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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _LINUX_PAGEMAP_H
- #define _LINUX_PAGEMAP_H
- /*
- * Copyright 1995 Linus Torvalds
- */
- #include <linux/mm.h>
- #include <linux/fs.h>
- #include <linux/list.h>
- #include <linux/highmem.h>
- #include <linux/compiler.h>
- #include <linux/uaccess.h>
- #include <linux/gfp.h>
- #include <linux/bitops.h>
- #include <linux/hardirq.h> /* for in_interrupt() */
- #include <linux/hugetlb_inline.h>
- #include <linux/sched/debug.h>
- struct pagevec;
- /*
- * Bits in mapping->flags.
- */
- enum mapping_flags {
- AS_EIO = 0, /* IO error on async write */
- AS_ENOSPC = 1, /* ENOSPC on async write */
- AS_MM_ALL_LOCKS = 2, /* under mm_take_all_locks() */
- AS_UNEVICTABLE = 3, /* e.g., ramdisk, SHM_LOCK */
- AS_EXITING = 4, /* final truncate in progress */
- /* writeback related tags are not used */
- AS_NO_WRITEBACK_TAGS = 5,
- AS_THP_SUPPORT = 6, /* THPs supported */
- };
- /**
- * mapping_set_error - record a writeback error in the address_space
- * @mapping: the mapping in which an error should be set
- * @error: the error to set in the mapping
- *
- * When writeback fails in some way, we must record that error so that
- * userspace can be informed when fsync and the like are called. We endeavor
- * to report errors on any file that was open at the time of the error. Some
- * internal callers also need to know when writeback errors have occurred.
- *
- * When a writeback error occurs, most filesystems will want to call
- * mapping_set_error to record the error in the mapping so that it can be
- * reported when the application calls fsync(2).
- */
- static inline void mapping_set_error(struct address_space *mapping, int error)
- {
- if (likely(!error))
- return;
- /* Record in wb_err for checkers using errseq_t based tracking */
- __filemap_set_wb_err(mapping, error);
- /* Record it in superblock */
- if (mapping->host)
- errseq_set(&mapping->host->i_sb->s_wb_err, error);
- /* Record it in flags for now, for legacy callers */
- if (error == -ENOSPC)
- set_bit(AS_ENOSPC, &mapping->flags);
- else
- set_bit(AS_EIO, &mapping->flags);
- }
- static inline void mapping_set_unevictable(struct address_space *mapping)
- {
- set_bit(AS_UNEVICTABLE, &mapping->flags);
- }
- static inline void mapping_clear_unevictable(struct address_space *mapping)
- {
- clear_bit(AS_UNEVICTABLE, &mapping->flags);
- }
- static inline bool mapping_unevictable(struct address_space *mapping)
- {
- return mapping && test_bit(AS_UNEVICTABLE, &mapping->flags);
- }
- static inline void mapping_set_exiting(struct address_space *mapping)
- {
- set_bit(AS_EXITING, &mapping->flags);
- }
- static inline int mapping_exiting(struct address_space *mapping)
- {
- return test_bit(AS_EXITING, &mapping->flags);
- }
- static inline void mapping_set_no_writeback_tags(struct address_space *mapping)
- {
- set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
- }
- static inline int mapping_use_writeback_tags(struct address_space *mapping)
- {
- return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags);
- }
- static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
- {
- return mapping->gfp_mask;
- }
- /* Restricts the given gfp_mask to what the mapping allows. */
- static inline gfp_t mapping_gfp_constraint(struct address_space *mapping,
- gfp_t gfp_mask)
- {
- return mapping_gfp_mask(mapping) & gfp_mask;
- }
- /*
- * This is non-atomic. Only to be used before the mapping is activated.
- * Probably needs a barrier...
