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#ifdef CONFIG_BLK_DEBUG_FS
  12struct blk_mq_debugfs_attr;
  13#endif
  14
  15/*
  16 * Return values from elevator merger
  17 */
  18enum elv_merge {
  19        ELEVATOR_NO_MERGE       = 0,
  20        ELEVATOR_FRONT_MERGE    = 1,
  21        ELEVATOR_BACK_MERGE     = 2,
  22        ELEVATOR_DISCARD_MERGE  = 3,
  23};
  24
  25typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
  26                                 struct bio *);
  27
  28typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  29
  30typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
  31
  32typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
  33                                           struct request *, struct bio *);
  34
  35typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
  36                                          struct request *, struct request *);
  37
  38typedef void (elevator_bio_merged_fn) (struct request_queue *,
  39                                                struct request *, struct bio *);
  40
  41typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  42
  43typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  44typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  45typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  46typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
  47
  48typedef void (elevator_init_icq_fn) (struct io_cq *);
  49typedef void (elevator_exit_icq_fn) (struct io_cq *);
  50typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  51                                   struct bio *, gfp_t);
  52typedef void (elevator_put_req_fn) (struct request *);
  53typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  54typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  55
  56typedef int (elevator_init_fn) (struct request_queue *,
  57                                struct elevator_type *e);
  58typedef void (elevator_exit_fn) (struct elevator_queue *);
  59typedef void (elevator_registered_fn) (struct request_queue *);
  60
  61struct elevator_ops
  62{
  63        elevator_merge_fn *elevator_merge_fn;
  64        elevator_merged_fn *elevator_merged_fn;
  65        elevator_merge_req_fn *elevator_merge_req_fn;
  66        elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
  67        elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
  68        elevator_bio_merged_fn *elevator_bio_merged_fn;
  69
  70        elevator_dispatch_fn *elevator_dispatch_fn;
  71        elevator_add_req_fn *elevator_add_req_fn;
  72        elevator_activate_req_fn *elevator_activate_req_fn;
  73        elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  74
  75        elevator_completed_req_fn *elevator_completed_req_fn;
  76
  77        elevator_request_list_fn *elevator_former_req_fn;
  78        elevator_request_list_fn *elevator_latter_req_fn;
  79
  80        elevator_init_icq_fn *elevator_init_icq_fn;     /* see iocontext.h */
  81        elevator_exit_icq_fn *elevator_exit_icq_fn;     /* ditto */
  82
  83        elevator_set_req_fn *elevator_set_req_fn;
  84        elevator_put_req_fn *elevator_put_req_fn;
  85
  86        elevator_may_queue_fn *elevator_may_queue_fn;
  87
  88        elevator_init_fn *elevator_init_fn;
  89        elevator_exit_fn *elevator_exit_fn;
  90        elevator_registered_fn *elevator_registered_fn;
  91};
  92
  93struct blk_mq_alloc_data;
  94struct blk_mq_hw_ctx;
  95
  96struct elevator_mq_ops {
  97        int (*init_sched)(struct request_queue *, struct elevator_type *);
  98        void (*exit_sched)(struct elevator_queue *);
  99        int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 100        void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 101
 102        bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
 103        bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
 104        int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
 105        void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
 106        void (*requests_merged)(struct request_queue *, struct request *, struct request *);
 107        void (*limit_depth)(unsigned int, struct blk_mq_alloc_data *);
 108        void (*prepare_request)(struct request *, struct bio *bio);
 109        void (*finish_request)(struct request *);
 110        void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
 111        struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
 112        bool (*has_work)(struct blk_mq_hw_ctx *);
 113        void (*completed_request)(struct request *);
 114        void (*started_request)(struct request *);
 115        void (*requeue_request)(struct request *);
 116        struct request *(*former_request)(struct request_queue *, struct request *);
 117        struct request *(*next_request)(struct request_queue *, struct request *);
 118        void (*init_icq)(struct io_cq *);
 119        void (*exit_icq)(struct io_cq *);
 120};
 121
 122#define ELV_NAME_MAX    (16)
 123
 124struct elv_fs_entry {
 125        struct attribute attr;
 126        ssize_t (*show)(struct elevator_queue *, char *);
 127        ssize_t (*store)(struct elevator_queue *, const char *, size_t);
 128};
 129
 130/*
 131 * identifies an elevator type, such as AS or deadline
 132 */
 133struct elevator_type
