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