ff43253f568a9395dc7c852946460e43917c8ac3
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 */
28 AS_EXITING
= __GFP_BITS_SHIFT
+ 5, /* final truncate in progress */
31 static inline void mapping_set_error(struct address_space
*mapping
, int error
)
33 if (unlikely(error
)) {
35 set_bit(AS_ENOSPC
, &mapping
->flags
);
37 set_bit(AS_EIO
, &mapping
->flags
);
41 static inline void mapping_set_unevictable(struct address_space
*mapping
)
43 set_bit(AS_UNEVICTABLE
, &mapping
->flags
);
46 static inline void mapping_clear_unevictable(struct address_space
*mapping
)
48 clear_bit(AS_UNEVICTABLE
, &mapping
->flags
);
51 static inline int mapping_unevictable(struct address_space
*mapping
)
54 return test_bit(AS_UNEVICTABLE
, &mapping
->flags
);
58 static inline void mapping_set_balloon(struct address_space
*mapping
)
60 set_bit(AS_BALLOON_MAP
, &mapping
->flags
);
63 static inline void mapping_clear_balloon(struct address_space
*mapping
)
65 clear_bit(AS_BALLOON_MAP
, &mapping
->flags
);
68 static inline int mapping_balloon(struct address_space
*mapping
)
70 return mapping
&& test_bit(AS_BALLOON_MAP
, &mapping
->flags
);
73 static inline void mapping_set_exiting(struct address_space
*mapping
)
75 set_bit(AS_EXITING
, &mapping
->flags
);
78 static inline int mapping_exiting(struct address_space
*mapping
)
80 return test_bit(AS_EXITING
, &mapping
->flags
);
83 static inline gfp_t
mapping_gfp_mask(struct address_space
* mapping
)
85 return (__force gfp_t
)mapping
->flags
& __GFP_BITS_MASK
;
89 * This is non-atomic. Only to be used before the mapping is activated.
90 * Probably needs a barrier...
92 static inline void mapping_set_gfp_mask(struct address_space
*m
, gfp_t mask
)
94 m
->flags
= (m
->flags
& ~(__force
unsigned long)__GFP_BITS_MASK
) |
95 (__force
unsigned long)mask
;
99 * The page cache can done in larger chunks than
100 * one page, because it allows for more efficient
101 * throughput (it can then be mapped into user
102 * space in smaller chunks for same flexibility).
104 * Or rather, it _will_ be done in larger chunks.
106 #define PAGE_CACHE_SHIFT PAGE_SHIFT
107 #define PAGE_CACHE_SIZE PAGE_SIZE
108 #define PAGE_CACHE_MASK PAGE_MASK
109 #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
111 #define page_cache_get(page) get_page(page)
112 #define page_cache_release(page) put_page(page)
113 void release_pages(struct page
**pages
, int nr
, int cold
);
116 * speculatively take a reference to a page.
117 * If the page is free (_count == 0), then _count is untouched, and 0
118 * is returned. Otherwise, _count is incremented by 1 and 1 is returned.
120 * This function must be called inside the same rcu_read_lock() section as has
121 * been used to lookup the page in the pagecache radix-tree (or page table):
122 * this allows allocators to use a synchronize_rcu() to stabilize _count.
124 * Unless an RCU grace period has passed, the count of all pages coming out
125 * of the allocator must be considered unstable. page_count may return higher
126 * than expected, and put_page must be able to do the right thing when the
127 * page has been finished with, no matter what it is subsequently allocated
128 * for (because put_page is what is used here to drop an invalid speculative
131 * This is the interesting part of the lockless pagecache (and lockless
132 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
133 * has the following pattern:
134 * 1. find page in radix tree
135 * 2. conditionally increment refcount
136 * 3. check the page is still in pagecache (if no, goto 1)
138 * Remove-side that cares about stability of _count (eg. reclaim) has the
139 * following (with tree_lock held for write):
140 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
141 * B. remove page from pagecache
144 * There are 2 critical interleavings that matter:
145 * - 2 runs before A: in this case, A sees elevated refcount and bails out
146 * - A runs before 2: in this case, 2 sees zero refcount and retries;
147 * subsequently, B will complete and 1 will find no page, causing the
148 * lookup to return NULL.
