[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>

1 files changed, 3 insertions, 0 deletions

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