1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PAGEMAP_H
3 #define _LINUX_PAGEMAP_H
6 * Copyright 1995 Linus Torvalds
10 #include <linux/list.h>
11 #include <linux/highmem.h>
12 #include <linux/compiler.h>
13 #include <linux/uaccess.h>
14 #include <linux/gfp.h>
15 #include <linux/bitops.h>
16 #include <linux/hardirq.h> /* for in_interrupt() */
17 #include <linux/hugetlb_inline.h>
21 static inline bool mapping_empty(struct address_space *mapping)
23 return xa_empty(&mapping->i_pages);
27 * Bits in mapping->flags.
30 AS_EIO = 0, /* IO error on async write */
31 AS_ENOSPC = 1, /* ENOSPC on async write */
32 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
33 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
34 AS_EXITING = 4, /* final truncate in progress */
35 /* writeback related tags are not used */
36 AS_NO_WRITEBACK_TAGS = 5,
37 AS_THP_SUPPORT = 6, /* THPs supported */
41 * mapping_set_error - record a writeback error in the address_space
42 * @mapping: the mapping in which an error should be set
43 * @error: the error to set in the mapping
45 * When writeback fails in some way, we must record that error so that
46 * userspace can be informed when fsync and the like are called. We endeavor
47 * to report errors on any file that was open at the time of the error. Some
48 * internal callers also need to know when writeback errors have occurred.
50 * When a writeback error occurs, most filesystems will want to call
51 * mapping_set_error to record the error in the mapping so that it can be
52 * reported when the application calls fsync(2).
54 static inline void mapping_set_error(struct address_space *mapping, int error)
59 /* Record in wb_err for checkers using errseq_t based tracking */
60 __filemap_set_wb_err(mapping, error);
62 /* Record it in superblock */
64 errseq_set(&mapping->host->i_sb->s_wb_err, error);
66 /* Record it in flags for now, for legacy callers */
68 set_bit(AS_ENOSPC, &mapping->flags);
70 set_bit(AS_EIO, &mapping->flags);
73 static inline void mapping_set_unevictable(struct address_space *mapping)
75 set_bit(AS_UNEVICTABLE, &mapping->flags);
78 static inline void mapping_clear_unevictable(struct address_space *mapping)
80 clear_bit(AS_UNEVICTABLE, &mapping->flags);
83 static inline bool mapping_unevictable(struct address_space *mapping)
85 return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags);
88 static inline void mapping_set_exiting(struct address_space *mapping)
90 set_bit(AS_EXITING, &mapping->flags);
93 static inline int mapping_exiting(struct address_space *mapping)
95 return test_bit(AS_EXITING, &mapping->flags);
98 static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
100 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
103 static inline int mapping_use_writeback_tags(struct address_space *mapping)
105 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
108 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
110 return mapping->gfp_mask;
113 /* Restricts the given gfp_mask to what the mapping allows. */
114 static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
117 return mapping_gfp_mask(mapping) & gfp_mask;
121 * This is non-atomic. Only to be used before the mapping is activated.
122 * Probably needs a barrier...
124 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
129 static inline bool mapping_thp_support(struct address_space *mapping)
131 return test_bit(AS_THP_SUPPORT, &mapping->flags);
134 static inline int filemap_nr_thps(struct address_space *mapping)
136 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
137 return atomic_read(&mapping->nr_thps);
143 static inline void filemap_nr_thps_inc(struct address_space *mapping)
145 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
146 if (!mapping_thp_support(mapping))
147 atomic_inc(&mapping->nr_thps);
153 static inline void filemap_nr_thps_dec(struct address_space *mapping)
155 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
156 if (!mapping_thp_support(mapping))
157 atomic_dec(&mapping->nr_thps);
163 void release_pages(struct page **pages, int nr);
166 * For file cache pages, return the address_space, otherwise return NULL
168 static inline struct address_space *page_mapping_file(struct page *page)
170 if (unlikely(PageSwapCache(page)))
172 return page_mapping(page);
176 * speculatively take a reference to a page.
