1 #ifndef _LINUX_ELEVATOR_H
2 #define _LINUX_ELEVATOR_H
4 #include <linux/percpu.h>
8 typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
11 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
13 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
15 typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
17 typedef void (elevator_bio_merged_fn) (struct request_queue *,
18 struct request *, struct bio *);
20 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
22 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
23 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
24 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
25 typedef int (elevator_may_queue_fn) (struct request_queue *, int);
27 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
28 typedef void (elevator_put_req_fn) (struct request *);
29 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
30 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
32 typedef void *(elevator_init_fn) (struct request_queue *);
33 typedef void (elevator_exit_fn) (struct elevator_queue *);
37 elevator_merge_fn *elevator_merge_fn;
38 elevator_merged_fn *elevator_merged_fn;
39 elevator_merge_req_fn *elevator_merge_req_fn;
40 elevator_allow_merge_fn *elevator_allow_merge_fn;
43 * Used for both plugged list and elevator merging and in the
44 * former case called without queue_lock. Read comment on top of
45 * attempt_plug_merge() for details.
47 elevator_bio_merged_fn *elevator_bio_merged_fn;
49 elevator_dispatch_fn *elevator_dispatch_fn;
50 elevator_add_req_fn *elevator_add_req_fn;
51 elevator_activate_req_fn *elevator_activate_req_fn;
52 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
54 elevator_completed_req_fn *elevator_completed_req_fn;
56 elevator_request_list_fn *elevator_former_req_fn;
57 elevator_request_list_fn *elevator_latter_req_fn;
59 elevator_set_req_fn *elevator_set_req_fn;
60 elevator_put_req_fn *elevator_put_req_fn;
62 elevator_may_queue_fn *elevator_may_queue_fn;
64 elevator_init_fn *elevator_init_fn;
65 elevator_exit_fn *elevator_exit_fn;
68 #define ELV_NAME_MAX (16)
71 struct attribute attr;
72 ssize_t (*show)(struct elevator_queue *, char *);
73 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
77 * identifies an elevator type, such as AS or deadline
81 struct list_head list;
82 struct elevator_ops ops;
83 struct elv_fs_entry *elevator_attrs;
84 char elevator_name[ELV_NAME_MAX];
85 struct module *elevator_owner;
89 * each queue has an elevator_queue associated with it
93 struct elevator_ops *ops;
96 struct elevator_type *elevator_type;
97 struct mutex sysfs_lock;
98 struct hlist_head *hash;
99 unsigned int registered:1;
103 * block elevator interface
105 extern void elv_dispatch_sort(struct request_queue *, struct request *);
106 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
107 extern void elv_add_request(struct request_queue *, struct request *, int);
108 extern void __elv_add_request(struct request_queue *, struct request *, int);
109 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
110 extern int elv_try_merge(struct request *, struct bio *);
111 extern void elv_merge_requests(struct request_queue *, struct request *,
113 extern void elv_merged_request(struct request_queue *, struct request *, int);
114 extern void elv_bio_merged(struct request_queue *q, struct request *,
116 extern void elv_requeue_request(struct request_queue *, struct request *);
117 extern struct request *elv_former_request(struct request_queue *, struct request *);
118 extern struct request *elv_latter_request(struct request_queue *, struct request *);
119 extern int elv_register_queue(struct request_queue *q);
120 extern void elv_unregister_queue(struct request_queue *q);
121 extern int elv_may_queue(struct request_queue *, int);
122 extern void elv_abort_queue(struct request_queue *);
123 extern void elv_completed_request(struct request_queue *, struct request *);
124 extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
125 extern void elv_put_request(struct request_queue *, struct request *);
126 extern void elv_drain_elevator(struct request_queue *);
129 * io scheduler registration
131 extern void elv_register(struct elevator_type *);
132 extern void elv_unregister(struct elevator_type *);
135 * io scheduler sysfs switching
137 extern ssize_t elv_iosched_show(struct request_queue *, char *);
138 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
140 extern int elevator_init(struct request_queue *, char *);
141 extern void elevator_exit(struct elevator_queue *);
142 extern int elevator_change(struct request_queue *, const char *);
143 extern int elv_rq_merge_ok(struct request *, struct bio *);
148 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
149 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
152 * rb support functions.
154 extern void elv_rb_add(struct rb_root *, struct request *);
155 extern void elv_rb_del(struct rb_root *, struct request *);
156 extern struct request *elv_rb_find(struct rb_root *, sector_t);
159 * Return values from elevator merger
161 #define ELEVATOR_NO_MERGE 0
162 #define ELEVATOR_FRONT_MERGE 1
163 #define ELEVATOR_BACK_MERGE 2
166 * Insertion selection
168 #define ELEVATOR_INSERT_FRONT 1
169 #define ELEVATOR_INSERT_BACK 2
170 #define ELEVATOR_INSERT_SORT 3
171 #define ELEVATOR_INSERT_REQUEUE 4
172 #define ELEVATOR_INSERT_FLUSH 5
173 #define ELEVATOR_INSERT_SORT_MERGE 6
176 * return values from elevator_may_queue_fn
184 #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
185 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
188 * Hack to reuse the csd.list list_head as the fifo time holder while
189 * the request is in the io scheduler. Saves an unsigned long in rq.
191 #define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
192 #define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
193 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
194 #define rq_fifo_clear(rq) do { \
195 list_del_init(&(rq)->queuelist); \
196 INIT_LIST_HEAD(&(rq)->csd.list); \
199 #endif /* CONFIG_BLOCK */