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git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - include/linux/pagemap.h
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_EXITING
= __GFP_BITS_SHIFT
+ 4, /* final truncate in progress */
28 /* writeback related tags are not used */
29 AS_NO_WRITEBACK_TAGS
= __GFP_BITS_SHIFT
+ 5,
32 static inline void mapping_set_error(struct address_space
*mapping
, int error
)
34 if (unlikely(error
)) {
36 set_bit(AS_ENOSPC
, &mapping
->flags
);
38 set_bit(AS_EIO
, &mapping
->flags
);
42 static inline void mapping_set_unevictable(struct address_space
*mapping
)
44 set_bit(AS_UNEVICTABLE
, &mapping
->flags
);
47 static inline void mapping_clear_unevictable(struct address_space
*mapping
)
49 clear_bit(AS_UNEVICTABLE
, &mapping
->flags
);
52 static inline int mapping_unevictable(struct address_space
*mapping
)
55 return test_bit(AS_UNEVICTABLE
, &mapping
->flags
);
59 static inline void mapping_set_exiting(struct address_space
*mapping
)
61 set_bit(AS_EXITING
, &mapping
->flags
);
64 static inline int mapping_exiting(struct address_space
*mapping
)
66 return test_bit(AS_EXITING
, &mapping
->flags
);
69 static inline void mapping_set_no_writeback_tags(struct address_space
*mapping
)
71 set_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
74 static inline int mapping_use_writeback_tags(struct address_space
*mapping
)
76 return !test_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
79 static inline gfp_t
mapping_gfp_mask(struct address_space
* mapping
)
81 return (__force gfp_t
)mapping
->flags
& __GFP_BITS_MASK
;
84 /* Restricts the given gfp_mask to what the mapping allows. */
85 static inline gfp_t
mapping_gfp_constraint(struct address_space
*mapping
,
88 return mapping_gfp_mask(mapping
) & gfp_mask
;
92 * This is non-atomic. Only to be used before the mapping is activated.
93 * Probably needs a barrier...
95 static inline void mapping_set_gfp_mask(struct address_space
*m
, gfp_t mask
)
97 m
->flags
= (m
->flags
& ~(__force
unsigned long)__GFP_BITS_MASK
) |
98 (__force
unsigned long)mask
;
101 void release_pages(struct page
**pages
, int nr
, bool cold
);
104 * speculatively take a reference to a page.
105 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
106 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
108 * This function must be called inside the same rcu_read_lock() section as has
109 * been used to lookup the page in the pagecache radix-tree (or page table):
110 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
112 * Unless an RCU grace period has passed, the count of all pages coming out
113 * of the allocator must be considered unstable. page_count may return higher
114 * than expected, and put_page must be able to do the right thing when the
115 * page has been finished with, no matter what it is subsequently allocated
116 * for (because put_page is what is used here to drop an invalid speculative
119 * This is the interesting part of the lockless pagecache (and lockless
120 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
121 * has the following pattern:
122 * 1. find page in radix tree
123 * 2. conditionally increment refcount
124 * 3. check the page is still in pagecache (if no, goto 1)
126 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
127 * following (with tree_lock held for write):
128 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
129 * B. remove page from pagecache
132 * There are 2 critical interleavings that matter:
133 * - 2 runs before A: in this case, A sees elevated refcount and bails out
134 * - A runs before 2: in this case, 2 sees zero refcount and retries;
135 * subsequently, B will complete and 1 will find no page, causing the
136 * lookup to return NULL.
138 * It is possible that between 1 and 2, the page is removed then the exact same
139 * page is inserted into the same position in pagecache. That's OK: the
140 * old find_get_page using tree_lock could equally have run before or after
141 * such a re-insertion, depending on order that locks are granted.
143 * Lookups racing against pagecache insertion isn't a big problem: either 1
144 * will find the page or it will not. Likewise, the old find_get_page could run
145 * either before the insertion or afterwards, depending on timing.
147 static inline int page_cache_get_speculative(struct page
*page
)
149 VM_BUG_ON(in_interrupt());
151 #ifdef CONFIG_TINY_RCU
152 # ifdef CONFIG_PREEMPT_COUNT
153 VM_BUG_ON(!in_atomic());
156 * Preempt must be disabled here - we rely on rcu_read_lock doing
159 * Pagecache won't be truncated from interrupt context, so if we have
160 * found a page in the radix tree here, we have pinned its refcount by
161 * disabling preempt, and hence no need for the "speculative get" that
164 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
168 if (unlikely(!get_page_unless_zero(page
))) {
170 * Either the page has been freed, or will be freed.
171 * In either case, retry here and the caller should
172 * do the right thing (see comments above).
177 VM_BUG_ON_PAGE(PageTail(page
), page
);
183 * Same as above, but add instead of inc (could just be merged)
185 static inline int page_cache_add_speculative(struct page
*page
, int count
)
187 VM_BUG_ON(in_interrupt());
189 #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
190 # ifdef CONFIG_PREEMPT_COUNT
191 VM_BUG_ON(!in_atomic());
193 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
194 page_ref_add(page
, count
);
197 if (unlikely(!page_ref_add_unless(page
, count
, 0)))
200 VM_BUG_ON_PAGE(PageCompound(page
) && page
!= compound_head(page
), page
);
206 extern struct page
*__page_cache_alloc(gfp_t gfp
);
208 static inline struct page
*__page_cache_alloc(gfp_t gfp
)
210 return alloc_pages(gfp
, 0);
214 static inline struct page
*page_cache_alloc(struct address_space
*x
)
216 return __page_cache_alloc(mapping_gfp_mask(x
));
219 static inline struct page
*page_cache_alloc_cold(struct address_space
*x
)
221 return __page_cache_alloc(mapping_gfp_mask(x
)|__GFP_COLD
);
224 static inline gfp_t
readahead_gfp_mask(struct address_space
*x
)
226 return mapping_gfp_mask(x
) |
227 __GFP_COLD
| __GFP_NORETRY
| __GFP_NOWARN
;
230 typedef int filler_t(void *, struct page
*);
232 pgoff_t
page_cache_next_hole(struct address_space
*mapping
,
233 pgoff_t index
, unsigned long max_scan
);
234 pgoff_t
page_cache_prev_hole(struct address_space
*mapping
,
235 pgoff_t index
, unsigned long max_scan
);
237 #define FGP_ACCESSED 0x00000001
238 #define FGP_LOCK 0x00000002
239 #define FGP_CREAT 0x00000004
240 #define FGP_WRITE 0x00000008
241 #define FGP_NOFS 0x00000010
242 #define FGP_NOWAIT 0x00000020
244 struct page
*pagecache_get_page(struct address_space
*mapping
, pgoff_t offset
,
245 int fgp_flags
, gfp_t cache_gfp_mask
);
248 * find_get_page - find and get a page reference
249 * @mapping: the address_space to search
250 * @offset: the page index
252 * Looks up the page cache slot at @mapping & @offset. If there is a
253 * page cache page, it is returned with an increased refcount.
255 * Otherwise, %NULL is returned.
257 static inline struct page
*find_get_page(struct address_space
*mapping
,
260 return pagecache_get_page(mapping
, offset
, 0, 0);
263 static inline struct page
*find_get_page_flags(struct address_space
*mapping
,
264 pgoff_t offset
, int fgp_flags
)
266 return pagecache_get_page(mapping
, offset
, fgp_flags
, 0);
270 * find_lock_page - locate, pin and lock a pagecache page
271 * pagecache_get_page - find and get a page reference
272 * @mapping: the address_space to search
273 * @offset: the page index
275 * Looks up the page cache slot at @mapping & @offset. If there is a
276 * page cache page, it is returned locked and with an increased
279 * Otherwise, %NULL is returned.
281 * find_lock_page() may sleep.
283 static inline struct page
*find_lock_page(struct address_space
*mapping
,
286 return pagecache_get_page(mapping
, offset
, FGP_LOCK
, 0);
290 * find_or_create_page - locate or add a pagecache page
291 * @mapping: the page's address_space
292 * @index: the page's index into the mapping
293 * @gfp_mask: page allocation mode
295 * Looks up the page cache slot at @mapping & @offset. If there is a
296 * page cache page, it is returned locked and with an increased
299 * If the page is not present, a new page is allocated using @gfp_mask
300 * and added to the page cache and the VM's LRU list. The page is
301 * returned locked and with an increased refcount.
303 * On memory exhaustion, %NULL is returned.
305 * find_or_create_page() may sleep, even if @gfp_flags specifies an
308 static inline struct page
*find_or_create_page(struct address_space
*mapping
,
309 pgoff_t offset
, gfp_t gfp_mask
)
311 return pagecache_get_page(mapping
, offset
,
312 FGP_LOCK
|FGP_ACCESSED
|FGP_CREAT
,
317 * grab_cache_page_nowait - returns locked page at given index in given cache
318 * @mapping: target address_space
319 * @index: the page index
321 * Same as grab_cache_page(), but do not wait if the page is unavailable.
