include/linux/swap.h

   1 #ifndef _LINUX_SWAP_H
   2 #define _LINUX_SWAP_H
   3
   4 #include <linux/config.h>
   5 #include <linux/spinlock.h>
   6 #include <linux/linkage.h>
   7 #include <linux/mmzone.h>
   8 #include <linux/list.h>
   9 #include <linux/sched.h>
  10
  11 #include <asm/atomic.h>
  12 #include <asm/page.h>
  13
  14 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  15 #define SWAP_FLAG_PRIO_MASK     0x7fff
  16 #define SWAP_FLAG_PRIO_SHIFT    0
  17
  18 static inline int current_is_kswapd(void)
  19 {
  20         return current->flags & PF_KSWAPD;
  21 }
  22
  23 /*
  24  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  25  * be swapped to.  The swap type and the offset into that swap type are
  26  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  27  * for the type means that the maximum number of swapcache pages is 27 bits
  28  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  29  * the type/offset into the pte as 5/27 as well.
  30  */
  31 #define MAX_SWAPFILES_SHIFT     5
  32 #define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  33
  34 /*
  35  * Magic header for a swap area. The first part of the union is
  36  * what the swap magic looks like for the old (limited to 128MB)
  37  * swap area format, the second part of the union adds - in the
  38  * old reserved area - some extra information. Note that the first
  39  * kilobyte is reserved for boot loader or disk label stuff...
  40  *
  41  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  42  * areas somewhat tricky on machines that support multiple page sizes.
  43  * For 2.5 we'll probably want to move the magic to just beyond the
  44  * bootbits...
  45  */
  46 union swap_header {
  47         struct {
  48                 char reserved[PAGE_SIZE - 10];
  49                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  50         } magic;
  51         struct {
  52                 char         bootbits[1024];    /* Space for disklabel etc. */
  53                 unsigned int version;
  54                 unsigned int last_page;
  55                 unsigned int nr_badpages;
  56                 unsigned int padding[125];
  57                 unsigned int badpages[1];
  58         } info;
  59 };
  60
  61  /* A swap entry has to fit into a "unsigned long", as
  62   * the entry is hidden in the "index" field of the
  63   * swapper address space.
  64   */
  65 typedef struct {
  66         unsigned long val;
  67 } swp_entry_t;
  68
  69 /*
  70  * current->reclaim_state points to one of these when a task is running
  71  * memory reclaim
  72  */
  73 struct reclaim_state {
  74         unsigned long reclaimed_slab;
  75 };
  76
  77 #ifdef __KERNEL__
  78
  79 struct address_space;
  80 struct sysinfo;
  81 struct writeback_control;
  82 struct zone;
  83
  84 /*
  85  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
  86  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
  87  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
  88  * from setup, they're handled identically.
  89  *
  90  * We always assume that blocks are of size PAGE_SIZE.
  91  */
  92 struct swap_extent {
  93         struct list_head list;
  94         pgoff_t start_page;
  95         pgoff_t nr_pages;
  96         sector_t start_block;
  97 };
  98
  99 /*
 100  * Max bad pages in the new format..
 101  */
 102 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 103 #define MAX_SWAP_BADPAGES \
 104         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 105
 106 enum {
 107         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 108         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 109         SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 110                                         /* add others here before... */
 111         SWP_SCANNING    = (1 << 8),     /* refcount in scan_swap_map */
 112 };
 113
 114 #define SWAP_CLUSTER_MAX 32
 115
 116 #define SWAP_MAP_MAX    0x7fff
 117 #define SWAP_MAP_BAD    0x8000
 118
 119 /*
 120  * The in-memory structure used to track swap areas.
 121  */
 122 struct swap_info_struct {
 123         unsigned int flags;
 124         int prio;                       /* swap priority */
 125         struct file *swap_file;
 126         struct block_device *bdev;
 127         struct list_head extent_list;
 128         struct swap_extent *curr_swap_extent;
 129         unsigned old_block_size;
 130         unsigned short * swap_map;
 131         unsigned int lowest_bit;
 132         unsigned int highest_bit;
 133         unsigned int cluster_next;
 134         unsigned int cluster_nr;
 135         unsigned int pages;
 136         unsigned int max;
 137         unsigned int inuse_pages;
 138         int next;                       /* next entry on swap list */
 139 };
 140
 141 struct swap_list_t {
 142         int head;       /* head of priority-ordered swapfile list */
 143         int next;       /* swapfile to be used next */
 144 };
 145
 146 /* Swap 50% full? Release swapcache more aggressively.. */
 147 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 148
 149 /* linux/mm/oom_kill.c */
 150 extern void out_of_memory(gfp_t gfp_mask, int order);
 151
 152 /* linux/mm/memory.c */
 153 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 154
 155 /* linux/mm/page_alloc.c */
 156 extern unsigned long totalram_pages;
 157 extern unsigned long totalhigh_pages;
