/* SPDX-License-Identifier: GPL-2.0-or-later */ /** * aops.h - Defines for NTFS kernel address space operations and page cache * handling. Part of the Linux-NTFS project. * * Copyright (c) 2001-2004 Anton Altaparmakov * Copyright (c) 2002 Richard Russon */ #ifndef _LINUX_NTFS_AOPS_H #define _LINUX_NTFS_AOPS_H #include <linux/mm.h> #include <linux/highmem.h> #include <linux/pagemap.h> #include <linux/fs.h> #include "inode.h" /** * ntfs_unmap_page - release a page that was mapped using ntfs_map_page() * @page: the page to release * * Unpin, unmap and release a page that was obtained from ntfs_map_page(). */ static inline void ntfs_unmap_page(struct page *page) { kunmap(page); put_page(page); } /** * ntfs_map_page - map a page into accessible memory, reading it if necessary * @mapping: address space for which to obtain the page * @index: index into the page cache for @mapping of the page to map * * Read a page from the page cache of the address space @mapping at position * @index, where @index is in units of PAGE_SIZE, and not in bytes. * * If the page is not in memory it is loaded from disk first using the readpage * method defined in the address space operations of @mapping and the page is * added to the page cache of @mapping in the process. * * If the page belongs to an mst protected attribute and it is marked as such * in its ntfs inode (NInoMstProtected()) the mst fixups are applied but no * error checking is performed. This means the caller has to verify whether * the ntfs record(s) contained in the page are valid or not using one of the * ntfs_is_XXXX_record{,p}() macros, where XXXX is the record type you are * expecting to see. (For details of the macros, see fs/ntfs/layout.h.) * * If the page is in high memory it is mapped into memory directly addressible * by the kernel. * * Finally the page count is incremented, thus pinning the page into place. * * The above means that page_address(page) can be used on all pages obtained * with ntfs_map_page() to get the kernel virtual address of the page. * * When finished with the page, the caller has to call ntfs_unmap_page() to * unpin, unmap and release the page. * * Note this does not grant exclusive access. If such is desired, the caller * must provide it independently of the ntfs_{un}map_page() calls by using * a {rw_}semaphore or other means of serialization. A spin lock cannot be * used as ntfs_map_page() can block. * * The unlocked and uptodate page is returned on success or an encoded error * on failure. Caller has to test for error using the IS_ERR() macro on the * return value. If that evaluates to 'true', the negative error code can be * obtained using PTR_ERR() on the return value of ntfs_map_page(). */ static inline struct page *ntfs_map_page(struct address_space *mapping, unsigned long index) { struct page *page = read_mapping_page(mapping, index, NULL); if (!IS_ERR(page)) { kmap(page); if (!PageError(page)) return page; ntfs_unmap_page(page); return ERR_PTR(-EIO); } return page; } #ifdef NTFS_RW extern void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs); #endif /* NTFS_RW */ #endif /* _LINUX_NTFS_AOPS_H */