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