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>
22 * Bits in mapping->flags.
25 AS_EIO = 0, /* IO error on async write */
26 AS_ENOSPC = 1, /* ENOSPC on async write */
27 AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
28 AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
29 AS_EXITING = 4, /* final truncate in progress */
30 /* writeback related tags are not used */
31 AS_NO_WRITEBACK_TAGS = 5,
32 AS_THP_SUPPORT = 6, /* THPs supported */
36 * mapping_set_error - record a writeback error in the address_space
37 * @mapping: the mapping in which an error should be set
38 * @error: the error to set in the mapping
40 * When writeback fails in some way, we must record that error so that
41 * userspace can be informed when fsync and the like are called. We endeavor
42 * to report errors on any file that was open at the time of the error. Some
43 * internal callers also need to know when writeback errors have occurred.
45 * When a writeback error occurs, most filesystems will want to call
46 * mapping_set_error to record the error in the mapping so that it can be
47 * reported when the application calls fsync(2).
49 static inline void mapping_set_error(struct address_space *mapping, int error)
54 /* Record in wb_err for checkers using errseq_t based tracking */
55 __filemap_set_wb_err(mapping, error);
57 /* Record it in superblock */
59 errseq_set(&mapping->host->i_sb->s_wb_err, error);
61 /* Record it in flags for now, for legacy callers */
63 set_bit(AS_ENOSPC, &mapping->flags);
65 set_bit(AS_EIO, &mapping->flags);
68 static inline void mapping_set_unevictable(struct address_space *mapping)
70 set_bit(AS_UNEVICTABLE, &mapping->flags);
73 static inline void mapping_clear_unevictable(struct address_space *mapping)
75 clear_bit(AS_UNEVICTABLE, &mapping->flags);
78 static inline bool mapping_unevictable(struct address_space *mapping)
80 return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags);
83 static inline void mapping_set_exiting(struct address_space *mapping)
85 set_bit(AS_EXITING, &mapping->flags);
88 static inline int mapping_exiting(struct address_space *mapping)
90 return test_bit(AS_EXITING, &mapping->flags);
93 static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
95 set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
98 static inline int mapping_use_writeback_tags(struct address_space *mapping)
100 return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
103 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
105 return mapping->gfp_mask;
108 /* Restricts the given gfp_mask to what the mapping allows. */
109 static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
112 return mapping_gfp_mask(mapping) & gfp_mask;
116 * This is non-atomic. Only to be used before the mapping is activated.
117 * Probably needs a barrier...
119 static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
124 static inline bool mapping_thp_support(struct address_space *mapping)
126 return test_bit(AS_THP_SUPPORT, &mapping->flags);
129 static inline int filemap_nr_thps(struct address_space *mapping)
131 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
132 return atomic_read(&mapping->nr_thps);
138 static inline void filemap_nr_thps_inc(struct address_space *mapping)
140 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
141 if (!mapping_thp_support(mapping))
142 atomic_inc(&mapping->nr_thps);
148 static inline void filemap_nr_thps_dec(struct address_space *mapping)
150 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
151 if (!mapping_thp_support(mapping))
152 atomic_dec(&mapping->nr_thps);
158 void release_pages(struct page **pages, int nr);
161 * speculatively take a reference to a page.
162 * If the page is free (_refcount == 0), then _refcount is untouched, and 0
163 * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
165 * This function must be called inside the same rcu_read_lock() section as has
166 * been used to lookup the page in the pagecache radix-tree (or page table):
167 * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
169 * Unless an RCU grace period has passed, the count of all pages coming out
170 * of the allocator must be considered unstable. page_count may return higher
171 * than expected, and put_page must be able to do the right thing when the
172 * page has been finished with, no matter what it is subsequently allocated
173 * for (because put_page is what is used here to drop an invalid speculative
176 * This is the interesting part of the lockless pagecache (and lockless
177 * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
178 * has the following pattern:
179 * 1. find page in radix tree
180 * 2. conditionally increment refcount
181 * 3. check the page is still in pagecache (if no, goto 1)
183 * Remove-side that cares about stability of _refcount (eg. reclaim) has the
184 * following (with the i_pages lock held):
185 * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
186 * B. remove page from pagecache
189 * There are 2 critical interleavings that matter:
190 * - 2 runs before A: in this case, A sees elevated refcount and bails out
191 * - A runs before 2: in this case, 2 sees zero refcount and retries;
192 * subsequently, B will complete and 1 will find no page, causing the
193 * lookup to return NULL.
