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Commit 6f757231 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Jens Axboe
Browse files

dm: remove the pending IO accounting 



Remove the "pending" atomic counters, that duplicate block-core's
in_flight counters, and update md_in_flight() to look at percpu
in_flight counters.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e016b782

drivers/md/dm-core.h

+0 −2
Original line number Diff line number Diff line
@@ -65,7 +65,6 @@ struct mapped_device { 
	 */

	struct work_struct work;

	wait_queue_head_t wait;

	atomic_t pending[2];

	spinlock_t deferred_lock;

	struct bio_list deferred;
@@ -119,7 +118,6 @@ struct mapped_device { 
	struct srcu_struct io_barrier;

};



int md_in_flight(struct mapped_device *md);

void disable_write_same(struct mapped_device *md);

void disable_write_zeroes(struct mapped_device *md);

drivers/md/dm.c

+15 −19
Original line number Diff line number Diff line
@@ -646,25 +646,30 @@ static void free_tio(struct dm_target_io *tio) 
	bio_put(&tio->clone);

}



int md_in_flight(struct mapped_device *md)

static bool md_in_flight(struct mapped_device *md)

{

	return atomic_read(&md->pending[READ]) +

	       atomic_read(&md->pending[WRITE]);

	int cpu;

	struct hd_struct *part = &dm_disk(md)->part0;



	for_each_possible_cpu(cpu) {

		if (part_stat_local_read_cpu(part, in_flight[0], cpu) ||

		    part_stat_local_read_cpu(part, in_flight[1], cpu))

			return true;

	}



	return false;

}



static void start_io_acct(struct dm_io *io)

{

	struct mapped_device *md = io->md;

	struct bio *bio = io->orig_bio;

	int rw = bio_data_dir(bio);



	io->start_time = jiffies;



	generic_start_io_acct(md->queue, bio_op(bio), bio_sectors(bio),

			      &dm_disk(md)->part0);



	atomic_inc(&md->pending[rw]);



	if (unlikely(dm_stats_used(&md->stats)))

		dm_stats_account_io(&md->stats, bio_data_dir(bio),

				    bio->bi_iter.bi_sector, bio_sectors(bio),
@@ -676,8 +681,6 @@ static void end_io_acct(struct dm_io *io) 
	struct mapped_device *md = io->md;

	struct bio *bio = io->orig_bio;

	unsigned long duration = jiffies - io->start_time;

	int pending;

	int rw = bio_data_dir(bio);



	generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0,

			    io->start_time);
@@ -687,17 +690,12 @@ static void end_io_acct(struct dm_io *io) 
				    bio->bi_iter.bi_sector, bio_sectors(bio),

				    true, duration, &io->stats_aux);



	/*

	 * After this is decremented the bio must not be touched if it is

	 * a flush.

	 */

	pending = atomic_dec_return(&md->pending[rw]);

	pending += atomic_read(&md->pending[rw^0x1]);



	/* nudge anyone waiting on suspend queue */

	if (!pending)

	if (unlikely(waitqueue_active(&md->wait))) {

		if (!md_in_flight(md))

			wake_up(&md->wait);

	}

}



/*

 * Add the bio to the list of deferred io.
@@ -1915,8 +1913,6 @@ static struct mapped_device *alloc_dev(int minor) 
	if (!md->disk)

		goto bad;



	atomic_set(&md->pending[0], 0);

	atomic_set(&md->pending[1], 0);

	init_waitqueue_head(&md->wait);

	INIT_WORK(&md->work, dm_wq_work);

	init_waitqueue_head(&md->eventq);