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 #ifdef CONFIG_BLK_DEBUG_FS
  12 struct blk_mq_debugfs_attr;
  13 #endif
  14
  15 /*
  16  * Return values from elevator merger
  17  */
  18 enum elv_merge {
  19         ELEVATOR_NO_MERGE       = 0,
  20         ELEVATOR_FRONT_MERGE    = 1,
  21         ELEVATOR_BACK_MERGE     = 2,
  22         ELEVATOR_DISCARD_MERGE  = 3,
  23 };
  24
  25 typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
  26                                  struct bio *);
  27
  28 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
  29
  30 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
  31
  32 typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
  33                                            struct request *, struct bio *);
  34
  35 typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
  36                                           struct request *, struct request *);
  37
  38 typedef void (elevator_bio_merged_fn) (struct request_queue *,
  39                                                 struct request *, struct bio *);
  40
  41 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
  42
  43 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
  44 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
  45 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
  46 typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
  47
  48 typedef void (elevator_init_icq_fn) (struct io_cq *);
  49 typedef void (elevator_exit_icq_fn) (struct io_cq *);
  50 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
  51                                    struct bio *, gfp_t);
  52 typedef void (elevator_put_req_fn) (struct request *);
  53 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
  54 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
  55
  56 typedef int (elevator_init_fn) (struct request_queue *,
  57                                 struct elevator_type *e);
  58 typedef void (elevator_exit_fn) (struct elevator_queue *);
  59 typedef void (elevator_registered_fn) (struct request_queue *);
  60
  61 struct 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
  93 struct blk_mq_alloc_data;
  94 struct blk_mq_hw_ctx;
  95
  96 struct 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
 124 struct 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  */
 133 struct 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
 161 void elv_rqhash_del(struct request_queue *q, struct request *rq);
 162 void elv_rqhash_add(struct request_queue *q, struct request *rq);
 163 void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
 164 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
 165
 166 /*
 167  * each queue has an elevator_queue associated with it
 168  */
 169 struct 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  */
 183 extern void elv_dispatch_sort(struct request_queue *, struct request *);
 184 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 185 extern void elv_add_request(struct request_queue *, struct request *, int);
 186 extern void __elv_add_request(struct request_queue *, struct request *, int);
 187 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
 188                 struct bio *);
 189 extern void elv_merge_requests(struct request_queue *, struct request *,
 190                                struct request *);
 191 extern void elv_merged_request(struct request_queue *, struct request *,
 192                 enum elv_merge);
 193 extern void elv_bio_merged(struct request_queue *q, struct request *,
 194                                 struct bio *);
 195 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
 196 extern void elv_requeue_request(struct request_queue *, struct request *);
 197 extern struct request *elv_former_request(struct request_queue *, struct request *);
 198 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 199 extern int elv_register_queue(struct request_queue *q);
 200 extern void elv_unregister_queue(struct request_queue *q);
 201 extern int elv_may_queue(struct request_queue *, unsigned int);
 202 extern void elv_completed_request(struct request_queue *, struct request *);
 203 extern int elv_set_request(struct request_queue *q, struct request *rq,
 204                            struct bio *bio, gfp_t gfp_mask);
 205 extern void elv_put_request(struct request_queue *, struct request *);
 206 extern void elv_drain_elevator(struct request_queue *);
 207
 208 /*
 209  * io scheduler registration
 210  */
 211 extern void __init load_default_elevator_module(void);
 212 extern int elv_register(struct elevator_type *);
 213 extern void elv_unregister(struct elevator_type *);
 214
 215 /*
 216  * io scheduler sysfs switching
 217  */
 218 extern ssize_t elv_iosched_show(struct request_queue *, char *);
 219 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 220
 221 extern int elevator_init(struct request_queue *, char *);
 222 extern void elevator_exit(struct request_queue *, struct elevator_queue *);
 223 extern bool elv_bio_merge_ok(struct request *, struct bio *);
 224 extern struct elevator_queue *elevator_alloc(struct request_queue *,
 225                                         struct elevator_type *);
 226
 227 /*
 228  * Helper functions.
 229  */
 230 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 231 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 232
 233 /*
 234  * rb support functions.
 235  */
 236 extern void elv_rb_add(struct rb_root *, struct request *);
 237 extern void elv_rb_del(struct rb_root *, struct request *);
 238 extern 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  */
 253 enum {
 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
 267 static inline void load_default_elevator_module(void) { }
 268
 269 #endif /* CONFIG_BLOCK */
 270 #endif