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 <linux/pagemap.h>
12 #include <asm/atomic.h>
15 #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
16 #define SWAP_FLAG_PRIO_MASK 0x7fff
17 #define SWAP_FLAG_PRIO_SHIFT 0
19 static inline int current_is_kswapd(void)
21 return current
->flags
& PF_KSWAPD
;
25 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
26 * be swapped to. The swap type and the offset into that swap type are
27 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
28 * for the type means that the maximum number of swapcache pages is 27 bits
29 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
30 * the type/offset into the pte as 5/27 as well.
32 #define MAX_SWAPFILES_SHIFT 5
33 #define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
36 * Magic header for a swap area. The first part of the union is
37 * what the swap magic looks like for the old (limited to 128MB)
38 * swap area format, the second part of the union adds - in the
39 * old reserved area - some extra information. Note that the first
40 * kilobyte is reserved for boot loader or disk label stuff...
42 * Having the magic at the end of the PAGE_SIZE makes detecting swap
43 * areas somewhat tricky on machines that support multiple page sizes.
44 * For 2.5 we'll probably want to move the magic to just beyond the
49 char reserved
[PAGE_SIZE
- 10];
50 char magic
[10]; /* SWAP-SPACE or SWAPSPACE2 */
53 char bootbits
[1024]; /* Space for disklabel etc. */
55 unsigned int last_page
;
56 unsigned int nr_badpages
;
57 unsigned int padding
[125];
58 unsigned int badpages
[1];
62 /* A swap entry has to fit into a "unsigned long", as
63 * the entry is hidden in the "index" field of the
64 * swapper address space.
71 * current->reclaim_state points to one of these when a task is running
74 struct reclaim_state
{
75 unsigned long reclaimed_slab
;
82 struct writeback_control
;
86 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
87 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
88 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
89 * from setup, they're handled identically.
91 * We always assume that blocks are of size PAGE_SIZE.
94 struct list_head list
;
101 * Max bad pages in the new format..
103 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
104 #define MAX_SWAP_BADPAGES \
105 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
108 SWP_USED
= (1 << 0), /* is slot in swap_info[] used? */
109 SWP_WRITEOK
= (1 << 1), /* ok to write to this swap? */
110 SWP_ACTIVE
= (SWP_USED
| SWP_WRITEOK
),
113 #define SWAP_CLUSTER_MAX 32
115 #define SWAP_MAP_MAX 0x7fff
116 #define SWAP_MAP_BAD 0x8000
119 * The in-memory structure used to track swap areas.
120 * extent_list.prev points at the lowest-index extent. That list is
123 struct swap_info_struct
{
125 spinlock_t sdev_lock
;
126 struct file
*swap_file
;
127 struct block_device
*bdev
;
128 struct list_head extent_list
;
130 struct swap_extent
*curr_swap_extent
;
131 unsigned old_block_size
;
132 unsigned short * swap_map
;
133 unsigned int lowest_bit
;
134 unsigned int highest_bit
;
135 unsigned int cluster_next
;
136 unsigned int cluster_nr
;
137 int prio
; /* swap priority */
140 unsigned long inuse_pages
;
141 int next
; /* next entry on swap list */
145 int head
; /* head of priority-ordered swapfile list */
146 int next
; /* swapfile to be used next */
149 /* Swap 50% full? Release swapcache more aggressively.. */
150 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
152 /* linux/mm/oom_kill.c */
153 extern void out_of_memory(unsigned int __nocast gfp_mask
, int order
);
155 /* linux/mm/memory.c */
156 extern void swapin_readahead(swp_entry_t
, unsigned long, struct vm_area_struct
*);
158 /* linux/mm/page_alloc.c */
159 extern unsigned long totalram_pages
;
160 extern unsigned long totalhigh_pages
;
161 extern long nr_swap_pages
;
162 extern unsigned int nr_free_pages(void);
163 extern unsigned int nr_free_pages_pgdat(pg_data_t
*pgdat
);
164 extern unsigned int nr_free_buffer_pages(void);
165 extern unsigned int nr_free_pagecache_pages(void);
167 /* linux/mm/swap.c */
168 extern void FASTCALL(lru_cache_add(struct page
*));
169 extern void FASTCALL(lru_cache_add_active(struct page
*));
170 extern void FASTCALL(activate_page(struct page
*));
171 extern void FASTCALL(mark_page_accessed(struct page
