dm thin: fix inability to discard blocks when in out-of-data-space mode

commit 45ec9bd0fd7abf8705e7cf12205ff69fe9d51181 upstream.

When the pool was in PM_OUT_OF_SPACE mode its process_prepared_discard
function pointer was incorrectly being set to
process_prepared_discard_passdown rather than process_prepared_discard.

This incorrect function pointer meant the discard was being passed down,
but not effecting the mapping.  As such any discard that was issued, in
an attempt to reclaim blocks, would not successfully free data space.

Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 6f75083a81cc0057713f8e1dd0d408a195246a55..c13efb1020d98c7d6a8335adc33e81c273999243 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1759,7 +1759,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
                pool->process_bio = process_bio_read_only;
                pool->process_discard = process_discard;
                pool->process_prepared_mapping = process_prepared_mapping;
-               pool->process_prepared_discard = process_prepared_discard_passdown;
+               pool->process_prepared_discard = process_prepared_discard;
 
                if (!pool->pf.error_if_no_space && no_space_timeout)
                        queue_delayed_work(pool->wq, &pool->no_space_timeout, no_space_timeout);