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