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dm snapshot: support barriers

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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>
This commit is contained in:
Mikulas Patocka 2009-06-22 10:12:25 +01:00 committed by Alasdair G Kergon
parent 8627921fa2
commit 494b3ee7d4
1 changed files with 11 additions and 0 deletions
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11
drivers/md/dm-snap.c
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@ -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;
}