LXR linux/include/linux/elevator.h

   1#ifndef _LINUX_ELEVATOR_H
   2#define _LINUX_ELEVATOR_H
   3
   4#include <linux/percpu.h>
   5
   6#ifdef CONFIG_BLOCK
   7
   8struct io_cq;
   9
  10typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
  11                                 struct bio *);
  12
  13typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  14
  15typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
  16
  17typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
  18
  19typedef void (elevator_bio_merged_fn) (struct request_queue *,
  20                                                struct request *, struct bio *);
  21
  22typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  23
  24typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  25typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  26typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  27typedef int (elevator_may_queue_fn) (struct request_queue *, int);
  28
  29typedef void (elevator_init_icq_fn) (struct io_cq *);
  30typedef void (elevator_exit_icq_fn) (struct io_cq *);
  31typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  32                                   struct bio *, gfp_t);
  33typedef void (elevator_put_req_fn) (struct request *);
  34typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  35typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  36
  37typedef int (elevator_init_fn) (struct request_queue *);
  38typedef void (elevator_exit_fn) (struct elevator_queue *);
  39
  40struct elevator_ops
  41{
  42        elevator_merge_fn *elevator_merge_fn;
  43        elevator_merged_fn *elevator_merged_fn;
  44        elevator_merge_req_fn *elevator_merge_req_fn;
  45        elevator_allow_merge_fn *elevator_allow_merge_fn;
  46        elevator_bio_merged_fn *elevator_bio_merged_fn;
  47
  48        elevator_dispatch_fn *elevator_dispatch_fn;
  49        elevator_add_req_fn *elevator_add_req_fn;
  50        elevator_activate_req_fn *elevator_activate_req_fn;
  51        elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  52
  53        elevator_completed_req_fn *elevator_completed_req_fn;
  54
  55        elevator_request_list_fn *elevator_former_req_fn;
  56        elevator_request_list_fn *elevator_latter_req_fn;
  57
  58        elevator_init_icq_fn *elevator_init_icq_fn;     /* see iocontext.h */
  59        elevator_exit_icq_fn *elevator_exit_icq_fn;     /* ditto */
  60
  61        elevator_set_req_fn *elevator_set_req_fn;
  62        elevator_put_req_fn *elevator_put_req_fn;
  63
  64        elevator_may_queue_fn *elevator_may_queue_fn;
  65
  66        elevator_init_fn *elevator_init_fn;
  67        elevator_exit_fn *elevator_exit_fn;
  68};
  69
  70#define ELV_NAME_MAX    (16)
  71
  72struct elv_fs_entry {
  73        struct attribute attr;
  74        ssize_t (*show)(struct elevator_queue *, char *);
  75        ssize_t (*store)(struct elevator_queue *, const char *, size_t);
  76};
  77
  78/*
  79 * identifies an elevator type, such as AS or deadline
  80 */
  81struct elevator_type
  82{
  83        /* managed by elevator core */
  84        struct kmem_cache *icq_cache;
  85
  86        /* fields provided by elevator implementation */
  87        struct elevator_ops ops;
  88        size_t icq_size;        /* see iocontext.h */
  89        size_t icq_align;       /* ditto */
  90        struct elv_fs_entry *elevator_attrs;
  91        char elevator_name[ELV_NAME_MAX];
  92        struct module *elevator_owner;
  93
  94        /* managed by elevator core */
  95        char icq_cache_name[ELV_NAME_MAX + 5];  /* elvname + "_io_cq" */
  96        struct list_head list;
  97};
  98
  99/*
 100 * each queue has an elevator_queue associated with it
 101 */
 102struct elevator_queue
 103{
 104        struct elevator_type *type;
 105        void *elevator_data;
 106        struct kobject kobj;
 107        struct mutex sysfs_lock;
 108        struct hlist_head *hash;
 109        unsigned int registered:1;
 110};
