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391 lines
13 KiB
391 lines
13 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS |
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* project. |
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* |
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* Copyright (c) 2001-2006 Anton Altaparmakov |
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*/ |
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|
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#include <linux/dcache.h> |
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#include <linux/exportfs.h> |
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#include <linux/security.h> |
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#include <linux/slab.h> |
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#include "attrib.h" |
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#include "debug.h" |
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#include "dir.h" |
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#include "mft.h" |
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#include "ntfs.h" |
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/** |
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* ntfs_lookup - find the inode represented by a dentry in a directory inode |
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* @dir_ino: directory inode in which to look for the inode |
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* @dent: dentry representing the inode to look for |
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* @flags: lookup flags |
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* |
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* In short, ntfs_lookup() looks for the inode represented by the dentry @dent |
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* in the directory inode @dir_ino and if found attaches the inode to the |
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* dentry @dent. |
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* |
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* In more detail, the dentry @dent specifies which inode to look for by |
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* supplying the name of the inode in @dent->d_name.name. ntfs_lookup() |
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* converts the name to Unicode and walks the contents of the directory inode |
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* @dir_ino looking for the converted Unicode name. If the name is found in the |
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* directory, the corresponding inode is loaded by calling ntfs_iget() on its |
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* inode number and the inode is associated with the dentry @dent via a call to |
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* d_splice_alias(). |
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* |
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* If the name is not found in the directory, a NULL inode is inserted into the |
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* dentry @dent via a call to d_add(). The dentry is then termed a negative |
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* dentry. |
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* |
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* Only if an actual error occurs, do we return an error via ERR_PTR(). |
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* |
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* In order to handle the case insensitivity issues of NTFS with regards to the |
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* dcache and the dcache requiring only one dentry per directory, we deal with |
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* dentry aliases that only differ in case in ->ntfs_lookup() while maintaining |
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* a case sensitive dcache. This means that we get the full benefit of dcache |
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* speed when the file/directory is looked up with the same case as returned by |
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* ->ntfs_readdir() but that a lookup for any other case (or for the short file |
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* name) will not find anything in dcache and will enter ->ntfs_lookup() |
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* instead, where we search the directory for a fully matching file name |
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* (including case) and if that is not found, we search for a file name that |
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* matches with different case and if that has non-POSIX semantics we return |
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* that. We actually do only one search (case sensitive) and keep tabs on |
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* whether we have found a case insensitive match in the process. |
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* |
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* To simplify matters for us, we do not treat the short vs long filenames as |
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* two hard links but instead if the lookup matches a short filename, we |
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* return the dentry for the corresponding long filename instead. |
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* |
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* There are three cases we need to distinguish here: |
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* |
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* 1) @dent perfectly matches (i.e. including case) a directory entry with a |
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* file name in the WIN32 or POSIX namespaces. In this case |
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* ntfs_lookup_inode_by_name() will return with name set to NULL and we |
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* just d_splice_alias() @dent. |
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* 2) @dent matches (not including case) a directory entry with a file name in |
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* the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return |
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* with name set to point to a kmalloc()ed ntfs_name structure containing |
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* the properly cased little endian Unicode name. We convert the name to the |
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* current NLS code page, search if a dentry with this name already exists |
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* and if so return that instead of @dent. At this point things are |
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* complicated by the possibility of 'disconnected' dentries due to NFS |
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* which we deal with appropriately (see the code comments). The VFS will |
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* then destroy the old @dent and use the one we returned. If a dentry is |
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* not found, we allocate a new one, d_splice_alias() it, and return it as |
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* above. |
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* 3) @dent matches either perfectly or not (i.e. we don't care about case) a |
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* directory entry with a file name in the DOS namespace. In this case |
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* ntfs_lookup_inode_by_name() will return with name set to point to a |
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* kmalloc()ed ntfs_name structure containing the mft reference (cpu endian) |
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* of the inode. We use the mft reference to read the inode and to find the |
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* file name in the WIN32 namespace corresponding to the matched short file |
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* name. We then convert the name to the current NLS code page, and proceed |
