Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 08b18451 authored by Joe Thornber's avatar Joe Thornber Committed by Mike Snitzer
Browse files

dm cache: revert "prevent corruption caused by discard_block_size > cache_block_size" 



This reverts commit d132cc6d because we
actually do want to allow the discard blocksize to be larger than the
cache blocksize.  Further dm-cache discard changes will make this
possible.

Signed-off-by: default avatarJoe Thornber <ejt@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 1bad9bc4

drivers/md/dm-cache-target.c

+34 −3
Original line number Diff line number Diff line
@@ -238,7 +238,7 @@ struct cache { 
	 */

	dm_dblock_t discard_nr_blocks;

	unsigned long *discard_bitset;

	uint32_t discard_block_size;

	uint32_t discard_block_size; /* a power of 2 times sectors per block */



	/*

	 * Rather than reconstructing the table line for the status we just
@@ -2197,6 +2197,35 @@ static int create_cache_policy(struct cache *cache, struct cache_args *ca, 
	return 0;

}



/*

 * 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.

 */

#define MAX_DISCARD_BLOCKS (1 << 14)



static bool too_many_discard_blocks(sector_t discard_block_size,

				    sector_t origin_size)

{

	(void) sector_div(origin_size, discard_block_size);



	return origin_size > MAX_DISCARD_BLOCKS;

}



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);



	if (origin_size)

		while (too_many_discard_blocks(discard_block_size, origin_size))

			discard_block_size *= 2;



	return discard_block_size;

}



#define DEFAULT_MIGRATION_THRESHOLD 2048



static int cache_create(struct cache_args *ca, struct cache **result)
@@ -2320,7 +2349,9 @@ static int cache_create(struct cache_args *ca, struct cache **result) 
	}

	clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));



	cache->discard_block_size = cache->sectors_per_block;

	cache->discard_block_size =

		calculate_discard_block_size(cache->sectors_per_block,

					     cache->origin_sectors);

	cache->discard_nr_blocks = oblock_to_dblock(cache, cache->origin_blocks);

	cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));

	if (!cache->discard_bitset) {
@@ -3099,7 +3130,7 @@ static void set_discard_limits(struct cache *cache, struct queue_limits *limits) 
	/*

	 * FIXME: these limits may be incompatible with the cache device

	 */

	limits->max_discard_sectors = cache->discard_block_size;

	limits->max_discard_sectors = cache->discard_block_size * 1024;

	limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;

}