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1 | #ifndef _LINUX_PAGEMAP_H |
2 | #define _LINUX_PAGEMAP_H | |
3 | ||
4 | /* | |
5 | * Copyright 1995 Linus Torvalds | |
6 | */ | |
7 | #include <linux/mm.h> | |
8 | #include <linux/fs.h> | |
9 | #include <linux/list.h> | |
10 | #include <linux/highmem.h> | |
11 | #include <linux/compiler.h> | |
12 | #include <asm/uaccess.h> | |
13 | #include <linux/gfp.h> | |
14 | ||
15 | /* | |
16 | * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page | |
17 | * allocation mode flags. | |
18 | */ | |
19 | #define AS_EIO (__GFP_BITS_SHIFT + 0) /* IO error on async write */ | |
20 | #define AS_ENOSPC (__GFP_BITS_SHIFT + 1) /* ENOSPC on async write */ | |
21 | ||
dd0fc66f | 22 | static inline gfp_t mapping_gfp_mask(struct address_space * mapping) |
1da177e4 LT |
23 | { |
24 | return mapping->flags & __GFP_BITS_MASK; | |
25 | } | |
26 | ||
27 | /* | |
28 | * This is non-atomic. Only to be used before the mapping is activated. | |
29 | * Probably needs a barrier... | |
30 | */ | |
31 | static inline void mapping_set_gfp_mask(struct address_space *m, int mask) | |
32 | { | |
33 | m->flags = (m->flags & ~__GFP_BITS_MASK) | mask; | |
34 | } | |
35 | ||
36 | /* | |
37 | * The page cache can done in larger chunks than | |
38 | * one page, because it allows for more efficient | |
39 | * throughput (it can then be mapped into user | |
40 | * space in smaller chunks for same flexibility). | |
41 | * | |
42 | * Or rather, it _will_ be done in larger chunks. | |
43 | */ | |
44 | #define PAGE_CACHE_SHIFT PAGE_SHIFT | |
45 | #define PAGE_CACHE_SIZE PAGE_SIZE | |
46 | #define PAGE_CACHE_MASK PAGE_MASK | |
47 | #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) | |
48 | ||
49 | #define page_cache_get(page) get_page(page) | |
50 | #define page_cache_release(page) put_page(page) | |
51 | void release_pages(struct page **pages, int nr, int cold); | |
52 | ||
53 | static inline struct page *page_cache_alloc(struct address_space *x) | |
54 | { | |
0c35bbad | 55 | return alloc_pages(mapping_gfp_mask(x)|__GFP_NORECLAIM, 0); |
1da177e4 LT |
56 | } |
57 | ||
58 | static inline struct page *page_cache_alloc_cold(struct address_space *x) | |
59 | { | |
0c35bbad | 60 | return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD|__GFP_NORECLAIM, 0); |
1da177e4 LT |
61 | } |
62 | ||
63 | typedef int filler_t(void *, struct page *); | |
64 | ||
65 | extern struct page * find_get_page(struct address_space *mapping, | |
66 | unsigned long index); | |
67 | extern struct page * find_lock_page(struct address_space *mapping, | |
68 | unsigned long index); | |
69 | extern struct page * find_trylock_page(struct address_space *mapping, | |
70 | unsigned long index); | |
71 | extern struct page * find_or_create_page(struct address_space *mapping, | |
6daa0e28 | 72 | unsigned long index, gfp_t gfp_mask); |
1da177e4 LT |
73 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
74 | unsigned int nr_pages, struct page **pages); | |
75 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, | |
76 | int tag, unsigned int nr_pages, struct page **pages); | |
77 | ||
78 | /* | |
79 | * Returns locked page at given index in given cache, creating it if needed. | |
80 | */ | |
81 | static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index) | |
82 | { | |
83 | return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); | |
84 | } | |
85 | ||
86 | extern struct page * grab_cache_page_nowait(struct address_space *mapping, | |
87 | unsigned long index); | |
88 | extern struct page * read_cache_page(struct address_space *mapping, | |
89 | unsigned long index, filler_t *filler, | |
90 | void *data); | |
91 | extern int read_cache_pages(struct address_space *mapping, | |
92 | struct list_head *pages, filler_t *filler, void *data); | |
93 | ||
94 | int add_to_page_cache(struct page *page, struct address_space *mapping, | |
6daa0e28 | 95 | unsigned long index, gfp_t gfp_mask); |
1da177e4 | 96 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
6daa0e28 | 97 | unsigned long index, gfp_t gfp_mask); |
1da177e4 LT |
98 | extern void remove_from_page_cache(struct page *page); |
99 | extern void __remove_from_page_cache(struct page *page); | |
100 | ||
101 | extern atomic_t nr_pagecache; | |
102 | ||
103 | #ifdef CONFIG_SMP | |
104 | ||
105 | #define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
106 | DECLARE_PER_CPU(long, nr_pagecache_local); | |
107 | ||
108 | /* | |
109 | * pagecache_acct implements approximate accounting for pagecache. | |
