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/memcontrol.h>
   9#include <linux/sched.h>
  10#include <linux/node.h>
  11
  12#include <asm/atomic.h>
  13#include <asm/page.h>
  14
  15struct notifier_block;
  16
  17struct bio;
  18
  19#define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  20#define SWAP_FLAG_PRIO_MASK     0x7fff
  21#define SWAP_FLAG_PRIO_SHIFT    0
  22
  23static inline int current_is_kswapd(void)
  24{
  25        return current->flags & PF_KSWAPD;
  26}
  27
  28/*
  29 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  30 * be swapped to.  The swap type and the offset into that swap type are
  31 * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  32 * for the type means that the maximum number of swapcache pages is 27 bits
  33 * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  34 * the type/offset into the pte as 5/27 as well.
  35 */
  36#define MAX_SWAPFILES_SHIFT     5
  37#ifndef CONFIG_MIGRATION
  38#define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  39#else
  40/* Use last two entries for page migration swap entries */
  41#define MAX_SWAPFILES           ((1 << MAX_SWAPFILES_SHIFT)-2)
  42#define SWP_MIGRATION_READ      MAX_SWAPFILES
  43#define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + 1)
  44#endif
  45
  46/*
  47 * Magic header for a swap area. The first part of the union is
  48 * what the swap magic looks like for the old (limited to 128MB)
  49 * swap area format, the second part of the union adds - in the
  50 * old reserved area - some extra information. Note that the first
  51 * kilobyte is reserved for boot loader or disk label stuff...
  52 *
  53 * Having the magic at the end of the PAGE_SIZE makes detecting swap
  54 * areas somewhat tricky on machines that support multiple page sizes.
  55 * For 2.5 we'll probably want to move the magic to just beyond the
  56 * bootbits...
  57 */
  58union swap_header {
  59        struct {
  60                char reserved[PAGE_SIZE - 10];
  61                char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  62        } magic;
  63        struct {
  64                char            bootbits[1024]; /* Space for disklabel etc. */
  65                __u32           version;
  66                __u32           last_page;
  67                __u32           nr_badpages;
  68                unsigned char   sws_uuid[16];
  69                unsigned char   sws_volume[16];
  70                __u32           padding[117];
  71                __u32           badpages[1];
  72        } info;
  73};
  74
  75 /* A swap entry has to fit into a "unsigned long", as
  76  * the entry is hidden in the "index" field of the
  77  * swapper address space.
  78  */
  79typedef struct {
  80        unsigned long val;
  81} swp_entry_t;
  82
  83/*
  84 * current->reclaim_state points to one of these when a task is running
  85 * memory reclaim
  86 */
  87struct reclaim_state {
  88        unsigned long reclaimed_slab;
  89};
  90
  91#ifdef __KERNEL__
  92
  93struct address_space;
  94struct sysinfo;
  95struct writeback_control;
  96struct zone;
  97
  98/*
  99 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
 100 * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
 101 * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
 102 * from setup, they're handled identically.
 103 *
 104 * We always assume that blocks are of size PAGE_SIZE.
 105 */
 106struct swap_extent {
 107        struct list_head list;
 108        pgoff_t start_page;
 109        pgoff_t nr_pages;
 110        sector_t start_block;
 111};
 112
 113/*
 114 * Max bad pages in the new format..
 115 */
 116#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 117#define MAX_SWAP_BADPAGES \
 118        ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 119
 120enum {
 121        SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 122        SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 123        SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 124                                        /* add others here before... */
 125        SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 126};
 127
 128#define SWAP_CLUSTER_MAX 32
 129
 130#define SWAP_MAP_MAX    0x7fff
 131#define SWAP_MAP_BAD    0x8000
 132
 133/*
 134 * The in-memory structure used to track swap areas.
