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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
11#include <asm/atomic.h>
12#include <asm/page.h>
13
14#define SWAP_FLAG_PREFER 0x8000 /* set if swap priority specified */
15#define SWAP_FLAG_PRIO_MASK 0x7fff
16#define SWAP_FLAG_PRIO_SHIFT 0
17
18static inline int current_is_kswapd(void)
19{
20 return current->flags & PF_KSWAPD;
21}
22
23/*
24 * MAX_SWAPFILES defines the maximum number of swaptypes: things which can
25 * be swapped to. The swap type and the offset into that swap type are
26 * encoded into pte's and into pgoff_t's in the swapcache. Using five bits
27 * for the type means that the maximum number of swapcache pages is 27 bits
28 * on 32-bit-pgoff_t architectures. And that assumes that the architecture packs
29 * the type/offset into the pte as 5/27 as well.
30 */
31#define MAX_SWAPFILES_SHIFT 5
32#define MAX_SWAPFILES (1 << MAX_SWAPFILES_SHIFT)
33
34/*
35 * Magic header for a swap area. The first part of the union is
36 * what the swap magic looks like for the old (limited to 128MB)
37 * swap area format, the second part of the union adds - in the
38 * old reserved area - some extra information. Note that the first
39 * kilobyte is reserved for boot loader or disk label stuff...
40 *
41 * Having the magic at the end of the PAGE_SIZE makes detecting swap
42 * areas somewhat tricky on machines that support multiple page sizes.
43 * For 2.5 we'll probably want to move the magic to just beyond the
44 * bootbits...
45 */
46union swap_header {
47 struct {
48 char reserved[PAGE_SIZE - 10];
49 char magic[10]; /* SWAP-SPACE or SWAPSPACE2 */
50 } magic;
51 struct {
52 char bootbits[1024]; /* Space for disklabel etc. */
53 unsigned int version;
54 unsigned int last_page;
55 unsigned int nr_badpages;
56 unsigned int padding[125];
57 unsigned int badpages[1];
58 } info;
59};
60
61 /* A swap entry has to fit into a "unsigned long", as
62 * the entry is hidden in the "index" field of the
63 * swapper address space.
64 */
65typedef struct {
66 unsigned long val;
67} swp_entry_t;
68
69/*
70 * current->reclaim_state points to one of these when a task is running
71 * memory reclaim
72 */
73struct reclaim_state {
74 unsigned long reclaimed_slab;
75};
76
77#ifdef __KERNEL__
78
79struct address_space;
80struct sysinfo;
81struct writeback_control;
82struct zone;
83
84/*
85 * A swap extent maps a range of a swapfile's PAGE_SIZE pages onto a range of
86 * disk blocks. A list of swap extents maps the entire swapfile. (Where the
87 * term `swapfile' refers to either a blockdevice or an IS_REG file. Apart
88 * from setup, they're handled identically.
89 *
90 * We always assume that blocks are of size PAGE_SIZE.
91 */
92struct swap_extent {
93 struct list_head list;
94 pgoff_t start_page;
95 pgoff_t nr_pages;
96 sector_t start_block;
97};
98
99/*
100 * Max bad pages in the new format..
101 */
102#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
103#define MAX_SWAP_BADPAGES \
104 ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
105
106enum {
107 SWP_USED = (1 << 0), /* is slot in swap_info[] used? */
108 SWP_WRITEOK = (1 << 1), /* ok to write to this swap? */
109 SWP_ACTIVE = (SWP_USED | SWP_WRITEOK),
110};
111
112#define SWAP_CLUSTER_MAX 32
113
114#define SWAP_MAP_MAX 0x7fff
115#define SWAP_MAP_BAD 0x8000
116
117/*
118 * The in-memory structure used to track swap areas.
119 * extent_list.prev points at the lowest-index extent. That list is
120 * sorted.
