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CommitLineData
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() */
8edf344c 16#include <linux/hugetlb_inline.h>
1da177e4
LT
17
18/*
19 * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
20 * allocation mode flags.
21 */
9a896c9a
LS
22enum mapping_flags {
23 AS_EIO = __GFP_BITS_SHIFT + 0, /* IO error on async write */
24 AS_ENOSPC = __GFP_BITS_SHIFT + 1, /* ENOSPC on async write */
25 AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */
9a896c9a 26 AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */
9a896c9a 27};
1da177e4 28
3e9f45bd
GC
29static inline void mapping_set_error(struct address_space *mapping, int error)
30{
2185e69f 31 if (unlikely(error)) {
3e9f45bd
GC
32 if (error == -ENOSPC)
33 set_bit(AS_ENOSPC, &mapping->flags);
34 else
35 set_bit(AS_EIO, &mapping->flags);
36 }
37}
38
ba9ddf49
LS
39static inline void mapping_set_unevictable(struct address_space *mapping)
40{
41 set_bit(AS_UNEVICTABLE, &mapping->flags);
42}
43
89e004ea
LS
44static inline void mapping_clear_unevictable(struct address_space *mapping)
45{
46 clear_bit(AS_UNEVICTABLE, &mapping->flags);
47}
48
ba9ddf49
LS
49static inline int mapping_unevictable(struct address_space *mapping)
50{
89e004ea
LS
51 if (likely(mapping))
52 return test_bit(AS_UNEVICTABLE, &mapping->flags);
53 return !!mapping;
ba9ddf49 54}
ba9ddf49 55
dd0fc66f 56static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
1da177e4 57{
260b2367 58 return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
1da177e4
LT
59}
60
61/*
62 * This is non-atomic. Only to be used before the mapping is activated.
63 * Probably needs a barrier...
64 */
260b2367 65static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
1da177e4 66{
260b2367
AV
67 m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
68 (__force unsigned long)mask;
1da177e4
LT
69}
70
71/*
72 * The page cache can done in larger chunks than
73 * one page, because it allows for more efficient
74 * throughput (it can then be mapped into user
75 * space in smaller chunks for same flexibility).
76 *
77 * Or rather, it _will_ be done in larger chunks.
78 */
79#define PAGE_CACHE_SHIFT PAGE_SHIFT
80#define PAGE_CACHE_SIZE PAGE_SIZE
81#define PAGE_CACHE_MASK PAGE_MASK
82#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
83
84#define page_cache_get(page) get_page(page)
85#define page_cache_release(page) put_page(page)
86void release_pages(struct page **pages, int nr, int cold);
87
e286781d
NP
88/*
89 * speculatively take a reference to a page.
90 * If the page is free (_count == 0), then _count is untouched, and 0
91 * is returned. Otherwise, _count is incremented by 1 and 1 is returned.
92 *
93 * This function must be called inside the same rcu_read_lock() section as has
94 * been used to lookup the page in the pagecache radix-tree (or page table):
95 * this allows allocators to use a synchronize_rcu() to stabilize _count.
96 *
97 * Unless an RCU grace period has passed, the count of all pages coming out
98 * of the allocator must be considered unstable. page_count may return higher
99 * than expected, and put_page must be able to do the right thing when the
100 * page has been finished with, no matter what it is subsequently allocated
101 * for (because put_page is what is used here to drop an invalid speculative
102 * reference).
103 *
104 * This is the interesting part of the lockless pagecache (and lockless
105 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
106 * has the following pattern:
107 * 1. find page in radix tree
108 * 2. conditionally increment refcount
109 * 3. check the page is still in pagecache (if no, goto 1)
110 *
111 * Remove-side that cares about stability of _count (eg. reclaim) has the
112 * following (with tree_lock held for write):
113 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
114 * B. remove page from pagecache
115 * C. free the page
116 *
117 * There are 2 critical interleavings that matter:
118 * - 2 runs before A: in this case, A sees elevated refcount and bails out
119 * - A runs before 2: in this case, 2 sees zero refcount and retries;
120 * subsequently, B will complete and 1 will find no page, causing the
121 * lookup to return NULL.