 111
 112/*
 113 * block elevator interface
 114 */
 115extern void elv_dispatch_sort(struct request_queue *, struct request *);
 116extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 117extern void elv_add_request(struct request_queue *, struct request *, int);
 118extern void __elv_add_request(struct request_queue *, struct request *, int);
 119extern int elv_merge(struct request_queue *, struct request **, struct bio *);
 120extern void elv_merge_requests(struct request_queue *, struct request *,
 121                               struct request *);
 122extern void elv_merged_request(struct request_queue *, struct request *, int);
 123extern void elv_bio_merged(struct request_queue *q, struct request *,
 124                                struct bio *);
 125extern void elv_requeue_request(struct request_queue *, struct request *);
 126extern struct request *elv_former_request(struct request_queue *, struct request *);
 127extern struct request *elv_latter_request(struct request_queue *, struct request *);
 128extern int elv_register_queue(struct request_queue *q);
 129extern void elv_unregister_queue(struct request_queue *q);
 130extern int elv_may_queue(struct request_queue *, int);
 131extern void elv_abort_queue(struct request_queue *);
 132extern void elv_completed_request(struct request_queue *, struct request *);
 133extern int elv_set_request(struct request_queue *q, struct request *rq,
 134                           struct bio *bio, gfp_t gfp_mask);
 135extern void elv_put_request(struct request_queue *, struct request *);
 136extern void elv_drain_elevator(struct request_queue *);
 137
 138/*
 139 * io scheduler registration
 140 */
 141extern int elv_register(struct elevator_type *);
 142extern void elv_unregister(struct elevator_type *);
 143
 144/*
 145 * io scheduler sysfs switching
 146 */
 147extern ssize_t elv_iosched_show(struct request_queue *, char *);
 148extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 149
 150extern int elevator_init(struct request_queue *, char *);
 151extern void elevator_exit(struct elevator_queue *);
 152extern int elevator_change(struct request_queue *, const char *);
 153extern bool elv_rq_merge_ok(struct request *, struct bio *);
 154
 155/*
 156 * Helper functions.
 157 */
 158extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 159extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 160
 161/*
 162 * rb support functions.
 163 */
 164extern void elv_rb_add(struct rb_root *, struct request *);
 165extern void elv_rb_del(struct rb_root *, struct request *);
 166extern struct request *elv_rb_find(struct rb_root *, sector_t);
 167
 168/*
 169 * Return values from elevator merger
 170 */
 171#define ELEVATOR_NO_MERGE       0
 172#define ELEVATOR_FRONT_MERGE    1
 173#define ELEVATOR_BACK_MERGE     2
 174
 175/*
 176 * Insertion selection
 177 */
 178#define ELEVATOR_INSERT_FRONT   1
 179#define ELEVATOR_INSERT_BACK    2
 180#define ELEVATOR_INSERT_SORT    3
 181#define ELEVATOR_INSERT_REQUEUE 4
 182#define ELEVATOR_INSERT_FLUSH   5
 183#define ELEVATOR_INSERT_SORT_MERGE      6
 184
 185/*
 186 * return values from elevator_may_queue_fn
 187 */
 188enum {
 189        ELV_MQUEUE_MAY,
 190        ELV_MQUEUE_NO,
 191        ELV_MQUEUE_MUST,
 192};
 193
 194#define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 195#define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 196
 197/*
 198 * Hack to reuse the csd.list list_head as the fifo time holder while
 199 * the request is in the io scheduler. Saves an unsigned long in rq.
 200 */
 201#define rq_fifo_time(rq)        ((unsigned long) (rq)->csd.list.next)
 202#define rq_set_fifo_time(rq,exp)        ((rq)->csd.list.next = (void *) (exp))
 203#define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 204#define rq_fifo_clear(rq)       do {            \
 205        list_del_init(&(rq)->queuelist);        \
 206        INIT_LIST_HEAD(&(rq)->csd.list);        \
 207        } while (0)
 208
 209#endif /* CONFIG_BLOCK */
 210#endif
 211