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#ifdef CONFIG_BLK_DEBUG_FS
12struct blk_mq_debugfs_attr;
13#endif
14
15/*
16 * Return values from elevator merger
17 */
18enum elv_merge {
19 ELEVATOR_NO_MERGE = 0,
20 ELEVATOR_FRONT_MERGE = 1,
21 ELEVATOR_BACK_MERGE = 2,
22 ELEVATOR_DISCARD_MERGE = 3,
23};
24
25typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
26 struct bio *);
27
28typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
29
30typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
31
32typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
33 struct request *, struct bio *);
34
35typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
36 struct request *, struct request *);
37
38typedef void (elevator_bio_merged_fn) (struct request_queue *,
39 struct request *, struct bio *);
40
41typedef int (elevator_dispatch_fn) (struct request_queue *, int);
42
43typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
44typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
45typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
46typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
47
48typedef void (elevator_init_icq_fn) (struct io_cq *);
49typedef void (elevator_exit_icq_fn) (struct io_cq *);
50typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
51 struct bio *, gfp_t);
52typedef void (elevator_put_req_fn) (struct request *);
53typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
54typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
55
56typedef int (elevator_init_fn) (struct request_queue *,
57 struct elevator_type *e);
58typedef void (elevator_exit_fn) (struct elevator_queue *);
59typedef void (elevator_registered_fn) (struct request_queue *);
60
61struct elevator_ops
62{
63 elevator_merge_fn *elevator_merge_fn;
64 elevator_merged_fn *elevator_merged_fn;
65 elevator_merge_req_fn *elevator_merge_req_fn;
66 elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
67 elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
68 elevator_bio_merged_fn *elevator_bio_merged_fn;
69
70 elevator_dispatch_fn *elevator_dispatch_fn;
71 elevator_add_req_fn *elevator_add_req_fn;
72 elevator_activate_req_fn *elevator_activate_req_fn;
73 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
74
75 elevator_completed_req_fn *elevator_completed_req_fn;
76
77 elevator_request_list_fn *elevator_former_req_fn;
78 elevator_request_list_fn *elevator_latter_req_fn;
79
80 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
81 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
82
83 elevator_set_req_fn *elevator_set_req_fn;
84 elevator_put_req_fn *elevator_put_req_fn;
85
86 elevator_may_queue_fn *elevator_may_queue_fn;
87
88 elevator_init_fn *elevator_init_fn;
89 elevator_exit_fn *elevator_exit_fn;
90 elevator_registered_fn *elevator_registered_fn;
91};
92
93struct blk_mq_alloc_data;
94struct blk_mq_hw_ctx;
95
96struct elevator_mq_ops {
97 int (*init_sched)(struct request_queue *, struct elevator_type *);
98 void (*exit_sched)(struct elevator_queue *);
99 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
100 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
101
102 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
103 bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
104 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
105 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
106 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
107 void (*limit_depth)(unsigned int, struct blk_mq_alloc_data *);
108 void (*prepare_request)(struct request *, struct bio *bio);
109 void (*finish_request)(struct request *);
110 void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
111 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
112 bool (*has_work)(struct blk_mq_hw_ctx *);
113 void (*completed_request)(struct request *);
114 void (*started_request)(struct request *);
115 void (*requeue_request)(struct request *);
116 struct request *(*former_request)(struct request_queue *, struct request *);
117 struct request *(*next_request)(struct request_queue *, struct request *);
118 void (*init_icq)(struct io_cq *);
119 void (*exit_icq)(struct io_cq *);
120};
121
122#define ELV_NAME_MAX (16)
123
124struct elv_fs_entry {
125 struct attribute attr;
126 ssize_t (*show)(struct elevator_queue *, char *);
127 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
128};
129
130/*
131 * identifies an elevator type, such as AS or deadline
132 */
133struct elevator_type
134{
135 /* managed by elevator core */
136 struct kmem_cache *icq_cache;
137
138 /* fields provided by elevator implementation */
139 union {
140 struct elevator_ops sq;
