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 <linux/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 #define SWAP_FLAG_DISCARD       0x10000 /* discard swap cluster after use */
  23
  24 static inline int current_is_kswapd(void)
  25 {
  26         return current->flags & PF_KSWAPD;
  27 }
  28
  29 /*
  30  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  31  * be swapped to.  The swap type and the offset into that swap type are
  32  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  33  * for the type means that the maximum number of swapcache pages is 27 bits
  34  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  35  * the type/offset into the pte as 5/27 as well.
  36  */
  37 #define MAX_SWAPFILES_SHIFT     5
  38
  39 /*
  40  * Use some of the swap files numbers for other purposes. This
  41  * is a convenient way to hook into the VM to trigger special
  42  * actions on faults.
  43  */
  44
  45 /*
  46  * NUMA node memory migration support
  47  */
  48 #ifdef CONFIG_MIGRATION
  49 #define SWP_MIGRATION_NUM 2
  50 #define SWP_MIGRATION_READ      (MAX_SWAPFILES + SWP_HWPOISON_NUM)
  51 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
  52 #else
  53 #define SWP_MIGRATION_NUM 0
  54 #endif
  55
  56 /*
  57  * Handling of hardware poisoned pages with memory corruption.
  58  */
  59 #ifdef CONFIG_MEMORY_FAILURE
  60 #define SWP_HWPOISON_NUM 1
  61 #define SWP_HWPOISON            MAX_SWAPFILES
  62 #else
  63 #define SWP_HWPOISON_NUM 0
  64 #endif
  65
  66 #define MAX_SWAPFILES \
  67         ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
  68
  69 /*
  70  * Magic header for a swap area. The first part of the union is
  71  * what the swap magic looks like for the old (limited to 128MB)
  72  * swap area format, the second part of the union adds - in the
  73  * old reserved area - some extra information. Note that the first
  74  * kilobyte is reserved for boot loader or disk label stuff...
  75  *
  76  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  77  * areas somewhat tricky on machines that support multiple page sizes.
  78  * For 2.5 we'll probably want to move the magic to just beyond the
  79  * bootbits...
  80  */
  81 union swap_header {
  82         struct {
  83                 char reserved[PAGE_SIZE - 10];
  84                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  85         } magic;
  86         struct {
  87                 char            bootbits[1024]; /* Space for disklabel etc. */
  88                 __u32           version;
  89                 __u32           last_page;
  90                 __u32           nr_badpages;
  91                 unsigned char   sws_uuid[16];
  92                 unsigned char   sws_volume[16];
  93                 __u32           padding[117];
  94                 __u32           badpages[1];
  95         } info;
  96 };
  97
  98  /* A swap entry has to fit into a "unsigned long", as
  99   * the entry is hidden in the "index" field of the
 100   * swapper address space.
 101   */
 102 typedef struct {
 103         unsigned long val;
 104 } swp_entry_t;
 105
 106 /*
 107  * current->reclaim_state points to one of these when a task is running
 108  * memory reclaim
 109  */
 110 struct reclaim_state {
 111         unsigned long reclaimed_slab;
 112 };
 113
 114 #ifdef __KERNEL__
 115
 116 struct address_space;
 117 struct sysinfo;
 118 struct writeback_control;
 119 struct zone;
 120
 121 /*
 122  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 123  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 124  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 125  * from setup, they're handled identically.
 126  *
 127  * We always assume that blocks are of size PAGE_SIZE.
 128  */
 129 struct swap_extent {
 130         struct list_head list;
 131         pgoff_t start_page;
 132         pgoff_t nr_pages;
 133         sector_t start_block;
 134 };
 135
 136 /*
 137  * Max bad pages in the new format..
