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authorJoe Thornber <ejt@redhat.com>2014-11-26 16:07:50 +0000
committerMike Snitzer <snitzer@redhat.com>2014-12-01 11:30:11 -0500
commit2bb812df63bbd246bd39d10f2e810b2a0a59e99e (patch)
tree071abce53825307314e1531fb81a3b58619600af /drivers/md
parent43c32bf2b0c16d292f4f214dfd16f9cb205e4e81 (diff)
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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: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-cache-target.c9
1 files 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))
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