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 <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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@ -2275,9 +2275,8 @@ static int create_cache_policy(struct cache *cache, struct cache_args *ca,
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}
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/*
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* We want the discard block size to be a power of two, at least the size
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* of the cache block size, and have no more than 2^14 discard blocks
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* across the origin.
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* We want the discard block size to be at least the size of the cache
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* block size and have no more than 2^14 discard blocks across the origin.
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*/
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#define MAX_DISCARD_BLOCKS (1 << 14)
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@ -2292,9 +2291,7 @@ static bool too_many_discard_blocks(sector_t discard_block_size,
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static sector_t calculate_discard_block_size(sector_t cache_block_size,
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sector_t origin_size)
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{
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sector_t discard_block_size;
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discard_block_size = roundup_pow_of_two(cache_block_size);
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sector_t discard_block_size = cache_block_size;
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if (origin_size)
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while (too_many_discard_blocks(discard_block_size, origin_size))
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