- */
- static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
- {
- m->gfp_mask = mask;
- }
- static inline bool mapping_thp_support(struct address_space *mapping)
- {
- return test_bit(AS_THP_SUPPORT, &mapping->flags);
- }
- static inline int filemap_nr_thps(struct address_space *mapping)
- {
- #ifdef CONFIG_READ_ONLY_THP_FOR_FS
- return atomic_read(&mapping->nr_thps);
- #else
- return 0;
- #endif
- }
- static inline void filemap_nr_thps_inc(struct address_space *mapping)
- {
- #ifdef CONFIG_READ_ONLY_THP_FOR_FS
- if (!mapping_thp_support(mapping))
- atomic_inc(&mapping->nr_thps);
- #else
- WARN_ON_ONCE(1);
- #endif
- }
- static inline void filemap_nr_thps_dec(struct address_space *mapping)
- {
- #ifdef CONFIG_READ_ONLY_THP_FOR_FS
- if (!mapping_thp_support(mapping))
- atomic_dec(&mapping->nr_thps);
- #else
- WARN_ON_ONCE(1);
- #endif
- }
- void release_pages(struct page **pages, int nr);
- /*
- * speculatively take a reference to a page.
- * If the page is free (_refcount == 0), then _refcount is untouched, and 0
- * is returned. Otherwise, _refcount is incremented by 1 and 1 is returned.
- *
- * This function must be called inside the same rcu_read_lock() section as has
- * been used to lookup the page in the pagecache radix-tree (or page table):
- * this allows allocators to use a synchronize_rcu() to stabilize _refcount.
- *
- * Unless an RCU grace period has passed, the count of all pages coming out
- * of the allocator must be considered unstable. page_count may return higher
- * than expected, and put_page must be able to do the right thing when the
- * page has been finished with, no matter what it is subsequently allocated
- * for (because put_page is what is used here to drop an invalid speculative
- * reference).
- *
- * This is the interesting part of the lockless pagecache (and lockless
- * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
- * has the following pattern:
- * 1. find page in radix tree
- * 2. conditionally increment refcount
- * 3. check the page is still in pagecache (if no, goto 1)
- *
- * Remove-side that cares about stability of _refcount (eg. reclaim) has the
- * following (with the i_pages lock held):
- * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
- * B. remove page from pagecache
- * C. free the page
- *
- * There are 2 critical interleavings that matter:
- * - 2 runs before A: in this case, A sees elevated refcount and bails out
- * - A runs before 2: in this case, 2 sees zero refcount and retries;
- * subsequently, B will complete and 1 will find no page, causing the
- * lookup to return NULL.
- *
- * It is possible that between 1 and 2, the page is removed then the exact same
- * page is inserted into the same position in pagecache. That's OK: the
- * old find_get_page using a lock could equally have run before or after
- * such a re-insertion, depending on order that locks are granted.
- *
- * Lookups racing against pagecache insertion isn't a big problem: either 1
- * will find the page or it will not. Likewise, the old find_get_page could run
- * either before the insertion or afterwards, depending on timing.
- */
- static inline int __page_cache_add_speculative(struct page *page, int count)
- {
- #ifdef CONFIG_TINY_RCU
- # ifdef CONFIG_PREEMPT_COUNT
- VM_BUG_ON(!in_atomic() && !irqs_disabled());
- # endif
- /*
- * Preempt must be disabled here - we rely on rcu_read_lock doing
- * this for us.
- *
- * Pagecache won't be truncated from interrupt context, so if we have
- * found a page in the radix tree here, we have pinned its refcount by
- * disabling preempt, and hence no need for the "speculative get" that
- * SMP requires.
- */
- VM_BUG_ON_PAGE(page_count(page) == 0, page);
- page_ref_add(page, count);
- #else
- if (unlikely(!page_ref_add_unless(page, count, 0))) {
- /*
- * Either the page has been freed, or will be freed.
- * In either case, retry here and the caller should
- * do the right thing (see comments above).