 135 */
 136struct swap_info_struct {
 137        unsigned int flags;
 138        int prio;                       /* swap priority */
 139        struct file *swap_file;
 140        struct block_device *bdev;
 141        struct list_head extent_list;
 142        struct swap_extent *curr_swap_extent;
 143        unsigned old_block_size;
 144        unsigned short * swap_map;
 145        unsigned int lowest_bit;
 146        unsigned int highest_bit;
 147        unsigned int cluster_next;
 148        unsigned int cluster_nr;
 149        unsigned int pages;
 150        unsigned int max;
 151        unsigned int inuse_pages;
 152        int next;                       /* next entry on swap list */
 153};
 154
 155struct swap_list_t {
 156        int head;       /* head of priority-ordered swapfile list */
 157        int next;       /* swapfile to be used next */
 158};
 159
 160/* Swap 50% full? Release swapcache more aggressively.. */
 161#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 162
 163/* linux/mm/page_alloc.c */
 164extern unsigned long totalram_pages;
 165extern unsigned long totalreserve_pages;
 166extern long nr_swap_pages;
 167extern unsigned int nr_free_buffer_pages(void);
 168extern unsigned int nr_free_pagecache_pages(void);
 169
 170/* Definition of global_page_state not available yet */
 171#define nr_free_pages() global_page_state(NR_FREE_PAGES)
 172
 173
 174/* linux/mm/swap.c */
 175extern void __lru_cache_add(struct page *, enum lru_list lru);
 176extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 177extern void lru_cache_add_active_or_unevictable(struct page *,
 178                                        struct vm_area_struct *);
 179extern void activate_page(struct page *);
 180extern void mark_page_accessed(struct page *);
 181extern void lru_add_drain(void);
 182extern int lru_add_drain_all(void);
 183extern void rotate_reclaimable_page(struct page *page);
 184extern void swap_setup(void);
 185
 186extern void add_page_to_unevictable_list(struct page *page);
 187
 188/**
 189 * lru_cache_add: add a page to the page lists
 190 * @page: the page to add
 191 */
 192static inline void lru_cache_add_anon(struct page *page)
 193{
 194        __lru_cache_add(page, LRU_INACTIVE_ANON);
 195}
 196
 197static inline void lru_cache_add_active_anon(struct page *page)
 198{
 199        __lru_cache_add(page, LRU_ACTIVE_ANON);
 200}
 201
 202static inline void lru_cache_add_file(struct page *page)
 203{
 204        __lru_cache_add(page, LRU_INACTIVE_FILE);
 205}
 206
 207static inline void lru_cache_add_active_file(struct page *page)
 208{
 209        __lru_cache_add(page, LRU_ACTIVE_FILE);
 210}
 211
 212/* linux/mm/vmscan.c */
 213extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 214                                        gfp_t gfp_mask);
 215extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 216                                                        gfp_t gfp_mask);
 217extern int __isolate_lru_page(struct page *page, int mode, int file);
 218extern unsigned long shrink_all_memory(unsigned long nr_pages);
 219extern int vm_swappiness;
 220extern int remove_mapping(struct address_space *mapping, struct page *page);
 221extern long vm_total_pages;
 222
 223#ifdef CONFIG_NUMA
 224extern int zone_reclaim_mode;
 225extern int sysctl_min_unmapped_ratio;
 226extern int sysctl_min_slab_ratio;
 227extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 228#else
 229#define zone_reclaim_mode 0
 230static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 231{
 232        return 0;
 233}
 234#endif
 235
 236#ifdef CONFIG_UNEVICTABLE_LRU
 237extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 238extern void scan_mapping_unevictable_pages(struct address_space *);
 239
 240extern unsigned long scan_unevictable_pages;
 241extern int scan_unevictable_handler(struct ctl_table *, int, struct file *,
 242                                        void __user *, size_t *, loff_t *);
 243extern int scan_unevictable_register_node(struct node *node);
 244extern void scan_unevictable_unregister_node(struct node *node);
 245#else
 246static inline int page_evictable(struct page *page,
 247                                                struct vm_area_struct *vma)
 248{
 249        return 1;
 250}
 251
 252static inline void scan_mapping_unevictable_pages(struct address_space *mapping)
 253{
 254}
 255
 256static inline int scan_unevictable_register_node(struct node *node)
 257{
 258        return 0;
 259}
 260
 261static inline void scan_unevictable_unregister_node(struct node *node) { }
 262#endif
 263
 264extern int kswapd_run(int nid);
 265
 266#ifdef CONFIG_MMU
 267/* linux/mm/shmem.c */
 268extern int shmem_unuse(swp_entry_t entry, struct page *page);
 269#endif /* CONFIG_MMU */
 270
 271extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 272
