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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 0f86d802b533301bf8374eb07cd9224dd06c799c..630398e1bf09319113be4f602c480d73f9b8ef4b 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1824,7 +1824,7 @@ 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);