 134{
 135        /* managed by elevator core */
 136        struct kmem_cache *icq_cache;
 137
 138        /* fields provided by elevator implementation */
 139        union {
 140                struct elevator_ops sq;
 141                struct elevator_mq_ops mq;
 142        } ops;
 143        size_t icq_size;        /* see iocontext.h */
 144        size_t icq_align;       /* ditto */
 145        struct elv_fs_entry *elevator_attrs;
 146        char elevator_name[ELV_NAME_MAX];
 147        struct module *elevator_owner;
 148        bool uses_mq;
 149#ifdef CONFIG_BLK_DEBUG_FS
 150        const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
 151        const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
 152#endif
 153
 154        /* managed by elevator core */
 155        char icq_cache_name[ELV_NAME_MAX + 6];  /* elvname + "_io_cq" */
 156        struct list_head list;
 157};
 158
 159#define ELV_HASH_BITS 6
 160
 161void elv_rqhash_del(struct request_queue *q, struct request *rq);
 162void elv_rqhash_add(struct request_queue *q, struct request *rq);
 163void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
 164struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 165
 166/*
 167 * each queue has an elevator_queue associated with it
 168 */
 169struct elevator_queue
 170{
 171        struct elevator_type *type;
 172        void *elevator_data;
 173        struct kobject kobj;
 174        struct mutex sysfs_lock;
 175        unsigned int registered:1;
 176        unsigned int uses_mq:1;
 177        DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 178};
 179
 180/*
 181 * block elevator interface
 182 */
 183extern void elv_dispatch_sort(struct request_queue *, struct request *);
 184extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 185extern void elv_add_request(struct request_queue *, struct request *, int);
 186extern void __elv_add_request(struct request_queue *, struct request *, int);
 187extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 188                struct bio *);
 189extern void elv_merge_requests(struct request_queue *, struct request *,
 190                               struct request *);
 191extern void elv_merged_request(struct request_queue *, struct request *,
 192                enum elv_merge);
 193extern void elv_bio_merged(struct request_queue *q, struct request *,
 194                                struct bio *);
 195extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
 196extern void elv_requeue_request(struct request_queue *, struct request *);
 197extern struct request *elv_former_request(struct request_queue *, struct request *);
 198extern struct request *elv_latter_request(struct request_queue *, struct request *);
 199extern int elv_register_queue(struct request_queue *q);
 200extern void elv_unregister_queue(struct request_queue *q);
 201extern int elv_may_queue(struct request_queue *, unsigned int);
 202extern void elv_completed_request(struct request_queue *, struct request *);
 203extern int elv_set_request(struct request_queue *q, struct request *rq,
 204                           struct bio *bio, gfp_t gfp_mask);
 205extern void elv_put_request(struct request_queue *, struct request *);
 206extern void elv_drain_elevator(struct request_queue *);
 207
 208/*
 209 * io scheduler registration
 210 */
 211extern void __init load_default_elevator_module(void);
 212extern int elv_register(struct elevator_type *);
 213extern void elv_unregister(struct elevator_type *);
 214
 215/*
 216 * io scheduler sysfs switching
 217 */
 218extern ssize_t elv_iosched_show(struct request_queue *, char *);
 219extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 220
 221extern int elevator_init(struct request_queue *, char *);
 222extern void elevator_exit(struct request_queue *, struct elevator_queue *);
 223extern bool elv_bio_merge_ok(struct request *, struct bio *);
 224extern struct elevator_queue *elevator_alloc(struct request_queue *,
 225                                        struct elevator_type *);
 226
 227/*
 228 * Helper functions.
 229 */
 230extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 231extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 232
 233/*
 234 * rb support functions.
 235 */
 236extern void elv_rb_add(struct rb_root *, struct request *);
 237extern void elv_rb_del(struct rb_root *, struct request *);
 238extern struct request *elv_rb_find(struct rb_root *, sector_t);
 239
 240/*
 241 * Insertion selection
 242 */
 243#define ELEVATOR_INSERT_FRONT   1
 244#define ELEVATOR_INSERT_BACK    2
 245#define ELEVATOR_INSERT_SORT    3
 246#define ELEVATOR_INSERT_REQUEUE 4
 247#define ELEVATOR_INSERT_FLUSH   5
 248#define ELEVATOR_INSERT_SORT_MERGE      6
 249
 250/*
 251 * return values from elevator_may_queue_fn
 252 */
 253enum {
 254        ELV_MQUEUE_MAY,
 255        ELV_MQUEUE_NO,
 256        ELV_MQUEUE_MUST,
 257};
 258
 259#define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 260#define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 261
 262#define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 263#define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 264
 265#else /* CONFIG_BLOCK */
 266
 267static inline void load_default_elevator_module(void) { }
 268
 269#endif /* CONFIG_BLOCK */
 270#endif
 271