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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_resources {
36 /* holds elevator data */
37 void *data;
38 /* holds elevator tags */
39 struct elevator_tags *et;
40};
41
42/* Holding context data for changing elevator */
43struct elv_change_ctx {
44 const char *name;
45 bool no_uevent;
46
47 /* for unregistering old elevator */
48 struct elevator_queue *old;
49 /* for registering new elevator */
50 struct elevator_queue *new;
51 /* store elevator type */
52 struct elevator_type *type;
53 /* store elevator resources */
54 struct elevator_resources res;
55};
56
57struct elevator_mq_ops {
58 int (*init_sched)(struct request_queue *, struct elevator_queue *);
59 void (*exit_sched)(struct elevator_queue *);
60 int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
61 void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
62 void (*depth_updated)(struct request_queue *);
63 void *(*alloc_sched_data)(struct request_queue *);
64 void (*free_sched_data)(void *);
65
66 bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
67 bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
68 int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
69 void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
70 void (*requests_merged)(struct request_queue *, struct request *, struct request *);
71 void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
72 void (*prepare_request)(struct request *);
73 void (*finish_request)(struct request *);
74 void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
75 blk_insert_t flags);
76 struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
77 bool (*has_work)(struct blk_mq_hw_ctx *);
78 void (*completed_request)(struct request *, u64);
79 void (*requeue_request)(struct request *);
80 struct request *(*former_request)(struct request_queue *, struct request *);
81 struct request *(*next_request)(struct request_queue *, struct request *);
82 void (*init_icq)(struct io_cq *);
83 void (*exit_icq)(struct io_cq *);
84};
85
86#define ELV_NAME_MAX (16)
87
88struct elv_fs_entry {
89 struct attribute attr;
90 ssize_t (*show)(struct elevator_queue *, char *);
91 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
92};
93
94/*
95 * identifies an elevator type, such as AS or deadline
96 */
97struct elevator_type
98{
99 /* managed by elevator core */
100 struct kmem_cache *icq_cache;
101
102 /* fields provided by elevator implementation */
103 struct elevator_mq_ops ops;
104
105 size_t icq_size; /* see iocontext.h */
106 size_t icq_align; /* ditto */
107 const struct elv_fs_entry *elevator_attrs;
108 const char *elevator_name;
109 const char *elevator_alias;
110 struct module *elevator_owner;
111#ifdef CONFIG_BLK_DEBUG_FS
112 const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
113 const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
114#endif
115
116 /* managed by elevator core */
117 char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
118 struct list_head list;
119};
120
121static inline bool elevator_tryget(struct elevator_type *e)
122{
123 return try_module_get(e->elevator_owner);
124}
125
126static inline void __elevator_get(struct elevator_type *e)
127{
128 __module_get(e->elevator_owner);
129}
130
131static inline void elevator_put(struct elevator_type *e)
132{
133 module_put(e->elevator_owner);
134}
135
136#define ELV_HASH_BITS 6
137
138void elv_rqhash_del(struct request_queue *q, struct request *rq);
139void elv_rqhash_add(struct request_queue *q, struct request *rq);
140void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
141struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
142
143/*
144 * each queue has an elevator_queue associated with it
145 */
146struct elevator_queue
147{
148 struct elevator_type *type;
149 struct elevator_tags *et;
150 void *elevator_data;
151 struct kobject kobj;
152 struct mutex sysfs_lock;
153 unsigned long flags;
154 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
155};
156
157#define ELEVATOR_FLAG_REGISTERED 0
158#define ELEVATOR_FLAG_DYING 1
159
160/*
161 * block elevator interface
162 */
163extern enum elv_merge elv_merge(struct request_queue *, struct request **,
164 struct bio *);
165extern void elv_merge_requests(struct request_queue *, struct request *,
166 struct request *);
167extern void elv_merged_request(struct request_queue *, struct request *,
168 enum elv_merge);
169extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
170 struct list_head *);
171extern struct request *elv_former_request(struct request_queue *, struct request *);
172extern struct request *elv_latter_request(struct request_queue *, struct request *);
173
174/*
175 * io scheduler registration
176 */
177extern int elv_register(struct elevator_type *);
178extern void elv_unregister(struct elevator_type *);
179
180/*
181 * io scheduler sysfs switching
182 */
183ssize_t elv_iosched_show(struct gendisk *disk, char *page);
184ssize_t elv_iosched_store(struct gendisk *disk, const char *page, size_t count);
185
186extern bool elv_bio_merge_ok(struct request *, struct bio *);
187struct elevator_queue *elevator_alloc(struct request_queue *,
188 struct elevator_type *, struct elevator_resources *);
189
190/*
191 * Helper functions.
192 */
193extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
194extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
195
196/*
197 * rb support functions.
198 */
199extern void elv_rb_add(struct rb_root *, struct request *);
200extern void elv_rb_del(struct rb_root *, struct request *);
201extern struct request *elv_rb_find(struct rb_root *, sector_t);
202
203/*
204 * Insertion selection
205 */
206#define ELEVATOR_INSERT_FRONT 1
207#define ELEVATOR_INSERT_BACK 2
208#define ELEVATOR_INSERT_SORT 3
209#define ELEVATOR_INSERT_REQUEUE 4
210#define ELEVATOR_INSERT_FLUSH 5
211#define ELEVATOR_INSERT_SORT_MERGE 6
212
213#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
214
215#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
216#define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
217
218void blk_mq_sched_reg_debugfs(struct request_queue *q);
219void blk_mq_sched_unreg_debugfs(struct request_queue *q);
220
221#endif /* _ELEVATOR_H */