dm: stripe support flush

Flush support for the stripe target.

This sets ti->num_flush_requests to the number of stripes and
remaps individual flush requests to the appropriate stripe devices.

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

1 files changed, 12 insertions, 3 deletions

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 41569bc60abc..c64fe827a5f1 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -167,6 +167,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         sc->stripes = stripes;
         sc->stripe_width = width;
         ti->split_io = chunk_size;
+        ti->num_flush_requests = stripes;
 
         sc->chunk_mask = ((sector_t) chunk_size) - 1;
         for (sc->chunk_shift = 0; chunk_size; sc->chunk_shift++)
@@ -211,10 +212,18 @@ static int stripe_map(struct dm_target *ti, struct bio *bio,
                       union map_info *map_context)
 {
         struct stripe_c *sc = (struct stripe_c *) ti->private;
+        sector_t offset, chunk;
+        uint32_t stripe;
 
-        sector_t offset = bio->bi_sector - ti->begin;
-        sector_t chunk = offset >> sc->chunk_shift;
-        uint32_t stripe = sector_div(chunk, sc->stripes);
+        if (unlikely(bio_empty_barrier(bio))) {
+                BUG_ON(map_context->flush_request >= sc->stripes);
+                bio->bi_bdev = sc->stripe[map_context->flush_request].dev->bdev;
+                return DM_MAPIO_REMAPPED;
+        }
+
+        offset = bio->bi_sector - ti->begin;
+        chunk = offset >> sc->chunk_shift;
+        stripe = sector_div(chunk, sc->stripes);
 
         bio->bi_bdev = sc->stripe[stripe].dev->bdev;
         bio->bi_sector = sc->stripe[stripe].physical_start +