include/linux/cleancache.h

   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  */
  21 struct cleancache_filekey {
  22         union {
  23                 ino_t ino;
  24                 __u32 fh[CLEANCACHE_KEY_MAX];
  25                 u32 key[CLEANCACHE_KEY_MAX];
  26         } u;
  27 };
  28
  29 struct 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
  41 extern int cleancache_register_ops(const struct cleancache_ops *ops);
  42 extern void __cleancache_init_fs(struct super_block *);
  43 extern void __cleancache_init_shared_fs(struct super_block *);
  44 extern int  __cleancache_get_page(struct page *);
  45 extern void __cleancache_put_page(struct page *);
  46 extern void __cleancache_invalidate_page(struct address_space *, struct page *);
  47 extern void __cleancache_invalidate_inode(struct address_space *);
  48 extern void __cleancache_invalidate_fs(struct super_block *);
  49
  50 #ifdef CONFIG_CLEANCACHE
  51 #define cleancache_enabled (1)
  52 static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
  53 {
  54         return mapping->host->i_sb->cleancache_poolid >= 0;
  55 }
  56 static 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
  79 static inline void cleancache_init_fs(struct super_block *sb)
  80 {
  81         if (cleancache_enabled)
  82                 __cleancache_init_fs(sb);
  83 }
  84
  85 static inline void cleancache_init_shared_fs(struct super_block *sb)
  86 {
  87         if (cleancache_enabled)
  88                 __cleancache_init_shared_fs(sb);
  89 }
  90
  91 static 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
  98 static inline void cleancache_put_page(struct page *page)
  99 {
 100         if (cleancache_enabled && cleancache_fs_enabled(page))
 101                 __cleancache_put_page(page);
 102 }
 103
 104 static 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
 112 static 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
 118 static 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 */