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; | |
4736346b | 24 | struct request *rq; |
5a7c47ee | 25 | |
4736346b GT |
26 | rq = list_first_entry_or_null(&nd->queue, struct request, queuelist); |
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 | } |
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) { |
73 | kobject_put(&eq->kobj); | |
b2fab5ac | 74 | return -ENOMEM; |
d50235b7 JM |
75 | } |
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 | } |
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 LT |
94 | static struct elevator_type elevator_noop = { |
95 | .ops = { | |
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"); |