elevator.h 6.5 KB

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  1. #ifndef _LINUX_ELEVATOR_H
  2. #define _LINUX_ELEVATOR_H
  3. #include <linux/percpu.h>
  4. #ifdef CONFIG_BLOCK
  5. typedef int (elevator_merge_fn) (request_queue_t *, struct request **,
  6. struct bio *);
  7. typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
  8. typedef void (elevator_merged_fn) (request_queue_t *, struct request *, int);
  9. typedef int (elevator_allow_merge_fn) (request_queue_t *, struct request *, struct bio *);
  10. typedef int (elevator_dispatch_fn) (request_queue_t *, int);
  11. typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
  12. typedef int (elevator_queue_empty_fn) (request_queue_t *);
  13. typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
  14. typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
  15. typedef int (elevator_may_queue_fn) (request_queue_t *, int);
  16. typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, gfp_t);
  17. typedef void (elevator_put_req_fn) (struct request *);
  18. typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
  19. typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
  20. typedef void *(elevator_init_fn) (request_queue_t *);
  21. typedef void (elevator_exit_fn) (elevator_t *);
  22. struct elevator_ops
  23. {
  24. elevator_merge_fn *elevator_merge_fn;
  25. elevator_merged_fn *elevator_merged_fn;
  26. elevator_merge_req_fn *elevator_merge_req_fn;
  27. elevator_allow_merge_fn *elevator_allow_merge_fn;
  28. elevator_dispatch_fn *elevator_dispatch_fn;
  29. elevator_add_req_fn *elevator_add_req_fn;
  30. elevator_activate_req_fn *elevator_activate_req_fn;
  31. elevator_deactivate_req_fn *elevator_deactivate_req_fn;
  32. elevator_queue_empty_fn *elevator_queue_empty_fn;
  33. elevator_completed_req_fn *elevator_completed_req_fn;
  34. elevator_request_list_fn *elevator_former_req_fn;
  35. elevator_request_list_fn *elevator_latter_req_fn;
  36. elevator_set_req_fn *elevator_set_req_fn;
  37. elevator_put_req_fn *elevator_put_req_fn;
  38. elevator_may_queue_fn *elevator_may_queue_fn;
  39. elevator_init_fn *elevator_init_fn;
  40. elevator_exit_fn *elevator_exit_fn;
  41. void (*trim)(struct io_context *);
  42. };
  43. #define ELV_NAME_MAX (16)
  44. struct elv_fs_entry {
  45. struct attribute attr;
  46. ssize_t (*show)(elevator_t *, char *);
  47. ssize_t (*store)(elevator_t *, const char *, size_t);
  48. };
  49. /*
  50. * identifies an elevator type, such as AS or deadline
  51. */
  52. struct elevator_type
  53. {
  54. struct list_head list;
  55. struct elevator_ops ops;
  56. struct elv_fs_entry *elevator_attrs;
  57. char elevator_name[ELV_NAME_MAX];
  58. struct module *elevator_owner;
  59. };
  60. /*
  61. * each queue has an elevator_queue associated with it
  62. */
  63. struct elevator_queue
  64. {
  65. struct elevator_ops *ops;
  66. void *elevator_data;
  67. struct kobject kobj;
  68. struct elevator_type *elevator_type;
  69. struct mutex sysfs_lock;
  70. struct hlist_head *hash;
  71. };
  72. /*
  73. * block elevator interface
  74. */
  75. extern void elv_dispatch_sort(request_queue_t *, struct request *);
  76. extern void elv_dispatch_add_tail(request_queue_t *, struct request *);
  77. extern void elv_add_request(request_queue_t *, struct request *, int, int);
  78. extern void __elv_add_request(request_queue_t *, struct request *, int, int);
  79. extern void elv_insert(request_queue_t *, struct request *, int);
  80. extern int elv_merge(request_queue_t *, struct request **, struct bio *);
  81. extern void elv_merge_requests(request_queue_t *, struct request *,
  82. struct request *);
  83. extern void elv_merged_request(request_queue_t *, struct request *, int);
