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 long dirty_balance_reserve;
 211 extern unsigned int nr_free_buffer_pages(void);
 212 extern unsigned int nr_free_pagecache_pages(void);
 213
 214 /* Definition of global_page_state not available yet */
 215 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 216
 217
 218 /* linux/mm/swap.c */
 219 extern void __lru_cache_add(struct page *, enum lru_list lru);
 220 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 221 extern void lru_add_page_tail(struct zone* zone,
 222                               struct page *page, struct page *page_tail);
 223 extern void activate_page(struct page *);
 224 extern void mark_page_accessed(struct page *);
 225 extern void lru_add_drain(void);
 226 extern void lru_add_drain_cpu(int cpu);
 227 extern int lru_add_drain_all(void);
 228 extern void rotate_reclaimable_page(struct page *page);
 229 extern void deactivate_page(struct page *page);
 230 extern void swap_setup(void);
 231
 232 extern void add_page_to_unevictable_list(struct page *page);
 233
 234 /**
 235  * lru_cache_add: add a page to the page lists
 236  * @page: the page to add
 237  */
 238 static inline void lru_cache_add_anon(struct page *page)
 239 {
 240         __lru_cache_add(page, LRU_INACTIVE_ANON);
 241 }
 242
 243 static inline void lru_cache_add_file(struct page *page)
 244 {
 245         __lru_cache_add(page, LRU_INACTIVE_FILE);
 246 }
 247
 248 /* linux/mm/vmscan.c */
 249 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 250                                         gfp_t gfp_mask, nodemask_t *mask);
 251 extern int __isolate_lru_page(struct page *page, isolate_mode_t mode, int file);
 252 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 253                                                   gfp_t gfp_mask, bool noswap);
 254 extern unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *mem,
 255                                                 gfp_t gfp_mask, bool noswap,
 256                                                 struct zone *zone,
 257                                                 unsigned long *nr_scanned);
 258 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 259 extern int vm_swappiness;
 260 extern int remove_mapping(struct address_space *mapping, struct page *page);
 261 extern long vm_total_pages;
 262
 263 #ifdef CONFIG_NUMA
 264 extern int zone_reclaim_mode;
 265 extern int sysctl_min_unmapped_ratio;
 266 extern int sysctl_min_slab_ratio;
 267 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 268 #else
 269 #define zone_reclaim_mode 0
 270 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 271 {
 272         return 0;
 273 }
 274 #endif
 275
 276 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 277 extern void check_move_unevictable_pages(struct page **, int nr_pages);
 278
 279 extern unsigned long scan_unevictable_pages;
 280 extern int scan_unevictable_handler(struct ctl_table *, int,
 281                                         void __user *, size_t *, loff_t *);
 282 #ifdef CONFIG_NUMA
 283 extern int scan_unevictable_register_node(struct node *node);
 284 extern void scan_unevictable_unregister_node(struct node *node);
 285 #else
 286 static inline int scan_unevictable_register_node(struct node *node)
 287 {
 288         return 0;
 289 }
 290 static inline void scan_unevictable_unregister_node(struct node *node)
 291 {
 292 }
 293 #endif
 294
 295 extern int kswapd_run(int nid);
 296 extern void kswapd_stop(int nid);
 297 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 298 extern int mem_cgroup_swappiness(struct mem_cgroup *mem);
 299 #else
 300 static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 301 {
 302         return vm_swappiness;
 303 }
 304 #endif
 305 #ifdef CONFIG_SWAP
 306 /* linux/mm/page_io.c */
 307 extern int swap_readpage(struct page *);
 308 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 309 extern void end_swap_bio_read(struct bio *bio, int err);
 310
 311 /* linux/mm/swap_state.c */
 312 extern struct address_space swapper_space;
 313 #define total_swapcache_pages  swapper_space.nrpages
 314 extern void show_swap_cache_info(void);
 315 extern int add_to_swap(struct page *);
 316 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 317 extern void __delete_from_swap_cache(struct page *);
 318 extern void delete_from_swap_cache(struct page *);
 319 extern void free_page_and_swap_cache(struct page *);
 320 extern void free_pages_and_swap_cache(struct page **, int);
 321 extern struct page *lookup_swap_cache(swp_entry_t);
 322 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 323                         struct vm_area_struct *vma, unsigned long addr);
 324 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 325                         struct vm_area_struct *vma, unsigned long addr);
 326
 327 /* linux/mm/swapfile.c */
 328 extern long nr_swap_pages;
 329 extern long total_swap_pages;
 330 extern void si_swapinfo(struct sysinfo *);
 331 extern swp_entry_t get_swap_page(void);
