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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 */ | |
7906d00c | 23 | #define AS_MM_ALL_LOCKS (__GFP_BITS_SHIFT + 2) /* under mm_take_all_locks() */ |
1da177e4 | 24 | |
3e9f45bd GC |
25 | static inline void mapping_set_error(struct address_space *mapping, int error) |
26 | { | |
2185e69f | 27 | if (unlikely(error)) { |
3e9f45bd GC |
28 | if (error == -ENOSPC) |
29 | set_bit(AS_ENOSPC, &mapping->flags); | |
30 | else | |
31 | set_bit(AS_EIO, &mapping->flags); | |
32 | } | |
33 | } | |
34 | ||
dd0fc66f | 35 | static inline gfp_t mapping_gfp_mask(struct address_space * mapping) |
1da177e4 | 36 | { |
260b2367 | 37 | return (__force gfp_t)mapping->flags & __GFP_BITS_MASK; |
1da177e4 LT |
38 | } |
39 | ||
40 | /* | |
41 | * This is non-atomic. Only to be used before the mapping is activated. | |
42 | * Probably needs a barrier... | |
43 | */ | |
260b2367 | 44 | static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) |
1da177e4 | 45 | { |
260b2367 AV |
46 | m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) | |
47 | (__force unsigned long)mask; | |
1da177e4 LT |
48 | } |
49 | ||
50 | /* | |
51 | * The page cache can done in larger chunks than | |
52 | * one page, because it allows for more efficient | |
53 | * throughput (it can then be mapped into user | |
54 | * space in smaller chunks for same flexibility). | |
55 | * | |
56 | * Or rather, it _will_ be done in larger chunks. | |
57 | */ | |
58 | #define PAGE_CACHE_SHIFT PAGE_SHIFT | |
59 | #define PAGE_CACHE_SIZE PAGE_SIZE | |
60 | #define PAGE_CACHE_MASK PAGE_MASK | |
61 | #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) | |
62 | ||
63 | #define page_cache_get(page) get_page(page) | |
64 | #define page_cache_release(page) put_page(page) | |
65 | void release_pages(struct page **pages, int nr, int cold); | |
66 | ||
e286781d NP |
67 | /* |
68 | * speculatively take a reference to a page. | |
69 | * If the page is free (_count == 0), then _count is untouched, and 0 | |
70 | * is returned. Otherwise, _count is incremented by 1 and 1 is returned. | |
71 | * | |
72 | * This function must be called inside the same rcu_read_lock() section as has | |
73 | * been used to lookup the page in the pagecache radix-tree (or page table): | |
74 | * this allows allocators to use a synchronize_rcu() to stabilize _count. | |
75 | * | |
76 | * Unless an RCU grace period has passed, the count of all pages coming out | |
77 | * of the allocator must be considered unstable. page_count may return higher | |
78 | * than expected, and put_page must be able to do the right thing when the | |
79 | * page has been finished with, no matter what it is subsequently allocated | |
80 | * for (because put_page is what is used here to drop an invalid speculative | |
81 | * reference). | |
82 | * | |
83 | * This is the interesting part of the lockless pagecache (and lockless | |
84 | * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) | |
85 | * has the following pattern: | |
86 | * 1. find page in radix tree | |
87 | * 2. conditionally increment refcount | |
88 | * 3. check the page is still in pagecache (if no, goto 1) | |
89 | * | |
90 | * Remove-side that cares about stability of _count (eg. reclaim) has the | |
91 | * following (with tree_lock held for write): | |
92 | * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) | |
93 | * B. remove page from pagecache | |
94 | * C. free the page | |
95 | * | |
96 | * There are 2 critical interleavings that matter: | |
97 | * - 2 runs before A: in this case, A sees elevated refcount and bails out | |
98 | * - A runs before 2: in this case, 2 sees zero refcount and retries; | |
99 | * subsequently, B will complete and 1 will find no page, causing the | |
100 | * lookup to return NULL. | |
101 | * | |
102 | * It is possible that between 1 and 2, the page is removed then the exact same | |
103 | * page is inserted into the same position in pagecache. That's OK: the | |
104 | * old find_get_page using tree_lock could equally have run before or after | |
