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Commit 0d129228 authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
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[PATCH] md: define ->congested_fn for raid1, raid10, and multipath 



raid1, raid10 and multipath don't report their 'congested' status through
bdi_*_congested, but should.

This patch adds the appropriate functions which just check the 'congested'
status of all active members (with appropriate locking).

raid1 read_balance should be modified to prefer devices where
bdi_read_congested returns false.  Then we could use the '&' branch rather
than the '|' branch.  However that should would need some benchmarking first
to make sure it is actually a good idea.

Signed-off-by: default avatarNeil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 26be34dc

drivers/md/multipath.c

+24 −0
Original line number Diff line number Diff line
@@ -228,6 +228,28 @@ static int multipath_issue_flush(request_queue_t *q, struct gendisk *disk, 
	rcu_read_unlock();

	return ret;

}

static int multipath_congested(void *data, int bits)

{

	mddev_t *mddev = data;

	multipath_conf_t *conf = mddev_to_conf(mddev);

	int i, ret = 0;



	rcu_read_lock();

	for (i = 0; i < mddev->raid_disks ; i++) {

		mdk_rdev_t *rdev = rcu_dereference(conf->multipaths[i].rdev);

		if (rdev && !test_bit(Faulty, &rdev->flags)) {

			request_queue_t *q = bdev_get_queue(rdev->bdev);



			ret |= bdi_congested(&q->backing_dev_info, bits);

			/* Just like multipath_map, we just check the

			 * first available device

			 */

			break;

		}

	}

	rcu_read_unlock();

	return ret;

}



/*

 * Careful, this can execute in IRQ contexts as well!
@@ -509,6 +531,8 @@ static int multipath_run (mddev_t *mddev) 


	mddev->queue->unplug_fn = multipath_unplug;

	mddev->queue->issue_flush_fn = multipath_issue_flush;

	mddev->queue->backing_dev_info.congested_fn = multipath_congested;

	mddev->queue->backing_dev_info.congested_data = mddev;



	return 0;

drivers/md/raid1.c

+28 −0
Original line number Diff line number Diff line
@@ -601,6 +601,32 @@ static int raid1_issue_flush(request_queue_t *q, struct gendisk *disk, 
	return ret;

}



static int raid1_congested(void *data, int bits)

{

	mddev_t *mddev = data;

	conf_t *conf = mddev_to_conf(mddev);

	int i, ret = 0;



	rcu_read_lock();

	for (i = 0; i < mddev->raid_disks; i++) {

		mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);

		if (rdev && !test_bit(Faulty, &rdev->flags)) {

			request_queue_t *q = bdev_get_queue(rdev->bdev);



			/* Note the '|| 1' - when read_balance prefers

			 * non-congested targets, it can be removed

			 */

			if ((bits & (1<<BDI_write_congested)) || 1)

				ret |= bdi_congested(&q->backing_dev_info, bits);

			else

				ret &= bdi_congested(&q->backing_dev_info, bits);

		}

	}

	rcu_read_unlock();

	return ret;

}





/* Barriers....

 * Sometimes we need to suspend IO while we do something else,

 * either some resync/recovery, or reconfigure the array.
@@ -1965,6 +1991,8 @@ static int run(mddev_t *mddev) 


	mddev->queue->unplug_fn = raid1_unplug;

	mddev->queue->issue_flush_fn = raid1_issue_flush;

	mddev->queue->backing_dev_info.congested_fn = raid1_congested;

	mddev->queue->backing_dev_info.congested_data = mddev;



	return 0;

drivers/md/raid10.c

+22 −0
Original line number Diff line number Diff line
@@ -648,6 +648,26 @@ static int raid10_issue_flush(request_queue_t *q, struct gendisk *disk, 
	return ret;

}



static int raid10_congested(void *data, int bits)

{

	mddev_t *mddev = data;

	conf_t *conf = mddev_to_conf(mddev);

	int i, ret = 0;



	rcu_read_lock();

	for (i = 0; i < mddev->raid_disks && ret == 0; i++) {

		mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev);

		if (rdev && !test_bit(Faulty, &rdev->flags)) {

			request_queue_t *q = bdev_get_queue(rdev->bdev);



			ret |= bdi_congested(&q->backing_dev_info, bits);

		}

	}

	rcu_read_unlock();

	return ret;

}





/* Barriers....

 * Sometimes we need to suspend IO while we do something else,

 * either some resync/recovery, or reconfigure the array.
@@ -2094,6 +2114,8 @@ static int run(mddev_t *mddev) 


	mddev->queue->unplug_fn = raid10_unplug;

	mddev->queue->issue_flush_fn = raid10_issue_flush;

	mddev->queue->backing_dev_info.congested_fn = raid10_congested;

	mddev->queue->backing_dev_info.congested_data = mddev;



	/* Calculate max read-ahead size.

	 * We need to readahead at least twice a whole stripe....