195 * It is possible that between 1 and 2, the page is removed then the exact same
196 * page is inserted into the same position in pagecache. That's OK: the
197 * old find_get_page using a lock could equally have run before or after
198 * such a re-insertion, depending on order that locks are granted.
200 * Lookups racing against pagecache insertion isn't a big problem: either 1
201 * will find the page or it will not. Likewise, the old find_get_page could run
202 * either before the insertion or afterwards, depending on timing.
204 static inline int __page_cache_add_speculative(struct page *page, int count)
206 #ifdef CONFIG_TINY_RCU
207 # ifdef CONFIG_PREEMPT_COUNT
208 VM_BUG_ON(!in_atomic() && !irqs_disabled());
211 * Preempt must be disabled here - we rely on rcu_read_lock doing
214 * Pagecache won't be truncated from interrupt context, so if we have
215 * found a page in the radix tree here, we have pinned its refcount by
216 * disabling preempt, and hence no need for the "speculative get" that
219 VM_BUG_ON_PAGE(page_count(page) == 0, page);
220 page_ref_add(page, count);
223 if (unlikely(!page_ref_add_unless(page, count, 0))) {
225 * Either the page has been freed, or will be freed.
226 * In either case, retry here and the caller should
227 * do the right thing (see comments above).
232 VM_BUG_ON_PAGE(PageTail(page), page);
237 static inline int page_cache_get_speculative(struct page *page)
239 return __page_cache_add_speculative(page, 1);
242 static inline int page_cache_add_speculative(struct page *page, int count)
244 return __page_cache_add_speculative(page, count);
248 * attach_page_private - Attach private data to a page.
249 * @page: Page to attach data to.
250 * @data: Data to attach to page.
252 * Attaching private data to a page increments the page's reference count.
253 * The data must be detached before the page will be freed.
255 static inline void attach_page_private(struct page *page, void *data)
258 set_page_private(page, (unsigned long)data);
259 SetPagePrivate(page);
263 * detach_page_private - Detach private data from a page.
264 * @page: Page to detach data from.
266 * Removes the data that was previously attached to the page and decrements
267 * the refcount on the page.
269 * Return: Data that was attached to the page.
271 static inline void *detach_page_private(struct page *page)
273 void *data = (void *)page_private(page);
275 if (!PagePrivate(page))
277 ClearPagePrivate(page);
278 set_page_private(page, 0);
285 extern struct page *__page_cache_alloc(gfp_t gfp);
287 static inline struct page *__page_cache_alloc(gfp_t gfp)
289 return alloc_pages(gfp, 0);
293 static inline struct page *page_cache_alloc(struct address_space *x)
295 return __page_cache_alloc(mapping_gfp_mask(x));
298 static inline gfp_t readahead_gfp_mask(struct address_space *x)
300 return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN;
303 typedef int filler_t(void *, struct page *);
305 pgoff_t page_cache_next_miss(struct address_space *mapping,
306 pgoff_t index, unsigned long max_scan);
307 pgoff_t page_cache_prev_miss(struct address_space *mapping,
308 pgoff_t index, unsigned long max_scan);
310 #define FGP_ACCESSED 0x00000001
311 #define FGP_LOCK 0x00000002
312 #define FGP_CREAT 0x00000004
313 #define FGP_WRITE 0x00000008
314 #define FGP_NOFS 0x00000010
315 #define FGP_NOWAIT 0x00000020
316 #define FGP_FOR_MMAP 0x00000040
317 #define FGP_HEAD 0x00000080
319 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
320 int fgp_flags, gfp_t cache_gfp_mask);
323 * find_get_page - find and get a page reference
324 * @mapping: the address_space to search
325 * @offset: the page index
327 * Looks up the page cache slot at @mapping & @offset. If there is a
328 * page cache page, it is returned with an increased refcount.
330 * Otherwise, %NULL is returned.
