493bfd85214ea7ffee66599b2e2617a1dfac13ed
1 #ifndef _LINUX_PAGEMAP_H
2 #define _LINUX_PAGEMAP_H
5 * Copyright 1995 Linus Torvalds
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 #include <linux/bitops.h>
15 #include <linux/hardirq.h> /* for in_interrupt() */
16 #include <linux/hugetlb_inline.h>
19 * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
20 * allocation mode 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() */
26 AS_UNEVICTABLE
= __GFP_BITS_SHIFT
+ 3, /* e.g., ramdisk, SHM_LOCK */
27 AS_BALLOON_MAP
= __GFP_BITS_SHIFT
+ 4, /* balloon page special map */
30 static inline void mapping_set_error(struct address_space
*mapping
, int error
)
32 if (unlikely(error
)) {
34 set_bit(AS_ENOSPC
, &mapping
->flags
);
36 set_bit(AS_EIO
, &mapping
->flags
);
40 static inline void mapping_set_unevictable(struct address_space
*mapping
)
42 set_bit(AS_UNEVICTABLE
, &mapping
->flags
);
45 static inline void mapping_clear_unevictable(struct address_space
*mapping
)
47 clear_bit(AS_UNEVICTABLE
, &mapping
->flags
);
50 static inline int mapping_unevictable(struct address_space
*mapping
)
53 return test_bit(AS_UNEVICTABLE
, &mapping
->flags
);
57 static inline void mapping_set_balloon(struct address_space
*mapping
)
59 set_bit(AS_BALLOON_MAP
, &mapping
->flags
);
62 static inline void mapping_clear_balloon(struct address_space
*mapping
)
64 clear_bit(AS_BALLOON_MAP
, &mapping
->flags
);
67 static inline int mapping_balloon(struct address_space
*mapping
)
69 return mapping
&& test_bit(AS_BALLOON_MAP
, &mapping
->flags
);
72 static inline gfp_t
mapping_gfp_mask(struct address_space
* mapping
)
74 return (__force gfp_t
)mapping
->flags
& __GFP_BITS_MASK
;
78 * This is non-atomic. Only to be used before the mapping is activated.
79 * Probably needs a barrier...
81 static inline void mapping_set_gfp_mask(struct address_space
*m
, gfp_t mask
)
83 m
->flags
= (m
->flags
& ~(__force
unsigned long)__GFP_BITS_MASK
) |
84 (__force
unsigned long)mask
;
88 * The page cache can done in larger chunks than
89 * one page, because it allows for more efficient
90 * throughput (it can then be mapped into user
91 * space in smaller chunks for same flexibility).
93 * Or rather, it _will_ be done in larger chunks.
95 #define PAGE_CACHE_SHIFT PAGE_SHIFT
96 #define PAGE_CACHE_SIZE PAGE_SIZE
97 #define PAGE_CACHE_MASK PAGE_MASK
98 #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
100 #define page_cache_get(page) get_page(page)
101 #define page_cache_release(page) put_page(page)
102 void release_pages(struct page
**pages
, int nr
, int cold
);
105 * speculatively take a reference to a page.
106 * If the page is free (_count == 0), then _count is untouched, and 0
107 * is returned. Otherwise, _count is incremented by 1 and 1 is returned.
109 * This function must be called inside the same rcu_read_lock() section as has
110 * been used to lookup the page in the pagecache radix-tree (or page table):
111 * this allows allocators to use a synchronize_rcu() to stabilize _count.
113 * Unless an RCU grace period has passed, the count of all pages coming out
114 * of the allocator must be considered unstable. page_count may return higher
115 * than expected, and put_page must be able to do the right thing when the
116 * page has been finished with, no matter what it is subsequently allocated
117 * for (because put_page is what is used here to drop an invalid speculative
120 * This is the interesting part of the lockless pagecache (and lockless
121 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
122 * has the following pattern:
123 * 1. find page in radix tree
124 * 2. conditionally increment refcount
125 * 3. check the page is still in pagecache (if no, goto 1)
127 * Remove-side that cares about stability of _count (eg. reclaim) has the
128 * following (with tree_lock held for write):
129 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
130 * B. remove page from pagecache
133 * There are 2 critical interleavings that matter:
134 * - 2 runs before A: in this case, A sees elevated refcount and bails out
135 * - A runs before 2: in this case, 2 sees zero refcount and retries;
136 * subsequently, B will complete and 1 will find no page, causing the
137 * lookup to return NULL.
