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
12/*
13 * Return values from elevator merger
14 */
15enum elv_merge {
16 ELEVATOR_NO_MERGE = 0,
17 ELEVATOR_FRONT_MERGE = 1,
18 ELEVATOR_BACK_MERGE = 2,
19 ELEVATOR_DISCARD_MERGE = 3,
20};
21
22typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
23 struct bio *);
24
25typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
26
27typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
28
29typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
30 struct request *, struct bio *);
31
32typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
33 struct request *, struct request *);
34
35typedef void (elevator_bio_merged_fn) (struct request_queue *,
36 struct request *, struct bio *);
37
38typedef int (elevator_dispatch_fn) (struct request_queue *, int);
39
40typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
41typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
42typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
43typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
44
45typedef void (elevator_init_icq_fn) (struct io_cq *);
46typedef void (elevator_exit_icq_fn) (struct io_cq *);
47typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
48 struct bio *, gfp_t);
49typedef void (elevator_put_req_fn) (struct request *);
50typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
51typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
52
53typedef int (elevator_init_fn) (struct request_queue *,
54 struct elevator_type *e);
55typedef void (elevator_exit_fn) (struct elevator_queue *);
56typedef void (elevator_registered_fn) (struct request_queue *);
57
58struct elevator_ops
59{
60 elevator_merge_fn *elevator_merge_fn;
61 elevator_merged_fn *elevator_merged_fn;
62 elevator_merge_req_fn *elevator_merge_req_fn;
63 elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
64 elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
65 elevator_bio_merged_fn *elevator_bio_merged_fn;
66
67 elevator_dispatch_fn *elevator_dispatch_fn;
68 elevator_add_req_fn *elevator_add_req_fn;
69 elevator_activate_req_fn *elevator_activate_req_fn;
70 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
71
72 elevator_completed_req_fn *elevator_completed_req_fn;
73
74 elevator_request_list_fn *elevator_former_req_fn;
75 elevator_request_list_fn *elevator_latter_req_fn;
76
77 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
78 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
79
80 elevator_set_req_fn *elevator_set_req_fn;
81 elevator_put_req_fn *elevator_put_req_fn;
82
83 elevator_may_queue_fn *elevator_may_queue_fn;
84
85 elevator_init_fn *elevator_init_fn;
86 elevator_exit_fn *elevator_exit_fn;
87 elevator_registered_fn *elevator_registered_fn;
88};
89
90struct blk_mq_alloc_data;
91struct blk_mq_hw_ctx;
92
93struct elevator_mq_ops {
94 int (*init_sched)(struct request_queue *, struct elevator_type *);
95 void (*exit_sched)(struct elevator_queue *);
96
97 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
98 bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
99 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
100 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
101 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
102 struct request *(*get_request)(struct request_queue *, unsigned int, struct blk_mq_alloc_data *);
103 void (*put_request)(struct request *);
104 void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
105 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
106 bool (*has_work)(struct blk_mq_hw_ctx *);
107 void (*completed_request)(struct blk_mq_hw_ctx *, struct request *);
108 void (*started_request)(struct request *);
109 void (*requeue_request)(struct request *);
110 struct request *(*former_request)(struct request_queue *, struct request *);
111 struct request *(*next_request)(struct request_queue *, struct request *);
112 int (*get_rq_priv)(struct request_queue *, struct request *, struct bio *);
113 void (*put_rq_priv)(struct request_queue *, struct request *);
114 void (*init_icq)(struct io_cq *);
115 void (*exit_icq)(struct io_cq *);
116};
117
118#define ELV_NAME_MAX (16)
119
120struct elv_fs_entry {
121 struct attribute attr;
122 ssize_t (*show)(struct elevator_queue *, char *);
123 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
124};
125
126/*
127 * identifies an elevator type, such as AS or deadline
128 */
129struct elevator_type
130{
131 /* managed by elevator core */
132 struct kmem_cache *icq_cache;
133
134 /* fields provided by elevator implementation */