177 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
178 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
180 * This function must be called inside the same rcu_read_lock() section as has
181 * been used to lookup the page in the pagecache radix-tree (or page table):
182 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
184 * Unless an RCU grace period has passed, the count of all pages coming out
185 * of the allocator must be considered unstable. page_count may return higher
186 * than expected, and put_page must be able to do the right thing when the
187 * page has been finished with, no matter what it is subsequently allocated
188 * for (because put_page is what is used here to drop an invalid speculative
191 * This is the interesting part of the lockless pagecache (and lockless
192 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
193 * has the following pattern:
194 * 1. find page in radix tree
195 * 2. conditionally increment refcount
196 * 3. check the page is still in pagecache (if no, goto 1)
198 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
199 * following (with the i_pages lock held):
200 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
201 * B. remove page from pagecache
204 * There are 2 critical interleavings that matter:
205 * - 2 runs before A: in this case, A sees elevated refcount and bails out
206 * - A runs before 2: in this case, 2 sees zero refcount and retries;
207 * subsequently, B will complete and 1 will find no page, causing the
208 * lookup to return NULL.
210 * It is possible that between 1 and 2, the page is removed then the exact same
211 * page is inserted into the same position in pagecache. That's OK: the
212 * old find_get_page using a lock could equally have run before or after
213 * such a re-insertion, depending on order that locks are granted.
215 * Lookups racing against pagecache insertion isn't a big problem: either 1
216 * will find the page or it will not. Likewise, the old find_get_page could run
217 * either before the insertion or afterwards, depending on timing.
219 static inline int __page_cache_add_speculative(struct page *page, int count)
221 #ifdef CONFIG_TINY_RCU
222 # ifdef CONFIG_PREEMPT_COUNT
223 VM_BUG_ON(!in_atomic() && !irqs_disabled());
226 * Preempt must be disabled here - we rely on rcu_read_lock doing
229 * Pagecache won't be truncated from interrupt context, so if we have
230 * found a page in the radix tree here, we have pinned its refcount by
231 * disabling preempt, and hence no need for the "speculative get" that
234 VM_BUG_ON_PAGE(page_count(page) == 0, page);
235 page_ref_add(page, count);
238 if (unlikely(!page_ref_add_unless(page, count, 0))) {
240 * Either the page has been freed, or will be freed.
241 * In either case, retry here and the caller should
242 * do the right thing (see comments above).
247 VM_BUG_ON_PAGE(PageTail(page), page);
252 static inline int page_cache_get_speculative(struct page *page)
254 return __page_cache_add_speculative(page, 1);
257 static inline int page_cache_add_speculative(struct page *page, int count)
259 return __page_cache_add_speculative(page, count);
263 * attach_page_private - Attach private data to a page.
264 * @page: Page to attach data to.
265 * @data: Data to attach to page.
267 * Attaching private data to a page increments the page's reference count.
268 * The data must be detached before the page will be freed.
270 static inline void attach_page_private(struct page *page, void *data)
273 set_page_private(page, (unsigned long)data);
274 SetPagePrivate(page);
278 * detach_page_private - Detach private data from a page.
279 * @page: Page to detach data from.
281 * Removes the data that was previously attached to the page and decrements
282 * the refcount on the page.
284 * Return: Data that was attached to the page.
