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1da177e4 LT |
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> | |
3e9f45bd | 14 | #include <linux/bitops.h> |
e286781d | 15 | #include <linux/hardirq.h> /* for in_interrupt() */ |
1da177e4 LT |
16 | |
17 | /* | |
18 | * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page | |
19 | * allocation mode flags. | |
20 | */ | |
21 | #define AS_EIO (__GFP_BITS_SHIFT + 0) /* IO error on async write */ | |
22 | #define AS_ENOSPC (__GFP_BITS_SHIFT + 1) /* ENOSPC on async write */ | |
23 | ||
3e9f45bd GC |
24 | static inline void mapping_set_error(struct address_space *mapping, int error) |
25 | { | |
2185e69f | 26 | if (unlikely(error)) { |
3e9f45bd GC |
27 | if (error == -ENOSPC) |
28 | set_bit(AS_ENOSPC, &mapping->flags); | |
29 | else | |
30 | set_bit(AS_EIO, &mapping->flags); | |
31 | } | |
32 | } | |
33 | ||
dd0fc66f | 34 | static inline gfp_t mapping_gfp_mask(struct address_space * mapping) |
1da177e4 | 35 | { |
260b2367 | 36 | return (__force gfp_t)mapping->flags & __GFP_BITS_MASK; |
1da177e4 LT |
37 | } |
38 | ||
39 | /* | |
40 | * This is non-atomic. Only to be used before the mapping is activated. | |
41 | * Probably needs a barrier... | |
42 | */ | |
260b2367 | 43 | static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) |
1da177e4 | 44 | { |
260b2367 AV |
45 | m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) | |
46 | (__force unsigned long)mask; | |
1da177e4 LT |
47 | } |
48 | ||
49 | /* | |
50 | * The page cache can done in larger chunks than | |
51 | * one page, because it allows for more efficient | |
52 | * throughput (it can then be mapped into user | |
53 | * space in smaller chunks for same flexibility). | |
54 | * | |
55 | * Or rather, it _will_ be done in larger chunks. | |
56 | */ | |
57 | #define PAGE_CACHE_SHIFT PAGE_SHIFT | |
58 | #define PAGE_CACHE_SIZE PAGE_SIZE | |
59 | #define PAGE_CACHE_MASK PAGE_MASK | |
60 | #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) | |
61 | ||
62 | #define page_cache_get(page) get_page(page) | |
63 | #define page_cache_release(page) put_page(page) | |
64 | void release_pages(struct page **pages, int nr, int cold); | |
65 | ||
e286781d NP |
66 | /* |
67 | * speculatively take a reference to a page. | |
68 | * If the page is free (_count == 0), then _count is untouched, and 0 | |
69 | * is returned. Otherwise, _count is incremented by 1 and 1 is returned. | |
70 | * | |
71 | * This function must be called inside the same rcu_read_lock() section as has | |
72 | * been used to lookup the page in the pagecache radix-tree (or page table): | |
73 | * this allows allocators to use a synchronize_rcu() to stabilize _count. | |
74 | * | |
75 | * Unless an RCU grace period has passed, the count of all pages coming out | |
76 | * of the allocator must be considered unstable. page_count may return higher | |
77 | * than expected, and put_page must be able to do the right thing when the | |
78 | * page has been finished with, no matter what it is subsequently allocated | |
79 | * for (because put_page is what is used here to drop an invalid speculative | |
80 | * reference). | |
81 | * | |
82 | * This is the interesting part of the lockless pagecache (and lockless | |
83 | * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) | |
84 | * has the following pattern: | |
85 | * 1. find page in radix tree | |
86 | * 2. conditionally increment refcount | |
87 | * 3. check the page is still in pagecache (if no, goto 1) | |
88 | * | |
89 | * Remove-side that cares about stability of _count (eg. reclaim) has the | |
90 | * following (with tree_lock held for write): | |
91 | * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) | |
92 | * B. remove page from pagecache | |
93 | * C. free the page | |
94 | * | |
95 | * There are 2 critical interleavings that matter: | |
96 | * - 2 runs before A: in this case, A sees elevated refcount and bails out | |
97 | * - A runs before 2: in this case, 2 sees zero refcount and retries; | |
98 | * subsequently, B will complete and 1 will find no page, causing the | |
99 | * lookup to return NULL. | |
100 | * | |
101 | * It is possible that between 1 and 2, the page is removed then the exact same | |
102 | * page is inserted into the same position in pagecache. That's OK: the | |
103 | * old find_get_page using tree_lock could equally have run before or after | |
104 | * such a re-insertion, depending on order that locks are granted. | |
105 | * | |
106 | * Lookups racing against pagecache insertion isn't a big problem: either 1 | |
107 | * will find the page or it will not. Likewise, the old find_get_page could run | |
108 | * either before the insertion or afterwards, depending on timing. | |
109 | */ | |
110 | static inline int page_cache_get_speculative(struct page *page) | |
111 | { | |
112 | VM_BUG_ON(in_interrupt()); | |
113 | ||
114 | #if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) | |
115 | # ifdef CONFIG_PREEMPT | |
116 | VM_BUG_ON(!in_atomic()); | |
117 | # endif | |
118 | /* | |
119 | * Preempt must be disabled here - we rely on rcu_read_lock doing | |
120 | * this for us. | |
121 | * | |
122 | * Pagecache won't be truncated from interrupt context, so if we have | |
123 | * found a page in the radix tree here, we have pinned its refcount by | |
124 | * disabling preempt, and hence no need for the "speculative get" that | |
125 | * SMP requires. | |
126 | */ | |
127 | VM_BUG_ON(page_count(page) == 0); | |
128 | atomic_inc(&page->_count); | |
129 | ||
130 | #else | |
131 | if (unlikely(!get_page_unless_zero(page))) { | |
132 | /* | |
133 | * Either the page has been freed, or will be freed. | |
134 | * In either case, retry here and the caller should | |
135 | * do the right thing (see comments above). | |
136 | */ | |
137 | return 0; | |
138 | } | |
139 | #endif | |
140 | VM_BUG_ON(PageTail(page)); | |
141 | ||
142 | return 1; | |
143 | } | |
144 | ||
145 | static inline int page_freeze_refs(struct page *page, int count) | |
146 | { | |
147 | return likely(atomic_cmpxchg(&page->_count, count, 0) == count); | |
148 | } | |
149 | ||
150 | static inline void page_unfreeze_refs(struct page *page, int count) | |
151 | { | |
152 | VM_BUG_ON(page_count(page) != 0); | |
153 | VM_BUG_ON(count == 0); | |
154 | ||
155 | atomic_set(&page->_count, count); | |
156 | } | |
157 | ||
44110fe3 | 158 | #ifdef CONFIG_NUMA |
2ae88149 | 159 | extern struct page *__page_cache_alloc(gfp_t gfp); |
44110fe3 | 160 | #else |
2ae88149 NP |
161 | static inline struct page *__page_cache_alloc(gfp_t gfp) |
162 | { | |
163 | return alloc_pages(gfp, 0); | |
164 | } | |
165 | #endif | |
166 | ||
1da177e4 LT |
167 | static inline struct page *page_cache_alloc(struct address_space *x) |
168 | { | |
2ae88149 | 169 | return __page_cache_alloc(mapping_gfp_mask(x)); |
1da177e4 LT |
170 | } |
171 | ||
172 | static inline struct page *page_cache_alloc_cold(struct address_space *x) | |
173 | { | |
2ae88149 | 174 | return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); |
1da177e4 LT |
175 | } |
176 | ||
177 | typedef int filler_t(void *, struct page *); | |
178 | ||
179 | extern struct page * find_get_page(struct address_space *mapping, | |
57f6b96c | 180 | pgoff_t index); |
1da177e4 | 181 | extern struct page * find_lock_page(struct address_space *mapping, |
57f6b96c | 182 | pgoff_t index); |
1da177e4 | 183 | extern struct page * find_or_create_page(struct address_space *mapping, |
57f6b96c | 184 | pgoff_t index, gfp_t gfp_mask); |
1da177e4 LT |
185 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
186 | unsigned int nr_pages, struct page **pages); | |
ebf43500 JA |
187 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, |
188 | unsigned int nr_pages, struct page **pages); | |
1da177e4 LT |
189 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, |
190 | int tag, unsigned int nr_pages, struct page **pages); | |
191 | ||
afddba49 NP |
192 | struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index); |
193 | ||
1da177e4 LT |
194 | /* |
195 | * Returns locked page at given index in given cache, creating it if needed. | |
196 | */ | |
57f6b96c FW |
197 | static inline struct page *grab_cache_page(struct address_space *mapping, |
198 | pgoff_t index) | |
1da177e4 LT |
199 | { |
200 | return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); | |
201 | } | |
202 | ||
203 | extern struct page * grab_cache_page_nowait(struct address_space *mapping, | |
57f6b96c | 204 | pgoff_t index); |
6fe6900e | 205 | extern struct page * read_cache_page_async(struct address_space *mapping, |
57f6b96c | 206 | pgoff_t index, filler_t *filler, |
6fe6900e | 207 | void *data); |
1da177e4 | 208 | extern struct page * read_cache_page(struct address_space *mapping, |
57f6b96c | 209 | pgoff_t index, filler_t *filler, |
1da177e4 LT |
210 | void *data); |
211 | extern int read_cache_pages(struct address_space *mapping, | |
212 | struct list_head *pages, filler_t *filler, void *data); | |
213 | ||
6fe6900e NP |
214 | static inline struct page *read_mapping_page_async( |
215 | struct address_space *mapping, | |
57f6b96c | 216 | pgoff_t index, void *data) |
6fe6900e NP |
217 | { |
218 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
219 | return read_cache_page_async(mapping, index, filler, data); | |
220 | } | |
221 | ||
090d2b18 | 222 | static inline struct page *read_mapping_page(struct address_space *mapping, |
57f6b96c | 223 | pgoff_t index, void *data) |
090d2b18 PE |
224 | { |
225 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
226 | return read_cache_page(mapping, index, filler, data); | |
227 | } | |
228 | ||
e286781d | 229 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
57f6b96c | 230 | pgoff_t index, gfp_t gfp_mask); |
1da177e4 | 231 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, |
57f6b96c | 232 | pgoff_t index, gfp_t gfp_mask); |
1da177e4 LT |
233 | extern void remove_from_page_cache(struct page *page); |
234 | extern void __remove_from_page_cache(struct page *page); | |
235 | ||
e286781d NP |
236 | /* |
237 | * Like add_to_page_cache_locked, but used to add newly allocated pages: | |
238 | * the page is new, so we can just run SetPageLocked() against it. | |
239 | */ | |
240 | static inline int add_to_page_cache(struct page *page, | |
241 | struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) | |
242 | { | |
243 | int error; | |
244 | ||
245 | SetPageLocked(page); | |
246 | error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); | |
247 | if (unlikely(error)) | |
248 | ClearPageLocked(page); | |
249 | return error; | |
250 | } | |
251 | ||
1da177e4 LT |
252 | /* |
253 | * Return byte-offset into filesystem object for page. | |
254 | */ | |
255 | static inline loff_t page_offset(struct page *page) | |
256 | { | |
257 | return ((loff_t)page->index) << PAGE_CACHE_SHIFT; | |
258 | } | |
259 | ||
260 | static inline pgoff_t linear_page_index(struct vm_area_struct *vma, | |
261 | unsigned long address) | |
262 | { | |
263 | pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT; | |
264 | pgoff += vma->vm_pgoff; | |
265 | return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
266 | } | |
267 | ||
b3c97528 HH |
268 | extern void __lock_page(struct page *page); |
269 | extern int __lock_page_killable(struct page *page); | |
270 | extern void __lock_page_nosync(struct page *page); | |
271 | extern void unlock_page(struct page *page); | |
1da177e4 | 272 | |
db37648c NP |
273 | /* |
274 | * lock_page may only be called if we have the page's inode pinned. | |
