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