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1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
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>
5a0e3ad @htejun include cleanup: Update gfp.h and slab.h includes to prepare for brea…
htejun authored Mar 24, 2010
8 #include <linux/slab.h>
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
9 #include <linux/init.h>
10
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
11 struct noop_data {
12 struct list_head queue;
13 };
14
165125e [BLOCK] Get rid of request_queue_t typedef
Jens Axboe authored Jul 24, 2007
15 static void noop_merged_requests(struct request_queue *q, struct request *rq,
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
16 struct request *next)
17 {
18 list_del_init(&next->queuelist);
19 }
20
165125e [BLOCK] Get rid of request_queue_t typedef
Jens Axboe authored Jul 24, 2007
21 static int noop_dispatch(struct request_queue *q, int force)
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
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
165125e [BLOCK] Get rid of request_queue_t typedef
Jens Axboe authored Jul 24, 2007
35 static void noop_add_request(struct request_queue *q, struct request *rq)
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
36 {
37 struct noop_data *nd = q->elevator->elevator_data;
38
39 list_add_tail(&rq->queuelist, &nd->queue);
40 }
41
42 static struct request *
165125e [BLOCK] Get rid of request_queue_t typedef
Jens Axboe authored Jul 24, 2007
43 noop_former_request(struct request_queue *q, struct request *rq)
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
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
52 static struct request *
165125e [BLOCK] Get rid of request_queue_t typedef
Jens Axboe authored Jul 24, 2007
53 noop_latter_request(struct request_queue *q, struct request *rq)
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
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);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
60 }
61
b2fab5a @htejun elevator: make elevator_init_fn() return 0/-errno
htejun authored Mar 5, 2012
62 static int noop_init_queue(struct request_queue *q)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
63 {
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
64 struct noop_data *nd;
65
b5deef9 [PATCH] Make sure all block/io scheduler setups are node aware
Jens Axboe authored Jul 19, 2006
66 nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node);
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
67 if (!nd)
b2fab5a @htejun elevator: make elevator_init_fn() return 0/-errno
htejun authored Mar 5, 2012
68 return -ENOMEM;
69
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
70 INIT_LIST_HEAD(&nd->queue);
b2fab5a @htejun elevator: make elevator_init_fn() return 0/-errno
htejun authored Mar 5, 2012
71 q->elevator->elevator_data = nd;
72 return 0;
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
73 }
74
b374d18 block: get rid of elevator_t typedef
Jens Axboe authored Oct 31, 2008
75 static void noop_exit_queue(struct elevator_queue *e)
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
76 {
77 struct noop_data *nd = e->elevator_data;
78
79 BUG_ON(!list_empty(&nd->queue));
80 kfree(nd);
81 }
82
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
83 static struct elevator_type elevator_noop = {
84 .ops = {
5a7c47e @htejun [BLOCK] noop-iosched: reimplementation of request dispatching
htejun authored Nov 10, 2005
85 .elevator_merge_req_fn = noop_merged_requests,
86 .elevator_dispatch_fn = noop_dispatch,
87 .elevator_add_req_fn = noop_add_request,
88 .elevator_former_req_fn = noop_former_request,
89 .elevator_latter_req_fn = noop_latter_request,
90 .elevator_init_fn = noop_init_queue,
91 .elevator_exit_fn = noop_exit_queue,
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
92 },
93 .elevator_name = "noop",
94 .elevator_owner = THIS_MODULE,
95 };
96
97 static int __init noop_init(void)
98 {
3d3c237 @htejun block, cfq: move icq cache management to block core
htejun authored Dec 14, 2011
99 return elv_register(&elevator_noop);
1da177e Linux-2.6.12-rc2
Linus Torvalds authored Apr 16, 2005
100 }
101
102 static void __exit noop_exit(void)
103 {
104 elv_unregister(&elevator_noop);
105 }
106
107 module_init(noop_init);
108 module_exit(noop_exit);
109
110
111 MODULE_AUTHOR("Jens Axboe");
112 MODULE_LICENSE("GPL");
113 MODULE_DESCRIPTION("No-op IO scheduler");
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