275 | */ | |
1da177e4 LT |
276 | static inline void lock_page(struct page *page) |
277 | { | |
278 | might_sleep(); | |
279 | if (TestSetPageLocked(page)) | |
280 | __lock_page(page); | |
281 | } | |
db37648c | 282 | |
2687a356 MW |
283 | /* |
284 | * lock_page_killable is like lock_page but can be interrupted by fatal | |
285 | * signals. It returns 0 if it locked the page and -EINTR if it was | |
286 | * killed while waiting. | |
287 | */ | |
288 | static inline int lock_page_killable(struct page *page) | |
289 | { | |
290 | might_sleep(); | |
291 | if (TestSetPageLocked(page)) | |
292 | return __lock_page_killable(page); | |
293 | return 0; | |
294 | } | |
295 | ||
db37648c NP |
296 | /* |
297 | * lock_page_nosync should only be used if we can't pin the page's inode. | |
298 | * Doesn't play quite so well with block device plugging. | |
299 | */ | |
300 | static inline void lock_page_nosync(struct page *page) | |
301 | { | |
302 | might_sleep(); | |
303 | if (TestSetPageLocked(page)) | |
304 | __lock_page_nosync(page); | |
305 | } | |
1da177e4 LT |
306 | |
307 | /* | |
308 | * This is exported only for wait_on_page_locked/wait_on_page_writeback. | |
309 | * Never use this directly! | |
310 | */ | |
b3c97528 | 311 | extern void wait_on_page_bit(struct page *page, int bit_nr); |
1da177e4 LT |
312 | |
313 | /* | |
314 | * Wait for a page to be unlocked. | |
315 | * | |
316 | * This must be called with the caller "holding" the page, | |
317 | * ie with increased "page->count" so that the page won't | |
318 | * go away during the wait.. | |
319 | */ | |
320 | static inline void wait_on_page_locked(struct page *page) | |
321 | { | |
322 | if (PageLocked(page)) | |
323 | wait_on_page_bit(page, PG_locked); | |
324 | } | |
325 | ||
326 | /* | |
327 | * Wait for a page to complete writeback | |
328 | */ | |
329 | static inline void wait_on_page_writeback(struct page *page) | |
330 | { | |
331 | if (PageWriteback(page)) | |
332 | wait_on_page_bit(page, PG_writeback); | |
333 | } | |
334 | ||
335 | extern void end_page_writeback(struct page *page); | |
336 | ||
337 | /* | |
338 | * Fault a userspace page into pagetables. Return non-zero on a fault. | |
339 | * | |
340 | * This assumes that two userspace pages are always sufficient. That's | |
341 | * not true if PAGE_CACHE_SIZE > PAGE_SIZE. | |
342 | */ | |
343 | static inline int fault_in_pages_writeable(char __user *uaddr, int size) | |
344 | { | |
345 | int ret; | |
346 | ||
08291429 NP |
347 | if (unlikely(size == 0)) |
348 | return 0; | |
349 | ||
1da177e4 LT |
350 | /* |
351 | * Writing zeroes into userspace here is OK, because we know that if | |
352 | * the zero gets there, we'll be overwriting it. | |
353 | */ | |
354 | ret = __put_user(0, uaddr); | |
355 | if (ret == 0) { | |
356 | char __user *end = uaddr + size - 1; | |
357 | ||
358 | /* | |
359 | * If the page was already mapped, this will get a cache miss | |
360 | * for sure, so try to avoid doing it. | |
361 | */ | |
362 | if (((unsigned long)uaddr & PAGE_MASK) != | |
363 | ((unsigned long)end & PAGE_MASK)) | |
364 | ret = __put_user(0, end); | |
365 | } | |
366 | return ret; | |
367 | } | |
368 | ||
08291429 | 369 | static inline int fault_in_pages_readable(const char __user *uaddr, int size) |
1da177e4 LT |
370 | { |
371 | volatile char c; | |
372 | int ret; | |
373 | ||
08291429 NP |
374 | if (unlikely(size == 0)) |
375 | return 0; | |
376 | ||
1da177e4 LT |
377 | ret = __get_user(c, uaddr); |
378 | if (ret == 0) { | |
379 | const char __user *end = uaddr + size - 1; | |
380 | ||
381 | if (((unsigned long)uaddr & PAGE_MASK) != | |
382 | ((unsigned long)end & PAGE_MASK)) | |
08291429 | 383 | ret = __get_user(c, end); |
1da177e4 | 384 | } |
08291429 | 385 | return ret; |
1da177e4 LT |
386 | } |
387 | ||
388 | #endif /* _LINUX_PAGEMAP_H */ |