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* searching for a dentry with this name, etc, as in case 2), above. |
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* |
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* Locking: Caller must hold i_mutex on the directory. |
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*/ |
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static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, |
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unsigned int flags) |
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{ |
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ntfs_volume *vol = NTFS_SB(dir_ino->i_sb); |
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struct inode *dent_inode; |
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ntfschar *uname; |
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ntfs_name *name = NULL; |
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MFT_REF mref; |
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unsigned long dent_ino; |
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int uname_len; |
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ntfs_debug("Looking up %pd in directory inode 0x%lx.", |
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dent, dir_ino->i_ino); |
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/* Convert the name of the dentry to Unicode. */ |
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uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len, |
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&uname); |
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if (uname_len < 0) { |
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if (uname_len != -ENAMETOOLONG) |
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ntfs_error(vol->sb, "Failed to convert name to " |
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"Unicode."); |
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return ERR_PTR(uname_len); |
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} |
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mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, |
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&name); |
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kmem_cache_free(ntfs_name_cache, uname); |
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if (!IS_ERR_MREF(mref)) { |
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dent_ino = MREF(mref); |
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ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); |
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dent_inode = ntfs_iget(vol->sb, dent_ino); |
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if (!IS_ERR(dent_inode)) { |
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/* Consistency check. */ |
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if (is_bad_inode(dent_inode) || MSEQNO(mref) == |
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NTFS_I(dent_inode)->seq_no || |
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dent_ino == FILE_MFT) { |
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/* Perfect WIN32/POSIX match. -- Case 1. */ |
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if (!name) { |
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ntfs_debug("Done. (Case 1.)"); |
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return d_splice_alias(dent_inode, dent); |
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} |
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/* |
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* We are too indented. Handle imperfect |
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* matches and short file names further below. |
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*/ |
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goto handle_name; |
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} |
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ntfs_error(vol->sb, "Found stale reference to inode " |
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"0x%lx (reference sequence number = " |
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"0x%x, inode sequence number = 0x%x), " |
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"returning -EIO. Run chkdsk.", |
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dent_ino, MSEQNO(mref), |
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NTFS_I(dent_inode)->seq_no); |
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iput(dent_inode); |
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dent_inode = ERR_PTR(-EIO); |
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} else |
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ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " |
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"error code %li.", dent_ino, |
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PTR_ERR(dent_inode)); |
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kfree(name); |
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/* Return the error code. */ |
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return ERR_CAST(dent_inode); |
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} |
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/* It is guaranteed that @name is no longer allocated at this point. */ |
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if (MREF_ERR(mref) == -ENOENT) { |
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ntfs_debug("Entry was not found, adding negative dentry."); |
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/* The dcache will handle negative entries. */ |
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d_add(dent, NULL); |
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ntfs_debug("Done."); |
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return NULL; |
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} |
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ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " |
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"code %i.", -MREF_ERR(mref)); |
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return ERR_PTR(MREF_ERR(mref)); |
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// TODO: Consider moving this lot to a separate function! (AIA) |
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handle_name: |
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{ |
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MFT_RECORD *m; |
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ntfs_attr_search_ctx *ctx; |
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ntfs_inode *ni = NTFS_I(dent_inode); |
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int err; |
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struct qstr nls_name; |
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nls_name.name = NULL; |
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if (name->type != FILE_NAME_DOS) { /* Case 2. */ |
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ntfs_debug("Case 2."); |
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nls_name.len = (unsigned)ntfs_ucstonls(vol, |
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(ntfschar*)&name->name, name->len, |
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(unsigned char**)&nls_name.name, 0); |
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kfree(name); |
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} else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */ |
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FILE_NAME_ATTR *fn; |
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ntfs_debug("Case 3."); |
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kfree(name); |
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/* Find the WIN32 name corresponding to the matched DOS name. */ |
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ni = NTFS_I(dent_inode); |
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m = map_mft_record(ni); |
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if (IS_ERR(m)) { |
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err = PTR_ERR(m); |
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m = NULL; |