 332 extern swp_entry_t get_swap_page_of_type(int);
 333 extern int add_swap_count_continuation(swp_entry_t, gfp_t);
 334 extern void swap_shmem_alloc(swp_entry_t);
 335 extern int swap_duplicate(swp_entry_t);
 336 extern int swapcache_prepare(swp_entry_t);
 337 extern void swap_free(swp_entry_t);
 338 extern void swapcache_free(swp_entry_t, struct page *page);
 339 extern int free_swap_and_cache(swp_entry_t);
 340 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 341 extern unsigned int count_swap_pages(int, int);
 342 extern sector_t map_swap_page(struct page *, struct block_device **);
 343 extern sector_t swapdev_block(int, pgoff_t);
 344 extern int reuse_swap_page(struct page *);
 345 extern int try_to_free_swap(struct page *);
 346 struct backing_dev_info;
 347
 348 /* linux/mm/thrash.c */
 349 extern struct mm_struct *swap_token_mm;
 350 extern void grab_swap_token(struct mm_struct *);
 351 extern void __put_swap_token(struct mm_struct *);
 352 extern void disable_swap_token(struct mem_cgroup *memcg);
 353
 354 static inline int has_swap_token(struct mm_struct *mm)
 355 {
 356         return (mm == swap_token_mm);
 357 }
 358
 359 static inline void put_swap_token(struct mm_struct *mm)
 360 {
 361         if (has_swap_token(mm))
 362                 __put_swap_token(mm);
 363 }
 364
 365 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 366 extern void
 367 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 368 extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep);
 369 #else
 370 static inline void
 371 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 372 {
 373 }
 374 #endif
 375 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 376 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 377 #else
 378 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 379 {
 380 }
 381 #endif
 382
 383 #else /* CONFIG_SWAP */
 384
 385 #define nr_swap_pages                           0L
 386 #define total_swap_pages                        0L
 387 #define total_swapcache_pages                   0UL
 388
 389 #define si_swapinfo(val) \
 390         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 391 /* only sparc can not include linux/pagemap.h in this file
 392  * so leave page_cache_release and release_pages undeclared... */
 393 #define free_page_and_swap_cache(page) \
 394         page_cache_release(page)
 395 #define free_pages_and_swap_cache(pages, nr) \
 396         release_pages((pages), (nr), 0);
 397
 398 static inline void show_swap_cache_info(void)
 399 {
 400 }
 401
 402 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 403 #define swapcache_prepare(swp)          is_migration_entry(swp)
 404
 405 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 406 {
 407         return 0;
 408 }
 409
 410 static inline void swap_shmem_alloc(swp_entry_t swp)
 411 {
 412 }
 413
 414 static inline int swap_duplicate(swp_entry_t swp)
 415 {
 416         return 0;
 417 }
 418
 419 static inline void swap_free(swp_entry_t swp)
 420 {
 421 }
 422
 423 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 424 {
 425 }
 426
 427 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 428                         struct vm_area_struct *vma, unsigned long addr)
 429 {
 430         return NULL;
 431 }
 432
 433 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 434 {
 435         return 0;
 436 }
 437
 438 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 439 {
 440         return NULL;
 441 }
 442
 443 static inline int add_to_swap(struct page *page)
 444 {
 445         return 0;
 446 }
 447
 448 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 449                                                         gfp_t gfp_mask)
 450 {
 451         return -1;
 452 }
 453
 454 static inline void __delete_from_swap_cache(struct page *page)
 455 {
 456 }
 457
 458 static inline void delete_from_swap_cache(struct page *page)
 459 {
 460 }
 461
 462 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 463
 464 static inline int try_to_free_swap(struct page *page)
 465 {
 466         return 0;
 467 }
 468
 469 static inline swp_entry_t get_swap_page(void)
 470 {
 471         swp_entry_t entry;
 472         entry.val = 0;
 473         return entry;
 474 }
 475
 476 /* linux/mm/thrash.c */
 477 static inline void put_swap_token(struct mm_struct *mm)
 478 {
 479 }
 480
 481 static inline void grab_swap_token(struct mm_struct *mm)
 482 {
 483 }
 484
 485 static inline int has_swap_token(struct mm_struct *mm)
 486 {
 487         return 0;
 488 }
 489
 490 static inline void disable_swap_token(struct mem_cgroup *memcg)
 491 {
 492 }
 493
 494 static inline void
 495 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 496 {
 497 }
 498
 499 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 500 static inline int
 501 mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep)
 502 {
 503         return 0;
 504 }
 505 #endif
 506
 507 #endif /* CONFIG_SWAP */
 508 #endif /* __KERNEL__*/
 509 #endif /* _LINUX_SWAP_H */