Line data Source code
1 : #ifndef _LINUX_ELEVATOR_H
2 : #define _LINUX_ELEVATOR_H
3 :
4 : #include <linux/percpu.h>
5 :
6 : #ifdef CONFIG_BLOCK
7 :
8 1 : typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
9 : struct bio *);
10 :
11 1 : typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
12 :
13 1 : typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
14 :
15 1 : typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
16 :
17 1 : typedef int (elevator_dispatch_fn) (struct request_queue *, int);
18 :
19 1 : typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
20 1 : typedef int (elevator_queue_empty_fn) (struct request_queue *);
21 1 : typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
22 1 : typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
23 1 : typedef int (elevator_may_queue_fn) (struct request_queue *, int);
24 :
25 1 : typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
26 1 : typedef void (elevator_put_req_fn) (struct request *);
27 1 : typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
28 1 : typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
29 :
30 1 : typedef void *(elevator_init_fn) (struct request_queue *);
31 1 : typedef void (elevator_exit_fn) (struct elevator_queue *);
32 1 :
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 1 :
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 1 :
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 1 :
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
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