150 * It is possible that between 1 and 2, the page is removed then the exact same
151 * page is inserted into the same position in pagecache. That's OK: the
152 * old find_get_page using tree_lock could equally have run before or after
153 * such a re-insertion, depending on order that locks are granted.
155 * Lookups racing against pagecache insertion isn't a big problem: either 1
156 * will find the page or it will not. Likewise, the old find_get_page could run
157 * either before the insertion or afterwards, depending on timing.
159 static inline int page_cache_get_speculative(struct page
*page
)
161 VM_BUG_ON(in_interrupt());
163 #ifdef CONFIG_TINY_RCU
164 # ifdef CONFIG_PREEMPT_COUNT
165 VM_BUG_ON(!in_atomic());
168 * Preempt must be disabled here - we rely on rcu_read_lock doing
171 * Pagecache won't be truncated from interrupt context, so if we have
172 * found a page in the radix tree here, we have pinned its refcount by
173 * disabling preempt, and hence no need for the "speculative get" that
176 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
177 atomic_inc(&page
->_count
);
180 if (unlikely(!get_page_unless_zero(page
))) {
182 * Either the page has been freed, or will be freed.
183 * In either case, retry here and the caller should
184 * do the right thing (see comments above).
189 VM_BUG_ON_PAGE(PageTail(page
), page
);
195 * Same as above, but add instead of inc (could just be merged)
197 static inline int page_cache_add_speculative(struct page
*page
, int count
)
199 VM_BUG_ON(in_interrupt());
201 #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
202 # ifdef CONFIG_PREEMPT_COUNT
203 VM_BUG_ON(!in_atomic());
205 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
206 atomic_add(count
, &page
->_count
);
209 if (unlikely(!atomic_add_unless(&page
->_count
, count
, 0)))
212 VM_BUG_ON_PAGE(PageCompound(page
) && page
!= compound_head(page
), page
);
217 static inline int page_freeze_refs(struct page
*page
, int count
)
219 return likely(atomic_cmpxchg(&page
->_count
, count
, 0) == count
);
222 static inline void page_unfreeze_refs(struct page
*page
, int count
)
224 VM_BUG_ON_PAGE(page_count(page
) != 0, page
);
225 VM_BUG_ON(count
== 0);
227 atomic_set(&page
->_count
, count
);
231 extern struct page
*__page_cache_alloc(gfp_t gfp
);
233 static inline struct page
*__page_cache_alloc(gfp_t gfp
)
235 return alloc_pages(gfp
, 0);
239 static inline struct page
*page_cache_alloc(struct address_space
*x
)
241 return __page_cache_alloc(mapping_gfp_mask(x
));
244 static inline struct page
*page_cache_alloc_cold(struct address_space
*x
)
246 return __page_cache_alloc(mapping_gfp_mask(x
)|__GFP_COLD
);
249 static inline struct page
*page_cache_alloc_readahead(struct address_space
*x
)
251 return __page_cache_alloc(mapping_gfp_mask(x
) |
252 __GFP_COLD
| __GFP_NORETRY
| __GFP_NOWARN
);
255 typedef int filler_t(void *, struct page
*);
257 pgoff_t
page_cache_next_hole(struct address_space
*mapping
,
258 pgoff_t index
, unsigned long max_scan
);
259 pgoff_t
page_cache_prev_hole(struct address_space
*mapping
,
260 pgoff_t index
, unsigned long max_scan
);
262 struct page
*find_get_entry(struct address_space
*mapping
, pgoff_t offset
);
263 struct page
*find_get_page(struct address_space
*mapping
, pgoff_t offset
);
264 struct page
*find_lock_entry(struct address_space
*mapping
, pgoff_t offset
);
265 struct page
*find_lock_page(struct address_space
*mapping
, pgoff_t offset
);
266 struct page
*find_or_create_page(struct address_space
*mapping
, pgoff_t index
,
268 unsigned find_get_entries(struct address_space
*mapping
, pgoff_t start
,
269 unsigned int nr_entries
, struct page
**entries
,
271 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
272 unsigned int nr_pages
, struct page
**pages
);
273 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t start
,
274 unsigned int nr_pages
, struct page
**pages
);
275 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
276 int tag
, unsigned int nr_pages
, struct page
**pages
);
278 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
279 pgoff_t index
, unsigned flags
);
282 * Returns locked page at given index in given cache, creating it if needed.
