1 #ifndef _LINUX_ELEVATOR_H
2 #define _LINUX_ELEVATOR_H
3
4 typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
5 struct bio *);
6
7 typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
8
9 typedef void (elevator_merged_fn) (request_queue_t *, struct request *);
10
11 typedef struct request *(elevator_next_req_fn) (request_queue_t *);
12
13 typedef void (elevator_add_req_fn) (request_queue_t *, struct request *, int);
14 typedef int (elevator_queue_empty_fn) (request_queue_t *);
15 typedef void (elevator_remove_req_fn) (request_queue_t *, struct request *);
16 typedef void (elevator_requeue_req_fn) (request_queue_t *, struct request *);
17 typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
18 typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
19 typedef int (elevator_may_queue_fn) (request_queue_t *, int);
20
21 typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, int);
22 typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
23
24 typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
25 typedef void (elevator_exit_fn) (elevator_t *);
26
27 struct elevator_ops
28 {
29 elevator_merge_fn *elevator_merge_fn;
30 elevator_merged_fn *elevator_merged_fn;
31 elevator_merge_req_fn *elevator_merge_req_fn;
32
33 elevator_next_req_fn *elevator_next_req_fn;
34 elevator_add_req_fn *elevator_add_req_fn;
35 elevator_remove_req_fn *elevator_remove_req_fn;
36 elevator_requeue_req_fn *elevator_requeue_req_fn;
37
38 elevator_queue_empty_fn *elevator_queue_empty_fn;
39 elevator_completed_req_fn *elevator_completed_req_fn;
40
41 elevator_request_list_fn *elevator_former_req_fn;
42 elevator_request_list_fn *elevator_latter_req_fn;
43
44 elevator_set_req_fn *elevator_set_req_fn;
45 elevator_put_req_fn *elevator_put_req_fn;
46
47 elevator_may_queue_fn *elevator_may_queue_fn;
48
49 elevator_init_fn *elevator_init_fn;
50 elevator_exit_fn *elevator_exit_fn;
51 };
52
53 #define ELV_NAME_MAX (16)
54
55 /*
56 * identifies an elevator type, such as AS or deadline
57 */
58 struct elevator_type
59 {
60 struct list_head list;
61 struct elevator_ops ops;
62 struct elevator_type *elevator_type;
63 struct kobj_type *elevator_ktype;
64 char elevator_name[ELV_NAME_MAX];
65 struct module *elevator_owner;
66 };
67
68 /*
69 * each queue has an elevator_queue assoicated with it
70 */
71 struct elevator_queue
72 {
73 struct elevator_ops *ops;
74 void *elevator_data;
75 struct kobject kobj;
76 struct elevator_type *elevator_type;
77 };
78
79 /*
80 * block elevator interface
81 */
82 extern void elv_add_request(request_queue_t *, struct request *, int, int);
83 extern void __elv_add_request(request_queue_t *, struct request *, int, int);
84 extern int elv_merge(request_queue_t *, struct request **, struct bio *);
85 extern void elv_merge_requests(request_queue_t *, struct request *,
86 struct request *);
87 extern void elv_merged_request(request_queue_t *, struct request *);
88 extern void elv_remove_request(request_queue_t *, struct request *);
89 extern void elv_requeue_request(request_queue_t *, struct request *);
90 extern int elv_queue_empty(request_queue_t *);
91 extern struct request *elv_next_request(struct request_queue *q);
92 extern struct request *elv_former_request(request_queue_t *, struct request *);
93 extern struct request *elv_latter_request(request_queue_t *, struct request *);
94 extern int elv_register_queue(request_queue_t *q);
95 extern void elv_unregister_queue(request_queue_t *q);
96 extern int elv_may_queue(request_queue_t *, int);
97 extern void elv_completed_request(request_queue_t *, struct request *);
98 extern int elv_set_request(request_queue_t *, struct request *, int);
99 extern void elv_put_request(request_queue_t *, struct request *);
100
101 /*
102 * io scheduler registration
103 */
104 extern int elv_register(struct elevator_type *);
105 extern void elv_unregister(struct elevator_type *);
106
107 /*
108 * io scheduler sysfs switching
109 */
110 extern ssize_t elv_iosched_show(request_queue_t *, char *);
111 extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
112
113 extern int elevator_init(request_queue_t *, char *);
114 extern void elevator_exit(elevator_t *);
115 extern int elv_rq_merge_ok(struct request *, struct bio *);
116 extern int elv_try_merge(struct request *, struct bio *);
117 extern int elv_try_last_merge(request_queue_t *, struct bio *);
118
119 /*
120 * Return values from elevator merger
121 */
122 #define ELEVATOR_NO_MERGE 0
123 #define ELEVATOR_FRONT_MERGE 1
124 #define ELEVATOR_BACK_MERGE 2
125
126 /*
127 * Insertion selection
128 */
129 #define ELEVATOR_INSERT_FRONT 1
130 #define ELEVATOR_INSERT_BACK 2
131 #define ELEVATOR_INSERT_SORT 3
132
133 /*
134 * return values from elevator_may_queue_fn
135 */
136 enum {
137 ELV_MQUEUE_MAY,
138 ELV_MQUEUE_NO,
139 ELV_MQUEUE_MUST,
140 };
141
142 #endif
143
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