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Commit 2bb812df authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
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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: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 43c32bf2

drivers/md/dm-cache-target.c

+3 −6
Original line number Original line Diff line number Diff line
@@ -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

 * We want the discard block size to be at least the size of the cache

 * of the cache block size, and have no more than 2^14 discard blocks

 * block size and have no more than 2^14 discard blocks across the origin.

 * across the origin.

 */

 */

#define MAX_DISCARD_BLOCKS (1 << 14)

#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,

static sector_t calculate_discard_block_size(sector_t cache_block_size,

					     sector_t origin_size)

					     sector_t origin_size)

{

{

	sector_t discard_block_size;

	sector_t discard_block_size = cache_block_size;



	discard_block_size = roundup_pow_of_two(cache_block_size);





	if (origin_size)

	if (origin_size)

		while (too_many_discard_blocks(discard_block_size, origin_size))

		while (too_many_discard_blocks(discard_block_size, origin_size))