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git.proxmox.com Git - mirror_ubuntu-bionic-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 <linux/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.
22 AS_EIO
= 0, /* IO error on async write */
23 AS_ENOSPC
= 1, /* ENOSPC on async write */
24 AS_MM_ALL_LOCKS
= 2, /* under mm_take_all_locks() */
25 AS_UNEVICTABLE
= 3, /* e.g., ramdisk, SHM_LOCK */
26 AS_EXITING
= 4, /* final truncate in progress */
27 /* writeback related tags are not used */
28 AS_NO_WRITEBACK_TAGS
= 5,
32 * mapping_set_error - record a writeback error in the address_space
33 * @mapping - the mapping in which an error should be set
34 * @error - the error to set in the mapping
36 * When writeback fails in some way, we must record that error so that
37 * userspace can be informed when fsync and the like are called. We endeavor
38 * to report errors on any file that was open at the time of the error. Some
39 * internal callers also need to know when writeback errors have occurred.
41 * When a writeback error occurs, most filesystems will want to call
42 * mapping_set_error to record the error in the mapping so that it can be
43 * reported when the application calls fsync(2).
45 static inline void mapping_set_error(struct address_space
*mapping
, int error
)
50 /* Record in wb_err for checkers using errseq_t based tracking */
51 filemap_set_wb_err(mapping
, error
);
53 /* Record it in flags for now, for legacy callers */
55 set_bit(AS_ENOSPC
, &mapping
->flags
);
57 set_bit(AS_EIO
, &mapping
->flags
);
60 static inline void mapping_set_unevictable(struct address_space
*mapping
)
62 set_bit(AS_UNEVICTABLE
, &mapping
->flags
);
65 static inline void mapping_clear_unevictable(struct address_space
*mapping
)
67 clear_bit(AS_UNEVICTABLE
, &mapping
->flags
);
70 static inline int mapping_unevictable(struct address_space
*mapping
)
73 return test_bit(AS_UNEVICTABLE
, &mapping
->flags
);
77 static inline void mapping_set_exiting(struct address_space
*mapping
)
79 set_bit(AS_EXITING
, &mapping
->flags
);
82 static inline int mapping_exiting(struct address_space
*mapping
)
84 return test_bit(AS_EXITING
, &mapping
->flags
);
87 static inline void mapping_set_no_writeback_tags(struct address_space
*mapping
)
89 set_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
92 static inline int mapping_use_writeback_tags(struct address_space
*mapping
)
94 return !test_bit(AS_NO_WRITEBACK_TAGS
, &mapping
->flags
);
97 static inline gfp_t
mapping_gfp_mask(struct address_space
* mapping
)
99 return mapping
->gfp_mask
;
102 /* Restricts the given gfp_mask to what the mapping allows. */
103 static inline gfp_t
mapping_gfp_constraint(struct address_space
*mapping
,
106 return mapping_gfp_mask(mapping
) & gfp_mask
;
110 * This is non-atomic. Only to be used before the mapping is activated.
111 * Probably needs a barrier...
113 static inline void mapping_set_gfp_mask(struct address_space
*m
, gfp_t mask
)
118 void release_pages(struct page
**pages
, int nr
, bool cold
);
121 * speculatively take a reference to a page.
122 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
123 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
125 * This function must be called inside the same rcu_read_lock() section as has
126 * been used to lookup the page in the pagecache radix-tree (or page table):
127 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
129 * Unless an RCU grace period has passed, the count of all pages coming out
130 * of the allocator must be considered unstable. page_count may return higher
131 * than expected, and put_page must be able to do the right thing when the
132 * page has been finished with, no matter what it is subsequently allocated
133 * for (because put_page is what is used here to drop an invalid speculative
136 * This is the interesting part of the lockless pagecache (and lockless
137 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
138 * has the following pattern:
139 * 1. find page in radix tree
140 * 2. conditionally increment refcount
141 * 3. check the page is still in pagecache (if no, goto 1)
143 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
144 * following (with tree_lock held for write):
145 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
146 * B. remove page from pagecache
149 * There are 2 critical interleavings that matter:
150 * - 2 runs before A: in this case, A sees elevated refcount and bails out
151 * - A runs before 2: in this case, 2 sees zero refcount and retries;
152 * subsequently, B will complete and 1 will find no page, causing the
153 * lookup to return NULL.
155 * It is possible that between 1 and 2, the page is removed then the exact same
156 * page is inserted into the same position in pagecache. That's OK: the
157 * old find_get_page using tree_lock could equally have run before or after
158 * such a re-insertion, depending on order that locks are granted.
160 * Lookups racing against pagecache insertion isn't a big problem: either 1
161 * will find the page or it will not. Likewise, the old find_get_page could run
162 * either before the insertion or afterwards, depending on timing.