139 * It is possible that between 1 and 2, the page is removed then the exact same
140 * page is inserted into the same position in pagecache. That's OK: the
141 * old find_get_page using tree_lock could equally have run before or after
142 * such a re-insertion, depending on order that locks are granted.
144 * Lookups racing against pagecache insertion isn't a big problem: either 1
145 * will find the page or it will not. Likewise, the old find_get_page could run
146 * either before the insertion or afterwards, depending on timing.
148 static inline int page_cache_get_speculative(struct page
*page
)
150 VM_BUG_ON(in_interrupt());
152 #ifdef CONFIG_TINY_RCU
153 # ifdef CONFIG_PREEMPT_COUNT
154 VM_BUG_ON(!in_atomic());
157 * Preempt must be disabled here - we rely on rcu_read_lock doing
160 * Pagecache won't be truncated from interrupt context, so if we have
161 * found a page in the radix tree here, we have pinned its refcount by
162 * disabling preempt, and hence no need for the "speculative get" that
165 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
166 atomic_inc(&page
->_count
);
169 if (unlikely(!get_page_unless_zero(page
))) {
171 * Either the page has been freed, or will be freed.
172 * In either case, retry here and the caller should
173 * do the right thing (see comments above).
178 VM_BUG_ON_PAGE(PageTail(page
), page
);
184 * Same as above, but add instead of inc (could just be merged)
186 static inline int page_cache_add_speculative(struct page
*page
, int count
)
188 VM_BUG_ON(in_interrupt());
190 #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
191 # ifdef CONFIG_PREEMPT_COUNT
192 VM_BUG_ON(!in_atomic());
194 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
195 atomic_add(count
, &page
->_count
);
198 if (unlikely(!atomic_add_unless(&page
->_count
, count
, 0)))
201 VM_BUG_ON_PAGE(PageCompound(page
) && page
!= compound_head(page
), page
);
206 static inline int page_freeze_refs(struct page
*page
, int count
)
208 return likely(atomic_cmpxchg(&page
->_count
, count
, 0) == count
);
211 static inline void page_unfreeze_refs(struct page
*page
, int count
)
213 VM_BUG_ON_PAGE(page_count(page
) != 0, page
);
214 VM_BUG_ON(count
== 0);
216 atomic_set(&page
->_count
, count
);
220 extern struct page
*__page_cache_alloc(gfp_t gfp
);
222 static inline struct page
*__page_cache_alloc(gfp_t gfp
)
224 return alloc_pages(gfp
, 0);
228 static inline struct page
*page_cache_alloc(struct address_space
*x
)
230 return __page_cache_alloc(mapping_gfp_mask(x
));
233 static inline struct page
*page_cache_alloc_cold(struct address_space
*x
)
235 return __page_cache_alloc(mapping_gfp_mask(x
)|__GFP_COLD
);
238 static inline struct page
*page_cache_alloc_readahead(struct address_space
*x
)
240 return __page_cache_alloc(mapping_gfp_mask(x
) |
241 __GFP_COLD
| __GFP_NORETRY
| __GFP_NOWARN
);
244 typedef int filler_t(void *, struct page
*);
246 pgoff_t
page_cache_next_hole(struct address_space
*mapping
,
247 pgoff_t index
, unsigned long max_scan
);
248 pgoff_t
page_cache_prev_hole(struct address_space
*mapping
,
249 pgoff_t index
, unsigned long max_scan
);
251 struct page
*find_get_entry(struct address_space
*mapping
, pgoff_t offset
);
252 struct page
*find_get_page(struct address_space
*mapping
, pgoff_t offset
);
253 struct page
*find_lock_entry(struct address_space
*mapping
, pgoff_t offset
);
254 struct page
*find_lock_page(struct address_space
*mapping
, pgoff_t offset
);
255 struct page
*find_or_create_page(struct address_space
*mapping
, pgoff_t index
,
257 unsigned find_get_entries(struct address_space
*mapping
, pgoff_t start
,
258 unsigned int nr_entries
, struct page
**entries
,
260 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
261 unsigned int nr_pages
, struct page
**pages
);
262 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t start
,
263 unsigned int nr_pages
, struct page
**pages
);
264 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
265 int tag
, unsigned int nr_pages
, struct page
**pages
);
267 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
268 pgoff_t index
, unsigned flags
);
271 * Returns locked page at given index in given cache, creating it if needed.
