LXR linux/include/linux/elevator.h

   1#ifndef _LINUX_ELEVATOR_H
   2#define _LINUX_ELEVATOR_H
   3
   4#include <linux/percpu.h>
   5#include <linux/hashtable.h>
   6
   7#ifdef CONFIG_BLOCK
   8
   9struct io_cq;
  10struct elevator_type;
  11
  12typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
  13                                 struct bio *);
  14
  15typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  16
  17typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
  18
  19typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
  20                                           struct request *, struct bio *);
  21
  22typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
  23                                          struct request *, struct request *);
  24
  25typedef void (elevator_bio_merged_fn) (struct request_queue *,
  26                                                struct request *, struct bio *);
  27
  28typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  29
  30typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  31typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  32typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  33typedef int (elevator_may_queue_fn) (struct request_queue *, int, int);
  34
  35typedef void (elevator_init_icq_fn) (struct io_cq *);
  36typedef void (elevator_exit_icq_fn) (struct io_cq *);
  37typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  38                                   struct bio *, gfp_t);
  39typedef void (elevator_put_req_fn) (struct request *);
  40typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  41typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  42
  43typedef int (elevator_init_fn) (struct request_queue *,
  44                                struct elevator_type *e);
  45typedef void (elevator_exit_fn) (struct elevator_queue *);
  46typedef void (elevator_registered_fn) (struct request_queue *);
  47
  48struct elevator_ops
  49{
  50        elevator_merge_fn *elevator_merge_fn;
  51        elevator_merged_fn *elevator_merged_fn;
  52        elevator_merge_req_fn *elevator_merge_req_fn;
  53        elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
  54        elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
  55        elevator_bio_merged_fn *elevator_bio_merged_fn;
  56
  57        elevator_dispatch_fn *elevator_dispatch_fn;
  58        elevator_add_req_fn *elevator_add_req_fn;
  59        elevator_activate_req_fn *elevator_activate_req_fn;
  60        elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  61
  62        elevator_completed_req_fn *elevator_completed_req_fn;
  63
  64        elevator_request_list_fn *elevator_former_req_fn;
  65        elevator_request_list_fn *elevator_latter_req_fn;
  66
  67        elevator_init_icq_fn *elevator_init_icq_fn;     /* see iocontext.h */
  68        elevator_exit_icq_fn *elevator_exit_icq_fn;     /* ditto */
  69
  70        elevator_set_req_fn *elevator_set_req_fn;
  71        elevator_put_req_fn *elevator_put_req_fn;
  72
  73        elevator_may_queue_fn *elevator_may_queue_fn;
  74
  75        elevator_init_fn *elevator_init_fn;
  76        elevator_exit_fn *elevator_exit_fn;
  77        elevator_registered_fn *elevator_registered_fn;
  78};
  79
  80#define ELV_NAME_MAX    (16)
  81
  82struct elv_fs_entry {
  83        struct attribute attr;
  84        ssize_t (*show)(struct elevator_queue *, char *);
  85        ssize_t (*store)(struct elevator_queue *, const char *, size_t);
  86};
  87
  88/*
  89 * identifies an elevator type, such as AS or deadline
  90 */
  91struct elevator_type
  92{
  93        /* managed by elevator core */
  94        struct kmem_cache *icq_cache;
  95
  96        /* fields provided by elevator implementation */
  97        struct elevator_ops ops;
  98        size_t icq_size;        /* see iocontext.h */
  99        size_t icq_align;       /* ditto */
 100        struct elv_fs_entry *elevator_attrs;
 101        char elevator_name[ELV_NAME_MAX];
 102        struct module *elevator_owner;
 103
 104        /* managed by elevator core */
 105        char icq_cache_name[ELV_NAME_MAX + 5];  /* elvname + "_io_cq" */
 106        struct list_head list;