286 static inline void *detach_page_private(struct page *page)
288 void *data = (void *)page_private(page);
290 if (!PagePrivate(page))
292 ClearPagePrivate(page);
293 set_page_private(page, 0);
300 extern struct page *__page_cache_alloc(gfp_t gfp);
302 static inline struct page *__page_cache_alloc(gfp_t gfp)
304 return alloc_pages(gfp, 0);
308 static inline struct page *page_cache_alloc(struct address_space *x)
310 return __page_cache_alloc(mapping_gfp_mask(x));
313 static inline gfp_t readahead_gfp_mask(struct address_space *x)
315 return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
318 typedef int filler_t(void *, struct page *);
320 pgoff_t page_cache_next_miss(struct address_space *mapping,
321 pgoff_t index, unsigned long max_scan);
322 pgoff_t page_cache_prev_miss(struct address_space *mapping,
323 pgoff_t index, unsigned long max_scan);
325 #define FGP_ACCESSED 0x00000001
326 #define FGP_LOCK 0x00000002
327 #define FGP_CREAT 0x00000004
328 #define FGP_WRITE 0x00000008
329 #define FGP_NOFS 0x00000010
330 #define FGP_NOWAIT 0x00000020
331 #define FGP_FOR_MMAP 0x00000040
332 #define FGP_HEAD 0x00000080
333 #define FGP_ENTRY 0x00000100
335 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
336 int fgp_flags, gfp_t cache_gfp_mask);
339 * find_get_page - find and get a page reference
340 * @mapping: the address_space to search
341 * @offset: the page index
343 * Looks up the page cache slot at @mapping & @offset. If there is a
344 * page cache page, it is returned with an increased refcount.
346 * Otherwise, %NULL is returned.
348 static inline struct page *find_get_page(struct address_space *mapping,
351 return pagecache_get_page(mapping, offset, 0, 0);
354 static inline struct page *find_get_page_flags(struct address_space *mapping,
355 pgoff_t offset, int fgp_flags)
357 return pagecache_get_page(mapping, offset, fgp_flags, 0);
361 * find_lock_page - locate, pin and lock a pagecache page
362 * @mapping: the address_space to search
363 * @index: the page index
365 * Looks up the page cache entry at @mapping & @index. If there is a
366 * page cache page, it is returned locked and with an increased
369 * Context: May sleep.
370 * Return: A struct page or %NULL if there is no page in the cache for this
373 static inline struct page *find_lock_page(struct address_space *mapping,
376 return pagecache_get_page(mapping, index, FGP_LOCK, 0);
380 * find_lock_head - Locate, pin and lock a pagecache page.
381 * @mapping: The address_space to search.
382 * @index: The page index.
384 * Looks up the page cache entry at @mapping & @index. If there is a
385 * page cache page, its head page is returned locked and with an increased
388 * Context: May sleep.
389 * Return: A struct page which is !PageTail, or %NULL if there is no page
390 * in the cache for this index.
392 static inline struct page *find_lock_head(struct address_space *mapping,
395 return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
399 * find_or_create_page - locate or add a pagecache page
400 * @mapping: the page's address_space
401 * @index: the page's index into the mapping
402 * @gfp_mask: page allocation mode
404 * Looks up the page cache slot at @mapping & @offset. If there is a
405 * page cache page, it is returned locked and with an increased
408 * If the page is not present, a new page is allocated using @gfp_mask
409 * and added to the page cache and the VM's LRU list. The page is
410 * returned locked and with an increased refcount.
412 * On memory exhaustion, %NULL is returned.
414 * find_or_create_page() may sleep, even if @gfp_flags specifies an
417 static inline struct page *find_or_create_page(struct address_space *mapping,
418 pgoff_t index, gfp_t gfp_mask)
420 return pagecache_get_page(mapping, index,
421 FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
426 * grab_cache_page_nowait - returns locked page at given index in given cache
427 * @mapping: target address_space
428 * @index: the page index
430 * Same as grab_cache_page(), but do not wait if the page is unavailable.
431 * This is intended for speculative data generators, where the data can
432 * be regenerated if the page couldn't be grabbed. This routine should
433 * be safe to call while holding the lock for another page.
435 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
436 * and deadlock against the caller's locked page.
