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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)) { | |
92 | wait_on_page_locked(page); | |
93 | kmap(page); | |
94 | if (PageUptodate(page) && !PageError(page)) | |
95 | return page; | |
96 | ntfs_unmap_page(page); | |
97 | return ERR_PTR(-EIO); | |
98 | } | |
99 | return page; | |
100 | } | |
101 | ||
102 | #ifdef NTFS_RW | |
103 | ||
104 | extern void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs); | |
105 | ||
106 | #endif /* NTFS_RW */ | |
107 | ||
108 | #endif /* _LINUX_NTFS_AOPS_H */ |