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/memcontrol.h>
   9 #include <linux/sched.h>
  10 #include <linux/node.h>
  11
  12 #include <asm/atomic.h>
  13 #include <asm/page.h>
  14
  15 struct notifier_block;
  16
  17 struct bio;
  18
  19 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  20 #define SWAP_FLAG_PRIO_MASK     0x7fff
  21 #define SWAP_FLAG_PRIO_SHIFT    0
  22
  23 static inline int current_is_kswapd(void)
  24 {
  25         return current->flags & PF_KSWAPD;
  26 }
  27
  28 /*
  29  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  30  * be swapped to.  The swap type and the offset into that swap type are
  31  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  32  * for the type means that the maximum number of swapcache pages is 27 bits
  33  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  34  * the type/offset into the pte as 5/27 as well.
  35  */
  36 #define MAX_SWAPFILES_SHIFT     5
  37
  38 /*
  39  * Use some of the swap files numbers for other purposes. This
  40  * is a convenient way to hook into the VM to trigger special
  41  * actions on faults.
  42  */
  43
  44 /*
  45  * NUMA node memory migration support
  46  */
  47 #ifdef CONFIG_MIGRATION
  48 #define SWP_MIGRATION_NUM 2
  49 #define SWP_MIGRATION_READ      (MAX_SWAPFILES + SWP_HWPOISON_NUM)
  50 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
  51 #else
  52 #define SWP_MIGRATION_NUM 0
  53 #endif
  54
  55 /*
  56  * Handling of hardware poisoned pages with memory corruption.
  57  */
  58 #ifdef CONFIG_MEMORY_FAILURE
  59 #define SWP_HWPOISON_NUM 1
  60 #define SWP_HWPOISON            MAX_SWAPFILES
  61 #else
  62 #define SWP_HWPOISON_NUM 0
  63 #endif
  64
  65 #define MAX_SWAPFILES \
  66         ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
  67
  68 /*
  69  * Magic header for a swap area. The first part of the union is
  70  * what the swap magic looks like for the old (limited to 128MB)
  71  * swap area format, the second part of the union adds - in the
  72  * old reserved area - some extra information. Note that the first
  73  * kilobyte is reserved for boot loader or disk label stuff...
  74  *
  75  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  76  * areas somewhat tricky on machines that support multiple page sizes.
  77  * For 2.5 we'll probably want to move the magic to just beyond the
  78  * bootbits...
  79  */
  80 union swap_header {
  81         struct {
  82                 char reserved[PAGE_SIZE - 10];
  83                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  84         } magic;
  85         struct {
  86                 char            bootbits[1024]; /* Space for disklabel etc. */
  87                 __u32           version;
  88                 __u32           last_page;
  89                 __u32           nr_badpages;
  90                 unsigned char   sws_uuid[16];
  91                 unsigned char   sws_volume[16];
  92                 __u32           padding[117];
  93                 __u32           badpages[1];
  94         } info;
  95 };
  96
  97  /* A swap entry has to fit into a "unsigned long", as
  98   * the entry is hidden in the "index" field of the
  99   * swapper address space.
 100   */
 101 typedef struct {
 102         unsigned long val;
 103 } swp_entry_t;
 104
 105 /*
 106  * current->reclaim_state points to one of these when a task is running
 107  * memory reclaim
 108  */
 109 struct reclaim_state {
 110         unsigned long reclaimed_slab;
 111 };
 112
 113 #ifdef __KERNEL__
 114
 115 struct address_space;
 116 struct sysinfo;
 117 struct writeback_control;
 118 struct zone;
 119
 120 /*
 121  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 122  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 123  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 124  * from setup, they're handled identically.
 125  *
 126  * We always assume that blocks are of size PAGE_SIZE.
 127  */
 128 struct swap_extent {
 129         struct list_head list;
 130         pgoff_t start_page;
 131         pgoff_t nr_pages;
 132         sector_t start_block;
 133 };
 134
 135 /*
 136  * Max bad pages in the new format..
 137  */
 138 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 139 #define MAX_SWAP_BADPAGES \
 140         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 141
 142 enum {
 143         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 144         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 145         SWP_DISCARDABLE = (1 << 2),     /* blkdev supports discard */
 146         SWP_DISCARDING  = (1 << 3),     /* now discarding a free cluster */
 147         SWP_SOLIDSTATE  = (1 << 4),     /* blkdev seeks are cheap */
 148                                         /* add others here before... */
 149         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 150 };
 151
 152 #define SWAP_CLUSTER_MAX 32
 153
 154 #define SWAP_MAP_MAX    0x7ffe
 155 #define SWAP_MAP_BAD    0x7fff
 156 #define SWAP_HAS_CACHE  0x8000          /* There is a swap cache of entry. */
 157 #define SWAP_COUNT_MASK (~SWAP_HAS_CACHE)
 158 /*
 159  * The in-memory structure used to track swap areas.
