1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_ELEVATOR_H
3 #define _LINUX_ELEVATOR_H
4
5 #include <linux/percpu.h>
6 #include <linux/hashtable.h>
7
8 #ifdef CONFIG_BLOCK
9
10 struct io_cq;
11 struct elevator_type;
12 #ifdef CONFIG_BLK_DEBUG_FS
13 struct blk_mq_debugfs_attr;
14 #endif
15
16 /*
17 * Return values from elevator merger
18 */
19 enum elv_merge {
20 ELEVATOR_NO_MERGE = 0,
21 ELEVATOR_FRONT_MERGE = 1,
22 ELEVATOR_BACK_MERGE = 2,
23 ELEVATOR_DISCARD_MERGE = 3,
24 };
25
26 typedef enum elv_merge (elevator_merge_fn) (struct request_queue *, struct request **,
27 struct bio *);
28
29 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
30
31 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, enum elv_merge);
32
33 typedef int (elevator_allow_bio_merge_fn) (struct request_queue *,
34 struct request *, struct bio *);
35
36 typedef int (elevator_allow_rq_merge_fn) (struct request_queue *,
37 struct request *, struct request *);
38
39 typedef void (elevator_bio_merged_fn) (struct request_queue *,
40 struct request *, struct bio *);
41
42 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
43
44 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
45 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
46 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
47 typedef int (elevator_may_queue_fn) (struct request_queue *, unsigned int);
48
49 typedef void (elevator_init_icq_fn) (struct io_cq *);
50 typedef void (elevator_exit_icq_fn) (struct io_cq *);
51 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
52 struct bio *, gfp_t);
53 typedef void (elevator_put_req_fn) (struct request *);
54 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
55 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
56
57 typedef int (elevator_init_fn) (struct request_queue *,
58 struct elevator_type *e);
59 typedef void (elevator_exit_fn) (struct elevator_queue *);
60 typedef void (elevator_registered_fn) (struct request_queue *);
61
62 struct elevator_ops
63 {
64 elevator_merge_fn *elevator_merge_fn;
65 elevator_merged_fn *elevator_merged_fn;
66 elevator_merge_req_fn *elevator_merge_req_fn;
67 elevator_allow_bio_merge_fn *elevator_allow_bio_merge_fn;
68 elevator_allow_rq_merge_fn *elevator_allow_rq_merge_fn;
69 elevator_bio_merged_fn *elevator_bio_merged_fn;
70
71 elevator_dispatch_fn *elevator_dispatch_fn;
72 elevator_add_req_fn *elevator_add_req_fn;
73 elevator_activate_req_fn *elevator_activate_req_fn;
74 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
75
76 elevator_completed_req_fn *elevator_completed_req_fn;
77
78 elevator_request_list_fn *elevator_former_req_fn;
79 elevator_request_list_fn *elevator_latter_req_fn;
80
81 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
82 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
83
84 elevator_set_req_fn *elevator_set_req_fn;
85 elevator_put_req_fn *elevator_put_req_fn;
86
87 elevator_may_queue_fn *elevator_may_queue_fn;
88
89 elevator_init_fn *elevator_init_fn;
90 elevator_exit_fn *elevator_exit_fn;
91 elevator_registered_fn *elevator_registered_fn;
92 };
93
94 struct blk_mq_alloc_data;
95 struct blk_mq_hw_ctx;
96
97 struct elevator_mq_ops {
98 int (*init_sched)(struct request_queue *, struct elevator_type *);
99 void (*exit_sched)(struct elevator_queue *);
100 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
101 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
102
103 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
104 bool (*bio_merge)(struct blk_mq_hw_ctx *, struct bio *);
105 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
106 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
107 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
108 void (*limit_depth)(unsigned int, struct blk_mq_alloc_data *);
109 void (*prepare_request)(struct request *, struct bio *bio);
110 void (*finish_request)(struct request *);
111 void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
112 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
113 bool (*has_work)(struct blk_mq_hw_ctx *);
114 void (*completed_request)(struct request *);
115 void (*started_request)(struct request *);
116 void (*requeue_request)(struct request *);
117 struct request *(*former_request)(struct request_queue *, struct request *);
118 struct request *(*next_request)(struct request_queue *, struct request *);
119 void (*init_icq)(struct io_cq *);
120 void (*exit_icq)(struct io_cq *);
121 };
122
123 #define ELV_NAME_MAX (16)
124
125 struct elv_fs_entry {
126 struct attribute attr;
127 ssize_t (*show)(struct elevator_queue *, char *);
128 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
129 };
130
131 /*
132 * identifies an elevator type, such as AS or deadline
