1#ifndef _LINUX_ELEVATOR_H
2#define _LINUX_ELEVATOR_H
3
4#include <linux/percpu.h>
5#include <linux/hashtable.h>
6
7#ifdef CONFIG_BLOCK
8
9struct io_cq;
10struct elevator_type;
11
12typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
13				 struct bio *);
14
15typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
16
17typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
18
19typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
20
21typedef void (elevator_bio_merged_fn) (struct request_queue *,
22						struct request *, struct bio *);
23
24typedef int (elevator_dispatch_fn) (struct request_queue *, int);
25
26typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
27typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
28typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
29typedef int (elevator_may_queue_fn) (struct request_queue *, int);
30
31typedef void (elevator_init_icq_fn) (struct io_cq *);
32typedef void (elevator_exit_icq_fn) (struct io_cq *);
33typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
34				   struct bio *, gfp_t);
35typedef void (elevator_put_req_fn) (struct request *);
36typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
37typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
38
39typedef int (elevator_init_fn) (struct request_queue *,
40				struct elevator_type *e);
41typedef void (elevator_exit_fn) (struct elevator_queue *);
42
43struct elevator_ops
44{
45	elevator_merge_fn *elevator_merge_fn;
46	elevator_merged_fn *elevator_merged_fn;
47	elevator_merge_req_fn *elevator_merge_req_fn;
48	elevator_allow_merge_fn *elevator_allow_merge_fn;
49	elevator_bio_merged_fn *elevator_bio_merged_fn;
50
51	elevator_dispatch_fn *elevator_dispatch_fn;
52	elevator_add_req_fn *elevator_add_req_fn;
53	elevator_activate_req_fn *elevator_activate_req_fn;
54	elevator_deactivate_req_fn *elevator_deactivate_req_fn;
55
56	elevator_completed_req_fn *elevator_completed_req_fn;
57
58	elevator_request_list_fn *elevator_former_req_fn;
59	elevator_request_list_fn *elevator_latter_req_fn;
60
61	elevator_init_icq_fn *elevator_init_icq_fn;	/* see iocontext.h */
62	elevator_exit_icq_fn *elevator_exit_icq_fn;	/* ditto */
63
64	elevator_set_req_fn *elevator_set_req_fn;
65	elevator_put_req_fn *elevator_put_req_fn;
66
67	elevator_may_queue_fn *elevator_may_queue_fn;
68
69	elevator_init_fn *elevator_init_fn;
70	elevator_exit_fn *elevator_exit_fn;
71};
72
73#define ELV_NAME_MAX	(16)
74
75struct elv_fs_entry {
76	struct attribute attr;
77	ssize_t (*show)(struct elevator_queue *, char *);
78	ssize_t (*store)(struct elevator_queue *, const char *, size_t);
79};
80
81/*
82 * identifies an elevator type, such as AS or deadline
83 */
84struct elevator_type
85{
86	/* managed by elevator core */
87	struct kmem_cache *icq_cache;
88
89	/* fields provided by elevator implementation */
90	struct elevator_ops ops;
91	size_t icq_size;	/* see iocontext.h */
92	size_t icq_align;	/* ditto */
93	struct elv_fs_entry *elevator_attrs;
94	char elevator_name[ELV_NAME_MAX];
95	struct module *elevator_owner;
96
97	/* managed by elevator core */
98	char icq_cache_name[ELV_NAME_MAX + 5];	/* elvname + "_io_cq" */
99	struct list_head list;
100};
101
102#define ELV_HASH_BITS 6
103
104/*
105 * each queue has an elevator_queue associated with it
106 */
107struct elevator_queue
108{
109	struct elevator_type *type;
110	void *elevator_data;
111	struct kobject kobj;
112	struct mutex sysfs_lock;
113	unsigned int registered:1;
114	DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
115};
116
117/*
118 * block elevator interface
119 */
120extern void elv_dispatch_sort(struct request_queue *, struct request *);
121extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
122extern void elv_add_request(struct request_queue *, struct request *, int);
123extern void __elv_add_request(struct request_queue *, struct request *, int);
124extern int elv_merge(struct request_queue *, struct request **, struct bio *);
125extern void elv_merge_requests(struct request_queue *, struct request *,
126			       struct request *);
127extern void elv_merged_request(struct request_queue *, struct request *, int);
128extern void elv_bio_merged(struct request_queue *q, struct request *,
129				struct bio *);
130extern void elv_requeue_request(struct request_queue *, struct request *);
131extern struct request *elv_former_request(struct request_queue *, struct request *);
132extern struct request *elv_latter_request(struct request_queue *, struct request *);
133extern int elv_register_queue(struct request_queue *q);
134extern void elv_unregister_queue(struct request_queue *q);
135extern int elv_may_queue(struct request_queue *, int);
136extern void elv_completed_request(struct request_queue *, struct request *);
137extern int elv_set_request(struct request_queue *q, struct request *rq,
138			   struct bio *bio, gfp_t gfp_mask);
139extern void elv_put_request(struct request_queue *, struct request *);
140extern void elv_drain_elevator(struct request_queue *);
141
142/*
143 * io scheduler registration
144 */
145extern void __init load_default_elevator_module(void);
146extern int elv_register(struct elevator_type *);
147extern void elv_unregister(struct elevator_type *);
148
149/*
150 * io scheduler sysfs switching
151 */
152extern ssize_t elv_iosched_show(struct request_queue *, char *);
153extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
154
155extern int elevator_init(struct request_queue *, char *);
156extern void elevator_exit(struct elevator_queue *);
157extern int elevator_change(struct request_queue *, const char *);
158extern bool elv_rq_merge_ok(struct request *, struct bio *);
159extern struct elevator_queue *elevator_alloc(struct request_queue *,
160					struct elevator_type *);
161
162/*
163 * Helper functions.
164 */
165extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
166extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
167
168/*
169 * rb support functions.
170 */
171extern void elv_rb_add(struct rb_root *, struct request *);
172extern void elv_rb_del(struct rb_root *, struct request *);
173extern struct request *elv_rb_find(struct rb_root *, sector_t);
174
175/*
176 * Return values from elevator merger
177 */
178#define ELEVATOR_NO_MERGE	0
179#define ELEVATOR_FRONT_MERGE	1
180#define ELEVATOR_BACK_MERGE	2
181
182/*
183 * Insertion selection
184 */
185#define ELEVATOR_INSERT_FRONT	1
186#define ELEVATOR_INSERT_BACK	2
187#define ELEVATOR_INSERT_SORT	3
188#define ELEVATOR_INSERT_REQUEUE	4
189#define ELEVATOR_INSERT_FLUSH	5
190#define ELEVATOR_INSERT_SORT_MERGE	6
191
192/*
193 * return values from elevator_may_queue_fn
194 */
195enum {
196	ELV_MQUEUE_MAY,
197	ELV_MQUEUE_NO,
198	ELV_MQUEUE_MUST,
199};
200
201#define rq_end_sector(rq)	(blk_rq_pos(rq) + blk_rq_sectors(rq))
202#define rb_entry_rq(node)	rb_entry((node), struct request, rb_node)
203
204#define rq_entry_fifo(ptr)	list_entry((ptr), struct request, queuelist)
205#define rq_fifo_clear(rq)	list_del_init(&(rq)->queuelist)
206
207#else /* CONFIG_BLOCK */
208
209static inline void load_default_elevator_module(void) { }
210
211#endif /* CONFIG_BLOCK */
212#endif
213