 160  */
 161 struct swap_info_struct {
 162         unsigned long flags;
 163         int prio;                       /* swap priority */
 164         int next;                       /* next entry on swap list */
 165         struct file *swap_file;
 166         struct block_device *bdev;
 167         struct list_head extent_list;
 168         struct swap_extent *curr_swap_extent;
 169         unsigned short *swap_map;
 170         unsigned int lowest_bit;
 171         unsigned int highest_bit;
 172         unsigned int lowest_alloc;      /* while preparing discard cluster */
 173         unsigned int highest_alloc;     /* while preparing discard cluster */
 174         unsigned int cluster_next;
 175         unsigned int cluster_nr;
 176         unsigned int pages;
 177         unsigned int max;
 178         unsigned int inuse_pages;
 179         unsigned int old_block_size;
 180 };
 181
 182 struct swap_list_t {
 183         int head;       /* head of priority-ordered swapfile list */
 184         int next;       /* swapfile to be used next */
 185 };
 186
 187 /* Swap 50% full? Release swapcache more aggressively.. */
 188 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 189
 190 /* linux/mm/page_alloc.c */
 191 extern unsigned long totalram_pages;
 192 extern unsigned long totalreserve_pages;
 193 extern unsigned int nr_free_buffer_pages(void);
 194 extern unsigned int nr_free_pagecache_pages(void);
 195
 196 /* Definition of global_page_state not available yet */
 197 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 198
 199
 200 /* linux/mm/swap.c */
 201 extern void __lru_cache_add(struct page *, enum lru_list lru);
 202 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 203 extern void activate_page(struct page *);
 204 extern void mark_page_accessed(struct page *);
 205 extern void lru_add_drain(void);
 206 extern int lru_add_drain_all(void);
 207 extern void rotate_reclaimable_page(struct page *page);
 208 extern void swap_setup(void);
 209
 210 extern void add_page_to_unevictable_list(struct page *page);
 211
 212 /**
 213  * lru_cache_add: add a page to the page lists
 214  * @page: the page to add
 215  */
 216 static inline void lru_cache_add_anon(struct page *page)
 217 {
 218         __lru_cache_add(page, LRU_INACTIVE_ANON);
 219 }
 220
 221 static inline void lru_cache_add_active_anon(struct page *page)
 222 {
 223         __lru_cache_add(page, LRU_ACTIVE_ANON);
 224 }
 225
 226 static inline void lru_cache_add_file(struct page *page)
 227 {
 228         __lru_cache_add(page, LRU_INACTIVE_FILE);
 229 }
 230
 231 static inline void lru_cache_add_active_file(struct page *page)
 232 {
 233         __lru_cache_add(page, LRU_ACTIVE_FILE);
 234 }
 235
 236 /* linux/mm/vmscan.c */
 237 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 238                                         gfp_t gfp_mask, nodemask_t *mask);
 239 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 240                                                   gfp_t gfp_mask, bool noswap,
 241                                                   unsigned int swappiness);
 242 extern int __isolate_lru_page(struct page *page, int mode, int file);
 243 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 244 extern int vm_swappiness;
 245 extern int remove_mapping(struct address_space *mapping, struct page *page);
 246 extern long vm_total_pages;
 247
 248 #ifdef CONFIG_NUMA
 249 extern int zone_reclaim_mode;
 250 extern int sysctl_min_unmapped_ratio;
 251 extern int sysctl_min_slab_ratio;
 252 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 253 #else
 254 #define zone_reclaim_mode 0
 255 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 256 {
 257         return 0;
 258 }
 259 #endif
 260
 261 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 262 extern void scan_mapping_unevictable_pages(struct address_space *);
 263
 264 extern unsigned long scan_unevictable_pages;
 265 extern int scan_unevictable_handler(struct ctl_table *, int, struct file *,
 266                                         void __user *, size_t *, loff_t *);
 267 extern int scan_unevictable_register_node(struct node *node);
 268 extern void scan_unevictable_unregister_node(struct node *node);
 269
 270 extern int kswapd_run(int nid);
 271
 272 #ifdef CONFIG_MMU
 273 /* linux/mm/shmem.c */
 274 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 275 #endif /* CONFIG_MMU */
 276
 277 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 278
 279 #ifdef CONFIG_SWAP
 280 /* linux/mm/page_io.c */
 281 extern int swap_readpage(struct page *);
 282 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 283 extern void end_swap_bio_read(struct bio *bio, int err);
 284
 285 /* linux/mm/swap_state.c */
 286 extern struct address_space swapper_space;
 287 #define total_swapcache_pages  swapper_space.nrpages
 288 extern void show_swap_cache_info(void);
 289 extern int add_to_swap(struct page *);
 290 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 291 extern void __delete_from_swap_cache(struct page *);
 292 extern void delete_from_swap_cache(struct page *);
