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_pages(void);
 174 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
 175 extern unsigned int nr_free_buffer_pages(void);
 176 extern unsigned int nr_free_pagecache_pages(void);
 177
 178 /* linux/mm/swap.c */
 179 extern void FASTCALL(lru_cache_add(struct page *));
 180 extern void FASTCALL(lru_cache_add_active(struct page *));
 181 extern void FASTCALL(activate_page(struct page *));
 182 extern void FASTCALL(mark_page_accessed(struct page *));
 183 extern void lru_add_drain(void);
 184 extern int lru_add_drain_all(void);
 185 extern int rotate_reclaimable_page(struct page *page);
 186 extern void swap_setup(void);
 187
 188 /* linux/mm/vmscan.c */
 189 extern unsigned long try_to_free_pages(struct zone **, gfp_t);
 190 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 191 extern int vm_swappiness;
 192 extern int remove_mapping(struct address_space *mapping, struct page *page);
 193 extern long vm_total_pages;
 194
 195 #ifdef CONFIG_NUMA
 196 extern int zone_reclaim_mode;
 197 extern int sysctl_min_unmapped_ratio;
 198 extern int sysctl_min_slab_ratio;
 199 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 200 #else
 201 #define zone_reclaim_mode 0
 202 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 203 {
 204         return 0;
 205 }
 206 #endif
 207
 208 extern int kswapd_run(int nid);
 209
 210 #ifdef CONFIG_MMU
 211 /* linux/mm/shmem.c */
 212 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 213 #endif /* CONFIG_MMU */
 214
 215 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 216
 217 #ifdef CONFIG_SWAP
 218 /* linux/mm/page_io.c */
 219 extern int swap_readpage(struct file *, struct page *);
 220 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 221 extern int end_swap_bio_read(struct bio *bio, unsigned int bytes_done, int err);
 222
 223 /* linux/mm/swap_state.c */
 224 extern struct address_space swapper_space;
 225 #define total_swapcache_pages  swapper_space.nrpages
 226 extern void show_swap_cache_info(void);
 227 extern int add_to_swap(struct page *, gfp_t);
 228 extern void __delete_from_swap_cache(struct page *);
 229 extern void delete_from_swap_cache(struct page *);
 230 extern int move_to_swap_cache(struct page *, swp_entry_t);
 231 extern int move_from_swap_cache(struct page *, unsigned long,
 232                 struct address_space *);
 233 extern void free_page_and_swap_cache(struct page *);
 234 extern void free_pages_and_swap_cache(struct page **, int);
 235 extern struct page * lookup_swap_cache(swp_entry_t);
 236 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 237                                            unsigned long addr);
 238 /* linux/mm/swapfile.c */
 239 extern long total_swap_pages;
 240 extern unsigned int nr_swapfiles;
 241 extern void si_swapinfo(struct sysinfo *);
 242 extern swp_entry_t get_swap_page(void);
 243 extern swp_entry_t get_swap_page_of_type(int);
 244 extern int swap_duplicate(swp_entry_t);
 245 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 246 extern void swap_free(swp_entry_t);
 247 extern void free_swap_and_cache(swp_entry_t);
 248 extern int swap_type_of(dev_t, sector_t);
 249 extern unsigned int count_swap_pages(int, int);
 250 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 251 extern sector_t swapdev_block(int, pgoff_t);
 252 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 253 extern int can_share_swap_page(struct page *);
 254 extern int remove_exclusive_swap_page(struct page *);
 255 struct backing_dev_info;
 256
 257 extern spinlock_t swap_lock;
 258
 259 /* linux/mm/thrash.c */
 260 extern struct mm_struct * swap_token_mm;
 261 extern void grab_swap_token(void);
 262 extern void __put_swap_token(struct mm_struct *);
 263
 264 static inline int has_swap_token(struct mm_struct *mm)
 265 {
 266         return (mm == swap_token_mm);
 267 }
 268
 269 static inline void put_swap_token(struct mm_struct *mm)
 270 {
 271         if (has_swap_token(mm))
 272                 __put_swap_token(mm);
 273 }
 274
 275 static inline void disable_swap_token(void)
 276 {
 277         put_swap_token(swap_token_mm);
 278 }
 279
 280 #else /* CONFIG_SWAP */
 281
 282 #define total_swap_pages                        0
 283 #define total_swapcache_pages                   0UL
 284
 285 #define si_swapinfo(val) \
 286         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 287 /* only sparc can not include linux/pagemap.h in this file
 288  * so leave page_cache_release and release_pages undeclared... */
 289 #define free_page_and_swap_cache(page) \
 290         page_cache_release(page)
 291 #define free_pages_and_swap_cache(pages, nr) \
 292         release_pages((pages), (nr), 0);
 293
 294 static inline void show_swap_cache_info(void)
 295 {
 296 }
 297
 298 static inline void free_swap_and_cache(swp_entry_t swp)
 299 {
 300 }
 301
 302 static inline int swap_duplicate(swp_entry_t swp)
 303 {
 304         return 0;
 305 }
 306
 307 static inline void swap_free(swp_entry_t swp)
 308 {
 309 }
 310
 311 static inline struct page *read_swap_cache_async(swp_entry_t swp,
 312                         struct vm_area_struct *vma, unsigned long addr)
 313 {
 314         return NULL;
 315 }
 316
 317 static inline struct page *lookup_swap_cache(swp_entry_t swp)
 318 {
 319         return NULL;
 320 }
 321
 322 static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
 323 {
 324         return 0;
 325 }
 326
 327 #define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 328
 329 static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
 330 {
 331         return 1;
 332 }
 333
 334 static inline int move_from_swap_cache(struct page *page, unsigned long index,
 335                                         struct address_space *mapping)
 336 {
 337         return 1;
 338 }
 339
 340 static inline void __delete_from_swap_cache(struct page *page)
 341 {
 342 }
 343
 344 static inline void delete_from_swap_cache(struct page *page)
 345 {
 346 }
 347
 348 #define swap_token_default_timeout              0
 349
 350 static inline int remove_exclusive_swap_page(struct page *p)
 351 {
 352         return 0;
 353 }
 354
 355 static inline swp_entry_t get_swap_page(void)
 356 {
 357         swp_entry_t entry;
 358         entry.val = 0;
 359         return entry;
 360 }
 361
 362 /* linux/mm/thrash.c */
 363 #define put_swap_token(x) do { } while(0)
 364 #define grab_swap_token()  do { } while(0)
 365 #define has_swap_token(x) 0
 366 #define disable_swap_token() do { } while(0)
 367
 368 #endif /* CONFIG_SWAP */
 369 #endif /* __KERNEL__*/
 370 #endif /* _LINUX_SWAP_H */