[mirror_ubuntu-artful-kernel.git] / block / noop-iosched.c

/*
 * elevator noop
 */
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>

struct noop_data {
	struct list_head queue;
};

static void noop_merged_requests(struct request_queue *q, struct request *rq,
				 struct request *next)
{
	list_del_init(&next->queuelist);
}

static int noop_dispatch(struct request_queue *q, int force)
{
	struct noop_data *nd = q->elevator->elevator_data;
	struct request *rq;

	rq = list_first_entry_or_null(&nd->queue, struct request, queuelist);
	if (rq) {
		list_del_init(&rq->queuelist);
		elv_dispatch_sort(q, rq);
		return 1;
	}
	return 0;
}

static void noop_add_request(struct request_queue *q, struct request *rq)
{
	struct noop_data *nd = q->elevator->elevator_data;

	list_add_tail(&rq->queuelist, &nd->queue);
}

static struct request *
noop_former_request(struct request_queue *q, struct request *rq)
{
	struct noop_data *nd = q->elevator->elevator_data;

	if (rq->queuelist.prev == &nd->queue)
		return NULL;
	return list_prev_entry(rq, queuelist);
}

static struct request *
noop_latter_request(struct request_queue *q, struct request *rq)
{
	struct noop_data *nd = q->elevator->elevator_data;

	if (rq->queuelist.next == &nd->queue)
		return NULL;
	return list_next_entry(rq, queuelist);
}

static int noop_init_queue(struct request_queue *q, struct elevator_type *e)
{
	struct noop_data *nd;
	struct elevator_queue *eq;

	eq = elevator_alloc(q, e);
	if (!eq)
		return -ENOMEM;

	nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
	if (!nd) {
		kobject_put(&eq->kobj);
		return -ENOMEM;
	}
	eq->elevator_data = nd;

	INIT_LIST_HEAD(&nd->queue);

	spin_lock_irq(q->queue_lock);
	q->elevator = eq;
	spin_unlock_irq(q->queue_lock);
	return 0;
}

static void noop_exit_queue(struct elevator_queue *e)
{
	struct noop_data *nd = e->elevator_data;

	BUG_ON(!list_empty(&nd->queue));
	kfree(nd);
}

static struct elevator_type elevator_noop = {
	.ops.sq = {
		.elevator_merge_req_fn		= noop_merged_requests,
		.elevator_dispatch_fn		= noop_dispatch,
		.elevator_add_req_fn		= noop_add_request,
		.elevator_former_req_fn		= noop_former_request,
		.elevator_latter_req_fn		= noop_latter_request,
		.elevator_init_fn		= noop_init_queue,
		.elevator_exit_fn		= noop_exit_queue,
	},
	.elevator_name = "noop",
	.elevator_owner = THIS_MODULE,
};

static int __init noop_init(void)
{
	return elv_register(&elevator_noop);
}

static void __exit noop_exit(void)
{
	elv_unregister(&elevator_noop);
}

module_init(noop_init);
module_exit(noop_exit);