122 *
123 * It is possible that between 1 and 2, the page is removed then the exact same
124 * page is inserted into the same position in pagecache. That's OK: the
125 * old find_get_page using tree_lock could equally have run before or after
126 * such a re-insertion, depending on order that locks are granted.
127 *
128 * Lookups racing against pagecache insertion isn't a big problem: either 1
129 * will find the page or it will not. Likewise, the old find_get_page could run
130 * either before the insertion or afterwards, depending on timing.
131 */
132static inline int page_cache_get_speculative(struct page *page)
133{
134 VM_BUG_ON(in_interrupt());
135
b560d8ad 136#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
e286781d
NP
137# ifdef CONFIG_PREEMPT
138 VM_BUG_ON(!in_atomic());
139# endif
140 /*
141 * Preempt must be disabled here - we rely on rcu_read_lock doing
142 * this for us.
143 *
144 * Pagecache won't be truncated from interrupt context, so if we have
145 * found a page in the radix tree here, we have pinned its refcount by
146 * disabling preempt, and hence no need for the "speculative get" that
147 * SMP requires.
148 */
149 VM_BUG_ON(page_count(page) == 0);
150 atomic_inc(&page->_count);
151
152#else
153 if (unlikely(!get_page_unless_zero(page))) {
154 /*
155 * Either the page has been freed, or will be freed.
156 * In either case, retry here and the caller should
157 * do the right thing (see comments above).
158 */
159 return 0;
160 }
161#endif
162 VM_BUG_ON(PageTail(page));
163
164 return 1;
165}
166
ce0ad7f0
NP
167/*
168 * Same as above, but add instead of inc (could just be merged)
169 */
170static inline int page_cache_add_speculative(struct page *page, int count)
171{
172 VM_BUG_ON(in_interrupt());
173
b560d8ad 174#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
ce0ad7f0
NP
175# ifdef CONFIG_PREEMPT
176 VM_BUG_ON(!in_atomic());
177# endif
178 VM_BUG_ON(page_count(page) == 0);
179 atomic_add(count, &page->_count);
180
181#else
182 if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
183 return 0;
184#endif
185 VM_BUG_ON(PageCompound(page) && page != compound_head(page));
186
187 return 1;
188}
189
e286781d
NP
190static inline int page_freeze_refs(struct page *page, int count)
191{
192 return likely(atomic_cmpxchg(&page->_count, count, 0) == count);
193}
194
195static inline void page_unfreeze_refs(struct page *page, int count)
196{
197 VM_BUG_ON(page_count(page) != 0);
198 VM_BUG_ON(count == 0);
199
200 atomic_set(&page->_count, count);
201}
202
44110fe3 203#ifdef CONFIG_NUMA
2ae88149 204extern struct page *__page_cache_alloc(gfp_t gfp);
44110fe3 205#else
2ae88149
NP
206static inline struct page *__page_cache_alloc(gfp_t gfp)
207{
208 return alloc_pages(gfp, 0);
209}
210#endif
211
1da177e4
LT
212static inline struct page *page_cache_alloc(struct address_space *x)
213{
2ae88149 214 return __page_cache_alloc(mapping_gfp_mask(x));
1da177e4
LT
215}
216
217static inline struct page *page_cache_alloc_cold(struct address_space *x)
218{
2ae88149 219 return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
1da177e4
LT
220}
221
222typedef int filler_t(void *, struct page *);
223
224extern struct page * find_get_page(struct address_space *mapping,
57f6b96c 225 pgoff_t index);
1da177e4 226extern struct page * find_lock_page(struct address_space *mapping,
57f6b96c 227 pgoff_t index);
1da177e4 228extern struct page * find_or_create_page(struct address_space *mapping,
57f6b96c 229 pgoff_t index, gfp_t gfp_mask);
1da177e4
LT
230unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
231 unsigned int nr_pages, struct page **pages);
ebf43500
JA
232unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
233 unsigned int nr_pages, struct page **pages);
1da177e4
LT
234unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
235 int tag, unsigned int nr_pages, struct page **pages);
236
54566b2c
NP
237struct page *grab_cache_page_write_begin(struct address_space *mapping,
238 pgoff_t index, unsigned flags);
afddba49 239
1da177e4
LT
240/*
241 * Returns locked page at given index in given cache, creating it if needed.
242 */
57f6b96c
FW
243static inline struct page *grab_cache_page(struct address_space *mapping,
244 pgoff_t index)
1da177e4
LT
245{
246 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
247}
248
249extern struct page * grab_cache_page_nowait(struct address_space *mapping,
57f6b96c 250 pgoff_t index);
6fe6900e 251extern struct page * read_cache_page_async(struct address_space *mapping,
57f6b96c 252 pgoff_t index, filler_t *filler,
6fe6900e 253 void *data);
1da177e4 254extern struct page * read_cache_page(struct address_space *mapping,
57f6b96c 255 pgoff_t index, filler_t *filler,
1da177e4 256 void *data);
0531b2aa
LT
257extern struct page * read_cache_page_gfp(struct address_space *mapping,
258 pgoff_t index, gfp_t gfp_mask);
1da177e4
LT
259extern int read_cache_pages(struct address_space *mapping,
260 struct list_head *pages, filler_t *filler, void *data);
261
6fe6900e
NP
262static inline struct page *read_mapping_page_async(
263 struct address_space *mapping,
57f6b96c 264 pgoff_t index, void *data)
6fe6900e
NP
265{
266 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
267 return read_cache_page_async(mapping, index, filler, data);
268}
269
090d2b18 270static inline struct page *read_mapping_page(struct address_space *mapping,
57f6b96c 271 pgoff_t index, void *data)
090d2b18
PE
272{
273 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
274 return read_cache_page(mapping, index, filler, data);
275}
276
1da177e4
LT
277/*
278 * Return byte-offset into filesystem object for page.
279 */
280static inline loff_t page_offset(struct page *page)
281{
282 return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
283}
284
0fe6e20b
NH
285extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
286 unsigned long address);
287
1da177e4
LT
288static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
289 unsigned long address)
290{
0fe6e20b
NH
291 pgoff_t pgoff;
292 if (unlikely(is_vm_hugetlb_page(vma)))
293 return linear_hugepage_index(vma, address);
294 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
1da177e4
LT
295 pgoff += vma->vm_pgoff;
296 return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
297}
298
b3c97528
HH
299extern void __lock_page(struct page *page);
300extern int __lock_page_killable(struct page *page);
301extern void __lock_page_nosync(struct page *page);
d065bd81
ML
302extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
303 unsigned int flags);
b3c97528 304extern void unlock_page(struct page *page);
1da177e4 305
f45840b5 306static inline void __set_page_locked(struct page *page)
529ae9aa 307{
f45840b5 308 __set_bit(PG_locked, &page->flags);
529ae9aa
NP
309}
310
f45840b5 311static inline void __clear_page_locked(struct page *page)
529ae9aa 312{
f45840b5 313 __clear_bit(PG_locked, &page->flags);
529ae9aa
NP
314}
315
316static inline int trylock_page(struct page *page)
317{
8413ac9d 318 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
529ae9aa
NP
319}
320
db37648c
NP
321/*
322 * lock_page may only be called if we have the page's inode pinned.
323 */
1da177e4
LT
324static inline void lock_page(struct page *page)
325{
326 might_sleep();
529ae9aa 327 if (!trylock_page(page))
1da177e4
LT
328 __lock_page(page);
329}
db37648c 330
2687a356
MW
331/*
332 * lock_page_killable is like lock_page but can be interrupted by fatal
333 * signals. It returns 0 if it locked the page and -EINTR if it was
334 * killed while waiting.
335 */
336static inline int lock_page_killable(struct page *page)
337{
338 might_sleep();
529ae9aa 339 if (!trylock_page(page))
2687a356
MW
340 return __lock_page_killable(page);
341 return 0;
342}
343
db37648c
NP
344/*
345 * lock_page_nosync should only be used if we can't pin the page's inode.
