Commit 77216b04 authored by Tejun Heo's avatar Tejun Heo
Browse files

blk-throttle: add throtl_service_queue->parent_sq 



To prepare for hierarchy support, this patch adds
throtl_service_queue->service_sq which points to the arent
service_queue.  Currently, for all service_queues embedded in
throtl_grps, it points to throtl_data->service_queue.  As
throtl_data->service_queue doesn't have a parent its parent_sq is set
to NULL.

There are a number of functions which take both throtl_grp *tg and
throtl_service_queue *parent_sq.  With this patch, the parent
service_queue can be determined from @tg and the @parent_sq arguments
are removed.

This patch doesn't make any behavior differences.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
parent 0e9f4164

block/blk-throttle.c

+39 −42
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ static struct blkcg_policy blkcg_policy_throtl; 
static struct workqueue_struct *kthrotld_workqueue;



struct throtl_service_queue {

	struct throtl_service_queue *parent_sq;	/* the parent service_queue */



	/*

	 * Bios queued directly to this service_queue or dispatched from

	 * children throtl_grp's.
@@ -197,21 +199,24 @@ alloc_stats: 
}



/* init a service_queue, assumes the caller zeroed it */

static void throtl_service_queue_init(struct throtl_service_queue *sq)

static void throtl_service_queue_init(struct throtl_service_queue *sq,

				      struct throtl_service_queue *parent_sq)

{

	bio_list_init(&sq->bio_lists[0]);

	bio_list_init(&sq->bio_lists[1]);

	sq->pending_tree = RB_ROOT;

	sq->parent_sq = parent_sq;

}



static void throtl_pd_init(struct blkcg_gq *blkg)

{

	struct throtl_grp *tg = blkg_to_tg(blkg);

	struct throtl_data *td = blkg->q->td;

	unsigned long flags;



	throtl_service_queue_init(&tg->service_queue);

	throtl_service_queue_init(&tg->service_queue, &td->service_queue);

	RB_CLEAR_NODE(&tg->rb_node);

	tg->td = blkg->q->td;

	tg->td = td;



	tg->bps[READ] = -1;

	tg->bps[WRITE] = -1;
@@ -339,9 +344,9 @@ static void update_min_dispatch_time(struct throtl_service_queue *parent_sq) 
	parent_sq->first_pending_disptime = tg->disptime;

}



static void tg_service_queue_add(struct throtl_grp *tg,

				 struct throtl_service_queue *parent_sq)

static void tg_service_queue_add(struct throtl_grp *tg)

{

	struct throtl_service_queue *parent_sq = tg->service_queue.parent_sq;

	struct rb_node **node = &parent_sq->pending_tree.rb_node;

	struct rb_node *parent = NULL;

	struct throtl_grp *__tg;
@@ -367,33 +372,29 @@ static void tg_service_queue_add(struct throtl_grp *tg, 
	rb_insert_color(&tg->rb_node, &parent_sq->pending_tree);

}



static void __throtl_enqueue_tg(struct throtl_grp *tg,

				struct throtl_service_queue *parent_sq)

static void __throtl_enqueue_tg(struct throtl_grp *tg)

{

	tg_service_queue_add(tg, parent_sq);

	tg_service_queue_add(tg);

	tg->flags |= THROTL_TG_PENDING;

	parent_sq->nr_pending++;

	tg->service_queue.parent_sq->nr_pending++;

}



static void throtl_enqueue_tg(struct throtl_grp *tg,

			      struct throtl_service_queue *parent_sq)

static void throtl_enqueue_tg(struct throtl_grp *tg)

{

	if (!(tg->flags & THROTL_TG_PENDING))

		__throtl_enqueue_tg(tg, parent_sq);

		__throtl_enqueue_tg(tg);

}



static void __throtl_dequeue_tg(struct throtl_grp *tg,

				struct throtl_service_queue *parent_sq)

static void __throtl_dequeue_tg(struct throtl_grp *tg)

{

	throtl_rb_erase(&tg->rb_node, parent_sq);

	throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);

	tg->flags &= ~THROTL_TG_PENDING;

}



static void throtl_dequeue_tg(struct throtl_grp *tg,

			      struct throtl_service_queue *parent_sq)

static void throtl_dequeue_tg(struct throtl_grp *tg)

{

	if (tg->flags & THROTL_TG_PENDING)

		__throtl_dequeue_tg(tg, parent_sq);

		__throtl_dequeue_tg(tg);

}



/* Call with queue lock held */
@@ -707,8 +708,7 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio) 
	throtl_update_dispatch_stats(tg_to_blkg(tg), bio->bi_size, bio->bi_rw);

}



static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg,

			      struct throtl_service_queue *parent_sq)

static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg)

{

	struct throtl_service_queue *sq = &tg->service_queue;

	bool rw = bio_data_dir(bio);
@@ -727,11 +727,10 @@ static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg, 
	blkg_get(tg_to_blkg(tg));

	sq->nr_queued[rw]++;

	tg->td->nr_queued[rw]++;

	throtl_enqueue_tg(tg, parent_sq);

	throtl_enqueue_tg(tg);

