projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /** |
| 2 | * aops.h - Defines for NTFS kernel address space operations and page cache | |
| 3 | * handling. Part of the Linux-NTFS project. | |
| 4 | * | |
| 5 | * Copyright (c) 2001-2004 Anton Altaparmakov | |
| 6 | * Copyright (c) 2002 Richard Russon | |
| 7 | * | |
| 8 | * This program/include file is free software; you can redistribute it and/or | |
| 9 | * modify it under the terms of the GNU General Public License as published | |
| 10 | * by the Free Software Foundation; either version 2 of the License, or | |
| 11 | * (at your option) any later version. | |
| 12 | * | |
| 13 | * This program/include file is distributed in the hope that it will be | |
| 14 | * useful, but WITHOUT ANY WARRANTY; without even the implied warranty | |
| 15 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 16 | * GNU General Public License for more details. | |
| 17 | * | |
| 18 | * You should have received a copy of the GNU General Public License | |
| 19 | * along with this program (in the main directory of the Linux-NTFS | |
| 20 | * distribution in the file COPYING); if not, write to the Free Software | |
| 21 | * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 22 | */ | |
| 23 | ||
| 24 | #ifndef _LINUX_NTFS_AOPS_H | |
| 25 | #define _LINUX_NTFS_AOPS_H | |
| 26 | ||
| 27 | #include <linux/mm.h> | |
| 28 | #include <linux/highmem.h> | |
| 29 | #include <linux/pagemap.h> | |
| 30 | #include <linux/fs.h> | |
| 31 | ||
| 32 | #include "inode.h" | |
| 33 | ||
| 34 | /** | |
| 35 | * ntfs_unmap_page - release a page that was mapped using ntfs_map_page() | |
| 36 | * @page: the page to release | |
| 37 | * | |
| 38 | * Unpin, unmap and release a page that was obtained from ntfs_map_page(). | |
| 39 | */ | |
| 40 | static inline void ntfs_unmap_page(struct page *page) | |
| 41 | { | |
| 42 | kunmap(page); | |
| 43 | page_cache_release(page); | |
| 44 | } | |
| 45 | ||
| 46 | /** | |
| 47 | * ntfs_map_page - map a page into accessible memory, reading it if necessary | |
| 48 | * @mapping: address space for which to obtain the page | |
| 49 | * @index: index into the page cache for @mapping of the page to map | |
| 50 | * | |
| 51 | * Read a page from the page cache of the address space @mapping at position | |
| 52 | * @index, where @index is in units of PAGE_CACHE_SIZE, and not in bytes. | |
| 53 | * | |
| 54 | * If the page is not in memory it is loaded from disk first using the readpage | |
| 55 | * method defined in the address space operations of @mapping and the page is | |
| 56 | * added to the page cache of @mapping in the process. | |
| 57 | * | |
| 58 | * If the page belongs to an mst protected attribute and it is marked as such | |
| 59 | * in its ntfs inode (NInoMstProtected()) the mst fixups are applied but no | |
| 60 | * error checking is performed. This means the caller has to verify whether | |
| 61 | * the ntfs record(s) contained in the page are valid or not using one of the | |
| 62 | * ntfs_is_XXXX_record{,p}() macros, where XXXX is the record type you are | |
| 63 | * expecting to see. (For details of the macros, see fs/ntfs/layout.h.) | |
| 64 | * | |
| 65 | * If the page is in high memory it is mapped into memory directly addressible | |
| 66 | * by the kernel. | |
| 67 | * | |
| 68 | * Finally the page count is incremented, thus pinning the page into place. | |
| 69 | * | |
| 70 | * The above means that page_address(page) can be used on all pages obtained | |
| 71 | * with ntfs_map_page() to get the kernel virtual address of the page. | |
| 72 | * | |
| 73 | * When finished with the page, the caller has to call ntfs_unmap_page() to | |
| 74 | * unpin, unmap and release the page. | |
| 75 | * | |
| 76 | * Note this does not grant exclusive access. If such is desired, the caller | |
| 77 | * must provide it independently of the ntfs_{un}map_page() calls by using | |
| 78 | * a {rw_}semaphore or other means of serialization. A spin lock cannot be | |
| 79 | * used as ntfs_map_page() can block. | |
| 80 | * | |
| 81 | * The unlocked and uptodate page is returned on success or an encoded error | |
| 82 | * on failure. Caller has to test for error using the IS_ERR() macro on the | |
| c49c3111 | 83 | * return value. If that evaluates to 'true', the negative error code can be |
| 1da177e4 LT |
84 | * obtained using PTR_ERR() on the return value of ntfs_map_page(). |
| 85 | */ | |
| 86 | static inline struct page *ntfs_map_page(struct address_space *mapping, | |
| 87 | unsigned long index) | |
| 88 | { | |
| 090d2b18 | 89 | struct page *page = read_mapping_page(mapping, index, NULL); |
| 1da177e4 LT |
90 | |
| 91 | if (!IS_ERR(page)) { | |
| 1da177e4 | 92 | kmap(page); |
| 6fe6900e | 93 | if (!PageError(page)) |
| 1da177e4 LT |
94 | return page; |
| 95 | ntfs_unmap_page(page); | |
| 96 | return ERR_PTR(-EIO); | |
| 97 | } | |
| 98 | return page; | |
| 99 | } | |
| 100 | ||
| 101 | #ifdef NTFS_RW | |
| 102 | ||
| 103 | extern void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs); | |
| 104 | ||
| 105 | #endif /* NTFS_RW */ | |
| 106 | ||
| 107 | #endif /* _LINUX_NTFS_AOPS_H */ |