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#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_bio_merge_fn) (struct request_queue *,
20 struct request *, struct bio *);
21
22typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
23 struct request *, struct request *);
24
25typedef void (elevator_bio_merged_fn) (struct request_queue *,
26 struct request *, struct bio *);
27
28typedef int (elevator_dispatch_fn) (struct request_queue *, int);
29
30typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
31typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
32typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
33typedef int (elevator_may_queue_fn) (struct request_queue *, int, int);
34
35typedef void (elevator_init_icq_fn) (struct io_cq *);
36typedef void (elevator_exit_icq_fn) (struct io_cq *);
37typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
38 struct bio *, gfp_t);
39typedef void (elevator_put_req_fn) (struct request *);
40typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
41typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
42
43typedef int (elevator_init_fn) (struct request_queue *,
44 struct elevator_type *e);
45typedef void (elevator_exit_fn) (struct elevator_queue *);
46typedef void (elevator_registered_fn) (struct request_queue *);
47
48struct elevator_ops
49{
50 elevator_merge_fn *elevator_merge_fn;
51 elevator_merged_fn *elevator_merged_fn;
52 elevator_merge_req_fn *elevator_merge_req_fn;
53 elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
54 elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
55 elevator_bio_merged_fn *elevator_bio_merged_fn;
56
57 elevator_dispatch_fn *elevator_dispatch_fn;
58 elevator_add_req_fn *elevator_add_req_fn;
59 elevator_activate_req_fn *elevator_activate_req_fn;
60 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
61
62 elevator_completed_req_fn *elevator_completed_req_fn;
63
64 elevator_request_list_fn *elevator_former_req_fn;
65 elevator_request_list_fn *elevator_latter_req_fn;
66
67 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
68 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
69
70 elevator_set_req_fn *elevator_set_req_fn;
71 elevator_put_req_fn *elevator_put_req_fn;
72
73 elevator_may_queue_fn *elevator_may_queue_fn;
74
75 elevator_init_fn *elevator_init_fn;
76 elevator_exit_fn *elevator_exit_fn;
77 elevator_registered_fn *elevator_registered_fn;
78};
79
80#define ELV_NAME_MAX (16)
81
82struct elv_fs_entry {
83 struct attribute attr;
84 ssize_t (*show)(struct elevator_queue *, char *);
85 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
86};
87
88/*
89 * identifies an elevator type, such as AS or deadline
90 */
91struct elevator_type
92{
93 /* managed by elevator core */
94 struct kmem_cache *icq_cache;
95
96 /* fields provided by elevator implementation */
97 struct elevator_ops ops;
98 size_t icq_size; /* see iocontext.h */
99 size_t icq_align; /* ditto */
100 struct elv_fs_entry *elevator_attrs;
101 char elevator_name[ELV_NAME_MAX];
102 struct module *elevator_owner;
103
104 /* managed by elevator core */
105 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
106 struct list_head list;
107};
108
109#define ELV_HASH_BITS 6
110
111/*
112 * each queue has an elevator_queue associated with it
113 */
114struct elevator_queue
115{
116 struct elevator_type *type;
117 void *elevator_data;
118 struct kobject kobj;
119 struct mutex sysfs_lock;
120 unsigned int registered:1;
121 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
122};
123
124/*
125 * block elevator interface
126 */
127extern void elv_dispatch_sort(struct request_queue *, struct request *);
128extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
129extern void elv_add_request(struct request_queue *, struct request *, int);
130extern void __elv_add_request(struct request_queue *, struct request *, int);
131extern int elv_merge(struct request_queue *, struct request **, struct bio *);
132extern void elv_merge_requests(struct request_queue *, struct request *,
133 struct request *);
134extern void elv_merged_request(struct request_queue *, struct request *, int);
135extern void elv_bio_merged(struct request_queue *q, struct request *,
136 struct bio *);
137extern void elv_requeue_request(struct request_queue *, struct request *);
138extern struct request *elv_former_request(struct request_queue *, struct request *);
139extern struct request *elv_latter_request(struct request_queue *, struct request *);
140extern int elv_register_queue(struct request_queue *q);
141extern void elv_unregister_queue(struct request_queue *q);
142extern int elv_may_queue(struct request_queue *, int, int);
143extern void elv_completed_request(struct request_queue *, struct request *);
144extern int elv_set_request(struct request_queue *q, struct request *rq,
145 struct bio *bio, gfp_t gfp_mask);
146extern void elv_put_request(struct request_queue *, struct request *);
147extern void elv_drain_elevator(struct request_queue *);
148
149/*
150 * io scheduler registration
151 */
152extern void __init load_default_elevator_module(void);
153extern int elv_register(struct elevator_type *);
154extern void elv_unregister(struct elevator_type *);
155
156/*
157 * io scheduler sysfs switching
158 */
159extern ssize_t elv_iosched_show(struct request_queue *, char *);
160extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
161
162extern int elevator_init(struct request_queue *, char *);
163extern void elevator_exit(struct elevator_queue *);
164extern int elevator_change(struct request_queue *, const char *);
165extern bool elv_bio_merge_ok(struct request *, struct bio *);
166extern struct elevator_queue *elevator_alloc(struct request_queue *,
167 struct elevator_type *);
168
169/*
170 * Helper functions.
171 */
172extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
173extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
174
175/*
176 * rb support functions.
177 */
178extern void elv_rb_add(struct rb_root *, struct request *);
179extern void elv_rb_del(struct rb_root *, struct request *);
180extern struct request *elv_rb_find(struct rb_root *, sector_t);
181
182/*
183 * Return values from elevator merger
184 */
185#define ELEVATOR_NO_MERGE 0
186#define ELEVATOR_FRONT_MERGE 1
187#define ELEVATOR_BACK_MERGE 2
188
189/*
190 * Insertion selection
191 */
192#define ELEVATOR_INSERT_FRONT 1
193#define ELEVATOR_INSERT_BACK 2
194#define ELEVATOR_INSERT_SORT 3
195#define ELEVATOR_INSERT_REQUEUE 4
196#define ELEVATOR_INSERT_FLUSH 5
197#define ELEVATOR_INSERT_SORT_MERGE 6
198
199/*
200 * return values from elevator_may_queue_fn
201 */
202enum {
203 ELV_MQUEUE_MAY,
204 ELV_MQUEUE_NO,
205 ELV_MQUEUE_MUST,
206};
207
208#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
209#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
210
211#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
212#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
213
214#else /* CONFIG_BLOCK */
215
216static inline void load_default_elevator_module(void) { }
217
218#endif /* CONFIG_BLOCK */
219#endif