[net-next-2.6.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;

	if (!list_empty(&nd->queue)) {
		struct request *rq;
		rq = list_entry(nd->queue.next, struct request, queuelist);
		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 int noop_queue_empty(struct request_queue *q)
{
	struct noop_data *nd = q->elevator->elevator_data;

	return list_empty(&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_entry(rq->queuelist.prev, struct request, 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_entry(rq->queuelist.next, struct request, queuelist);
}

static void *noop_init_queue(struct request_queue *q)
{
	struct noop_data *nd;

	nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
	if (!nd)
		return NULL;
	INIT_LIST_HEAD(&nd->queue);
	return nd;
}

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 = {
		.elevator_merge_req_fn		= noop_merged_requests,
		.elevator_dispatch_fn		= noop_dispatch,
		.elevator_add_req_fn		= noop_add_request,
		.elevator_queue_empty_fn	= noop_queue_empty,
		.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)
{
	elv_register(&elevator_noop);

	return 0;
}

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	{
	23	struct noop_data *nd = q->elevator->elevator_data;
	24
	25	if (!list_empty(&nd->queue)) {
	26	struct request *rq;
	27	rq = list_entry(nd->queue.next, struct request, queuelist);
	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
165125e1	42	static int noop_queue_empty(struct request_queue *q)
1da177e4	43	{
5a7c47ee TH	44	struct noop_data *nd = q->elevator->elevator_data;
	45
	46	return list_empty(&nd->queue);
	47	}
	48
	49	static struct request *
165125e1	50	noop_former_request(struct request_queue q, struct request rq)
5a7c47ee TH	51	{
	52	struct noop_data *nd = q->elevator->elevator_data;
	53
	54	if (rq->queuelist.prev == &nd->queue)
	55	return NULL;
	56	return list_entry(rq->queuelist.prev, struct request, queuelist);
	57	}
	58
	59	static struct request *
165125e1	60	noop_latter_request(struct request_queue q, struct request rq)
5a7c47ee TH	61	{
	62	struct noop_data *nd = q->elevator->elevator_data;
	63
	64	if (rq->queuelist.next == &nd->queue)
	65	return NULL;
	66	return list_entry(rq->queuelist.next, struct request, queuelist);
1da177e4 LT	67	}
1da177e4 LT	68
165125e1	69	static void noop_init_queue(struct request_queue q)
1da177e4	70	{
5a7c47ee TH	71	struct noop_data *nd;
5a7c47ee TH	72
b5deef90	73	nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
5a7c47ee	74	if (!nd)
bc1c1169	75	return NULL;
5a7c47ee	76	INIT_LIST_HEAD(&nd->queue);
bc1c1169	77	return nd;
1da177e4 LT	78	}
1da177e4 LT	79
b374d18a	80	static void noop_exit_queue(struct elevator_queue *e)
5a7c47ee TH	81	{
	82	struct noop_data *nd = e->elevator_data;
	83
	84	BUG_ON(!list_empty(&nd->queue));
	85	kfree(nd);
	86	}
	87
1da177e4 LT	88	static struct elevator_type elevator_noop = {
1da177e4 LT	89	.ops = {
5a7c47ee TH	90	.elevator_merge_req_fn = noop_merged_requests,
	91	.elevator_dispatch_fn = noop_dispatch,
	92	.elevator_add_req_fn = noop_add_request,
	93	.elevator_queue_empty_fn = noop_queue_empty,
	94	.elevator_former_req_fn = noop_former_request,
	95	.elevator_latter_req_fn = noop_latter_request,
	96	.elevator_init_fn = noop_init_queue,
	97	.elevator_exit_fn = noop_exit_queue,
1da177e4 LT	98	},
	99	.elevator_name = "noop",
	100	.elevator_owner = THIS_MODULE,
	101	};
	102
	103	static int __init noop_init(void)
	104	{
2fdd82bd AB	105	elv_register(&elevator_noop);
	106
	107	return 0;
1da177e4 LT	108	}
	109
	110	static void __exit noop_exit(void)
	111	{
	112	elv_unregister(&elevator_noop);
	113	}
	114
	115	module_init(noop_init);
	116	module_exit(noop_exit);
	117
	118
	119	MODULE_AUTHOR("Jens Axboe");
	120	MODULE_LICENSE("GPL");
	121	MODULE_DESCRIPTION("No-op IO scheduler");