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 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, struct bio *);
  20
  21 typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, struct bio *, int);
  22 typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
  23 typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
  24
  25 typedef int (elevator_init_fn) (request_queue_t *, elevator_t *);
  26 typedef void (elevator_exit_fn) (elevator_t *);
  27
  28 struct elevator_ops
  29 {
  30         elevator_merge_fn *elevator_merge_fn;
  31         elevator_merged_fn *elevator_merged_fn;
  32         elevator_merge_req_fn *elevator_merge_req_fn;
  33
  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;
  38         elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  39
  40         elevator_queue_empty_fn *elevator_queue_empty_fn;
  41         elevator_completed_req_fn *elevator_completed_req_fn;
  42
  43         elevator_request_list_fn *elevator_former_req_fn;
  44         elevator_request_list_fn *elevator_latter_req_fn;
  45
  46         elevator_set_req_fn *elevator_set_req_fn;
  47         elevator_put_req_fn *elevator_put_req_fn;
  48
  49         elevator_may_queue_fn *elevator_may_queue_fn;
  50
  51         elevator_init_fn *elevator_init_fn;
  52         elevator_exit_fn *elevator_exit_fn;
  53 };
  54
  55 #define ELV_NAME_MAX    (16)
  56
  57 /*
  58  * identifies an elevator type, such as AS or deadline
  59  */
  60 struct elevator_type
  61 {
  62         struct list_head list;
  63         struct elevator_ops ops;
  64         struct elevator_type *elevator_type;
  65         struct kobj_type *elevator_ktype;
  66         char elevator_name[ELV_NAME_MAX];
  67         struct module *elevator_owner;
  68 };
  69
  70 /*
  71  * each queue has an elevator_queue assoicated with it
  72  */
  73 struct elevator_queue
  74 {
  75         struct elevator_ops *ops;
  76         void *elevator_data;
  77         struct kobject kobj;
  78         struct elevator_type *elevator_type;
  79 };
  80
  81 /*
  82  * block elevator interface
  83  */
  84 extern void elv_add_request(request_queue_t *, struct request *, int, int);
  85 extern void __elv_add_request(request_queue_t *, struct request *, int, 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_remove_request(request_queue_t *, struct request *);
  91 extern void elv_requeue_request(request_queue_t *, struct request *);
  92 extern void elv_deactivate_request(request_queue_t *, struct request *);
  93 extern int elv_queue_empty(request_queue_t *);
  94 extern struct request *elv_next_request(struct request_queue *q);
  95 extern struct request *elv_former_request(request_queue_t *, struct request *);
  96 extern struct request *elv_latter_request(request_queue_t *, struct request *);
  97 extern int elv_register_queue(request_queue_t *q);
  98 extern void elv_unregister_queue(request_queue_t *q);
  99 extern int elv_may_queue(request_queue_t *, int, struct bio *);
 100 extern void elv_completed_request(request_queue_t *, struct request *);
 101 extern int elv_set_request(request_queue_t *, struct request *, struct bio *, int);
 102 extern void elv_put_request(request_queue_t *, struct request *);
 103
 104 /*
 105  * io scheduler registration
 106  */
 107 extern int elv_register(struct elevator_type *);
 108 extern void elv_unregister(struct elevator_type *);
 109
 110 /*
 111  * io scheduler sysfs switching
 112  */
 113 extern ssize_t elv_iosched_show(request_queue_t *, char *);
 114 extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
 115
 116 extern int elevator_init(request_queue_t *, char *);
 117 extern void elevator_exit(elevator_t *);
 118 extern int elv_rq_merge_ok(struct request *, struct bio *);
 119 extern int elv_try_merge(struct request *, struct bio *);
 120 extern int elv_try_last_merge(request_queue_t *, struct bio *);
 121
 122 /*
 123  * Return values from elevator merger
 124  */
 125 #define ELEVATOR_NO_MERGE       0
 126 #define ELEVATOR_FRONT_MERGE    1
 127 #define ELEVATOR_BACK_MERGE     2
 128
 129 /*
 130  * Insertion selection
 131  */
 132 #define ELEVATOR_INSERT_FRONT   1
 133 #define ELEVATOR_INSERT_BACK    2
 134 #define ELEVATOR_INSERT_SORT    3
 135
 136 /*
 137  * return values from elevator_may_queue_fn
 138  */
 139 enum {
 140         ELV_MQUEUE_MAY,
 141         ELV_MQUEUE_NO,
 142         ELV_MQUEUE_MUST,
 143 };
 144
 145 #endif