}



static void tg_update_disptime(struct throtl_grp *tg,

			       struct throtl_service_queue *parent_sq)

static void tg_update_disptime(struct throtl_grp *tg)

{

	struct throtl_service_queue *sq = &tg->service_queue;

	unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
@@ -747,16 +746,15 @@ static void tg_update_disptime(struct throtl_grp *tg, 
	disptime = jiffies + min_wait;



	/* Update dispatch time */

	throtl_dequeue_tg(tg, parent_sq);

	throtl_dequeue_tg(tg);

	tg->disptime = disptime;

	throtl_enqueue_tg(tg, parent_sq);

	throtl_enqueue_tg(tg);



	/* see throtl_add_bio_tg() */

	tg->flags &= ~THROTL_TG_WAS_EMPTY;

}



static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,

				struct throtl_service_queue *parent_sq)

static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw)

{

	struct throtl_service_queue *sq = &tg->service_queue;

	struct bio *bio;
@@ -770,14 +768,13 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw, 
	tg->td->nr_queued[rw]--;



	throtl_charge_bio(tg, bio);

	bio_list_add(&parent_sq->bio_lists[rw], bio);

	bio_list_add(&sq->parent_sq->bio_lists[rw], bio);

	bio->bi_rw |= REQ_THROTTLED;



	throtl_trim_slice(tg, rw);

}



static int throtl_dispatch_tg(struct throtl_grp *tg,

			      struct throtl_service_queue *parent_sq)

static int throtl_dispatch_tg(struct throtl_grp *tg)

{

	struct throtl_service_queue *sq = &tg->service_queue;

	unsigned int nr_reads = 0, nr_writes = 0;
@@ -790,7 +787,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, 
	while ((bio = bio_list_peek(&sq->bio_lists[READ])) &&

	       tg_may_dispatch(tg, bio, NULL)) {



		tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);

		tg_dispatch_one_bio(tg, bio_data_dir(bio));

		nr_reads++;



		if (nr_reads >= max_nr_reads)
@@ -800,7 +797,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, 
	while ((bio = bio_list_peek(&sq->bio_lists[WRITE])) &&

	       tg_may_dispatch(tg, bio, NULL)) {



		tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);

		tg_dispatch_one_bio(tg, bio_data_dir(bio));

		nr_writes++;



		if (nr_writes >= max_nr_writes)
@@ -824,12 +821,12 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq) 
		if (time_before(jiffies, tg->disptime))

			break;



		throtl_dequeue_tg(tg, parent_sq);

		throtl_dequeue_tg(tg);



		nr_disp += throtl_dispatch_tg(tg, parent_sq);

		nr_disp += throtl_dispatch_tg(tg);



		if (sq->nr_queued[0] || sq->nr_queued[1])

			tg_update_disptime(tg, parent_sq);

			tg_update_disptime(tg);



		if (nr_disp >= throtl_quantum)

			break;
@@ -991,7 +988,7 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf, 
	throtl_start_new_slice(tg, 1);



	if (tg->flags & THROTL_TG_PENDING) {

		tg_update_disptime(tg, &td->service_queue);

		tg_update_disptime(tg);

		throtl_schedule_next_dispatch(td);

	}
@@ -1142,12 +1139,12 @@ queue_bio: 
			sq->nr_queued[READ], sq->nr_queued[WRITE]);



	bio_associate_current(bio);

	throtl_add_bio_tg(bio, tg, &q->td->service_queue);

	throtl_add_bio_tg(bio, tg);

	throttled = true;



	/* update @tg's dispatch time if @tg was empty before @bio */

	if (tg->flags & THROTL_TG_WAS_EMPTY) {

		tg_update_disptime(tg, &td->service_queue);

		tg_update_disptime(tg);

		throtl_schedule_next_dispatch(td);

	}
@@ -1179,12 +1176,12 @@ void blk_throtl_drain(struct request_queue *q) 
	while ((tg = throtl_rb_first(parent_sq))) {

		struct throtl_service_queue *sq = &tg->service_queue;



		throtl_dequeue_tg(tg, parent_sq);

		throtl_dequeue_tg(tg);



		while ((bio = bio_list_peek(&sq->bio_lists[READ])))

			tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);

			tg_dispatch_one_bio(tg, bio_data_dir(bio));

		while ((bio = bio_list_peek(&sq->bio_lists[WRITE])))

			tg_dispatch_one_bio(tg, bio_data_dir(bio), parent_sq);

			tg_dispatch_one_bio(tg, bio_data_dir(bio));

	}

	spin_unlock_irq(q->queue_lock);
@@ -1205,7 +1202,7 @@ int blk_throtl_init(struct request_queue *q) 
		return -ENOMEM;



	INIT_DELAYED_WORK(&td->dispatch_work, blk_throtl_dispatch_work_fn);

	throtl_service_queue_init(&td->service_queue);

	throtl_service_queue_init(&td->service_queue, NULL);



	q->td = td;

	td->queue = q;

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