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                                         /* add others here before... */
 125         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 126 };
 127
 128 #define SWAP_CLUSTER_MAX 32
 129
 130 #define SWAP_MAP_MAX    0x7fff
 131 #define SWAP_MAP_BAD    0x8000
 132
 133 /*
 134  * The in-memory structure used to track swap areas.
 135  */
 136 struct swap_info_struct {
 137         unsigned long flags;
 138         int prio;                       /* swap priority */
 139         int next;                       /* next entry on swap list */
 140         struct file *swap_file;
 141         struct block_device *bdev;
 142         struct list_head extent_list;
 143         struct swap_extent *curr_swap_extent;
 144         unsigned short *swap_map;
 145         unsigned int lowest_bit;
 146         unsigned int highest_bit;
 147         unsigned int cluster_next;
 148         unsigned int cluster_nr;
 149         unsigned int pages;
 150         unsigned int max;
 151         unsigned int inuse_pages;
 152         unsigned int old_block_size;
 153 };
 154
 155 struct swap_list_t {
 156         int head;       /* head of priority-ordered swapfile list */
 157         int next;       /* swapfile to be used next */
 158 };
 159
 160 /* Swap 50% full? Release swapcache more aggressively.. */
 161 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 162
 163 /* linux/mm/page_alloc.c */
 164 extern unsigned long totalram_pages;
 165 extern unsigned long totalreserve_pages;
 166 extern unsigned int nr_free_buffer_pages(void);
 167 extern unsigned int nr_free_pagecache_pages(void);
 168
 169 /* Definition of global_page_state not available yet */
 170 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 171
 172
 173 /* linux/mm/swap.c */
 174 extern void __lru_cache_add(struct page *, enum lru_list lru);
 175 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 176 extern void activate_page(struct page *);
 177 extern void mark_page_accessed(struct page *);
 178 extern void lru_add_drain(void);
 179 extern int lru_add_drain_all(void);
 180 extern void rotate_reclaimable_page(struct page *page);
 181 extern void swap_setup(void);
 182
 183 extern void add_page_to_unevictable_list(struct page *page);
 184
 185 /**
 186  * lru_cache_add: add a page to the page lists
 187  * @page: the page to add
 188  */
 189 static inline void lru_cache_add_anon(struct page *page)
 190 {
 191         __lru_cache_add(page, LRU_INACTIVE_ANON);
 192 }
 193
 194 static inline void lru_cache_add_active_anon(struct page *page)
 195 {
 196         __lru_cache_add(page, LRU_ACTIVE_ANON);
 197 }
 198
 199 static inline void lru_cache_add_file(struct page *page)
 200 {
 201         __lru_cache_add(page, LRU_INACTIVE_FILE);
 202 }
 203
 204 static inline void lru_cache_add_active_file(struct page *page)
 205 {
 206         __lru_cache_add(page, LRU_ACTIVE_FILE);
 207 }
 208
 209 /* linux/mm/vmscan.c */
 210 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 211                                         gfp_t gfp_mask);
 212 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 213                                                         gfp_t gfp_mask);
 214 extern int __isolate_lru_page(struct page *page, int mode, int file);
 215 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 216 extern int vm_swappiness;
 217 extern int remove_mapping(struct address_space *mapping, struct page *page);
 218 extern long vm_total_pages;
 219
 220 #ifdef CONFIG_NUMA
 221 extern int zone_reclaim_mode;
 222 extern int sysctl_min_unmapped_ratio;
 223 extern int sysctl_min_slab_ratio;
 224 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 225 #else
 226 #define zone_reclaim_mode 0
 227 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 228 {
 229         return 0;
 230 }
 231 #endif
 232
 233 #ifdef CONFIG_UNEVICTABLE_LRU
 234 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 235 extern void scan_mapping_unevictable_pages(struct address_space *);
 236
 237 extern unsigned long scan_unevictable_pages;
 238 extern int scan_unevictable_handler(struct ctl_table *, int, struct file *,
 239                                         void __user *, size_t *, loff_t *);
 240 extern int scan_unevictable_register_node(struct node *node);
 241 extern void scan_unevictable_unregister_node(struct node *node);
 242 #else
 243 static inline int page_evictable(struct page *page,
 244                                                 struct vm_area_struct *vma)
 245 {
 246         return 1;
 247 }
 248
 249 static inline void scan_mapping_unevictable_pages(struct address_space *mapping)
 250 {
 251 }
 252
 253 static inline int scan_unevictable_register_node(struct node *node)
 254 {
 255         return 0;
 256 }
 257
 258 static inline void scan_unevictable_unregister_node(struct node *node) { }
 259 #endif
 260
 261 extern int kswapd_run(int nid);
 262
 263 #ifdef CONFIG_MMU
 264 /* linux/mm/shmem.c */