 273#ifdef CONFIG_SWAP
 274/* linux/mm/page_io.c */
 275extern int swap_readpage(struct file *, struct page *);
 276extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 277extern void end_swap_bio_read(struct bio *bio, int err);
 278
 279/* linux/mm/swap_state.c */
 280extern struct address_space swapper_space;
 281#define total_swapcache_pages  swapper_space.nrpages
 282extern void show_swap_cache_info(void);
 283extern int add_to_swap(struct page *, gfp_t);
 284extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 285extern void __delete_from_swap_cache(struct page *);
 286extern void delete_from_swap_cache(struct page *);
 287extern void free_page_and_swap_cache(struct page *);
 288extern void free_pages_and_swap_cache(struct page **, int);
 289extern struct page *lookup_swap_cache(swp_entry_t);
 290extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 291                        struct vm_area_struct *vma, unsigned long addr);
 292extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 293                        struct vm_area_struct *vma, unsigned long addr);
 294
 295/* linux/mm/swapfile.c */
 296extern long total_swap_pages;
 297extern void si_swapinfo(struct sysinfo *);
 298extern swp_entry_t get_swap_page(void);
 299extern swp_entry_t get_swap_page_of_type(int);
 300extern int swap_duplicate(swp_entry_t);
 301extern int valid_swaphandles(swp_entry_t, unsigned long *);
 302extern void swap_free(swp_entry_t);
 303extern void free_swap_and_cache(swp_entry_t);
 304extern int swap_type_of(dev_t, sector_t, struct block_device **);
 305extern unsigned int count_swap_pages(int, int);
 306extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 307extern sector_t swapdev_block(int, pgoff_t);
 308extern struct swap_info_struct *get_swap_info_struct(unsigned);
 309extern int can_share_swap_page(struct page *);
 310extern int remove_exclusive_swap_page(struct page *);
 311extern int remove_exclusive_swap_page_ref(struct page *);
 312struct backing_dev_info;
 313
 314/* linux/mm/thrash.c */
 315extern struct mm_struct * swap_token_mm;
 316extern void grab_swap_token(void);
 317extern void __put_swap_token(struct mm_struct *);
 318
 319static inline int has_swap_token(struct mm_struct *mm)
 320{
 321        return (mm == swap_token_mm);
 322}
 323
 324static inline void put_swap_token(struct mm_struct *mm)
 325{
 326        if (has_swap_token(mm))
 327                __put_swap_token(mm);
 328}
 329
 330static inline void disable_swap_token(void)
 331{
 332        put_swap_token(swap_token_mm);
 333}
 334
 335#else /* CONFIG_SWAP */
 336
 337#define total_swap_pages                        0
 338#define total_swapcache_pages                   0UL
 339
 340#define si_swapinfo(val) \
 341        do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 342/* only sparc can not include linux/pagemap.h in this file
 343 * so leave page_cache_release and release_pages undeclared... */
 344#define free_page_and_swap_cache(page) \
 345        page_cache_release(page)
 346#define free_pages_and_swap_cache(pages, nr) \
 347        release_pages((pages), (nr), 0);
 348
 349static inline void show_swap_cache_info(void)
 350{
 351}
 352
 353static inline void free_swap_and_cache(swp_entry_t swp)
 354{
 355}
 356
 357static inline int swap_duplicate(swp_entry_t swp)
 358{
 359        return 0;
 360}
 361
 362static inline void swap_free(swp_entry_t swp)
 363{
 364}
 365
 366static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 367                        struct vm_area_struct *vma, unsigned long addr)
 368{
 369        return NULL;
 370}
 371
 372static inline struct page *lookup_swap_cache(swp_entry_t swp)
 373{
 374        return NULL;
 375}
 376
 377#define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 378
 379static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 380                                                        gfp_t gfp_mask)
 381{
 382        return -1;
 383}
 384
 385static inline void __delete_from_swap_cache(struct page *page)
 386{
 387}
 388
 389static inline void delete_from_swap_cache(struct page *page)
 390{
 391}
 392
 393#define swap_token_default_timeout              0
 394
 395static inline int remove_exclusive_swap_page(struct page *p)
 396{
 397        return 0;
 398}
 399
 400static inline int remove_exclusive_swap_page_ref(struct page *page)
 401{
 402        return 0;
 403}
 404
 405static inline swp_entry_t get_swap_page(void)
 406{
 407        swp_entry_t entry;
 408        entry.val = 0;
 409        return entry;
 410}
 411
 412/* linux/mm/thrash.c */
 413#define put_swap_token(x) do { } while(0)
 414#define grab_swap_token()  do { } while(0)
 415#define has_swap_token(x) 0
 416#define disable_swap_token() do { } while(0)
 417
 418#endif /* CONFIG_SWAP */
 419#endif /* __KERNEL__*/
 420#endif /* _LINUX_SWAP_H */
 421