438 static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
441 return pagecache_get_page(mapping, index,
442 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
443 mapping_gfp_mask(mapping));
446 /* Does this page contain this index? */
447 static inline bool thp_contains(struct page *head, pgoff_t index)
449 /* HugeTLBfs indexes the page cache in units of hpage_size */
451 return head->index == index;
452 return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
456 * Given the page we found in the page cache, return the page corresponding
457 * to this index in the file
459 static inline struct page *find_subpage(struct page *head, pgoff_t index)
461 /* HugeTLBfs wants the head page regardless */
465 return head + (index & (thp_nr_pages(head) - 1));
468 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
469 pgoff_t end, struct pagevec *pvec, pgoff_t *indices);
470 unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
471 pgoff_t end, unsigned int nr_pages,
472 struct page **pages);
473 static inline unsigned find_get_pages(struct address_space *mapping,
474 pgoff_t *start, unsigned int nr_pages,
477 return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
480 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
481 unsigned int nr_pages, struct page **pages);
482 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
483 pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
484 struct page **pages);
485 static inline unsigned find_get_pages_tag(struct address_space *mapping,
486 pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
489 return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
493 struct page *grab_cache_page_write_begin(struct address_space *mapping,
494 pgoff_t index, unsigned flags);
497 * Returns locked page at given index in given cache, creating it if needed.
499 static inline struct page *grab_cache_page(struct address_space *mapping,
502 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
505 extern struct page * read_cache_page(struct address_space *mapping,
506 pgoff_t index, filler_t *filler, void *data);
507 extern struct page * read_cache_page_gfp(struct address_space *mapping,
508 pgoff_t index, gfp_t gfp_mask);
509 extern int read_cache_pages(struct address_space *mapping,
510 struct list_head *pages, filler_t *filler, void *data);
512 static inline struct page *read_mapping_page(struct address_space *mapping,
513 pgoff_t index, void *data)
515 return read_cache_page(mapping, index, NULL, data);
519 * Get index of the page with in radix-tree
520 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
522 static inline pgoff_t page_to_index(struct page *page)
526 if (likely(!PageTransTail(page)))
530 * We don't initialize ->index for tail pages: calculate based on
533 pgoff = compound_head(page)->index;
534 pgoff += page - compound_head(page);
539 * Get the offset in PAGE_SIZE.
540 * (TODO: hugepage should have ->index in PAGE_SIZE)
542 static inline pgoff_t page_to_pgoff(struct page *page)
544 if (unlikely(PageHeadHuge(page)))
545 return page->index << compound_order(page);
547 return page_to_index(page);
551 * Return byte-offset into filesystem object for page.
553 static inline loff_t page_offset(struct page *page)
555 return ((loff_t)page->index) << PAGE_SHIFT;
558 static inline loff_t page_file_offset(struct page *page)
560 return ((loff_t)page_index(page)) << PAGE_SHIFT;
563 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
564 unsigned long address);
566 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
567 unsigned long address)
570 if (unlikely(is_vm_hugetlb_page(vma)))
571 return linear_hugepage_index(vma, address);
572 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
573 pgoff += vma->vm_pgoff;
577 struct wait_page_key {
583 struct wait_page_queue {
586 wait_queue_entry_t wait;
589 static inline bool wake_page_match(struct wait_page_queue *wait_page,
590 struct wait_page_key *key)
592 if (wait_page->page != key->page)
596 if (wait_page->bit_nr != key->bit_nr)
602 extern void __lock_page(struct page *page);
603 extern int __lock_page_killable(struct page *page);
604 extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
605 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
607 extern void unlock_page(struct page *page);
610 * Return true if the page was successfully locked
612 static inline int trylock_page(struct page *page)
614 page = compound_head(page);
615 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
619 * lock_page may only be called if we have the page's inode pinned.
621 static inline void lock_page(struct page *page)
624 if (!trylock_page(page))
629 * lock_page_killable is like lock_page but can be interrupted by fatal
630 * signals. It returns 0 if it locked the page and -EINTR if it was
631 * killed while waiting.
633 static inline int lock_page_killable(struct page *page)
636 if (!trylock_page(page))
637 return __lock_page_killable(page);
642 * lock_page_async - Lock the page, unless this would block. If the page
643 * is already locked, then queue a callback when the page becomes unlocked.
