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