dm crypt: support flush

Flush support for dm-crypt target.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 53394e863c74..04db6c4004a8 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1132,6 +1132,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto bad_crypt_queue;
         }
 
+        ti->num_flush_requests = 1;
         ti->private = cc;
         return 0;
 
@@ -1189,6 +1190,13 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
                      union map_info *map_context)
 {
         struct dm_crypt_io *io;
+        struct crypt_config *cc;
+
+        if (unlikely(bio_empty_barrier(bio))) {
+                cc = ti->private;
+                bio->bi_bdev = cc->dev->bdev;
+                return DM_MAPIO_REMAPPED;
+        }
 
         io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin);