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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