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_DISCARDABLE = (1 << 2),     /* blkdev supports discard */
 124        SWP_DISCARDING  = (1 << 3),     /* now discarding a free cluster */
 125        SWP_SOLIDSTATE  = (1 << 4),     /* blkdev seeks are cheap */
 126                                        /* add others here before... */
 127        SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 128};
 129
 130#define SWAP_CLUSTER_MAX 32
 131
 132#define SWAP_MAP_MAX    0x7ffe
 133#define SWAP_MAP_BAD    0x7fff
 134#define SWAP_HAS_CACHE  0x8000          /* There is a swap cache of entry. */
 135#define SWAP_COUNT_MASK (~SWAP_HAS_CACHE)
 136/*
 137 * The in-memory structure used to track swap areas.
 138 */
 139struct swap_info_struct {
 140        unsigned long flags;
 141        int prio;                       /* swap priority */
 142        int next;                       /* next entry on swap list */
 143        struct file *swap_file;
 144        struct block_device *bdev;
 145        struct list_head extent_list;
 146        struct swap_extent *curr_swap_extent;
 147        unsigned short *swap_map;
 148        unsigned int lowest_bit;
 149        unsigned int highest_bit;
 150        unsigned int lowest_alloc;      /* while preparing discard cluster */
 151        unsigned int highest_alloc;     /* while preparing discard cluster */
 152        unsigned int cluster_next;
 153        unsigned int cluster_nr;
 154        unsigned int pages;
 155        unsigned int max;
 156        unsigned int inuse_pages;
 157        unsigned int old_block_size;
 158};
 159
 160struct swap_list_t {
 161        int head;       /* head of priority-ordered swapfile list */
 162        int next;       /* swapfile to be used next */
 163};
 164
 165/* Swap 50% full? Release swapcache more aggressively.. */
 166#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 167
 168/* linux/mm/page_alloc.c */
 169extern unsigned long totalram_pages;
 170extern unsigned long totalreserve_pages;
 171extern unsigned int nr_free_buffer_pages(void);
 172extern unsigned int nr_free_pagecache_pages(void);
 173
 174/* Definition of global_page_state not available yet */
 175#define nr_free_pages() global_page_state(NR_FREE_PAGES)
 176
 177
 178/* linux/mm/swap.c */
 179extern void __lru_cache_add(struct page *, enum lru_list lru);
 180extern void lru_cache_add_lru(struct page *, enum lru_list lru);
 181extern void activate_page(struct page *);
 182extern void mark_page_accessed(struct page *);
 183extern void lru_add_drain(void);
 184extern int lru_add_drain_all(void);
 185extern void rotate_reclaimable_page(struct page *page);
 186extern void swap_setup(void);
 187
 188extern void add_page_to_unevictable_list(struct page *page);
 189
 190/**
 191 * lru_cache_add: add a page to the page lists
 192 * @page: the page to add
 193 */
 194static inline void lru_cache_add_anon(struct page *page)
 195{
 196        __lru_cache_add(page, LRU_INACTIVE_ANON);
 197}
 198
 199static inline void lru_cache_add_active_anon(struct page *page)
 200{
 201        __lru_cache_add(page, LRU_ACTIVE_ANON);
 202}
 203
 204static inline void lru_cache_add_file(struct page *page)
 205{
 206        __lru_cache_add(page, LRU_INACTIVE_FILE);
 207}
 208
 209static inline void lru_cache_add_active_file(struct page *page)
 210{
 211        __lru_cache_add(page, LRU_ACTIVE_FILE);
 212}
 213
 214/* linux/mm/vmscan.c */
 215extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 216                                        gfp_t gfp_mask, nodemask_t *mask);
 217extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 218                                                  gfp_t gfp_mask, bool noswap,
 219                                                  unsigned int swappiness);
 220extern int __isolate_lru_page(struct page *page, int mode, int file);
 221extern unsigned long shrink_all_memory(unsigned long nr_pages);
 222extern int vm_swappiness;
 223extern int remove_mapping(struct address_space *mapping, struct page *page);
 224extern long vm_total_pages;
 225
 226#ifdef CONFIG_NUMA
 227extern int zone_reclaim_mode;
 228extern int sysctl_min_unmapped_ratio;
 229extern int sysctl_min_slab_ratio;
 230extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 231#else
 232#define zone_reclaim_mode 0
 233static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 234{
 235        return 0;
 236}
 237#endif
 238
 239extern int page_evictable(struct page *page, struct vm_area_struct *vma);
 240extern void scan_mapping_unevictable_pages(struct address_space *);
 241
 242extern unsigned long scan_unevictable_pages;
 243extern int scan_unevictable_handler(struct ctl_table *, int, struct file *,
 244                                        void __user *, size_t *, loff_t *);
 245extern int scan_unevictable_register_node(struct node *node);
 246extern void scan_unevictable_unregister_node(struct node *node);
 247
 248extern int kswapd_run(int nid);
 249
 250#ifdef CONFIG_MMU
 251/* linux/mm/shmem.c */
 252extern int shmem_unuse(swp_entry_t entry, struct page *page);
 253#endif /* CONFIG_MMU */
 254
 255extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 256
 257#ifdef CONFIG_SWAP
 258/* linux/mm/page_io.c */
 259extern int swap_readpage(struct page *);
 260extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 261extern void end_swap_bio_read(struct bio *bio, int err);
 262
 263/* linux/mm/swap_state.c */
