| /* 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> |
| |
| 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, |
| }; |
| |
| /** |
| * 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 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 int mapping_unevictable(struct address_space *mapping) |
| { |
| if (mapping) |
| return test_bit(AS_UNEVICTABLE, &mapping->flags); |
| return !!mapping; |
| } |
| |
| 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; |
| } |
| |
| 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 tree_lock held for write): |
| * 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 tree_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_get_speculative(struct page *page) |
| { |
| #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_inc(page); |
| |
| #else |
| if (unlikely(!get_page_unless_zero(page))) { |
| /* |
| * 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; |
| } |
| |
| /* |
| * Same as above, but add instead of inc (could just be merged) |
| */ |
| static inline int page_cache_add_speculative(struct page *page, int count) |
| { |
| VM_BUG_ON(in_interrupt()); |
| |
| #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) |
| # ifdef CONFIG_PREEMPT_COUNT |
| VM_BUG_ON(!in_atomic() && !irqs_disabled()); |
| # endif |
| VM_BUG_ON_PAGE(page_count(page) == 0, page); |
| page_ref_add(page, count); |
| |
| #else |
| if (unlikely(!page_ref_add_unless(page, count, 0))) |
| return 0; |
| #endif |
| VM_BUG_ON_PAGE(PageCompound(page) && page != compound_head(page), page); |
| |
| return 1; |
| } |
| |
| #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)); |
| } |
| |
| static inline struct page *page_cache_alloc_cold(struct address_space *x) |
| { |
| return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); |
| } |
| |
| static inline gfp_t readahead_gfp_mask(struct address_space *x) |
| { |
| return mapping_gfp_mask(x) | |
| __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN; |
| } |
| |
| typedef int filler_t(void *, struct page *); |
| |
| pgoff_t page_cache_next_hole(struct address_space *mapping, |
| pgoff_t index, unsigned long max_scan); |
| pgoff_t page_cache_prev_hole(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 |
| |
| 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 |
| * @offset: the page index |
| * |
| * 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. |
| * |
| * Otherwise, %NULL is returned. |
| * |
| * find_lock_page() may sleep. |
| */ |
| static inline struct page *find_lock_page(struct address_space *mapping, |
| pgoff_t offset) |
| { |
| return pagecache_get_page(mapping, offset, FGP_LOCK, 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 offset, gfp_t gfp_mask) |
| { |
| return pagecache_get_page(mapping, offset, |
| 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)); |
| } |
| |
| struct page *find_get_entry(struct address_space *mapping, pgoff_t offset); |
| struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset); |
| 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, int tag, unsigned int nr_pages, |
| struct page **pages); |
| static inline unsigned find_get_pages_tag(struct address_space *mapping, |
| pgoff_t *index, int tag, unsigned int nr_pages, |
| struct page **pages) |
| { |
| return find_get_pages_range_tag(mapping, index, (pgoff_t)-1, tag, |
| nr_pages, pages); |
| } |
| unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start, |
| int tag, unsigned int nr_entries, |
| struct page **entries, pgoff_t *indices); |
| |
| 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) |
| { |
| filler_t *filler = (filler_t *)mapping->a_ops->readpage; |
| return read_cache_page(mapping, index, filler, data); |
| } |
| |
| /* |
| * Get index of the page with in radix-tree |
| * (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; |
| } |
| |
| /* |
| * Get the offset in PAGE_SIZE. |
| * (TODO: hugepage should have ->index in PAGE_SIZE) |
| */ |
| static inline pgoff_t page_to_pgoff(struct page *page) |
| { |
| if (unlikely(PageHeadHuge(page))) |
| return page->index << compound_order(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 - vma->vm_start) >> PAGE_SHIFT; |
| pgoff += vma->vm_pgoff; |
| return pgoff; |
| } |
| |
| extern void __lock_page(struct page *page); |
| extern int __lock_page_killable(struct page *page); |
| extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
| unsigned int flags); |
| extern void unlock_page(struct page *page); |
| |
| 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 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 int lock_page_killable(struct page *page) |
| { |
| might_sleep(); |
| if (!trylock_page(page)) |
| return __lock_page_killable(page); |
| 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_sem implications depend on flags; see |
| * __lock_page_or_retry(). |
| */ |
| static inline 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 void wait_on_page_locked(struct page *page) |
| { |
| if (PageLocked(page)) |
| wait_on_page_bit(compound_head(page), PG_locked); |
| } |
| |
| static inline 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); |
| } |
| |
| /* |
| * Wait for a page to complete writeback |
| */ |
| static inline void wait_on_page_writeback(struct page *page) |
| { |
| if (PageWriteback(page)) |
| wait_on_page_bit(page, PG_writeback); |
| } |
| |
| 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; |
| } |
| |
| static inline unsigned long dir_pages(struct inode *inode) |
| { |
| return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >> |
| PAGE_SHIFT; |
| } |
| |
| #endif /* _LINUX_PAGEMAP_H */ |