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Commit 131d08e1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: split the blk-mq case from elevator_init 



There is almost no shared logic, which leads to a very confusing code
flow.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Tested-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent acddf3b3

block/blk-mq.c

+1 −1
Original line number Diff line number Diff line
@@ -2573,7 +2573,7 @@ struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, 
	if (!(set->flags & BLK_MQ_F_NO_SCHED)) {

		int ret;



		ret = elevator_init(q);

		ret = elevator_init_mq(q);

		if (ret)

			return ERR_PTR(ret);

	}

block/blk.h

+1 −0
Original line number Diff line number Diff line
@@ -232,6 +232,7 @@ static inline void elv_deactivate_rq(struct request_queue *q, struct request *rq 
}



int elevator_init(struct request_queue *);

int elevator_init_mq(struct request_queue *q);

void elevator_exit(struct request_queue *, struct elevator_queue *);

int elv_register_queue(struct request_queue *q);

void elv_unregister_queue(struct request_queue *q);

block/elevator.c

+46 −31
Original line number Diff line number Diff line
@@ -199,6 +199,11 @@ static void elevator_release(struct kobject *kobj) 
	kfree(e);

}



/*

 * Use the default elevator specified by config boot param for non-mq devices,

 * or by config option.  Don't try to load modules as we could be running off

 * async and request_module() isn't allowed from async.

 */

int elevator_init(struct request_queue *q)

{

	struct elevator_type *e = NULL;
@@ -212,45 +217,21 @@ int elevator_init(struct request_queue *q) 
	if (unlikely(q->elevator))

		goto out_unlock;



	/*

	 * Use the default elevator specified by config boot param for

	 * non-mq devices, or by config option. Don't try to load modules

	 * as we could be running off async and request_module() isn't

	 * allowed from async.

	 */

	if (!q->mq_ops && *chosen_elevator) {

	if (*chosen_elevator) {

		e = elevator_get(q, chosen_elevator, false);

		if (!e)

			printk(KERN_ERR "I/O scheduler %s not found\n",

							chosen_elevator);

	}



	if (!e) {

		/*

		 * For blk-mq devices, we default to using mq-deadline,

		 * if available, for single queue devices. If deadline

		 * isn't available OR we have multiple queues, default

		 * to "none".

		 */

		if (q->mq_ops) {

			if (q->nr_hw_queues == 1)

				e = elevator_get(q, "mq-deadline", false);

	if (!e)

				goto out_unlock;

		} else

		e = elevator_get(q, CONFIG_DEFAULT_IOSCHED, false);



	if (!e) {

		printk(KERN_ERR

				"Default I/O scheduler not found. " \

				"Using noop.\n");

			"Default I/O scheduler not found. Using noop.\n");

		e = elevator_get(q, "noop", false);

	}

	}



	if (e->uses_mq)

		err = blk_mq_init_sched(q, e);

	else

	err = e->ops.sq.elevator_init_fn(q, e);

	if (err)

		elevator_put(e);
@@ -992,6 +973,40 @@ static int elevator_switch_mq(struct request_queue *q, 
	return ret;

}



/*

 * For blk-mq devices, we default to using mq-deadline, if available, for single

 * queue devices.  If deadline isn't available OR we have multiple queues,

 * default to "none".

 */

int elevator_init_mq(struct request_queue *q)

{

	struct elevator_type *e;

	int err = 0;



	if (q->nr_hw_queues != 1)

		return 0;



	/*

	 * q->sysfs_lock must be held to provide mutual exclusion between

	 * elevator_switch() and here.

	 */

	mutex_lock(&q->sysfs_lock);

	if (unlikely(q->elevator))

		goto out_unlock;



	e = elevator_get(q, "mq-deadline", false);

	if (!e)

		goto out_unlock;



	err = blk_mq_init_sched(q, e);

	if (err)

		elevator_put(e);

out_unlock:

	mutex_unlock(&q->sysfs_lock);

	return err;

}





/*

 * switch to new_e io scheduler. be careful not to introduce deadlocks -

 * we don't free the old io scheduler, before we have allocated what we