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/sched.h>
   9
  10 #include <asm/atomic.h>
  11 #include <asm/page.h>
  12
  13 struct notifier_block;
  14
  15 struct bio;
  16
  17 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  18 #define SWAP_FLAG_PRIO_MASK     0x7fff
  19 #define SWAP_FLAG_PRIO_SHIFT    0
  20
  21 static inline int current_is_kswapd(void)
  22 {
  23         return current->flags & PF_KSWAPD;
  24 }
  25
  26 /*
  27  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  28  * be swapped to.  The swap type and the offset into that swap type are
  29  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  30  * for the type means that the maximum number of swapcache pages is 27 bits
  31  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  32  * the type/offset into the pte as 5/27 as well.
  33  */
  34 #define MAX_SWAPFILES_SHIFT     5
  35 #ifndef CONFIG_MIGRATION
  36 #define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  37 #else
  38 /* Use last two entries for page migration swap entries */
  39 #define MAX_SWAPFILES           ((1 << MAX_SWAPFILES_SHIFT)-2)
  40 #define SWP_MIGRATION_READ      MAX_SWAPFILES
  41 #define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + 1)
  42 #endif
  43
  44 /*
  45  * Magic header for a swap area. The first part of the union is
  46  * what the swap magic looks like for the old (limited to 128MB)
  47  * swap area format, the second part of the union adds - in the
  48  * old reserved area - some extra information. Note that the first
  49  * kilobyte is reserved for boot loader or disk label stuff...
  50  *
  51  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  52  * areas somewhat tricky on machines that support multiple page sizes.
  53  * For 2.5 we'll probably want to move the magic to just beyond the
  54  * bootbits...
  55  */
  56 union swap_header {
  57         struct {
  58                 char reserved[PAGE_SIZE - 10];
  59                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  60         } magic;
  61         struct {
  62                 char            bootbits[1024]; /* Space for disklabel etc. */
  63                 __u32           version;
  64                 __u32           last_page;
  65                 __u32           nr_badpages;
  66                 unsigned char   sws_uuid[16];
  67                 unsigned char   sws_volume[16];
  68                 __u32           padding[117];
  69                 __u32           badpages[1];
  70         } info;
  71 };
  72
  73  /* A swap entry has to fit into a "unsigned long", as
  74   * the entry is hidden in the "index" field of the
  75   * swapper address space.
  76   */
  77 typedef struct {
  78         unsigned long val;
  79 } swp_entry_t;
  80
  81 /*
  82  * current->reclaim_state points to one of these when a task is running
  83  * memory reclaim
  84  */
  85 struct reclaim_state {
  86         unsigned long reclaimed_slab;
  87 };
  88
  89 #ifdef __KERNEL__
  90
  91 struct address_space;
  92 struct sysinfo;
  93 struct writeback_control;
  94 struct zone;
  95
  96 /*
  97  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
  98  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
  99  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 100  * from setup, they're handled identically.
 101  *
 102  * We always assume that blocks are of size PAGE_SIZE.
 103  */
 104 struct swap_extent {
 105         struct list_head list;
 106         pgoff_t start_page;
 107         pgoff_t nr_pages;
 108         sector_t start_block;
 109 };
 110
 111 /*
 112  * Max bad pages in the new format..
 113  */
 114 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 115 #define MAX_SWAP_BADPAGES \
 116         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 117
 118 enum {
 119         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 120         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 121         SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 122                                         /* add others here before... */
 123         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 124 };
 125
 126 #define SWAP_CLUSTER_MAX 32
 127
 128 #define SWAP_MAP_MAX    0x7fff
 129 #define SWAP_MAP_BAD    0x8000
 130
 131 /*
 132  * The in-memory structure used to track swap areas.
