1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_CLEANCACHE_H
3#define _LINUX_CLEANCACHE_H
4
5#include <linux/fs.h>
6#include <linux/exportfs.h>
7#include <linux/mm.h>
8
9#define CLEANCACHE_NO_POOL -1
10#define CLEANCACHE_NO_BACKEND -2
11#define CLEANCACHE_NO_BACKEND_SHARED -3
12
13#define CLEANCACHE_KEY_MAX 6
14
15/*
16 * cleancache requires every file with a page in cleancache to have a
17 * unique key unless/until the file is removed/truncated. For some
18 * filesystems, the inode number is unique, but for "modern" filesystems
19 * an exportable filehandle is required (see exportfs.h)
20 */
21struct cleancache_filekey {
22 union {
23 ino_t ino;
24 __u32 fh[CLEANCACHE_KEY_MAX];
25 u32 key[CLEANCACHE_KEY_MAX];
26 } u;
27};
28
29struct cleancache_ops {
30 int (*init_fs)(size_t);
31 int (*init_shared_fs)(uuid_t *uuid, size_t);
32 int (*get_page)(int, struct cleancache_filekey,
33 pgoff_t, struct page *);
34 void (*put_page)(int, struct cleancache_filekey,
35 pgoff_t, struct page *);
36 void (*invalidate_page)(int, struct cleancache_filekey, pgoff_t);
37 void (*invalidate_inode)(int, struct cleancache_filekey);
38 void (*invalidate_fs)(int);
39};
40
41extern int cleancache_register_ops(const struct cleancache_ops *ops);
42extern void __cleancache_init_fs(struct super_block *);
43extern void __cleancache_init_shared_fs(struct super_block *);
44extern int __cleancache_get_page(struct page *);
45extern void __cleancache_put_page(struct page *);
46extern void __cleancache_invalidate_page(struct address_space *, struct page *);
47extern void __cleancache_invalidate_inode(struct address_space *);
48extern void __cleancache_invalidate_fs(struct super_block *);
49
50#ifdef CONFIG_CLEANCACHE
51#define cleancache_enabled (1)
52static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
53{
54 return mapping->host->i_sb->cleancache_poolid >= 0;
55}
56static inline bool cleancache_fs_enabled(struct page *page)
57{
58 return cleancache_fs_enabled_mapping(page->mapping);
59}
60#else
61#define cleancache_enabled (0)
62#define cleancache_fs_enabled(_page) (0)
63#define cleancache_fs_enabled_mapping(_page) (0)
64#endif
65
66/*
67 * The shim layer provided by these inline functions allows the compiler
68 * to reduce all cleancache hooks to nothingness if CONFIG_CLEANCACHE
69 * is disabled, to a single global variable check if CONFIG_CLEANCACHE
70 * is enabled but no cleancache "backend" has dynamically enabled it,
71 * and, for the most frequent cleancache ops, to a single global variable
72 * check plus a superblock element comparison if CONFIG_CLEANCACHE is enabled
73 * and a cleancache backend has dynamically enabled cleancache, but the
74 * filesystem referenced by that cleancache op has not enabled cleancache.
75 * As a result, CONFIG_CLEANCACHE can be enabled by default with essentially
76 * no measurable performance impact.
77 */
78
79static inline void cleancache_init_fs(struct super_block *sb)
80{
81 if (cleancache_enabled)
82 __cleancache_init_fs(sb);
83}
84
85static inline void cleancache_init_shared_fs(struct super_block *sb)
86{
87 if (cleancache_enabled)
88 __cleancache_init_shared_fs(sb);
89}
90
91static inline int cleancache_get_page(struct page *page)
92{
93 if (cleancache_enabled && cleancache_fs_enabled(page))
94 return __cleancache_get_page(page);
95 return -1;
96}
97
98static inline void cleancache_put_page(struct page *page)
99{
100 if (cleancache_enabled && cleancache_fs_enabled(page))
101 __cleancache_put_page(page);
102}
103
104static inline void cleancache_invalidate_page(struct address_space *mapping,
105 struct page *page)
106{
107 /* careful... page->mapping is NULL sometimes when this is called */
108 if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
109 __cleancache_invalidate_page(mapping, page);
110}
111
112static inline void cleancache_invalidate_inode(struct address_space *mapping)
113{
114 if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
115 __cleancache_invalidate_inode(mapping);
116}
117
118static inline void cleancache_invalidate_fs(struct super_block *sb)
119{
120 if (cleancache_enabled)
121 __cleancache_invalidate_fs(sb);
122}
123
124#endif /* _LINUX_CLEANCACHE_H */
125