 107};
 108
 109#define ELV_HASH_BITS 6
 110
 111/*
 112 * each queue has an elevator_queue associated with it
 113 */
 114struct elevator_queue
 115{
 116        struct elevator_type *type;
 117        void *elevator_data;
 118        struct kobject kobj;
 119        struct mutex sysfs_lock;
 120        unsigned int registered:1;
 121        DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 122};
 123
 124/*
 125 * block elevator interface
 126 */
 127extern void elv_dispatch_sort(struct request_queue *, struct request *);
 128extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 129extern void elv_add_request(struct request_queue *, struct request *, int);
 130extern void __elv_add_request(struct request_queue *, struct request *, int);
 131extern int elv_merge(struct request_queue *, struct request **, struct bio *);
 132extern void elv_merge_requests(struct request_queue *, struct request *,
 133                               struct request *);
 134extern void elv_merged_request(struct request_queue *, struct request *, int);
 135extern void elv_bio_merged(struct request_queue *q, struct request *,
 136                                struct bio *);
 137extern void elv_requeue_request(struct request_queue *, struct request *);
 138extern struct request *elv_former_request(struct request_queue *, struct request *);
 139extern struct request *elv_latter_request(struct request_queue *, struct request *);
 140extern int elv_register_queue(struct request_queue *q);
 141extern void elv_unregister_queue(struct request_queue *q);
 142extern int elv_may_queue(struct request_queue *, int, int);
 143extern void elv_completed_request(struct request_queue *, struct request *);
 144extern int elv_set_request(struct request_queue *q, struct request *rq,
 145                           struct bio *bio, gfp_t gfp_mask);
 146extern void elv_put_request(struct request_queue *, struct request *);
 147extern void elv_drain_elevator(struct request_queue *);
 148
 149/*
 150 * io scheduler registration
 151 */
 152extern void __init load_default_elevator_module(void);
 153extern int elv_register(struct elevator_type *);
 154extern void elv_unregister(struct elevator_type *);
 155
 156/*
 157 * io scheduler sysfs switching
 158 */
 159extern ssize_t elv_iosched_show(struct request_queue *, char *);
 160extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 161
 162extern int elevator_init(struct request_queue *, char *);
 163extern void elevator_exit(struct elevator_queue *);
 164extern int elevator_change(struct request_queue *, const char *);
 165extern bool elv_bio_merge_ok(struct request *, struct bio *);
 166extern struct elevator_queue *elevator_alloc(struct request_queue *,
 167                                        struct elevator_type *);
 168
 169/*
 170 * Helper functions.
 171 */
 172extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 173extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 174
 175/*
 176 * rb support functions.
 177 */
 178extern void elv_rb_add(struct rb_root *, struct request *);
 179extern void elv_rb_del(struct rb_root *, struct request *);
 180extern struct request *elv_rb_find(struct rb_root *, sector_t);
 181
 182/*
 183 * Return values from elevator merger
 184 */
 185#define ELEVATOR_NO_MERGE       0
 186#define ELEVATOR_FRONT_MERGE    1
 187#define ELEVATOR_BACK_MERGE     2
 188
 189/*
 190 * Insertion selection
 191 */
 192#define ELEVATOR_INSERT_FRONT   1
 193#define ELEVATOR_INSERT_BACK    2
 194#define ELEVATOR_INSERT_SORT    3
 195#define ELEVATOR_INSERT_REQUEUE 4
 196#define ELEVATOR_INSERT_FLUSH   5
 197#define ELEVATOR_INSERT_SORT_MERGE      6
 198
 199/*
 200 * return values from elevator_may_queue_fn
 201 */
 202enum {
 203        ELV_MQUEUE_MAY,
 204        ELV_MQUEUE_NO,
 205        ELV_MQUEUE_MUST,
 206};
 207
 208#define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 209#define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 210
 211#define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 212#define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 213
 214#else /* CONFIG_BLOCK */
 215
 216static inline void load_default_elevator_module(void) { }
 217
 218#endif /* CONFIG_BLOCK */
 219#endif
 220