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