 138  */
 139 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 140 #define MAX_SWAP_BADPAGES \
 141         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 142
 143 enum {
 144         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 145         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 146         SWP_DISCARDABLE = (1 << 2),     /* swapon+blkdev support discard */
 147         SWP_DISCARDING  = (1 << 3),     /* now discarding a free cluster */
 148         SWP_SOLIDSTATE  = (1 << 4),     /* blkdev seeks are cheap */
 149         SWP_CONTINUED   = (1 << 5),     /* swap_map has count continuation */
 150         SWP_BLKDEV      = (1 << 6),     /* its a block device */
 151                                         /* add others here before... */
 152         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 153 };
 154
 155 #define SWAP_CLUSTER_MAX 32
 156 #define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
 157
 158 /*
 159  * Ratio between the present memory in the zone and the "gap" that
 160  * we're allowing kswapd to shrink in addition to the per-zone high
 161  * wmark, even for zones that already have the high wmark satisfied,
 162  * in order to provide better per-zone lru behavior. We are ok to
 163  * spend not more than 1% of the memory for this zone balancing "gap".
 164  */
 165 #define KSWAPD_ZONE_BALANCE_GAP_RATIO 100
 166
 167 #define SWAP_MAP_MAX    0x3e    /* Max duplication count, in first swap_map */
 168 #define SWAP_MAP_BAD    0x3f    /* Note pageblock is bad, in first swap_map */
 169 #define SWAP_HAS_CACHE  0x40    /* Flag page is cached, in first swap_map */
 170 #define SWAP_CONT_MAX   0x7f    /* Max count, in each swap_map continuation */
 171 #define COUNT_CONTINUED 0x80    /* See swap_map continuation for full count */
 172 #define SWAP_MAP_SHMEM  0xbf    /* Owned by shmem/tmpfs, in first swap_map */
 173
 174 /*
 175  * The in-memory structure used to track swap areas.
 176  */
 177 struct swap_info_struct {
 178         unsigned long   flags;          /* SWP_USED etc: see above */
 179         signed short    prio;           /* swap priority of this type */
 180         signed char     type;           /* strange name for an index */
 181         signed char     next;           /* next type on the swap list */
 182         unsigned int    max;            /* extent of the swap_map */
 183         unsigned char *swap_map;        /* vmalloc'ed array of usage counts */
 184         unsigned int lowest_bit;        /* index of first free in swap_map */
 185         unsigned int highest_bit;       /* index of last free in swap_map */
 186         unsigned int pages;             /* total of usable pages of swap */
 187         unsigned int inuse_pages;       /* number of those currently in use */
 188         unsigned int cluster_next;      /* likely index for next allocation */
 189         unsigned int cluster_nr;        /* countdown to next cluster search */
 190         unsigned int lowest_alloc;      /* while preparing discard cluster */
 191         unsigned int highest_alloc;     /* while preparing discard cluster */
 192         struct swap_extent *curr_swap_extent;
 193         struct swap_extent first_swap_extent;
 194         struct block_device *bdev;      /* swap device or bdev of swap file */
 195         struct file *swap_file;         /* seldom referenced */
 196         unsigned int old_block_size;    /* seldom referenced */
 197 };
 198
 199 struct swap_list_t {
 200         int head;       /* head of priority-ordered swapfile list */
 201         int next;       /* swapfile to be used next */
 202 };
 203
 204 /* Swap 50% full? Release swapcache more aggressively.. */
 205 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 206
 207 /* linux/mm/page_alloc.c */
 208 extern unsigned long totalram_pages;
 209 extern unsigned long totalreserve_pages;
 210 extern unsigned int nr_free_buffer_pages(void);
 211 extern unsigned int nr_free_pagecache_pages(void);
 212
 213 /* Definition of global_page_state not available yet */
 214 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 215
 216
 217 /* linux/mm/swap.c */
 218 extern void __lru_cache_add(struct page *, enum lru_list lru);
 219 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 220 extern void lru_add_page_tail(struct zone* zone,
 221                               struct page *page, struct page *page_tail);
 222 extern void activate_page(struct page *);
 223 extern void mark_page_accessed(struct page *);
 224 extern void lru_add_drain(void);
 225 extern int lru_add_drain_all(void);
 226 extern void rotate_reclaimable_page(struct page *page);
 227 extern void deactivate_page(struct page *page);
