Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _ELEVATOR_H
3 : #define _ELEVATOR_H
4 :
5 : #include <linux/percpu.h>
6 : #include <linux/hashtable.h>
7 :
8 : struct io_cq;
9 : struct elevator_type;
10 : struct blk_mq_debugfs_attr;
11 :
12 : /*
13 : * Return values from elevator merger
14 : */
15 : enum elv_merge {
16 : ELEVATOR_NO_MERGE = 0,
17 : ELEVATOR_FRONT_MERGE = 1,
18 : ELEVATOR_BACK_MERGE = 2,
19 : ELEVATOR_DISCARD_MERGE = 3,
20 : };
21 :
22 : struct blk_mq_alloc_data;
23 : struct blk_mq_hw_ctx;
24 :
25 : struct elevator_mq_ops {
26 : int (*init_sched)(struct request_queue *, struct elevator_type *);
27 : void (*exit_sched)(struct elevator_queue *);
28 : int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
29 : void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
30 : void (*depth_updated)(struct blk_mq_hw_ctx *);
31 :
32 : bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
33 : bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
34 : int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
35 : void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
36 : void (*requests_merged)(struct request_queue *, struct request *, struct request *);
37 : void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
38 : void (*prepare_request)(struct request *);
39 : void (*finish_request)(struct request *);
40 : void (*insert_requests)(struct blk_mq_hw_ctx *, struct list_head *, bool);
41 : struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
42 : bool (*has_work)(struct blk_mq_hw_ctx *);
43 : void (*completed_request)(struct request *, u64);
44 : void (*requeue_request)(struct request *);
45 : struct request *(*former_request)(struct request_queue *, struct request *);
46 : struct request *(*next_request)(struct request_queue *, struct request *);
47 : void (*init_icq)(struct io_cq *);
48 : void (*exit_icq)(struct io_cq *);
49 : };
50 :
51 : #define ELV_NAME_MAX (16)
52 :
53 : struct elv_fs_entry {
54 : struct attribute attr;
55 : ssize_t (*show)(struct elevator_queue *, char *);
56 : ssize_t (*store)(struct elevator_queue *, const char *, size_t);
57 : };
58 :
59 : /*
60 : * identifies an elevator type, such as AS or deadline
61 : */
62 : struct elevator_type
63 : {
64 : /* managed by elevator core */
65 : struct kmem_cache *icq_cache;
66 :
67 : /* fields provided by elevator implementation */
68 : struct elevator_mq_ops ops;
69 :
70 : size_t icq_size; /* see iocontext.h */
71 : size_t icq_align; /* ditto */
72 : struct elv_fs_entry *elevator_attrs;
73 : const char *elevator_name;
74 : const char *elevator_alias;
75 : const unsigned int elevator_features;
76 : struct module *elevator_owner;
77 : #ifdef CONFIG_BLK_DEBUG_FS
78 : const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
79 : const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
80 : #endif
81 :
82 : /* managed by elevator core */
83 : char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
84 : struct list_head list;
85 : };
86 :
87 : static inline bool elevator_tryget(struct elevator_type *e)
88 : {
89 : return try_module_get(e->elevator_owner);
90 : }
91 :
92 : static inline void __elevator_get(struct elevator_type *e)
93 : {
94 0 : __module_get(e->elevator_owner);
95 : }
96 :
97 : static inline void elevator_put(struct elevator_type *e)
98 : {
99 0 : module_put(e->elevator_owner);
100 : }
101 :
102 : #define ELV_HASH_BITS 6
103 :
104 : void elv_rqhash_del(struct request_queue *q, struct request *rq);
105 : void elv_rqhash_add(struct request_queue *q, struct request *rq);
106 : void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
107 : struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
108 :
109 : /*
110 : * each queue has an elevator_queue associated with it
111 : */
112 : struct elevator_queue
113 : {
114 : struct elevator_type *type;
115 : void *elevator_data;
116 : struct kobject kobj;
117 : struct mutex sysfs_lock;
118 : unsigned long flags;
119 : DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
120 : };
121 :
122 : #define ELEVATOR_FLAG_REGISTERED 0
123 : #define ELEVATOR_FLAG_DISABLE_WBT 1
124 :
125 : /*
126 : * block elevator interface
127 : */
128 : extern enum elv_merge elv_merge(struct request_queue *, struct request **,
129 : struct bio *);
130 : extern void elv_merge_requests(struct request_queue *, struct request *,
131 : struct request *);
132 : extern void elv_merged_request(struct request_queue *, struct request *,
133 : enum elv_merge);
134 : extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
135 : struct list_head *);
136 : extern struct request *elv_former_request(struct request_queue *, struct request *);
137 : extern struct request *elv_latter_request(struct request_queue *, struct request *);
138 : void elevator_init_mq(struct request_queue *q);
139 :
140 : /*
141 : * io scheduler registration
142 : */
143 : extern int elv_register(struct elevator_type *);
144 : extern void elv_unregister(struct elevator_type *);
145 :
146 : /*
147 : * io scheduler sysfs switching
148 : */
149 : extern ssize_t elv_iosched_show(struct request_queue *, char *);
150 : extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
151 :
152 : extern bool elv_bio_merge_ok(struct request *, struct bio *);
153 : extern struct elevator_queue *elevator_alloc(struct request_queue *,
154 : struct elevator_type *);
155 :
156 : /*
157 : * Helper functions.
158 : */
159 : extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
160 : extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
161 :
162 : /*
163 : * rb support functions.
164 : */
165 : extern void elv_rb_add(struct rb_root *, struct request *);
166 : extern void elv_rb_del(struct rb_root *, struct request *);
167 : extern struct request *elv_rb_find(struct rb_root *, sector_t);
168 :
169 : /*
170 : * Insertion selection
171 : */
172 : #define ELEVATOR_INSERT_FRONT 1
173 : #define ELEVATOR_INSERT_BACK 2
174 : #define ELEVATOR_INSERT_SORT 3
175 : #define ELEVATOR_INSERT_REQUEUE 4
176 : #define ELEVATOR_INSERT_FLUSH 5
177 : #define ELEVATOR_INSERT_SORT_MERGE 6
178 :
179 : #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
180 :
181 : #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
182 : #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
183 :
184 : #endif /* _ELEVATOR_H */
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