache-policy-cleaner.c index b04d1f904d07..2eca9084defe 100644 --- a/drivers/md/dm-cache-policy-cleaner.c +++ b/drivers/md/dm-cache-policy-cleaner.c @@ -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 };