322 * This is intended for speculative data generators, where the data can
323 * be regenerated if the page couldn't be grabbed. This routine should
324 * be safe to call while holding the lock for another page.
326 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
327 * and deadlock against the caller's locked page.
329 static inline struct page
*grab_cache_page_nowait(struct address_space
*mapping
,
332 return pagecache_get_page(mapping
, index
,
333 FGP_LOCK
|FGP_CREAT
|FGP_NOFS
|FGP_NOWAIT
,
334 mapping_gfp_mask(mapping
));
337 struct page
*find_get_entry(struct address_space
*mapping
, pgoff_t offset
);
338 struct page
*find_lock_entry(struct address_space
*mapping
, pgoff_t offset
);
339 unsigned find_get_entries(struct address_space
*mapping
, pgoff_t start
,
340 unsigned int nr_entries
, struct page
**entries
,
342 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
343 unsigned int nr_pages
, struct page
**pages
);
344 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t start
,
345 unsigned int nr_pages
, struct page
**pages
);
346 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
347 int tag
, unsigned int nr_pages
, struct page
**pages
);
348 unsigned find_get_entries_tag(struct address_space
*mapping
, pgoff_t start
,
349 int tag
, unsigned int nr_entries
,
350 struct page
**entries
, pgoff_t
*indices
);
352 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
353 pgoff_t index
, unsigned flags
);
356 * Returns locked page at given index in given cache, creating it if needed.
358 static inline struct page
*grab_cache_page(struct address_space
*mapping
,
361 return find_or_create_page(mapping
, index
, mapping_gfp_mask(mapping
));
364 extern struct page
* read_cache_page(struct address_space
*mapping
,
365 pgoff_t index
, filler_t
*filler
, void *data
);
366 extern struct page
* read_cache_page_gfp(struct address_space
*mapping
,
367 pgoff_t index
, gfp_t gfp_mask
);
368 extern int read_cache_pages(struct address_space
*mapping
,
369 struct list_head
*pages
, filler_t
*filler
, void *data
);
371 static inline struct page
*read_mapping_page(struct address_space
*mapping
,
372 pgoff_t index
, void *data
)
374 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
375 return read_cache_page(mapping
, index
, filler
, data
);
379 * Get the offset in PAGE_SIZE.
380 * (TODO: hugepage should have ->index in PAGE_SIZE)
382 static inline pgoff_t
page_to_pgoff(struct page
*page
)
386 if (unlikely(PageHeadHuge(page
)))
387 return page
->index
<< compound_order(page
);
389 if (likely(!PageTransTail(page
)))
393 * We don't initialize ->index for tail pages: calculate based on
396 pgoff
= compound_head(page
)->index
;
397 pgoff
+= page
- compound_head(page
);
402 * Return byte-offset into filesystem object for page.
404 static inline loff_t
page_offset(struct page
*page
)
406 return ((loff_t
)page
->index
) << PAGE_SHIFT
;
409 static inline loff_t
page_file_offset(struct page
*page
)
411 return ((loff_t
)page_index(page
)) << PAGE_SHIFT
;
414 extern pgoff_t
linear_hugepage_index(struct vm_area_struct
*vma
,
415 unsigned long address
);
417 static inline pgoff_t
linear_page_index(struct vm_area_struct
*vma
,
418 unsigned long address
)
421 if (unlikely(is_vm_hugetlb_page(vma
)))
422 return linear_hugepage_index(vma
, address
);
423 pgoff
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
424 pgoff
+= vma
->vm_pgoff
;
428 extern void __lock_page(struct page
*page
);
429 extern int __lock_page_killable(struct page
*page
);
430 extern int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
432 extern void unlock_page(struct page
*page
);
434 static inline int trylock_page(struct page
*page
)
436 page
= compound_head(page
);
437 return (likely(!test_and_set_bit_lock(PG_locked
, &page
->flags
)));
441 * lock_page may only be called if we have the page's inode pinned.
443 static inline void lock_page(struct page
*page
)
446 if (!trylock_page(page
))
451 * lock_page_killable is like lock_page but can be interrupted by fatal
452 * signals. It returns 0 if it locked the page and -EINTR if it was
453 * killed while waiting.
