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         SWP_CONTINUED   = (1 << 5),     /* swap_map has count continuation */
 149         SWP_BLKDEV      = (1 << 6),     /* its a block device */
 150                                         /* add others here before... */
 151         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 152 };
 153
 154 #define SWAP_CLUSTER_MAX 32
 155
 156 #define SWAP_MAP_MAX    0x3e    /* Max duplication count, in first swap_map */
 157 #define SWAP_MAP_BAD    0x3f    /* Note pageblock is bad, in first swap_map */
 158 #define SWAP_HAS_CACHE  0x40    /* Flag page is cached, in first swap_map */
 159 #define SWAP_CONT_MAX   0x7f    /* Max count, in each swap_map continuation */
 160 #define COUNT_CONTINUED 0x80    /* See swap_map continuation for full count */
 161 #define SWAP_MAP_SHMEM  0xbf    /* Owned by shmem/tmpfs, in first swap_map */
 162
 163 /*
 164  * The in-memory structure used to track swap areas.
 165  */
 166 struct swap_info_struct {
 167         unsigned long   flags;          /* SWP_USED etc: see above */
 168         signed short    prio;           /* swap priority of this type */
 169         signed char     type;           /* strange name for an index */
 170         signed char     next;           /* next type on the swap list */
 171         unsigned int    max;            /* extent of the swap_map */
 172         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 173         unsigned int lowest_bit;        /* index of first free in swap_map */
 174         unsigned int highest_bit;       /* index of last free in swap_map */
 175         unsigned int pages;             /* total of usable pages of swap */
 176         unsigned int inuse_pages;       /* number of those currently in use */
 177         unsigned int cluster_next;      /* likely index for next allocation */
 178         unsigned int cluster_nr;        /* countdown to next cluster search */
 179         unsigned int lowest_alloc;      /* while preparing discard cluster */
 180         unsigned int highest_alloc;     /* while preparing discard cluster */
 181         struct swap_extent *curr_swap_extent;
 182         struct swap_extent first_swap_extent;
 183         struct block_device *bdev;      /* swap device or bdev of swap file */
 184         struct file *swap_file;         /* seldom referenced */
 185         unsigned int old_block_size;    /* seldom referenced */
 186 };
 187
 188 struct swap_list_t {
 189         int head;       /* head of priority-ordered swapfile list */
 190         int next;       /* swapfile to be used next */
 191 };
 192
 193 /* Swap 50% full? Release swapcache more aggressively.. */
 194 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 195
 196 /* linux/mm/page_alloc.c */
 197 extern unsigned long totalram_pages;
 198 extern unsigned long totalreserve_pages;
 199 extern unsigned int nr_free_buffer_pages(void);
 200 extern unsigned int nr_free_pagecache_pages(void);
 201
 202 /* Definition of global_page_state not available yet */
 203 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 204
 205
 206 /* linux/mm/swap.c */
 207 extern void __lru_cache_add(struct page *, enum lru_list lru);
 208 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 209 extern void activate_page(struct page *);
 210 extern void mark_page_accessed(struct page *);
 211 extern void lru_add_drain(void);
 212 extern int lru_add_drain_all(void);
 213 extern void rotate_reclaimable_page(struct page *page);
 214 extern void swap_setup(void);
 215
 216 extern void add_page_to_unevictable_list(struct page *page);
 217
 218 /**
 219  * lru_cache_add: add a page to the page lists
 220  * @page: the page to add
 221  */
 222 static inline void lru_cache_add_anon(struct page *page)
 223 {
 224         __lru_cache_add(page, LRU_INACTIVE_ANON);
 225 }
 226
 227 static inline void lru_cache_add_file(struct page *page)
 228 {
 229         __lru_cache_add(page, LRU_INACTIVE_FILE);
 230 }
 231
 232 /* linux/mm/vmscan.c */
 233 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 234                                         gfp_t gfp_mask, nodemask_t *mask);
 235 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 236                                                   gfp_t gfp_mask, bool noswap,
 237                                                   unsigned int swappiness);
 238 extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 239                                                 gfp_t gfp_mask, bool noswap,
 240                                                 unsigned int swappiness,
 241                                                 struct zone *zone,
 242                                                 int nid);
 243 extern int __isolate_lru_page(struct page *page, int mode, int file);
 244 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 245 extern int vm_swappiness;
 246 extern int remove_mapping(struct address_space *mapping, struct page *page);
 247 extern long vm_total_pages;
 248
 249 #ifdef CONFIG_NUMA
 250 extern int zone_reclaim_mode;
 251 extern int sysctl_min_unmapped_ratio;
 252 extern int sysctl_min_slab_ratio;
 253 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 254 #else
 255 #define zone_reclaim_mode 0
 256 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 257 {
 258         return 0;
 259 }
 260 #endif
 261
 262 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 263 extern void scan_mapping_unevictable_pages(struct address_space *);
 264
 265 extern unsigned long scan_unevictable_pages;
 266 extern int scan_unevictable_handler(struct ctl_table *, int,
 267                                         void __user *, size_t *, loff_t *);
 268 extern int scan_unevictable_register_node(struct node *node);
 269 extern void scan_unevictable_unregister_node(struct node *node);
 270
 271 extern int kswapd_run(int nid);
 272 extern void kswapd_stop(int nid);
 273
 274 #ifdef CONFIG_MMU
 275 /* linux/mm/shmem.c */
 276 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 277 #endif /* CONFIG_MMU */
 278
 279 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 280
 281 #ifdef CONFIG_SWAP
 282 /* linux/mm/page_io.c */
 283 extern int swap_readpage(struct page *);
