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 struct notifier_block;
  14
  15 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  16 #define SWAP_FLAG_PRIO_MASK     0x7fff
  17 #define SWAP_FLAG_PRIO_SHIFT    0
  18
  19 static inline int current_is_kswapd(void)
  20 {
  21         return current->flags & PF_KSWAPD;
  22 }
  23
  24 /*
  25  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  26  * be swapped to.  The swap type and the offset into that swap type are
  27  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  28  * for the type means that the maximum number of swapcache pages is 27 bits
  29  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  30  * the type/offset into the pte as 5/27 as well.
  31  */
  32 #define MAX_SWAPFILES_SHIFT     5
  33 #ifndef CONFIG_MIGRATION
  34 #define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  35 #else
  36 /* Use last two entries for page migration swap entries */
  37 #define MAX_SWAPFILES           ((1 << MAX_SWAPFILES_SHIFT)-2)
  38 #define SWP_MIGRATION_READ      MAX_SWAPFILES
  39 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + 1)
  40 #endif
  41
  42 /*
  43  * Magic header for a swap area. The first part of the union is
  44  * what the swap magic looks like for the old (limited to 128MB)
  45  * swap area format, the second part of the union adds - in the
  46  * old reserved area - some extra information. Note that the first
  47  * kilobyte is reserved for boot loader or disk label stuff...
  48  *
  49  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  50  * areas somewhat tricky on machines that support multiple page sizes.
  51  * For 2.5 we'll probably want to move the magic to just beyond the
  52  * bootbits...
  53  */
  54 union swap_header {
  55         struct {
  56                 char reserved[PAGE_SIZE - 10];
  57                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  58         } magic;
  59         struct {
  60                 char            bootbits[1024]; /* Space for disklabel etc. */
  61                 __u32           version;
  62                 __u32           last_page;
  63                 __u32           nr_badpages;
  64                 unsigned char   sws_uuid[16];
  65                 unsigned char   sws_volume[16];
  66                 __u32           padding[117];
  67                 __u32           badpages[1];
  68         } info;
  69 };
  70
  71  /* A swap entry has to fit into a "unsigned long", as
  72   * the entry is hidden in the "index" field of the
  73   * swapper address space.
  74   */
  75 typedef struct {
  76         unsigned long val;
  77 } swp_entry_t;
  78
  79 /*
  80  * current->reclaim_state points to one of these when a task is running
  81  * memory reclaim
  82  */
  83 struct reclaim_state {
  84         unsigned long reclaimed_slab;
  85 };
  86
  87 #ifdef __KERNEL__
  88
  89 struct address_space;
  90 struct sysinfo;
  91 struct writeback_control;
  92 struct zone;
  93
  94 /*
  95  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
  96  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
  97  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
  98  * from setup, they're handled identically.
  99  *
 100  * We always assume that blocks are of size PAGE_SIZE.
 101  */
 102 struct swap_extent {
 103         struct list_head list;
 104         pgoff_t start_page;
 105         pgoff_t nr_pages;
 106         sector_t start_block;
 107 };
 108
 109 /*
 110  * Max bad pages in the new format..
 111  */
 112 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 113 #define MAX_SWAP_BADPAGES \
 114         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 115
 116 enum {
 117         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 118         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 119         SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 120                                         /* add others here before... */
 121         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 122 };
 123
 124 #define SWAP_CLUSTER_MAX 32
 125
 126 #define SWAP_MAP_MAX    0x7fff
 127 #define SWAP_MAP_BAD    0x8000
 128
 129 /*
 130  * The in-memory structure used to track swap areas.
 131  */
 132 struct swap_info_struct {
 133         unsigned int flags;
 134         int prio;                       /* swap priority */
 135         struct file *swap_file;
 136         struct block_device *bdev;
 137         struct list_head extent_list;
 138         struct swap_extent *curr_swap_extent;
 139         unsigned old_block_size;
 140         unsigned short * swap_map;
 141         unsigned int lowest_bit;
 142         unsigned int highest_bit;
 143         unsigned int cluster_next;
 144         unsigned int cluster_nr;
 145         unsigned int pages;
 146         unsigned int max;
 147         unsigned int inuse_pages;
 148         int next;                       /* next entry on swap list */
 149 };
 150
 151 struct swap_list_t {
 152         int head;       /* head of priority-ordered swapfile list */
 153         int next;       /* swapfile to be used next */
 154 };
 155
 156 /* Swap 50% full? Release swapcache more aggressively.. */
 157 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 158
 159 /* linux/mm/oom_kill.c */
 160 extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
 161 extern int register_oom_notifier(struct notifier_block *nb);
 162 extern int unregister_oom_notifier(struct notifier_block *nb);
 163
 164 /* linux/mm/memory.c */
 165 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 166
 167 /* linux/mm/page_alloc.c */
 168 extern unsigned long totalram_pages;
 169 extern unsigned long totalreserve_pages;
 170 extern long nr_swap_pages;
 171 extern unsigned int nr_free_pages(void);
 172 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
 173 extern unsigned int nr_free_buffer_pages(void);
 174 extern unsigned int nr_free_pagecache_pages(void);
 175
 176 /* linux/mm/swap.c */
 177 extern void FASTCALL(lru_cache_add(struct page *));
 178 extern void FASTCALL(lru_cache_add_active(struct page *));
 179 extern void FASTCALL(activate_page(struct page *));
