include/linux/swap.h

   1 #ifndef _LINUX_SWAP_H
   2 #define _LINUX_SWAP_H
   3
   4 #include <linux/spinlock.h>
   5 #include <linux/linkage.h>
   6 #include <linux/mmzone.h>
   7 #include <linux/list.h>
   8 #include <linux/sched.h>
   9
  10 #include <asm/atomic.h>
  11 #include <asm/page.h>
  12
  13 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  14 #define SWAP_FLAG_PRIO_MASK     0x7fff
  15 #define SWAP_FLAG_PRIO_SHIFT    0
  16
  17 static inline int current_is_kswapd(void)
  18 {
  19         return current->flags & PF_KSWAPD;
  20 }
  21
  22 /*
  23  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  24  * be swapped to.  The swap type and the offset into that swap type are
  25  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  26  * for the type means that the maximum number of swapcache pages is 27 bits
  27  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  28  * the type/offset into the pte as 5/27 as well.
  29  */
  30 #define MAX_SWAPFILES_SHIFT     5
  31 #ifndef CONFIG_MIGRATION
  32 #define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  33 #else
  34 /* Use last two entries for page migration swap entries */
  35 #define MAX_SWAPFILES           ((1 << MAX_SWAPFILES_SHIFT)-2)
  36 #define SWP_MIGRATION_READ      MAX_SWAPFILES
  37 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + 1)
  38 #endif
  39
  40 /*
  41  * Magic header for a swap area. The first part of the union is
  42  * what the swap magic looks like for the old (limited to 128MB)
  43  * swap area format, the second part of the union adds - in the
  44  * old reserved area - some extra information. Note that the first
  45  * kilobyte is reserved for boot loader or disk label stuff...
  46  *
  47  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  48  * areas somewhat tricky on machines that support multiple page sizes.
  49  * For 2.5 we'll probably want to move the magic to just beyond the
  50  * bootbits...
  51  */
  52 union swap_header {
  53         struct {
  54                 char reserved[PAGE_SIZE - 10];
  55                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  56         } magic;
  57         struct {
  58                 char            bootbits[1024]; /* Space for disklabel etc. */
  59                 __u32           version;
  60                 __u32           last_page;
  61                 __u32           nr_badpages;
  62                 unsigned char   sws_uuid[16];
  63                 unsigned char   sws_volume[16];
  64                 __u32           padding[117];
  65                 __u32           badpages[1];
  66         } info;
  67 };
  68
  69  /* A swap entry has to fit into a "unsigned long", as
  70   * the entry is hidden in the "index" field of the
  71   * swapper address space.
  72   */
  73 typedef struct {
  74         unsigned long val;
  75 } swp_entry_t;
  76
  77 /*
  78  * current->reclaim_state points to one of these when a task is running
  79  * memory reclaim
  80  */
  81 struct reclaim_state {
  82         unsigned long reclaimed_slab;
  83 };
  84
  85 #ifdef __KERNEL__
  86
  87 struct address_space;
  88 struct sysinfo;
  89 struct writeback_control;
  90 struct zone;
  91
  92 /*
  93  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
  94  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
  95  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
  96  * from setup, they're handled identically.
  97  *
  98  * We always assume that blocks are of size PAGE_SIZE.
  99  */
 100 struct swap_extent {
 101         struct list_head list;
 102         pgoff_t start_page;
 103         pgoff_t nr_pages;
 104         sector_t start_block;
 105 };
 106
 107 /*
 108  * Max bad pages in the new format..
 109  */
 110 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 111 #define MAX_SWAP_BADPAGES \
 112         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 113
 114 enum {
 115         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 116         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 117         SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 118                                         /* add others here before... */
 119         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 120 };
 121
 122 #define SWAP_CLUSTER_MAX 32
 123
 124 #define SWAP_MAP_MAX    0x7fff
 125 #define SWAP_MAP_BAD    0x8000
 126
 127 /*
 128  * The in-memory structure used to track swap areas.