644 * This callback can then retry the operation.
646 * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page
647 * was already locked and the callback defined in 'wait' was queued.
649 static inline int lock_page_async(struct page *page,
650 struct wait_page_queue *wait)
652 if (!trylock_page(page))
653 return __lock_page_async(page, wait);
658 * lock_page_or_retry - Lock the page, unless this would block and the
659 * caller indicated that it can handle a retry.
661 * Return value and mmap_lock implications depend on flags; see
662 * __lock_page_or_retry().
664 static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
668 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
672 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
673 * and should not be used directly.
675 extern void wait_on_page_bit(struct page *page, int bit_nr);
676 extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
679 * Wait for a page to be unlocked.
681 * This must be called with the caller "holding" the page,
682 * ie with increased "page->count" so that the page won't
683 * go away during the wait..
685 static inline void wait_on_page_locked(struct page *page)
687 if (PageLocked(page))
688 wait_on_page_bit(compound_head(page), PG_locked);
691 static inline int wait_on_page_locked_killable(struct page *page)
693 if (!PageLocked(page))
695 return wait_on_page_bit_killable(compound_head(page), PG_locked);
698 int put_and_wait_on_page_locked(struct page *page, int state);
699 void wait_on_page_writeback(struct page *page);
700 int wait_on_page_writeback_killable(struct page *page);
701 extern void end_page_writeback(struct page *page);
702 void wait_for_stable_page(struct page *page);
704 void page_endio(struct page *page, bool is_write, int err);
707 * set_page_private_2 - Set PG_private_2 on a page and take a ref
710 * Set the PG_private_2 flag on a page and take the reference needed for the VM
711 * to handle its lifetime correctly. This sets the flag and takes the
712 * reference unconditionally, so care must be taken not to set the flag again
713 * if it's already set.
715 static inline void set_page_private_2(struct page *page)
717 page = compound_head(page);
719 SetPagePrivate2(page);
722 void end_page_private_2(struct page *page);
723 void wait_on_page_private_2(struct page *page);
724 int wait_on_page_private_2_killable(struct page *page);
727 * Add an arbitrary waiter to a page's wait queue
729 extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
732 * Fault everything in given userspace address range in.
734 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
736 char __user *end = uaddr + size - 1;
738 if (unlikely(size == 0))
741 if (unlikely(uaddr > end))
744 * Writing zeroes into userspace here is OK, because we know that if
745 * the zero gets there, we'll be overwriting it.
748 if (unlikely(__put_user(0, uaddr) != 0))
751 } while (uaddr <= end);
753 /* Check whether the range spilled into the next page. */
754 if (((unsigned long)uaddr & PAGE_MASK) ==
755 ((unsigned long)end & PAGE_MASK))
756 return __put_user(0, end);
761 static inline int fault_in_pages_readable(const char __user *uaddr, int size)
764 const char __user *end = uaddr + size - 1;
766 if (unlikely(size == 0))
769 if (unlikely(uaddr > end))
773 if (unlikely(__get_user(c, uaddr) != 0))
776 } while (uaddr <= end);
778 /* Check whether the range spilled into the next page. */
779 if (((unsigned long)uaddr & PAGE_MASK) ==
780 ((unsigned long)end & PAGE_MASK)) {
781 return __get_user(c, end);
788 int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
789 pgoff_t index, gfp_t gfp_mask);
790 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
791 pgoff_t index, gfp_t gfp_mask);
792 extern void delete_from_page_cache(struct page *page);
793 extern void __delete_from_page_cache(struct page *page, void *shadow);
794 void replace_page_cache_page(struct page *old, struct page *new);
795 void delete_from_page_cache_batch(struct address_space *mapping,
796 struct pagevec *pvec);
797 loff_t mapping_seek_hole_data(struct address_space *, loff_t start, loff_t end,
801 * Like add_to_page_cache_locked, but used to add newly allocated pages:
802 * the page is new, so we can just run __SetPageLocked() against it.