 180 extern void FASTCALL(mark_page_accessed(struct page *));
 181 extern void lru_add_drain(void);
 182 extern int lru_add_drain_all(void);
 183 extern int rotate_reclaimable_page(struct page *page);
 184 extern void swap_setup(void);
 185
 186 /* linux/mm/vmscan.c */
 187 extern unsigned long try_to_free_pages(struct zone **, gfp_t);
 188 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 189 extern int vm_swappiness;
 190 extern int remove_mapping(struct address_space *mapping, struct page *page);
 191 extern long vm_total_pages;
 192
 193 #ifdef CONFIG_NUMA
 194 extern int zone_reclaim_mode;
 195 extern int sysctl_min_unmapped_ratio;
 196 extern int sysctl_min_slab_ratio;
 197 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 198 #else
 199 #define zone_reclaim_mode 0
 200 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 201 {
 202         return 0;
 203 }
 204 #endif
 205
 206 extern int kswapd_run(int nid);
 207
 208 #ifdef CONFIG_MMU
 209 /* linux/mm/shmem.c */
 210 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 211 #endif /* CONFIG_MMU */
 212
 213 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 214
 215 #ifdef CONFIG_SWAP
 216 /* linux/mm/page_io.c */
 217 extern int swap_readpage(struct file *, struct page *);
 218 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 219 extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
 220
 221 /* linux/mm/swap_state.c */
 222 extern struct address_space swapper_space;
 223 #define total_swapcache_pages  swapper_space.nrpages
 224 extern void show_swap_cache_info(void);
 225 extern int add_to_swap(struct page *, gfp_t);
 226 extern void __delete_from_swap_cache(struct page *);
 227 extern void delete_from_swap_cache(struct page *);
 228 extern int move_to_swap_cache(struct page *, swp_entry_t);
 229 extern int move_from_swap_cache(struct page *, unsigned long,
 230                 struct address_space *);
 231 extern void free_page_and_swap_cache(struct page *);
 232 extern void free_pages_and_swap_cache(struct page **, int);
 233 extern struct page * lookup_swap_cache(swp_entry_t);
 234 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 235                                            unsigned long addr);
 236 /* linux/mm/swapfile.c */
 237 extern long total_swap_pages;
 238 extern unsigned int nr_swapfiles;
 239 extern void si_swapinfo(struct sysinfo *);
 240 extern swp_entry_t get_swap_page(void);
 241 extern swp_entry_t get_swap_page_of_type(int);
 242 extern int swap_duplicate(swp_entry_t);
 243 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 244 extern void swap_free(swp_entry_t);
 245 extern void free_swap_and_cache(swp_entry_t);
 246 extern int swap_type_of(dev_t);
 247 extern unsigned int count_swap_pages(int, int);
 248 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 249 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 250 extern int can_share_swap_page(struct page *);
 251 extern int remove_exclusive_swap_page(struct page *);
 252 struct backing_dev_info;
 253
 254 extern spinlock_t swap_lock;
 255
 256 /* linux/mm/thrash.c */
 257 extern struct mm_struct * swap_token_mm;
 258 extern unsigned long swap_token_default_timeout;
 259 extern void grab_swap_token(void);
 260 extern void __put_swap_token(struct mm_struct *);
 261
 262 static inline int has_swap_token(struct mm_struct *mm)
 263 {
 264         return (mm == swap_token_mm);
 265 }
 266
 267 static inline void put_swap_token(struct mm_struct *mm)
 268 {
 269         if (has_swap_token(mm))
 270                 __put_swap_token(mm);
 271 }
 272
 273 static inline void disable_swap_token(void)
 274 {
 275         put_swap_token(swap_token_mm);
 276 }
 277
 278 #else /* CONFIG_SWAP */
 279
 280 #define total_swap_pages                        0
 281 #define total_swapcache_pages                   0UL
 282
 283 #define si_swapinfo(val) \
 284         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 285 /* only sparc can not include linux/pagemap.h in this file
 286  * so leave page_cache_release and release_pages undeclared... */
 287 #define free_page_and_swap_cache(page) \
 288         page_cache_release(page)
 289 #define free_pages_and_swap_cache(pages, nr) \
 290         release_pages((pages), (nr), 0);
 291
 292 static inline void show_swap_cache_info(void)
 293 {
 294 }
 295
 296 static inline void free_swap_and_cache(swp_entry_t swp)
 297 {
 298 }
 299
 300 static inline int swap_duplicate(swp_entry_t swp)
 301 {
 302         return 0;
 303 }
 304
 305 static inline void swap_free(swp_entry_t swp)
 306 {
 307 }
 308
 309 static inline struct page *read_swap_cache_async(swp_entry_t swp,
 310                         struct vm_area_struct *vma, unsigned long addr)
 311 {
 312         return NULL;
 313 }
 314
 315 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 316 {
 317         return NULL;
 318 }
 319
 320 static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
 321 {
 322         return 0;
 323 }
 324
 325 #define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 326
 327 static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
 328 {
 329         return 1;
 330 }
 331
 332 static inline int move_from_swap_cache(struct page *page, unsigned long index,
 333                                         struct address_space *mapping)
 334 {
 335         return 1;
 336 }
 337
 338 static inline void __delete_from_swap_cache(struct page *page)
 339 {
 340 }
 341
 342 static inline void delete_from_swap_cache(struct page *page)
 343 {
 344 }
 345
 346 #define swap_token_default_timeout              0
 347
 348 static inline int remove_exclusive_swap_page(struct page *p)
 349 {
 350         return 0;
 351 }
 352
 353 static inline swp_entry_t get_swap_page(void)
 354 {
 355         swp_entry_t entry;
 356         entry.val = 0;
 357         return entry;
 358 }
 359
 360 /* linux/mm/thrash.c */
 361 #define put_swap_token(x) do { } while(0)
 362 #define grab_swap_token()  do { } while(0)
 363 #define has_swap_token(x) 0
 364 #define disable_swap_token() do { } while(0)
 365
 366 #endif /* CONFIG_SWAP */
 367 #endif /* __KERNEL__*/
 368 #endif /* _LINUX_SWAP_H */