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;
10
11typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
12 struct bio *);
13
14typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
15
16typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
17
18typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
19
20typedef void (elevator_bio_merged_fn) (struct request_queue *,
21 struct request *, struct bio *);
22
23typedef int (elevator_dispatch_fn) (struct request_queue *, int);
24
25typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
26typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
27typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
28typedef int (elevator_may_queue_fn) (struct request_queue *, int);
29
30typedef void (elevator_init_icq_fn) (struct io_cq *);
31typedef void (elevator_exit_icq_fn) (struct io_cq *);
32typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
33 struct bio *, gfp_t);
34typedef void (elevator_put_req_fn) (struct request *);
35typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
36typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
37
38typedef int (elevator_init_fn) (struct request_queue *);
39typedef void (elevator_exit_fn) (struct elevator_queue *);
40
41struct elevator_ops
42{
43 elevator_merge_fn *elevator_merge_fn;
44 elevator_merged_fn *elevator_merged_fn;
45 elevator_merge_req_fn *elevator_merge_req_fn;
46 elevator_allow_merge_fn *elevator_allow_merge_fn;
47 elevator_bio_merged_fn *elevator_bio_merged_fn;
48
49 elevator_dispatch_fn *elevator_dispatch_fn;
50 elevator_add_req_fn *elevator_add_req_fn;
51 elevator_activate_req_fn *elevator_activate_req_fn;
52 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
53
54 elevator_completed_req_fn *elevator_completed_req_fn;
55
56 elevator_request_list_fn *elevator_former_req_fn;
57 elevator_request_list_fn *elevator_latter_req_fn;
58
59 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
60 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
61
62 elevator_set_req_fn *elevator_set_req_fn;
63 elevator_put_req_fn *elevator_put_req_fn;
64
65 elevator_may_queue_fn *elevator_may_queue_fn;
66
67 elevator_init_fn *elevator_init_fn;
68 elevator_exit_fn *elevator_exit_fn;
69};
70
71#define ELV_NAME_MAX (16)
72
73struct elv_fs_entry {
74 struct attribute attr;
75 ssize_t (*show)(struct elevator_queue *, char *);
76 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
77};
78
79/*
80 * identifies an elevator type, such as AS or deadline
81 */
82struct elevator_type
83{
84 /* managed by elevator core */
85 struct kmem_cache *icq_cache;
86
87 /* fields provided by elevator implementation */
88 struct elevator_ops ops;
89 size_t icq_size; /* see iocontext.h */
90 size_t icq_align; /* ditto */
91 struct elv_fs_entry *elevator_attrs;
92 char elevator_name[ELV_NAME_MAX];
93 struct module *elevator_owner;
94
95 /* managed by elevator core */
96 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
97 struct list_head list;
98};
99
100#define ELV_HASH_BITS 6
101
102/*
103 * each queue has an elevator_queue associated with it
104 */
105struct elevator_queue
106{
107 struct elevator_type *type;
108 void *elevator_data;
109 struct kobject kobj;
110 struct mutex sysfs_lock;
111 unsigned int registered:1;
112 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
113};
114
115/*
116 * block elevator interface
117 */
118extern void elv_dispatch_sort(struct request_queue *, struct request *);
119extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
120extern void elv_add_request(struct request_queue *, struct request *, int);
121extern void __elv_add_request(struct request_queue *, struct request *, int);
122extern int elv_merge(struct request_queue *, struct request **, struct bio *);
123extern void elv_merge_requests(struct request_queue *, struct request *,
124 struct request *);
125extern void elv_merged_request(struct request_queue *, struct request *, int);
126extern void elv_bio_merged(struct request_queue *q, struct request *,
127 struct bio *);
128extern void elv_requeue_request(struct request_queue *, struct request *);
129extern struct request *elv_former_request(struct request_queue *, struct request *);
130extern struct request *elv_latter_request(struct request_queue *, struct request *);
131extern int elv_register_queue(struct request_queue *q);
132extern void elv_unregister_queue(struct request_queue *q);
133extern int elv_may_queue(struct request_queue *, int);
134extern void elv_abort_queue(struct request_queue *);
135extern void elv_completed_request(struct request_queue *, struct request *);
136extern int elv_set_request(struct request_queue *q, struct request *rq,
137 struct bio *bio, gfp_t gfp_mask);
138extern void elv_put_request(struct request_queue *, struct request *);
139extern void elv_drain_elevator(struct request_queue *);
140
141/*
142 * io scheduler registration
143 */
144extern void __init load_default_elevator_module(void);
145extern int elv_register(struct elevator_type *);
146extern void elv_unregister(struct elevator_type *);
147
148/*
149 * io scheduler sysfs switching
150 */
151extern ssize_t elv_iosched_show(struct request_queue *, char *);
152extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
153
154extern int elevator_init(struct request_queue *, char *);
155extern void elevator_exit(struct elevator_queue *);
156extern int elevator_change(struct request_queue *, const char *);
157extern bool elv_rq_merge_ok(struct request *, struct bio *);
158
159/*
160 * Helper functions.
161 */
162extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
163extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
164
165/*
166 * rb support functions.
167 */
168extern void elv_rb_add(struct rb_root *, struct request *);
169extern void elv_rb_del(struct rb_root *, struct request *);
170extern struct request *elv_rb_find(struct rb_root *, sector_t);
171
172/*
173 * Return values from elevator merger
174 */
175#define ELEVATOR_NO_MERGE 0
176#define ELEVATOR_FRONT_MERGE 1
177#define ELEVATOR_BACK_MERGE 2
178
179/*
180 * Insertion selection
181 */
182#define ELEVATOR_INSERT_FRONT 1
183#define ELEVATOR_INSERT_BACK 2
184#define ELEVATOR_INSERT_SORT 3
185#define ELEVATOR_INSERT_REQUEUE 4
186#define ELEVATOR_INSERT_FLUSH 5
187#define ELEVATOR_INSERT_SORT_MERGE 6
188
189/*
190 * return values from elevator_may_queue_fn
191 */
192enum {
193 ELV_MQUEUE_MAY,
194 ELV_MQUEUE_NO,
195 ELV_MQUEUE_MUST,
196};
197
198#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
199#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
200
201/*
202 * Hack to reuse the csd.list list_head as the fifo time holder while
203 * the request is in the io scheduler. Saves an unsigned long in rq.
204 */
205#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
206#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
207#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
208#define rq_fifo_clear(rq) do { \
209 list_del_init(&(rq)->queuelist); \
210 INIT_LIST_HEAD(&(rq)->csd.list); \
211 } while (0)
212
213#else /* CONFIG_BLOCK */
214
215static inline void load_default_elevator_module(void) { }
216
217#endif /* CONFIG_BLOCK */
218#endif