dm persistent data: fix shadow_info_leak on dm_tm_destroy

commit 25d7cd6faa7ae6ed2565617c3ee2500ccb8a9f7f upstream.

Cleanup the shadow table before destroying the transaction manager.

Reference: leak was identified with kmemleak when running
test_discard_random_sectors in the thinp-test-suite.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index 6f8d387..e5902d1 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -138,6 +138,9 @@
 
 void dm_tm_destroy(struct dm_transaction_manager *tm)
 {
+	if (!tm->is_clone)
+		wipe_shadow_table(tm);
+
 	kfree(tm);
 }
 EXPORT_SYMBOL_GPL(dm_tm_destroy);