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