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