164 static inline int page_cache_get_speculative(struct page
*page
)
166 #ifdef CONFIG_TINY_RCU
167 # ifdef CONFIG_PREEMPT_COUNT
168 VM_BUG_ON(!in_atomic() && !irqs_disabled());
171 * Preempt must be disabled here - we rely on rcu_read_lock doing
174 * Pagecache won't be truncated from interrupt context, so if we have
175 * found a page in the radix tree here, we have pinned its refcount by
176 * disabling preempt, and hence no need for the "speculative get" that
179 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
183 if (unlikely(!get_page_unless_zero(page
))) {
185 * Either the page has been freed, or will be freed.
186 * In either case, retry here and the caller should
187 * do the right thing (see comments above).
192 VM_BUG_ON_PAGE(PageTail(page
), page
);
198 * Same as above, but add instead of inc (could just be merged)
200 static inline int page_cache_add_speculative(struct page
*page
, int count
)
202 VM_BUG_ON(in_interrupt());
204 #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
205 # ifdef CONFIG_PREEMPT_COUNT
206 VM_BUG_ON(!in_atomic() && !irqs_disabled());
208 VM_BUG_ON_PAGE(page_count(page
) == 0, page
);
209 page_ref_add(page
, count
);
212 if (unlikely(!page_ref_add_unless(page
, count
, 0)))
215 VM_BUG_ON_PAGE(PageCompound(page
) && page
!= compound_head(page
), page
);
221 extern struct page
*__page_cache_alloc(gfp_t gfp
);
223 static inline struct page
*__page_cache_alloc(gfp_t gfp
)
225 return alloc_pages(gfp
, 0);
229 static inline struct page
*page_cache_alloc(struct address_space
*x
)
231 return __page_cache_alloc(mapping_gfp_mask(x
));
234 static inline struct page
*page_cache_alloc_cold(struct address_space
*x
)
236 return __page_cache_alloc(mapping_gfp_mask(x
)|__GFP_COLD
);
239 static inline gfp_t
readahead_gfp_mask(struct address_space
*x
)
241 return mapping_gfp_mask(x
) |
242 __GFP_COLD
| __GFP_NORETRY
| __GFP_NOWARN
;
245 typedef int filler_t(void *, struct page
*);
247 pgoff_t
page_cache_next_hole(struct address_space
*mapping
,
248 pgoff_t index
, unsigned long max_scan
);
249 pgoff_t
page_cache_prev_hole(struct address_space
*mapping
,
250 pgoff_t index
, unsigned long max_scan
);
252 #define FGP_ACCESSED 0x00000001
253 #define FGP_LOCK 0x00000002
254 #define FGP_CREAT 0x00000004
255 #define FGP_WRITE 0x00000008
256 #define FGP_NOFS 0x00000010
257 #define FGP_NOWAIT 0x00000020
259 struct page
*pagecache_get_page(struct address_space
*mapping
, pgoff_t offset
,
260 int fgp_flags
, gfp_t cache_gfp_mask
);
263 * find_get_page - find and get a page reference
264 * @mapping: the address_space to search
265 * @offset: the page index
267 * Looks up the page cache slot at @mapping & @offset. If there is a
268 * page cache page, it is returned with an increased refcount.
270 * Otherwise, %NULL is returned.
272 static inline struct page
*find_get_page(struct address_space
*mapping
,
275 return pagecache_get_page(mapping
, offset
, 0, 0);
278 static inline struct page
*find_get_page_flags(struct address_space
*mapping
,
279 pgoff_t offset
, int fgp_flags
)
281 return pagecache_get_page(mapping
, offset
, fgp_flags
, 0);
285 * find_lock_page - locate, pin and lock a pagecache page
286 * @mapping: the address_space to search
287 * @offset: the page index
289 * Looks up the page cache slot at @mapping & @offset. If there is a
290 * page cache page, it is returned locked and with an increased
293 * Otherwise, %NULL is returned.
295 * find_lock_page() may sleep.
297 static inline struct page
*find_lock_page(struct address_space
*mapping
,
300 return pagecache_get_page(mapping
, offset
, FGP_LOCK
, 0);
304 * find_or_create_page - locate or add a pagecache page
305 * @mapping: the page's address_space
306 * @index: the page's index into the mapping
307 * @gfp_mask: page allocation mode
309 * Looks up the page cache slot at @mapping & @offset. If there is a
310 * page cache page, it is returned locked and with an increased
313 * If the page is not present, a new page is allocated using @gfp_mask
314 * and added to the page cache and the VM's LRU list. The page is
315 * returned locked and with an increased refcount.
