[PATCH 4.9 054/153] dm cache: fix corruption seen when using cache > 2TB

Greg Kroah-Hartman
2017-03-10T09:19:42Z

From: Joe Thornber <ejt@redhat.com>

commit ca763d0a53b264a650342cee206512bc92ac7050 upstream.

A rounding bug due to compiler generated temporary being 32bit was found
in remap_to_cache(). A localized cast in remap_to_cache() fixes the
corruption but this preferred fix (changing from uint32_t to sector_t)
eliminates potential for future rounding errors elsewhere.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-cache-target.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -248,7 +248,7 @@ struct cache {
/*
* Fields for converting from sectors to blocks.
*/
- uint32_t sectors_per_block;
+ sector_t sectors_per_block;
int sectors_per_block_shift;

spinlock_t lock;
@@ -3546,11 +3546,11 @@ static void cache_status(struct dm_targe

residency = policy_residency(cache->policy);

- DMEMIT("%u %llu/%llu %u %llu/%llu %u %u %u %u %u %u %lu ",
+ DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
(unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
(unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
(unsigned long long)nr_blocks_metadata,
- cache->sectors_per_block,
+ (unsigned long long)cache->sectors_per_block,
(unsigned long long) from_cblock(residency),
(unsigned long long) from_cblock(cache->cache_size),
(unsigned) atomic_read(&cache->stats.read_hit),