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
   9 struct io_cq;
  10 struct elevator_type;
  11
  12 /*
  13  * Return values from elevator merger
  14  */
  15 enum elv_merge {
  16         ELEVATOR_NO_MERGE       = 0,
  17         ELEVATOR_FRONT_MERGE    = 1,
  18         ELEVATOR_BACK_MERGE     = 2,
  19         ELEVATOR_DISCARD_MERGE  = 3,
  20 };
  21
  22 typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
  23                                  struct bio *);
  24
  25 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  26
  27 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
  28
  29 typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
  30                                            struct request *, struct bio *);
  31
  32 typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
  33                                           struct request *, struct request *);
  34
  35 typedef void (elevator_bio_merged_fn) (struct request_queue *,
  36                                                 struct request *, struct bio *);
  37
  38 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  39
  40 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  41 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  42 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  43 typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
  44
  45 typedef void (elevator_init_icq_fn) (struct io_cq *);
  46 typedef void (elevator_exit_icq_fn) (struct io_cq *);
  47 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  48                                    struct bio *, gfp_t);
  49 typedef void (elevator_put_req_fn) (struct request *);
  50 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  51 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  52
  53 typedef int (elevator_init_fn) (struct request_queue *,
  54                                 struct elevator_type *e);
  55 typedef void (elevator_exit_fn) (struct elevator_queue *);
  56 typedef void (elevator_registered_fn) (struct request_queue *);
  57
  58 struct elevator_ops
  59 {
  60         elevator_merge_fn *elevator_merge_fn;
  61         elevator_merged_fn *elevator_merged_fn;
  62         elevator_merge_req_fn *elevator_merge_req_fn;
  63         elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
  64         elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
  65         elevator_bio_merged_fn *elevator_bio_merged_fn;
  66
  67         elevator_dispatch_fn *elevator_dispatch_fn;
  68         elevator_add_req_fn *elevator_add_req_fn;
  69         elevator_activate_req_fn *elevator_activate_req_fn;
  70         elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  71
  72         elevator_completed_req_fn *elevator_completed_req_fn;
  73
  74         elevator_request_list_fn *elevator_former_req_fn;
  75         elevator_request_list_fn *elevator_latter_req_fn;
  76
  77         elevator_init_icq_fn *elevator_init_icq_fn;     /* see iocontext.h */
  78         elevator_exit_icq_fn *elevator_exit_icq_fn;     /* ditto */
  79
  80         elevator_set_req_fn *elevator_set_req_fn;
  81         elevator_put_req_fn *elevator_put_req_fn;
  82
  83         elevator_may_queue_fn *elevator_may_queue_fn;
  84
  85         elevator_init_fn *elevator_init_fn;
  86         elevator_exit_fn *elevator_exit_fn;
  87         elevator_registered_fn *elevator_registered_fn;
  88 };
  89
  90 struct blk_mq_alloc_data;
  91 struct blk_mq_hw_ctx;
  92
  93 struct elevator_mq_ops {
  94         int (*init_sched)(struct request_queue *, struct elevator_type *);
  95         void (*exit_sched)(struct elevator_queue *);
  96
  97         bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
  98         bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
  99         int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
 100         void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
 101         void (*requests_merged)(struct request_queue *, struct request *, struct request *);
 102         struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
 103         void (*put_request)(struct request *);
 104         void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
 105         struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
 106         bool (*has_work)(struct blk_mq_hw_ctx *);
 107         void (*completed_request)(struct blk_mq_hw_ctx *, struct request *);
 108         void (*started_request)(struct request *);
 109         void (*requeue_request)(struct request *);
 110         struct request *(*former_request)(struct request_queue *, struct request *);
 111         struct request *(*next_request)(struct request_queue *, struct request *);
 112         int (*get_rq_priv)(struct request_queue *, struct request *, struct bio *);
 113         void (*put_rq_priv)(struct request_queue *, struct request *);
 114         void (*init_icq)(struct io_cq *);
 115         void (*exit_icq)(struct io_cq *);
 116 };
 117
 118 #define ELV_NAME_MAX    (16)
 119
 120 struct elv_fs_entry {
 121         struct attribute attr;
 122         ssize_t (*show)(struct elevator_queue *, char *);
 123         ssize_t (*store)(struct elevator_queue *, const char *, size_t);
 124 };
 125
 126 /*
 127  * identifies an elevator type, such as AS or deadline
