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_tags {
27 /* num. of hardware queues for which tags are allocated */
28 unsigned int nr_hw_queues;
29 /* depth used while allocating tags */
30 unsigned int nr_requests;
31 /* shared tag is stored at index 0 */
32 struct blk_mq_tags *tags[];
33};
34
35struct elevator_mq_ops {
36 int (*init_sched)(struct request_queue *, struct elevator_queue *);
37 void (*exit_sched)(struct elevator_queue *);
38 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
39 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
40 void (*depth_updated)(struct request_queue *);
41
42 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
43 bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
44 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
45 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
46 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
47 void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
48 void (*prepare_request)(struct request *);
49 void (*finish_request)(struct request *);
50 void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
51 blk_insert_t flags);
52 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
53 bool (*has_work)(struct blk_mq_hw_ctx *);
54 void (*completed_request)(struct request *, u64);
55 void (*requeue_request)(struct request *);
56 struct request *(*former_request)(struct request_queue *, struct request *);
57 struct request *(*next_request)(struct request_queue *, struct request *);
58 void (*init_icq)(struct io_cq *);
59 void (*exit_icq)(struct io_cq *);
60};
61
62#define ELV_NAME_MAX (16)
63
64struct elv_fs_entry {
65 struct attribute attr;
66 ssize_t (*show)(struct elevator_queue *, char *);
67 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
68};
69
70/*
71 * identifies an elevator type, such as AS or deadline
72 */
73struct elevator_type
74{
75 /* managed by elevator core */
76 struct kmem_cache *icq_cache;
77
78 /* fields provided by elevator implementation */
79 struct elevator_mq_ops ops;
80
81 size_t icq_size; /* see iocontext.h */
82 size_t icq_align; /* ditto */
83 const struct elv_fs_entry *elevator_attrs;
84 const char *elevator_name;
85 const char *elevator_alias;
86 struct module *elevator_owner;
87#ifdef CONFIG_BLK_DEBUG_FS
88 const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
89 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
90#endif
91
92 /* managed by elevator core */
93 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
94 struct list_head list;
95};
96
97static inline bool elevator_tryget(struct elevator_type *e)
98{
99 return try_module_get(module: e->elevator_owner);
100}
101
102static inline void __elevator_get(struct elevator_type *e)
103{
104 __module_get(module: e->elevator_owner);
105}
106
107static inline void elevator_put(struct elevator_type *e)
108{
109 module_put(module: e->elevator_owner);
110}
111
112#define ELV_HASH_BITS 6
113
114void elv_rqhash_del(struct request_queue *q, struct request *rq);
115void elv_rqhash_add(struct request_queue *q, struct request *rq);
116void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
117struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
118
119/*
120 * each queue has an elevator_queue associated with it
121 */
122struct elevator_queue
123{
124 struct elevator_type *type;
125 struct elevator_tags *et;
126 void *elevator_data;
127 struct kobject kobj;
128 struct mutex sysfs_lock;
129 unsigned long flags;
130 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
131};
132
133#define ELEVATOR_FLAG_REGISTERED 0
134#define ELEVATOR_FLAG_DYING 1
135#define ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT 2
136
137/*
138 * block elevator interface
139 */
140extern enum elv_merge elv_merge(struct request_queue *, struct request **,
141 struct bio *);
142extern void elv_merge_requests(struct request_queue *, struct request *,
143 struct request *);
144extern void elv_merged_request(struct request_queue *, struct request *,
145 enum elv_merge);
146extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
147 struct list_head *);
148extern struct request *elv_former_request(struct request_queue *, struct request *);
149extern struct request *elv_latter_request(struct request_queue *, struct request *);
150void elevator_init_mq(struct request_queue *q);
151
152/*
153 * io scheduler registration
154 */
155extern int elv_register(struct elevator_type *);
156extern void elv_unregister(struct elevator_type *);
157
158/*
159 * io scheduler sysfs switching
160 */
161ssize_t elv_iosched_show(struct gendisk *disk, char *page);
162ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count);
163
164extern bool elv_bio_merge_ok(struct request *, struct bio *);
165struct elevator_queue *elevator_alloc(struct request_queue *,
166 struct elevator_type *, struct elevator_tags *);
167
168/*
169 * Helper functions.
170 */
171extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
172extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
173
174/*
175 * rb support functions.
176 */
177extern void elv_rb_add(struct rb_root *, struct request *);
178extern void elv_rb_del(struct rb_root *, struct request *);
179extern struct request *elv_rb_find(struct rb_root *, sector_t);
180
181/*
182 * Insertion selection
183 */
184#define ELEVATOR_INSERT_FRONT 1
185#define ELEVATOR_INSERT_BACK 2
186#define ELEVATOR_INSERT_SORT 3
187#define ELEVATOR_INSERT_REQUEUE 4
188#define ELEVATOR_INSERT_FLUSH 5
189#define ELEVATOR_INSERT_SORT_MERGE 6
190
191#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
192
193#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
194#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
195
196void blk_mq_sched_reg_debugfs(struct request_queue *q);
197void blk_mq_sched_unreg_debugfs(struct request_queue *q);
198
199#endif /* _ELEVATOR_H */
200