804 static inline int add_to_page_cache(struct page *page,
805 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
809 __SetPageLocked(page);
810 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
812 __ClearPageLocked(page);
817 * struct readahead_control - Describes a readahead request.
819 * A readahead request is for consecutive pages. Filesystems which
820 * implement the ->readahead method should call readahead_page() or
821 * readahead_page_batch() in a loop and attempt to start I/O against
822 * each page in the request.
824 * Most of the fields in this struct are private and should be accessed
825 * by the functions below.
827 * @file: The file, used primarily by network filesystems for authentication.
828 * May be NULL if invoked internally by the filesystem.
829 * @mapping: Readahead this filesystem object.
830 * @ra: File readahead state. May be NULL.
832 struct readahead_control {
834 struct address_space *mapping;
835 struct file_ra_state *ra;
836 /* private: use the readahead_* accessors instead */
838 unsigned int _nr_pages;
839 unsigned int _batch_count;
842 #define DEFINE_READAHEAD(ractl, f, r, m, i) \
843 struct readahead_control ractl = { \
850 #define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
852 void page_cache_ra_unbounded(struct readahead_control *,
853 unsigned long nr_to_read, unsigned long lookahead_count);
854 void page_cache_sync_ra(struct readahead_control *, unsigned long req_count);
855 void page_cache_async_ra(struct readahead_control *, struct page *,
856 unsigned long req_count);
857 void readahead_expand(struct readahead_control *ractl,
858 loff_t new_start, size_t new_len);
861 * page_cache_sync_readahead - generic file readahead
862 * @mapping: address_space which holds the pagecache and I/O vectors
863 * @ra: file_ra_state which holds the readahead state
864 * @file: Used by the filesystem for authentication.
865 * @index: Index of first page to be read.
866 * @req_count: Total number of pages being read by the caller.
868 * page_cache_sync_readahead() should be called when a cache miss happened:
869 * it will submit the read. The readahead logic may decide to piggyback more
870 * pages onto the read request if access patterns suggest it will improve
874 void page_cache_sync_readahead(struct address_space *mapping,
875 struct file_ra_state *ra, struct file *file, pgoff_t index,
876 unsigned long req_count)
878 DEFINE_READAHEAD(ractl, file, ra, mapping, index);
879 page_cache_sync_ra(&ractl, req_count);
883 * page_cache_async_readahead - file readahead for marked pages
884 * @mapping: address_space which holds the pagecache and I/O vectors
885 * @ra: file_ra_state which holds the readahead state
886 * @file: Used by the filesystem for authentication.
887 * @page: The page at @index which triggered the readahead call.
888 * @index: Index of first page to be read.
889 * @req_count: Total number of pages being read by the caller.
891 * page_cache_async_readahead() should be called when a page is used which
892 * is marked as PageReadahead; this is a marker to suggest that the application
893 * has used up enough of the readahead window that we should start pulling in
897 void page_cache_async_readahead(struct address_space *mapping,
898 struct file_ra_state *ra, struct file *file,
899 struct page *page, pgoff_t index, unsigned long req_count)
901 DEFINE_READAHEAD(ractl, file, ra, mapping, index);
902 page_cache_async_ra(&ractl, page, req_count);
906 * readahead_page - Get the next page to read.
907 * @rac: The current readahead request.
909 * Context: The page is locked and has an elevated refcount. The caller
910 * should decreases the refcount once the page has been submitted for I/O
911 * and unlock the page once all I/O to that page has completed.
912 * Return: A pointer to the next page, or %NULL if we are done.
