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> |
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 | ||
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; | |
49 | return list_entry(rq->queuelist.prev, struct request, queuelist); | |
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; | |
59 | return list_entry(rq->queuelist.next, struct request, queuelist); | |
1da177e4 LT |
60 | } |
61 | ||
165125e1 | 62 | static void *noop_init_queue(struct request_queue *q) |
1da177e4 | 63 | { |
5a7c47ee TH |
64 | struct noop_data *nd; |
65 | ||
b5deef90 | 66 | nd = kmalloc_node(sizeof(*nd), GFP_KERNEL, q->node); |
5a7c47ee | 67 | if (!nd) |
bc1c1169 | 68 | return NULL; |
5a7c47ee | 69 | INIT_LIST_HEAD(&nd->queue); |
bc1c1169 | 70 | return nd; |
1da177e4 LT |
71 | } |
72 | ||
b374d18a | 73 | static void noop_exit_queue(struct elevator_queue *e) |
5a7c47ee TH |
74 | { |
75 | struct noop_data *nd = e->elevator_data; | |
76 | ||
77 | BUG_ON(!list_empty(&nd->queue)); | |
78 | kfree(nd); | |
79 | } | |
80 | ||
1da177e4 LT |
81 | static struct elevator_type elevator_noop = { |
82 | .ops = { | |
5a7c47ee TH |
83 | .elevator_merge_req_fn = noop_merged_requests, |
84 | .elevator_dispatch_fn = noop_dispatch, | |
85 | .elevator_add_req_fn = noop_add_request, | |
5a7c47ee TH |
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, | |
1da177e4 LT |
90 | }, |
91 | .elevator_name = "noop", | |
92 | .elevator_owner = THIS_MODULE, | |
93 | }; | |
94 | ||
95 | static int __init noop_init(void) | |
96 | { | |
2fdd82bd AB |
97 | elv_register(&elevator_noop); |
98 | ||
99 | return 0; | |
1da177e4 LT |
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"); |