- */
- return 0;
- }
- #endif
- VM_BUG_ON_PAGE(PageTail(page), page);
- return 1;
- }
- static inline int page_cache_get_speculative(struct page *page)
- {
- return __page_cache_add_speculative(page, 1);
- }
- static inline int page_cache_add_speculative(struct page *page, int count)
- {
- return __page_cache_add_speculative(page, count);
- }
- /**
- * attach_page_private - Attach private data to a page.
- * @page: Page to attach data to.
- * @data: Data to attach to page.
- *
- * Attaching private data to a page increments the page's reference count.
- * The data must be detached before the page will be freed.
- */
- static inline void attach_page_private(struct page *page, void *data)
- {
- get_page(page);
- set_page_private(page, (unsigned long)data);
- SetPagePrivate(page);
- }
- /**
- * detach_page_private - Detach private data from a page.
- * @page: Page to detach data from.
- *
- * Removes the data that was previously attached to the page and decrements
- * the refcount on the page.
- *
- * Return: Data that was attached to the page.
- */
- static inline void *detach_page_private(struct page *page)
- {
- void *data = (void *)page_private(page);
- if (!PagePrivate(page))
- return NULL;
- ClearPagePrivate(page);
- set_page_private(page, 0);
- put_page(page);
- return data;
- }
- #ifdef CONFIG_NUMA
- extern struct page *__page_cache_alloc(gfp_t gfp);
- #else
- static inline struct page *__page_cache_alloc(gfp_t gfp)
- {
- return alloc_pages(gfp, 0);
- }
- #endif
- static inline struct page *page_cache_alloc(struct address_space *x)
- {
- return __page_cache_alloc(mapping_gfp_mask(x));
- }
- gfp_t readahead_gfp_mask(struct address_space *x);
- typedef int filler_t(void *, struct page *);
- pgoff_t page_cache_next_miss(struct address_space *mapping,
- pgoff_t index, unsigned long max_scan);
- pgoff_t page_cache_prev_miss(struct address_space *mapping,
- pgoff_t index, unsigned long max_scan);
- #define FGP_ACCESSED 0x00000001
- #define FGP_LOCK 0x00000002
- #define FGP_CREAT 0x00000004
- #define FGP_WRITE 0x00000008
- #define FGP_NOFS 0x00000010
- #define FGP_NOWAIT 0x00000020
- #define FGP_FOR_MMAP 0x00000040
- #define FGP_HEAD 0x00000080
- struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
- int fgp_flags, gfp_t cache_gfp_mask);
- /**
- * find_get_page - find and get a page reference
- * @mapping: the address_space to search
- * @offset: the page index
- *
- * Looks up the page cache slot at @mapping & @offset. If there is a
- * page cache page, it is returned with an increased refcount.
- *
- * Otherwise, %NULL is returned.
- */
- static inline struct page *find_get_page(struct address_space *mapping,
- pgoff_t offset)
- {
- return pagecache_get_page(mapping, offset, 0, 0);
- }
- static inline struct page *find_get_page_flags(struct address_space *mapping,
- pgoff_t offset, int fgp_flags)
- {
- return pagecache_get_page(mapping, offset, fgp_flags, 0);
- }
- /**
- * find_lock_page - locate, pin and lock a pagecache page
- * @mapping: the address_space to search
- * @index: the page index
- *
- * Looks up the page cache entry at @mapping & @index. If there is a
- * page cache page, it is returned locked and with an increased
- * refcount.
- *
- * Context: May sleep.
- * Return: A struct page or %NULL if there is no page in the cache for this
- * index.
- */
- static inline struct page *find_lock_page(struct address_space *mapping,
- pgoff_t index)
- {
- return pagecache_get_page(mapping, index, FGP_LOCK, 0);
- }
- /**
- * find_lock_head - Locate, pin and lock a pagecache page.
- * @mapping: The address_space to search.
- * @index: The page index.
- *
- * Looks up the page cache entry at @mapping & @index. If there is a
- * page cache page, its head page is returned locked and with an increased
- * refcount.