332 static inline struct page *find_get_page(struct address_space *mapping,
335 return pagecache_get_page(mapping, offset, 0, 0);
338 static inline struct page *find_get_page_flags(struct address_space *mapping,
339 pgoff_t offset, int fgp_flags)
341 return pagecache_get_page(mapping, offset, fgp_flags, 0);
345 * find_lock_page - locate, pin and lock a pagecache page
346 * @mapping: the address_space to search
347 * @offset: the page index
349 * Looks up the page cache entry at @mapping & @offset. If there is a
350 * page cache page, it is returned locked and with an increased
353 * Context: May sleep.
354 * Return: A struct page or %NULL if there is no page in the cache for this
357 static inline struct page *find_lock_page(struct address_space *mapping,
360 return pagecache_get_page(mapping, index, FGP_LOCK, 0);
364 * find_lock_head - Locate, pin and lock a pagecache page.
365 * @mapping: The address_space to search.
366 * @offset: The page index.
368 * Looks up the page cache entry at @mapping & @offset. If there is a
369 * page cache page, its head page is returned locked and with an increased
372 * Context: May sleep.
373 * Return: A struct page which is !PageTail, or %NULL if there is no page
374 * in the cache for this index.
376 static inline struct page *find_lock_head(struct address_space *mapping,
379 return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
383 * find_or_create_page - locate or add a pagecache page
384 * @mapping: the page's address_space
385 * @index: the page's index into the mapping
386 * @gfp_mask: page allocation mode
388 * Looks up the page cache slot at @mapping & @offset. If there is a
389 * page cache page, it is returned locked and with an increased
392 * If the page is not present, a new page is allocated using @gfp_mask
393 * and added to the page cache and the VM's LRU list. The page is
394 * returned locked and with an increased refcount.
396 * On memory exhaustion, %NULL is returned.
398 * find_or_create_page() may sleep, even if @gfp_flags specifies an
401 static inline struct page *find_or_create_page(struct address_space *mapping,
402 pgoff_t index, gfp_t gfp_mask)
404 return pagecache_get_page(mapping, index,
405 FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
410 * grab_cache_page_nowait - returns locked page at given index in given cache
411 * @mapping: target address_space
412 * @index: the page index
414 * Same as grab_cache_page(), but do not wait if the page is unavailable.
415 * This is intended for speculative data generators, where the data can
416 * be regenerated if the page couldn't be grabbed. This routine should
417 * be safe to call while holding the lock for another page.
419 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
420 * and deadlock against the caller's locked page.
422 static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
425 return pagecache_get_page(mapping, index,
426 FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
427 mapping_gfp_mask(mapping));
430 /* Does this page contain this index? */
431 static inline bool thp_contains(struct page *head, pgoff_t index)
433 /* HugeTLBfs indexes the page cache in units of hpage_size */
435 return head->index == index;
436 return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
440 * Given the page we found in the page cache, return the page corresponding
441 * to this index in the file
443 static inline struct page *find_subpage(struct page *head, pgoff_t index)
445 /* HugeTLBfs wants the head page regardless */
449 return head + (index & (thp_nr_pages(head) - 1));
452 unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
453 unsigned int nr_entries, struct page **entries,
455 unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
456 pgoff_t end, unsigned int nr_pages,
457 struct page **pages);
458 static inline unsigned find_get_pages(struct address_space *mapping,
459 pgoff_t *start, unsigned int nr_pages,
462 return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
465 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
466 unsigned int nr_pages, struct page **pages);
467 unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
468 pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
469 struct page **pages);
470 static inline unsigned find_get_pages_tag(struct address_space *mapping,
471 pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
474 return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
478 struct page *grab_cache_page_write_begin(struct address_space *mapping,
479 pgoff_t index, unsigned flags);
482 * Returns locked page at given index in given cache, creating it if needed.
484 static inline struct page *grab_cache_page(struct address_space *mapping,
487 return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
490 extern struct page * read_cache_page(struct address_space *mapping,
491 pgoff_t index, filler_t *filler, void *data);
492 extern struct page * read_cache_page_gfp(struct address_space *mapping,
493 pgoff_t index, gfp_t gfp_mask);
494 extern int read_cache_pages(struct address_space *mapping,
495 struct list_head *pages, filler_t *filler, void *data);
497 static inline struct page *read_mapping_page(struct address_space *mapping,
498 pgoff_t index, void *data)
500 return read_cache_page(mapping, index, NULL, data);
504 * Get index of the page with in radix-tree
505 * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
507 static inline pgoff_t page_to_index(struct page *page)
511 if (likely(!PageTransTail(page)))
515 * We don't initialize ->index for tail pages: calculate based on
518 pgoff = compound_head(page)->index;
519 pgoff += page - compound_head(page);
524 * Get the offset in PAGE_SIZE.
