Linux kernel mirror (for testing)
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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 int (elevator_queue_empty_fn) (struct request_queue *);
24typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
25typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
26typedef int (elevator_may_queue_fn) (struct request_queue *, int);
27
28typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
29typedef void (elevator_put_req_fn) (struct request *);
30typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
31typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
32
33typedef void *(elevator_init_fn) (struct request_queue *);
34typedef void (elevator_exit_fn) (struct elevator_queue *);
35
36struct elevator_ops
37{
38 elevator_merge_fn *elevator_merge_fn;
39 elevator_merged_fn *elevator_merged_fn;
40 elevator_merge_req_fn *elevator_merge_req_fn;
41 elevator_allow_merge_fn *elevator_allow_merge_fn;
42 elevator_bio_merged_fn *elevator_bio_merged_fn;
43
44 elevator_dispatch_fn *elevator_dispatch_fn;
45 elevator_add_req_fn *elevator_add_req_fn;
46 elevator_activate_req_fn *elevator_activate_req_fn;
47 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
48
49 elevator_queue_empty_fn *elevator_queue_empty_fn;
50 elevator_completed_req_fn *elevator_completed_req_fn;
51
52 elevator_request_list_fn *elevator_former_req_fn;
53 elevator_request_list_fn *elevator_latter_req_fn;
54
55 elevator_set_req_fn *elevator_set_req_fn;
56 elevator_put_req_fn *elevator_put_req_fn;
57
58 elevator_may_queue_fn *elevator_may_queue_fn;
59
60 elevator_init_fn *elevator_init_fn;
61 elevator_exit_fn *elevator_exit_fn;
62 void (*trim)(struct io_context *);
63};
64
65#define ELV_NAME_MAX (16)
66
67struct elv_fs_entry {
68 struct attribute attr;
69 ssize_t (*show)(struct elevator_queue *, char *);
70 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
71};
72
73/*
74 * identifies an elevator type, such as AS or deadline
75 */
76struct elevator_type
77{
78 struct list_head list;
79 struct elevator_ops ops;
80 struct elv_fs_entry *elevator_attrs;
81 char elevator_name[ELV_NAME_MAX];
82 struct module *elevator_owner;
83};
84
85/*
86 * each queue has an elevator_queue associated with it
87 */
88struct elevator_queue
89{
90 struct elevator_ops *ops;
91 void *elevator_data;
92 struct kobject kobj;
93 struct elevator_type *elevator_type;
94 struct mutex sysfs_lock;
95 struct hlist_head *hash;
96};
97
98/*
99 * block elevator interface
100 */
101extern void elv_dispatch_sort(struct request_queue *, struct request *);
102extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
103extern void elv_add_request(struct request_queue *, struct request *, int, int);
104extern void __elv_add_request(struct request_queue *, struct request *, int, int);
105extern void elv_insert(struct request_queue *, struct request *, int);
106extern int elv_merge(struct request_queue *, struct request **, struct bio *);
107extern void elv_merge_requests(struct request_queue *, struct request *,
108 struct request *);
109extern void elv_merged_request(struct request_queue *, struct request *, int);
110extern void elv_bio_merged(struct request_queue *q, struct request *,
111 struct bio *);
112extern void elv_requeue_request(struct request_queue *, struct request *);
113extern int elv_queue_empty(struct request_queue *);
114extern struct request *elv_former_request(struct request_queue *, struct request *);
115extern struct request *elv_latter_request(struct request_queue *, struct request *);
116extern int elv_register_queue(struct request_queue *q);
117extern void elv_unregister_queue(struct request_queue *q);
118extern int elv_may_queue(struct request_queue *, int);
119extern void elv_abort_queue(struct request_queue *);
120extern void elv_completed_request(struct request_queue *, struct request *);
121extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
122extern void elv_put_request(struct request_queue *, struct request *);
123extern void elv_drain_elevator(struct request_queue *);
124
125/*
126 * io scheduler registration
127 */
128extern void elv_register(struct elevator_type *);
129extern void elv_unregister(struct elevator_type *);
130
131/*
132 * io scheduler sysfs switching
133 */
134extern ssize_t elv_iosched_show(struct request_queue *, char *);
135extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
136
137extern int elevator_init(struct request_queue *, char *);
138extern void elevator_exit(struct elevator_queue *);
139extern int elevator_change(struct request_queue *, const char *);
140extern int elv_rq_merge_ok(struct request *, struct bio *);
141
142/*
143 * Helper functions.
144 */
145extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
146extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
147
148/*
149 * rb support functions.
150 */
151extern struct request *elv_rb_add(struct rb_root *, struct request *);
152extern void elv_rb_del(struct rb_root *, struct request *);
153extern struct request *elv_rb_find(struct rb_root *, sector_t);
154
155/*
156 * Return values from elevator merger
157 */
158#define ELEVATOR_NO_MERGE 0
159#define ELEVATOR_FRONT_MERGE 1
160#define ELEVATOR_BACK_MERGE 2
161
162/*
163 * Insertion selection
164 */
165#define ELEVATOR_INSERT_FRONT 1
166#define ELEVATOR_INSERT_BACK 2
167#define ELEVATOR_INSERT_SORT 3
168#define ELEVATOR_INSERT_REQUEUE 4
169
170/*
171 * return values from elevator_may_queue_fn
172 */
173enum {
174 ELV_MQUEUE_MAY,
175 ELV_MQUEUE_NO,
176 ELV_MQUEUE_MUST,
177};
178
179#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
180#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
181
182/*
183 * Hack to reuse the csd.list list_head as the fifo time holder while
184 * the request is in the io scheduler. Saves an unsigned long in rq.
185 */
186#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
187#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
188#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
189#define rq_fifo_clear(rq) do { \
190 list_del_init(&(rq)->queuelist); \
191 INIT_LIST_HEAD(&(rq)->csd.list); \
192 } while (0)
193
194/*
195 * io context count accounting
196 */
197#define elv_ioc_count_mod(name, __val) \
198 do { \
199 preempt_disable(); \
200 __get_cpu_var(name) += (__val); \
201 preempt_enable(); \
202 } while (0)
203
204#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
205#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
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