135 union {
136 struct elevator_ops sq;
137 struct elevator_mq_ops mq;
138 } ops;
139 size_t icq_size; /* see iocontext.h */
140 size_t icq_align; /* ditto */
141 struct elv_fs_entry *elevator_attrs;
142 char elevator_name[ELV_NAME_MAX];
143 struct module *elevator_owner;
144 bool uses_mq;
145
146 /* managed by elevator core */
147 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
148 struct list_head list;
149};
150
151#define ELV_HASH_BITS 6
152
153void elv_rqhash_del(struct request_queue *q, struct request *rq);
154void elv_rqhash_add(struct request_queue *q, struct request *rq);
155void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
156struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
157
158/*
159 * each queue has an elevator_queue associated with it
160 */
161struct elevator_queue
162{
163 struct elevator_type *type;
164 void *elevator_data;
165 struct kobject kobj;
166 struct mutex sysfs_lock;
167 unsigned int registered:1;
168 unsigned int uses_mq:1;
169 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
170};
171
172/*
173 * block elevator interface
174 */
175extern void elv_dispatch_sort(struct request_queue *, struct request *);
176extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
177extern void elv_add_request(struct request_queue *, struct request *, int);
178extern void __elv_add_request(struct request_queue *, struct request *, int);
179extern enum elv_merge elv_merge(struct request_queue *, struct request **,
180 struct bio *);
181extern void elv_merge_requests(struct request_queue *, struct request *,
182 struct request *);
183extern void elv_merged_request(struct request_queue *, struct request *,
184 enum elv_merge);
185extern void elv_bio_merged(struct request_queue *q, struct request *,
186 struct bio *);
187extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
188extern void elv_requeue_request(struct request_queue *, struct request *);
189extern struct request *elv_former_request(struct request_queue *, struct request *);
190extern struct request *elv_latter_request(struct request_queue *, struct request *);
191extern int elv_register_queue(struct request_queue *q);
192extern void elv_unregister_queue(struct request_queue *q);
193extern int elv_may_queue(struct request_queue *, unsigned int);
194extern void elv_completed_request(struct request_queue *, struct request *);
195extern int elv_set_request(struct request_queue *q, struct request *rq,
196 struct bio *bio, gfp_t gfp_mask);
197extern void elv_put_request(struct request_queue *, struct request *);
198extern void elv_drain_elevator(struct request_queue *);
199
200/*
201 * io scheduler registration
202 */
203extern void __init load_default_elevator_module(void);
204extern int elv_register(struct elevator_type *);
205extern void elv_unregister(struct elevator_type *);
206
207/*
208 * io scheduler sysfs switching
209 */
210extern ssize_t elv_iosched_show(struct request_queue *, char *);
211extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
212
213extern int elevator_init(struct request_queue *, char *);
214extern void elevator_exit(struct request_queue *, struct elevator_queue *);
215extern int elevator_change(struct request_queue *, const char *);
216extern bool elv_bio_merge_ok(struct request *, struct bio *);
217extern struct elevator_queue *elevator_alloc(struct request_queue *,
218 struct elevator_type *);
219
220/*
221 * Helper functions.
222 */
223extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
224extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
225
226/*
227 * rb support functions.
228 */
229extern void elv_rb_add(struct rb_root *, struct request *);
230extern void elv_rb_del(struct rb_root *, struct request *);
231extern struct request *elv_rb_find(struct rb_root *, sector_t);
232
233/*
234 * Insertion selection
235 */
236#define ELEVATOR_INSERT_FRONT 1
237#define ELEVATOR_INSERT_BACK 2
238#define ELEVATOR_INSERT_SORT 3
239#define ELEVATOR_INSERT_REQUEUE 4
240#define ELEVATOR_INSERT_FLUSH 5
241#define ELEVATOR_INSERT_SORT_MERGE 6
242
243/*
244 * return values from elevator_may_queue_fn
245 */
246enum {
247 ELV_MQUEUE_MAY,
248 ELV_MQUEUE_NO,
249 ELV_MQUEUE_MUST,
250};
251
252#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
253#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
254
255#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
256#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
257
258#else /* CONFIG_BLOCK */
259
260static inline void load_default_elevator_module(void) { }
261
262#endif /* CONFIG_BLOCK */
263#endif