525 * (TODO: hugepage should have ->index in PAGE_SIZE)
527 static inline pgoff_t page_to_pgoff(struct page *page)
529 if (unlikely(PageHeadHuge(page)))
530 return page->index << compound_order(page);
532 return page_to_index(page);
536 * Return byte-offset into filesystem object for page.
538 static inline loff_t page_offset(struct page *page)
540 return ((loff_t)page->index) << PAGE_SHIFT;
543 static inline loff_t page_file_offset(struct page *page)
545 return ((loff_t)page_index(page)) << PAGE_SHIFT;
548 extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
549 unsigned long address);
551 static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
552 unsigned long address)
555 if (unlikely(is_vm_hugetlb_page(vma)))
556 return linear_hugepage_index(vma, address);
557 pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
558 pgoff += vma->vm_pgoff;
562 /* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */
563 struct wait_page_key {
569 struct wait_page_queue {
572 wait_queue_entry_t wait;
575 static inline bool wake_page_match(struct wait_page_queue *wait_page,
576 struct wait_page_key *key)
578 if (wait_page->page != key->page)
582 if (wait_page->bit_nr != key->bit_nr)
588 extern void __lock_page(struct page *page);
589 extern int __lock_page_killable(struct page *page);
590 extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
591 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
593 extern void unlock_page(struct page *page);
596 * Return true if the page was successfully locked
598 static inline int trylock_page(struct page *page)
600 page = compound_head(page);
601 return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
605 * lock_page may only be called if we have the page's inode pinned.
607 static inline void lock_page(struct page *page)
610 if (!trylock_page(page))
615 * lock_page_killable is like lock_page but can be interrupted by fatal
616 * signals. It returns 0 if it locked the page and -EINTR if it was
617 * killed while waiting.
619 static inline int lock_page_killable(struct page *page)
622 if (!trylock_page(page))
623 return __lock_page_killable(page);
628 * lock_page_async - Lock the page, unless this would block. If the page
629 * is already locked, then queue a callback when the page becomes unlocked.
630 * This callback can then retry the operation.
632 * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page
633 * was already locked and the callback defined in 'wait' was queued.
635 static inline int lock_page_async(struct page *page,
636 struct wait_page_queue *wait)
638 if (!trylock_page(page))
639 return __lock_page_async(page, wait);
644 * lock_page_or_retry - Lock the page, unless this would block and the
645 * caller indicated that it can handle a retry.
647 * Return value and mmap_lock implications depend on flags; see
648 * __lock_page_or_retry().
650 static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
654 return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
658 * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
659 * and should not be used directly.
661 extern void wait_on_page_bit(struct page *page, int bit_nr);
662 extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
665 * Wait for a page to be unlocked.
667 * This must be called with the caller "holding" the page,
668 * ie with increased "page->count" so that the page won't
669 * go away during the wait..
671 static inline void wait_on_page_locked(struct page *page)
673 if (PageLocked(page))
674 wait_on_page_bit(compound_head(page), PG_locked);
677 static inline int wait_on_page_locked_killable(struct page *page)
679 if (!PageLocked(page))
681 return wait_on_page_bit_killable(compound_head(page), PG_locked);
684 extern void put_and_wait_on_page_locked(struct page *page);
686 void wait_on_page_writeback(struct page *page);
687 extern void end_page_writeback(struct page *page);
688 void wait_for_stable_page(struct page *page);
690 void page_endio(struct page *page, bool is_write, int err);
693 * Add an arbitrary waiter to a page's wait queue
695 extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
698 * Fault everything in given userspace address range in.
700 static inline int fault_in_pages_writeable(char __user *uaddr, int size)
702 char __user *end = uaddr + size - 1;
704 if (unlikely(size == 0))
707 if (unlikely(uaddr > end))
710 * Writing zeroes into userspace here is OK, because we know that if
711 * the zero gets there, we'll be overwriting it.