105 | * such a re-insertion, depending on order that locks are granted. | |
106 | * | |
107 | * Lookups racing against pagecache insertion isn't a big problem: either 1 | |
108 | * will find the page or it will not. Likewise, the old find_get_page could run | |
109 | * either before the insertion or afterwards, depending on timing. | |
110 | */ | |
111 | static inline int page_cache_get_speculative(struct page *page) | |
112 | { | |
113 | VM_BUG_ON(in_interrupt()); | |
114 | ||
115 | #if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) | |
116 | # ifdef CONFIG_PREEMPT | |
117 | VM_BUG_ON(!in_atomic()); | |
118 | # endif | |
119 | /* | |
120 | * Preempt must be disabled here - we rely on rcu_read_lock doing | |
121 | * this for us. | |
122 | * | |
123 | * Pagecache won't be truncated from interrupt context, so if we have | |
124 | * found a page in the radix tree here, we have pinned its refcount by | |
125 | * disabling preempt, and hence no need for the "speculative get" that | |
126 | * SMP requires. | |
127 | */ | |
128 | VM_BUG_ON(page_count(page) == 0); | |
129 | atomic_inc(&page->_count); | |
130 | ||
131 | #else | |
132 | if (unlikely(!get_page_unless_zero(page))) { | |
133 | /* | |
134 | * Either the page has been freed, or will be freed. | |
135 | * In either case, retry here and the caller should | |
136 | * do the right thing (see comments above). | |
137 | */ | |
138 | return 0; | |
139 | } | |
140 | #endif | |
141 | VM_BUG_ON(PageTail(page)); | |
142 | ||
143 | return 1; | |
144 | } | |
145 | ||
ce0ad7f0 NP |
146 | /* |
147 | * Same as above, but add instead of inc (could just be merged) | |
148 | */ | |
149 | static inline int page_cache_add_speculative(struct page *page, int count) | |
150 | { | |
151 | VM_BUG_ON(in_interrupt()); | |
152 | ||
153 | #if !defined(CONFIG_SMP) && defined(CONFIG_CLASSIC_RCU) | |
154 | # ifdef CONFIG_PREEMPT | |
155 | VM_BUG_ON(!in_atomic()); | |
156 | # endif | |
157 | VM_BUG_ON(page_count(page) == 0); | |
158 | atomic_add(count, &page->_count); | |
159 | ||
160 | #else | |
161 | if (unlikely(!atomic_add_unless(&page->_count, count, 0))) | |
162 | return 0; | |
163 | #endif | |
164 | VM_BUG_ON(PageCompound(page) && page != compound_head(page)); | |
165 | ||
166 | return 1; | |
167 | } | |
168 | ||
e286781d NP |
169 | static inline int page_freeze_refs(struct page *page, int count) |
170 | { | |
171 | return likely(atomic_cmpxchg(&page->_count, count, 0) == count); | |
172 | } | |
173 | ||
174 | static inline void page_unfreeze_refs(struct page *page, int count) | |
175 | { | |
176 | VM_BUG_ON(page_count(page) != 0); | |
177 | VM_BUG_ON(count == 0); | |
178 | ||
179 | atomic_set(&page->_count, count); | |
180 | } | |
181 | ||
44110fe3 | 182 | #ifdef CONFIG_NUMA |
2ae88149 | 183 | extern struct page *__page_cache_alloc(gfp_t gfp); |
44110fe3 | 184 | #else |
2ae88149 NP |
185 | static inline struct page *__page_cache_alloc(gfp_t gfp) |
186 | { | |
187 | return alloc_pages(gfp, 0); | |
188 | } | |
189 | #endif | |
190 | ||
1da177e4 LT |
191 | static inline struct page *page_cache_alloc(struct address_space *x) |
192 | { | |
2ae88149 | 193 | return __page_cache_alloc(mapping_gfp_mask(x)); |
1da177e4 LT |
194 | } |
195 | ||
196 | static inline struct page *page_cache_alloc_cold(struct address_space *x) | |
197 | { | |
2ae88149 | 198 | return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); |
1da177e4 LT |
199 | } |
200 | ||
201 | typedef int filler_t(void *, struct page *); | |
202 | ||
203 | extern struct page * find_get_page(struct address_space *mapping, | |
57f6b96c | 204 | pgoff_t index); |
1da177e4 | 205 | extern struct page * find_lock_page(struct address_space *mapping, |
57f6b96c | 206 | pgoff_t index); |
1da177e4 | 207 | extern struct page * find_or_create_page(struct address_space *mapping, |
57f6b96c | 208 | pgoff_t index, gfp_t gfp_mask); |
1da177e4 LT |
209 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start, |
210 | unsigned int nr_pages, struct page **pages); | |
ebf43500 JA |
211 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, |