 264extern struct address_space swapper_space;
 265#define total_swapcache_pages  swapper_space.nrpages
 266extern void show_swap_cache_info(void);
 267extern int add_to_swap(struct page *);
 268extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 269extern void __delete_from_swap_cache(struct page *);
 270extern void delete_from_swap_cache(struct page *);
 271extern void free_page_and_swap_cache(struct page *);
 272extern void free_pages_and_swap_cache(struct page **, int);
 273extern struct page *lookup_swap_cache(swp_entry_t);
 274extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 275                        struct vm_area_struct *vma, unsigned long addr);
 276extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 277                        struct vm_area_struct *vma, unsigned long addr);
 278
 279/* linux/mm/swapfile.c */
 280extern long nr_swap_pages;
 281extern long total_swap_pages;
 282extern void si_swapinfo(struct sysinfo *);
 283extern swp_entry_t get_swap_page(void);
 284extern swp_entry_t get_swap_page_of_type(int);
 285extern void swap_duplicate(swp_entry_t);
 286extern int swapcache_prepare(swp_entry_t);
 287extern int valid_swaphandles(swp_entry_t, unsigned long *);
 288extern void swap_free(swp_entry_t);
 289extern void swapcache_free(swp_entry_t, struct page *page);
 290extern int free_swap_and_cache(swp_entry_t);
 291extern int swap_type_of(dev_t, sector_t, struct block_device **);
 292extern unsigned int count_swap_pages(int, int);
 293extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 294extern sector_t swapdev_block(int, pgoff_t);
 295extern struct swap_info_struct *get_swap_info_struct(unsigned);
 296extern int reuse_swap_page(struct page *);
 297extern int try_to_free_swap(struct page *);
 298struct backing_dev_info;
 299
 300/* linux/mm/thrash.c */
 301extern struct mm_struct *swap_token_mm;
 302extern void grab_swap_token(struct mm_struct *);
 303extern void __put_swap_token(struct mm_struct *);
 304
 305static inline int has_swap_token(struct mm_struct *mm)
 306{
 307        return (mm == swap_token_mm);
 308}
 309
 310static inline void put_swap_token(struct mm_struct *mm)
 311{
 312        if (has_swap_token(mm))
 313                __put_swap_token(mm);
 314}
 315
 316static inline void disable_swap_token(void)
 317{
 318        put_swap_token(swap_token_mm);
 319}
 320
 321#ifdef CONFIG_CGROUP_MEM_RES_CTLR
 322extern void
 323mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
 324#else
 325static inline void
 326mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 327{
 328}
 329#endif
 330#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 331extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
 332#else
 333static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
 334{
 335}
 336#endif
 337
 338#else /* CONFIG_SWAP */
 339
 340#define nr_swap_pages                           0L
 341#define total_swap_pages                        0L
 342#define total_swapcache_pages                   0UL
 343
 344#define si_swapinfo(val) \
 345        do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 346/* only sparc can not include linux/pagemap.h in this file
 347 * so leave page_cache_release and release_pages undeclared... */
 348#define free_page_and_swap_cache(page) \
 349        page_cache_release(page)
 350#define free_pages_and_swap_cache(pages, nr) \
 351        release_pages((pages), (nr), 0);
 352
 353static inline void show_swap_cache_info(void)
 354{
 355}
 356
 357#define free_swap_and_cache(swp)        is_migration_entry(swp)
 358#define swapcache_prepare(swp)          is_migration_entry(swp)
 359
 360static inline void swap_duplicate(swp_entry_t swp)
 361{
 362}
 363
 364static inline void swap_free(swp_entry_t swp)
 365{
 366}
 367
 368static inline void swapcache_free(swp_entry_t swp, struct page *page)
 369{
 370}
 371
 372static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 373                        struct vm_area_struct *vma, unsigned long addr)
 374{
 375        return NULL;
 376}
 377
 378static inline int swap_writepage(struct page *p, struct writeback_control *wbc)
 379{
 380        return 0;
 381}
 382
 383static inline struct page *lookup_swap_cache(swp_entry_t swp)
 384{
 385        return NULL;
 386}
 387
 388static inline int add_to_swap(struct page *page)
 389{
 390        return 0;
 391}
 392
 393static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 394                                                        gfp_t gfp_mask)
 395{
 396        return -1;
 397}
 398
 399static inline void __delete_from_swap_cache(struct page *page)
 400{
 401}
 402
 403static inline void delete_from_swap_cache(struct page *page)
 404{
 405}
 406
 407#define reuse_swap_page(page)   (page_mapcount(page) == 1)
 408
 409static inline int try_to_free_swap(struct page *page)
 410{
 411        return 0;
 412}
 413
 414static inline swp_entry_t get_swap_page(void)
 415{
 416        swp_entry_t entry;
 417        entry.val = 0;
 418        return entry;
 419}
 420
 421/* linux/mm/thrash.c */
 422#define put_swap_token(mm)      do { } while (0)
 423#define grab_swap_token(mm)     do { } while (0)
 424#define has_swap_token(mm)      0
 425#define disable_swap_token()    do { } while (0)
 426
 427static inline void
 428mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
 429{
 430}
 431
 432#endif /* CONFIG_SWAP */
 433#endif /* __KERNEL__*/
 434#endif /* _LINUX_SWAP_H */
 435