include/linux/elevator.h

   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 int (elevator_dispatch_fn) (request_queue_t *, int);
  12
  13 typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
  14 typedef int (elevator_queue_empty_fn) (request_queue_t *);
  15 typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
  16 typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
  17 typedef int (elevator_may_queue_fn) (request_queue_t *, int, struct bio *);
  18
  19 typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, gfp_t);
  20 typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
  21 typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
  22 typedef void (elevator_deactivate_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_dispatch_fn *elevator_dispatch_fn;
  34         elevator_add_req_fn *elevator_add_req_fn;
  35         elevator_activate_req_fn *elevator_activate_req_fn;
  36         elevator_deactivate_req_fn *elevator_deactivate_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 associated 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_dispatch_sort(request_queue_t *, struct request *);
  83 extern void elv_add_request(request_queue_t *, struct request *, int, int);
  84 extern void __elv_add_request(request_queue_t *, struct request *, int, int);
  85 extern void elv_insert(request_queue_t *, struct request *, int);
  86 extern int elv_merge(request_queue_t *, struct request **, struct bio *);
  87 extern void elv_merge_requests(request_queue_t *, struct request *,
  88                                struct request *);
  89 extern void elv_merged_request(request_queue_t *, struct request *);
  90 extern void elv_dequeue_request(request_queue_t *, struct request *);
  91 extern void elv_requeue_request(request_queue_t *, struct request *);
  92 extern int elv_queue_empty(request_queue_t *);
  93 extern struct request *elv_next_request(struct request_queue *q);
  94 extern struct request *elv_former_request(request_queue_t *, struct request *);
  95 extern struct request *elv_latter_request(request_queue_t *, struct request *);
  96 extern int elv_register_queue(request_queue_t *q);
  97 extern void elv_unregister_queue(request_queue_t *q);
  98 extern int elv_may_queue(request_queue_t *, int, struct bio *);
  99 extern void elv_completed_request(request_queue_t *, struct request *);
 100 extern int elv_set_request(request_queue_t *, struct request *, struct bio *, gfp_t);
 101 extern void elv_put_request(request_queue_t *, struct request *);
 102
 103 /*
 104  * io scheduler registration
 105  */
 106 extern int elv_register(struct elevator_type *);
 107 extern void elv_unregister(struct elevator_type *);
 108
 109 /*
 110  * io scheduler sysfs switching
 111  */
 112 extern ssize_t elv_iosched_show(request_queue_t *, char *);
 113 extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
 114
 115 extern int elevator_init(request_queue_t *, char *);
 116 extern void elevator_exit(elevator_t *);
 117 extern int elv_rq_merge_ok(struct request *, 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 #define ELEVATOR_INSERT_REQUEUE 4
 133
 134 /*
 135  * return values from elevator_may_queue_fn
 136  */
 137 enum {
 138         ELV_MQUEUE_MAY,
 139         ELV_MQUEUE_NO,
 140         ELV_MQUEUE_MUST,
 141 };
 142
 143 #define rq_end_sector(rq)       ((rq)->sector + (rq)->nr_sectors)
 144
 145 #endif