LXR linux/include/linux/frontswap.h

   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 */
 123