mm/swap.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _MM_SWAP_H
   3 #define _MM_SWAP_H
   4
   5 struct mempolicy;
   6
   7 #ifdef CONFIG_SWAP
   8 #include <linux/swapops.h> /* for swp_offset */
   9 #include <linux/blk_types.h> /* for bio_end_io_t */
  10
  11 /* linux/mm/page_io.c */
  12 int sio_pool_init(void);
  13 struct swap_iocb;
  14 void swap_read_folio(struct folio *folio, struct swap_iocb **plug);
  15 void __swap_read_unplug(struct swap_iocb *plug);
  16 static inline void swap_read_unplug(struct swap_iocb *plug)
  17 {
  18         if (unlikely(plug))
  19                 __swap_read_unplug(plug);
  20 }
  21 void swap_write_unplug(struct swap_iocb *sio);
  22 int swap_writepage(struct page *page, struct writeback_control *wbc);
  23 void __swap_writepage(struct folio *folio, struct writeback_control *wbc);
  24
  25 /* linux/mm/swap_state.c */
  26 /* One swap address space for each 64M swap space */
  27 #define SWAP_ADDRESS_SPACE_SHIFT        14
  28 #define SWAP_ADDRESS_SPACE_PAGES        (1 << SWAP_ADDRESS_SPACE_SHIFT)
  29 #define SWAP_ADDRESS_SPACE_MASK         (SWAP_ADDRESS_SPACE_PAGES - 1)
  30 extern struct address_space *swapper_spaces[];
  31 #define swap_address_space(entry)                           \
  32         (&swapper_spaces[swp_type(entry)][swp_offset(entry) \
  33                 >> SWAP_ADDRESS_SPACE_SHIFT])
  34
  35 /*
  36  * Return the swap device position of the swap entry.
  37  */
  38 static inline loff_t swap_dev_pos(swp_entry_t entry)
  39 {
  40         return ((loff_t)swp_offset(entry)) << PAGE_SHIFT;
  41 }
  42
  43 /*
  44  * Return the swap cache index of the swap entry.
  45  */
  46 static inline pgoff_t swap_cache_index(swp_entry_t entry)
  47 {
  48         BUILD_BUG_ON((SWP_OFFSET_MASK | SWAP_ADDRESS_SPACE_MASK) != SWP_OFFSET_MASK);
  49         return swp_offset(entry) & SWAP_ADDRESS_SPACE_MASK;
  50 }
  51
  52 void show_swap_cache_info(void);
  53 bool add_to_swap(struct folio *folio);
  54 void *get_shadow_from_swap_cache(swp_entry_t entry);
  55 int add_to_swap_cache(struct folio *folio, swp_entry_t entry,
  56                       gfp_t gfp, void **shadowp);
  57 void __delete_from_swap_cache(struct folio *folio,
  58                               swp_entry_t entry, void *shadow);
  59 void delete_from_swap_cache(struct folio *folio);
  60 void clear_shadow_from_swap_cache(int type, unsigned long begin,
  61                                   unsigned long end);
  62 void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr);
  63 struct folio *swap_cache_get_folio(swp_entry_t entry,
  64                 struct vm_area_struct *vma, unsigned long addr);
  65 struct folio *filemap_get_incore_folio(struct address_space *mapping,
  66                 pgoff_t index);
  67
  68 struct folio *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
  69                 struct vm_area_struct *vma, unsigned long addr,
  70                 struct swap_iocb **plug);
  71 struct folio *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_flags,
  72                 struct mempolicy *mpol, pgoff_t ilx, bool *new_page_allocated,
  73                 bool skip_if_exists);
  74 struct folio *swap_cluster_readahead(swp_entry_t entry, gfp_t flag,
  75                 struct mempolicy *mpol, pgoff_t ilx);
  76 struct folio *swapin_readahead(swp_entry_t entry, gfp_t flag,
  77                 struct vm_fault *vmf);
  78
  79 static inline unsigned int folio_swap_flags(struct folio *folio)
  80 {
  81         return swp_swap_info(folio->swap)->flags;
  82 }
  83
  84 /*
  85  * Return the count of contiguous swap entries that share the same
  86  * zeromap status as the starting entry. If is_zeromap is not NULL,
  87  * it will return the zeromap status of the starting entry.