 128  */
 129 struct elevator_type
 130 {
 131         /* managed by elevator core */
 132         struct kmem_cache *icq_cache;
 133
 134         /* fields provided by elevator implementation */
 135         union {
 136                 struct elevator_ops sq;
 137                 struct elevator_mq_ops mq;
 138         } ops;
 139         size_t icq_size;        /* see iocontext.h */
 140         size_t icq_align;       /* ditto */
 141         struct elv_fs_entry *elevator_attrs;
 142         char elevator_name[ELV_NAME_MAX];
 143         struct module *elevator_owner;
 144         bool uses_mq;
 145
 146         /* managed by elevator core */
 147         char icq_cache_name[ELV_NAME_MAX + 5];  /* elvname + "_io_cq" */
 148         struct list_head list;
 149 };
 150
 151 #define ELV_HASH_BITS 6
 152
 153 void elv_rqhash_del(struct request_queue *q, struct request *rq);
 154 void elv_rqhash_add(struct request_queue *q, struct request *rq);
 155 void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
 156 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 157
 158 /*
 159  * each queue has an elevator_queue associated with it
 160  */
 161 struct elevator_queue
 162 {
 163         struct elevator_type *type;
 164         void *elevator_data;
 165         struct kobject kobj;
 166         struct mutex sysfs_lock;
 167         unsigned int registered:1;
 168         unsigned int uses_mq:1;
 169         DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 170 };
 171
 172 /*
 173  * block elevator interface
 174  */
 175 extern void elv_dispatch_sort(struct request_queue *, struct request *);
 176 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 177 extern void elv_add_request(struct request_queue *, struct request *, int);
 178 extern void __elv_add_request(struct request_queue *, struct request *, int);
 179 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 180                 struct bio *);
 181 extern void elv_merge_requests(struct request_queue *, struct request *,
 182                                struct request *);
 183 extern void elv_merged_request(struct request_queue *, struct request *,
 184                 enum elv_merge);
 185 extern void elv_bio_merged(struct request_queue *q, struct request *,
 186                                 struct bio *);
 187 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
 188 extern void elv_requeue_request(struct request_queue *, struct request *);
 189 extern struct request *elv_former_request(struct request_queue *, struct request *);
 190 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 191 extern int elv_register_queue(struct request_queue *q);
 192 extern void elv_unregister_queue(struct request_queue *q);
 193 extern int elv_may_queue(struct request_queue *, unsigned int);
 194 extern void elv_completed_request(struct request_queue *, struct request *);
 195 extern int elv_set_request(struct request_queue *q, struct request *rq,
 196                            struct bio *bio, gfp_t gfp_mask);
 197 extern void elv_put_request(struct request_queue *, struct request *);
 198 extern void elv_drain_elevator(struct request_queue *);
 199
 200 /*
 201  * io scheduler registration
 202  */
 203 extern void __init load_default_elevator_module(void);
 204 extern int elv_register(struct elevator_type *);
 205 extern void elv_unregister(struct elevator_type *);
 206
 207 /*
 208  * io scheduler sysfs switching
 209  */
 210 extern ssize_t elv_iosched_show(struct request_queue *, char *);
 211 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 212
 213 extern int elevator_init(struct request_queue *, char *);
 214 extern void elevator_exit(struct elevator_queue *);
 215 extern int elevator_change(struct request_queue *, const char *);
 216 extern bool elv_bio_merge_ok(struct request *, struct bio *);
 217 extern struct elevator_queue *elevator_alloc(struct request_queue *,
 218                                         struct elevator_type *);
 219
 220 /*
 221  * Helper functions.
 222  */
 223 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 224 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 225
 226 /*
 227  * rb support functions.
 228  */
 229 extern void elv_rb_add(struct rb_root *, struct request *);
 230 extern void elv_rb_del(struct rb_root *, struct request *);
 231 extern struct request *elv_rb_find(struct rb_root *, sector_t);
 232
 233 /*
 234  * Insertion selection
 235  */
 236 #define ELEVATOR_INSERT_FRONT   1
 237 #define ELEVATOR_INSERT_BACK    2
 238 #define ELEVATOR_INSERT_SORT    3
 239 #define ELEVATOR_INSERT_REQUEUE 4
 240 #define ELEVATOR_INSERT_FLUSH   5
 241 #define ELEVATOR_INSERT_SORT_MERGE      6
 242
 243 /*
 244  * return values from elevator_may_queue_fn
 245  */
 246 enum {
 247         ELV_MQUEUE_MAY,
 248         ELV_MQUEUE_NO,
 249         ELV_MQUEUE_MUST,
 250 };
 251
 252 #define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 253 #define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 254
 255 #define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 256 #define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 257
 258 #else /* CONFIG_BLOCK */
 259
 260 static inline void load_default_elevator_module(void) { }
 261
 262 #endif /* CONFIG_BLOCK */
 263 #endif