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dm cache: fix truncation bug when mapping I/O to >2TB fast device

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When remapping a block to the cache's fast device that is larger than
2TB we must not truncate the destination sector to 32bits.  The 32bit
temporary result of from_cblock() was being overflowed in
remap_to_cache() due to the logical left shift.

Use an intermediate 64bit type to store the 32bit from_cblock() result
to fix the overflow.

Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Heinz Mauelshagen 2014-02-27 22:46:48 +01:00 committed by Mike Snitzer
parent 7d48935eff
commit e0d849fad7
1 changed files with 3 additions and 2 deletions
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5
drivers/md/dm-cache-target.c
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@ -671,15 +671,16 @@ static void remap_to_cache(struct cache *cache, struct bio *bio,
dm_cblock_t cblock)
{
sector_t bi_sector = bio->bi_iter.bi_sector;
sector_t block = from_cblock(cblock);
bio->bi_bdev = cache->cache_dev->bdev;
if (!block_size_is_power_of_two(cache))
bio->bi_iter.bi_sector =
(from_cblock(cblock) * cache->sectors_per_block) +
(block * cache->sectors_per_block) +
sector_div(bi_sector, cache->sectors_per_block);
else
bio->bi_iter.bi_sector =
(from_cblock(cblock) << cache->sectors_per_block_shift) |
(block << cache->sectors_per_block_shift) |
(bi_sector & (cache->sectors_per_block - 1));
}