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Diffstat (limited to 'fs/ntfs/aops.h')
| -rw-r--r-- | fs/ntfs/aops.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/fs/ntfs/aops.h b/fs/ntfs/aops.h new file mode 100644 index 00000000000..3b74e66ca2f --- /dev/null +++ b/fs/ntfs/aops.h @@ -0,0 +1,109 @@ +/** + * 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 + * + * This program/include file is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as published + * by the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program/include file is distributed in the hope that it will be + * useful, but WITHOUT ANY WARRANTY; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program (in the main directory of the Linux-NTFS + * distribution in the file COPYING); if not, write to the Free Software + * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#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); + page_cache_release(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_CACHE_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_cache_page(mapping, index, + (filler_t*)mapping->a_ops->readpage, NULL); + + if (!IS_ERR(page)) { + wait_on_page_locked(page); + kmap(page); + if (PageUptodate(page) && !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 */ |