212 | unsigned int nr_pages, struct page **pages); | |
1da177e4 LT |
213 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, |
214 | int tag, unsigned int nr_pages, struct page **pages); | |
215 | ||
afddba49 NP |
216 | struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index); |
217 | ||
1da177e4 LT |
218 | /* |
219 | * Returns locked page at given index in given cache, creating it if needed. | |
220 | */ | |
57f6b96c FW |
221 | static inline struct page *grab_cache_page(struct address_space *mapping, |
222 | pgoff_t index) | |
1da177e4 LT |
223 | { |
224 | return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); | |
225 | } | |
226 | ||
227 | extern struct page * grab_cache_page_nowait(struct address_space *mapping, | |
57f6b96c | 228 | pgoff_t index); |
6fe6900e | 229 | extern struct page * read_cache_page_async(struct address_space *mapping, |
57f6b96c | 230 | pgoff_t index, filler_t *filler, |
6fe6900e | 231 | void *data); |
1da177e4 | 232 | extern struct page * read_cache_page(struct address_space *mapping, |
57f6b96c | 233 | pgoff_t index, filler_t *filler, |
1da177e4 LT |
234 | void *data); |
235 | extern int read_cache_pages(struct address_space *mapping, | |
236 | struct list_head *pages, filler_t *filler, void *data); | |
237 | ||
6fe6900e NP |
238 | static inline struct page *read_mapping_page_async( |
239 | struct address_space *mapping, | |
57f6b96c | 240 | pgoff_t index, void *data) |
6fe6900e NP |
241 | { |
242 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
243 | return read_cache_page_async(mapping, index, filler, data); | |
244 | } | |
245 | ||
090d2b18 | 246 | static inline struct page *read_mapping_page(struct address_space *mapping, |
57f6b96c | 247 | pgoff_t index, void *data) |
090d2b18 PE |
248 | { |
249 | filler_t *filler = (filler_t *)mapping->a_ops->readpage; | |
250 | return read_cache_page(mapping, index, filler, data); | |
251 | } | |
252 | ||
1da177e4 LT |
253 | /* |
254 | * Return byte-offset into filesystem object for page. | |
255 | */ | |
256 | static inline loff_t page_offset(struct page *page) | |
257 | { | |
258 | return ((loff_t)page->index) << PAGE_CACHE_SHIFT; | |
259 | } | |
260 | ||
261 | static inline pgoff_t linear_page_index(struct vm_area_struct *vma, | |
262 | unsigned long address) | |
263 | { | |
264 | pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT; | |
265 | pgoff += vma->vm_pgoff; | |
266 | return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
267 | } | |
268 | ||
b3c97528 HH |
269 | extern void __lock_page(struct page *page); |
270 | extern int __lock_page_killable(struct page *page); | |
271 | extern void __lock_page_nosync(struct page *page); | |
272 | extern void unlock_page(struct page *page); | |
1da177e4 | 273 | |
529ae9aa NP |
274 | static inline void set_page_locked(struct page *page) |
275 | { | |
276 | set_bit(PG_locked, &page->flags); | |
277 | } | |
278 | ||
279 | static inline void clear_page_locked(struct page *page) | |
280 | { | |
281 | clear_bit(PG_locked, &page->flags); | |
282 | } | |
283 | ||
284 | static inline int trylock_page(struct page *page) | |
285 | { | |
286 | return !test_and_set_bit(PG_locked, &page->flags); | |
287 | } | |
288 | ||
db37648c NP |
289 | /* |
290 | * lock_page may only be called if we have the page's inode pinned. | |
291 | */ | |
1da177e4 LT |
292 | static inline void lock_page(struct page *page) |
293 | { | |
294 | might_sleep(); | |
529ae9aa | 295 | if (!trylock_page(page)) |
1da177e4 LT |
296 | __lock_page(page); |
297 | } | |
db37648c | 298 | |
2687a356 MW |
299 | /* |
300 | * lock_page_killable is like lock_page but can be interrupted by fatal | |
301 | * signals. It returns 0 if it locked the page and -EINTR if it was | |
302 | * killed while waiting. | |
303 | */ | |
304 | static inline int lock_page_killable(struct page *page) | |
305 | { | |
306 | might_sleep(); | |
529ae9aa | 307 | if (!trylock_page(page)) |
2687a356 MW |
308 | return __lock_page_killable(page); |
309 | return 0; | |
310 | } | |
311 | ||
db37648c NP |
312 | /* |