  88  */
  89 static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr,
  90                 bool *is_zeromap)
  91 {
  92         struct swap_info_struct *sis = swp_swap_info(entry);
  93         unsigned long start = swp_offset(entry);
  94         unsigned long end = start + max_nr;
  95         bool first_bit;
  96
  97         first_bit = test_bit(start, sis->zeromap);
  98         if (is_zeromap)
  99                 *is_zeromap = first_bit;
 100
 101         if (max_nr <= 1)
 102                 return max_nr;
 103         if (first_bit)
 104                 return find_next_zero_bit(sis->zeromap, end, start) - start;
 105         else
 106                 return find_next_bit(sis->zeromap, end, start) - start;
 107 }
 108
 109 #else /* CONFIG_SWAP */
 110 struct swap_iocb;
 111 static inline void swap_read_folio(struct folio *folio, struct swap_iocb **plug)
 112 {
 113 }
 114 static inline void swap_write_unplug(struct swap_iocb *sio)
 115 {
 116 }
 117
 118 static inline struct address_space *swap_address_space(swp_entry_t entry)
 119 {
 120         return NULL;
 121 }
 122
 123 static inline pgoff_t swap_cache_index(swp_entry_t entry)
 124 {
 125         return 0;
 126 }
 127
 128 static inline void show_swap_cache_info(void)
 129 {
 130 }
 131
 132 static inline struct folio *swap_cluster_readahead(swp_entry_t entry,
 133                         gfp_t gfp_mask, struct mempolicy *mpol, pgoff_t ilx)
 134 {
 135         return NULL;
 136 }
 137
 138 static inline struct folio *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 139                         struct vm_fault *vmf)
 140 {
 141         return NULL;
 142 }
 143
 144 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 145 {
 146         return 0;
 147 }
 148
 149 static inline void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr)
 150 {
 151 }
 152
 153 static inline struct folio *swap_cache_get_folio(swp_entry_t entry,
 154                 struct vm_area_struct *vma, unsigned long addr)
 155 {
 156         return NULL;
 157 }
 158
 159 static inline
 160 struct folio *filemap_get_incore_folio(struct address_space *mapping,
 161                 pgoff_t index)
 162 {
 163         return filemap_get_folio(mapping, index);
 164 }
 165
 166 static inline bool add_to_swap(struct folio *folio)
 167 {
 168         return false;
 169 }
 170
 171 static inline void *get_shadow_from_swap_cache(swp_entry_t entry)
 172 {
 173         return NULL;
 174 }
 175
 176 static inline int add_to_swap_cache(struct folio *folio, swp_entry_t entry,
 177                                         gfp_t gfp_mask, void **shadowp)
 178 {
 179         return -1;
 180 }
 181
 182 static inline void __delete_from_swap_cache(struct folio *folio,
 183                                         swp_entry_t entry, void *shadow)
 184 {
 185 }
 186
 187 static inline void delete_from_swap_cache(struct folio *folio)
 188 {
 189 }
 190
 191 static inline void clear_shadow_from_swap_cache(int type, unsigned long begin,
 192                                 unsigned long end)
 193 {
 194 }
 195
 196 static inline unsigned int folio_swap_flags(struct folio *folio)
 197 {
 198         return 0;
 199 }
 200
 201 static inline int swap_zeromap_batch(swp_entry_t entry, int max_nr,
 202                 bool *has_zeromap)
 203 {
 204         return 0;
 205 }
 206
 207 #endif /* CONFIG_SWAP */
 208
 209 #endif /* _MM_SWAP_H */