1 #ifndef _LINUX_ELEVATOR_H
2 #define _LINUX_ELEVATOR_H
4 #include <linux/percpu.h>
10 typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
13 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
15 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
17 typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
19 typedef void (elevator_bio_merged_fn) (struct request_queue *,
20 struct request *, struct bio *);
22 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
24 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
25 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
26 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
27 typedef int (elevator_may_queue_fn) (struct request_queue *, int);
29 typedef void (elevator_exit_icq_fn) (struct io_cq *);
30 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
31 typedef void (elevator_put_req_fn) (struct request *);
32 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
33 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
35 typedef void *(elevator_init_fn) (struct request_queue *);
36 typedef void (elevator_exit_fn) (struct elevator_queue *);
40 elevator_merge_fn *elevator_merge_fn;
41 elevator_merged_fn *elevator_merged_fn;
42 elevator_merge_req_fn *elevator_merge_req_fn;
43 elevator_allow_merge_fn *elevator_allow_merge_fn;
46 * Used for both plugged list and elevator merging and in the
47 * former case called without queue_lock. Read comment on top of
48 * attempt_plug_merge() for details.
50 elevator_bio_merged_fn *elevator_bio_merged_fn;
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;
57 elevator_completed_req_fn *elevator_completed_req_fn;
59 elevator_request_list_fn *elevator_former_req_fn;
60 elevator_request_list_fn *elevator_latter_req_fn;
62 elevator_exit_icq_fn *elevator_exit_icq_fn;
64 elevator_set_req_fn *elevator_set_req_fn;
65 elevator_put_req_fn *elevator_put_req_fn;
67 elevator_may_queue_fn *elevator_may_queue_fn;
69 elevator_init_fn *elevator_init_fn;
70 elevator_exit_fn *elevator_exit_fn;
73 #define ELV_NAME_MAX (16)
76 struct attribute attr;
77 ssize_t (*show)(struct elevator_queue *, char *);
78 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
82 * identifies an elevator type, such as AS or deadline
86 /* managed by elevator core */
87 struct kmem_cache *icq_cache;
89 /* fields provided by elevator implementation */
90 struct elevator_ops ops;
93 struct elv_fs_entry *elevator_attrs;
94 char elevator_name[ELV_NAME_MAX];
95 struct module *elevator_owner;
97 /* managed by elevator core */
98 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
99 struct list_head list;
103 * each queue has an elevator_queue associated with it
105 struct elevator_queue
107 struct elevator_type *type;
110 struct mutex sysfs_lock;
111 struct hlist_head *hash;
112 unsigned int registered:1;
116 * block elevator interface
118 extern void elv_dispatch_sort(struct request_queue *, struct request *);
119 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
120 extern void elv_add_request(struct request_queue *, struct request *, int);
121 extern void __elv_add_request(struct request_queue *, struct request *, int);
122 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
123 extern int elv_try_merge(struct request *, struct bio *);
124 extern void elv_merge_requests(struct request_queue *, struct request *,
126 extern void elv_merged_request(struct request_queue *, struct request *, int);
127 extern void elv_bio_merged(struct request_queue *q, struct request *,
129 extern void elv_requeue_request(struct request_queue *, struct request *);
130 extern struct request *elv_former_request(struct request_queue *, struct request *);
131 extern struct request *elv_latter_request(struct request_queue *, struct request *);
132 extern int elv_register_queue(struct request_queue *q);
133 extern void elv_unregister_queue(struct request_queue *q);
134 extern int elv_may_queue(struct request_queue *, int);
135 extern void elv_abort_queue(struct request_queue *);
136 extern void elv_completed_request(struct request_queue *, struct request *);
137 extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
138 extern void elv_put_request(struct request_queue *, struct request *);
139 extern void elv_drain_elevator(struct request_queue *);
142 * io scheduler registration
144 extern int elv_register(struct elevator_type *);
145 extern void elv_unregister(struct elevator_type *);
148 * io scheduler sysfs switching
150 extern ssize_t elv_iosched_show(struct request_queue *, char *);
151 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
153 extern int elevator_init(struct request_queue *, char *);
154 extern void elevator_exit(struct elevator_queue *);
155 extern int elevator_change(struct request_queue *, const char *);
156 extern int elv_rq_merge_ok(struct request *, struct bio *);
161 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
162 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
165 * rb support functions.
167 extern void elv_rb_add(struct rb_root *, struct request *);
168 extern void elv_rb_del(struct rb_root *, struct request *);
169 extern struct request *elv_rb_find(struct rb_root *, sector_t);
172 * Return values from elevator merger
174 #define ELEVATOR_NO_MERGE 0
175 #define ELEVATOR_FRONT_MERGE 1
176 #define ELEVATOR_BACK_MERGE 2
179 * Insertion selection
181 #define ELEVATOR_INSERT_FRONT 1
182 #define ELEVATOR_INSERT_BACK 2
183 #define ELEVATOR_INSERT_SORT 3
184 #define ELEVATOR_INSERT_REQUEUE 4
185 #define ELEVATOR_INSERT_FLUSH 5
186 #define ELEVATOR_INSERT_SORT_MERGE 6
189 * return values from elevator_may_queue_fn
197 #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
198 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
201 * Hack to reuse the csd.list list_head as the fifo time holder while
202 * the request is in the io scheduler. Saves an unsigned long in rq.
204 #define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
205 #define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
206 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
207 #define rq_fifo_clear(rq) do { \
208 list_del_init(&(rq)->queuelist); \
209 INIT_LIST_HEAD(&(rq)->csd.list); \
212 #endif /* CONFIG_BLOCK */