dm raid1: support flush

Flush support for dm-raid1.

When it receives an empty barrier, submit it to all the devices via dm-io.

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

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index cc9dc79b0784..752a29e1855b 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -396,6 +396,8 @@ static int mirror_available(struct mirror_set *ms, struct bio *bio)
  */
 static sector_t map_sector(struct mirror *m, struct bio *bio)
 {
+        if (unlikely(!bio->bi_size))
+                return 0;
         return m->offset + (bio->bi_sector - m->ms->ti->begin);
 }
 
@@ -562,7 +564,7 @@ static void do_write(struct mirror_set *ms, struct bio *bio)
         struct dm_io_region io[ms->nr_mirrors], *dest = io;
         struct mirror *m;
         struct dm_io_request io_req = {
-                .bi_rw = WRITE,
+                .bi_rw = WRITE | (bio->bi_rw & WRITE_BARRIER),
                 .mem.type = DM_IO_BVEC,
                 .mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
                 .notify.fn = write_callback,
@@ -603,6 +605,11 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
         bio_list_init(&requeue);
 
         while ((bio = bio_list_pop(writes))) {
+                if (unlikely(bio_empty_barrier(bio))) {
+                        bio_list_add(&sync, bio);
+                        continue;
+                }
+
                 region = dm_rh_bio_to_region(ms->rh, bio);
 
                 if (log->type->is_remote_recovering &&
@@ -995,6 +1002,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
         ti->private = ms;
         ti->split_io = dm_rh_get_region_size(ms->rh);
+        ti->num_flush_requests = 1;
 
         ms->kmirrord_wq = create_singlethread_workqueue("kmirrord");
         if (!ms->kmirrord_wq) {
@@ -1122,7 +1130,8 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio,
          * We need to dec pending if this was a write.
          */
         if (rw == WRITE) {
-                dm_rh_dec(ms->rh, map_context->ll);
+                if (likely(!bio_empty_barrier(bio)))
+                        dm_rh_dec(ms->rh, map_context->ll);
                 return error;
         }