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    0x7fff
 133 #define SWAP_MAP_BAD    0x8000
 134
 135 /*
 136  * The in-memory structure used to track swap areas.
 137  */
 138 struct swap_info_struct {
 139         unsigned long flags;
 140         int prio;                       /* swap priority */
 141         int next;                       /* next entry on swap list */
 142         struct file *swap_file;
 143         struct block_device *bdev;
 144         struct list_head extent_list;
 145         struct swap_extent *curr_swap_extent;
 146         unsigned short *swap_map;
 147         unsigned int lowest_bit;
 148         unsigned int highest_bit;
 149         unsigned int lowest_alloc;      /* while preparing discard cluster */
 150         unsigned int highest_alloc;     /* while preparing discard cluster */
 151         unsigned int cluster_next;
 152         unsigned int cluster_nr;
 153         unsigned int pages;
 154         unsigned int max;
 155         unsigned int inuse_pages;
 156         unsigned int old_block_size;
 157 };
 158
 159 struct swap_list_t {
 160         int head;       /* head of priority-ordered swapfile list */
 161         int next;       /* swapfile to be used next */
 162 };
 163
 164 /* Swap 50% full? Release swapcache more aggressively.. */
 165 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 166
 167 /* linux/mm/page_alloc.c */
 168 extern unsigned long totalram_pages;
 169 extern unsigned long totalreserve_pages;
 170 extern unsigned int nr_free_buffer_pages(void);
 171 extern unsigned int nr_free_pagecache_pages(void);
 172
 173 /* Definition of global_page_state not available yet */
 174 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 175
 176
 177 /* linux/mm/swap.c */
 178 extern void __lru_cache_add(struct page *, enum lru_list lru);
 179 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 180 extern void activate_page(struct page *);
 181 extern void mark_page_accessed(struct page *);
 182 extern void lru_add_drain(void);
 183 extern int lru_add_drain_all(void);
 184 extern void rotate_reclaimable_page(struct page *page);
 185 extern void swap_setup(void);
 186
 187 extern void add_page_to_unevictable_list(struct page *page);
 188
 189 /**
 190  * lru_cache_add: add a page to the page lists
 191  * @page: the page to add
 192  */
 193 static inline void lru_cache_add_anon(struct page *page)
 194 {
 195         __lru_cache_add(page, LRU_INACTIVE_ANON);
 196 }
 197
 198 static inline void lru_cache_add_active_anon(struct page *page)
 199 {
 200         __lru_cache_add(page, LRU_ACTIVE_ANON);
 201 }
 202
 203 static inline void lru_cache_add_file(struct page *page)
 204 {
 205         __lru_cache_add(page, LRU_INACTIVE_FILE);
 206 }
 207
 208 static inline void lru_cache_add_active_file(struct page *page)
 209 {
 210         __lru_cache_add(page, LRU_ACTIVE_FILE);
 211 }
 212
 213 /* linux/mm/vmscan.c */
 214 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 215                                         gfp_t gfp_mask, nodemask_t *mask);
 216 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 217                                                   gfp_t gfp_mask, bool noswap,
 218                                                   unsigned int swappiness);
 219 extern int __isolate_lru_page(struct page *page, int mode, int file);
 220 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 221 extern int vm_swappiness;
 222 extern int remove_mapping(struct address_space *mapping, struct page *page);
 223 extern long vm_total_pages;
 224
 225 #ifdef CONFIG_NUMA
 226 extern int zone_reclaim_mode;
 227 extern int sysctl_min_unmapped_ratio;
 228 extern int sysctl_min_slab_ratio;
 229 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 230 #else
 231 #define zone_reclaim_mode 0
 232 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 233 {
 234         return 0;
 235 }
 236 #endif
 237
 238 #ifdef CONFIG_UNEVICTABLE_LRU
 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 #else
 248 static inline int page_evictable(struct page *page,
 249                                                 struct vm_area_struct *vma)
 250 {
 251         return 1;
 252 }
 253
 254 static inline void scan_mapping_unevictable_pages(struct address_space *mapping)
 255 {
 256 }
 257
 258 static inline int scan_unevictable_register_node(struct node *node)
 259 {
 260         return 0;
 261 }
 262
 263 static inline void scan_unevictable_unregister_node(struct node *node) { }
 264 #endif
 265
 266 extern int kswapd_run(int nid);
 267
 268 #ifdef CONFIG_MMU
 269 /* linux/mm/shmem.c */
 270 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 271 #endif /* CONFIG_MMU */
 272
 273 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 274
 275 #ifdef CONFIG_SWAP
 276 /* linux/mm/page_io.c */
 277 extern int swap_readpage(struct file *, struct page *);
 278 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 279 extern void end_swap_bio_read(struct bio *bio, int err);
 280
 281 /* linux/mm/swap_state.c */
 282 extern struct address_space swapper_space;
 283 #define total_swapcache_pages  swapper_space.nrpages