455 static inline int lock_page_killable(struct page
*page
)
458 if (!trylock_page(page
))
459 return __lock_page_killable(page
);
464 * lock_page_or_retry - Lock the page, unless this would block and the
465 * caller indicated that it can handle a retry.
467 * Return value and mmap_sem implications depend on flags; see
468 * __lock_page_or_retry().
470 static inline int lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
474 return trylock_page(page
) || __lock_page_or_retry(page
, mm
, flags
);
478 * This is exported only for wait_on_page_locked/wait_on_page_writeback,
479 * and for filesystems which need to wait on PG_private.
481 extern void wait_on_page_bit(struct page
*page
, int bit_nr
);
483 extern int wait_on_page_bit_killable(struct page
*page
, int bit_nr
);
484 extern int wait_on_page_bit_killable_timeout(struct page
*page
,
485 int bit_nr
, unsigned long timeout
);
487 static inline int wait_on_page_locked_killable(struct page
*page
)
489 if (!PageLocked(page
))
491 return wait_on_page_bit_killable(compound_head(page
), PG_locked
);
494 extern wait_queue_head_t
*page_waitqueue(struct page
*page
);
495 static inline void wake_up_page(struct page
*page
, int bit
)
497 __wake_up_bit(page_waitqueue(page
), &page
->flags
, bit
);
501 * Wait for a page to be unlocked.
503 * This must be called with the caller "holding" the page,
504 * ie with increased "page->count" so that the page won't
505 * go away during the wait..
507 static inline void wait_on_page_locked(struct page
*page
)
509 if (PageLocked(page
))
510 wait_on_page_bit(compound_head(page
), PG_locked
);
514 * Wait for a page to complete writeback
516 static inline void wait_on_page_writeback(struct page
*page
)
518 if (PageWriteback(page
))
519 wait_on_page_bit(page
, PG_writeback
);
522 extern void end_page_writeback(struct page
*page
);
523 void wait_for_stable_page(struct page
*page
);
525 void page_endio(struct page
*page
, bool is_write
, int err
);
528 * Add an arbitrary waiter to a page's wait queue
530 extern void add_page_wait_queue(struct page
*page
, wait_queue_t
*waiter
);
533 * Fault everything in given userspace address range in.
535 static inline int fault_in_pages_writeable(char __user
*uaddr
, int size
)
537 char __user
*end
= uaddr
+ size
- 1;
539 if (unlikely(size
== 0))
542 if (unlikely(uaddr
> end
))
545 * Writing zeroes into userspace here is OK, because we know that if
546 * the zero gets there, we'll be overwriting it.
549 if (unlikely(__put_user(0, uaddr
) != 0))
552 } while (uaddr
<= end
);
554 /* Check whether the range spilled into the next page. */
555 if (((unsigned long)uaddr
& PAGE_MASK
) ==
556 ((unsigned long)end
& PAGE_MASK
))
557 return __put_user(0, end
);
562 static inline int fault_in_pages_readable(const char __user
*uaddr
, int size
)
565 const char __user
*end
= uaddr
+ size
- 1;
567 if (unlikely(size
== 0))
570 if (unlikely(uaddr
> end
))
574 if (unlikely(__get_user(c
, uaddr
) != 0))
577 } while (uaddr
<= end
);
579 /* Check whether the range spilled into the next page. */
580 if (((unsigned long)uaddr
& PAGE_MASK
) ==
581 ((unsigned long)end
& PAGE_MASK
)) {
582 return __get_user(c
, end
);
589 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
590 pgoff_t index
, gfp_t gfp_mask
);
591 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
592 pgoff_t index
, gfp_t gfp_mask
);
593 extern void delete_from_page_cache(struct page
*page
);
594 extern void __delete_from_page_cache(struct page
*page
, void *shadow
);
595 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
);
598 * Like add_to_page_cache_locked, but used to add newly allocated pages:
599 * the page is new, so we can just run __SetPageLocked() against it.
601 static inline int add_to_page_cache(struct page
*page
,
602 struct address_space
*mapping
, pgoff_t offset
, gfp_t gfp_mask
)
606 __SetPageLocked(page
);
607 error
= add_to_page_cache_locked(page
, mapping
, offset
, gfp_mask
);
609 __ClearPageLocked(page
);
613 static inline unsigned long dir_pages(struct inode
*inode
)
615 return (unsigned long)(inode
->i_size
+ PAGE_SIZE
- 1) >>
619 #endif /* _LINUX_PAGEMAP_H */