*));
172 extern void lru_add_drain(void);
173 extern int rotate_reclaimable_page(struct page
*page
);
174 extern void swap_setup(void);
176 /* linux/mm/vmscan.c */
177 extern int try_to_free_pages(struct zone
**, unsigned int);
178 extern int zone_reclaim(struct zone
*, unsigned int, unsigned int);
179 extern int shrink_all_memory(int);
180 extern int vm_swappiness
;
183 /* linux/mm/shmem.c */
184 extern int shmem_unuse(swp_entry_t entry
, struct page
*page
);
185 #endif /* CONFIG_MMU */
187 extern void swap_unplug_io_fn(struct backing_dev_info
*, struct page
*);
190 /* linux/mm/page_io.c */
191 extern int swap_readpage(struct file
*, struct page
*);
192 extern int swap_writepage(struct page
*page
, struct writeback_control
*wbc
);
193 extern int rw_swap_page_sync(int, swp_entry_t
, struct page
*);
195 /* linux/mm/swap_state.c */
196 extern struct address_space swapper_space
;
197 #define total_swapcache_pages swapper_space.nrpages
198 extern void show_swap_cache_info(void);
199 extern int add_to_swap(struct page
*);
200 extern void __delete_from_swap_cache(struct page
*);
201 extern void delete_from_swap_cache(struct page
*);
202 extern int move_to_swap_cache(struct page
*, swp_entry_t
);
203 extern int move_from_swap_cache(struct page
*, unsigned long,
204 struct address_space
*);
205 extern void free_page_and_swap_cache(struct page
*);
206 extern void free_pages_and_swap_cache(struct page
**, int);
207 extern struct page
* lookup_swap_cache(swp_entry_t
);
208 extern struct page
* read_swap_cache_async(swp_entry_t
, struct vm_area_struct
*vma
,
210 /* linux/mm/swapfile.c */
211 extern long total_swap_pages
;
212 extern unsigned int nr_swapfiles
;
213 extern struct swap_info_struct swap_info
[];
214 extern void si_swapinfo(struct sysinfo
*);
215 extern swp_entry_t
get_swap_page(void);
216 extern int swap_duplicate(swp_entry_t
);
217 extern int valid_swaphandles(swp_entry_t
, unsigned long *);
218 extern void swap_free(swp_entry_t
);
219 extern void free_swap_and_cache(swp_entry_t
);
220 extern sector_t
map_swap_page(struct swap_info_struct
*, pgoff_t
);
221 extern struct swap_info_struct
*get_swap_info_struct(unsigned);
222 extern int can_share_swap_page(struct page
*);
223 extern int remove_exclusive_swap_page(struct page
*);
224 struct backing_dev_info
;
226 extern struct swap_list_t swap_list
;
227 extern spinlock_t swaplock
;
229 #define swap_list_lock() spin_lock(&swaplock)
230 #define swap_list_unlock() spin_unlock(&swaplock)
231 #define swap_device_lock(p) spin_lock(&p->sdev_lock)
232 #define swap_device_unlock(p) spin_unlock(&p->sdev_lock)
234 /* linux/mm/thrash.c */
235 extern struct mm_struct
* swap_token_mm
;
236 extern unsigned long swap_token_default_timeout
;
237 extern void grab_swap_token(void);
238 extern void __put_swap_token(struct mm_struct
*);
240 static inline int has_swap_token(struct mm_struct
*mm
)
242 return (mm
== swap_token_mm
);
245 static inline void put_swap_token(struct mm_struct
*mm
)
247 if (has_swap_token(mm
))
248 __put_swap_token(mm
);
251 #else /* CONFIG_SWAP */
253 #define total_swap_pages 0
254 #define total_swapcache_pages 0UL
256 #define si_swapinfo(val) \
257 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
258 #define free_page_and_swap_cache(page) \
259 page_cache_release(page)
260 #define free_pages_and_swap_cache(pages, nr) \
261 release_pages((pages), (nr), 0);
263 #define show_swap_cache_info() /*NOTHING*/
264 #define free_swap_and_cache(swp) /*NOTHING*/
265 #define swap_duplicate(swp) /*NOTHING*/
266 #define swap_free(swp) /*NOTHING*/
267 #define read_swap_cache_async(swp,vma,addr) NULL
268 #define lookup_swap_cache(swp) NULL
269 #define valid_swaphandles(swp, off) 0
270 #define can_share_swap_page(p) 0
271 #define move_to_swap_cache(p, swp) 1
272 #define move_from_swap_cache(p, i, m) 1
273 #define __delete_from_swap_cache(p) /*NOTHING*/
274 #define delete_from_swap_cache(p) /*NOTHING*/
275 #define swap_token_default_timeout 0
277 static inline int remove_exclusive_swap_page(struct page
*p
)
282 static inline swp_entry_t
get_swap_page(void)
289 /* linux/mm/thrash.c */
290 #define put_swap_token(x) do { } while(0)
291 #define grab_swap_token() do { } while(0)
292 #define has_swap_token(x) 0
294 #endif /* CONFIG_SWAP */
295 #endif /* __KERNEL__*/
296 #endif /* _LINUX_SWAP_H */