 158 extern long nr_swap_pages;
 159 extern unsigned int nr_free_pages(void);
 160 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
 161 extern unsigned int nr_free_buffer_pages(void);
 162 extern unsigned int nr_free_pagecache_pages(void);
 163
 164 /* linux/mm/swap.c */
 165 extern void FASTCALL(lru_cache_add(struct page *));
 166 extern void FASTCALL(lru_cache_add_active(struct page *));
 167 extern void FASTCALL(activate_page(struct page *));
 168 extern void FASTCALL(mark_page_accessed(struct page *));
 169 extern void lru_add_drain(void);
 170 extern int rotate_reclaimable_page(struct page *page);
 171 extern void swap_setup(void);
 172
 173 /* linux/mm/vmscan.c */
 174 extern int try_to_free_pages(struct zone **, gfp_t);
 175 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
 176 extern int shrink_all_memory(int);
 177 extern int vm_swappiness;
 178
 179 #ifdef CONFIG_MMU
 180 /* linux/mm/shmem.c */
 181 extern int shmem_unuse(swp_entry_t entry, struct page *page);
 182 #endif /* CONFIG_MMU */
 183
 184 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 185
 186 #ifdef CONFIG_SWAP
 187 /* linux/mm/page_io.c */
 188 extern int swap_readpage(struct file *, struct page *);
 189 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
 190 extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
 191
 192 /* linux/mm/swap_state.c */
 193 extern struct address_space swapper_space;
 194 #define total_swapcache_pages  swapper_space.nrpages
 195 extern void show_swap_cache_info(void);
 196 extern int add_to_swap(struct page *);
 197 extern void __delete_from_swap_cache(struct page *);
 198 extern void delete_from_swap_cache(struct page *);
 199 extern int move_to_swap_cache(struct page *, swp_entry_t);
 200 extern int move_from_swap_cache(struct page *, unsigned long,
 201                 struct address_space *);
 202 extern void free_page_and_swap_cache(struct page *);
 203 extern void free_pages_and_swap_cache(struct page **, int);
 204 extern struct page * lookup_swap_cache(swp_entry_t);
 205 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 206                                            unsigned long addr);
 207 /* linux/mm/swapfile.c */
 208 extern long total_swap_pages;
 209 extern unsigned int nr_swapfiles;
 210 extern struct swap_info_struct swap_info[];
 211 extern void si_swapinfo(struct sysinfo *);
 212 extern swp_entry_t get_swap_page(void);
 213 extern int swap_duplicate(swp_entry_t);
 214 extern int valid_swaphandles(swp_entry_t, unsigned long *);
 215 extern void swap_free(swp_entry_t);
 216 extern void free_swap_and_cache(swp_entry_t);
 217 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
 218 extern struct swap_info_struct *get_swap_info_struct(unsigned);
 219 extern int can_share_swap_page(struct page *);
 220 extern int remove_exclusive_swap_page(struct page *);
 221 struct backing_dev_info;
 222
 223 extern spinlock_t swap_lock;
 224
 225 /* linux/mm/thrash.c */
 226 extern struct mm_struct * swap_token_mm;
 227 extern unsigned long swap_token_default_timeout;
 228 extern void grab_swap_token(void);
 229 extern void __put_swap_token(struct mm_struct *);
 230
 231 static inline int has_swap_token(struct mm_struct *mm)
 232 {
 233         return (mm == swap_token_mm);
 234 }
 235
 236 static inline void put_swap_token(struct mm_struct *mm)
 237 {
 238         if (has_swap_token(mm))
 239                 __put_swap_token(mm);
 240 }
 241
 242 static inline void disable_swap_token(void)
 243 {
 244         put_swap_token(swap_token_mm);
 245 }
 246
 247 #else /* CONFIG_SWAP */
 248
 249 #define total_swap_pages                        0
 250 #define total_swapcache_pages                   0UL
 251
 252 #define si_swapinfo(val) \
 253         do { (val)->freeswap = (val)->totalswap = 0; } while (0)
 254 /* only sparc can not include linux/pagemap.h in this file
 255  * so leave page_cache_release and release_pages undeclared... */
 256 #define free_page_and_swap_cache(page) \
 257         page_cache_release(page)
 258 #define free_pages_and_swap_cache(pages, nr) \
 259         release_pages((pages), (nr), 0);
 260
 261 #define show_swap_cache_info()                  /*NOTHING*/
 262 #define free_swap_and_cache(swp)                /*NOTHING*/
 263 #define swap_duplicate(swp)                     /*NOTHING*/
 264 #define swap_free(swp)                          /*NOTHING*/
 265 #define read_swap_cache_async(swp,vma,addr)     NULL
 266 #define lookup_swap_cache(swp)                  NULL
 267 #define valid_swaphandles(swp, off)             0
 268 #define can_share_swap_page(p)                  0
 269 #define move_to_swap_cache(p, swp)              1
 270 #define move_from_swap_cache(p, i, m)           1
 271 #define __delete_from_swap_cache(p)             /*NOTHING*/
 272 #define delete_from_swap_cache(p)               /*NOTHING*/
 273 #define swap_token_default_timeout              0
 274
 275 static inline int remove_exclusive_swap_page(struct page *p)
 276 {
 277         return 0;
 278 }
 279
 280 static inline swp_entry_t get_swap_page(void)
 281 {
 282         swp_entry_t entry;
 283         entry.val = 0;
 284         return entry;
 285 }
 286
 287 /* linux/mm/thrash.c */
 288 #define put_swap_token(x) do { } while(0)
 289 #define grab_swap_token()  do { } while(0)
 290 #define has_swap_token(x) 0
 291 #define disable_swap_token() do { } while(0)
 292
 293 #endif /* CONFIG_SWAP */
 294 #endif /* __KERNEL__*/
 295 #endif /* _LINUX_SWAP_H */