 129  */
 130 struct swap_info_struct {
 131         unsigned int flags;
 132         int prio;                       /* swap priority */
 133         struct file *swap_file;
 134         struct block_device *bdev;
 135         struct list_head extent_list;
 136         struct swap_extent *curr_swap_extent;
 137         unsigned old_block_size;
 138         unsigned short * swap_map;
 139         unsigned int lowest_bit;
 140         unsigned int highest_bit;
 141         unsigned int cluster_next;
 142         unsigned int cluster_nr;
 143         unsigned int pages;
 144         unsigned int max;
 145         unsigned int inuse_pages;
 146         int next;                       /* next entry on swap list */
 147 };
 148
 149 struct swap_list_t {
 150         int head;       /* head of priority-ordered swapfile list */
 151         int next;       /* swapfile to be used next */
 152 };
 153
 154 /* Swap 50% full? Release swapcache more aggressively.. */
 155 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 156
 157 /* linux/mm/oom_kill.c */
 158 extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
 159
 160 /* linux/mm/memory.c */
 161 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 162
 163 /* linux/mm/page_alloc.c */
 164 extern unsigned long totalram_pages;
 165 extern unsigned long totalhigh_pages;
 166 extern unsigned long totalreserve_pages;
 167 extern long nr_swap_pages;
 168 extern unsigned int nr_free_pages(void);
 169 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
 170 extern unsigned int nr_free_buffer_pages(void);
 171 extern unsigned int nr_free_pagecache_pages(void);
 172
 173 /* linux/mm/swap.c */
 174 extern void FASTCALL(lru_cache_add(struct page *));
 175 extern void FASTCALL(lru_cache_add_active(struct page *));
 176 extern void FASTCALL(activate_page(struct page *));
 177 extern void FASTCALL(mark_page_accessed(struct page *));
 178 extern void lru_add_drain(void);
 179 extern int lru_add_drain_all(void);
 180 extern int rotate_reclaimable_page(struct page *page);
 181 extern void swap_setup(void);
 182
 183 /* linux/mm/vmscan.c */
 184 extern unsigned long try_to_free_pages(struct zone **, gfp_t);
 185 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 186 extern int vm_swappiness;
 187 extern int remove_mapping(struct address_space *mapping, struct page *page);
 188 extern long vm_total_pages;
 189
 190 #ifdef CONFIG_NUMA
 191 extern int zone_reclaim_mode;
 192 extern int sysctl_min_unmapped_ratio;
 193 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 194 #else
 195 #define zone_reclaim_mode 0
 196 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 197 {
 198         return 0;
 199 }
 200 #endif
 201
 202 extern int kswapd_run(int nid);
 203
 204 #ifdef CONFIG_MMU
 205 /* linux/mm/shmem.c */
 206 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 207 #endif /* CONFIG_MMU */
 208
 209 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 210
 211 #ifdef CONFIG_SWAP
 212 /* linux/mm/page_io.c */
 213 extern int swap_readpage(struct file *, struct page *);
 214 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 215 extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
 216
 217 /* linux/mm/swap_state.c */
 218 extern struct address_space swapper_space;
 219 #define total_swapcache_pages  swapper_space.nrpages
 220 extern void show_swap_cache_info(void);
 221 extern int add_to_swap(struct page *, gfp_t);
 222 extern void __delete_from_swap_cache(struct page *);
 223 extern void delete_from_swap_cache(struct page *);
 224 extern int move_to_swap_cache(struct page *, swp_entry_t);
 225 extern int move_from_swap_cache(struct page *, unsigned long,
 226                 struct address_space *);
 227 extern void free_page_and_swap_cache(struct page *);
 228 extern void free_pages_and_swap_cache(struct page **, int);
 229 extern struct page * lookup_swap_cache(swp_entry_t);
 230 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 231                                            unsigned long addr);
