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