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
8struct io_cq;
9
10typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
11 struct bio *);
12
13typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
14
15typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
16
17typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
18
19typedef void (elevator_bio_merged_fn) (struct request_queue *,
20 struct request *, struct bio *);
21
22typedef int (elevator_dispatch_fn) (struct request_queue *, int);
23
24typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
25typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
26typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
27typedef int (elevator_may_queue_fn) (struct request_queue *, int);
28
29typedef void (elevator_init_icq_fn) (struct io_cq *);
30typedef void (elevator_exit_icq_fn) (struct io_cq *);
31typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
32typedef void (elevator_put_req_fn) (struct request *);
33typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
34typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
35
36typedef void *(elevator_init_fn) (struct request_queue *);
37typedef void (elevator_exit_fn) (struct elevator_queue *);
38
39struct elevator_ops
40{
41 elevator_merge_fn *elevator_merge_fn;
42 elevator_merged_fn *elevator_merged_fn;
43 elevator_merge_req_fn *elevator_merge_req_fn;
44 elevator_allow_merge_fn *elevator_allow_merge_fn;
45 elevator_bio_merged_fn *elevator_bio_merged_fn;
46
47 elevator_dispatch_fn *elevator_dispatch_fn;
48 elevator_add_req_fn *elevator_add_req_fn;
49 elevator_activate_req_fn *elevator_activate_req_fn;
50 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
51
52 elevator_completed_req_fn *elevator_completed_req_fn;
53
54 elevator_request_list_fn *elevator_former_req_fn;
55 elevator_request_list_fn *elevator_latter_req_fn;
56
57 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
58 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
59
60 elevator_set_req_fn *elevator_set_req_fn;
61 elevator_put_req_fn *elevator_put_req_fn;
62
63 elevator_may_queue_fn *elevator_may_queue_fn;
64
65 elevator_init_fn *elevator_init_fn;
66 elevator_exit_fn *elevator_exit_fn;
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 /* managed by elevator core */
83 struct kmem_cache *icq_cache;
84
85 /* fields provided by elevator implementation */
86 struct elevator_ops ops;
87 size_t icq_size; /* see iocontext.h */
88 size_t icq_align; /* ditto */
89 struct elv_fs_entry *elevator_attrs;
90 char elevator_name[ELV_NAME_MAX];
91 struct module *elevator_owner;
92
93 /* managed by elevator core */
94 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
95 struct list_head list;
96};
97
98/*
99 * each queue has an elevator_queue associated with it
100 */
101struct elevator_queue
102{
103 struct elevator_type *type;
104 void *elevator_data;
105 struct kobject kobj;
106 struct mutex sysfs_lock;
107 struct hlist_head *hash;
108 unsigned int registered:1;
109};
110
111/*
112 * block elevator interface
113 */
114extern void elv_dispatch_sort(struct request_queue *, struct request *);
115extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
116extern void elv_add_request(struct request_queue *, struct request *, int);
117extern void __elv_add_request(struct request_queue *, struct request *, int);
118extern int elv_merge(struct request_queue *, struct request **, struct bio *);
119extern void elv_merge_requests(struct request_queue *, struct request *,
120 struct request *);
121extern void elv_merged_request(struct request_queue *, struct request *, int);
122extern void elv_bio_merged(struct request_queue *q, struct request *,
123 struct bio *);
124extern void elv_requeue_request(struct request_queue *, struct request *);
125extern struct request *elv_former_request(struct request_queue *, struct request *);
126extern struct request *elv_latter_request(struct request_queue *, struct request *);
127extern int elv_register_queue(struct request_queue *q);
128extern void elv_unregister_queue(struct request_queue *q);
129extern int elv_may_queue(struct request_queue *, int);
130extern void elv_abort_queue(struct request_queue *);
131extern void elv_completed_request(struct request_queue *, struct request *);
132extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
133extern void elv_put_request(struct request_queue *, struct request *);
134extern void elv_drain_elevator(struct request_queue *);
135
136/*
137 * io scheduler registration
138 */
139extern int elv_register(struct elevator_type *);
140extern void elv_unregister(struct elevator_type *);
141
142/*
143 * io scheduler sysfs switching
144 */
145extern ssize_t elv_iosched_show(struct request_queue *, char *);
146extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
147
148extern int elevator_init(struct request_queue *, char *);
149extern void elevator_exit(struct elevator_queue *);
150extern int elevator_change(struct request_queue *, const char *);
151extern bool elv_rq_merge_ok(struct request *, struct bio *);
152
153/*
154 * Helper functions.
155 */
156extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
157extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
158
159/*
160 * rb support functions.
161 */
162extern void elv_rb_add(struct rb_root *, struct request *);
163extern void elv_rb_del(struct rb_root *, struct request *);
164extern struct request *elv_rb_find(struct rb_root *, sector_t);
165
166/*
167 * Return values from elevator merger
168 */
169#define ELEVATOR_NO_MERGE 0
170#define ELEVATOR_FRONT_MERGE 1
171#define ELEVATOR_BACK_MERGE 2
172
173/*
174 * Insertion selection
175 */
176#define ELEVATOR_INSERT_FRONT 1
177#define ELEVATOR_INSERT_BACK 2
178#define ELEVATOR_INSERT_SORT 3
179#define ELEVATOR_INSERT_REQUEUE 4
180#define ELEVATOR_INSERT_FLUSH 5
181#define ELEVATOR_INSERT_SORT_MERGE 6
182
183/*
184 * return values from elevator_may_queue_fn
185 */
186enum {
187 ELV_MQUEUE_MAY,
188 ELV_MQUEUE_NO,
189 ELV_MQUEUE_MUST,
190};
191
192#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
193#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
194
195/*
196 * Hack to reuse the csd.list list_head as the fifo time holder while
197 * the request is in the io scheduler. Saves an unsigned long in rq.
198 */
199#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
200#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
201#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
202#define rq_fifo_clear(rq) do { \
203 list_del_init(&(rq)->queuelist); \
204 INIT_LIST_HEAD(&(rq)->csd.list); \
205 } while (0)
206
207#endif /* CONFIG_BLOCK */
208#endif