273 static inline struct page
*grab_cache_page(struct address_space
*mapping
,
276 return find_or_create_page(mapping
, index
, mapping_gfp_mask(mapping
));
279 extern struct page
* grab_cache_page_nowait(struct address_space
*mapping
,
281 extern struct page
* read_cache_page_async(struct address_space
*mapping
,
282 pgoff_t index
, filler_t
*filler
, void *data
);
283 extern struct page
* read_cache_page(struct address_space
*mapping
,
284 pgoff_t index
, filler_t
*filler
, void *data
);
285 extern struct page
* read_cache_page_gfp(struct address_space
*mapping
,
286 pgoff_t index
, gfp_t gfp_mask
);
287 extern int read_cache_pages(struct address_space
*mapping
,
288 struct list_head
*pages
, filler_t
*filler
, void *data
);
290 static inline struct page
*read_mapping_page_async(
291 struct address_space
*mapping
,
292 pgoff_t index
, void *data
)
294 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
295 return read_cache_page_async(mapping
, index
, filler
, data
);
298 static inline struct page
*read_mapping_page(struct address_space
*mapping
,
299 pgoff_t index
, void *data
)
301 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
302 return read_cache_page(mapping
, index
, filler
, data
);
306 * Return byte-offset into filesystem object for page.
308 static inline loff_t
page_offset(struct page
*page
)
310 return ((loff_t
)page
->index
) << PAGE_CACHE_SHIFT
;
313 static inline loff_t
page_file_offset(struct page
*page
)
315 return ((loff_t
)page_file_index(page
)) << PAGE_CACHE_SHIFT
;
318 extern pgoff_t
linear_hugepage_index(struct vm_area_struct
*vma
,
319 unsigned long address
);
321 static inline pgoff_t
linear_page_index(struct vm_area_struct
*vma
,
322 unsigned long address
)
325 if (unlikely(is_vm_hugetlb_page(vma
)))
326 return linear_hugepage_index(vma
, address
);
327 pgoff
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
328 pgoff
+= vma
->vm_pgoff
;
329 return pgoff
>> (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
332 extern void __lock_page(struct page
*page
);
333 extern int __lock_page_killable(struct page
*page
);
334 extern int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
336 extern void unlock_page(struct page
*page
);
338 static inline void __set_page_locked(struct page
*page
)
340 __set_bit(PG_locked
, &page
->flags
);
343 static inline void __clear_page_locked(struct page
*page
)
345 __clear_bit(PG_locked
, &page
->flags
);
348 static inline int trylock_page(struct page
*page
)
350 return (likely(!test_and_set_bit_lock(PG_locked
, &page
->flags
)));
354 * lock_page may only be called if we have the page's inode pinned.
356 static inline void lock_page(struct page
*page
)
359 if (!trylock_page(page
))
364 * lock_page_killable is like lock_page but can be interrupted by fatal
365 * signals. It returns 0 if it locked the page and -EINTR if it was
366 * killed while waiting.
368 static inline int lock_page_killable(struct page
*page
)
371 if (!trylock_page(page
))
372 return __lock_page_killable(page
);
377 * lock_page_or_retry - Lock the page, unless this would block and the
378 * caller indicated that it can handle a retry.
380 static inline int lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
384 return trylock_page(page
) || __lock_page_or_retry(page
, mm
, flags
);
388 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
389 * Never use this directly!
391 extern void wait_on_page_bit(struct page
*page
, int bit_nr
);
393 extern int wait_on_page_bit_killable(struct page
*page
, int bit_nr
);
395 static inline int wait_on_page_locked_killable(struct page
*page
)
397 if (PageLocked(page
))
398 return wait_on_page_bit_killable(page
, PG_locked
);
403 * Wait for a page to be unlocked.
