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dm cache: fix NULL pointer when switching from cleaner policy

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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
This commit is contained in:
Joe Thornber 2015-10-09 14:03:38 +01:00 committed by Mike Snitzer
parent 50887bd139
commit 2bffa1503c
1 changed files with 1 additions and 1 deletions
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2
drivers/md/dm-cache-policy-cleaner.c
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@ -436,7 +436,7 @@ 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
};