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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_abort_queue(struct request_queue *); |
137 | extern void elv_completed_request(struct request_queue *, struct request *); |
138 | extern int elv_set_request(struct request_queue *q, struct request *rq, |
139 | struct bio *bio, gfp_t gfp_mask); |
140 | extern void elv_put_request(struct request_queue *, struct request *); |
141 | extern void elv_drain_elevator(struct request_queue *); |
142 | |
143 | /* |
144 | * io scheduler registration |
145 | */ |
146 | extern void __init load_default_elevator_module(void); |
147 | extern int elv_register(struct elevator_type *); |
148 | extern void elv_unregister(struct elevator_type *); |
149 | |
150 | /* |
151 | * io scheduler sysfs switching |
152 | */ |
153 | extern ssize_t elv_iosched_show(struct request_queue *, char *); |
154 | extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t); |
155 | |
156 | extern int elevator_init(struct request_queue *, char *); |
157 | extern void elevator_exit(struct elevator_queue *); |
158 | extern int elevator_change(struct request_queue *, const char *); |
159 | extern bool elv_rq_merge_ok(struct request *, struct bio *); |
160 | extern struct elevator_queue *elevator_alloc(struct request_queue *, |
161 | struct elevator_type *); |
162 | |
163 | /* |
164 | * Helper functions. |
165 | */ |
166 | extern struct request *elv_rb_former_request(struct request_queue *, struct request *); |
167 | extern struct request *elv_rb_latter_request(struct request_queue *, struct request *); |
168 | |
169 | /* |
170 | * rb support functions. |
171 | */ |
172 | extern void elv_rb_add(struct rb_root *, struct request *); |
173 | extern void elv_rb_del(struct rb_root *, struct request *); |
174 | extern struct request *elv_rb_find(struct rb_root *, sector_t); |
175 | |
176 | /* |
177 | * Return values from elevator merger |
178 | */ |
179 | #define ELEVATOR_NO_MERGE 0 |
180 | #define ELEVATOR_FRONT_MERGE 1 |
181 | #define ELEVATOR_BACK_MERGE 2 |
182 | |
183 | /* |
184 | * Insertion selection |
185 | */ |
186 | #define ELEVATOR_INSERT_FRONT 1 |
187 | #define ELEVATOR_INSERT_BACK 2 |
188 | #define ELEVATOR_INSERT_SORT 3 |
189 | #define ELEVATOR_INSERT_REQUEUE 4 |
190 | #define ELEVATOR_INSERT_FLUSH 5 |
191 | #define ELEVATOR_INSERT_SORT_MERGE 6 |
192 | |
193 | /* |
194 | * return values from elevator_may_queue_fn |
195 | */ |
196 | enum { |
197 | ELV_MQUEUE_MAY, |
198 | ELV_MQUEUE_NO, |
199 | ELV_MQUEUE_MUST, |
200 | }; |
201 | |
202 | #define rq_end_sector(rq) (blk_rq_pos(rq) + blk_rq_sectors(rq)) |
203 | #define rb_entry_rq(node) rb_entry((node), struct request, rb_node) |
204 | |
205 | /* |
206 | * Hack to reuse the csd.list list_head as the fifo time holder while |
207 | * the request is in the io scheduler. Saves an unsigned long in rq. |
208 | */ |
209 | #define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next) |
210 | #define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp)) |
211 | #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist) |
212 | #define rq_fifo_clear(rq) do { \ |
213 | list_del_init(&(rq)->queuelist); \ |
214 | INIT_LIST_HEAD(&(rq)->csd.list); \ |
215 | } while (0) |
216 | |
217 | #else /* CONFIG_BLOCK */ |
218 | |
219 | static inline void load_default_elevator_module(void) { } |
220 | |
221 | #endif /* CONFIG_BLOCK */ |
222 | #endif |
223 |
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