From: Joe Thornber Date: Fri, 28 Nov 2014 09:48:25 +0000 (+0000) Subject: dm cache: fix spurious cell_defer when dealing with partial block at end of device X-Git-Tag: v3.17.8~51 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f5e3cd8f7b12622d6e84b68ff1fa8814987f99fb;p=thirdparty%2Fkernel%2Fstable.git dm cache: fix spurious cell_defer when dealing with partial block at end of device commit f824a2af3dfbbb766c02e19df21f985bceadf0ee upstream. 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 387b93d81138d..da496cfb458d7 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); }