1#ifndef _LINUX_FRONTSWAP_H
  2#define _LINUX_FRONTSWAP_H
  3
  4#include <linux/swap.h>
  5#include <linux/mm.h>
  6#include <linux/bitops.h>
  7
  8struct frontswap_ops {
  9	void (*init)(unsigned);
 10	int (*store)(unsigned, pgoff_t, struct page *);
 11	int (*load)(unsigned, pgoff_t, struct page *);
 12	void (*invalidate_page)(unsigned, pgoff_t);
 13	void (*invalidate_area)(unsigned);
 14};
 15
 16extern bool frontswap_enabled;
 17extern struct frontswap_ops
 18	frontswap_register_ops(struct frontswap_ops *ops);
 19extern void frontswap_shrink(unsigned long);
 20extern unsigned long frontswap_curr_pages(void);
 21extern void frontswap_writethrough(bool);
 22
 23extern void __frontswap_init(unsigned type);
 24extern int __frontswap_store(struct page *page);
 25extern int __frontswap_load(struct page *page);
 26extern void __frontswap_invalidate_page(unsigned, pgoff_t);
 27extern void __frontswap_invalidate_area(unsigned);
 28
 29#ifdef CONFIG_FRONTSWAP
 30
 31static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
 32{
 33	bool ret = false;
 34
 35	if (frontswap_enabled && sis->frontswap_map)
 36		ret = test_bit(offset, sis->frontswap_map);
 37	return ret;
 38}
 39
 40static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
 41{
 42	if (frontswap_enabled && sis->frontswap_map)
 43		set_bit(offset, sis->frontswap_map);
 44}
 45
 46static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
 47{
 48	if (frontswap_enabled && sis->frontswap_map)
 49		clear_bit(offset, sis->frontswap_map);
 50}
 51
 52static inline void frontswap_map_set(struct swap_info_struct *p,
 53				     unsigned long *map)
 54{
 55	p->frontswap_map = map;
 56}
 57
 58static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
 59{
 60	return p->frontswap_map;
 61}
 62#else
 63/* all inline routines become no-ops and all externs are ignored */
 64
 65#define frontswap_enabled (0)
 66
 67static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
 68{
 69	return false;
 70}
 71
 72static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
 73{
 74}
 75
 76static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
 77{
 78}
 79
 80static inline void frontswap_map_set(struct swap_info_struct *p,
 81				     unsigned long *map)
 82{
 83}
 84
 85static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
 86{
 87	return NULL;
 88}
 89#endif
 90
 91static inline int frontswap_store(struct page *page)
 92{
 93	int ret = -1;
 94
 95	if (frontswap_enabled)
 96		ret = __frontswap_store(page);
 97	return ret;
 98}
 99
100static inline int frontswap_load(struct page *page)
101{
102	int ret = -1;
103
104	if (frontswap_enabled)
105		ret = __frontswap_load(page);
106	return ret;
107}
108
109static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
110{
111	if (frontswap_enabled)
112		__frontswap_invalidate_page(type, offset);
113}
114
115static inline void frontswap_invalidate_area(unsigned type)
116{
117	if (frontswap_enabled)
118		__frontswap_invalidate_area(type);
119}
120
121static inline void frontswap_init(unsigned type)
122{
123	if (frontswap_enabled)
124		__frontswap_init(type);
125}
126
127#endif /* _LINUX_FRONTSWAP_H */