 133  */
 134 struct swap_info_struct {
 135         unsigned int flags;
 136         int prio;                       /* swap priority */
 137         struct file *swap_file;
 138         struct block_device *bdev;
 139         struct list_head extent_list;
 140         struct swap_extent *curr_swap_extent;
 141         unsigned old_block_size;
 142         unsigned short * swap_map;
 143         unsigned int lowest_bit;
 144         unsigned int highest_bit;
 145         unsigned int cluster_next;
 146         unsigned int cluster_nr;
 147         unsigned int pages;
 148         unsigned int max;
 149         unsigned int inuse_pages;
 150         int next;                       /* next entry on swap list */
 151 };
 152
 153 struct swap_list_t {
 154         int head;       /* head of priority-ordered swapfile list */
 155         int next;       /* swapfile to be used next */
 156 };
 157
 158 /* Swap 50% full? Release swapcache more aggressively.. */
 159 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 160
 161 /* linux/mm/oom_kill.c */
 162 extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, int order);
 163 extern int register_oom_notifier(struct notifier_block *nb);
 164 extern int unregister_oom_notifier(struct notifier_block *nb);
 165
 166 /* linux/mm/memory.c */
 167 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 168
 169 /* linux/mm/page_alloc.c */
 170 extern unsigned long totalram_pages;
 171 extern unsigned long totalreserve_pages;
 172 extern long nr_swap_pages;
 173 extern unsigned int nr_free_buffer_pages(void);
 174 extern unsigned int nr_free_pagecache_pages(void);
 175
 176 /* Definition of global_page_state not available yet */
 177 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
 178
 179
 180 /* linux/mm/swap.c */
 181 extern void FASTCALL(lru_cache_add(struct page *));
 182 extern void FASTCALL(lru_cache_add_active(struct page *));
 183 extern void FASTCALL(activate_page(struct page *));
 184 extern void FASTCALL(mark_page_accessed(struct page *));
 185 extern void lru_add_drain(void);
 186 extern int lru_add_drain_all(void);
 187 extern int rotate_reclaimable_page(struct page *page);
 188 extern void swap_setup(void);
 189
 190 /* linux/mm/vmscan.c */
 191 extern unsigned long try_to_free_pages(struct zone **zones, int order,
 192                                         gfp_t gfp_mask);
 193 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 194 extern int vm_swappiness;
 195 extern int remove_mapping(struct address_space *mapping, struct page *page);
 196 extern long vm_total_pages;
 197
 198 #ifdef CONFIG_NUMA
 199 extern int zone_reclaim_mode;
 200 extern int sysctl_min_unmapped_ratio;
 201 extern int sysctl_min_slab_ratio;
 202 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 203 #else
 204 #define zone_reclaim_mode 0
 205 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 206 {
 207         return 0;
 208 }
 209 #endif
 210
 211 extern int kswapd_run(int nid);
 212
 213 #ifdef CONFIG_MMU
 214 /* linux/mm/shmem.c */
 215 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 216 #endif /* CONFIG_MMU */
 217
 218 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 219
 220 #ifdef CONFIG_SWAP
 221 /* linux/mm/page_io.c */
 222 extern int swap_readpage(struct file *, struct page *);
 223 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 224 extern int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err);
 225
 226 /* linux/mm/swap_state.c */
 227 extern struct address_space swapper_space;
 228 #define total_swapcache_pages  swapper_space.nrpages
 229 extern void show_swap_cache_info(void);
 230 extern int add_to_swap(struct page *, gfp_t);
 231 extern void __delete_from_swap_cache(struct page *);
 232 extern void delete_from_swap_cache(struct page *);
 233 extern int move_to_swap_cache(struct page *, swp_entry_t);
 234 extern int move_from_swap_cache(struct page *, unsigned long,
 235                 struct address_space *);
 236 extern void free_page_and_swap_cache(struct page *);
 237 extern void free_pages_and_swap_cache(struct page **, int);