121 */
122struct swap_info_struct {
123 unsigned int flags;
124 spinlock_t sdev_lock;
125 struct file *swap_file;
126 struct block_device *bdev;
127 struct list_head extent_list;
128 int nr_extents;
129 struct swap_extent *curr_swap_extent;
130 unsigned old_block_size;
131 unsigned short * swap_map;
132 unsigned int lowest_bit;
133 unsigned int highest_bit;
134 unsigned int cluster_next;
135 unsigned int cluster_nr;
136 int prio; /* swap priority */
137 int pages;
138 unsigned long max;
139 unsigned long inuse_pages;
140 int next; /* next entry on swap list */
141};
142
143struct swap_list_t {
144 int head; /* head of priority-ordered swapfile list */
145 int next; /* swapfile to be used next */
146};
147
148/* Swap 50% full? Release swapcache more aggressively.. */
149#define vm_swap_full() (nr_swap_pages*2 < total_swap_pages)
150
151/* linux/mm/oom_kill.c */
152extern void out_of_memory(unsigned int __nocast gfp_mask, int order);
153
154/* linux/mm/memory.c */
155extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
156
157/* linux/mm/page_alloc.c */
158extern unsigned long totalram_pages;
159extern unsigned long totalhigh_pages;
160extern long nr_swap_pages;
161extern unsigned int nr_free_pages(void);
162extern unsigned int nr_free_pages_pgdat(pg_data_t *pgdat);
163extern unsigned int nr_free_buffer_pages(void);
164extern unsigned int nr_free_pagecache_pages(void);
165
166/* linux/mm/swap.c */
167extern void FASTCALL(lru_cache_add(struct page *));
168extern void FASTCALL(lru_cache_add_active(struct page *));
169extern void FASTCALL(activate_page(struct page *));
170extern void FASTCALL(mark_page_accessed(struct page *));
171extern void lru_add_drain(void);
172extern int rotate_reclaimable_page(struct page *page);
173extern void swap_setup(void);
174
175/* linux/mm/vmscan.c */
176extern int try_to_free_pages(struct zone **, unsigned int);
177extern int zone_reclaim(struct zone *, unsigned int, unsigned int);
178extern int shrink_all_memory(int);
179extern int vm_swappiness;
180
181#ifdef CONFIG_MMU
182/* linux/mm/shmem.c */
183extern int shmem_unuse(swp_entry_t entry, struct page *page);
184#endif /* CONFIG_MMU */
185
186extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
187
188#ifdef CONFIG_SWAP
189/* linux/mm/page_io.c */
190extern int swap_readpage(struct file *, struct page *);
191extern int swap_writepage(struct page *page, struct writeback_control *wbc);
192extern int rw_swap_page_sync(int, swp_entry_t, struct page *);
193
194/* linux/mm/swap_state.c */
195extern struct address_space swapper_space;
196#define total_swapcache_pages swapper_space.nrpages
197extern void show_swap_cache_info(void);
198extern int add_to_swap(struct page *);
199extern void __delete_from_swap_cache(struct page *);
200extern void delete_from_swap_cache(struct page *);
201extern int move_to_swap_cache(struct page *, swp_entry_t);
202extern int move_from_swap_cache(struct page *, unsigned long,
203 struct address_space *);
204extern void free_page_and_swap_cache(struct page *);
205extern void free_pages_and_swap_cache(struct page **, int);
206extern struct page * lookup_swap_cache(swp_entry_t);
207extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
208 unsigned long addr);
209/* linux/mm/swapfile.c */
210extern long total_swap_pages;
211extern unsigned int nr_swapfiles;
212extern struct swap_info_struct swap_info[];
213extern void si_swapinfo(struct sysinfo *);
214extern swp_entry_t get_swap_page(void);
215extern int swap_duplicate(swp_entry_t);
216extern int valid_swaphandles(swp_entry_t, unsigned long *);
217extern void swap_free(swp_entry_t);
218extern void free_swap_and_cache(swp_entry_t);
219extern sector_t map_swap_page(struct swap_info_struct *, pgoff_t);
220extern struct swap_info_struct *get_swap_info_struct(unsigned);
221extern int can_share_swap_page(struct page *);
222extern int remove_exclusive_swap_page(struct page *);
223struct backing_dev_info;
224
225extern struct swap_list_t swap_list;
226extern spinlock_t swaplock;
227
228#define swap_list_lock() spin_lock(&swaplock)
229#define swap_list_unlock() spin_unlock(&swaplock)
230#define swap_device_lock(p) spin_lock(&p->sdev_lock)
231#define swap_device_unlock(p) spin_unlock(&p->sdev_lock)
232
233/* linux/mm/thrash.c */
234extern struct mm_struct * swap_token_mm;
235extern unsigned long swap_token_default_timeout;
236extern void grab_swap_token(void);
237extern void __put_swap_token(struct mm_struct *);
238
239static inline int has_swap_token(struct mm_struct *mm)
240{
241 return (mm == swap_token_mm);
242}
243
244static inline void put_swap_token(struct mm_struct *mm)
245{
246 if (has_swap_token(mm))
247 __put_swap_token(mm);
248}
249
250#else /* CONFIG_SWAP */
251
252#define total_swap_pages 0
253#define total_swapcache_pages 0UL
254
255#define si_swapinfo(val) \
256 do { (val)->freeswap = (val)->totalswap = 0; } while (0)
257/* only sparc can not include linux/pagemap.h in this file
258 * so leave page_cache_release and release_pages undeclared... */
259#define free_page_and_swap_cache(page) \
260 page_cache_release(page)
261#define free_pages_and_swap_cache(pages, nr) \
262 release_pages((pages), (nr), 0);
263
264#define show_swap_cache_info() /*NOTHING*/
265#define free_swap_and_cache(swp) /*NOTHING*/
266#define swap_duplicate(swp) /*NOTHING*/
267#define swap_free(swp) /*NOTHING*/
268#define read_swap_cache_async(swp,vma,addr) NULL
269#define lookup_swap_cache(swp) NULL
270#define valid_swaphandles(swp, off) 0
271#define can_share_swap_page(p) 0
272#define move_to_swap_cache(p, swp) 1
273#define move_from_swap_cache(p, i, m) 1
274#define __delete_from_swap_cache(p) /*NOTHING*/
275#define delete_from_swap_cache(p) /*NOTHING*/
276#define swap_token_default_timeout 0
277
278static inline int remove_exclusive_swap_page(struct page *p)
279{
280 return 0;
281}
282
283static inline swp_entry_t get_swap_page(void)
284{
285 swp_entry_t entry;
286 entry.val = 0;
287 return entry;
288}
289
290/* linux/mm/thrash.c */
291#define put_swap_token(x) do { } while(0)
292#define grab_swap_token() do { } while(0)
293#define has_swap_token(x) 0
294
295#endif /* CONFIG_SWAP */
296#endif /* __KERNEL__*/
297#endif /* _LINUX_SWAP_H */