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Commit c91852ff authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: optimize dm_request_fn() 



DM multipath is the only request-based DM target -- which only supports
tables with a single target that is immutable.  Leverage this fact in
dm_request_fn().

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 16f12266

drivers/md/dm.c

+17 −30
Original line number Diff line number Diff line
@@ -2071,12 +2071,18 @@ static bool dm_request_peeked_before_merge_deadline(struct mapped_device *md) 
static void dm_request_fn(struct request_queue *q)

{

	struct mapped_device *md = q->queuedata;

	int srcu_idx;

	struct dm_table *map = dm_get_live_table(md, &srcu_idx);

	struct dm_target *ti;

	struct dm_target *ti = md->immutable_target;

	struct request *rq;

	struct dm_rq_target_io *tio;

	sector_t pos;

	sector_t pos = 0;



	if (unlikely(!ti)) {

		int srcu_idx;

		struct dm_table *map = dm_get_live_table(md, &srcu_idx);



		ti = dm_table_find_target(map, pos);

		dm_put_live_table(md, srcu_idx);

	}



	/*

	 * For suspend, check blk_queue_stopped() and increment
@@ -2087,32 +2093,20 @@ static void dm_request_fn(struct request_queue *q) 
	while (!blk_queue_stopped(q)) {

		rq = blk_peek_request(q);

		if (!rq)

			goto out;

			return;



		/* always use block 0 to find the target for flushes for now */

		pos = 0;

		if (!(rq->cmd_flags & REQ_FLUSH))

			pos = blk_rq_pos(rq);



		ti = dm_table_find_target(map, pos);

		if (!dm_target_is_valid(ti)) {

			/*

			 * Must perform setup, that rq_completed() requires,

			 * before calling dm_kill_unmapped_request

			 */

			DMERR_LIMIT("request attempted access beyond the end of device");

			dm_start_request(md, rq);

			dm_kill_unmapped_request(rq, -EIO);

			continue;

		}



		if (dm_request_peeked_before_merge_deadline(md) &&

		if ((dm_request_peeked_before_merge_deadline(md) &&

		     md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&

		    md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq))

			goto delay_and_out;



		if (ti->type->busy && ti->type->busy(ti))

			goto delay_and_out;

		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||

		    (ti->type->busy && ti->type->busy(ti))) {

			blk_delay_queue(q, HZ / 100);

			return;

		}



		dm_start_request(md, rq);
@@ -2122,13 +2116,6 @@ static void dm_request_fn(struct request_queue *q) 
		queue_kthread_work(&md->kworker, &tio->work);

		BUG_ON(!irqs_disabled());

	}



	goto out;



delay_and_out:

	blk_delay_queue(q, HZ / 100);

out:

	dm_put_live_table(md, srcu_idx);

}



static int dm_any_congested(void *congested_data, int bdi_bits)