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(e->elevator_owner);
 92}
 93
 94static inline void __elevator_get(struct elevator_type *e)
 95{
 96	__module_get(e->elevator_owner);
 97}
 98
 99static inline void elevator_put(struct elevator_type *e)
100{
101	module_put(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 */