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Commit 494b3ee7 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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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: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 8627921f

drivers/md/dm-snap.c

+11 −0
Original line number Diff line number Diff line
@@ -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;

}