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