284 static inline struct page
*grab_cache_page(struct address_space
*mapping
,
287 return find_or_create_page(mapping
, index
, mapping_gfp_mask(mapping
));
290 extern struct page
* grab_cache_page_nowait(struct address_space
*mapping
,
292 extern struct page
* read_cache_page_async(struct address_space
*mapping
,
293 pgoff_t index
, filler_t
*filler
, void *data
);
294 extern struct page
* read_cache_page(struct address_space
*mapping
,
295 pgoff_t index
, filler_t
*filler
, void *data
);
296 extern struct page
* read_cache_page_gfp(struct address_space
*mapping
,
297 pgoff_t index
, gfp_t gfp_mask
);
298 extern int read_cache_pages(struct address_space
*mapping
,
299 struct list_head
*pages
, filler_t
*filler
, void *data
);
301 static inline struct page
*read_mapping_page_async(
302 struct address_space
*mapping
,
303 pgoff_t index
, void *data
)
305 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
306 return read_cache_page_async(mapping
, index
, filler
, data
);
309 static inline struct page
*read_mapping_page(struct address_space
*mapping
,
310 pgoff_t index
, void *data
)
312 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
313 return read_cache_page(mapping
, index
, filler
, data
);
317 * Return byte-offset into filesystem object for page.
319 static inline loff_t
page_offset(struct page
*page
)
321 return ((loff_t
)page
->index
) << PAGE_CACHE_SHIFT
;
324 static inline loff_t
page_file_offset(struct page
*page
)
326 return ((loff_t
)page_file_index(page
)) << PAGE_CACHE_SHIFT
;
329 extern pgoff_t
linear_hugepage_index(struct vm_area_struct
*vma
,
330 unsigned long address
);
332 static inline pgoff_t
linear_page_index(struct vm_area_struct
*vma
,
333 unsigned long address
)
336 if (unlikely(is_vm_hugetlb_page(vma
)))
337 return linear_hugepage_index(vma
, address
);
338 pgoff
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
339 pgoff
+= vma
->vm_pgoff
;
340 return pgoff
>> (PAGE_CACHE_SHIFT
- PAGE_SHIFT
);
343 extern void __lock_page(struct page
*page
);
344 extern int __lock_page_killable(struct page
*page
);
345 extern int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
347 extern void unlock_page(struct page
*page
);
349 static inline void __set_page_locked(struct page
*page
)
351 __set_bit(PG_locked
, &page
->flags
);
354 static inline void __clear_page_locked(struct page
*page
)
356 __clear_bit(PG_locked
, &page
->flags
);
359 static inline int trylock_page(struct page
*page
)
361 return (likely(!test_and_set_bit_lock(PG_locked
, &page
->flags
)));
365 * lock_page may only be called if we have the page's inode pinned.
367 static inline void lock_page(struct page
*page
)
370 if (!trylock_page(page
))
375 * lock_page_killable is like lock_page but can be interrupted by fatal
376 * signals. It returns 0 if it locked the page and -EINTR if it was
377 * killed while waiting.
379 static inline int lock_page_killable(struct page
*page
)
382 if (!trylock_page(page
))
383 return __lock_page_killable(page
);
388 * lock_page_or_retry - Lock the page, unless this would block and the
389 * caller indicated that it can handle a retry.
391 static inline int lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
395 return trylock_page(page
) || __lock_page_or_retry(page
, mm
, flags
);
399 * This is exported only for wait_on_page_locked/wait_on_page_writeback.
400 * Never use this directly!
402 extern void wait_on_page_bit(struct page
*page
, int bit_nr
);
404 extern int wait_on_page_bit_killable(struct page
*page
, int bit_nr
);
406 static inline int wait_on_page_locked_killable(struct page
*page
)
408 if (PageLocked(page
))
409 return wait_on_page_bit_killable(page
, PG_locked
);
414 * Wait for a page to be unlocked.