110 | * vm_enough_memory() do not need high accuracy. Writers will keep | |
111 | * an offset in their per-cpu arena and will spill that into the | |
112 | * global count whenever the absolute value of the local count | |
113 | * exceeds the counter's threshold. | |
114 | * | |
115 | * MUST be protected from preemption. | |
116 | * current protection is mapping->page_lock. | |
117 | */ | |
118 | static inline void pagecache_acct(int count) | |
119 | { | |
120 | long *local; | |
121 | ||
122 | local = &__get_cpu_var(nr_pagecache_local); | |
123 | *local += count; | |
124 | if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) { | |
125 | atomic_add(*local, &nr_pagecache); | |
126 | *local = 0; | |
127 | } | |
128 | } | |
129 | ||
130 | #else | |
131 | ||
132 | static inline void pagecache_acct(int count) | |
133 | { | |
134 | atomic_add(count, &nr_pagecache); | |
135 | } | |
136 | #endif | |
137 | ||
138 | static inline unsigned long get_page_cache_size(void) | |
139 | { | |
140 | int ret = atomic_read(&nr_pagecache); | |
141 | if (unlikely(ret < 0)) | |
142 | ret = 0; | |
143 | return ret; | |
144 | } | |
145 | ||
146 | /* | |
147 | * Return byte-offset into filesystem object for page. | |
148 | */ | |
149 | static inline loff_t page_offset(struct page *page) | |
150 | { | |
151 | return ((loff_t)page->index) << PAGE_CACHE_SHIFT; | |
152 | } | |
153 | ||
154 | static inline pgoff_t linear_page_index(struct vm_area_struct *vma, | |
155 | unsigned long address) | |
156 | { | |
157 | pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT; | |
158 | pgoff += vma->vm_pgoff; | |
159 | return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
160 | } | |
161 | ||
162 | extern void FASTCALL(__lock_page(struct page *page)); | |
163 | extern void FASTCALL(unlock_page(struct page *page)); | |
164 | ||
165 | static inline void lock_page(struct page *page) | |
166 | { | |
167 | might_sleep(); | |
168 | if (TestSetPageLocked(page)) | |
169 | __lock_page(page); | |
170 | } | |
171 | ||
172 | /* | |
173 | * This is exported only for wait_on_page_locked/wait_on_page_writeback. | |
174 | * Never use this directly! | |
175 | */ | |
176 | extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr)); | |
177 | ||
178 | /* | |
179 | * Wait for a page to be unlocked. | |
180 | * | |
181 | * This must be called with the caller "holding" the page, | |
182 | * ie with increased "page->count" so that the page won't | |
183 | * go away during the wait.. | |
184 | */ | |
185 | static inline void wait_on_page_locked(struct page *page) | |
186 | { | |
187 | if (PageLocked(page)) | |
188 | wait_on_page_bit(page, PG_locked); | |
189 | } | |
190 | ||
191 | /* | |
192 | * Wait for a page to complete writeback | |
193 | */ | |
194 | static inline void wait_on_page_writeback(struct page *page) | |
195 | { | |
196 | if (PageWriteback(page)) | |
197 | wait_on_page_bit(page, PG_writeback); | |
198 | } | |
199 | ||
200 | extern void end_page_writeback(struct page *page); | |
201 | ||
202 | /* | |
203 | * Fault a userspace page into pagetables. Return non-zero on a fault. | |
204 | * | |
205 | * This assumes that two userspace pages are always sufficient. That's | |
206 | * not true if PAGE_CACHE_SIZE > PAGE_SIZE. | |
207 | */ | |
208 | static inline int fault_in_pages_writeable(char __user *uaddr, int size) | |
209 | { | |
210 | int ret; | |
211 | ||
212 | /* | |
213 | * Writing zeroes into userspace here is OK, because we know that if | |
214 | * the zero gets there, we'll be overwriting it. | |
215 | */ | |
216 | ret = __put_user(0, uaddr); | |
217 | if (ret == 0) { | |
218 | char __user *end = uaddr + size - 1; | |
219 | ||
220 | /* | |
221 | * If the page was already mapped, this will get a cache miss | |
222 | * for sure, so try to avoid doing it. | |
223 | */ | |
224 | if (((unsigned long)uaddr & PAGE_MASK) != | |
225 | ((unsigned long)end & PAGE_MASK)) | |
226 | ret = __put_user(0, end); | |
227 | } | |
228 | return ret; | |
229 | } | |
230 | ||
231 | static inline void fault_in_pages_readable(const char __user *uaddr, int size) | |
232 | { | |
233 | volatile char c; | |
234 | int ret; | |
235 | ||
236 | ret = __get_user(c, uaddr); | |
237 | if (ret == 0) { | |
238 | const char __user *end = uaddr + size - 1; | |
239 | ||
240 | if (((unsigned long)uaddr & PAGE_MASK) != | |
241 | ((unsigned long)end & PAGE_MASK)) | |
242 | __get_user(c, end); | |
243 | } | |
244 | } | |
245 | ||
246 | #endif /* _LINUX_PAGEMAP_H */ |