- *
- * Context: May sleep.
- * Return: A struct page which is !PageTail, or %NULL if there is no page
- * in the cache for this index.
- */
- static inline struct page *find_lock_head(struct address_space *mapping,
- pgoff_t index)
- {
- return pagecache_get_page(mapping, index, FGP_LOCK | FGP_HEAD, 0);
- }
- /**
- * find_or_create_page - locate or add a pagecache page
- * @mapping: the page's address_space
- * @index: the page's index into the mapping
- * @gfp_mask: page allocation mode
- *
- * Looks up the page cache slot at @mapping & @offset. If there is a
- * page cache page, it is returned locked and with an increased
- * refcount.
- *
- * If the page is not present, a new page is allocated using @gfp_mask
- * and added to the page cache and the VM's LRU list. The page is
- * returned locked and with an increased refcount.
- *
- * On memory exhaustion, %NULL is returned.
- *
- * find_or_create_page() may sleep, even if @gfp_flags specifies an
- * atomic allocation!
- */
- static inline struct page *find_or_create_page(struct address_space *mapping,
- pgoff_t index, gfp_t gfp_mask)
- {
- return pagecache_get_page(mapping, index,
- FGP_LOCK|FGP_ACCESSED|FGP_CREAT,
- gfp_mask);
- }
- /**
- * grab_cache_page_nowait - returns locked page at given index in given cache
- * @mapping: target address_space
- * @index: the page index
- *
- * Same as grab_cache_page(), but do not wait if the page is unavailable.
- * This is intended for speculative data generators, where the data can
- * be regenerated if the page couldn't be grabbed. This routine should
- * be safe to call while holding the lock for another page.
- *
- * Clear __GFP_FS when allocating the page to avoid recursion into the fs
- * and deadlock against the caller's locked page.
- */
- static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
- pgoff_t index)
- {
- return pagecache_get_page(mapping, index,
- FGP_LOCK|FGP_CREAT|FGP_NOFS|FGP_NOWAIT,
- mapping_gfp_mask(mapping));
- }
- /* Does this page contain this index? */
- static inline bool thp_contains(struct page *head, pgoff_t index)
- {
- /* HugeTLBfs indexes the page cache in units of hpage_size */
- if (PageHuge(head))
- return head->index == index;
- return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
- }
- /*
- * Given the page we found in the page cache, return the page corresponding
- * to this index in the file
- */
- static inline struct page *find_subpage(struct page *head, pgoff_t index)
- {
- /* HugeTLBfs wants the head page regardless */
- if (PageHuge(head))
- return head;
- return head + (index & (thp_nr_pages(head) - 1));
- }
- unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
- unsigned int nr_entries, struct page **entries,
- pgoff_t *indices);
- unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
- pgoff_t end, unsigned int nr_pages,
- struct page **pages);
- static inline unsigned find_get_pages(struct address_space *mapping,
- pgoff_t *start, unsigned int nr_pages,
- struct page **pages)
- {
- return find_get_pages_range(mapping, start, (pgoff_t)-1, nr_pages,
- pages);
- }
- unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
- unsigned int nr_pages, struct page **pages);
- unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
- pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
- struct page **pages);
- static inline unsigned find_get_pages_tag(struct address_space *mapping,
- pgoff_t *index, xa_mark_t tag, unsigned int nr_pages,
- struct page **pages)
- {
- return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag,
- nr_pages, pages);
- }
- struct page *grab_cache_page_write_begin(struct address_space *mapping,
- pgoff_t index, unsigned flags);
- /*
- * Returns locked page at given index in given cache, creating it if needed.
