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 : #include "blk-mq.h"
8 :
9 : struct io_cq;
10 : struct elevator_type;
11 : struct blk_mq_debugfs_attr;
12 :
13 : /*
14 : * Return values from elevator merger
15 : */
16 : enum elv_merge {
17 : ELEVATOR_NO_MERGE = 0,
18 : ELEVATOR_FRONT_MERGE = 1,
19 : ELEVATOR_BACK_MERGE = 2,
20 : ELEVATOR_DISCARD_MERGE = 3,
21 : };
22 :
23 : struct blk_mq_alloc_data;
24 : struct blk_mq_hw_ctx;
25 :
26 : struct elevator_mq_ops {
27 : int (*init_sched)(struct request_queue *, struct elevator_type *);
28 : void (*exit_sched)(struct elevator_queue *);
29 : int (*init_hctx)(struct blk_mq_hw_ctx *, unsigned int);
30 : void (*exit_hctx)(struct blk_mq_hw_ctx *, unsigned int);
31 : void (*depth_updated)(struct blk_mq_hw_ctx *);
32 :
33 : bool (*allow_merge)(struct request_queue *, struct request *, struct bio *);
34 : bool (*bio_merge)(struct request_queue *, struct bio *, unsigned int);
35 : int (*request_merge)(struct request_queue *q, struct request **, struct bio *);
36 : void (*request_merged)(struct request_queue *, struct request *, enum elv_merge);
37 : void (*requests_merged)(struct request_queue *, struct request *, struct request *);
38 : void (*limit_depth)(blk_opf_t, struct blk_mq_alloc_data *);
39 : void (*prepare_request)(struct request *);
40 : void (*finish_request)(struct request *);
41 : void (*insert_requests)(struct blk_mq_hw_ctx *hctx, struct list_head *list,
42 : blk_insert_t flags);
43 : struct request *(*dispatch_request)(struct blk_mq_hw_ctx *);
44 : bool (*has_work)(struct blk_mq_hw_ctx *);
45 : void (*completed_request)(struct request *, u64);
46 : void (*requeue_request)(struct request *);
47 : struct request *(*former_request)(struct request_queue *, struct request *);
48 : struct request *(*next_request)(struct request_queue *, struct request *);
49 : void (*init_icq)(struct io_cq *);
50 : void (*exit_icq)(struct io_cq *);
51 : };
52 :
53 : #define ELV_NAME_MAX (16)
54 :
55 : struct elv_fs_entry {
56 : struct attribute attr;
57 : ssize_t (*show)(struct elevator_queue *, char *);
58 : ssize_t (*store)(struct elevator_queue *, const char *, size_t);
59 : };
60 :
61 : /*
62 : * identifies an elevator type, such as AS or deadline
63 : */
64 : struct elevator_type
65 : {
66 : /* managed by elevator core */
67 : struct kmem_cache *icq_cache;
68 :
69 : /* fields provided by elevator implementation */
70 : struct elevator_mq_ops ops;
71 :
72 : size_t icq_size; /* see iocontext.h */
73 : size_t icq_align; /* ditto */
74 : struct elv_fs_entry *elevator_attrs;
75 : const char *elevator_name;
76 : const char *elevator_alias;
77 : const unsigned int elevator_features;
78 : struct module *elevator_owner;
79 : #ifdef CONFIG_BLK_DEBUG_FS
80 : const struct blk_mq_debugfs_attr *queue_debugfs_attrs;
81 : const struct blk_mq_debugfs_attr *hctx_debugfs_attrs;
82 : #endif
83 :
84 : /* managed by elevator core */
85 : char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */
86 : struct list_head list;
87 : };
88 :
89 : static inline bool elevator_tryget(struct elevator_type *e)
90 : {
91 : return try_module_get(e->elevator_owner);
92 : }
93 :
94 : static inline void __elevator_get(struct elevator_type *e)
95 : {
96 0 : __module_get(e->elevator_owner);
97 : }
98 :
99 : static inline void elevator_put(struct elevator_type *e)
100 : {
101 0 : module_put(e->elevator_owner);
102 : }
103 :
104 : #define ELV_HASH_BITS 6
105 :
106 : void elv_rqhash_del(struct request_queue *q, struct request *rq);
107 : void elv_rqhash_add(struct request_queue *q, struct request *rq);
108 : void elv_rqhash_reposition(struct request_queue *q, struct request *rq);
109 : struct request *elv_rqhash_find(struct request_queue *q, sector_t offset);
110 :
111 : /*
112 : * each queue has an elevator_queue associated with it
113 : */
114 : struct elevator_queue
115 : {
116 : struct elevator_type *type;
117 : void *elevator_data;
118 : struct kobject kobj;
119 : struct mutex sysfs_lock;
120 : unsigned long flags;
121 : DECLARE_HASHTABLE(hash, ELV_HASH_BITS);
122 : };
123 :
124 : #define ELEVATOR_FLAG_REGISTERED 0
125 : #define ELEVATOR_FLAG_DISABLE_WBT 1
126 :
127 : /*
128 : * block elevator interface
129 : */
130 : extern enum elv_merge elv_merge(struct request_queue *, struct request **,
131 : struct bio *);
132 : extern void elv_merge_requests(struct request_queue *, struct request *,
133 : struct request *);
134 : extern void elv_merged_request(struct request_queue *, struct request *,
135 : enum elv_merge);
136 : extern bool elv_attempt_insert_merge(struct request_queue *, struct request *,
137 : struct list_head *);
138 : extern struct request *elv_former_request(struct request_queue *, struct request *);
139 : extern struct request *elv_latter_request(struct request_queue *, struct request *);
140 : void elevator_init_mq(struct request_queue *q);
141 :
142 : /*
143 : * io scheduler registration
144 : */
145 : extern int elv_register(struct elevator_type *);
146 : extern void elv_unregister(struct elevator_type *);
147 :
148 : /*
149 : * io scheduler sysfs switching
150 : */
151 : extern ssize_t elv_iosched_show(struct request_queue *, char *);
152 : extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
153 :
154 : extern bool elv_bio_merge_ok(struct request *, struct bio *);
155 : extern struct elevator_queue *elevator_alloc(struct request_queue *,
156 : struct elevator_type *);
157 :
158 : /*
159 : * Helper functions.
160 : */
161 : extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
162 : extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
163 :
164 : /*
165 : * rb support functions.
166 : */
167 : extern void elv_rb_add(struct rb_root *, struct request *);
168 : extern void elv_rb_del(struct rb_root *, struct request *);
169 : extern struct request *elv_rb_find(struct rb_root *, sector_t);
170 :
171 : /*
172 : * Insertion selection
173 : */
174 : #define ELEVATOR_INSERT_FRONT 1
175 : #define ELEVATOR_INSERT_BACK 2
176 : #define ELEVATOR_INSERT_SORT 3
177 : #define ELEVATOR_INSERT_REQUEUE 4
178 : #define ELEVATOR_INSERT_FLUSH 5
179 : #define ELEVATOR_INSERT_SORT_MERGE 6
180 :
181 : #define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
182 :
183 : #define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
184 : #define rq_fifo_clear(rq) list_del_init(&(rq)->queuelist)
185 :
186 : #endif /* _ELEVATOR_H */
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