 265 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 266 #endif /* CONFIG_MMU */
 267
 268 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 269
 270 #ifdef CONFIG_SWAP
 271 /* linux/mm/page_io.c */
 272 extern int swap_readpage(struct file *, struct page *);
 273 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 274 extern void end_swap_bio_read(struct bio *bio, int err);
 275
 276 /* linux/mm/swap_state.c */
 277 extern struct address_space swapper_space;
 278 #define total_swapcache_pages  swapper_space.nrpages
 279 extern void show_swap_cache_info(void);
 280 extern int add_to_swap(struct page *);
 281 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 282 extern void __delete_from_swap_cache(struct page *);
 283 extern void delete_from_swap_cache(struct page *);
 284 extern void free_page_and_swap_cache(struct page *);
 285 extern void free_pages_and_swap_cache(struct page **, int);
 286 extern struct page *lookup_swap_cache(swp_entry_t);
 287 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 288                         struct vm_area_struct *vma, unsigned long addr);
 289 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 290                         struct vm_area_struct *vma, unsigned long addr);
 291
 292 /* linux/mm/swapfile.c */
 293 extern long nr_swap_pages;
 294 extern long total_swap_pages;
 295 extern void si_swapinfo(struct sysinfo *);
 296 extern swp_entry_t get_swap_page(void);
 297 extern swp_entry_t get_swap_page_of_type(int);
 298 extern int swap_duplicate(swp_entry_t);
 299 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 300 extern void swap_free(swp_entry_t);
 301 extern void free_swap_and_cache(swp_entry_t);
 302 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 303 extern unsigned int count_swap_pages(int, int);
 304 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 305 extern sector_t swapdev_block(int, pgoff_t);
 306 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 307 extern int reuse_swap_page(struct page *);
 308 extern int try_to_free_swap(struct page *);
 309 struct backing_dev_info;
 310
 311 /* linux/mm/thrash.c */
 312 extern struct mm_struct * swap_token_mm;
 313 extern void grab_swap_token(void);
 314 extern void __put_swap_token(struct mm_struct *);
 315
 316 static inline int has_swap_token(struct mm_struct *mm)
 317 {
 318         return (mm == swap_token_mm);
 319 }
 320
 321 static inline void put_swap_token(struct mm_struct *mm)
 322 {
 323         if (has_swap_token(mm))
 324                 __put_swap_token(mm);
 325 }
 326
 327 static inline void disable_swap_token(void)
 328 {
 329         put_swap_token(swap_token_mm);
 330 }
 331
 332 #else /* CONFIG_SWAP */
 333
 334 #define nr_swap_pages                           0L
 335 #define total_swap_pages                        0L
 336 #define total_swapcache_pages                   0UL
 337
 338 #define si_swapinfo(val) \
 339         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 340 /* only sparc can not include linux/pagemap.h in this file
 341  * so leave page_cache_release and release_pages undeclared... */
 342 #define free_page_and_swap_cache(page) \
 343         page_cache_release(page)
 344 #define free_pages_and_swap_cache(pages, nr) \
 345         release_pages((pages), (nr), 0);
 346
 347 static inline void show_swap_cache_info(void)
 348 {
 349 }
 350
 351 static inline void free_swap_and_cache(swp_entry_t swp)
 352 {
 353 }
 354
 355 static inline int swap_duplicate(swp_entry_t swp)
 356 {
 357         return 0;
 358 }
 359
 360 static inline void swap_free(swp_entry_t swp)
 361 {
 362 }
 363
 364 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 365                         struct vm_area_struct *vma, unsigned long addr)
 366 {
 367         return NULL;
 368 }
 369
 370 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 371 {
 372         return NULL;
 373 }
 374
 375 static inline int add_to_swap(struct page *page)
 376 {
 377         return 0;
 378 }
 379
 380 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 381                                                         gfp_t gfp_mask)
 382 {
 383         return -1;
 384 }
 385
 386 static inline void __delete_from_swap_cache(struct page *page)
 387 {
 388 }
 389
 390 static inline void delete_from_swap_cache(struct page *page)
 391 {
 392 }
 393
 394 #define reuse_swap_page(page)   (page_mapcount(page) == 1)
 395
 396 static inline int try_to_free_swap(struct page *page)
 397 {
 398         return 0;
 399 }
 400
 401 static inline swp_entry_t get_swap_page(void)
 402 {
 403         swp_entry_t entry;
 404         entry.val = 0;
 405         return entry;
 406 }
 407
 408 /* linux/mm/thrash.c */
 409 #define put_swap_token(x) do { } while(0)
 410 #define grab_swap_token()  do { } while(0)
 411 #define has_swap_token(x) 0
 412 #define disable_swap_token() do { } while(0)
 413
 414 #endif /* CONFIG_SWAP */
 415 #endif /* __KERNEL__*/
 416 #endif /* _LINUX_SWAP_H */