jbd2 commit: fix transaction dropping

We have to check that also the second checkpoint list is non-empty before
dropping the transaction.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Chuck Ebbert <cebbert@redhat.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: <linux-ext4@vger.kernel.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/jbd2/commit.c

@@ -896,7 +896,8 @@ restart_loop:
 	journal->j_committing_transaction = NULL;
 	spin_unlock(&journal->j_state_lock);
 
-	if (commit_transaction->t_checkpoint_list == NULL) {
+	if (commit_transaction->t_checkpoint_list == NULL &&
+	    commit_transaction->t_checkpoint_io_list == NULL) {
 		__jbd2_journal_drop_transaction(journal, commit_transaction);
 	} else {
 		if (journal->j_checkpoint_transactions == NULL) {