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