 228 extern void swap_setup(void);
 229
 230 extern void add_page_to_unevictable_list(struct page *page);
 231
 232 /**
 233  * lru_cache_add: add a page to the page lists
 234  * @page: the page to add
 235  */
 236 static inline void lru_cache_add_anon(struct page *page)
 237 {
 238         __lru_cache_add(page, LRU_INACTIVE_ANON);
 239 }
 240
 241 static inline void lru_cache_add_file(struct page *page)
 242 {
 243         __lru_cache_add(page, LRU_INACTIVE_FILE);
 244 }
 245
 246 /* LRU Isolation modes. */
 247 #define ISOLATE_INACTIVE 0      /* Isolate inactive pages. */
 248 #define ISOLATE_ACTIVE 1        /* Isolate active pages. */
 249 #define ISOLATE_BOTH 2          /* Isolate both active and inactive pages. */
 250
 251 /* linux/mm/vmscan.c */
 252 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 253                                         gfp_t gfp_mask, nodemask_t *mask);
 254 extern int __isolate_lru_page(struct page *page, int mode, int file);
 255 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 256                                                   gfp_t gfp_mask, bool noswap);
 257 extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 258                                                 gfp_t gfp_mask, bool noswap,
 259                                                 struct zone *zone,
 260                                                 unsigned long *nr_scanned);
 261 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 262 extern int vm_swappiness;
 263 extern int remove_mapping(struct address_space *mapping, struct page *page);
 264 extern long vm_total_pages;
 265
 266 #ifdef CONFIG_NUMA
 267 extern int zone_reclaim_mode;
 268 extern int sysctl_min_unmapped_ratio;
 269 extern int sysctl_min_slab_ratio;
 270 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 271 #else
 272 #define zone_reclaim_mode 0
 273 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 274 {
 275         return 0;
 276 }
 277 #endif
 278
 279 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 280 extern void scan_mapping_unevictable_pages(struct address_space *);
 281
 282 extern unsigned long scan_unevictable_pages;
 283 extern int scan_unevictable_handler(struct ctl_table *, int,
 284                                         void __user *, size_t *, loff_t *);
 285 #ifdef CONFIG_NUMA
 286 extern int scan_unevictable_register_node(struct node *node);
 287 extern void scan_unevictable_unregister_node(struct node *node);
 288 #else
 289 static inline int scan_unevictable_register_node(struct node *node)
 290 {
 291         return 0;
 292 }
 293 static inline void scan_unevictable_unregister_node(struct node *node)
 294 {
 295 }
 296 #endif
 297
 298 extern int kswapd_run(int nid);
 299 extern void kswapd_stop(int nid);
 300 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 301 extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
 302 #else
 303 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 304 {
 305         return vm_swappiness;
 306 }
 307 #endif
 308 #ifdef CONFIG_SWAP
 309 /* linux/mm/page_io.c */
 310 extern int swap_readpage(struct page *);
 311 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 312 extern void end_swap_bio_read(struct bio *bio, int err);
 313
 314 /* linux/mm/swap_state.c */
 315 extern struct address_space swapper_space;
 316 #define total_swapcache_pages  swapper_space.nrpages
 317 extern void show_swap_cache_info(void);
 318 extern int add_to_swap(struct page *);
 319 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 320 extern void __delete_from_swap_cache(struct page *);
 321 extern void delete_from_swap_cache(struct page *);
 322 extern void free_page_and_swap_cache(struct page *);
 323 extern void free_pages_and_swap_cache(struct page **, int);
 324 extern struct page *lookup_swap_cache(swp_entry_t);
 325 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 326                         struct vm_area_struct *vma, unsigned long addr);
 327 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 328                         struct vm_area_struct *vma, unsigned long addr);
 329
 330 /* linux/mm/swapfile.c */
 331 extern long nr_swap_pages;
 332 extern long total_swap_pages;
 333 extern void si_swapinfo(struct sysinfo *);
 334 extern swp_entry_t get_swap_page(void);
 335 extern swp_entry_t get_swap_page_of_type(int);
 336 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 337 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 338 extern void swap_shmem_alloc(swp_entry_t);
 339 extern int swap_duplicate(swp_entry_t);
 340 extern int swapcache_prepare(swp_entry_t);
 341 extern void swap_free(swp_entry_t);
