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Commit a2aebe03 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
Browse files

dm raid1: use timer 



This patch replaces the schedule() in the main kmirrord thread with a timer.
The schedule() could introduce an unwanted delay when work is ready to be
processed.

The code instead calls wake() when there's work to be done immediately, and
delayed_wake() after a failure to give a short delay before retrying.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent a765e20e

drivers/md/dm-raid1.c

+28 −20
Original line number Diff line number Diff line
@@ -154,6 +154,9 @@ struct mirror_set { 


	struct workqueue_struct *kmirrord_wq;

	struct work_struct kmirrord_work;

	struct timer_list timer;

	unsigned long timer_pending;



	struct work_struct trigger_event;



	unsigned int nr_mirrors;
@@ -178,6 +181,25 @@ static void wake(struct mirror_set *ms) 
	queue_work(ms->kmirrord_wq, &ms->kmirrord_work);

}



static void delayed_wake_fn(unsigned long data)

{

	struct mirror_set *ms = (struct mirror_set *) data;



	clear_bit(0, &ms->timer_pending);

	wake(ms);

}



static void delayed_wake(struct mirror_set *ms)

{

	if (test_and_set_bit(0, &ms->timer_pending))

		return;



	ms->timer.expires = jiffies + HZ / 5;

	ms->timer.data = (unsigned long) ms;

	ms->timer.function = delayed_wake_fn;

	add_timer(&ms->timer);

}



/* FIXME move this */

static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
@@ -1180,6 +1202,7 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes) 
		spin_lock_irq(&ms->lock);

		bio_list_merge(&ms->failures, &sync);

		spin_unlock_irq(&ms->lock);

		wake(ms);

	} else

		while ((bio = bio_list_pop(&sync)))

			do_write(ms, bio);
@@ -1239,7 +1262,7 @@ static void do_failures(struct mirror_set *ms, struct bio_list *failures) 
	bio_list_merge(&ms->failures, failures);

	spin_unlock_irq(&ms->lock);



	wake(ms);

	delayed_wake(ms);

}



static void trigger_event(struct work_struct *work)
@@ -1253,7 +1276,7 @@ static void trigger_event(struct work_struct *work) 
/*-----------------------------------------------------------------

 * kmirrord

 *---------------------------------------------------------------*/

static int _do_mirror(struct work_struct *work)

static void do_mirror(struct work_struct *work)

{

	struct mirror_set *ms =container_of(work, struct mirror_set,

					    kmirrord_work);
@@ -1274,24 +1297,6 @@ static int _do_mirror(struct work_struct *work) 
	do_reads(ms, &reads);

	do_writes(ms, &writes);

	do_failures(ms, &failures);



	return (ms->failures.head) ? 1 : 0;

}



static void do_mirror(struct work_struct *work)

{

	/*

	 * If _do_mirror returns 1, we give it

	 * another shot.  This helps for cases like

	 * 'suspend' where we call flush_workqueue

	 * and expect all work to be finished.  If

	 * a failure happens during a suspend, we

	 * couldn't issue a 'wake' because it would

	 * not be honored.  Therefore, we return '1'

	 * from _do_mirror, and retry here.

	 */

	while (_do_mirror(work))

		schedule();

}
@@ -1545,6 +1550,8 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv) 
		goto err_free_context;

	}

	INIT_WORK(&ms->kmirrord_work, do_mirror);

	init_timer(&ms->timer);

	ms->timer_pending = 0;

	INIT_WORK(&ms->trigger_event, trigger_event);



	r = parse_features(ms, argc, argv, &args_used);
@@ -1587,6 +1594,7 @@ static void mirror_dtr(struct dm_target *ti) 
{

	struct mirror_set *ms = (struct mirror_set *) ti->private;



	del_timer_sync(&ms->timer);

	flush_workqueue(ms->kmirrord_wq);

	dm_kcopyd_client_destroy(ms->kcopyd_client);

	destroy_workqueue(ms->kmirrord_wq);