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 unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 243                                                 gfp_t gfp_mask, bool noswap,
 244                                                 unsigned int swappiness,
 245                                                 struct zone *zone,
 246                                                 int nid);
 247 extern int __isolate_lru_page(struct page *page, int mode, int file);
 248 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 249 extern int vm_swappiness;
 250 extern int remove_mapping(struct address_space *mapping, struct page *page);
 251 extern long vm_total_pages;
 252
 253 #ifdef CONFIG_NUMA
 254 extern int zone_reclaim_mode;
 255 extern int sysctl_min_unmapped_ratio;
 256 extern int sysctl_min_slab_ratio;
 257 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 258 #else
 259 #define zone_reclaim_mode 0
 260 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 261 {
 262         return 0;
 263 }
 264 #endif
 265
 266 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 267 extern void scan_mapping_unevictable_pages(struct address_space *);
 268
 269 extern unsigned long scan_unevictable_pages;
 270 extern int scan_unevictable_handler(struct ctl_table *, int,
 271                                         void __user *, size_t *, loff_t *);
 272 extern int scan_unevictable_register_node(struct node *node);
 273 extern void scan_unevictable_unregister_node(struct node *node);
 274
 275 extern int kswapd_run(int nid);
 276 extern void kswapd_stop(int nid);
 277
 278 #ifdef CONFIG_MMU
 279 /* linux/mm/shmem.c */
 280 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 281 #endif /* CONFIG_MMU */
 282
 283 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 284
 285 #ifdef CONFIG_SWAP
 286 /* linux/mm/page_io.c */
 287 extern int swap_readpage(struct page *);
 288 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 289 extern void end_swap_bio_read(struct bio *bio, int err);
 290
 291 /* linux/mm/swap_state.c */
 292 extern struct address_space swapper_space;
 293 #define total_swapcache_pages  swapper_space.nrpages
 294 extern void show_swap_cache_info(void);
 295 extern int add_to_swap(struct page *);
 296 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 297 extern void __delete_from_swap_cache(struct page *);
 298 extern void delete_from_swap_cache(struct page *);
 299 extern void free_page_and_swap_cache(struct page *);
 300 extern void free_pages_and_swap_cache(struct page **, int);
 301 extern struct page *lookup_swap_cache(swp_entry_t);
 302 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 303                         struct vm_area_struct *vma, unsigned long addr);
 304 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 305                         struct vm_area_struct *vma, unsigned long addr);
 306
 307 /* linux/mm/swapfile.c */
 308 extern long nr_swap_pages;
 309 extern long total_swap_pages;
 310 extern void si_swapinfo(struct sysinfo *);
 311 extern swp_entry_t get_swap_page(void);
 312 extern swp_entry_t get_swap_page_of_type(int);
 313 extern void swap_duplicate(swp_entry_t);
 314 extern int swapcache_prepare(swp_entry_t);
 315 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 316 extern void swap_free(swp_entry_t);
 317 extern void swapcache_free(swp_entry_t, struct page *page);
 318 extern int free_swap_and_cache(swp_entry_t);
 319 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 320 extern unsigned int count_swap_pages(int, int);
 321 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 322 extern sector_t swapdev_block(int, pgoff_t);
 323 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 324 extern int reuse_swap_page(struct page *);
 325 extern int try_to_free_swap(struct page *);
 326 struct backing_dev_info;
 327
 328 /* linux/mm/thrash.c */
 329 extern struct mm_struct *swap_token_mm;
 330 extern void grab_swap_token(struct mm_struct *);
 331 extern void __put_swap_token(struct mm_struct *);
 332
 333 static inline int has_swap_token(struct mm_struct *mm)
 334 {
 335         return (mm == swap_token_mm);
 336 }
 337
 338 static inline void put_swap_token(struct mm_struct *mm)
 339 {
 340         if (has_swap_token(mm))
 341                 __put_swap_token(mm);
 342 }
 343
 344 static inline void disable_swap_token(void)
 345 {
 346         put_swap_token(swap_token_mm);
 347 }
 348
 349 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 350 extern void
 351 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 352 #else
 353 static inline void
 354 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 355 {
 356 }
 357 #endif
 358 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 359 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 360 #else
 361 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 362 {
 363 }
 364 #endif
 365
 366 #else /* CONFIG_SWAP */
 367
 368 #define nr_swap_pages                           0L
 369 #define total_swap_pages                        0L
 370 #define total_swapcache_pages                   0UL
 371
 372 #define si_swapinfo(val) \
 373         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 374 /* only sparc can not include linux/pagemap.h in this file
 375  * so leave page_cache_release and release_pages undeclared... */
 376 #define free_page_and_swap_cache(page) \
 377         page_cache_release(page)
 378 #define free_pages_and_swap_cache(pages, nr) \
 379         release_pages((pages), (nr), 0);
 380
 381 static inline void show_swap_cache_info(void)
 382 {
 383 }
 384
 385 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 386 #define swapcache_prepare(swp)          is_migration_entry(swp)
 387
 388 static inline void swap_duplicate(swp_entry_t swp)
 389 {
 390 }
 391
 392 static inline void swap_free(swp_entry_t swp)
 393 {
 394 }
 395
 396 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 397 {
 398 }
 399
 400 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 401                         struct vm_area_struct *vma, unsigned long addr)
 402 {
 403         return NULL;
 404 }
 405
 406 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 407 {
 408         return 0;
 409 }
 410
 411 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 412 {
 413         return NULL;
 414 }
 415
 416 static inline int add_to_swap(struct page *page)
 417 {
 418         return 0;
 419 }
 420
 421 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 422                                                         gfp_t gfp_mask)
 423 {
 424         return -1;
 425 }
 426
 427 static inline void __delete_from_swap_cache(struct page *page)
 428 {
 429 }
 430
 431 static inline void delete_from_swap_cache(struct page *page)
 432 {
 433 }
 434
 435 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 436
 437 static inline int try_to_free_swap(struct page *page)
 438 {
 439         return 0;
 440 }
 441
 442 static inline swp_entry_t get_swap_page(void)
 443 {
 444         swp_entry_t entry;
 445         entry.val = 0;
 446         return entry;
 447 }
 448
 449 /* linux/mm/thrash.c */
 450 static inline void put_swap_token(struct mm_struct *mm)
 451 {
 452 }
 453
 454 static inline void grab_swap_token(struct mm_struct *mm)
 455 {
 456 }
 457
 458 static inline int has_swap_token(struct mm_struct *mm)
 459 {
 460         return 0;
 461 }
 462
 463 static inline void disable_swap_token(void)
 464 {
 465 }
 466
 467 static inline void
 468 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 469 {
 470 }
 471
 472 #endif /* CONFIG_SWAP */
 473 #endif /* __KERNEL__*/
 474 #endif /* _LINUX_SWAP_H */