 238 extern struct page * lookup_swap_cache(swp_entry_t);
 239 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 240                                            unsigned long addr);
 241 /* linux/mm/swapfile.c */
 242 extern long total_swap_pages;
 243 extern unsigned int nr_swapfiles;
 244 extern void si_swapinfo(struct sysinfo *);
 245 extern swp_entry_t get_swap_page(void);
 246 extern swp_entry_t get_swap_page_of_type(int);
 247 extern int swap_duplicate(swp_entry_t);
 248 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 249 extern void swap_free(swp_entry_t);
 250 extern void free_swap_and_cache(swp_entry_t);
 251 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 252 extern unsigned int count_swap_pages(int, int);
 253 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 254 extern sector_t swapdev_block(int, pgoff_t);
 255 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 256 extern int can_share_swap_page(struct page *);
 257 extern int remove_exclusive_swap_page(struct page *);
 258 struct backing_dev_info;
 259
 260 extern spinlock_t swap_lock;
 261
 262 /* linux/mm/thrash.c */
 263 extern struct mm_struct * swap_token_mm;
 264 extern void grab_swap_token(void);
 265 extern void __put_swap_token(struct mm_struct *);
 266
 267 static inline int has_swap_token(struct mm_struct *mm)
 268 {
 269         return (mm == swap_token_mm);
 270 }
 271
 272 static inline void put_swap_token(struct mm_struct *mm)
 273 {
 274         if (has_swap_token(mm))
 275                 __put_swap_token(mm);
 276 }
 277
 278 static inline void disable_swap_token(void)
 279 {
 280         put_swap_token(swap_token_mm);
 281 }
 282
 283 #else /* CONFIG_SWAP */
 284
 285 #define total_swap_pages                        0
 286 #define total_swapcache_pages                   0UL
 287
 288 #define si_swapinfo(val) \
 289         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 290 /* only sparc can not include linux/pagemap.h in this file
 291  * so leave page_cache_release and release_pages undeclared... */
 292 #define free_page_and_swap_cache(page) \
 293         page_cache_release(page)
 294 #define free_pages_and_swap_cache(pages, nr) \
 295         release_pages((pages), (nr), 0);
 296
 297 static inline void show_swap_cache_info(void)
 298 {
 299 }
 300
 301 static inline void free_swap_and_cache(swp_entry_t swp)
 302 {
 303 }
 304
 305 static inline int swap_duplicate(swp_entry_t swp)
 306 {
 307         return 0;
 308 }
 309
 310 static inline void swap_free(swp_entry_t swp)
 311 {
 312 }
 313
 314 static inline struct page *read_swap_cache_async(swp_entry_t swp,
 315                         struct vm_area_struct *vma, unsigned long addr)
 316 {
 317         return NULL;
 318 }
 319
 320 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 321 {
 322         return NULL;
 323 }
 324
 325 static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
 326 {
 327         return 0;
 328 }
 329
 330 #define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 331
 332 static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
 333 {
 334         return 1;
 335 }
 336
 337 static inline int move_from_swap_cache(struct page *page, unsigned long index,
 338                                         struct address_space *mapping)
 339 {
 340         return 1;
 341 }
 342
 343 static inline void __delete_from_swap_cache(struct page *page)
 344 {
 345 }
 346
 347 static inline void delete_from_swap_cache(struct page *page)
 348 {
 349 }
 350
 351 #define swap_token_default_timeout              0
 352
 353 static inline int remove_exclusive_swap_page(struct page *p)
 354 {
 355         return 0;
 356 }
 357
 358 static inline swp_entry_t get_swap_page(void)
 359 {
 360         swp_entry_t entry;
 361         entry.val = 0;
 362         return entry;
 363 }
 364
 365 /* linux/mm/thrash.c */
 366 #define put_swap_token(x) do { } while(0)
 367 #define grab_swap_token()  do { } while(0)
 368 #define has_swap_token(x) 0
 369 #define disable_swap_token() do { } while(0)
 370
 371 #endif /* CONFIG_SWAP */
 372 #endif /* __KERNEL__*/
 373 #endif /* _LINUX_SWAP_H */