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_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  */
  16 struct cleancache_filekey {
  17         union {
  18                 ino_t ino;
  19                 __u32 fh[CLEANCACHE_KEY_MAX];
  20                 u32 key[CLEANCACHE_KEY_MAX];
  21         } u;
  22 };
  23
  24 struct cleancache_ops {
  25         int (*init_fs)(size_t);
  26         int (*init_shared_fs)(char *uuid, size_t);
  27         int (*get_page)(int, struct cleancache_filekey,
  28                         pgoff_t, struct page *);
  29         void (*put_page)(int, struct cleancache_filekey,
  30                         pgoff_t, struct page *);
  31         /*
  32          * NOTE: per akpm, flush_page, flush_inode and flush_fs will be
  33          * renamed to invalidate_* in a later commit in which all
  34          * dependencies (i.e Xen, zcache) will be renamed simultaneously
  35          */
  36         void (*flush_page)(int, struct cleancache_filekey, pgoff_t);
  37         void (*flush_inode)(int, struct cleancache_filekey);
  38         void (*flush_fs)(int);
  39 };
  40
  41 extern struct cleancache_ops
  42         cleancache_register_ops(struct cleancache_ops *ops);
  43 extern void __cleancache_init_fs(struct super_block *);
  44 extern void __cleancache_init_shared_fs(char *, struct super_block *);
  45 extern int  __cleancache_get_page(struct page *);
  46 extern void __cleancache_put_page(struct page *);
  47 extern void __cleancache_invalidate_page(struct address_space *, struct page *);
  48 extern void __cleancache_invalidate_inode(struct address_space *);
  49 extern void __cleancache_invalidate_fs(struct super_block *);
  50 extern int cleancache_enabled;
  51
  52 #ifdef CONFIG_CLEANCACHE
  53 static inline bool cleancache_fs_enabled(struct page *page)
  54 {
  55         return page->mapping->host->i_sb->cleancache_poolid >= 0;
  56 }
  57 static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
  58 {
  59         return mapping->host->i_sb->cleancache_poolid >= 0;
  60 }
  61 #else
  62 #define cleancache_enabled (0)
  63 #define cleancache_fs_enabled(_page) (0)
  64 #define cleancache_fs_enabled_mapping(_page) (0)
  65 #endif
  66
  67 /*
  68  * The shim layer provided by these inline functions allows the compiler
  69  * to reduce all cleancache hooks to nothingness if CONFIG_CLEANCACHE
  70  * is disabled, to a single global variable check if CONFIG_CLEANCACHE
  71  * is enabled but no cleancache "backend" has dynamically enabled it,
  72  * and, for the most frequent cleancache ops, to a single global variable
  73  * check plus a superblock element comparison if CONFIG_CLEANCACHE is enabled
  74  * and a cleancache backend has dynamically enabled cleancache, but the
  75  * filesystem referenced by that cleancache op has not enabled cleancache.
  76  * As a result, CONFIG_CLEANCACHE can be enabled by default with essentially
  77  * no measurable performance impact.
  78  */
  79
  80 static inline void cleancache_init_fs(struct super_block *sb)
  81 {
  82         if (cleancache_enabled)
  83                 __cleancache_init_fs(sb);
  84 }
  85
  86 static inline void cleancache_init_shared_fs(char *uuid, struct super_block *sb)
  87 {
  88         if (cleancache_enabled)
  89                 __cleancache_init_shared_fs(uuid, sb);
  90 }
  91
  92 static inline int cleancache_get_page(struct page *page)
  93 {
  94         int ret = -1;
  95
  96         if (cleancache_enabled && cleancache_fs_enabled(page))
  97                 ret = __cleancache_get_page(page);
  98         return ret;
  99 }
 100
 101 static inline void cleancache_put_page(struct page *page)
 102 {
 103         if (cleancache_enabled && cleancache_fs_enabled(page))
 104                 __cleancache_put_page(page);
 105 }
 106
 107 static inline void cleancache_invalidate_page(struct address_space *mapping,
 108                                         struct page *page)
 109 {
 110         /* careful... page->mapping is NULL sometimes when this is called */
 111         if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
 112                 __cleancache_invalidate_page(mapping, page);
 113 }
 114
 115 static inline void cleancache_invalidate_inode(struct address_space *mapping)
 116 {
 117         if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
 118                 __cleancache_invalidate_inode(mapping);
 119 }
 120
 121 static inline void cleancache_invalidate_fs(struct super_block *sb)
 122 {
 123         if (cleancache_enabled)
 124                 __cleancache_invalidate_fs(sb);
 125 }
 126
 127 #endif /* _LINUX_CLEANCACHE_H */