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>

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 41569bc60abc9dfe2d8986beba23099ffd068d31..c64fe827a5f19abc60c2040b0690ca9b5003598c 100644 (file)
--- 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 +