MODULE_AUTHOR("Jens Axboe");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("No-op IO scheduler");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* elevator noop
	3	*/
	4	#include <linux/blkdev.h>
	5	#include <linux/elevator.h>
	6	#include <linux/bio.h>
	7	#include <linux/module.h>
5a0e3ad6	8	#include <linux/slab.h>
1da177e4 LT	9	#include <linux/init.h>
1da177e4 LT	10
5a7c47ee TH	11	struct noop_data {
	12	struct list_head queue;
	13	};
	14
165125e1	15	static void noop_merged_requests(struct request_queue q, struct request rq,
5a7c47ee TH	16	struct request *next)
	17	{
	18	list_del_init(&next->queuelist);
	19	}
	20
165125e1	21	static int noop_dispatch(struct request_queue *q, int force)
5a7c47ee TH	22	{
5a7c47ee TH	23	struct noop_data *nd = q->elevator->elevator_data;
4736346b	24	struct request *rq;
5a7c47ee	25
4736346b GT	26	rq = list_first_entry_or_null(&nd->queue, struct request, queuelist);
4736346b GT	27	if (rq) {
5a7c47ee TH	28	list_del_init(&rq->queuelist);
	29	elv_dispatch_sort(q, rq);
	30	return 1;
	31	}
	32	return 0;
	33	}
	34
165125e1	35	static void noop_add_request(struct request_queue q, struct request rq)
5a7c47ee TH	36	{
	37	struct noop_data *nd = q->elevator->elevator_data;
	38
	39	list_add_tail(&rq->queuelist, &nd->queue);
	40	}
	41
5a7c47ee	42	static struct request *
165125e1	43	noop_former_request(struct request_queue q, struct request rq)
5a7c47ee TH	44	{
	45	struct noop_data *nd = q->elevator->elevator_data;
	46
	47	if (rq->queuelist.prev == &nd->queue)
	48	return NULL;
4736346b	49	return list_prev_entry(rq, queuelist);
5a7c47ee TH	50	}
	51
	52	static struct request *
165125e1	53	noop_latter_request(struct request_queue q, struct request rq)
5a7c47ee TH	54	{
	55	struct noop_data *nd = q->elevator->elevator_data;
	56
	57	if (rq->queuelist.next == &nd->queue)
	58	return NULL;
4736346b	59	return list_next_entry(rq, queuelist);
1da177e4 LT	60	}
1da177e4 LT	61
d50235b7	62	static int noop_init_queue(struct request_queue q, struct elevator_type e)
1da177e4	63	{
5a7c47ee	64	struct noop_data *nd;
d50235b7 JM	65	struct elevator_queue *eq;
	66
	67	eq = elevator_alloc(q, e);
	68	if (!eq)
	69	return -ENOMEM;
5a7c47ee	70
b5deef90	71	nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
d50235b7 JM	72	if (!nd) {
d50235b7 JM	73	kobject_put(&eq->kobj);
b2fab5ac	74	return -ENOMEM;
d50235b7 JM	75	}
d50235b7 JM	76	eq->elevator_data = nd;
b2fab5ac	77
5a7c47ee	78	INIT_LIST_HEAD(&nd->queue);
d50235b7 JM	79
	80	spin_lock_irq(q->queue_lock);
	81	q->elevator = eq;
	82	spin_unlock_irq(q->queue_lock);
b2fab5ac	83	return 0;
1da177e4 LT	84	}
1da177e4 LT	85
b374d18a	86	static void noop_exit_queue(struct elevator_queue *e)
5a7c47ee TH	87	{
	88	struct noop_data *nd = e->elevator_data;
	89
	90	BUG_ON(!list_empty(&nd->queue));
	91	kfree(nd);
	92	}
	93
1da177e4	94	static struct elevator_type elevator_noop = {
c51ca6cf	95	.ops.sq = {
5a7c47ee TH	96	.elevator_merge_req_fn = noop_merged_requests,
	97	.elevator_dispatch_fn = noop_dispatch,
	98	.elevator_add_req_fn = noop_add_request,
5a7c47ee TH	99	.elevator_former_req_fn = noop_former_request,
	100	.elevator_latter_req_fn = noop_latter_request,
	101	.elevator_init_fn = noop_init_queue,
	102	.elevator_exit_fn = noop_exit_queue,
1da177e4 LT	103	},
	104	.elevator_name = "noop",
	105	.elevator_owner = THIS_MODULE,
	106	};
	107
	108	static int __init noop_init(void)
	109	{
3d3c2379	110	return elv_register(&elevator_noop);
1da177e4 LT	111	}
	112
	113	static void __exit noop_exit(void)
	114	{
	115	elv_unregister(&elevator_noop);
	116	}
	117
	118	module_init(noop_init);
	119	module_exit(noop_exit);
	120
	121
	122	MODULE_AUTHOR("Jens Axboe");
	123	MODULE_LICENSE("GPL");
	124	MODULE_DESCRIPTION("No-op IO scheduler");