 342 extern void swapcache_free(swp_entry_t, struct page *page);
 343 extern int free_swap_and_cache(swp_entry_t);
 344 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 345 extern unsigned int count_swap_pages(int, int);
 346 extern sector_t map_swap_page(struct page *, struct block_device **);
 347 extern sector_t swapdev_block(int, pgoff_t);
 348 extern int reuse_swap_page(struct page *);
 349 extern int try_to_free_swap(struct page *);
 350 struct backing_dev_info;
 351
 352 /* linux/mm/thrash.c */
 353 extern struct mm_struct *swap_token_mm;
 354 extern void grab_swap_token(struct mm_struct *);
 355 extern void __put_swap_token(struct mm_struct *);
 356 extern void disable_swap_token(struct mem_cgroup *memcg);
 357
 358 static inline int has_swap_token(struct mm_struct *mm)
 359 {
 360         return (mm == swap_token_mm);
 361 }
 362
 363 static inline void put_swap_token(struct mm_struct *mm)
 364 {
 365         if (has_swap_token(mm))
 366                 __put_swap_token(mm);
 367 }
 368
 369 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 370 extern void
 371 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 372 extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep);
 373 #else
 374 static inline void
 375 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 376 {
 377 }
 378 #endif
 379 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 380 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 381 #else
 382 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 383 {
 384 }
 385 #endif
 386
 387 #else /* CONFIG_SWAP */
 388
 389 #define nr_swap_pages                           0L
 390 #define total_swap_pages                        0L
 391 #define total_swapcache_pages                   0UL
 392
 393 #define si_swapinfo(val) \
 394         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 395 /* only sparc can not include linux/pagemap.h in this file
 396  * so leave page_cache_release and release_pages undeclared... */
 397 #define free_page_and_swap_cache(page) \
 398         page_cache_release(page)
 399 #define free_pages_and_swap_cache(pages, nr) \
 400         release_pages((pages), (nr), 0);
 401
 402 static inline void show_swap_cache_info(void)
 403 {
 404 }
 405
 406 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 407 #define swapcache_prepare(swp)          is_migration_entry(swp)
 408
 409 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 410 {
 411         return 0;
 412 }
 413
 414 static inline void swap_shmem_alloc(swp_entry_t swp)
 415 {
 416 }
 417
 418 static inline int swap_duplicate(swp_entry_t swp)
 419 {
 420         return 0;
 421 }
 422
 423 static inline void swap_free(swp_entry_t swp)
 424 {
 425 }
 426
 427 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 428 {
 429 }
 430
 431 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 432                         struct vm_area_struct *vma, unsigned long addr)
 433 {
 434         return NULL;
 435 }
 436
 437 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 438 {
 439         return 0;
 440 }
 441
 442 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 443 {
 444         return NULL;
 445 }
 446
 447 static inline int add_to_swap(struct page *page)
 448 {
 449         return 0;
 450 }
 451
 452 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 453                                                         gfp_t gfp_mask)
 454 {
 455         return -1;
 456 }
 457
 458 static inline void __delete_from_swap_cache(struct page *page)
 459 {
 460 }
 461
 462 static inline void delete_from_swap_cache(struct page *page)
 463 {
 464 }
 465
 466 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 467
 468 static inline int try_to_free_swap(struct page *page)
 469 {
 470         return 0;
 471 }
 472
 473 static inline swp_entry_t get_swap_page(void)
 474 {
 475         swp_entry_t entry;
 476         entry.val = 0;
 477         return entry;
 478 }
 479
 480 /* linux/mm/thrash.c */
 481 static inline void put_swap_token(struct mm_struct *mm)
 482 {
 483 }
 484
 485 static inline void grab_swap_token(struct mm_struct *mm)
 486 {
 487 }
 488
 489 static inline int has_swap_token(struct mm_struct *mm)
 490 {
 491         return 0;
 492 }
 493
 494 static inline void disable_swap_token(struct mem_cgroup *memcg)
 495 {
 496 }
 497
 498 static inline void
 499 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 500 {
 501 }
 502
 503 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 504 static inline int
 505 mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
 506 {
 507         return 0;
 508 }
 509 #endif
 510
 511 #endif /* CONFIG_SWAP */
 512 #endif /* __KERNEL__*/
 513 #endif /* _LINUX_SWAP_H */