include/linux/elevator.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_ELEVATOR_H
   3 #define _LINUX_ELEVATOR_H
   4
   5 #include <linux/percpu.h>
   6 #include <linux/hashtable.h>
   7
   8 #ifdef CONFIG_BLOCK
   9
  10 struct io_cq;
  11 struct elevator_type;
  12 #ifdef CONFIG_BLK_DEBUG_FS
  13 struct blk_mq_debugfs_attr;
  14 #endif
  15
  16 /*
  17  * Return values from elevator merger
  18  */
  19 enum elv_merge {
  20         ELEVATOR_NO_MERGE       = 0,
  21         ELEVATOR_FRONT_MERGE    = 1,
  22         ELEVATOR_BACK_MERGE     = 2,
  23         ELEVATOR_DISCARD_MERGE  = 3,
  24 };
  25
  26 typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
  27                                  struct bio *);
  28
  29 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  30
  31 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
  32
  33 typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
  34                                            struct request *, struct bio *);
  35
  36 typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
  37                                           struct request *, struct request *);
  38
  39 typedef void (elevator_bio_merged_fn) (struct request_queue *,
  40                                                 struct request *, struct bio *);
  41
  42 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  43
  44 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  45 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  46 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  47 typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
  48
  49 typedef void (elevator_init_icq_fn) (struct io_cq *);
  50 typedef void (elevator_exit_icq_fn) (struct io_cq *);
  51 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  52                                    struct bio *, gfp_t);
  53 typedef void (elevator_put_req_fn) (struct request *);
  54 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  55 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  56
  57 typedef int (elevator_init_fn) (struct request_queue *,
  58                                 struct elevator_type *e);
  59 typedef void (elevator_exit_fn) (struct elevator_queue *);
  60 typedef void (elevator_registered_fn) (struct request_queue *);
  61
  62 struct elevator_ops
  63 {
  64         elevator_merge_fn *elevator_merge_fn;
  65         elevator_merged_fn *elevator_merged_fn;
  66         elevator_merge_req_fn *elevator_merge_req_fn;
  67         elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
  68         elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
  69         elevator_bio_merged_fn *elevator_bio_merged_fn;
  70
  71         elevator_dispatch_fn *elevator_dispatch_fn;
  72         elevator_add_req_fn *elevator_add_req_fn;
  73         elevator_activate_req_fn *elevator_activate_req_fn;
  74         elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  75
  76         elevator_completed_req_fn *elevator_completed_req_fn;
  77
  78         elevator_request_list_fn *elevator_former_req_fn;
  79         elevator_request_list_fn *elevator_latter_req_fn;
  80
  81         elevator_init_icq_fn *elevator_init_icq_fn;     /* see iocontext.h */
  82         elevator_exit_icq_fn *elevator_exit_icq_fn;     /* ditto */
  83
  84         elevator_set_req_fn *elevator_set_req_fn;
  85         elevator_put_req_fn *elevator_put_req_fn;
  86
  87         elevator_may_queue_fn *elevator_may_queue_fn;
  88
  89         elevator_init_fn *elevator_init_fn;
  90         elevator_exit_fn *elevator_exit_fn;
  91         elevator_registered_fn *elevator_registered_fn;
  92 };
  93
  94 struct blk_mq_alloc_data;
  95 struct blk_mq_hw_ctx;
  96
  97 struct elevator_mq_ops {
  98         int (*init_sched)(struct request_queue *, struct elevator_type *);
  99         void (*exit_sched)(struct elevator_queue *);
 100         int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 101         void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
 102
 103         bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
 104         bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
 105         int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
 106         void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
 107         void (*requests_merged)(struct request_queue *, struct request *, struct request *);
 108         void (*limit_depth)(unsigned int, struct blk_mq_alloc_data *);
 109         void (*prepare_request)(struct request *, struct bio *bio);
 110         void (*finish_request)(struct request *);
 111         void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
 112         struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
 113         bool (*has_work)(struct blk_mq_hw_ctx *);
 114         void (*completed_request)(struct request *);
 115         void (*started_request)(struct request *);
 116         void (*requeue_request)(struct request *);
 117         struct request *(*former_request)(struct request_queue *, struct request *);
 118         struct request *(*next_request)(struct request_queue *, struct request *);
 119         void (*init_icq)(struct io_cq *);
 120         void (*exit_icq)(struct io_cq *);
 121 };
 122
 123 #define ELV_NAME_MAX    (16)
 124
 125 struct elv_fs_entry {
 126         struct attribute attr;
 127         ssize_t (*show)(struct elevator_queue *, char *);
 128         ssize_t (*store)(struct elevator_queue *, const char *, size_t);
 129 };
 130