714 if (unlikely(__put_user(0, uaddr) != 0))
717 } while (uaddr <= end);
719 /* Check whether the range spilled into the next page. */
720 if (((unsigned long)uaddr & PAGE_MASK) ==
721 ((unsigned long)end & PAGE_MASK))
722 return __put_user(0, end);
727 static inline int fault_in_pages_readable(const char __user *uaddr, int size)
730 const char __user *end = uaddr + size - 1;
732 if (unlikely(size == 0))
735 if (unlikely(uaddr > end))
739 if (unlikely(__get_user(c, uaddr) != 0))
742 } while (uaddr <= end);
744 /* Check whether the range spilled into the next page. */
745 if (((unsigned long)uaddr & PAGE_MASK) ==
746 ((unsigned long)end & PAGE_MASK)) {
747 return __get_user(c, end);
754 int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
755 pgoff_t index, gfp_t gfp_mask);
756 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
757 pgoff_t index, gfp_t gfp_mask);
758 extern void delete_from_page_cache(struct page *page);
759 extern void __delete_from_page_cache(struct page *page, void *shadow);
760 int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
761 void delete_from_page_cache_batch(struct address_space *mapping,
762 struct pagevec *pvec);
765 * Like add_to_page_cache_locked, but used to add newly allocated pages:
766 * the page is new, so we can just run __SetPageLocked() against it.
768 static inline int add_to_page_cache(struct page *page,
769 struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
773 __SetPageLocked(page);
774 error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
776 __ClearPageLocked(page);
781 * struct readahead_control - Describes a readahead request.
783 * A readahead request is for consecutive pages. Filesystems which
784 * implement the ->readahead method should call readahead_page() or
785 * readahead_page_batch() in a loop and attempt to start I/O against
786 * each page in the request.
788 * Most of the fields in this struct are private and should be accessed
789 * by the functions below.
791 * @file: The file, used primarily by network filesystems for authentication.
792 * May be NULL if invoked internally by the filesystem.
793 * @mapping: Readahead this filesystem object.
795 struct readahead_control {
797 struct address_space *mapping;
798 /* private: use the readahead_* accessors instead */
800 unsigned int _nr_pages;
801 unsigned int _batch_count;
804 #define DEFINE_READAHEAD(rac, f, m, i) \
805 struct readahead_control rac = { \
811 #define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
813 void page_cache_ra_unbounded(struct readahead_control *,
814 unsigned long nr_to_read, unsigned long lookahead_count);
815 void page_cache_sync_ra(struct readahead_control *, struct file_ra_state *,
816 unsigned long req_count);
817 void page_cache_async_ra(struct readahead_control *, struct file_ra_state *,
818 struct page *, unsigned long req_count);
821 * page_cache_sync_readahead - generic file readahead
822 * @mapping: address_space which holds the pagecache and I/O vectors
823 * @ra: file_ra_state which holds the readahead state
824 * @file: Used by the filesystem for authentication.
825 * @index: Index of first page to be read.
826 * @req_count: Total number of pages being read by the caller.
828 * page_cache_sync_readahead() should be called when a cache miss happened:
829 * it will submit the read. The readahead logic may decide to piggyback more
830 * pages onto the read request if access patterns suggest it will improve
834 void page_cache_sync_readahead(struct address_space *mapping,
835 struct file_ra_state *ra, struct file *file, pgoff_t index,
836 unsigned long req_count)
838 DEFINE_READAHEAD(ractl, file, mapping, index);
839 page_cache_sync_ra(&ractl, ra, req_count);
843 * page_cache_async_readahead - file readahead for marked pages
844 * @mapping: address_space which holds the pagecache and I/O vectors
845 * @ra: file_ra_state which holds the readahead state
846 * @file: Used by the filesystem for authentication.
847 * @page: The page at @index which triggered the readahead call.
848 * @index: Index of first page to be read.
849 * @req_count: Total number of pages being read by the caller.
851 * page_cache_async_readahead() should be called when a page is used which
852 * is marked as PageReadahead; this is a marker to suggest that the application
853 * has used up enough of the readahead window that we should start pulling in
857 void page_cache_async_readahead(struct address_space *mapping,
858 struct file_ra_state *ra, struct file *file,
859 struct page *page, pgoff_t index, unsigned long req_count)
861 DEFINE_READAHEAD(ractl, file, mapping, index);
862 page_cache_async_ra(&ractl, ra, page, req_count);
866 * readahead_page - Get the next page to read.