- */
- static inline struct page *grab_cache_page(struct address_space *mapping,
- pgoff_t index)
- {
- return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
- }
- extern struct page * read_cache_page(struct address_space *mapping,
- pgoff_t index, filler_t *filler, void *data);
- extern struct page * read_cache_page_gfp(struct address_space *mapping,
- pgoff_t index, gfp_t gfp_mask);
- extern int read_cache_pages(struct address_space *mapping,
- struct list_head *pages, filler_t *filler, void *data);
- static inline struct page *read_mapping_page(struct address_space *mapping,
- pgoff_t index, void *data)
- {
- return read_cache_page(mapping, index, NULL, data);
- }
- /*
- * Get index of the page within radix-tree (but not for hugetlb pages).
- * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE)
- */
- static inline pgoff_t page_to_index(struct page *page)
- {
- pgoff_t pgoff;
- if (likely(!PageTransTail(page)))
- return page->index;
- /*
- * We don't initialize ->index for tail pages: calculate based on
- * head page
- */
- pgoff = compound_head(page)->index;
- pgoff += page - compound_head(page);
- return pgoff;
- }
- extern pgoff_t hugetlb_basepage_index(struct page *page);
- /*
- * Get the offset in PAGE_SIZE (even for hugetlb pages).
- * (TODO: hugetlb pages should have ->index in PAGE_SIZE)
- */
- static inline pgoff_t page_to_pgoff(struct page *page)
- {
- if (unlikely(PageHuge(page)))
- return hugetlb_basepage_index(page);
- return page_to_index(page);
- }
- /*
- * Return byte-offset into filesystem object for page.
- */
- static inline loff_t page_offset(struct page *page)
- {
- return ((loff_t)page->index) << PAGE_SHIFT;
- }
- static inline loff_t page_file_offset(struct page *page)
- {
- return ((loff_t)page_index(page)) << PAGE_SHIFT;
- }
- extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
- unsigned long address);
- static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
- unsigned long address)
- {
- pgoff_t pgoff;
- if (unlikely(is_vm_hugetlb_page(vma)))
- return linear_hugepage_index(vma, address);
- pgoff = (address - READ_ONCE(vma->vm_start)) >> PAGE_SHIFT;
- pgoff += READ_ONCE(vma->vm_pgoff);
- return pgoff;
- }
- struct wait_page_key {
- struct page *page;
- int bit_nr;
- int page_match;
- };
- struct wait_page_queue {
- struct page *page;
- int bit_nr;
- wait_queue_entry_t wait;
- };
- static inline bool wake_page_match(struct wait_page_queue *wait_page,
- struct wait_page_key *key)
- {
- if (wait_page->page != key->page)
- return false;
- key->page_match = 1;
- if (wait_page->bit_nr != key->bit_nr)
- return false;
- return true;
- }
- extern void __lock_page(struct page *page);
- extern int __lock_page_killable(struct page *page);
- extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
- extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
- unsigned int flags);
- extern void unlock_page(struct page *page);
- /*
- * Return true if the page was successfully locked
- */
- static inline int trylock_page(struct page *page)
- {
- page = compound_head(page);
- return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
- }
- /*
- * lock_page may only be called if we have the page's inode pinned.
- */
- static inline __sched void lock_page(struct page *page)
- {
- might_sleep();
- if (!trylock_page(page))
- __lock_page(page);
- }
- /*
- * lock_page_killable is like lock_page but can be interrupted by fatal
- * signals. It returns 0 if it locked the page and -EINTR if it was
- * killed while waiting.
- */
- static inline __sched int lock_page_killable(struct page *page)
- {
- might_sleep();
- if (!trylock_page(page))
- return __lock_page_killable(page);
- return 0;
- }
- /*
- * lock_page_async - Lock the page, unless this would block. If the page
- * is already locked, then queue a callback when the page becomes unlocked.
- * This callback can then retry the operation.
- *
- * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page
- * was already locked and the callback defined in 'wait' was queued.
- */
- static inline __sched int lock_page_async(struct page *page,
- struct wait_page_queue *wait)
- {
- if (!trylock_page(page))
- return __lock_page_async(page, wait);
- return 0;
- }
- /*
- * lock_page_or_retry - Lock the page, unless this would block and the
- * caller indicated that it can handle a retry.
