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

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This reverts commit d132cc6d9e 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: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2014-11-06 14:38:01 +00:00 committed by Mike Snitzer
parent 1bad9bc4ee
commit 08b184514f
1 changed files with 34 additions and 3 deletions
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37
drivers/md/dm-cache-target.c
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@ -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;
}