include/linux/cleancache.h

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