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
9 struct io_cq;
10 struct elevator_type;
11
12 typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
13 struct bio *);
14
15 typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
16
17 typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
18
19 typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
20
21 typedef void (elevator_bio_merged_fn) (struct request_queue *,
22 struct request *, struct bio *);
23
24 typedef int (elevator_dispatch_fn) (struct request_queue *, int);
25
26 typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
27 typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
28 typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
29 typedef int (elevator_may_queue_fn) (struct request_queue *, int);
30
31 typedef void (elevator_init_icq_fn) (struct io_cq *);
32 typedef void (elevator_exit_icq_fn) (struct io_cq *);
33 typedef int (elevator_set_req_fn) (struct request_queue *, struct request *,
34 struct bio *, gfp_t);
35 typedef void (elevator_put_req_fn) (struct request *);
36 typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
37 typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
38
39 typedef int (elevator_init_fn) (struct request_queue *,
40 struct elevator_type *e);
41 typedef void (elevator_exit_fn) (struct elevator_queue *);
42 typedef void (elevator_registered_fn) (struct request_queue *);
43
44 struct elevator_ops
45 {
46 elevator_merge_fn *elevator_merge_fn;
47 elevator_merged_fn *elevator_merged_fn;
48 elevator_merge_req_fn *elevator_merge_req_fn;
49 elevator_allow_merge_fn *elevator_allow_merge_fn;
50 elevator_bio_merged_fn *elevator_bio_merged_fn;
51
52 elevator_dispatch_fn *elevator_dispatch_fn;
53 elevator_add_req_fn *elevator_add_req_fn;
54 elevator_activate_req_fn *elevator_activate_req_fn;
55 elevator_deactivate_req_fn *elevator_deactivate_req_fn;
56
57 elevator_completed_req_fn *elevator_completed_req_fn;
58
59 elevator_request_list_fn *elevator_former_req_fn;
60 elevator_request_list_fn *elevator_latter_req_fn;
61
62 elevator_init_icq_fn *elevator_init_icq_fn; /* see iocontext.h */
63 elevator_exit_icq_fn *elevator_exit_icq_fn; /* ditto */
64
65 elevator_set_req_fn *elevator_set_req_fn;
66 elevator_put_req_fn *elevator_put_req_fn;
67
68 elevator_may_queue_fn *elevator_may_queue_fn;
69
70 elevator_init_fn *elevator_init_fn;
71 elevator_exit_fn *elevator_exit_fn;
72 elevator_registered_fn *elevator_registered_fn;
73 };
74
75 #define ELV_NAME_MAX (16)
76
77 struct elv_fs_entry {
78 struct attribute attr;
79 ssize_t (*show)(struct elevator_queue *, char *);
80 ssize_t (*store)(struct elevator_queue *, const char *, size_t);
81 };
82
83 /*
84 * identifies an elevator type, such as AS or deadline
85 */
86 struct elevator_type
87 {
88 /* managed by elevator core */
89 struct kmem_cache *icq_cache;
90
91 /* fields provided by elevator implementation */
92 struct elevator_ops ops;
93 size_t icq_size; /* see iocontext.h */
94 size_t icq_align; /* ditto */
95 struct elv_fs_entry *elevator_attrs;
96 char elevator_name[ELV_NAME_MAX];
97 struct module *elevator_owner;
98
99 /* managed by elevator core */
100 char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */
101 struct list_head list;
102 };
103
104 #define ELV_HASH_BITS 6
105
106 /*
107 * each queue has an elevator_queue associated with it
108 */
109 struct elevator_queue
110 {
111 struct elevator_type *type;
112 void *elevator_data;
113 struct kobject kobj;
114 struct mutex sysfs_lock;
115 unsigned int registered:1;
116 DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
117 };
118
119 /*
120 * block elevator interface
121 */
122 extern void elv_dispatch_sort(struct request_queue *, struct request *);
123 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
124 extern void elv_add_request(struct request_queue *, struct request *, int);
125 extern void __elv_add_request(struct request_queue *, struct request *, int);
126 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
127 extern void elv_merge_requests(struct request_queue *, struct request *,
128 struct request *);
129 extern void elv_merged_request(struct request_queue *, struct request *, int);
130 extern void elv_bio_merged(struct request_queue *q, struct request *,
131 struct bio *);
132 extern void elv_requeue_request(struct request_queue *, struct request *);
133 extern struct request *elv_former_request(struct request_queue *, struct request *);
134 extern struct request *elv_latter_request(struct request_queue *, struct request *);
135 extern int elv_register_queue(struct request_queue *q);
136 extern void elv_unregister_queue(struct request_queue *q);
137 extern int elv_may_queue(struct request_queue *, int);
138 extern void elv_completed_request(struct request_queue *, struct request *);
139 extern int elv_set_request(struct request_queue *q, struct request *rq,
140 struct bio *bio, gfp_t gfp_mask);
141 extern void elv_put_request(struct request_queue *, struct request *);
142 extern void elv_drain_elevator(struct request_queue *);
143
144 /*
145 * io scheduler registration
146 */
147 extern void __init load_default_elevator_module(void);
148 extern int elv_register(struct elevator_type *);
149 extern void elv_unregister(struct elevator_type *);
150
151 /*
152 * io scheduler sysfs switching
153 */
154 extern ssize_t elv_iosched_show(struct request_queue *, char *);
155 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
156
157 extern int elevator_init(struct request_queue *, char *);
158 extern void elevator_exit(struct elevator_queue *);
159 extern int elevator_change(struct request_queue *, const char *);
160 extern bool elv_rq_merge_ok(struct request *, struct bio *);
161 extern struct elevator_queue *elevator_alloc(struct request_queue *,
162 struct elevator_type *);
163
164 /*
165 * Helper functions.
166 */
167 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
168 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
169
170 /*
171 * rb support functions.
172 */
173 extern void elv_rb_add(struct rb_root *, struct request *);
174 extern void elv_rb_del(struct rb_root *, struct request *);
175 extern struct request *elv_rb_find(struct rb_root *, sector_t);
176
177 /*
178 * Return values from elevator merger
179 */
180 #define ELEVATOR_NO_MERGE 0
181 #define ELEVATOR_FRONT_MERGE 1
182 #define ELEVATOR_BACK_MERGE 2
183
184 /*
185 * Insertion selection
186 */
187 #define ELEVATOR_INSERT_FRONT 1
188 #define ELEVATOR_INSERT_BACK 2
189 #define ELEVATOR_INSERT_SORT 3
190 #define ELEVATOR_INSERT_REQUEUE 4
191 #define ELEVATOR_INSERT_FLUSH 5
192 #define ELEVATOR_INSERT_SORT_MERGE 6
193
194 /*
195 * return values from elevator_may_queue_fn
196 */
197 enum {
198 ELV_MQUEUE_MAY,
199 ELV_MQUEUE_NO,
200 ELV_MQUEUE_MUST,
201 };
202
203 #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq))
204 #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
205
206 #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
207 #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
208
209 #else /* CONFIG_BLOCK */
210
load_default_elevator_module(void)211 static inline void load_default_elevator_module(void) { }
212
213 #endif /* CONFIG_BLOCK */
214 #endif
215