346 * Doesn't play quite so well with block device plugging.
347 */
348static inline void lock_page_nosync(struct page *page)
349{
350 might_sleep();
529ae9aa 351 if (!trylock_page(page))
db37648c
NP
352 __lock_page_nosync(page);
353}
1da177e4 354
d065bd81
ML
355/*
356 * lock_page_or_retry - Lock the page, unless this would block and the
357 * caller indicated that it can handle a retry.
358 */
359static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
360 unsigned int flags)
361{
362 might_sleep();
363 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
364}
365
1da177e4
LT
366/*
367 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
368 * Never use this directly!
369 */
b3c97528 370extern void wait_on_page_bit(struct page *page, int bit_nr);
1da177e4
LT
371
372/*
373 * Wait for a page to be unlocked.
374 *
375 * This must be called with the caller "holding" the page,
376 * ie with increased "page->count" so that the page won't
377 * go away during the wait..
378 */
379static inline void wait_on_page_locked(struct page *page)
380{
381 if (PageLocked(page))
382 wait_on_page_bit(page, PG_locked);
383}
384
385/*
386 * Wait for a page to complete writeback
387 */
388static inline void wait_on_page_writeback(struct page *page)
389{
390 if (PageWriteback(page))
391 wait_on_page_bit(page, PG_writeback);
392}
393
394extern void end_page_writeback(struct page *page);
395
385e1ca5
DH
396/*
397 * Add an arbitrary waiter to a page's wait queue
398 */
399extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter);
400
1da177e4
LT
401/*
402 * Fault a userspace page into pagetables. Return non-zero on a fault.
403 *
404 * This assumes that two userspace pages are always sufficient. That's
405 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
406 */
407static inline int fault_in_pages_writeable(char __user *uaddr, int size)
408{
409 int ret;
410
08291429
NP
411 if (unlikely(size == 0))
412 return 0;
413
1da177e4
LT
414 /*
415 * Writing zeroes into userspace here is OK, because we know that if
416 * the zero gets there, we'll be overwriting it.
417 */
418 ret = __put_user(0, uaddr);
419 if (ret == 0) {
420 char __user *end = uaddr + size - 1;
421
422 /*
423 * If the page was already mapped, this will get a cache miss
424 * for sure, so try to avoid doing it.
425 */
426 if (((unsigned long)uaddr & PAGE_MASK) !=
427 ((unsigned long)end & PAGE_MASK))
428 ret = __put_user(0, end);
429 }
430 return ret;
431}
432
08291429 433static inline int fault_in_pages_readable(const char __user *uaddr, int size)
1da177e4
LT
434{
435 volatile char c;
436 int ret;
437
08291429
NP
438 if (unlikely(size == 0))
439 return 0;
440
1da177e4
LT
441 ret = __get_user(c, uaddr);
442 if (ret == 0) {
443 const char __user *end = uaddr + size - 1;
444
445 if (((unsigned long)uaddr & PAGE_MASK) !=
627295e4 446 ((unsigned long)end & PAGE_MASK)) {
08291429 447 ret = __get_user(c, end);
627295e4
AK
448 (void)c;
449 }
1da177e4 450 }
08291429 451 return ret;
1da177e4
LT
452}
453
529ae9aa
NP
454int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
455 pgoff_t index, gfp_t gfp_mask);
456int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
457 pgoff_t index, gfp_t gfp_mask);
458extern void remove_from_page_cache(struct page *page);
459extern void __remove_from_page_cache(struct page *page);
460
461/*
462 * Like add_to_page_cache_locked, but used to add newly allocated pages:
f45840b5 463 * the page is new, so we can just run __set_page_locked() against it.
529ae9aa
NP
464 */
465static inline int add_to_page_cache(struct page *page,
466 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
467{
468 int error;
469
f45840b5 470 __set_page_locked(page);
529ae9aa
NP
471 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
472 if (unlikely(error))
f45840b5 473 __clear_page_locked(page);
529ae9aa
NP
474 return error;
475}
476
1da177e4 477#endif /* _LINUX_PAGEMAP_H */