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