 131 /*
 132  * identifies an elevator type, such as AS or deadline
 133  */
 134 struct elevator_type
 135 {
 136         /* managed by elevator core */
 137         struct kmem_cache *icq_cache;
 138
 139         /* fields provided by elevator implementation */
 140         union {
 141                 struct elevator_ops sq;
 142                 struct elevator_mq_ops mq;
 143         } ops;
 144         size_t icq_size;        /* see iocontext.h */
 145         size_t icq_align;       /* ditto */
 146         struct elv_fs_entry *elevator_attrs;
 147         char elevator_name[ELV_NAME_MAX];
 148         const char *elevator_alias;
 149         struct module *elevator_owner;
 150         bool uses_mq;
 151 #ifdef CONFIG_BLK_DEBUG_FS
 152         const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
 153         const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
 154 #endif
 155
 156         /* managed by elevator core */
 157         char icq_cache_name[ELV_NAME_MAX + 6];  /* elvname + "_io_cq" */
 158         struct list_head list;
 159 };
 160
 161 #define ELV_HASH_BITS 6
 162
 163 void elv_rqhash_del(struct request_queue *q, struct request *rq);
 164 void elv_rqhash_add(struct request_queue *q, struct request *rq);
 165 void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
 166 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 167
 168 /*
 169  * each queue has an elevator_queue associated with it
 170  */
 171 struct elevator_queue
 172 {
 173         struct elevator_type *type;
 174         void *elevator_data;
 175         struct kobject kobj;
 176         struct mutex sysfs_lock;
 177         unsigned int registered:1;
 178         unsigned int uses_mq:1;
 179         DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 180 };
 181
 182 /*
 183  * block elevator interface
 184  */
 185 extern void elv_dispatch_sort(struct request_queue *, struct request *);
 186 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 187 extern void elv_add_request(struct request_queue *, struct request *, int);
 188 extern void __elv_add_request(struct request_queue *, struct request *, int);
 189 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 190                 struct bio *);
 191 extern void elv_merge_requests(struct request_queue *, struct request *,
 192                                struct request *);
 193 extern void elv_merged_request(struct request_queue *, struct request *,
 194                 enum elv_merge);
 195 extern void elv_bio_merged(struct request_queue *q, struct request *,
 196                                 struct bio *);
 197 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
 198 extern void elv_requeue_request(struct request_queue *, struct request *);
 199 extern struct request *elv_former_request(struct request_queue *, struct request *);
 200 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 201 extern int elv_register_queue(struct request_queue *q);
 202 extern void elv_unregister_queue(struct request_queue *q);
 203 extern int elv_may_queue(struct request_queue *, unsigned int);
 204 extern void elv_completed_request(struct request_queue *, struct request *);
 205 extern int elv_set_request(struct request_queue *q, struct request *rq,
 206                            struct bio *bio, gfp_t gfp_mask);
 207 extern void elv_put_request(struct request_queue *, struct request *);
 208 extern void elv_drain_elevator(struct request_queue *);
 209
 210 /*
 211  * io scheduler registration
 212  */
 213 extern void __init load_default_elevator_module(void);
 214 extern int elv_register(struct elevator_type *);
 215 extern void elv_unregister(struct elevator_type *);
 216
 217 /*
 218  * io scheduler sysfs switching
 219  */
 220 extern ssize_t elv_iosched_show(struct request_queue *, char *);
 221 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 222
 223 extern int elevator_init(struct request_queue *, char *);
 224 extern void elevator_exit(struct request_queue *, struct elevator_queue *);
 225 extern bool elv_bio_merge_ok(struct request *, struct bio *);
 226 extern struct elevator_queue *elevator_alloc(struct request_queue *,
 227                                         struct elevator_type *);
 228
 229 /*
 230  * Helper functions.
 231  */
 232 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 233 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 234
 235 /*
 236  * rb support functions.
 237  */
 238 extern void elv_rb_add(struct rb_root *, struct request *);
 239 extern void elv_rb_del(struct rb_root *, struct request *);
 240 extern struct request *elv_rb_find(struct rb_root *, sector_t);
 241
 242 /*
 243  * Insertion selection
 244  */
 245 #define ELEVATOR_INSERT_FRONT   1
 246 #define ELEVATOR_INSERT_BACK    2
 247 #define ELEVATOR_INSERT_SORT    3
 248 #define ELEVATOR_INSERT_REQUEUE 4
 249 #define ELEVATOR_INSERT_FLUSH   5
 250 #define ELEVATOR_INSERT_SORT_MERGE      6
 251
 252 /*
 253  * return values from elevator_may_queue_fn
 254  */
 255 enum {
 256         ELV_MQUEUE_MAY,
 257         ELV_MQUEUE_NO,
 258         ELV_MQUEUE_MUST,
 259 };
 260
 261 #define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 262 #define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 263
 264 #define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 265 #define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 266
 267 #else /* CONFIG_BLOCK */
 268
 269 static inline void load_default_elevator_module(void) { }
 270
 271 #endif /* CONFIG_BLOCK */
 272 #endif