1 #ifndef _LINUX_SWAP_H
2 #define _LINUX_SWAP_H
3
4 #include <linux/spinlock.h>
5 #include <linux/linkage.h>
6 #include <linux/mmzone.h>
7 #include <linux/list.h>
8 #include <linux/memcontrol.h>
9 #include <linux/sched.h>
10
11 #include <asm/atomic.h>
12 #include <asm/page.h>
13
14 struct notifier_block;
15
16 struct bio;
17
18 #define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
19 #define SWAP_FLAG_PRIO_MASK 0x7fff
20 #define SWAP_FLAG_PRIO_SHIFT 0
21
22 static inline int current_is_kswapd(void)
23 {
24 return current->flags & PF_KSWAPD;
25 }
26
27 /*
28 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
29 * be swapped to. The swap type and the offset into that swap type are
30 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
31 * for the type means that the maximum number of swapcache pages is 27 bits
32 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
33 * the type/offset into the pte as 5/27 as well.
34 */
35 #define MAX_SWAPFILES_SHIFT 5
36 #ifndef CONFIG_MIGRATION
37 #define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
38 #else
39 /* Use last two entries for page migration swap entries */
40 #define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT)-2)
41 #define SWP_MIGRATION_READ MAX_SWAPFILES
42 #define SWP_MIGRATION_WRITE (MAX_SWAPFILES + 1)
43 #endif
44
45 /*
46 * Magic header for a swap area. The first part of the union is
47 * what the swap magic looks like for the old (limited to 128MB)
48 * swap area format, the second part of the union adds - in the
49 * old reserved area - some extra information. Note that the first
50 * kilobyte is reserved for boot loader or disk label stuff...
51 *
52 * Having the magic at the end of the PAGE_SIZE makes detecting swap
53 * areas somewhat tricky on machines that support multiple page sizes.
54 * For 2.5 we'll probably want to move the magic to just beyond the
55 * bootbits...
56 */
57 union swap_header {
58 struct {
59 char reserved[PAGE_SIZE - 10];
60 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
61 } magic;
62 struct {
63 char bootbits[1024]; /* Space for disklabel etc. */
64 __u32 version;
65 __u32 last_page;
66 __u32 nr_badpages;
67 unsigned char sws_uuid[16];
68 unsigned char sws_volume[16];
69 __u32 padding[117];
70 __u32 badpages[1];
71 } info;
72 };
73
74 /* A swap entry has to fit into a "unsigned long", as
75 * the entry is hidden in the "index" field of the
76 * swapper address space.
77 */
78 typedef struct {
79 unsigned long val;
80 } swp_entry_t;
81
82 /*
83 * current->reclaim_state points to one of these when a task is running
84 * memory reclaim
85 */
86 struct reclaim_state {
87 unsigned long reclaimed_slab;
88 };
89
90 #ifdef __KERNEL__
91
92 struct address_space;
93 struct sysinfo;
94 struct writeback_control;
95 struct zone;
96
97 /*
98 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
99 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
100 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
101 * from setup, they're handled identically.
102 *
103 * We always assume that blocks are of size PAGE_SIZE.
104 */
105 struct swap_extent {
106 struct list_head list;
107 pgoff_t start_page;
108 pgoff_t nr_pages;
109 sector_t start_block;
110 };
111
112 /*
113 * Max bad pages in the new format..
114 */
115 #define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
116 #define MAX_SWAP_BADPAGES \
117 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
118
119 enum {
120 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
121 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
122 SWP_ACTIVE = (SWP_USED | SWP_WRITEOK),
123 /* add others here before... */
124 SWP_SCANNING = (1 << 8), /* refcount in scan_swap_map */
125 };
126
127 #define SWAP_CLUSTER_MAX 32
128
129 #define SWAP_MAP_MAX 0x7fff
130 #define SWAP_MAP_BAD 0x8000
131
132 /*
133 * The in-memory structure used to track swap areas.