141 struct elevator_mq_ops mq;
142 } ops;
143 size_t icq_size; /* see iocontext.h */
144 size_t icq_align; /* ditto */
145 struct elv_fs_entry *elevator_attrs;
146 char elevator_name[ELV_NAME_MAX];
147 struct module *elevator_owner;
148 bool uses_mq;
149#ifdef CONFIG_BLK_DEBUG_FS
150 const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
151 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
152#endif
153
154 /* managed by elevator core */
155 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
156 struct list_head list;
157};
158
159#define ELV_HASH_BITS 6
160
161void elv_rqhash_del(struct request_queue *q, struct request *rq);
162void elv_rqhash_add(struct request_queue *q, struct request *rq);
163void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
164struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
165
166/*
167 * each queue has an elevator_queue associated with it
168 */
169struct elevator_queue
170{
171 struct elevator_type *type;
172 void *elevator_data;
173 struct kobject kobj;
174 struct mutex sysfs_lock;
175 unsigned int registered:1;
176 unsigned int uses_mq:1;
177 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
178};
179
180/*
181 * block elevator interface
182 */
183extern void elv_dispatch_sort(struct request_queue *, struct request *);
184extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
185extern void elv_add_request(struct request_queue *, struct request *, int);
186extern void __elv_add_request(struct request_queue *, struct request *, int);
187extern enum elv_merge elv_merge(struct request_queue *, struct request **,
188 struct bio *);
189extern void elv_merge_requests(struct request_queue *, struct request *,
190 struct request *);
191extern void elv_merged_request(struct request_queue *, struct request *,
192 enum elv_merge);
193extern void elv_bio_merged(struct request_queue *q, struct request *,
194 struct bio *);
195extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
196extern void elv_requeue_request(struct request_queue *, struct request *);
197extern struct request *elv_former_request(struct request_queue *, struct request *);
198extern struct request *elv_latter_request(struct request_queue *, struct request *);
199extern int elv_register_queue(struct request_queue *q);
200extern void elv_unregister_queue(struct request_queue *q);
201extern int elv_may_queue(struct request_queue *, unsigned int);
202extern void elv_completed_request(struct request_queue *, struct request *);
203extern int elv_set_request(struct request_queue *q, struct request *rq,
204 struct bio *bio, gfp_t gfp_mask);
205extern void elv_put_request(struct request_queue *, struct request *);
206extern void elv_drain_elevator(struct request_queue *);
207
208/*
209 * io scheduler registration
210 */
211extern void __init load_default_elevator_module(void);
212extern int elv_register(struct elevator_type *);
213extern void elv_unregister(struct elevator_type *);
214
215/*
216 * io scheduler sysfs switching
217 */
218extern ssize_t elv_iosched_show(struct request_queue *, char *);
219extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
220
221extern int elevator_init(struct request_queue *, char *);
222extern void elevator_exit(struct request_queue *, struct elevator_queue *);
223extern bool elv_bio_merge_ok(struct request *, struct bio *);
224extern struct elevator_queue *elevator_alloc(struct request_queue *,
225 struct elevator_type *);
226
227/*
228 * Helper functions.
229 */
230extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
231extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
232
233/*
234 * rb support functions.
235 */
236extern void elv_rb_add(struct rb_root *, struct request *);
237extern void elv_rb_del(struct rb_root *, struct request *);
238extern struct request *elv_rb_find(struct rb_root *, sector_t);
239
240/*
241 * Insertion selection
242 */
243#define ELEVATOR_INSERT_FRONT 1
244#define ELEVATOR_INSERT_BACK 2
245#define ELEVATOR_INSERT_SORT 3
246#define ELEVATOR_INSERT_REQUEUE 4
247#define ELEVATOR_INSERT_FLUSH 5
248#define ELEVATOR_INSERT_SORT_MERGE 6
249
250/*
251 * return values from elevator_may_queue_fn
252 */
253enum {
254 ELV_MQUEUE_MAY,
255 ELV_MQUEUE_NO,
256 ELV_MQUEUE_MUST,
257};
258
259#define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
260#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
261
262#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
263#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
264
265#else /* CONFIG_BLOCK */
266
267static inline void load_default_elevator_module(void) { }
268
269#endif /* CONFIG_BLOCK */
270#endif