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1#ifndef _LINUX_ELEVATOR_H
2#define _LINUX_ELEVATOR_H
3
4#include <linux/percpu.h>
5
6#ifdef CONFIG_BLOCK
7
8typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
9 struct bio *);
10
11typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
12
13typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
14
15typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
16
17typedef void (elevator_bio_merged_fn) (struct request_queue *,
18 struct request *, struct bio *);
19
20typedef int (elevator_dispatch_fn) (struct request_queue *, int);
21
22typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
23typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
24typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
25typedef int (elevator_may_queue_fn) (struct request_queue *, int);
26
27typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
28typedef void (elevator_put_req_fn) (struct request *);
29typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
30typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
31
32typedef void *(elevator_init_fn) (struct request_queue *);
33typedef void (elevator_exit_fn) (struct elevator_queue *);
34
35struct elevator_ops
36{
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;
41
42 /*
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.
46 */
47 elevator_bio_merged_fn *elevator_bio_merged_fn;
48
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;
53
54 elevator_completed_req_fn *elevator_completed_req_fn;
55
56 elevator_request_list_fn *elevator_former_req_fn;
57 elevator_request_list_fn *elevator_latter_req_fn;
58
59 elevator_set_req_fn *elevator_set_req_fn;
60 elevator_put_req_fn *elevator_put_req_fn;
61
62 elevator_may_queue_fn *elevator_may_queue_fn;
63
64 elevator_init_fn *elevator_init_fn;
65 elevator_exit_fn *elevator_exit_fn;
66 void (*trim)(struct io_context *);
67};
68
69#define ELV_NAME_MAX (16)
70
71struct elv_fs_entry {
72 struct attribute attr;
73 ssize_t (*show)(struct elevator_queue *, char *);
74 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
75};
76
77/*
78 * identifies an elevator type, such as AS or deadline
79 */
80struct elevator_type
81{
82 struct list_head list;
83 struct elevator_ops ops;
84 struct elv_fs_entry *elevator_attrs;
85 char elevator_name[ELV_NAME_MAX];
86 struct module *elevator_owner;
87};
88
89/*
90 * each queue has an elevator_queue associated with it
91 */
92struct elevator_queue
93{
94 struct elevator_ops *ops;
95 void *elevator_data;
96 struct kobject kobj;
97 struct elevator_type *elevator_type;
98 struct mutex sysfs_lock;
99 struct hlist_head *hash;
100 unsigned int registered:1;
101};
102
103/*
104 * block elevator interface
105 */
106extern void elv_dispatch_sort(struct request_queue *, struct request *);
107extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
108extern void elv_add_request(struct request_queue *, struct request *, int);
109extern void __elv_add_request(struct request_queue *, struct request *, int);
110extern int elv_merge(struct request_queue *, struct request **, struct bio *);
111extern int elv_try_merge(struct request *, struct bio *);
112extern void elv_merge_requests(struct request_queue *, struct request *,
113 struct request *);
114extern void elv_merged_request(struct request_queue *, struct request *, int);
115extern void elv_bio_merged(struct request_queue *q, struct request *,
116 struct bio *);
117extern void elv_requeue_request(struct request_queue *, struct request *);
118extern struct request *elv_former_request(struct request_queue *, struct request *);
119extern struct request *elv_latter_request(struct request_queue *, struct request *);
120extern int elv_register_queue(struct request_queue *q);
121extern void elv_unregister_queue(struct request_queue *q);
122extern int elv_may_queue(struct request_queue *, int);
123extern void elv_abort_queue(struct request_queue *);
124extern void elv_completed_request(struct request_queue *, struct request *);
125extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
126extern void elv_put_request(struct request_queue *, struct request *);
127extern void elv_drain_elevator(struct request_queue *);
128
129/*
130 * io scheduler registration
131 */
132extern void elv_register(struct elevator_type *);
133extern void elv_unregister(struct elevator_type *);
134
135/*
136 * io scheduler sysfs switching
137 */
138extern ssize_t elv_iosched_show(struct request_queue *, char *);
139extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
140
141extern int elevator_init(struct request_queue *, char *);
142extern void elevator_exit(struct elevator_queue *);
143extern int elevator_change(struct request_queue *, const char *);
144extern int elv_rq_merge_ok(struct request *, struct bio *);
145
146/*
147 * Helper functions.
148 */
149extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
150extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
151
152/*
153 * rb support functions.
154 */
155extern void elv_rb_add(struct rb_root *, struct request *);
156extern void elv_rb_del(struct rb_root *, struct request *);
157extern struct request *elv_rb_find(struct rb_root *, sector_t);
158
159/*
160 * Return values from elevator merger
161 */
162#define ELEVATOR_NO_MERGE 0
163#define ELEVATOR_FRONT_MERGE 1
164#define ELEVATOR_BACK_MERGE 2
165
166/*
167 * Insertion selection
168 */
169#define ELEVATOR_INSERT_FRONT 1
170#define ELEVATOR_INSERT_BACK 2
171#define ELEVATOR_INSERT_SORT 3
172#define ELEVATOR_INSERT_REQUEUE 4
173#define ELEVATOR_INSERT_FLUSH 5
174#define ELEVATOR_INSERT_SORT_MERGE 6
175
176/*
177 * return values from elevator_may_queue_fn
178 */
179enum {
180 ELV_MQUEUE_MAY,
181 ELV_MQUEUE_NO,
182 ELV_MQUEUE_MUST,
183};
184
185#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
186#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
187
188/*
189 * Hack to reuse the csd.list list_head as the fifo time holder while
190 * the request is in the io scheduler. Saves an unsigned long in rq.
191 */
192#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
193#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
194#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
195#define rq_fifo_clear(rq) do { \
196 list_del_init(&(rq)->queuelist); \
197 INIT_LIST_HEAD(&(rq)->csd.list); \
198 } while (0)
199
200/*
201 * io context count accounting
202 */
203#define elv_ioc_count_mod(name, __val) this_cpu_add(name, __val)
204#define elv_ioc_count_inc(name) this_cpu_inc(name)
205#define elv_ioc_count_dec(name) this_cpu_dec(name)
206
207#define elv_ioc_count_read(name) \
208({ \
209 unsigned long __val = 0; \
210 int __cpu; \
211 smp_wmb(); \
212 for_each_possible_cpu(__cpu) \
213 __val += per_cpu(name, __cpu); \
214 __val; \
215})
216
217#endif /* CONFIG_BLOCK */
218#endif