 293 extern void free_page_and_swap_cache(struct page *);
 294 extern void free_pages_and_swap_cache(struct page **, int);
 295 extern struct page *lookup_swap_cache(swp_entry_t);
 296 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 297                         struct vm_area_struct *vma, unsigned long addr);
 298 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 299                         struct vm_area_struct *vma, unsigned long addr);
 300
 301 /* linux/mm/swapfile.c */
 302 extern long nr_swap_pages;
 303 extern long total_swap_pages;
 304 extern void si_swapinfo(struct sysinfo *);
 305 extern swp_entry_t get_swap_page(void);
 306 extern swp_entry_t get_swap_page_of_type(int);
 307 extern void swap_duplicate(swp_entry_t);
 308 extern int swapcache_prepare(swp_entry_t);
 309 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 310 extern void swap_free(swp_entry_t);
 311 extern void swapcache_free(swp_entry_t, struct page *page);
 312 extern int free_swap_and_cache(swp_entry_t);
 313 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 314 extern unsigned int count_swap_pages(int, int);
 315 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 316 extern sector_t swapdev_block(int, pgoff_t);
 317 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 318 extern int reuse_swap_page(struct page *);
 319 extern int try_to_free_swap(struct page *);
 320 struct backing_dev_info;
 321
 322 /* linux/mm/thrash.c */
 323 extern struct mm_struct *swap_token_mm;
 324 extern void grab_swap_token(struct mm_struct *);
 325 extern void __put_swap_token(struct mm_struct *);
 326
 327 static inline int has_swap_token(struct mm_struct *mm)
 328 {
 329         return (mm == swap_token_mm);
 330 }
 331
 332 static inline void put_swap_token(struct mm_struct *mm)
 333 {
 334         if (has_swap_token(mm))
 335                 __put_swap_token(mm);
 336 }
 337
 338 static inline void disable_swap_token(void)
 339 {
 340         put_swap_token(swap_token_mm);
 341 }
 342
 343 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 344 extern void
 345 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 346 #else
 347 static inline void
 348 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 349 {
 350 }
 351 #endif
 352 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 353 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 354 #else
 355 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 356 {
 357 }
 358 #endif
 359
 360 #else /* CONFIG_SWAP */
 361
 362 #define nr_swap_pages                           0L
 363 #define total_swap_pages                        0L
 364 #define total_swapcache_pages                   0UL
 365
 366 #define si_swapinfo(val) \
 367         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 368 /* only sparc can not include linux/pagemap.h in this file
 369  * so leave page_cache_release and release_pages undeclared... */
 370 #define free_page_and_swap_cache(page) \
 371         page_cache_release(page)
 372 #define free_pages_and_swap_cache(pages, nr) \
 373         release_pages((pages), (nr), 0);
 374
 375 static inline void show_swap_cache_info(void)
 376 {
 377 }
 378
 379 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 380 #define swapcache_prepare(swp)          is_migration_entry(swp)
 381
 382 static inline void swap_duplicate(swp_entry_t swp)
 383 {
 384 }
 385
 386 static inline void swap_free(swp_entry_t swp)
 387 {
 388 }
 389
 390 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 391 {
 392 }
 393
 394 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 395                         struct vm_area_struct *vma, unsigned long addr)
 396 {
 397         return NULL;
 398 }
 399
 400 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 401 {
 402         return 0;
 403 }
 404
 405 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 406 {
 407         return NULL;
 408 }
 409
 410 static inline int add_to_swap(struct page *page)
 411 {
 412         return 0;
 413 }
 414
 415 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 416                                                         gfp_t gfp_mask)
 417 {
 418         return -1;
 419 }
 420
 421 static inline void __delete_from_swap_cache(struct page *page)
 422 {
 423 }
 424
 425 static inline void delete_from_swap_cache(struct page *page)
 426 {
 427 }
 428
 429 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 430
 431 static inline int try_to_free_swap(struct page *page)
 432 {
 433         return 0;
 434 }
 435
 436 static inline swp_entry_t get_swap_page(void)
 437 {
 438         swp_entry_t entry;
 439         entry.val = 0;
 440         return entry;
 441 }
 442
 443 /* linux/mm/thrash.c */
 444 #define put_swap_token(mm)      do { } while (0)
 445 #define grab_swap_token(mm)     do { } while (0)
 446 #define has_swap_token(mm)      0
 447 #define disable_swap_token()    do { } while (0)
 448
 449 static inline void
 450 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 451 {
 452 }
 453
 454 #endif /* CONFIG_SWAP */
 455 #endif /* __KERNEL__*/
 456 #endif /* _LINUX_SWAP_H */