dm delay: support barriers

Flush support for dm-delay target.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
index 559dbb52bc85..8ad8a9044bbf 100644
--- a/drivers/md/dm-delay.c
+++ b/drivers/md/dm-delay.c
@@ -197,6 +197,7 @@ out:
         mutex_init(&dc->timer_lock);
         atomic_set(&dc->may_delay, 1);
 
+        ti->num_flush_requests = 1;
         ti->private = dc;
         return 0;
 
@@ -278,8 +279,9 @@ static int delay_map(struct dm_target *ti, struct bio *bio,
 
         if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
                 bio->bi_bdev = dc->dev_write->bdev;
-                bio->bi_sector = dc->start_write +
-                                 (bio->bi_sector - ti->begin);
+                if (bio_sectors(bio))
+                        bio->bi_sector = dc->start_write +
+                                         (bio->bi_sector - ti->begin);
 
                 return delay_bio(dc, dc->write_delay, bio);
         }