- *
- * Return value and mmap_lock implications depend on flags; see
- * __lock_page_or_retry().
- */
- static inline __sched int lock_page_or_retry(struct page *page, struct mm_struct *mm,
- unsigned int flags)
- {
- might_sleep();
- return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
- }
- /*
- * This is exported only for wait_on_page_locked/wait_on_page_writeback, etc.,
- * and should not be used directly.
- */
- extern void wait_on_page_bit(struct page *page, int bit_nr);
- extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
- /*
- * Wait for a page to be unlocked.
- *
- * This must be called with the caller "holding" the page,
- * ie with increased "page->count" so that the page won't
- * go away during the wait..
- */
- static inline __sched void wait_on_page_locked(struct page *page)
- {
- if (PageLocked(page))
- wait_on_page_bit(compound_head(page), PG_locked);
- }
- static inline __sched int wait_on_page_locked_killable(struct page *page)
- {
- if (!PageLocked(page))
- return 0;
- return wait_on_page_bit_killable(compound_head(page), PG_locked);
- }
- extern void put_and_wait_on_page_locked(struct page *page);
- void wait_on_page_writeback(struct page *page);
- extern void end_page_writeback(struct page *page);
- void wait_for_stable_page(struct page *page);
- void page_endio(struct page *page, bool is_write, int err);
- /*
- * Add an arbitrary waiter to a page's wait queue
- */
- extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter);
- /*
- * Fault everything in given userspace address range in.
- */
- static inline int fault_in_pages_writeable(char __user *uaddr, int size)
- {
- char __user *end = uaddr + size - 1;
- if (unlikely(size == 0))
- return 0;
- if (unlikely(uaddr > end))
- return -EFAULT;
- /*
- * Writing zeroes into userspace here is OK, because we know that if
- * the zero gets there, we'll be overwriting it.
- */
- do {
- if (unlikely(__put_user(0, uaddr) != 0))
- return -EFAULT;
- uaddr += PAGE_SIZE;
- } while (uaddr <= end);
- /* Check whether the range spilled into the next page. */
- if (((unsigned long)uaddr & PAGE_MASK) ==
- ((unsigned long)end & PAGE_MASK))
- return __put_user(0, end);
- return 0;
- }
- static inline int fault_in_pages_readable(const char __user *uaddr, int size)
- {
- volatile char c;
- const char __user *end = uaddr + size - 1;
- if (unlikely(size == 0))
- return 0;
- if (unlikely(uaddr > end))
- return -EFAULT;
- do {
- if (unlikely(__get_user(c, uaddr) != 0))
- return -EFAULT;
- uaddr += PAGE_SIZE;
- } while (uaddr <= end);
- /* Check whether the range spilled into the next page. */
- if (((unsigned long)uaddr & PAGE_MASK) ==
- ((unsigned long)end & PAGE_MASK)) {
- return __get_user(c, end);
- }
- (void)c;
- return 0;
- }
- int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
- pgoff_t index, gfp_t gfp_mask);
- int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
- pgoff_t index, gfp_t gfp_mask);
- extern void delete_from_page_cache(struct page *page);
- extern void __delete_from_page_cache(struct page *page, void *shadow);
- int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
- void delete_from_page_cache_batch(struct address_space *mapping,
- struct pagevec *pvec);
- /*
- * Like add_to_page_cache_locked, but used to add newly allocated pages:
- * the page is new, so we can just run __SetPageLocked() against it.
- */
- static inline int add_to_page_cache(struct page *page,
- struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
- {
- int error;
- __SetPageLocked(page);
- error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
- if (unlikely(error))
- __ClearPageLocked(page);
- return error;
- }
- /**
- * struct readahead_control - Describes a readahead request.
- *
- * A readahead request is for consecutive pages. Filesystems which
- * implement the ->readahead method should call readahead_page() or
- * readahead_page_batch() in a loop and attempt to start I/O against
- * each page in the request.
