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 *, int, 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         struct elevator_ops ops;
  98         size_t icq_size;        /* see iocontext.h */
  99         size_t icq_align;       /* ditto */
 100         struct elv_fs_entry *elevator_attrs;
 101         char elevator_name[ELV_NAME_MAX];
 102         struct module *elevator_owner;
 103
 104         /* managed by elevator core */
 105         char icq_cache_name[ELV_NAME_MAX + 5];  /* elvname + "_io_cq" */
 106         struct list_head list;
 107 };
 108
 109 #define ELV_HASH_BITS 6
 110
 111 /*
 112  * each queue has an elevator_queue associated with it
 113  */
 114 struct elevator_queue
 115 {
 116         struct elevator_type *type;
 117         void *elevator_data;
 118         struct kobject kobj;
 119         struct mutex sysfs_lock;
 120         unsigned int registered:1;
 121         DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
 122 };
 123
 124 /*
 125  * block elevator interface
 126  */
 127 extern void elv_dispatch_sort(struct request_queue *, struct request *);
 128 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
 129 extern void elv_add_request(struct request_queue *, struct request *, int);
 130 extern void __elv_add_request(struct request_queue *, struct request *, int);
 131 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
 132 extern void elv_merge_requests(struct request_queue *, struct request *,
 133                                struct request *);
 134 extern void elv_merged_request(struct request_queue *, struct request *, int);
 135 extern void elv_bio_merged(struct request_queue *q, struct request *,
 136                                 struct bio *);
 137 extern void elv_requeue_request(struct request_queue *, struct request *);
 138 extern struct request *elv_former_request(struct request_queue *, struct request *);
 139 extern struct request *elv_latter_request(struct request_queue *, struct request *);
 140 extern int elv_register_queue(struct request_queue *q);
 141 extern void elv_unregister_queue(struct request_queue *q);
 142 extern int elv_may_queue(struct request_queue *, int, int);
 143 extern void elv_completed_request(struct request_queue *, struct request *);
 144 extern int elv_set_request(struct request_queue *q, struct request *rq,
 145                            struct bio *bio, gfp_t gfp_mask);
 146 extern void elv_put_request(struct request_queue *, struct request *);
 147 extern void elv_drain_elevator(struct request_queue *);
 148
 149 /*
 150  * io scheduler registration
 151  */
 152 extern void __init load_default_elevator_module(void);
 153 extern int elv_register(struct elevator_type *);
 154 extern void elv_unregister(struct elevator_type *);
 155
 156 /*
 157  * io scheduler sysfs switching
 158  */
 159 extern ssize_t elv_iosched_show(struct request_queue *, char *);
 160 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 161
 162 extern int elevator_init(struct request_queue *, char *);
 163 extern void elevator_exit(struct elevator_queue *);
 164 extern int elevator_change(struct request_queue *, const char *);
 165 extern bool elv_bio_merge_ok(struct request *, struct bio *);
 166 extern struct elevator_queue *elevator_alloc(struct request_queue *,
 167                                         struct elevator_type *);
 168
 169 /*
 170  * Helper functions.
 171  */
 172 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
 173 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
 174
 175 /*
 176  * rb support functions.
 177  */
 178 extern void elv_rb_add(struct rb_root *, struct request *);
 179 extern void elv_rb_del(struct rb_root *, struct request *);
 180 extern struct request *elv_rb_find(struct rb_root *, sector_t);
 181
 182 /*
 183  * Return values from elevator merger
 184  */
 185 #define ELEVATOR_NO_MERGE       0
 186 #define ELEVATOR_FRONT_MERGE    1
 187 #define ELEVATOR_BACK_MERGE     2
 188
 189 /*
 190  * Insertion selection
 191  */
 192 #define ELEVATOR_INSERT_FRONT   1
 193 #define ELEVATOR_INSERT_BACK    2
 194 #define ELEVATOR_INSERT_SORT    3
 195 #define ELEVATOR_INSERT_REQUEUE 4
 196 #define ELEVATOR_INSERT_FLUSH   5
 197 #define ELEVATOR_INSERT_SORT_MERGE      6
 198
 199 /*
 200  * return values from elevator_may_queue_fn
 201  */
 202 enum {
 203         ELV_MQUEUE_MAY,
 204         ELV_MQUEUE_NO,
 205         ELV_MQUEUE_MUST,
 206 };
 207
 208 #define rq_end_sector(rq)       (blk_rq_pos(rq) + blk_rq_sectors(rq))
 209 #define rb_entry_rq(node)       rb_entry((node), struct request, rb_node)
 210
 211 #define rq_entry_fifo(ptr)      list_entry((ptr), struct request, queuelist)
 212 #define rq_fifo_clear(rq)       list_del_init(&(rq)->queuelist)
 213
 214 #else /* CONFIG_BLOCK */
 215
 216 static inline void load_default_elevator_module(void) { }
 217
 218 #endif /* CONFIG_BLOCK */
 219 #endif