313 | * lock_page_nosync should only be used if we can't pin the page's inode. | |
314 | * Doesn't play quite so well with block device plugging. | |
315 | */ | |
316 | static inline void lock_page_nosync(struct page *page) | |
317 | { | |
318 | might_sleep(); | |
529ae9aa | 319 | if (!trylock_page(page)) |
db37648c NP |
320 | __lock_page_nosync(page); |
321 | } | |
1da177e4 LT |
322 | |
323 | /* | |
324 | * This is exported only for wait_on_page_locked/wait_on_page_writeback. | |
325 | * Never use this directly! | |
326 | */ | |
b3c97528 | 327 | extern void wait_on_page_bit(struct page *page, int bit_nr); |
1da177e4 LT |
328 | |
329 | /* | |
330 | * Wait for a page to be unlocked. | |
331 | * | |
332 | * This must be called with the caller "holding" the page, | |
333 | * ie with increased "page->count" so that the page won't | |
334 | * go away during the wait.. | |
335 | */ | |
336 | static inline void wait_on_page_locked(struct page *page) | |
337 | { | |
338 | if (PageLocked(page)) | |
339 | wait_on_page_bit(page, PG_locked); | |
340 | } | |
341 | ||
342 | /* | |
343 | * Wait for a page to complete writeback | |
344 | */ | |
345 | static inline void wait_on_page_writeback(struct page *page) | |
346 | { | |
347 | if (PageWriteback(page)) | |
348 | wait_on_page_bit(page, PG_writeback); | |
349 | } | |
350 | ||
351 | extern void end_page_writeback(struct page *page); | |
352 | ||
353 | /* | |
354 | * Fault a userspace page into pagetables. Return non-zero on a fault. | |
355 | * | |
356 | * This assumes that two userspace pages are always sufficient. That's | |
357 | * not true if PAGE_CACHE_SIZE > PAGE_SIZE. | |
358 | */ | |
359 | static inline int fault_in_pages_writeable(char __user *uaddr, int size) | |
360 | { | |
361 | int ret; | |
362 | ||
08291429 NP |
363 | if (unlikely(size == 0)) |
364 | return 0; | |
365 | ||
1da177e4 LT |
366 | /* |
367 | * Writing zeroes into userspace here is OK, because we know that if | |
368 | * the zero gets there, we'll be overwriting it. | |
369 | */ | |
370 | ret = __put_user(0, uaddr); | |
371 | if (ret == 0) { | |
372 | char __user *end = uaddr + size - 1; | |
373 | ||
374 | /* | |
375 | * If the page was already mapped, this will get a cache miss | |
376 | * for sure, so try to avoid doing it. | |
377 | */ | |
378 | if (((unsigned long)uaddr & PAGE_MASK) != | |
379 | ((unsigned long)end & PAGE_MASK)) | |
380 | ret = __put_user(0, end); | |
381 | } | |
382 | return ret; | |
383 | } | |
384 | ||
08291429 | 385 | static inline int fault_in_pages_readable(const char __user *uaddr, int size) |
1da177e4 LT |
386 | { |
387 | volatile char c; | |
388 | int ret; | |
389 | ||
08291429 NP |
390 | if (unlikely(size == 0)) |
391 | return 0; | |
392 | ||
1da177e4 LT |
393 | ret = __get_user(c, uaddr); |
394 | if (ret == 0) { | |
395 | const char __user *end = uaddr + size - 1; | |
396 | ||
397 | if (((unsigned long)uaddr & PAGE_MASK) != | |
398 | ((unsigned long)end & PAGE_MASK)) | |
08291429 | 399 | ret = __get_user(c, end); |
1da177e4 | 400 | } |
08291429 | 401 | return ret; |
1da177e4 LT |
402 | } |
403 | ||
529ae9aa NP |
404 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping, |
405 | pgoff_t index, gfp_t gfp_mask); | |
406 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping, | |
407 | pgoff_t index, gfp_t gfp_mask); | |
408 | extern void remove_from_page_cache(struct page *page); | |
409 | extern void __remove_from_page_cache(struct page *page); | |
410 | ||
411 | /* | |
412 | * Like add_to_page_cache_locked, but used to add newly allocated pages: | |
413 | * the page is new, so we can just run set_page_locked() against it. | |
414 | */ | |
415 | static inline int add_to_page_cache(struct page *page, | |
416 | struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) | |
417 | { | |
418 | int error; | |
419 | ||
420 | set_page_locked(page); | |
421 | error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); | |
422 | if (unlikely(error)) | |
423 | clear_page_locked(page); | |
424 | return error; | |
425 | } | |
426 | ||
1da177e4 | 427 | #endif /* _LINUX_PAGEMAP_H */ |