405 * This must be called with the caller "holding" the page,
406 * ie with increased "page->count" so that the page won't
407 * go away during the wait..
409 static inline void wait_on_page_locked(struct page
*page
)
411 if (PageLocked(page
))
412 wait_on_page_bit(page
, PG_locked
);
416 * Wait for a page to complete writeback
418 static inline void wait_on_page_writeback(struct page
*page
)
420 if (PageWriteback(page
))
421 wait_on_page_bit(page
, PG_writeback
);
424 extern void end_page_writeback(struct page
*page
);
425 void wait_for_stable_page(struct page
*page
);
428 * Add an arbitrary waiter to a page's wait queue
430 extern void add_page_wait_queue(struct page
*page
, wait_queue_t
*waiter
);
433 * Fault a userspace page into pagetables. Return non-zero on a fault.
435 * This assumes that two userspace pages are always sufficient. That's
436 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
438 static inline int fault_in_pages_writeable(char __user
*uaddr
, int size
)
442 if (unlikely(size
== 0))
446 * Writing zeroes into userspace here is OK, because we know that if
447 * the zero gets there, we'll be overwriting it.
449 ret
= __put_user(0, uaddr
);
451 char __user
*end
= uaddr
+ size
- 1;
454 * If the page was already mapped, this will get a cache miss
455 * for sure, so try to avoid doing it.
457 if (((unsigned long)uaddr
& PAGE_MASK
) !=
458 ((unsigned long)end
& PAGE_MASK
))
459 ret
= __put_user(0, end
);
464 static inline int fault_in_pages_readable(const char __user
*uaddr
, int size
)
469 if (unlikely(size
== 0))
472 ret
= __get_user(c
, uaddr
);
474 const char __user
*end
= uaddr
+ size
- 1;
476 if (((unsigned long)uaddr
& PAGE_MASK
) !=
477 ((unsigned long)end
& PAGE_MASK
)) {
478 ret
= __get_user(c
, end
);
486 * Multipage variants of the above prefault helpers, useful if more than
487 * PAGE_SIZE of data needs to be prefaulted. These are separate from the above
488 * functions (which only handle up to PAGE_SIZE) to avoid clobbering the
489 * filemap.c hotpaths.
491 static inline int fault_in_multipages_writeable(char __user
*uaddr
, int size
)
494 char __user
*end
= uaddr
+ size
- 1;
496 if (unlikely(size
== 0))
500 * Writing zeroes into userspace here is OK, because we know that if
501 * the zero gets there, we'll be overwriting it.
503 while (uaddr
<= end
) {
504 ret
= __put_user(0, uaddr
);
510 /* Check whether the range spilled into the next page. */
511 if (((unsigned long)uaddr
& PAGE_MASK
) ==
512 ((unsigned long)end
& PAGE_MASK
))
513 ret
= __put_user(0, end
);
518 static inline int fault_in_multipages_readable(const char __user
*uaddr
,
523 const char __user
*end
= uaddr
+ size
- 1;
525 if (unlikely(size
== 0))
528 while (uaddr
<= end
) {
529 ret
= __get_user(c
, uaddr
);
535 /* Check whether the range spilled into the next page. */
536 if (((unsigned long)uaddr
& PAGE_MASK
) ==
537 ((unsigned long)end
& PAGE_MASK
)) {
538 ret
= __get_user(c
, end
);
545 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
546 pgoff_t index
, gfp_t gfp_mask
);
547 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
548 pgoff_t index
, gfp_t gfp_mask
);
549 extern void delete_from_page_cache(struct page
*page
);
550 extern void __delete_from_page_cache(struct page
*page
);
551 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
);
554 * Like add_to_page_cache_locked, but used to add newly allocated pages:
555 * the page is new, so we can just run __set_page_locked() against it.
557 static inline int add_to_page_cache(struct page
*page
,
558 struct address_space
*mapping
, pgoff_t offset
, gfp_t gfp_mask
)
562 __set_page_locked(page
);
563 error
= add_to_page_cache_locked(page
, mapping
, offset
, gfp_mask
);
565 __clear_page_locked(page
);
569 #endif /* _LINUX_PAGEMAP_H */
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