867 * @rac: The current readahead request.
869 * Context: The page is locked and has an elevated refcount. The caller
870 * should decreases the refcount once the page has been submitted for I/O
871 * and unlock the page once all I/O to that page has completed.
872 * Return: A pointer to the next page, or %NULL if we are done.
874 static inline struct page *readahead_page(struct readahead_control *rac)
878 BUG_ON(rac->_batch_count > rac->_nr_pages);
879 rac->_nr_pages -= rac->_batch_count;
880 rac->_index += rac->_batch_count;
882 if (!rac->_nr_pages) {
883 rac->_batch_count = 0;
887 page = xa_load(&rac->mapping->i_pages, rac->_index);
888 VM_BUG_ON_PAGE(!PageLocked(page), page);
889 rac->_batch_count = thp_nr_pages(page);
894 static inline unsigned int __readahead_batch(struct readahead_control *rac,
895 struct page **array, unsigned int array_sz)
898 XA_STATE(xas, &rac->mapping->i_pages, 0);
901 BUG_ON(rac->_batch_count > rac->_nr_pages);
902 rac->_nr_pages -= rac->_batch_count;
903 rac->_index += rac->_batch_count;
904 rac->_batch_count = 0;
906 xas_set(&xas, rac->_index);
908 xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
909 VM_BUG_ON_PAGE(!PageLocked(page), page);
910 VM_BUG_ON_PAGE(PageTail(page), page);
912 rac->_batch_count += thp_nr_pages(page);
915 * The page cache isn't using multi-index entries yet,
916 * so the xas cursor needs to be manually moved to the
917 * next index. This can be removed once the page cache
921 xas_set(&xas, rac->_index + rac->_batch_count);
932 * readahead_page_batch - Get a batch of pages to read.
933 * @rac: The current readahead request.
934 * @array: An array of pointers to struct page.
936 * Context: The pages are locked and have an elevated refcount. The caller
937 * should decreases the refcount once the page has been submitted for I/O
938 * and unlock the page once all I/O to that page has completed.
939 * Return: The number of pages placed in the array. 0 indicates the request
942 #define readahead_page_batch(rac, array) \
943 __readahead_batch(rac, array, ARRAY_SIZE(array))
946 * readahead_pos - The byte offset into the file of this readahead request.
947 * @rac: The readahead request.
949 static inline loff_t readahead_pos(struct readahead_control *rac)
951 return (loff_t)rac->_index * PAGE_SIZE;
955 * readahead_length - The number of bytes in this readahead request.
956 * @rac: The readahead request.
958 static inline loff_t readahead_length(struct readahead_control *rac)
960 return (loff_t)rac->_nr_pages * PAGE_SIZE;
964 * readahead_index - The index of the first page in this readahead request.
965 * @rac: The readahead request.
967 static inline pgoff_t readahead_index(struct readahead_control *rac)
973 * readahead_count - The number of pages in this readahead request.
974 * @rac: The readahead request.
976 static inline unsigned int readahead_count(struct readahead_control *rac)
978 return rac->_nr_pages;
981 static inline unsigned long dir_pages(struct inode *inode)
983 return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
988 * page_mkwrite_check_truncate - check if page was truncated
989 * @page: the page to check
990 * @inode: the inode to check the page against
992 * Returns the number of bytes in the page up to EOF,
993 * or -EFAULT if the page was truncated.
995 static inline int page_mkwrite_check_truncate(struct page *page,
998 loff_t size = i_size_read(inode);
999 pgoff_t index = size >> PAGE_SHIFT;
1000 int offset = offset_in_page(size);
1002 if (page->mapping != inode->i_mapping)
1005 /* page is wholly inside EOF */
1006 if (page->index < index)
1008 /* page is wholly past EOF */
1009 if (page->index > index || !offset)
1011 /* page is partially inside EOF */
1016 * i_blocks_per_page - How many blocks fit in this page.
1017 * @inode: The inode which contains the blocks.
1018 * @page: The page (head page if the page is a THP).
1020 * If the block size is larger than the size of this page, return zero.
1022 * Context: The caller should hold a refcount on the page to prevent it
1024 * Return: The number of filesystem blocks covered by this page.
1027 unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
1029 return thp_size(page) >> inode->i_blkbits;
1031 #endif /* _LINUX_PAGEMAP_H */