OwlCyberSecurity - MANAGER

Edit File: pagemap.h

/* 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 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); } #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 gfp_t readahead_gfp_mask(struct address_space *x) { return mapping_gfp_mask(x) | __GFP_NORETRY | __GFP_NOWARN; } 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 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)); } static inline struct page *find_subpage(struct page *page, pgoff_t offset) { if (PageHuge(page)) return page; VM_BUG_ON_PAGE(PageTail(page), page); return page + (offset & (compound_nr(page) - 1)); } 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, 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 - 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); /* * 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 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); } 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; } static inline unsigned long dir_pages(struct inode *inode) { return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT; } #endif /* _LINUX_PAGEMAP_H */