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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 *, gfp_t);
32typedef void (elevator_put_req_fn) (struct request *);
33typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
34typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
35
36typedef void *(elevator_init_fn) (struct request_queue *);
37typedef void (elevator_exit_fn) (struct elevator_queue *);
38
39struct elevator_ops
40{
41 elevator_merge_fn *elevator_merge_fn;
42 elevator_merged_fn *elevator_merged_fn;
43 elevator_merge_req_fn *elevator_merge_req_fn;
44 elevator_allow_merge_fn *elevator_allow_merge_fn;
45
46 /*
47 * Used for both plugged list and elevator merging and in the
48 * former case called without queue_lock. Read comment on top of
49 * attempt_plug_merge() for details.
50 */
51 elevator_bio_merged_fn *elevator_bio_merged_fn;
52
53 elevator_dispatch_fn *elevator_dispatch_fn;
54 elevator_add_req_fn *elevator_add_req_fn;
55 elevator_activate_req_fn *elevator_activate_req_fn;
56 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
57
58 elevator_completed_req_fn *elevator_completed_req_fn;
59
60 elevator_request_list_fn *elevator_former_req_fn;
61 elevator_request_list_fn *elevator_latter_req_fn;
62
63 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
64 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
65
66 elevator_set_req_fn *elevator_set_req_fn;
67 elevator_put_req_fn *elevator_put_req_fn;
68
69 elevator_may_queue_fn *elevator_may_queue_fn;
70
71 elevator_init_fn *elevator_init_fn;
72 elevator_exit_fn *elevator_exit_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/*
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 struct hlist_head *hash;
114 unsigned int registered:1;
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 int elv_try_merge(struct request *, struct bio *);
126extern void elv_merge_requests(struct request_queue *, struct request *,
127 struct request *);
128extern void elv_merged_request(struct request_queue *, struct request *, int);
129extern void elv_bio_merged(struct request_queue *q, struct request *,
130 struct bio *);
131extern void elv_requeue_request(struct request_queue *, struct request *);
132extern struct request *elv_former_request(struct request_queue *, struct request *);
133extern struct request *elv_latter_request(struct request_queue *, struct request *);
134extern int elv_register_queue(struct request_queue *q);
135extern void elv_unregister_queue(struct request_queue *q);
136extern int elv_may_queue(struct request_queue *, int);
137extern void elv_abort_queue(struct request_queue *);
138extern void elv_completed_request(struct request_queue *, struct request *);
139extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
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 int elv_register(struct elevator_type *);
147extern void elv_unregister(struct elevator_type *);
148
149/*
150 * io scheduler sysfs switching
151 */
152extern ssize_t elv_iosched_show(struct request_queue *, char *);
153extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
154
155extern int elevator_init(struct request_queue *, char *);
156extern void elevator_exit(struct elevator_queue *);
157extern int elevator_change(struct request_queue *, const char *);
158extern int elv_rq_merge_ok(struct request *, struct bio *);
159
160/*
161 * Helper functions.
162 */
163extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
164extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
165
166/*
167 * rb support functions.
168 */
169extern void elv_rb_add(struct rb_root *, struct request *);
170extern void elv_rb_del(struct rb_root *, struct request *);
171extern struct request *elv_rb_find(struct rb_root *, sector_t);
172
173/*
174 * Return values from elevator merger
175 */
176#define ELEVATOR_NO_MERGE 0
177#define ELEVATOR_FRONT_MERGE 1
178#define ELEVATOR_BACK_MERGE 2
179
180/*
181 * Insertion selection
182 */
183#define ELEVATOR_INSERT_FRONT 1
184#define ELEVATOR_INSERT_BACK 2
185#define ELEVATOR_INSERT_SORT 3
186#define ELEVATOR_INSERT_REQUEUE 4
187#define ELEVATOR_INSERT_FLUSH 5
188#define ELEVATOR_INSERT_SORT_MERGE 6
189
190/*
191 * return values from elevator_may_queue_fn
192 */
193enum {
194 ELV_MQUEUE_MAY,
195 ELV_MQUEUE_NO,
196 ELV_MQUEUE_MUST,
197};
198
199#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
200#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
201
202/*
203 * Hack to reuse the csd.list list_head as the fifo time holder while
204 * the request is in the io scheduler. Saves an unsigned long in rq.
205 */
206#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
207#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
208#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
209#define rq_fifo_clear(rq) do { \
210 list_del_init(&(rq)->queuelist); \
211 INIT_LIST_HEAD(&(rq)->csd.list); \
212 } while (0)
213
214#endif /* CONFIG_BLOCK */
215#endif