317 * On memory exhaustion, %NULL is returned.
319 * find_or_create_page() may sleep, even if @gfp_flags specifies an
322 static inline struct page
*find_or_create_page(struct address_space
*mapping
,
323 pgoff_t offset
, gfp_t gfp_mask
)
325 return pagecache_get_page(mapping
, offset
,
326 FGP_LOCK
|FGP_ACCESSED
|FGP_CREAT
,
331 * grab_cache_page_nowait - returns locked page at given index in given cache
332 * @mapping: target address_space
333 * @index: the page index
335 * Same as grab_cache_page(), but do not wait if the page is unavailable.
336 * This is intended for speculative data generators, where the data can
337 * be regenerated if the page couldn't be grabbed. This routine should
338 * be safe to call while holding the lock for another page.
340 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
341 * and deadlock against the caller's locked page.
343 static inline struct page
*grab_cache_page_nowait(struct address_space
*mapping
,
346 return pagecache_get_page(mapping
, index
,
347 FGP_LOCK
|FGP_CREAT
|FGP_NOFS
|FGP_NOWAIT
,
348 mapping_gfp_mask(mapping
));
351 struct page
*find_get_entry(struct address_space
*mapping
, pgoff_t offset
);
352 struct page
*find_lock_entry(struct address_space
*mapping
, pgoff_t offset
);
353 unsigned find_get_entries(struct address_space
*mapping
, pgoff_t start
,
354 unsigned int nr_entries
, struct page
**entries
,
356 unsigned find_get_pages_range(struct address_space
*mapping
, pgoff_t
*start
,
357 pgoff_t end
, unsigned int nr_pages
,
358 struct page
**pages
);
359 static inline unsigned find_get_pages(struct address_space
*mapping
,
360 pgoff_t
*start
, unsigned int nr_pages
,
363 return find_get_pages_range(mapping
, start
, (pgoff_t
)-1, nr_pages
,
366 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t start
,
367 unsigned int nr_pages
, struct page
**pages
);
368 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
369 int tag
, unsigned int nr_pages
, struct page
**pages
);
370 unsigned find_get_entries_tag(struct address_space
*mapping
, pgoff_t start
,
371 int tag
, unsigned int nr_entries
,
372 struct page
**entries
, pgoff_t
*indices
);
374 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
375 pgoff_t index
, unsigned flags
);
378 * Returns locked page at given index in given cache, creating it if needed.
380 static inline struct page
*grab_cache_page(struct address_space
*mapping
,
383 return find_or_create_page(mapping
, index
, mapping_gfp_mask(mapping
));
386 extern struct page
* read_cache_page(struct address_space
*mapping
,
387 pgoff_t index
, filler_t
*filler
, void *data
);
388 extern struct page
* read_cache_page_gfp(struct address_space
*mapping
,
389 pgoff_t index
, gfp_t gfp_mask
);
390 extern int read_cache_pages(struct address_space
*mapping
,
391 struct list_head
*pages
, filler_t
*filler
, void *data
);
393 static inline struct page
*read_mapping_page(struct address_space
*mapping
,
394 pgoff_t index
, void *data
)
396 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
397 return read_cache_page(mapping
, index
, filler
, data
);
401 * Get index of the page with in radix-tree
402 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
404 static inline pgoff_t
page_to_index(struct page
*page
)
408 if (likely(!PageTransTail(page
)))
412 * We don't initialize ->index for tail pages: calculate based on
415 pgoff
= compound_head(page
)->index
;
416 pgoff
+= page
- compound_head(page
);
421 * Get the offset in PAGE_SIZE.
422 * (TODO: hugepage should have ->index in PAGE_SIZE)
424 static inline pgoff_t
page_to_pgoff(struct page
*page
)
426 if (unlikely(PageHeadHuge(page
)))
427 return page
->index
<< compound_order(page
);
429 return page_to_index(page
);
433 * Return byte-offset into filesystem object for page.
435 static inline loff_t
page_offset(struct page
*page
)
437 return ((loff_t
)page
->index
) << PAGE_SHIFT
;
440 static inline loff_t
page_file_offset(struct page
*page
)
442 return ((loff_t
)page_index(page
)) << PAGE_SHIFT
;
445 extern pgoff_t
linear_hugepage_index(struct vm_area_struct
*vma
,
446 unsigned long address
);
448 static inline pgoff_t
linear_page_index(struct vm_area_struct
*vma
,
449 unsigned long address
)
452 if (unlikely(is_vm_hugetlb_page(vma
)))
453 return linear_hugepage_index(vma
, address
);
454 pgoff
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
455 pgoff
+= vma
->vm_pgoff
;
459 extern void __lock_page(struct page
*page
);
460 extern int __lock_page_killable(struct page
*page
);
461 extern int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
463 extern void unlock_page(struct page
*page
);
465 static inline int trylock_page(struct page
*page
)
467 page
= compound_head(page
);
468 return (likely(!test_and_set_bit_lock(PG_locked
, &page
->flags
)));
472 * lock_page may only be called if we have the page's inode pinned.
