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 unsigned long swap_token_default_timeout;
234 extern void grab_swap_token(void);
235 extern void __put_swap_token(struct mm_struct *);
236
237 static inline int has_swap_token(struct mm_struct *mm)
238 {
239 return (mm == swap_token_mm);
240 }
241
242 static inline void put_swap_token(struct mm_struct *mm)
243 {
244 if (has_swap_token(mm))
245 __put_swap_token(mm);
246 }
247
248 #else /* CONFIG_SWAP */
249
250 #define total_swap_pages 0
251 #define total_swapcache_pages 0UL
252
253 #define si_swapinfo(val) \
254 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
255 #define free_page_and_swap_cache(page) \
256 page_cache_release(page)
257 #define free_pages_and_swap_cache(pages, nr) \
258 release_pages((pages), (nr), 0);
259
260 #define show_swap_cache_info() /*NOTHING*/
261 #define free_swap_and_cache(swp) /*NOTHING*/
262 #define swap_duplicate(swp) /*NOTHING*/
263 #define swap_free(swp) /*NOTHING*/
264 #define read_swap_cache_async(swp,vma,addr) NULL
265 #define lookup_swap_cache(swp) NULL
266 #define valid_swaphandles(swp, off) 0
267 #define can_share_swap_page(p) 0
268 #define move_to_swap_cache(p, swp) 1
269 #define move_from_swap_cache(p, i, m) 1
270 #define __delete_from_swap_cache(p) /*NOTHING*/
271 #define delete_from_swap_cache(p) /*NOTHING*/
272 #define swap_token_default_timeout 0
273
274 static inline int remove_exclusive_swap_page(struct page *p)
275 {
276 return 0;
277 }
278
279 static inline swp_entry_t get_swap_page(void)
280 {
281 swp_entry_t entry;
282 entry.val = 0;
283 return entry;
284 }
285
286 /* linux/mm/thrash.c */
287 #define put_swap_token(x) do { } while(0)
288 #define grab_swap_token() do { } while(0)
289 #define has_swap_token(x) 0
290
291 #endif /* CONFIG_SWAP */
292 #endif /* __KERNEL__*/
293 #endif /* _LINUX_SWAP_H */
294
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