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
  11#include <asm/atomic.h>
  12#include <asm/page.h>
  13
  14struct notifier_block;
  15
  16struct 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
  22static 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 */
  57union 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  */
  78typedef 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 */
  86struct reclaim_state {
  87        unsigned long reclaimed_slab;
  88};
  89
  90#ifdef __KERNEL__
  91
  92struct address_space;
  93struct sysinfo;
  94struct writeback_control;
  95struct 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 */
 105struct 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
 119enum {
 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 */
 135struct 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
 154struct 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/page_alloc.c */
 163extern unsigned long totalram_pages;
 164extern unsigned long totalreserve_pages;
 165extern long nr_swap_pages;
 166extern unsigned int nr_free_buffer_pages(void);
 167extern unsigned int nr_free_pagecache_pages(void);
 168
 169/* Definition of global_page_state not available yet */
 170#define nr_free_pages() global_page_state(NR_FREE_PAGES)
 171
 172
 173/* linux/mm/swap.c */
 174extern void lru_cache_add(struct page *);
 175extern void lru_cache_add_active(struct page *);
 176extern void activate_page(struct page *);
 177extern void mark_page_accessed(struct page *);
 178extern void lru_add_drain(void);
 179extern int lru_add_drain_all(void);
 180extern void 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 zonelist *zonelist, int order,
 185                                        gfp_t gfp_mask);
 186extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
 187                                                        gfp_t gfp_mask);
 188extern int __isolate_lru_page(struct page *page, int mode);
 189extern unsigned long shrink_all_memory(unsigned long nr_pages);
 190extern int vm_swappiness;
 191extern int remove_mapping(struct address_space *mapping, struct page *page);
 192extern long vm_total_pages;
 193
 194#ifdef CONFIG_NUMA
 195extern int zone_reclaim_mode;
 196extern int sysctl_min_unmapped_ratio;
 197extern int sysctl_min_slab_ratio;
 198extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 199#else
 200#define zone_reclaim_mode 0
 201static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 202{
 203        return 0;
 204}
 205#endif
 206
 207extern int kswapd_run(int nid);
 208
 209#ifdef CONFIG_MMU
 210/* linux/mm/shmem.c */
 211extern int shmem_unuse(swp_entry_t entry, struct page *page);
 212#endif /* CONFIG_MMU */
 213
 214extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 215
 216#ifdef CONFIG_SWAP
 217/* linux/mm/page_io.c */
 218extern int swap_readpage(struct file *, struct page *);
 219extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 220extern void end_swap_bio_read(struct bio *bio, int err);
 221
 222/* linux/mm/swap_state.c */
 223extern struct address_space swapper_space;
 224#define total_swapcache_pages  swapper_space.nrpages
 225extern void show_swap_cache_info(void);
 226extern int add_to_swap(struct page *, gfp_t);
 227extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
 228extern void __delete_from_swap_cache(struct page *);
 229extern void delete_from_swap_cache(struct page *);
 230extern void free_page_and_swap_cache(struct page *);
 231extern void free_pages_and_swap_cache(struct page **, int);
 232extern struct page *lookup_swap_cache(swp_entry_t);
 233extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
 234                        struct vm_area_struct *vma, unsigned long addr);
 235extern struct page *swapin_readahead(swp_entry_t, gfp_t,
 236                        struct vm_area_struct *vma, unsigned long addr);
 237
 238/* linux/mm/swapfile.c */
 239extern long total_swap_pages;
 240extern void si_swapinfo(struct sysinfo *);
 241extern swp_entry_t get_swap_page(void);
 242extern swp_entry_t get_swap_page_of_type(int);
 243extern int swap_duplicate(swp_entry_t);
 244extern int valid_swaphandles(swp_entry_t, unsigned long *);
 245extern void swap_free(swp_entry_t);
 246extern void free_swap_and_cache(swp_entry_t);
 247extern int swap_type_of(dev_t, sector_t, struct block_device **);
 248extern unsigned int count_swap_pages(int, int);
 249extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 250extern sector_t swapdev_block(int, pgoff_t);
 251extern struct swap_info_struct *get_swap_info_struct(unsigned);
 252extern int can_share_swap_page(struct page *);
 253extern int remove_exclusive_swap_page(struct page *);
 254struct backing_dev_info;
 255
 256/* linux/mm/thrash.c */
 257extern struct mm_struct * swap_token_mm;
 258extern void grab_swap_token(void);
 259extern void __put_swap_token(struct mm_struct *);
 260
 261static inline int has_swap_token(struct mm_struct *mm)
 262{
 263        return (mm == swap_token_mm);
 264}
 265
 266static inline void put_swap_token(struct mm_struct *mm)
 267{
 268        if (has_swap_token(mm))
 269                __put_swap_token(mm);
 270}
 271
 272static inline void disable_swap_token(void)
 273{
 274        put_swap_token(swap_token_mm);
 275}
 276
 277#else /* CONFIG_SWAP */
 278
 279#define total_swap_pages                        0
 280#define total_swapcache_pages                   0UL
 281
 282#define si_swapinfo(val) \
 283        do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 284/* only sparc can not include linux/pagemap.h in this file
 285 * so leave page_cache_release and release_pages undeclared... */
 286#define free_page_and_swap_cache(page) \
 287        page_cache_release(page)
 288#define free_pages_and_swap_cache(pages, nr) \
 289        release_pages((pages), (nr), 0);
 290
 291static inline void show_swap_cache_info(void)
 292{
 293}
 294
 295static inline void free_swap_and_cache(swp_entry_t swp)
 296{
 297}
 298
 299static inline int swap_duplicate(swp_entry_t swp)
 300{
 301        return 0;
 302}
 303
 304static inline void swap_free(swp_entry_t swp)
 305{
 306}
 307
 308static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
 309                        struct vm_area_struct *vma, unsigned long addr)
 310{
 311        return NULL;
 312}
 313
 314static inline struct page *lookup_swap_cache(swp_entry_t swp)
 315{
 316        return NULL;
 317}
 318
 319#define can_share_swap_page(p)                  (page_mapcount(p) == 1)
 320
 321static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
 322                                                        gfp_t gfp_mask)
 323{
 324        return -1;
 325}
 326
 327static inline void __delete_from_swap_cache(struct page *page)
 328{
 329}
 330
 331static inline void delete_from_swap_cache(struct page *page)
 332{
 333}
 334
 335#define swap_token_default_timeout              0
 336
 337static inline int remove_exclusive_swap_page(struct page *p)
 338{
 339        return 0;
 340}
 341
 342static inline swp_entry_t get_swap_page(void)
 343{
 344        swp_entry_t entry;
 345        entry.val = 0;
 346        return entry;
 347}
 348
 349/* linux/mm/thrash.c */
 350#define put_swap_token(x) do { } while(0)
 351#define grab_swap_token()  do { } while(0)
 352#define has_swap_token(x) 0
 353#define disable_swap_token() do { } while(0)
 354
 355#endif /* CONFIG_SWAP */
 356#endif /* __KERNEL__*/
 357#endif /* _LINUX_SWAP_H */
 358