474 static inline void lock_page(struct page
*page
)
477 if (!trylock_page(page
))
482 * lock_page_killable is like lock_page but can be interrupted by fatal
483 * signals. It returns 0 if it locked the page and -EINTR if it was
484 * killed while waiting.
486 static inline int lock_page_killable(struct page
*page
)
489 if (!trylock_page(page
))
490 return __lock_page_killable(page
);
495 * lock_page_or_retry - Lock the page, unless this would block and the
496 * caller indicated that it can handle a retry.
498 * Return value and mmap_sem implications depend on flags; see
499 * __lock_page_or_retry().
501 static inline int lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
505 return trylock_page(page
) || __lock_page_or_retry(page
, mm
, flags
);
509 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
510 * and should not be used directly.
512 extern void wait_on_page_bit(struct page
*page
, int bit_nr
);
513 extern int wait_on_page_bit_killable(struct page
*page
, int bit_nr
);
516 * Wait for a page to be unlocked.
518 * This must be called with the caller "holding" the page,
519 * ie with increased "page->count" so that the page won't
520 * go away during the wait..
522 static inline void wait_on_page_locked(struct page
*page
)
524 if (PageLocked(page
))
525 wait_on_page_bit(compound_head(page
), PG_locked
);
528 static inline int wait_on_page_locked_killable(struct page
*page
)
530 if (!PageLocked(page
))
532 return wait_on_page_bit_killable(compound_head(page
), PG_locked
);
536 * Wait for a page to complete writeback
538 static inline void wait_on_page_writeback(struct page
*page
)
540 if (PageWriteback(page
))
541 wait_on_page_bit(page
, PG_writeback
);
544 extern void end_page_writeback(struct page
*page
);
545 void wait_for_stable_page(struct page
*page
);
547 void page_endio(struct page
*page
, bool is_write
, int err
);
550 * Add an arbitrary waiter to a page's wait queue
552 extern void add_page_wait_queue(struct page
*page
, wait_queue_entry_t
*waiter
);
555 * Fault everything in given userspace address range in.
557 static inline int fault_in_pages_writeable(char __user
*uaddr
, int size
)
559 char __user
*end
= uaddr
+ size
- 1;
561 if (unlikely(size
== 0))
564 if (unlikely(uaddr
> end
))
567 * Writing zeroes into userspace here is OK, because we know that if
568 * the zero gets there, we'll be overwriting it.
571 if (unlikely(__put_user(0, uaddr
) != 0))
574 } while (uaddr
<= end
);
576 /* Check whether the range spilled into the next page. */
577 if (((unsigned long)uaddr
& PAGE_MASK
) ==
578 ((unsigned long)end
& PAGE_MASK
))
579 return __put_user(0, end
);
584 static inline int fault_in_pages_readable(const char __user
*uaddr
, int size
)
587 const char __user
*end
= uaddr
+ size
- 1;
589 if (unlikely(size
== 0))
592 if (unlikely(uaddr
> end
))
596 if (unlikely(__get_user(c
, uaddr
) != 0))
599 } while (uaddr
<= end
);
601 /* Check whether the range spilled into the next page. */
602 if (((unsigned long)uaddr
& PAGE_MASK
) ==
603 ((unsigned long)end
& PAGE_MASK
)) {
604 return __get_user(c
, end
);
611 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
612 pgoff_t index
, gfp_t gfp_mask
);
613 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
614 pgoff_t index
, gfp_t gfp_mask
);
615 extern void delete_from_page_cache(struct page
*page
);
616 extern void __delete_from_page_cache(struct page
*page
, void *shadow
);
617 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
);
620 * Like add_to_page_cache_locked, but used to add newly allocated pages:
621 * the page is new, so we can just run __SetPageLocked() against it.
623 static inline int add_to_page_cache(struct page
*page
,
624 struct address_space
*mapping
, pgoff_t offset
, gfp_t gfp_mask
)
628 __SetPageLocked(page
);
629 error
= add_to_page_cache_locked(page
, mapping
, offset
, gfp_mask
);
631 __ClearPageLocked(page
);
635 static inline unsigned long dir_pages(struct inode
*inode
)
637 return (unsigned long)(inode
->i_size
+ PAGE_SIZE
- 1) >>
641 #endif /* _LINUX_PAGEMAP_H */