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authorMikulas Patocka <mpatocka@redhat.com>2009-06-22 10:12:25 +0100
committerAlasdair G Kergon <agk@redhat.com>2009-06-22 10:12:25 +0100
commit494b3ee7d4f69210def80aecce28d08c3f0755d5 (patch)
tree8cd8fc4de72cf9a1a56e45518019a3cae106515a /drivers/md
parent8627921fa2ef6d40fd9b787e163ba3a9ff8f471d (diff)
dm snapshot: support barriers
Flush support for dm-snapshot target. This patch just forwards the flush request to either the origin or the snapshot device. (It doesn't flush exception store metadata.) Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-snap.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index d73f17fc7778..d573165cd2b7 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -678,6 +678,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
ti->private = s;
ti->split_io = s->store->chunk_size;
+ ti->num_flush_requests = 1;
return 0;
@@ -1030,6 +1031,11 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
chunk_t chunk;
struct dm_snap_pending_exception *pe = NULL;
+ if (unlikely(bio_empty_barrier(bio))) {
+ bio->bi_bdev = s->store->cow->bdev;
+ return DM_MAPIO_REMAPPED;
+ }
+
chunk = sector_to_chunk(s->store, bio->bi_sector);
/* Full snapshots are not usable */
@@ -1338,6 +1344,8 @@ static int origin_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
ti->private = dev;
+ ti->num_flush_requests = 1;
+
return 0;
}
@@ -1353,6 +1361,9 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
struct dm_dev *dev = ti->private;
bio->bi_bdev = dev->bdev;
+ if (unlikely(bio_empty_barrier(bio)))
+ return DM_MAPIO_REMAPPED;
+
/* Only tell snapshots if this is a write */
return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
}