Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1#ifndef _LINUX_ELEVATOR_H
2#define _LINUX_ELEVATOR_H
3
4#include <linux/percpu.h>
5#include <linux/hashtable.h>
6
7#ifdef CONFIG_BLOCK
8
9struct io_cq;
10struct elevator_type;
11
12typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
13 struct bio *);
14
15typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
16
17typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
18
19typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
20
21typedef void (elevator_bio_merged_fn) (struct request_queue *,
22 struct request *, struct bio *);
23
24typedef int (elevator_dispatch_fn) (struct request_queue *, int);
25
26typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
27typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
28typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
29typedef int (elevator_may_queue_fn) (struct request_queue *, int);
30
31typedef void (elevator_init_icq_fn) (struct io_cq *);
32typedef void (elevator_exit_icq_fn) (struct io_cq *);
33typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
34 struct bio *, gfp_t);
35typedef void (elevator_put_req_fn) (struct request *);
36typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
37typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
38
39typedef int (elevator_init_fn) (struct request_queue *,
40 struct elevator_type *e);
41typedef void (elevator_exit_fn) (struct elevator_queue *);
42
43struct elevator_ops
44{
45 elevator_merge_fn *elevator_merge_fn;
46 elevator_merged_fn *elevator_merged_fn;
47 elevator_merge_req_fn *elevator_merge_req_fn;
48 elevator_allow_merge_fn *elevator_allow_merge_fn;
49 elevator_bio_merged_fn *elevator_bio_merged_fn;
50
51 elevator_dispatch_fn *elevator_dispatch_fn;
52 elevator_add_req_fn *elevator_add_req_fn;
53 elevator_activate_req_fn *elevator_activate_req_fn;
54 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
55
56 elevator_completed_req_fn *elevator_completed_req_fn;
57
58 elevator_request_list_fn *elevator_former_req_fn;
59 elevator_request_list_fn *elevator_latter_req_fn;
60
61 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
62 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
63
64 elevator_set_req_fn *elevator_set_req_fn;
65 elevator_put_req_fn *elevator_put_req_fn;
66
67 elevator_may_queue_fn *elevator_may_queue_fn;
68
69 elevator_init_fn *elevator_init_fn;
70 elevator_exit_fn *elevator_exit_fn;
71};
72
73#define ELV_NAME_MAX (16)
74
75struct elv_fs_entry {
76 struct attribute attr;
77 ssize_t (*show)(struct elevator_queue *, char *);
78 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
79};
80
81/*
82 * identifies an elevator type, such as AS or deadline
83 */
84struct elevator_type
85{
86 /* managed by elevator core */
87 struct kmem_cache *icq_cache;
88
89 /* fields provided by elevator implementation */
90 struct elevator_ops ops;
91 size_t icq_size; /* see iocontext.h */
92 size_t icq_align; /* ditto */
93 struct elv_fs_entry *elevator_attrs;
94 char elevator_name[ELV_NAME_MAX];
95 struct module *elevator_owner;
96
97 /* managed by elevator core */
98 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
99 struct list_head list;
100};
101
102#define ELV_HASH_BITS 6
103
104/*
105 * each queue has an elevator_queue associated with it
106 */
107struct elevator_queue
108{
109 struct elevator_type *type;
110 void *elevator_data;
111 struct kobject kobj;
112 struct mutex sysfs_lock;
113 unsigned int registered:1;
114 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
115};
116
117/*
118 * block elevator interface
119 */
120extern void elv_dispatch_sort(struct request_queue *, struct request *);
121extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
122extern void elv_add_request(struct request_queue *, struct request *, int);
123extern void __elv_add_request(struct request_queue *, struct request *, int);
124extern int elv_merge(struct request_queue *, struct request **, struct bio *);
125extern void elv_merge_requests(struct request_queue *, struct request *,
126 struct request *);
127extern void elv_merged_request(struct request_queue *, struct request *, int);
128extern void elv_bio_merged(struct request_queue *q, struct request *,
129 struct bio *);
130extern void elv_requeue_request(struct request_queue *, struct request *);
131extern struct request *elv_former_request(struct request_queue *, struct request *);
132extern struct request *elv_latter_request(struct request_queue *, struct request *);
133extern int elv_register_queue(struct request_queue *q);
134extern void elv_unregister_queue(struct request_queue *q);
135extern int elv_may_queue(struct request_queue *, int);
136extern void elv_abort_queue(struct request_queue *);
137extern void elv_completed_request(struct request_queue *, struct request *);
138extern int elv_set_request(struct request_queue *q, struct request *rq,
139 struct bio *bio, gfp_t gfp_mask);
140extern void elv_put_request(struct request_queue *, struct request *);
141extern void elv_drain_elevator(struct request_queue *);
142
143/*
144 * io scheduler registration
145 */
146extern void __init load_default_elevator_module(void);
147extern int elv_register(struct elevator_type *);
148extern void elv_unregister(struct elevator_type *);
149
150/*
151 * io scheduler sysfs switching
152 */
153extern ssize_t elv_iosched_show(struct request_queue *, char *);
154extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
155
156extern int elevator_init(struct request_queue *, char *);
157extern void elevator_exit(struct elevator_queue *);
158extern int elevator_change(struct request_queue *, const char *);
159extern bool elv_rq_merge_ok(struct request *, struct bio *);
160extern struct elevator_queue *elevator_alloc(struct request_queue *,
161 struct elevator_type *);
162
163/*
164 * Helper functions.
165 */
166extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
167extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
168
169/*
170 * rb support functions.
171 */
172extern void elv_rb_add(struct rb_root *, struct request *);
173extern void elv_rb_del(struct rb_root *, struct request *);
174extern struct request *elv_rb_find(struct rb_root *, sector_t);
175
176/*
177 * Return values from elevator merger
178 */
179#define ELEVATOR_NO_MERGE 0
180#define ELEVATOR_FRONT_MERGE 1
181#define ELEVATOR_BACK_MERGE 2
182
183/*
184 * Insertion selection
185 */
186#define ELEVATOR_INSERT_FRONT 1
187#define ELEVATOR_INSERT_BACK 2
188#define ELEVATOR_INSERT_SORT 3
189#define ELEVATOR_INSERT_REQUEUE 4
190#define ELEVATOR_INSERT_FLUSH 5
191#define ELEVATOR_INSERT_SORT_MERGE 6
192
193/*
194 * return values from elevator_may_queue_fn
195 */
196enum {
197 ELV_MQUEUE_MAY,
198 ELV_MQUEUE_NO,
199 ELV_MQUEUE_MUST,
200};
201
202#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
203#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
204
205#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
206#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
207
208#else /* CONFIG_BLOCK */
209
210static inline void load_default_elevator_module(void) { }
211
212#endif /* CONFIG_BLOCK */
213#endif