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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 |
83 | * return value. If that evaluates to 'true', the negative error code can be |
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 | { |
89 | struct page *page = read_mapping_page(mapping, index, NULL); |
90 | |
91 | if (!IS_ERR(page)) { |
92 | kmap(page); |
93 | if (!PageError(page)) |
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 */ |
108 |
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