Linux kernel mirror (for testing)
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linux
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) (request_queue_t *, struct request **,
9 struct bio *);
10
11typedef void (elevator_merge_req_fn) (request_queue_t *, struct request *, struct request *);
12
13typedef void (elevator_merged_fn) (request_queue_t *, struct request *, int);
14
15typedef int (elevator_dispatch_fn) (request_queue_t *, int);
16
17typedef void (elevator_add_req_fn) (request_queue_t *, struct request *);
18typedef int (elevator_queue_empty_fn) (request_queue_t *);
19typedef struct request *(elevator_request_list_fn) (request_queue_t *, struct request *);
20typedef void (elevator_completed_req_fn) (request_queue_t *, struct request *);
21typedef int (elevator_may_queue_fn) (request_queue_t *, int);
22
23typedef int (elevator_set_req_fn) (request_queue_t *, struct request *, gfp_t);
24typedef void (elevator_put_req_fn) (request_queue_t *, struct request *);
25typedef void (elevator_activate_req_fn) (request_queue_t *, struct request *);
26typedef void (elevator_deactivate_req_fn) (request_queue_t *, struct request *);
27
28typedef void *(elevator_init_fn) (request_queue_t *, elevator_t *);
29typedef void (elevator_exit_fn) (elevator_t *);
30
31struct elevator_ops
32{
33 elevator_merge_fn *elevator_merge_fn;
34 elevator_merged_fn *elevator_merged_fn;
35 elevator_merge_req_fn *elevator_merge_req_fn;
36
37 elevator_dispatch_fn *elevator_dispatch_fn;
38 elevator_add_req_fn *elevator_add_req_fn;
39 elevator_activate_req_fn *elevator_activate_req_fn;
40 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
41
42 elevator_queue_empty_fn *elevator_queue_empty_fn;
43 elevator_completed_req_fn *elevator_completed_req_fn;
44
45 elevator_request_list_fn *elevator_former_req_fn;
46 elevator_request_list_fn *elevator_latter_req_fn;
47
48 elevator_set_req_fn *elevator_set_req_fn;
49 elevator_put_req_fn *elevator_put_req_fn;
50
51 elevator_may_queue_fn *elevator_may_queue_fn;
52
53 elevator_init_fn *elevator_init_fn;
54 elevator_exit_fn *elevator_exit_fn;
55 void (*trim)(struct io_context *);
56};
57
58#define ELV_NAME_MAX (16)
59
60struct elv_fs_entry {
61 struct attribute attr;
62 ssize_t (*show)(elevator_t *, char *);
63 ssize_t (*store)(elevator_t *, const char *, size_t);
64};
65
66/*
67 * identifies an elevator type, such as AS or deadline
68 */
69struct elevator_type
70{
71 struct list_head list;
72 struct elevator_ops ops;
73 struct elv_fs_entry *elevator_attrs;
74 char elevator_name[ELV_NAME_MAX];
75 struct module *elevator_owner;
76};
77
78/*
79 * each queue has an elevator_queue associated with it
80 */
81struct elevator_queue
82{
83 struct elevator_ops *ops;
84 void *elevator_data;
85 struct kobject kobj;
86 struct elevator_type *elevator_type;
87 struct mutex sysfs_lock;
88 struct hlist_head *hash;
89};
90
91/*
92 * block elevator interface
93 */
94extern void elv_dispatch_sort(request_queue_t *, struct request *);
95extern void elv_dispatch_add_tail(request_queue_t *, struct request *);
96extern void elv_add_request(request_queue_t *, struct request *, int, int);
97extern void __elv_add_request(request_queue_t *, struct request *, int, int);
98extern void elv_insert(request_queue_t *, struct request *, int);
99extern int elv_merge(request_queue_t *, struct request **, struct bio *);
100extern void elv_merge_requests(request_queue_t *, struct request *,
101 struct request *);
102extern void elv_merged_request(request_queue_t *, struct request *, int);
103extern void elv_dequeue_request(request_queue_t *, struct request *);
104extern void elv_requeue_request(request_queue_t *, struct request *);
105extern int elv_queue_empty(request_queue_t *);
106extern struct request *elv_next_request(struct request_queue *q);
107extern struct request *elv_former_request(request_queue_t *, struct request *);
108extern struct request *elv_latter_request(request_queue_t *, struct request *);
109extern int elv_register_queue(request_queue_t *q);
110extern void elv_unregister_queue(request_queue_t *q);
111extern int elv_may_queue(request_queue_t *, int);
112extern void elv_completed_request(request_queue_t *, struct request *);
113extern int elv_set_request(request_queue_t *, struct request *, gfp_t);
114extern void elv_put_request(request_queue_t *, struct request *);
115
116/*
117 * io scheduler registration
118 */
119extern int elv_register(struct elevator_type *);
120extern void elv_unregister(struct elevator_type *);
121
122/*
123 * io scheduler sysfs switching
124 */
125extern ssize_t elv_iosched_show(request_queue_t *, char *);
126extern ssize_t elv_iosched_store(request_queue_t *, const char *, size_t);
127
128extern int elevator_init(request_queue_t *, char *);
129extern void elevator_exit(elevator_t *);
130extern int elv_rq_merge_ok(struct request *, struct bio *);
131
132/*
133 * Helper functions.
134 */
135extern struct request *elv_rb_former_request(request_queue_t *, struct request *);
136extern struct request *elv_rb_latter_request(request_queue_t *, struct request *);
137
138/*
139 * rb support functions.
140 */
141extern struct request *elv_rb_add(struct rb_root *, struct request *);
142extern void elv_rb_del(struct rb_root *, struct request *);
143extern struct request *elv_rb_find(struct rb_root *, sector_t);
144
145/*
146 * Return values from elevator merger
147 */
148#define ELEVATOR_NO_MERGE 0
149#define ELEVATOR_FRONT_MERGE 1
150#define ELEVATOR_BACK_MERGE 2
151
152/*
153 * Insertion selection
154 */
155#define ELEVATOR_INSERT_FRONT 1
156#define ELEVATOR_INSERT_BACK 2
157#define ELEVATOR_INSERT_SORT 3
158#define ELEVATOR_INSERT_REQUEUE 4
159
160/*
161 * return values from elevator_may_queue_fn
162 */
163enum {
164 ELV_MQUEUE_MAY,
165 ELV_MQUEUE_NO,
166 ELV_MQUEUE_MUST,
167};
168
169#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
170#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
171
172/*
173 * Hack to reuse the donelist list_head as the fifo time holder while
174 * the request is in the io scheduler. Saves an unsigned long in rq.
175 */
176#define rq_fifo_time(rq) ((unsigned long) (rq)->donelist.next)
177#define rq_set_fifo_time(rq,exp) ((rq)->donelist.next = (void *) (exp))
178#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
179#define rq_fifo_clear(rq) do { \
180 list_del_init(&(rq)->queuelist); \
181 INIT_LIST_HEAD(&(rq)->donelist); \
182 } while (0)
183
184/*
185 * io context count accounting
186 */
187#define elv_ioc_count_mod(name, __val) \
188 do { \
189 preempt_disable(); \
190 __get_cpu_var(name) += (__val); \
191 preempt_enable(); \
192 } while (0)
193
194#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
195#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
196
197#define elv_ioc_count_read(name) \
198({ \
199 unsigned long __val = 0; \
200 int __cpu; \
201 smp_wmb(); \
202 for_each_possible_cpu(__cpu) \
203 __val += per_cpu(name, __cpu); \
204 __val; \
205})
206
207#endif /* CONFIG_BLOCK */
208#endif