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
  13struct notifier_block;
  14
  15struct 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
  21static 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 */
  56union 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  */
  77typedef 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 */
  85struct reclaim_state {
  86        unsigned long reclaimed_slab;
  87};
  88
  89#ifdef __KERNEL__
  90
  91struct address_space;
  92struct sysinfo;
  93struct writeback_control;
  94struct 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 */
 104struct 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
 118enum {
 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 */
 134struct 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
 153struct 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/memory.c */
 162extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 163
 164/* linux/mm/page_alloc.c */
 165extern unsigned long totalram_pages;
 166extern unsigned long totalreserve_pages;
 167extern long nr_swap_pages;
 168extern unsigned int nr_free_buffer_pages(void);
 169extern unsigned int nr_free_pagecache_pages(void);
 170
 171/* Definition of global_page_state not available yet */
 172#define nr_free_pages() global_page_state(NR_FREE_PAGES)
 173
 174
 175/* linux/mm/swap.c */
 176extern void FASTCALL(lru_cache_add(struct page *));
 177extern void FASTCALL(lru_cache_add_active(struct page *));
 178extern void FASTCALL(activate_page(struct page *));
 179extern void FASTCALL(mark_page_accessed(struct page *));
 180extern void lru_add_drain(void);
 181extern int lru_add_drain_all(void);
 182extern int rotate_reclaimable_page(struct page *page);
 183extern void swap_setup(void);
 184
 185/* linux/mm/vmscan.c */
 186extern unsigned long try_to_free_pages(struct zone **zones, int order,
 187                                        gfp_t gfp_mask);
 188extern unsigned long shrink_all_memory(unsigned long nr_pages);
 189extern int vm_swappiness;
 190extern int remove_mapping(struct address_space *mapping, struct page *page);
 191extern long vm_total_pages;
 192
 193#ifdef CONFIG_NUMA
 194extern int zone_reclaim_mode;
 195extern int sysctl_min_unmapped_ratio;
 196extern int sysctl_min_slab_ratio;
 197extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 198#else
 199#define zone_reclaim_mode 0
 200static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 201{
 202        return 0;
 203}
 204#endif
 205
 206extern int kswapd_run(int nid);
 207
 208#ifdef CONFIG_MMU
 209/* linux/mm/shmem.c */
 210extern int shmem_unuse(swp_entry_t entry, struct page *page);
 211#endif /* CONFIG_MMU */
 212
 213extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 214
 215#ifdef CONFIG_SWAP
 216/* linux/mm/page_io.c */
 217extern int swap_readpage(struct file *, struct page *);
 218extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 219extern void end_swap_bio_read(struct bio *bio, int err);
 220
 221/* linux/mm/swap_state.c */
 222extern struct address_space swapper_space;
 223#define total_swapcache_pages  swapper_space.nrpages
 224extern void show_swap_cache_info(void);
 225extern int add_to_swap(struct page *, gfp_t);
 226extern void __delete_from_swap_cache(struct page *);
 227extern void delete_from_swap_cache(struct page *);
 228extern int move_to_swap_cache(struct page *, swp_entry_t);
 229extern int move_from_swap_cache(struct page *, unsigned long,
 230                struct address_space *);
 231extern void free_page_and_swap_cache(struct page *);
 232extern void free_pages_and_swap_cache(struct page **, int);
 233extern struct page * lookup_swap_cache(swp_entry_t);
 234extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 235                                           unsigned long addr);
 236/* linux/mm/swapfile.c */
 237extern long total_swap_pages;
 238extern unsigned int nr_swapfiles;
 239extern void si_swapinfo(struct sysinfo *);
 240extern swp_entry_t get_swap_page(void);
 241extern swp_entry_t get_swap_page_of_type(int);
 242extern int swap_duplicate(swp_entry_t);
 243extern int valid_swaphandles(swp_entry_t, unsigned long *);
 244extern void swap_free(swp_entry_t);
 245extern void free_swap_and_cache(swp_entry_t);
 246extern int swap_type_of(dev_t, sector_t, struct block_device **);
 247extern unsigned int count_swap_pages(int, int);
 248extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 249extern sector_t swapdev_block(int, pgoff_t);
 250extern struct swap_info_struct *get_swap_info_struct(unsigned);
 251extern int can_share_swap_page(struct page *);
 252extern int remove_exclusive_swap_page(struct page *);
 253struct backing_dev_info;
 254
 255extern spinlock_t swap_lock;
 256
 257/* linux/mm/thrash.c */
 258extern struct mm_struct * swap_token_mm;
 259extern void grab_swap_token(void);
 260extern void __put_swap_token(struct mm_struct *);
 261
 262static inline int has_swap_token(struct mm_struct *mm)
 263{
 264        return (mm == swap_token_mm);
 265}
 266
 267static inline void put_swap_token(struct mm_struct *mm)
 268{
 269        if (has_swap_token(mm))
 270                __put_swap_token(mm);
 271}
 272
 273static inline void disable_swap_token(void)
 274{
 275        put_swap_token(swap_token_mm);
 276}
 277
 278#else /* CONFIG_SWAP */
 279
 280#define total_swap_pages                        0
 281#define total_swapcache_pages                   0UL
 282
 283#define si_swapinfo(val) \
 284        do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 285/* only sparc can not include linux/pagemap.h in this file
 286 * so leave page_cache_release and release_pages undeclared... */
 287#define free_page_and_swap_cache(page) \
 288        page_cache_release(page)
 289#define free_pages_and_swap_cache(pages, nr) \
 290        release_pages((pages), (nr), 0);
 291
 292static inline void show_swap_cache_info(void)
 293{
 294}
 295
 296static inline void free_swap_and_cache(swp_entry_t swp)
 297{
 298}
 299
 300static inline int swap_duplicate(swp_entry_t swp)
 301{
 302        return 0;
 303}
 304
 305static inline void swap_free(swp_entry_t swp)
 306{
 307}
 308
 309static inline struct page *read_swap_cache_async(swp_entry_t swp,
 310                        struct vm_area_struct *vma, unsigned long addr)
 311{
 312        return NULL;
 313}
 314
 315static inline struct page *lookup_swap_cache(swp_entry_t swp)
 316{
 317        return NULL;
 318}
 319
 320static inline int valid_swaphandles(swp_entry_t entry, unsigned long *offset)
 321{
 322        return 0;
 323}
 324
 325#define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 326
 327static inline int move_to_swap_cache(struct page *page, swp_entry_t entry)
 328{
 329        return 1;
 330}
 331
 332static inline int move_from_swap_cache(struct page *page, unsigned long index,
 333                                        struct address_space *mapping)
 334{
 335        return 1;
 336}
 337
 338static inline void __delete_from_swap_cache(struct page *page)
 339{
 340}
 341
 342static inline void delete_from_swap_cache(struct page *page)
 343{
 344}
 345
 346#define swap_token_default_timeout              0
 347
 348static inline int remove_exclusive_swap_page(struct page *p)
 349{
 350        return 0;
 351}
 352
 353static inline swp_entry_t get_swap_page(void)
 354{
 355        swp_entry_t entry;
 356        entry.val = 0;
 357        return entry;
 358}
 359
 360/* linux/mm/thrash.c */
 361#define put_swap_token(x) do { } while(0)
 362#define grab_swap_token()  do { } while(0)
 363#define has_swap_token(x) 0
 364#define disable_swap_token() do { } while(0)
 365
 366#endif /* CONFIG_SWAP */
 367#endif /* __KERNEL__*/
 368#endif /* _LINUX_SWAP_H */
 369