1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ELEVATOR_H
3#define _ELEVATOR_H
4
5#include <linux/percpu.h>
6#include <linux/hashtable.h>
7#include "blk-mq.h"
8
9struct io_cq;
10struct elevator_type;
11struct blk_mq_debugfs_attr;
12
13/*
14 * Return values from elevator merger
15 */
16enum elv_merge {
17 ELEVATOR_NO_MERGE = 0,
18 ELEVATOR_FRONT_MERGE = 1,
19 ELEVATOR_BACK_MERGE = 2,
20 ELEVATOR_DISCARD_MERGE = 3,
21};
22
23struct blk_mq_alloc_data;
24struct blk_mq_hw_ctx;
25
26struct elevator_mq_ops {
27 int (*init_sched)(struct request_queue *, struct elevator_type *);
28 void (*exit_sched)(struct elevator_queue *);
29 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
30 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
31 void (*depth_updated)(struct blk_mq_hw_ctx *);
32
33 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
34 bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
35 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
36 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
37 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
38 void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
39 void (*prepare_request)(struct request *);
40 void (*finish_request)(struct request *);
41 void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
42 blk_insert_t flags);
43 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
44 bool (*has_work)(struct blk_mq_hw_ctx *);
45 void (*completed_request)(struct request *, u64);
46 void (*requeue_request)(struct request *);
47 struct request *(*former_request)(struct request_queue *, struct request *);
48 struct request *(*next_request)(struct request_queue *, struct request *);
49 void (*init_icq)(struct io_cq *);
50 void (*exit_icq)(struct io_cq *);
51};
52
53#define ELV_NAME_MAX (16)
54
55struct elv_fs_entry {
56 struct attribute attr;
57 ssize_t (*show)(struct elevator_queue *, char *);
58 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
59};
60
61/*
62 * identifies an elevator type, such as AS or deadline
63 */
64struct elevator_type
65{
66 /* managed by elevator core */
67 struct kmem_cache *icq_cache;
68
69 /* fields provided by elevator implementation */
70 struct elevator_mq_ops ops;
71
72 size_t icq_size; /* see iocontext.h */
73 size_t icq_align; /* ditto */
74 struct elv_fs_entry *elevator_attrs;
75 const char *elevator_name;
76 const char *elevator_alias;
77 const unsigned int elevator_features;
78 struct module *elevator_owner;
79#ifdef CONFIG_BLK_DEBUG_FS
80 const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
81 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
82#endif
83
84 /* managed by elevator core */
85 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
86 struct list_head list;
87};
88
89static inline bool elevator_tryget(struct elevator_type *e)
90{
91 return try_module_get(module: e->elevator_owner);
92}
93
94static inline void __elevator_get(struct elevator_type *e)
95{
96 __module_get(module: e->elevator_owner);
97}
98
99static inline void elevator_put(struct elevator_type *e)
100{
101 module_put(module: e->elevator_owner);
102}
103
104#define ELV_HASH_BITS 6
105
106void elv_rqhash_del(struct request_queue *q, struct request *rq);
107void elv_rqhash_add(struct request_queue *q, struct request *rq);
108void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
109struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
110
111/*
112 * each queue has an elevator_queue associated with it
113 */
114struct elevator_queue
115{
116 struct elevator_type *type;
117 void *elevator_data;
118 struct kobject kobj;
119 struct mutex sysfs_lock;
120 unsigned long flags;
121 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
122};
123
124#define ELEVATOR_FLAG_REGISTERED 0
125#define ELEVATOR_FLAG_DISABLE_WBT 1
126
127/*
128 * block elevator interface
129 */
130extern enum elv_merge elv_merge(struct request_queue *, struct request **,
131 struct bio *);
132extern void elv_merge_requests(struct request_queue *, struct request *,
133 struct request *);
134extern void elv_merged_request(struct request_queue *, struct request *,
135 enum elv_merge);
136extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
137 struct list_head *);
138extern struct request *elv_former_request(struct request_queue *, struct request *);
139extern struct request *elv_latter_request(struct request_queue *, struct request *);
140void elevator_init_mq(struct request_queue *q);
141
142/*
143 * io scheduler registration
144 */
145extern int elv_register(struct elevator_type *);
146extern void elv_unregister(struct elevator_type *);
147
148/*
149 * io scheduler sysfs switching
150 */
151extern ssize_t elv_iosched_show(struct request_queue *, char *);
152extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
153
154extern bool elv_bio_merge_ok(struct request *, struct bio *);
155extern struct elevator_queue *elevator_alloc(struct request_queue *,
156 struct elevator_type *);
157
158/*
159 * Helper functions.
160 */
161extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
162extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
163
164/*
165 * rb support functions.
166 */
167extern void elv_rb_add(struct rb_root *, struct request *);
168extern void elv_rb_del(struct rb_root *, struct request *);
169extern struct request *elv_rb_find(struct rb_root *, sector_t);
170
171/*
172 * Insertion selection
173 */
174#define ELEVATOR_INSERT_FRONT 1
175#define ELEVATOR_INSERT_BACK 2
176#define ELEVATOR_INSERT_SORT 3
177#define ELEVATOR_INSERT_REQUEUE 4
178#define ELEVATOR_INSERT_FLUSH 5
179#define ELEVATOR_INSERT_SORT_MERGE 6
180
181#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
182
183#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
184#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
185
186#endif /* _ELEVATOR_H */
187

source code of linux/block/elevator.h