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
43 struct 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
75 struct 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 */
84 struct 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 */
107 struct 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 */
120 extern void elv_dispatch_sort(struct request_queue *, struct request *);
121 extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
122 extern void elv_add_request(struct request_queue *, struct request *, int);
123 extern void __elv_add_request(struct request_queue *, struct request *, int);
124 extern int elv_merge(struct request_queue *, struct request **, struct bio *);
125 extern void elv_merge_requests(struct request_queue *, struct request *,
126 struct request *);
127 extern void elv_merged_request(struct request_queue *, struct request *, int);
128 extern void elv_bio_merged(struct request_queue *q, struct request *,
129 struct bio *);
130 extern void elv_requeue_request(struct request_queue *, struct request *);
131 extern struct request *elv_former_request(struct request_queue *, struct request *);
132 extern struct request *elv_latter_request(struct request_queue *, struct request *);
133 extern int elv_register_queue(struct request_queue *q);
134 extern void elv_unregister_queue(struct request_queue *q);
135 extern int elv_may_queue(struct request_queue *, int);
136 extern void elv_completed_request(struct request_queue *, struct request *);
137 extern int elv_set_request(struct request_queue *q, struct request *rq,
138 struct bio *bio, gfp_t gfp_mask);
139 extern void elv_put_request(struct request_queue *, struct request *);
140 extern void elv_drain_elevator(struct request_queue *);
141
142 /*
143 * io scheduler registration
144 */
145 extern void __init load_default_elevator_module(void);
146 extern int elv_register(struct elevator_type *);
147 extern void elv_unregister(struct elevator_type *);
148
149 /*
150 * io scheduler sysfs switching
151 */
152 extern ssize_t elv_iosched_show(struct request_queue *, char *);
153 extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
154
155 extern int elevator_init(struct request_queue *, char *);
156 extern void elevator_exit(struct elevator_queue *);
157 extern int elevator_change(struct request_queue *, const char *);
158 extern bool elv_rq_merge_ok(struct request *, struct bio *);
159 extern struct elevator_queue *elevator_alloc(struct request_queue *,
160 struct elevator_type *);
161
162 /*
163 * Helper functions.
164 */
165 extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
166 extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
167
168 /*
169 * rb support functions.
170 */
171 extern void elv_rb_add(struct rb_root *, struct request *);
172 extern void elv_rb_del(struct rb_root *, struct request *);
173 extern 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 */
195 enum {
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
load_default_elevator_module(void)209 static inline void load_default_elevator_module(void) { }
210
211 #endif /* CONFIG_BLOCK */
212 #endif
213