1 #ifndef _LINUX_ELEVATOR_H
2 #define _LINUX_ELEVATOR_H
4 typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
7 typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
9 typedef void (elevator_merged_fn) (request_queue_t *, struct request *);
11 typedef struct request *(elevator_next_req_fn) (request_queue_t *);
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 typedef void (elevator_set_congested_fn) (request_queue_t *);
22 typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, int);
23 typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
25 typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
26 typedef void (elevator_exit_fn) (request_queue_t *, elevator_t *);
30 elevator_merge_fn *elevator_merge_fn;
31 elevator_merged_fn *elevator_merged_fn;
32 elevator_merge_req_fn *elevator_merge_req_fn;
34 elevator_next_req_fn *elevator_next_req_fn;
35 elevator_add_req_fn *elevator_add_req_fn;
36 elevator_remove_req_fn *elevator_remove_req_fn;
37 elevator_requeue_req_fn *elevator_requeue_req_fn;
39 elevator_queue_empty_fn *elevator_queue_empty_fn;
40 elevator_completed_req_fn *elevator_completed_req_fn;
42 elevator_request_list_fn *elevator_former_req_fn;
43 elevator_request_list_fn *elevator_latter_req_fn;
45 elevator_set_req_fn *elevator_set_req_fn;
46 elevator_put_req_fn *elevator_put_req_fn;
48 elevator_may_queue_fn *elevator_may_queue_fn;
49 elevator_set_congested_fn *elevator_set_congested_fn;
51 elevator_init_fn *elevator_init_fn;
52 elevator_exit_fn *elevator_exit_fn;
57 struct kobj_type *elevator_ktype;
58 const char *elevator_name;
62 * block elevator interface
64 extern void elv_add_request(request_queue_t *, struct request *, int, int);
65 extern void __elv_add_request(request_queue_t *, struct request *, int, int);
66 extern int elv_merge(request_queue_t *, struct request **, struct bio *);
67 extern void elv_merge_requests(request_queue_t *, struct request *,
69 extern void elv_merged_request(request_queue_t *, struct request *);
70 extern void elv_remove_request(request_queue_t *, struct request *);
71 extern void elv_requeue_request(request_queue_t *, struct request *);
72 extern int elv_queue_empty(request_queue_t *);
73 extern struct request *elv_next_request(struct request_queue *q);
74 extern struct request *elv_former_request(request_queue_t *, struct request *);
75 extern struct request *elv_latter_request(request_queue_t *, struct request *);
76 extern int elv_register_queue(request_queue_t *q);
77 extern void elv_unregister_queue(request_queue_t *q);
78 extern int elv_may_queue(request_queue_t *, int);
79 extern void elv_set_congested(request_queue_t *);
80 extern void elv_completed_request(request_queue_t *, struct request *);
81 extern int elv_set_request(request_queue_t *, struct request *, int);
82 extern void elv_put_request(request_queue_t *, struct request *);
85 * noop I/O scheduler. always merges, always inserts new request at tail
87 extern elevator_t elevator_noop;
90 * deadline i/o scheduler. uses request time outs to prevent indefinite
93 extern elevator_t iosched_deadline;
96 * anticipatory I/O scheduler
98 extern elevator_t iosched_as;
101 * completely fair queueing I/O scheduler
103 extern elevator_t iosched_cfq;
105 extern int elevator_init(request_queue_t *, elevator_t *);
106 extern void elevator_exit(request_queue_t *);
107 extern int elv_rq_merge_ok(struct request *, struct bio *);
108 extern int elv_try_merge(struct request *, struct bio *);
109 extern int elv_try_last_merge(request_queue_t *, struct bio *);
112 * Return values from elevator merger
114 #define ELEVATOR_NO_MERGE 0
115 #define ELEVATOR_FRONT_MERGE 1
116 #define ELEVATOR_BACK_MERGE 2
119 * Insertion selection
121 #define ELEVATOR_INSERT_FRONT 1
122 #define ELEVATOR_INSERT_BACK 2
123 #define ELEVATOR_INSERT_SORT 3
125 #define RQ_ELV_DATA(rq) (rq)->elevator_private