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(void);
 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 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent);
 323 #else
 324 static inline void
 325 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 326 {
 327 }
 328 #endif
 329 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 330 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 331 #else
 332 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 333 {
 334 }
 335 #endif
 336
 337 #else /* CONFIG_SWAP */
 338
 339 #define nr_swap_pages                           0L
 340 #define total_swap_pages                        0L
 341 #define total_swapcache_pages                   0UL
 342
 343 #define si_swapinfo(val) \
 344         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 345 /* only sparc can not include linux/pagemap.h in this file
 346  * so leave page_cache_release and release_pages undeclared... */
 347 #define free_page_and_swap_cache(page) \
 348         page_cache_release(page)
 349 #define free_pages_and_swap_cache(pages, nr) \
 350         release_pages((pages), (nr), 0);
 351
 352 static inline void show_swap_cache_info(void)
 353 {
 354 }
 355
 356 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 357 #define swapcache_prepare(swp)          is_migration_entry(swp)
 358
 359 static inline void swap_duplicate(swp_entry_t swp)
 360 {
 361 }
 362
 363 static inline void swap_free(swp_entry_t swp)
 364 {
 365 }
 366
 367 static inline void swapcache_free(swp_entry_t swp, struct page *page)
 368 {
 369 }
 370
 371 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 372                         struct vm_area_struct *vma, unsigned long addr)
 373 {
 374         return NULL;
 375 }
 376
 377 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 378 {
 379         return 0;
 380 }
 381
 382 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 383 {
 384         return NULL;
 385 }
 386
 387 static inline int add_to_swap(struct page *page)
 388 {
 389         return 0;
 390 }
 391
 392 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 393                                                         gfp_t gfp_mask)
 394 {
 395         return -1;
 396 }
 397
 398 static inline void __delete_from_swap_cache(struct page *page)
 399 {
 400 }
 401
 402 static inline void delete_from_swap_cache(struct page *page)
 403 {
 404 }
 405
 406 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 407
 408 static inline int try_to_free_swap(struct page *page)
 409 {
 410         return 0;
 411 }
 412
 413 static inline swp_entry_t get_swap_page(void)
 414 {
 415         swp_entry_t entry;
 416         entry.val = 0;
 417         return entry;
 418 }
 419
 420 /* linux/mm/thrash.c */
 421 #define put_swap_token(x) do { } while(0)
 422 #define grab_swap_token()  do { } while(0)
 423 #define has_swap_token(x) 0
 424 #define disable_swap_token() do { } while(0)
 425
 426 static inline int mem_cgroup_cache_charge_swapin(struct page *page,
 427                         struct mm_struct *mm, gfp_t mask, bool locked)
 428 {
 429         return 0;
 430 }
 431
 432 static inline void
 433 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 434 {
 435 }
 436
 437 #endif /* CONFIG_SWAP */
 438 #endif /* __KERNEL__*/
 439 #endif /* _LINUX_SWAP_H */