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 */
20struct cleancache_filekey {
21	union {
22		ino_t ino;
23		__u32 fh[CLEANCACHE_KEY_MAX];
24		u32 key[CLEANCACHE_KEY_MAX];
25	} u;
26};
27
28struct cleancache_ops {
29	int (*init_fs)(size_t);
30	int (*init_shared_fs)(char *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
40extern int cleancache_register_ops(struct cleancache_ops *ops);
41extern void __cleancache_init_fs(struct super_block *);
42extern void __cleancache_init_shared_fs(struct super_block *);
43extern int  __cleancache_get_page(struct page *);
44extern void __cleancache_put_page(struct page *);
45extern void __cleancache_invalidate_page(struct address_space *, struct page *);
46extern void __cleancache_invalidate_inode(struct address_space *);
47extern void __cleancache_invalidate_fs(struct super_block *);
48
49#ifdef CONFIG_CLEANCACHE
50#define cleancache_enabled (1)
51static inline bool cleancache_fs_enabled(struct page *page)
52{
53	return page->mapping->host->i_sb->cleancache_poolid >= 0;
54}
55static inline bool cleancache_fs_enabled_mapping(struct address_space *mapping)
56{
57	return mapping->host->i_sb->cleancache_poolid >= 0;
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
78static inline void cleancache_init_fs(struct super_block *sb)
79{
80	if (cleancache_enabled)
81		__cleancache_init_fs(sb);
82}
83
84static inline void cleancache_init_shared_fs(struct super_block *sb)
85{
86	if (cleancache_enabled)
87		__cleancache_init_shared_fs(sb);
88}
89
90static inline int cleancache_get_page(struct page *page)
91{
92	int ret = -1;
93
94	if (cleancache_enabled && cleancache_fs_enabled(page))
95		ret = __cleancache_get_page(page);
96	return ret;
97}
98
99static inline void cleancache_put_page(struct page *page)
100{
101	if (cleancache_enabled && cleancache_fs_enabled(page))
102		__cleancache_put_page(page);
103}
104
105static inline void cleancache_invalidate_page(struct address_space *mapping,
106					struct page *page)
107{
108	/* careful... page->mapping is NULL sometimes when this is called */
109	if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
110		__cleancache_invalidate_page(mapping, page);
111}
112
113static inline void cleancache_invalidate_inode(struct address_space *mapping)
114{
115	if (cleancache_enabled && cleancache_fs_enabled_mapping(mapping))
116		__cleancache_invalidate_inode(mapping);
117}
118
119static inline void cleancache_invalidate_fs(struct super_block *sb)
120{
121	if (cleancache_enabled)
122		__cleancache_invalidate_fs(sb);
123}
124
125#endif /* _LINUX_CLEANCACHE_H */
126