- *
- * Most of the fields in this struct are private and should be accessed
- * by the functions below.
- *
- * @file: The file, used primarily by network filesystems for authentication.
- * May be NULL if invoked internally by the filesystem.
- * @mapping: Readahead this filesystem object.
- */
- struct readahead_control {
- struct file *file;
- struct address_space *mapping;
- /* private: use the readahead_* accessors instead */
- pgoff_t _index;
- unsigned int _nr_pages;
- unsigned int _batch_count;
- };
- #define DEFINE_READAHEAD(rac, f, m, i) \
- struct readahead_control rac = { \
- .file = f, \
- .mapping = m, \
- ._index = i, \
- }
- #define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE)
- void page_cache_ra_unbounded(struct readahead_control *,
- unsigned long nr_to_read, unsigned long lookahead_count);
- void page_cache_sync_ra(struct readahead_control *, struct file_ra_state *,
- unsigned long req_count);
- void page_cache_async_ra(struct readahead_control *, struct file_ra_state *,
- struct page *, unsigned long req_count);
- /**
- * page_cache_sync_readahead - generic file readahead
- * @mapping: address_space which holds the pagecache and I/O vectors
- * @ra: file_ra_state which holds the readahead state
- * @file: Used by the filesystem for authentication.
- * @index: Index of first page to be read.
- * @req_count: Total number of pages being read by the caller.
- *
- * page_cache_sync_readahead() should be called when a cache miss happened:
- * it will submit the read. The readahead logic may decide to piggyback more
- * pages onto the read request if access patterns suggest it will improve
- * performance.
- */
- static inline
- void page_cache_sync_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *file, pgoff_t index,
- unsigned long req_count)
- {
- DEFINE_READAHEAD(ractl, file, mapping, index);
- page_cache_sync_ra(&ractl, ra, req_count);
- }
- /**
- * page_cache_async_readahead - file readahead for marked pages
- * @mapping: address_space which holds the pagecache and I/O vectors
- * @ra: file_ra_state which holds the readahead state
- * @file: Used by the filesystem for authentication.
- * @page: The page at @index which triggered the readahead call.
- * @index: Index of first page to be read.
- * @req_count: Total number of pages being read by the caller.
- *
- * page_cache_async_readahead() should be called when a page is used which
- * is marked as PageReadahead; this is a marker to suggest that the application
- * has used up enough of the readahead window that we should start pulling in
- * more pages.
- */
- static inline
- void page_cache_async_readahead(struct address_space *mapping,
- struct file_ra_state *ra, struct file *file,
- struct page *page, pgoff_t index, unsigned long req_count)
- {
- DEFINE_READAHEAD(ractl, file, mapping, index);
- page_cache_async_ra(&ractl, ra, page, req_count);
- }
- /**
- * readahead_page - Get the next page to read.
- * @rac: The current readahead request.
- *
- * Context: The page is locked and has an elevated refcount. The caller
- * should decreases the refcount once the page has been submitted for I/O
- * and unlock the page once all I/O to that page has completed.
- * Return: A pointer to the next page, or %NULL if we are done.
- */
- static inline struct page *readahead_page(struct readahead_control *rac)
- {
- struct page *page;
- BUG_ON(rac->_batch_count > rac->_nr_pages);
- rac->_nr_pages -= rac->_batch_count;
- rac->_index += rac->_batch_count;
- if (!rac->_nr_pages) {
- rac->_batch_count = 0;
- return NULL;
- }
- page = xa_load(&rac->mapping->i_pages, rac->_index);
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- rac->_batch_count = thp_nr_pages(page);
- return page;
- }
- static inline unsigned int __readahead_batch(struct readahead_control *rac,
- struct page **array, unsigned int array_sz)
- {
- unsigned int i = 0;
- XA_STATE(xas, &rac->mapping->i_pages, 0);
- struct page *page;
- BUG_ON(rac->_batch_count > rac->_nr_pages);
- rac->_nr_pages -= rac->_batch_count;
- rac->_index += rac->_batch_count;
- rac->_batch_count = 0;
- xas_set(&xas, rac->_index);
- rcu_read_lock();
- xas_for_each(&xas, page, rac->_index + rac->_nr_pages - 1) {
- if (xas_retry(&xas, page))
- continue;
- VM_BUG_ON_PAGE(!PageLocked(page), page);
- VM_BUG_ON_PAGE(PageTail(page), page);
- array[i++] = page;
- rac->_batch_count += thp_nr_pages(page);
- /*
- * The page cache isn't using multi-index entries yet,
- * so the xas cursor needs to be manually moved to the
- * next index. This can be removed once the page cache
- * is converted.
