Line data    Source code

       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 shmem_unuse and try_to_unuse.
      14             :  */
      15             : #define FRONTSWAP_PAGES_UNUSED  2
      16             : 
      17             : struct 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             : 
      26             : extern void frontswap_register_ops(struct frontswap_ops *ops);
      27             : extern void frontswap_shrink(unsigned long);
      28             : extern unsigned long frontswap_curr_pages(void);
      29             : extern void frontswap_writethrough(bool);
      30             : #define FRONTSWAP_HAS_EXCLUSIVE_GETS
      31             : extern void frontswap_tmem_exclusive_gets(bool);
      32             : 
      33             : extern bool __frontswap_test(struct swap_info_struct *, pgoff_t);
      34             : extern void __frontswap_init(unsigned type, unsigned long *map);
      35             : extern int __frontswap_store(struct page *page);
      36             : extern int __frontswap_load(struct page *page);
      37             : extern void __frontswap_invalidate_page(unsigned, pgoff_t);
      38             : extern void __frontswap_invalidate_area(unsigned);
      39             : 
      40             : #ifdef CONFIG_FRONTSWAP
      41             : extern struct static_key_false frontswap_enabled_key;
      42             : 
      43             : static inline bool frontswap_enabled(void)
      44             : {
      45             :         return static_branch_unlikely(&frontswap_enabled_key);
      46             : }
      47             : 
      48             : static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
      49             : {
      50             :         return __frontswap_test(sis, offset);
      51             : }
      52             : 
      53             : static inline void frontswap_map_set(struct swap_info_struct *p,
      54             :                                      unsigned long *map)
      55             : {
      56             :         p->frontswap_map = map;
      57             : }
      58             : 
      59             : static 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             : 
      66             : static inline bool frontswap_enabled(void)
      67             : {
      68             :         return false;
      69             : }
      70             : 
      71           0 : static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
      72             : {
      73           0 :         return false;
      74             : }
      75             : 
      76             : static inline void frontswap_map_set(struct swap_info_struct *p,
      77             :                                      unsigned long *map)
      78             : {
      79             : }
      80             : 
      81             : static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
      82             : {
      83             :         return NULL;
      84             : }
      85             : #endif
      86             : 
      87             : static inline int frontswap_store(struct page *page)
      88             : {
      89             :         if (frontswap_enabled())
      90             :                 return __frontswap_store(page);
      91             : 
      92             :         return -1;
      93             : }
      94             : 
      95             : static inline int frontswap_load(struct page *page)
      96             : {
      97             :         if (frontswap_enabled())
      98             :                 return __frontswap_load(page);
      99             : 
     100             :         return -1;
     101             : }
     102             : 
     103             : static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
     104             : {
     105             :         if (frontswap_enabled())
     106             :                 __frontswap_invalidate_page(type, offset);
     107             : }
     108             : 
     109             : static inline void frontswap_invalidate_area(unsigned type)
     110             : {
     111             :         if (frontswap_enabled())
     112             :                 __frontswap_invalidate_area(type);
     113             : }
     114             : 
     115             : static 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 */