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Commit a79245b3 authored by Mike Snitzer's avatar Mike Snitzer Committed by Alasdair G Kergon
Browse files

dm: split discard requests on target boundaries 



Update __clone_and_map_discard to loop across all targets in a DM
device's table when it processes a discard bio.  If a discard crosses a
target boundary it must be split accordingly.

Update __issue_target_requests and __issue_target_request to allow a
cloned discard bio to have a custom start sector and size.

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent c96053b7

drivers/md/dm.c

+23 −24
Original line number Diff line number Diff line
@@ -1193,7 +1193,7 @@ static struct dm_target_io *alloc_tio(struct clone_info *ci, 
}



static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,

				   unsigned request_nr)

				   unsigned request_nr, sector_t len)

{

	struct dm_target_io *tio = alloc_tio(ci, ti);

	struct bio *clone;
@@ -1208,17 +1208,21 @@ static void __issue_target_request(struct clone_info *ci, struct dm_target *ti, 
	clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs);

	__bio_clone(clone, ci->bio);

	clone->bi_destructor = dm_bio_destructor;

	if (len) {

		clone->bi_sector = ci->sector;

		clone->bi_size = to_bytes(len);

	}



	__map_bio(ti, clone, tio);

}



static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,

				    unsigned num_requests)

				    unsigned num_requests, sector_t len)

{

	unsigned request_nr;



	for (request_nr = 0; request_nr < num_requests; request_nr++)

		__issue_target_request(ci, ti, request_nr);

		__issue_target_request(ci, ti, request_nr, len);

}



static int __clone_and_map_empty_barrier(struct clone_info *ci)
@@ -1227,7 +1231,7 @@ static int __clone_and_map_empty_barrier(struct clone_info *ci) 
	struct dm_target *ti;



	while ((ti = dm_table_get_target(ci->map, target_nr++)))

		__issue_target_requests(ci, ti, ti->num_flush_requests);

		__issue_target_requests(ci, ti, ti->num_flush_requests, 0);



	ci->sector_count = 0;
@@ -1253,8 +1257,9 @@ static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti) 
static int __clone_and_map_discard(struct clone_info *ci)

{

	struct dm_target *ti;

	sector_t max;

	sector_t len;



	do {

		ti = dm_table_find_target(ci->map, ci->sector);

		if (!dm_target_is_valid(ti))

			return -EIO;
@@ -1264,21 +1269,15 @@ static int __clone_and_map_discard(struct clone_info *ci) 
		 * reconfiguration might have changed that since the

		 * check was performed.

		 */



		if (!ti->num_discard_requests)

			return -EOPNOTSUPP;



	max = max_io_len(ci->sector, ti);

		len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));



	if (ci->sector_count > max)

		/*

		 * FIXME: Handle a discard that spans two or more targets.

		 */

		return -EOPNOTSUPP;



	__issue_target_requests(ci, ti, ti->num_discard_requests);

		__issue_target_requests(ci, ti, ti->num_discard_requests, len);



	ci->sector_count = 0;

		ci->sector += len;

	} while (ci->sector_count -= len);



	return 0;

}