 232 /* linux/mm/swapfile.c */
 233 extern long total_swap_pages;
 234 extern unsigned int nr_swapfiles;
 235 extern void si_swapinfo(struct sysinfo *);
 236 extern swp_entry_t get_swap_page(void);
 237 extern swp_entry_t get_swap_page_of_type(int);
 238 extern int swap_duplicate(swp_entry_t);
 239 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 240 extern void swap_free(swp_entry_t);
 241 extern void free_swap_and_cache(swp_entry_t);
 242 extern int swap_type_of(dev_t);
 243 extern unsigned int count_swap_pages(int, int);
 244 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 245 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 246 extern int can_share_swap_page(struct page *);
 247 extern int remove_exclusive_swap_page(struct page *);
 248 struct backing_dev_info;
 249
 250 extern spinlock_t swap_lock;
 251
 252 /* linux/mm/thrash.c */
 253 extern struct mm_struct * swap_token_mm;
 254 extern unsigned long swap_token_default_timeout;
 255 extern void grab_swap_token(void);
 256 extern void __put_swap_token(struct mm_struct *);
 257
 258 static inline int has_swap_token(struct mm_struct *mm)
 259 {
 260         return (mm == swap_token_mm);
 261 }
 262
 263 static inline void put_swap_token(struct mm_struct *mm)
 264 {
 265         if (has_swap_token(mm))
 266                 __put_swap_token(mm);
 267 }
 268
 269 static inline void disable_swap_token(void)
 270 {
 271         put_swap_token(swap_token_mm);
 272 }
 273
 274 #else /* CONFIG_SWAP */
 275
 276 #define total_swap_pages                        0
 277 #define total_swapcache_pages                   0UL
 278
 279 #define si_swapinfo(val) \
 280         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 281 /* only sparc can not include linux/pagemap.h in this file
 282  * so leave page_cache_release and release_pages undeclared... */
 283 #define free_page_and_swap_cache(page) \
 284         page_cache_release(page)
 285 #define free_pages_and_swap_cache(pages, nr) \
 286         release_pages((pages), (nr), 0);
 287
 288 static inline void show_swap_cache_info(void)
 289 {
 290 }
 291
 292 static inline void free_swap_and_cache(swp_entry_t swp)
 293 {
 294 }
 295
 296 static inline int swap_duplicate(swp_entry_t swp)
 297 {
 298         return 0;
 299 }
 300
 301 static inline void swap_free(swp_entry_t swp)
 302 {
 303 }
 304
 305 static inline struct page *read_swap_cache_async(swp_entry_t swp,
 306                         struct vm_area_struct *vma, unsigned long addr)
 307 {
 308         return NULL;
 309 }
 310
 311 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 312 {
 313         return NULL;
 314 }
 315
 316 static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
 317 {
 318         return 0;
 319 }
 320
 321 #define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 322
 323 static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
 324 {
 325         return 1;
 326 }
 327
 328 static inline int move_from_swap_cache(struct page *page, unsigned long index,
 329                                         struct address_space *mapping)
 330 {
 331         return 1;
 332 }
 333
 334 static inline void __delete_from_swap_cache(struct page *page)
 335 {
 336 }
 337
 338 static inline void delete_from_swap_cache(struct page *page)
 339 {
 340 }
 341
 342 #define swap_token_default_timeout              0
 343
 344 static inline int remove_exclusive_swap_page(struct page *p)
 345 {
 346         return 0;
 347 }
 348
 349 static inline swp_entry_t get_swap_page(void)
 350 {
 351         swp_entry_t entry;
 352         entry.val = 0;
 353         return entry;
 354 }
 355
 356 /* linux/mm/thrash.c */
 357 #define put_swap_token(x) do { } while(0)
 358 #define grab_swap_token()  do { } while(0)
 359 #define has_swap_token(x) 0
 360 #define disable_swap_token() do { } while(0)
 361
 362 #endif /* CONFIG_SWAP */
 363 #endif /* __KERNEL__*/
 364 #endif /* _LINUX_SWAP_H */