 284 extern void show_swap_cache_info(void);
 285 extern int add_to_swap(struct page *);
 286 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 287 extern void __delete_from_swap_cache(struct page *);
 288 extern void delete_from_swap_cache(struct page *);
 289 extern void free_page_and_swap_cache(struct page *);
 290 extern void free_pages_and_swap_cache(struct page **, int);
 291 extern struct page *lookup_swap_cache(swp_entry_t);
 292 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 293                         struct vm_area_struct *vma, unsigned long addr);
 294 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 295                         struct vm_area_struct *vma, unsigned long addr);
 296
 297 /* linux/mm/swapfile.c */
 298 extern long nr_swap_pages;
 299 extern long total_swap_pages;
 300 extern void si_swapinfo(struct sysinfo *);
 301 extern swp_entry_t get_swap_page(void);
 302 extern swp_entry_t get_swap_page_of_type(int);
 303 extern int swap_duplicate(swp_entry_t);
 304 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 305 extern void swap_free(swp_entry_t);
 306 extern int free_swap_and_cache(swp_entry_t);
 307 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 308 extern unsigned int count_swap_pages(int, int);
 309 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 310 extern sector_t swapdev_block(int, pgoff_t);
 311 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 312 extern int reuse_swap_page(struct page *);
 313 extern int try_to_free_swap(struct page *);
 314 struct backing_dev_info;
 315
 316 /* linux/mm/thrash.c */
 317 extern struct mm_struct * swap_token_mm;
 318 extern void grab_swap_token(void);
 319 extern void __put_swap_token(struct mm_struct *);
 320
 321 static inline int has_swap_token(struct mm_struct *mm)
 322 {
 323         return (mm == swap_token_mm);
 324 }
 325
 326 static inline void put_swap_token(struct mm_struct *mm)
 327 {
 328         if (has_swap_token(mm))
 329                 __put_swap_token(mm);
 330 }
 331
 332 static inline void disable_swap_token(void)
 333 {
 334         put_swap_token(swap_token_mm);
 335 }
 336
 337 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 338 extern void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent);
 339 #else
 340 static inline void
 341 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 342 {
 343 }
 344 #endif
 345 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 346 extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 347 #else
 348 static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 349 {
 350 }
 351 #endif
 352
 353 #else /* CONFIG_SWAP */
 354
 355 #define nr_swap_pages                           0L
 356 #define total_swap_pages                        0L
 357 #define total_swapcache_pages                   0UL
 358
 359 #define si_swapinfo(val) \
 360         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 361 /* only sparc can not include linux/pagemap.h in this file
 362  * so leave page_cache_release and release_pages undeclared... */
 363 #define free_page_and_swap_cache(page) \
 364         page_cache_release(page)
 365 #define free_pages_and_swap_cache(pages, nr) \
 366         release_pages((pages), (nr), 0);
 367
 368 static inline void show_swap_cache_info(void)
 369 {
 370 }
 371
 372 #define free_swap_and_cache(swp)        is_migration_entry(swp)
 373 #define swap_duplicate(swp)             is_migration_entry(swp)
 374
 375 static inline void swap_free(swp_entry_t swp)
 376 {
 377 }
 378
 379 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 380                         struct vm_area_struct *vma, unsigned long addr)
 381 {
 382         return NULL;
 383 }
 384
 385 static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 386 {
 387         return 0;
 388 }
 389
 390 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 391 {
 392         return NULL;
 393 }
 394
 395 static inline int add_to_swap(struct page *page)
 396 {
 397         return 0;
 398 }
 399
 400 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 401                                                         gfp_t gfp_mask)
 402 {
 403         return -1;
 404 }
 405
 406 static inline void __delete_from_swap_cache(struct page *page)
 407 {
 408 }
 409
 410 static inline void delete_from_swap_cache(struct page *page)
 411 {
 412 }
 413
 414 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 415
 416 static inline int try_to_free_swap(struct page *page)
 417 {
 418         return 0;
 419 }
 420
 421 static inline swp_entry_t get_swap_page(void)
 422 {
 423         swp_entry_t entry;
 424         entry.val = 0;
 425         return entry;
 426 }
 427
 428 /* linux/mm/thrash.c */
 429 #define put_swap_token(x) do { } while(0)
 430 #define grab_swap_token()  do { } while(0)
 431 #define has_swap_token(x) 0
 432 #define disable_swap_token() do { } while(0)
 433
 434 static inline int mem_cgroup_cache_charge_swapin(struct page *page,
 435                         struct mm_struct *mm, gfp_t mask, bool locked)
 436 {
 437         return 0;
 438 }
 439
 440 #endif /* CONFIG_SWAP */
 441 #endif /* __KERNEL__*/
 442 #endif /* _LINUX_SWAP_H */