From: Joe Thornber Date: Fri, 28 Nov 2014 09:48:25 +0000 Subject: [PATCH] dm cache: fix spurious cell_defer when dealing with partial block at end of device We never bother caching a partial block that is at the back end of the origin device. No cell ever gets locked, but the calling code was assuming it was and trying to release it. Now the code only releases if the cell has been set to a non NULL value. Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org --- drivers/md/dm-cache-target.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 387b93d81138..da496cfb458d 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2554,11 +2554,11 @@ static int __cache_map(struct cache *cache, struct bio *bio, struct dm_bio_priso static int cache_map(struct dm_target *ti, struct bio *bio) { int r; - struct dm_bio_prison_cell *cell; + struct dm_bio_prison_cell *cell = NULL; struct cache *cache = ti->private; r = __cache_map(cache, bio, &cell); - if (r == DM_MAPIO_REMAPPED) { + if (r == DM_MAPIO_REMAPPED && cell) { inc_ds(cache, bio, cell); cell_defer(cache, cell, false); } -- 2.1.0