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(unsigned int __nocast 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); 176 extern int zone_reclaim(struct zone *, unsigned int, unsigned int); 177 extern int shrink_all_memory(int); 178 extern int vm_swappiness; 179 180 #ifdef CONFIG_MMU 181 /* linux/mm/shmem.c */ 182 extern int shmem_unuse(swp_entry_t entry, struct page *page); 183 #endif /* CONFIG_MMU */ 184 185 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *); 186 187 #ifdef CONFIG_SWAP 188 /* linux/mm/page_io.c */ 189 extern int swap_readpage(struct file *, struct page *); 190 extern int swap_writepage(struct page *page, struct writeback_control *wbc); 191 extern int rw_swap_page_sync(int, swp_entry_t, struct page *); 192 193 /* linux/mm/swap_state.c */ 194 extern struct address_space swapper_space; 195 #define total_swapcache_pages swapper_space.nrpages 196 extern void show_swap_cache_info(void); 197 extern int add_to_swap(struct page *); 198 extern void __delete_from_swap_cache(struct page *); 199 extern void delete_from_swap_cache(struct page *); 200 extern int move_to_swap_cache(struct page *, swp_entry_t); 201 extern int move_from_swap_cache(struct page *, unsigned long, 202 struct address_space *); 203 extern void free_page_and_swap_cache(struct page *); 204 extern void free_pages_and_swap_cache(struct page **, int); 205 extern struct page * lookup_swap_cache(swp_entry_t); 206 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma, 207 unsigned long addr); 208 /* linux/mm/swapfile.c */ 209 extern long total_swap_pages; 210 extern unsigned int nr_swapfiles; 211 extern struct swap_info_struct swap_info[]; 212 extern void si_swapinfo(struct sysinfo *); 213 extern swp_entry_t get_swap_page(void); 214 extern int swap_duplicate(swp_entry_t); 215 extern int valid_swaphandles(swp_entry_t, unsigned long *); 216 extern void swap_free(swp_entry_t); 217 extern void free_swap_and_cache(swp_entry_t); 218 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t); 219 extern struct swap_info_struct *get_swap_info_struct(unsigned); 220 extern int can_share_swap_page(struct page *); 221 extern int remove_exclusive_swap_page(struct page *); 222 struct backing_dev_info; 223 224 extern struct swap_list_t swap_list; 225 extern spinlock_t swaplock; 226 227 #define swap_list_lock() spin_lock(&swaplock) 228 #define swap_list_unlock() spin_unlock(&swaplock) 229 #define swap_device_lock(p) spin_lock(&p->sdev_lock) 230 #define swap_device_unlock(p) spin_unlock(&p->sdev_lock) 231 232 /* linux/mm/thrash.c */ 233 extern struct mm_struct * swap_token_mm; 234 extern unsigned long swap_token_default_timeout; 235 extern void grab_swap_token(void); 236 extern void __put_swap_token(struct mm_struct *); 237 238 static inline int has_swap_token(struct mm_struct *mm) 239 { 240 return (mm == swap_token_mm); 241 } 242 243 static inline void put_swap_token(struct mm_struct *mm) 244 { 245 if (has_swap_token(mm)) 246 __put_swap_token(mm); 247 } 248 249 #else /* CONFIG_SWAP */ 250 251 #define total_swap_pages 0 252 #define total_swapcache_pages 0UL 253 254 #define si_swapinfo(val) \ 255 do { (val)->freeswap = (val)->totalswap = 0; } while (0) 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) 0 291 292 #endif /* CONFIG_SWAP */ 293 #endif /* __KERNEL__*/ 294 #endif /* _LINUX_SWAP_H */ 295