134 */
135 struct swap_info_struct {
136 unsigned int flags;
137 int prio; /* swap priority */
138 struct file *swap_file;
139 struct block_device *bdev;
140 struct list_head extent_list;
141 struct swap_extent *curr_swap_extent;
142 unsigned old_block_size;
143 unsigned short * swap_map;
144 unsigned int lowest_bit;
145 unsigned int highest_bit;
146 unsigned int cluster_next;
147 unsigned int cluster_nr;
148 unsigned int pages;
149 unsigned int max;
150 unsigned int inuse_pages;
151 int next; /* next entry on swap list */
152 };
153
154 struct swap_list_t {
155 int head; /* head of priority-ordered swapfile list */
156 int next; /* swapfile to be used next */
157 };
158
159 /* Swap 50% full? Release swapcache more aggressively.. */
160 #define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
161
162 /* linux/mm/page_alloc.c */
163 extern unsigned long totalram_pages;
164 extern unsigned long totalreserve_pages;
165 extern long nr_swap_pages;
166 extern unsigned int nr_free_buffer_pages(void);
167 extern unsigned int nr_free_pagecache_pages(void);
168
169 /* Definition of global_page_state not available yet */
170 #define nr_free_pages() global_page_state(NR_FREE_PAGES)
171
172
173 /* linux/mm/swap.c */
174 extern void lru_cache_add(struct page *);
175 extern void lru_cache_add_active(struct page *);
176 extern void activate_page(struct page *);
177 extern void mark_page_accessed(struct page *);
178 extern void lru_add_drain(void);
179 extern int lru_add_drain_all(void);
180 extern int rotate_reclaimable_page(struct page *page);
181 extern void swap_setup(void);
182
183 /* linux/mm/vmscan.c */
184 extern unsigned long try_to_free_pages(struct zone **zones, int order,
185 gfp_t gfp_mask);
186 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *mem,
187 gfp_t gfp_mask);
188 extern int __isolate_lru_page(struct page *page, int mode);
189 extern unsigned long shrink_all_memory(unsigned long nr_pages);
190 extern int vm_swappiness;
191 extern int remove_mapping(struct address_space *mapping, struct page *page);
192 extern long vm_total_pages;
193
194 #ifdef CONFIG_NUMA
195 extern int zone_reclaim_mode;
196 extern int sysctl_min_unmapped_ratio;
197 extern int sysctl_min_slab_ratio;
198 extern int zone_reclaim(struct zone *, gfp_t, unsigned int);
199 #else
200 #define zone_reclaim_mode 0
201 static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
202 {
203 return 0;
204 }
205 #endif
206
207 extern int kswapd_run(int nid);
208
209 #ifdef CONFIG_MMU
210 /* linux/mm/shmem.c */
211 extern int shmem_unuse(swp_entry_t entry, struct page *page);
212 #endif /* CONFIG_MMU */
213
214 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
215
216 #ifdef CONFIG_SWAP
217 /* linux/mm/page_io.c */
218 extern int swap_readpage(struct file *, struct page *);
219 extern int swap_writepage(struct page *page, struct writeback_control *wbc);
220 extern void end_swap_bio_read(struct bio *bio, int err);
221
222 /* linux/mm/swap_state.c */
223 extern struct address_space swapper_space;
224 #define total_swapcache_pages swapper_space.nrpages
225 extern void show_swap_cache_info(void);
226 extern int add_to_swap(struct page *, gfp_t);
227 extern int add_to_swap_cache(struct page *, swp_entry_t, gfp_t);
228 extern void __delete_from_swap_cache(struct page *);
229 extern void delete_from_swap_cache(struct page *);
230 extern void free_page_and_swap_cache(struct page *);
231 extern void free_pages_and_swap_cache(struct page **, int);
232 extern struct page *lookup_swap_cache(swp_entry_t);
233 extern struct page *read_swap_cache_async(swp_entry_t, gfp_t,
