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 <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Joe Thornber 2014-11-28 09:48:25 +00:00 committed by Mike Snitzer
parent 1e32134a5a
commit f824a2af3d

View file

@ -2690,11 +2690,11 @@ 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);
}