416 * This must be called with the caller "holding" the page,
417 * ie with increased "page->count" so that the page won't
418 * go away during the wait..
420 static inline void wait_on_page_locked(struct page
*page
)
422 if (PageLocked(page
))
423 wait_on_page_bit(page
, PG_locked
);
427 * Wait for a page to complete writeback
429 static inline void wait_on_page_writeback(struct page
*page
)
431 if (PageWriteback(page
))
432 wait_on_page_bit(page
, PG_writeback
);
435 extern void end_page_writeback(struct page
*page
);
436 void wait_for_stable_page(struct page
*page
);
439 * Add an arbitrary waiter to a page's wait queue
441 extern void add_page_wait_queue(struct page
*page
, wait_queue_t
*waiter
);
444 * Fault a userspace page into pagetables. Return non-zero on a fault.
446 * This assumes that two userspace pages are always sufficient. That's
447 * not true if PAGE_CACHE_SIZE > PAGE_SIZE.
449 static inline int fault_in_pages_writeable(char __user
*uaddr
, int size
)
453 if (unlikely(size
== 0))
457 * Writing zeroes into userspace here is OK, because we know that if
458 * the zero gets there, we'll be overwriting it.
460 ret
= __put_user(0, uaddr
);
462 char __user
*end
= uaddr
+ size
- 1;
465 * If the page was already mapped, this will get a cache miss
466 * for sure, so try to avoid doing it.
468 if (((unsigned long)uaddr
& PAGE_MASK
) !=
469 ((unsigned long)end
& PAGE_MASK
))
470 ret
= __put_user(0, end
);
475 static inline int fault_in_pages_readable(const char __user
*uaddr
, int size
)
480 if (unlikely(size
== 0))
483 ret
= __get_user(c
, uaddr
);
485 const char __user
*end
= uaddr
+ size
- 1;
487 if (((unsigned long)uaddr
& PAGE_MASK
) !=
488 ((unsigned long)end
& PAGE_MASK
)) {
489 ret
= __get_user(c
, end
);
497 * Multipage variants of the above prefault helpers, useful if more than
498 * PAGE_SIZE of data needs to be prefaulted. These are separate from the above
499 * functions (which only handle up to PAGE_SIZE) to avoid clobbering the
500 * filemap.c hotpaths.
502 static inline int fault_in_multipages_writeable(char __user
*uaddr
, int size
)
505 char __user
*end
= uaddr
+ size
- 1;
507 if (unlikely(size
== 0))
511 * Writing zeroes into userspace here is OK, because we know that if
512 * the zero gets there, we'll be overwriting it.
514 while (uaddr
<= end
) {
515 ret
= __put_user(0, uaddr
);
521 /* Check whether the range spilled into the next page. */
522 if (((unsigned long)uaddr
& PAGE_MASK
) ==
523 ((unsigned long)end
& PAGE_MASK
))
524 ret
= __put_user(0, end
);
529 static inline int fault_in_multipages_readable(const char __user
*uaddr
,
534 const char __user
*end
= uaddr
+ size
- 1;
536 if (unlikely(size
== 0))
539 while (uaddr
<= end
) {
540 ret
= __get_user(c
, uaddr
);
546 /* Check whether the range spilled into the next page. */
547 if (((unsigned long)uaddr
& PAGE_MASK
) ==
548 ((unsigned long)end
& PAGE_MASK
)) {
549 ret
= __get_user(c
, end
);
556 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
557 pgoff_t index
, gfp_t gfp_mask
);
558 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
559 pgoff_t index
, gfp_t gfp_mask
);
560 extern void delete_from_page_cache(struct page
*page
);
561 extern void __delete_from_page_cache(struct page
*page
, void *shadow
);
562 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
);
565 * Like add_to_page_cache_locked, but used to add newly allocated pages:
566 * the page is new, so we can just run __set_page_locked() against it.
568 static inline int add_to_page_cache(struct page
*page
,
569 struct address_space
*mapping
, pgoff_t offset
, gfp_t gfp_mask
)
573 __set_page_locked(page
);
574 error
= add_to_page_cache_locked(page
, mapping
, offset
, gfp_mask
);
576 __clear_page_locked(page
);
580 #endif /* _LINUX_PAGEMAP_H */
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