234 struct vm_area_struct *vma, unsigned long addr);
235 extern struct page *swapin_readahead(swp_entry_t, gfp_t,
236 struct vm_area_struct *vma, unsigned long addr);
237
238 /* linux/mm/swapfile.c */
239 extern long total_swap_pages;
240 extern unsigned int nr_swapfiles;
241 extern void si_swapinfo(struct sysinfo *);
242 extern swp_entry_t get_swap_page(void);
243 extern swp_entry_t get_swap_page_of_type(int);
244 extern int swap_duplicate(swp_entry_t);
245 extern int valid_swaphandles(swp_entry_t, unsigned long *);
246 extern void swap_free(swp_entry_t);
247 extern void free_swap_and_cache(swp_entry_t);
248 extern int swap_type_of(dev_t, sector_t, struct block_device **);
249 extern unsigned int count_swap_pages(int, int);
250 extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
251 extern sector_t swapdev_block(int, pgoff_t);
252 extern struct swap_info_struct *get_swap_info_struct(unsigned);
253 extern int can_share_swap_page(struct page *);
254 extern int remove_exclusive_swap_page(struct page *);
255 struct backing_dev_info;
256
257 extern spinlock_t swap_lock;
258
259 /* linux/mm/thrash.c */
260 extern struct mm_struct * swap_token_mm;
261 extern void grab_swap_token(void);
262 extern void __put_swap_token(struct mm_struct *);
263
264 static inline int has_swap_token(struct mm_struct *mm)
265 {
266 return (mm == swap_token_mm);
267 }
268
269 static inline void put_swap_token(struct mm_struct *mm)
270 {
271 if (has_swap_token(mm))
272 __put_swap_token(mm);
273 }
274
275 static inline void disable_swap_token(void)
276 {
277 put_swap_token(swap_token_mm);
278 }
279
280 #else /* CONFIG_SWAP */
281
282 #define total_swap_pages 0
283 #define total_swapcache_pages 0UL
284
285 #define si_swapinfo(val) \
286 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
287 /* only sparc can not include linux/pagemap.h in this file
288 * so leave page_cache_release and release_pages undeclared... */
289 #define free_page_and_swap_cache(page) \
290 page_cache_release(page)
291 #define free_pages_and_swap_cache(pages, nr) \
292 release_pages((pages), (nr), 0);
293
294 static inline void show_swap_cache_info(void)
295 {
296 }
297
298 static inline void free_swap_and_cache(swp_entry_t swp)
299 {
300 }
301
302 static inline int swap_duplicate(swp_entry_t swp)
303 {
304 return 0;
305 }
306
307 static inline void swap_free(swp_entry_t swp)
308 {
309 }
310
311 static inline struct page *swapin_readahead(swp_entry_t swp, gfp_t gfp_mask,
312 struct vm_area_struct *vma, unsigned long addr)
313 {
314 return NULL;
315 }
316
317 static inline struct page *lookup_swap_cache(swp_entry_t swp)
318 {
319 return NULL;
320 }
321
322 #define can_share_swap_page(p) (page_mapcount(p) == 1)
323
324 static inline int add_to_swap_cache(struct page *page, swp_entry_t entry,
325 gfp_t gfp_mask)
326 {
327 return -1;
328 }
329
330 static inline void __delete_from_swap_cache(struct page *page)
331 {
332 }
333
334 static inline void delete_from_swap_cache(struct page *page)
335 {
336 }
337
338 #define swap_token_default_timeout 0
339
340 static inline int remove_exclusive_swap_page(struct page *p)
341 {
342 return 0;
343 }
344
345 static inline swp_entry_t get_swap_page(void)
346 {
347 swp_entry_t entry;
348 entry.val = 0;
349 return entry;
350 }
351
352 /* linux/mm/thrash.c */
353 #define put_swap_token(x) do { } while(0)
354 #define grab_swap_token() do { } while(0)
355 #define has_swap_token(x) 0
356 #define disable_swap_token() do { } while(0)
357
358 #endif /* CONFIG_SWAP */
359 #endif /* __KERNEL__*/
360 #endif /* _LINUX_SWAP_H */
361
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