From 2bb812df63bbd246bd39d10f2e810b2a0a59e99e Mon Sep 17 00:00:00 2001 From: Joe Thornber Date: Wed, 26 Nov 2014 16:07:50 +0000 Subject: [PATCH] dm cache: discard block size must be a multiple of cache block size Otherwise the cache blocks may span two discard blocks, which we don't handle when doing the discard lookup. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer --- drivers/md/dm-cache-target.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 161bbd6652f8..fd7f61387283 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2275,9 +2275,8 @@ static int create_cache_policy(struct cache *cache, struct cache_args *ca, } /* - * We want the discard block size to be a power of two, at least the size - * of the cache block size, and have no more than 2^14 discard blocks - * across the origin. + * We want the discard block size to be at least the size of the cache + * block size and have no more than 2^14 discard blocks across the origin. */ #define MAX_DISCARD_BLOCKS (1 << 14) @@ -2292,9 +2291,7 @@ static bool too_many_discard_blocks(sector_t discard_block_size, static sector_t calculate_discard_block_size(sector_t cache_block_size, sector_t origin_size) { - sector_t discard_block_size; - - discard_block_size = roundup_pow_of_two(cache_block_size); + sector_t discard_block_size = cache_block_size; if (origin_size) while (too_many_discard_blocks(discard_block_size, origin_size)) -- 2.30.2