dm: bio list add bio_list_add_head

Introduce a function that adds a bio to the head of the list for
use by the patch that will support barriers.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/md/dm-bio-list.h b/drivers/md/dm-bio-list.h
index d4509be0fe67..345098b4ca77 100644
--- a/drivers/md/dm-bio-list.h
+++ b/drivers/md/dm-bio-list.h
@@ -52,6 +52,16 @@ static inline void bio_list_add(struct bio_list *bl, struct bio *bio)
         bl->tail = bio;
 }
 
+static inline void bio_list_add_head(struct bio_list *bl, struct bio *bio)
+{
+        bio->bi_next = bl->head;
+
+        bl->head = bio;
+
+        if (!bl->tail)
+                bl->tail = bio;
+}
+
 static inline void bio_list_merge(struct bio_list *bl, struct bio_list *bl2)
 {
         if (!bl2->head)