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 *,
32 struct bio *, gfp_t);
33typedef void (elevator_put_req_fn) (struct request *);
34typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
35typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
36
37typedef int (elevator_init_fn) (struct request_queue *);
38typedef void (elevator_exit_fn) (struct elevator_queue *);
39
40struct elevator_ops
41{
42 elevator_merge_fn *elevator_merge_fn;
43 elevator_merged_fn *elevator_merged_fn;
44 elevator_merge_req_fn *elevator_merge_req_fn;
45 elevator_allow_merge_fn *elevator_allow_merge_fn;
46 elevator_bio_merged_fn *elevator_bio_merged_fn;
47
48 elevator_dispatch_fn *elevator_dispatch_fn;
49 elevator_add_req_fn *elevator_add_req_fn;
50 elevator_activate_req_fn *elevator_activate_req_fn;
51 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
52
53 elevator_completed_req_fn *elevator_completed_req_fn;
54
55 elevator_request_list_fn *elevator_former_req_fn;
56 elevator_request_list_fn *elevator_latter_req_fn;
57
58 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
59 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
60
61 elevator_set_req_fn *elevator_set_req_fn;
62 elevator_put_req_fn *elevator_put_req_fn;
63
64 elevator_may_queue_fn *elevator_may_queue_fn;
65
66 elevator_init_fn *elevator_init_fn;
67 elevator_exit_fn *elevator_exit_fn;
68};
69
70#define ELV_NAME_MAX (16)
71
72struct elv_fs_entry {
73 struct attribute attr;
74 ssize_t (*show)(struct elevator_queue *, char *);
75 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
76};
77
78/*
79 * identifies an elevator type, such as AS or deadline
80 */
81struct elevator_type
82{
83 /* managed by elevator core */
84 struct kmem_cache *icq_cache;
85
86 /* fields provided by elevator implementation */
87 struct elevator_ops ops;
88 size_t icq_size; /* see iocontext.h */
89 size_t icq_align; /* ditto */
90 struct elv_fs_entry *elevator_attrs;
91 char elevator_name[ELV_NAME_MAX];
92 struct module *elevator_owner;
93
94 /* managed by elevator core */
95 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
96 struct list_head list;
97};
98
99/*
100 * each queue has an elevator_queue associated with it
101 */
102struct elevator_queue
103{
104 struct elevator_type *type;
105 void *elevator_data;
106 struct kobject kobj;
107 struct mutex sysfs_lock;
108 struct hlist_head *hash;
109 unsigned int registered:1;
110};
111
112/*
113 * block elevator interface
114 */
115extern void elv_dispatch_sort(struct request_queue *, struct request *);
116extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
117extern void elv_add_request(struct request_queue *, struct request *, int);
118extern void __elv_add_request(struct request_queue *, struct request *, int);
119extern int elv_merge(struct request_queue *, struct request **, struct bio *);
120extern void elv_merge_requests(struct request_queue *, struct request *,
121 struct request *);
122extern void elv_merged_request(struct request_queue *, struct request *, int);
123extern void elv_bio_merged(struct request_queue *q, struct request *,
124 struct bio *);
125extern void elv_requeue_request(struct request_queue *, struct request *);
126extern struct request *elv_former_request(struct request_queue *, struct request *);
127extern struct request *elv_latter_request(struct request_queue *, struct request *);
128extern int elv_register_queue(struct request_queue *q);
129extern void elv_unregister_queue(struct request_queue *q);
130extern int elv_may_queue(struct request_queue *, int);
131extern void elv_abort_queue(struct request_queue *);
132extern void elv_completed_request(struct request_queue *, struct request *);
133extern int elv_set_request(struct request_queue *q, struct request *rq,
134 struct bio *bio, gfp_t gfp_mask);
135extern void elv_put_request(struct request_queue *, struct request *);
136extern void elv_drain_elevator(struct request_queue *);
137
138/*
139 * io scheduler registration
140 */
141extern int elv_register(struct elevator_type *);
142extern void elv_unregister(struct elevator_type *);
143
144/*
145 * io scheduler sysfs switching
146 */
147extern ssize_t elv_iosched_show(struct request_queue *, char *);
148extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
149
150extern int elevator_init(struct request_queue *, char *);
151extern void elevator_exit(struct elevator_queue *);
152extern int elevator_change(struct request_queue *, const char *);
153extern bool elv_rq_merge_ok(struct request *, struct bio *);
154
155/*
156 * Helper functions.
157 */
158extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
159extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
160
161/*
162 * rb support functions.
163 */
164extern void elv_rb_add(struct rb_root *, struct request *);
165extern void elv_rb_del(struct rb_root *, struct request *);
166extern struct request *elv_rb_find(struct rb_root *, sector_t);
167
168/*
169 * Return values from elevator merger
170 */
171#define ELEVATOR_NO_MERGE 0
172#define ELEVATOR_FRONT_MERGE 1
173#define ELEVATOR_BACK_MERGE 2
174
175/*
176 * Insertion selection
177 */
178#define ELEVATOR_INSERT_FRONT 1
179#define ELEVATOR_INSERT_BACK 2
180#define ELEVATOR_INSERT_SORT 3
181#define ELEVATOR_INSERT_REQUEUE 4
182#define ELEVATOR_INSERT_FLUSH 5
183#define ELEVATOR_INSERT_SORT_MERGE 6
184
185/*
186 * return values from elevator_may_queue_fn
187 */
188enum {
189 ELV_MQUEUE_MAY,
190 ELV_MQUEUE_NO,
191 ELV_MQUEUE_MUST,
192};
193
194#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
195#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
196
197/*
198 * Hack to reuse the csd.list list_head as the fifo time holder while
199 * the request is in the io scheduler. Saves an unsigned long in rq.
200 */
201#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
202#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
203#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
204#define rq_fifo_clear(rq) do { \
205 list_del_init(&(rq)->queuelist); \
206 INIT_LIST_HEAD(&(rq)->csd.list); \
207 } while (0)
208
209#endif /* CONFIG_BLOCK */
210#endif