914 static inline struct page *readahead_page(struct readahead_control *rac)
918 BUG_ON(rac->_batch_count > rac->_nr_pages);
919 rac->_nr_pages -= rac->_batch_count;
920 rac->_index += rac->_batch_count;
922 if (!rac->_nr_pages) {
923 rac->_batch_count = 0;
927 page = xa_load(&rac->mapping->i_pages, rac->_index);
928 VM_BUG_ON_PAGE(!PageLocked(page), page);
929 rac->_batch_count = thp_nr_pages(page);
934 static inline unsigned int __readahead_batch(struct readahead_control *rac,
935 struct page **array, unsigned int array_sz)
938 XA_STATE(xas, &rac->mapping->i_pages, 0);
941 BUG_ON(rac->_batch_count > rac->_nr_pages);
942 rac->_nr_pages -= rac->_batch_count;
943 rac->_index += rac->_batch_count;
944 rac->_batch_count = 0;
946 xas_set(&xas, rac->_index);
948 xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
949 if (xas_retry(&xas, page))
951 VM_BUG_ON_PAGE(!PageLocked(page), page);
952 VM_BUG_ON_PAGE(PageTail(page), page);
954 rac->_batch_count += thp_nr_pages(page);
957 * The page cache isn't using multi-index entries yet,
958 * so the xas cursor needs to be manually moved to the
959 * next index. This can be removed once the page cache
963 xas_set(&xas, rac->_index + rac->_batch_count);
974 * readahead_page_batch - Get a batch of pages to read.
975 * @rac: The current readahead request.
976 * @array: An array of pointers to struct page.
978 * Context: The pages are locked and have an elevated refcount. The caller
979 * should decreases the refcount once the page has been submitted for I/O
980 * and unlock the page once all I/O to that page has completed.
981 * Return: The number of pages placed in the array. 0 indicates the request
984 #define readahead_page_batch(rac, array) \
985 __readahead_batch(rac, array, ARRAY_SIZE(array))
988 * readahead_pos - The byte offset into the file of this readahead request.
989 * @rac: The readahead request.
991 static inline loff_t readahead_pos(struct readahead_control *rac)
993 return (loff_t)rac->_index * PAGE_SIZE;
997 * readahead_length - The number of bytes in this readahead request.
998 * @rac: The readahead request.
1000 static inline size_t readahead_length(struct readahead_control *rac)
1002 return rac->_nr_pages * PAGE_SIZE;
1006 * readahead_index - The index of the first page in this readahead request.
1007 * @rac: The readahead request.
1009 static inline pgoff_t readahead_index(struct readahead_control *rac)
1015 * readahead_count - The number of pages in this readahead request.
1016 * @rac: The readahead request.
1018 static inline unsigned int readahead_count(struct readahead_control *rac)
1020 return rac->_nr_pages;
1024 * readahead_batch_length - The number of bytes in the current batch.
1025 * @rac: The readahead request.
1027 static inline size_t readahead_batch_length(struct readahead_control *rac)
1029 return rac->_batch_count * PAGE_SIZE;
1032 static inline unsigned long dir_pages(struct inode *inode)
1034 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
1039 * page_mkwrite_check_truncate - check if page was truncated
1040 * @page: the page to check
1041 * @inode: the inode to check the page against
1043 * Returns the number of bytes in the page up to EOF,
1044 * or -EFAULT if the page was truncated.
1046 static inline int page_mkwrite_check_truncate(struct page *page,
1047 struct inode *inode)
1049 loff_t size = i_size_read(inode);
1050 pgoff_t index = size >> PAGE_SHIFT;
1051 int offset = offset_in_page(size);
1053 if (page->mapping != inode->i_mapping)
1056 /* page is wholly inside EOF */
1057 if (page->index < index)
1059 /* page is wholly past EOF */
1060 if (page->index > index || !offset)
1062 /* page is partially inside EOF */
1067 * i_blocks_per_page - How many blocks fit in this page.
1068 * @inode: The inode which contains the blocks.
1069 * @page: The page (head page if the page is a THP).
1071 * If the block size is larger than the size of this page, return zero.
1073 * Context: The caller should hold a refcount on the page to prevent it
1075 * Return: The number of filesystem blocks covered by this page.
1078 unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
1080 return thp_size(page) >> inode->i_blkbits;
1082 #endif /* _LINUX_PAGEMAP_H */