From 233886dd32ad71daf9c21bf3728c0933a94870f0 Mon Sep 17 00:00:00 2001
From: "jblunck@suse.de" <jblunck@suse.de>
Date: Mon, 21 Nov 2005 21:32:36 -0800
Subject: [PATCH] [PATCH] device-mapper snapshot: bio_list fix

bio_list_merge() should do nothing if the second list is empty - not oops.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 drivers/md/dm-bio-list.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/md/dm-bio-list.h b/drivers/md/dm-bio-list.h
index bc021e1fd4d1..bbf4615f0e30 100644
--- a/drivers/md/dm-bio-list.h
+++ b/drivers/md/dm-bio-list.h
@@ -33,6 +33,9 @@ static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
 
 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 {
+	if (!bl2->head)
+		return;
+
 	if (bl->tail)
 		bl->tail->bi_next = bl2->head;
 	else