 284 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 285 extern void end_swap_bio_read(struct bio *bio, int err);
 286
 287 /* linux/mm/swap_state.c */
 288 extern struct address_space swapper_space;
 289 #define total_swapcache_pages  swapper_space.nrpages
 290 extern void show_swap_cache_info(void);
 291 extern int add_to_swap(struct page *);
 292 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 293 extern void __delete_from_swap_cache(struct page *);
 294 extern void delete_from_swap_cache(struct page *);
 295 extern void free_page_and_swap_cache(struct page *);
 296 extern void free_pages_and_swap_cache(struct page **, int);
 297 extern struct page *lookup_swap_cache(swp_entry_t);
 298 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 299                         struct vm_area_struct *vma, unsigned long addr);
 300 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 301                         struct vm_area_struct *vma, unsigned long addr);
 302
 303 /* linux/mm/swapfile.c */
 304 extern long nr_swap_pages;
 305 extern long total_swap_pages;
 306 extern void si_swapinfo(struct sysinfo *);
 307 extern swp_entry_t get_swap_page(void);
 308 extern swp_entry_t get_swap_page_of_type(int);
 309 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 310 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 311 extern void swap_shmem_alloc(swp_entry_t);
 312 extern int swap_duplicate(swp_entry_t);
 313 extern int swapcache_prepare(swp_entry_t);
 314 extern void swap_free(swp_entry_t);
 315 extern void swapcache_free(swp_entry_t, struct page *page);
 316 extern int free_swap_and_cache(swp_entry_t);
 317 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 318 extern unsigned int count_swap_pages(int, int);
 319 extern sector_t map_swap_page(struct page *, struct block_device **);
 320 extern sector_t swapdev_block(int, pgoff_t);
 321 extern int reuse_swap_page(struct page *);
 322 extern int try_to_free_swap(struct page *);
 323 struct backing_dev_info;
 324
 325 /* linux/mm/thrash.c */
 326 extern struct mm_struct *swap_token_mm;
 327 extern void grab_swap_token(struct mm_struct *);
 328 extern void __put_swap_token(struct mm_struct *);
 329
 330 static inline int has_swap_token(struct mm_struct *mm)
 331 {
 332         return (mm == swap_token_mm);
 333 }
 334
 335 static inline void put_swap_token(struct mm_struct *mm)
 336 {
 337         if (has_swap_token(mm))
 338                 __put_swap_token(mm);
 339 }
 340
 341 static inline void disable_swap_token(void)
 342 {
 343         put_swap_token(swap_token_mm);
 344 }
 345
 346 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 347 extern void
 348 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 349 extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep);
 350 #else
 351 static inline void
 352 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 353 {
 354 }
 355 #endif
 356 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 357 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 358 #else
 359 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 360 {
 361 }
 362 #endif
 363
 364 #else /* CONFIG_SWAP */
 365
 366 #define nr_swap_pages                           0L
 367 #define total_swap_pages                        0L
 368 #define total_swapcache_pages                   0UL
 369
 370 #define si_swapinfo(val) \
 371         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 372 /* only sparc can not include linux/pagemap.h in this file
 373  * so leave page_cache_release and release_pages undeclared... */
 374 #define free_page_and_swap_cache(page) \
 375         page_cache_release(page)
 376 #define free_pages_and_swap_cache(pages, nr) \
 377         release_pages((pages), (nr), 0);
 378
 379 static inline void show_swap_cache_info(void)
 380 {
 381 }
 382
 383 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 384 #define swapcache_prepare(swp)          is_migration_entry(swp)
 385
 386 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 387 {
 388         return 0;
 389 }
 390
 391 static inline void swap_shmem_alloc(swp_entry_t swp)
 392 {
 393 }
 394
 395 static inline int swap_duplicate(swp_entry_t swp)
 396 {
 397         return 0;
 398 }
 399
 400 static inline void swap_free(swp_entry_t swp)
 401 {
 402 }
 403
 404 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 405 {
 406 }
 407
 408 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 409                         struct vm_area_struct *vma, unsigned long addr)
 410 {
 411         return NULL;
 412 }
 413
 414 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 415 {
 416         return 0;
 417 }
 418
 419 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 420 {
 421         return NULL;
 422 }
 423
 424 static inline int add_to_swap(struct page *page)
 425 {
 426         return 0;
 427 }
 428
 429 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 430                                                         gfp_t gfp_mask)
 431 {
 432         return -1;
 433 }
 434
 435 static inline void __delete_from_swap_cache(struct page *page)
 436 {
 437 }
 438
 439 static inline void delete_from_swap_cache(struct page *page)
 440 {
 441 }
 442
 443 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 444
 445 static inline int try_to_free_swap(struct page *page)
 446 {
 447         return 0;
 448 }
 449
 450 static inline swp_entry_t get_swap_page(void)
 451 {
 452         swp_entry_t entry;
 453         entry.val = 0;
 454         return entry;
 455 }
 456
 457 /* linux/mm/thrash.c */
 458 static inline void put_swap_token(struct mm_struct *mm)
 459 {
 460 }
 461
 462 static inline void grab_swap_token(struct mm_struct *mm)
 463 {
 464 }
 465
 466 static inline int has_swap_token(struct mm_struct *mm)
 467 {
 468         return 0;
 469 }
 470
 471 static inline void disable_swap_token(void)
 472 {
 473 }
 474
 475 static inline void
 476 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 477 {
 478 }
 479
 480 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 481 static inline int
 482 mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
 483 {
 484         return 0;
 485 }
 486 #endif
 487
 488 #endif /* CONFIG_SWAP */
 489 #endif /* __KERNEL__*/
 490 #endif /* _LINUX_SWAP_H */