- */
- if (PageHead(page))
- xas_set(&xas, rac->_index + rac->_batch_count);
- if (i == array_sz)
- break;
- }
- rcu_read_unlock();
- return i;
- }
- /**
- * readahead_page_batch - Get a batch of pages to read.
- * @rac: The current readahead request.
- * @array: An array of pointers to struct page.
- *
- * Context: The pages are locked and have an elevated refcount. The caller
- * should decreases the refcount once the page has been submitted for I/O
- * and unlock the page once all I/O to that page has completed.
- * Return: The number of pages placed in the array. 0 indicates the request
- * is complete.
- */
- #define readahead_page_batch(rac, array) \
- __readahead_batch(rac, array, ARRAY_SIZE(array))
- /**
- * readahead_pos - The byte offset into the file of this readahead request.
- * @rac: The readahead request.
- */
- static inline loff_t readahead_pos(struct readahead_control *rac)
- {
- return (loff_t)rac->_index * PAGE_SIZE;
- }
- /**
- * readahead_length - The number of bytes in this readahead request.
- * @rac: The readahead request.
- */
- static inline loff_t readahead_length(struct readahead_control *rac)
- {
- return (loff_t)rac->_nr_pages * PAGE_SIZE;
- }
- /**
- * readahead_index - The index of the first page in this readahead request.
- * @rac: The readahead request.
- */
- static inline pgoff_t readahead_index(struct readahead_control *rac)
- {
- return rac->_index;
- }
- /**
- * readahead_count - The number of pages in this readahead request.
- * @rac: The readahead request.
- */
- static inline unsigned int readahead_count(struct readahead_control *rac)
- {
- return rac->_nr_pages;
- }
- static inline unsigned long dir_pages(struct inode *inode)
- {
- return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >>
- PAGE_SHIFT;
- }
- /**
- * page_mkwrite_check_truncate - check if page was truncated
- * @page: the page to check
- * @inode: the inode to check the page against
- *
- * Returns the number of bytes in the page up to EOF,
- * or -EFAULT if the page was truncated.
- */
- static inline int page_mkwrite_check_truncate(struct page *page,
- struct inode *inode)
- {
- loff_t size = i_size_read(inode);
- pgoff_t index = size >> PAGE_SHIFT;
- int offset = offset_in_page(size);
- if (page->mapping != inode->i_mapping)
- return -EFAULT;
- /* page is wholly inside EOF */
- if (page->index < index)
- return PAGE_SIZE;
- /* page is wholly past EOF */
- if (page->index > index || !offset)
- return -EFAULT;
- /* page is partially inside EOF */
- return offset;
- }
- /**
- * i_blocks_per_page - How many blocks fit in this page.
- * @inode: The inode which contains the blocks.
- * @page: The page (head page if the page is a THP).
- *
- * If the block size is larger than the size of this page, return zero.
- *
- * Context: The caller should hold a refcount on the page to prevent it
- * from being split.
- * Return: The number of filesystem blocks covered by this page.
- */
- static inline
- unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
- {
- return thp_size(page) >> inode->i_blkbits;
- }
- #endif /* _LINUX_PAGEMAP_H */
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