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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_FRONTSWAP_H
3#define _LINUX_FRONTSWAP_H
4
5#include <linux/swap.h>
6#include <linux/mm.h>
7#include <linux/bitops.h>
8#include <linux/jump_label.h>
9
10/*
11 * Return code to denote that requested number of
12 * frontswap pages are unused(moved to page cache).
13 * Used in in shmem_unuse and try_to_unuse.
14 */
15#define FRONTSWAP_PAGES_UNUSED 2
16
17struct frontswap_ops {
18 void (*init)(unsigned); /* this swap type was just swapon'ed */
19 int (*store)(unsigned, pgoff_t, struct page *); /* store a page */
20 int (*load)(unsigned, pgoff_t, struct page *); /* load a page */
21 void (*invalidate_page)(unsigned, pgoff_t); /* page no longer needed */
22 void (*invalidate_area)(unsigned); /* swap type just swapoff'ed */
23 struct frontswap_ops *next; /* private pointer to next ops */
24};
25
26extern void frontswap_register_ops(struct frontswap_ops *ops);
27extern void frontswap_shrink(unsigned long);
28extern unsigned long frontswap_curr_pages(void);
29extern void frontswap_writethrough(bool);
30#define FRONTSWAP_HAS_EXCLUSIVE_GETS
31extern void frontswap_tmem_exclusive_gets(bool);
32
33extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
34extern void __frontswap_init(unsigned type, unsigned long *map);
35extern int __frontswap_store(struct page *page);
36extern int __frontswap_load(struct page *page);
37extern void __frontswap_invalidate_page(unsigned, pgoff_t);
38extern void __frontswap_invalidate_area(unsigned);
39
40#ifdef CONFIG_FRONTSWAP
41extern struct static_key_false frontswap_enabled_key;
42
43static inline bool frontswap_enabled(void)
44{
45 return static_branch_unlikely(&frontswap_enabled_key);
46}
47
48static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
49{
50 return __frontswap_test(sis, offset);
51}
52
53static inline void frontswap_map_set(struct swap_info_struct *p,
54 unsigned long *map)
55{
56 p->frontswap_map = map;
57}
58
59static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
60{
61 return p->frontswap_map;
62}
63#else
64/* all inline routines become no-ops and all externs are ignored */
65
66static inline bool frontswap_enabled(void)
67{
68 return false;
69}
70
71static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
72{
73 return false;
74}
75
76static inline void frontswap_map_set(struct swap_info_struct *p,
77 unsigned long *map)
78{
79}
80
81static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
82{
83 return NULL;
84}
85#endif
86
87static inline int frontswap_store(struct page *page)
88{
89 if (frontswap_enabled())
90 return __frontswap_store(page);
91
92 return -1;
93}
94
95static inline int frontswap_load(struct page *page)
96{
97 if (frontswap_enabled())
98 return __frontswap_load(page);
99
100 return -1;
101}
102
103static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
104{
105 if (frontswap_enabled())
106 __frontswap_invalidate_page(type, offset);
107}
108
109static inline void frontswap_invalidate_area(unsigned type)
110{
111 if (frontswap_enabled())
112 __frontswap_invalidate_area(type);
113}
114
115static inline void frontswap_init(unsigned type, unsigned long *map)
116{
117#ifdef CONFIG_FRONTSWAP
118 __frontswap_init(type, map);
119#endif
120}
121
122#endif /* _LINUX_FRONTSWAP_H */