  84. extern void elv_dequeue_request(request_queue_t *, struct request *);
  85. extern void elv_requeue_request(request_queue_t *, struct request *);
  86. extern int elv_queue_empty(request_queue_t *);
  87. extern struct request *elv_next_request(struct request_queue *q);
  88. extern struct request *elv_former_request(request_queue_t *, struct request *);
  89. extern struct request *elv_latter_request(request_queue_t *, struct request *);
  90. extern int elv_register_queue(request_queue_t *q);
  91. extern void elv_unregister_queue(request_queue_t *q);
  92. extern int elv_may_queue(request_queue_t *, int);
  93. extern void elv_completed_request(request_queue_t *, struct request *);
  94. extern int elv_set_request(request_queue_t *, struct request *, gfp_t);
  95. extern void elv_put_request(request_queue_t *, struct request *);
  96. /*
  97. * io scheduler registration
  98. */
  99. extern int elv_register(struct elevator_type *);
  100. extern void elv_unregister(struct elevator_type *);
  101. /*
  102. * io scheduler sysfs switching
  103. */
  104. extern ssize_t elv_iosched_show(request_queue_t *, char *);
  105. extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
  106. extern int elevator_init(request_queue_t *, char *);
  107. extern void elevator_exit(elevator_t *);
  108. extern int elv_rq_merge_ok(struct request *, struct bio *);
  109. /*
  110. * Helper functions.
  111. */
  112. extern struct request *elv_rb_former_request(request_queue_t *, struct request *);
  113. extern struct request *elv_rb_latter_request(request_queue_t *, struct request *);
  114. /*
  115. * rb support functions.
  116. */
  117. extern struct request *elv_rb_add(struct rb_root *, struct request *);
  118. extern void elv_rb_del(struct rb_root *, struct request *);
  119. extern struct request *elv_rb_find(struct rb_root *, sector_t);
  120. /*
  121. * Return values from elevator merger
  122. */
  123. #define ELEVATOR_NO_MERGE 0
  124. #define ELEVATOR_FRONT_MERGE 1
  125. #define ELEVATOR_BACK_MERGE 2
  126. /*
  127. * Insertion selection
  128. */
  129. #define ELEVATOR_INSERT_FRONT 1
  130. #define ELEVATOR_INSERT_BACK 2
  131. #define ELEVATOR_INSERT_SORT 3
  132. #define ELEVATOR_INSERT_REQUEUE 4
  133. /*
  134. * return values from elevator_may_queue_fn
  135. */
  136. enum {
  137. ELV_MQUEUE_MAY,
  138. ELV_MQUEUE_NO,
  139. ELV_MQUEUE_MUST,
  140. };
  141. #define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
  142. #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
  143. /*
  144. * Hack to reuse the donelist list_head as the fifo time holder while
  145. * the request is in the io scheduler. Saves an unsigned long in rq.
  146. */
  147. #define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next)
  148. #define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp))
  149. #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
  150. #define rq_fifo_clear(rq) do { \
  151. list_del_init(&(rq)->queuelist); \
  152. INIT_LIST_HEAD(&(rq)->donelist); \
  153. } while (0)
  154. /*
  155. * io context count accounting
  156. */
  157. #define elv_ioc_count_mod(name, __val) \
  158. do { \
  159. preempt_disable(); \
  160. __get_cpu_var(name) += (__val); \
  161. preempt_enable(); \
  162. } while (0)
  163. #define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
  164. #define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
  165. #define elv_ioc_count_read(name) \
  166. ({ \
  167. unsigned long __val = 0; \
  168. int __cpu; \
  169. smp_wmb(); \
  170. for_each_possible_cpu(__cpu) \
  171. __val += per_cpu(name, __cpu); \
  172. __val; \
  173. })
  174. #endif /* CONFIG_BLOCK */
  175. #endif