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