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