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 #include <asm/atomic.h>
  11 #include <asm/page.h>
  12
  13 #define SWAP_FLAG_PREFER        0x8000  /* set if swap priority specified */
  14 #define SWAP_FLAG_PRIO_MASK     0x7fff
  15 #define SWAP_FLAG_PRIO_SHIFT    0
  16
  17 static inline int current_is_kswapd(void)
  18 {
  19         return current->flags & PF_KSWAPD;
  20 }
  21
  22 /*
  23  * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
  24  * be swapped to.  The swap type and the offset into that swap type are
  25  * encoded into pte's and into pgoff_t's in the swapcache.  Using five bits
  26  * for the type means that the maximum number of swapcache pages is 27 bits
  27  * on 32-bit-pgoff_t architectures.  And that assumes that the architecture packs
  28  * the type/offset into the pte as 5/27 as well.
  29  */
  30 #define MAX_SWAPFILES_SHIFT     5
  31 #define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
  32
  33 /*
  34  * Magic header for a swap area. The first part of the union is
  35  * what the swap magic looks like for the old (limited to 128MB)
  36  * swap area format, the second part of the union adds - in the
  37  * old reserved area - some extra information. Note that the first
  38  * kilobyte is reserved for boot loader or disk label stuff...
  39  *
  40  * Having the magic at the end of the PAGE_SIZE makes detecting swap
  41  * areas somewhat tricky on machines that support multiple page sizes.
  42  * For 2.5 we'll probably want to move the magic to just beyond the
  43  * bootbits...
  44  */
  45 union swap_header {
  46         struct {
  47                 char reserved[PAGE_SIZE - 10];
  48                 char magic[10];                 /* SWAP-SPACE or SWAPSPACE2 */
  49         } magic;
  50         struct {
  51                 char         bootbits[1024];    /* Space for disklabel etc. */
  52                 unsigned int version;
  53                 unsigned int last_page;
  54                 unsigned int nr_badpages;
  55                 unsigned int padding[125];
  56                 unsigned int badpages[1];
  57         } info;
  58 };
  59
  60  /* A swap entry has to fit into a "unsigned long", as
  61   * the entry is hidden in the "index" field of the
  62   * swapper address space.
  63   */
  64 typedef struct {
  65         unsigned long val;
  66 } swp_entry_t;
  67
  68 /*
  69  * current->reclaim_state points to one of these when a task is running
  70  * memory reclaim
  71  */
  72 struct reclaim_state {
  73         unsigned long reclaimed_slab;
  74 };
  75
  76 #ifdef __KERNEL__
  77
  78 struct address_space;
  79 struct sysinfo;
  80 struct writeback_control;
  81 struct zone;
  82
  83 /*
  84  * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
  85  * disk blocks.  A list of swap extents maps the entire swapfile.  (Where the
  86  * term `swapfile' refers to either a blockdevice or an IS_REG file.  Apart
  87  * from setup, they're handled identically.
  88  *
  89  * We always assume that blocks are of size PAGE_SIZE.
  90  */
  91 struct swap_extent {
  92         struct list_head list;
  93         pgoff_t start_page;
  94         pgoff_t nr_pages;
  95         sector_t start_block;
  96 };
  97
  98 /*
  99  * Max bad pages in the new format..
 100  */
 101 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
 102 #define MAX_SWAP_BADPAGES \
 103         ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
 104
 105 enum {
 106         SWP_USED        = (1 << 0),     /* is slot in swap_info[] used? */
 107         SWP_WRITEOK     = (1 << 1),     /* ok to write to this swap?    */
 108         SWP_ACTIVE      = (SWP_USED | SWP_WRITEOK),
 109 };
 110
 111 #define SWAP_CLUSTER_MAX 32
 112
 113 #define SWAP_MAP_MAX    0x7fff
 114 #define SWAP_MAP_BAD    0x8000
 115
 116 /*
 117  * The in-memory structure used to track swap areas.
 118  * extent_list.prev points at the lowest-index extent.  That list is
 119  * sorted.