133 */
134 struct elevator_type
135 {
136 /* managed by elevator core */
137 struct kmem_cache *icq_cache;
138
139 /* fields provided by elevator implementation */
140 union {
141 struct elevator_ops sq;
142 struct elevator_mq_ops mq;
143 } ops;
144 size_t icq_size; /* see iocontext.h */
145 size_t icq_align; /* ditto */
146 struct elv_fs_entry *elevator_attrs;
147 char elevator_name[ELV_NAME_MAX];
148 const char *elevator_alias;
149 struct module *elevator_owner;
150 bool uses_mq;
151 #ifdef CONFIG_BLK_DEBUG_FS
152 const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
153 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
154 #endif
155
156 /* managed by elevator core */
157 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
158 struct list_head list;
159 };
160
161 #define ELV_HASH_BITS 6
162
163 void elv_rqhash_del(struct request_queue *q, struct request *rq);
164 void elv_rqhash_add(struct request_queue *q, struct request *rq);
165 void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
166 struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
167
168 /*
169 * each queue has an elevator_queue associated with it
170 */
171 struct elevator_queue
172 {
173 struct elevator_type *type;
174 void *elevator_data;
175 struct kobject kobj;
176 struct mutex sysfs_lock;
177 unsigned int registered:1;
178 unsigned int uses_mq:1;
179 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
180 };
181
182 /*
183 * block elevator interface
184 */
185 extern void elv_dispatch_sort(struct request_queue *, struct request *);
186 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
187 extern void elv_add_request(struct request_queue *, struct request *, int);
188 extern void __elv_add_request(struct request_queue *, struct request *, int);
189 extern enum elv_merge elv_merge(struct request_queue *, struct request **,
190 struct bio *);
191 extern void elv_merge_requests(struct request_queue *, struct request *,
192 struct request *);
193 extern void elv_merged_request(struct request_queue *, struct request *,
194 enum elv_merge);
195 extern void elv_bio_merged(struct request_queue *q, struct request *,
196 struct bio *);
197 extern bool elv_attempt_insert_merge(struct request_queue *, struct request *);
198 extern void elv_requeue_request(struct request_queue *, struct request *);
199 extern struct request *elv_former_request(struct request_queue *, struct request *);
200 extern struct request *elv_latter_request(struct request_queue *, struct request *);
201 extern int elv_may_queue(struct request_queue *, unsigned int);
202 extern void elv_completed_request(struct request_queue *, struct request *);
203 extern int elv_set_request(struct request_queue *q, struct request *rq,
204 struct bio *bio, gfp_t gfp_mask);
205 extern void elv_put_request(struct request_queue *, struct request *);
206 extern void elv_drain_elevator(struct request_queue *);
207
208 /*
209 * io scheduler registration
210 */
211 extern void __init load_default_elevator_module(void);
212 extern int elv_register(struct elevator_type *);
213 extern void elv_unregister(struct elevator_type *);
214
215 /*
216 * io scheduler sysfs switching
217 */
218 extern ssize_t elv_iosched_show(struct request_queue *, char *);
219 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
220
221 extern bool elv_bio_merge_ok(struct request *, struct bio *);
222 extern struct elevator_queue *elevator_alloc(struct request_queue *,
223 struct elevator_type *);
224
225 /*
226 * Helper functions.
227 */
228 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
229 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
230
231 /*
232 * rb support functions.
233 */
234 extern void elv_rb_add(struct rb_root *, struct request *);
235 extern void elv_rb_del(struct rb_root *, struct request *);
236 extern struct request *elv_rb_find(struct rb_root *, sector_t);
237
238 /*
239 * Insertion selection
240 */
241 #define ELEVATOR_INSERT_FRONT 1
242 #define ELEVATOR_INSERT_BACK 2
243 #define ELEVATOR_INSERT_SORT 3
244 #define ELEVATOR_INSERT_REQUEUE 4
245 #define ELEVATOR_INSERT_FLUSH 5
246 #define ELEVATOR_INSERT_SORT_MERGE 6
247
248 /*
249 * return values from elevator_may_queue_fn
250 */
251 enum {
252 ELV_MQUEUE_MAY,
253 ELV_MQUEUE_NO,
254 ELV_MQUEUE_MUST,
255 };
256
257 #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
258 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
259
260 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
261 #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
262
263 #else /* CONFIG_BLOCK */
264
load_default_elevator_module(void)265 static inline void load_default_elevator_module(void) { }
266
267 #endif /* CONFIG_BLOCK */
268 #endif
269
