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