 120  */
 121 struct swap_info_struct {
 122         unsigned int flags;
 123         spinlock_t sdev_lock;
 124         struct file *swap_file;
 125         struct block_device *bdev;
 126         struct list_head extent_list;
 127         int nr_extents;
 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         int prio;                       /* swap priority */
 136         int pages;
 137         unsigned long max;
 138         unsigned long inuse_pages;
 139         int next;                       /* next entry on swap list */
 140 };
 141
 142 struct swap_list_t {
 143         int head;       /* head of priority-ordered swapfile list */
 144         int next;       /* swapfile to be used next */
 145 };
 146
 147 /* Swap 50% full? Release swapcache more aggressively.. */
 148 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
 149
 150 /* linux/mm/oom_kill.c */
 151 extern void out_of_memory(int gfp_mask);
 152
 153 /* linux/mm/memory.c */
 154 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 155
 156 /* linux/mm/page_alloc.c */
 157 extern unsigned long totalram_pages;
 158 extern unsigned long totalhigh_pages;
 159 extern long nr_swap_pages;
 160 extern unsigned int nr_free_pages(void);
 161 extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
 162 extern unsigned int nr_free_buffer_pages(void);
 163 extern unsigned int nr_free_pagecache_pages(void);
 164
 165 /* linux/mm/swap.c */
 166 extern void FASTCALL(lru_cache_add(struct page *));
 167 extern void FASTCALL(lru_cache_add_active(struct page *));
 168 extern void FASTCALL(activate_page(struct page *));
 169 extern void FASTCALL(mark_page_accessed(struct page *));
 170 extern void lru_add_drain(void);
 171 extern int rotate_reclaimable_page(struct page *page);
 172 extern void swap_setup(void);
 173
 174 /* linux/mm/vmscan.c */
 175 extern int try_to_free_pages(struct zone **, unsigned int, 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 struct swap_list_t swap_list;
 224 extern spinlock_t swaplock;
 225
 226 #define swap_list_lock()        spin_lock(&swaplock)
 227 #define swap_list_unlock()      spin_unlock(&swaplock)
 228 #define swap_device_lock(p)     spin_lock(&p->sdev_lock)
 229 #define swap_device_unlock(p)   spin_unlock(&p->sdev_lock)
 230
 231 /* linux/mm/thrash.c */
 232 extern struct mm_struct * swap_token_mm;
 233 extern void grab_swap_token(void);
 234 extern void __put_swap_token(struct mm_struct *);
 235
 236 static inline int has_swap_token(struct mm_struct *mm)
 237 {
 238         return (mm == swap_token_mm);
 239 }
 240
 241 static inline void put_swap_token(struct mm_struct *mm)
 242 {
 243         if (has_swap_token(mm))
 244                 __put_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 #define free_page_and_swap_cache(page) \
 255         page_cache_release(page)
 256 #define free_pages_and_swap_cache(pages, nr) \
 257         release_pages((pages), (nr), 0);
 258
 259 #define show_swap_cache_info()                  /*NOTHING*/
 260 #define free_swap_and_cache(swp)                /*NOTHING*/
 261 #define swap_duplicate(swp)                     /*NOTHING*/
 262 #define swap_free(swp)                          /*NOTHING*/
 263 #define read_swap_cache_async(swp,vma,addr)     NULL
 264 #define lookup_swap_cache(swp)                  NULL
 265 #define valid_swaphandles(swp, off)             0
 266 #define can_share_swap_page(p)                  0
 267 #define move_to_swap_cache(p, swp)              1
 268 #define move_from_swap_cache(p, i, m)           1
 269 #define __delete_from_swap_cache(p)             /*NOTHING*/
 270 #define delete_from_swap_cache(p)               /*NOTHING*/
 271
 272 static inline int remove_exclusive_swap_page(struct page *p)
 273 {
 274         return 0;
 275 }
 276
 277 static inline swp_entry_t get_swap_page(void)
 278 {
 279         swp_entry_t entry;
 280         entry.val = 0;
 281         return entry;
 282 }
 283
 284 /* linux/mm/thrash.c */
 285 #define put_swap_token(x) do { } while(0)
 286 #define grab_swap_token()  do { } while(0)
 287 #define has_swap_token(x) 0
 288
 289 #endif /* CONFIG_SWAP */
 290 #endif /* __KERNEL__*/
 291 #endif /* _LINUX_SWAP_H */