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ctx = NULL; |
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goto err_out; |
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} |
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ctx = ntfs_attr_get_search_ctx(ni, m); |
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if (unlikely(!ctx)) { |
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err = -ENOMEM; |
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goto err_out; |
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} |
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do { |
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ATTR_RECORD *a; |
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u32 val_len; |
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err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0, |
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NULL, 0, ctx); |
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if (unlikely(err)) { |
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ntfs_error(vol->sb, "Inode corrupt: No WIN32 " |
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"namespace counterpart to DOS " |
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"file name. Run chkdsk."); |
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if (err == -ENOENT) |
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err = -EIO; |
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goto err_out; |
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} |
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/* Consistency checks. */ |
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a = ctx->attr; |
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if (a->non_resident || a->flags) |
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goto eio_err_out; |
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val_len = le32_to_cpu(a->data.resident.value_length); |
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if (le16_to_cpu(a->data.resident.value_offset) + |
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val_len > le32_to_cpu(a->length)) |
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goto eio_err_out; |
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fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu( |
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ctx->attr->data.resident.value_offset)); |
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if ((u32)(fn->file_name_length * sizeof(ntfschar) + |
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sizeof(FILE_NAME_ATTR)) > val_len) |
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goto eio_err_out; |
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} while (fn->file_name_type != FILE_NAME_WIN32); |
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/* Convert the found WIN32 name to current NLS code page. */ |
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nls_name.len = (unsigned)ntfs_ucstonls(vol, |
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(ntfschar*)&fn->file_name, fn->file_name_length, |
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(unsigned char**)&nls_name.name, 0); |
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ntfs_attr_put_search_ctx(ctx); |
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unmap_mft_record(ni); |
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} |
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m = NULL; |
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ctx = NULL; |
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/* Check if a conversion error occurred. */ |
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if ((signed)nls_name.len < 0) { |
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err = (signed)nls_name.len; |
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goto err_out; |
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} |
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nls_name.hash = full_name_hash(dent, nls_name.name, nls_name.len); |
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dent = d_add_ci(dent, dent_inode, &nls_name); |
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kfree(nls_name.name); |
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return dent; |
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eio_err_out: |
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ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); |
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err = -EIO; |
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err_out: |
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if (ctx) |
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ntfs_attr_put_search_ctx(ctx); |
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if (m) |
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unmap_mft_record(ni); |
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iput(dent_inode); |
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ntfs_error(vol->sb, "Failed, returning error code %i.", err); |
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return ERR_PTR(err); |
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} |
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} |
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/** |
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* Inode operations for directories. |
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*/ |
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const struct inode_operations ntfs_dir_inode_ops = { |
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.lookup = ntfs_lookup, /* VFS: Lookup directory. */ |
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}; |
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/** |
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* ntfs_get_parent - find the dentry of the parent of a given directory dentry |
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* @child_dent: dentry of the directory whose parent directory to find |
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* |
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* Find the dentry for the parent directory of the directory specified by the |
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* dentry @child_dent. This function is called from |
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* fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the |
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* default ->decode_fh() which is export_decode_fh() in the same file. |
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* |
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* The code is based on the ext3 ->get_parent() implementation found in |
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* fs/ext3/namei.c::ext3_get_parent(). |
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* |
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* Note: ntfs_get_parent() is called with @d_inode(child_dent)->i_mutex down. |
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* |
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* Return the dentry of the parent directory on success or the error code on |
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* error (IS_ERR() is true). |
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*/ |
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static struct dentry *ntfs_get_parent(struct dentry *child_dent) |
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{ |
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struct inode *vi = d_inode(child_dent); |
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ntfs_inode *ni = NTFS_I(vi); |
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MFT_RECORD *mrec; |
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ntfs_attr_search_ctx *ctx; |
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ATTR_RECORD *attr; |
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FILE_NAME_ATTR *fn; |
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unsigned long parent_ino; |
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int err; |
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ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); |
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/* Get the mft record of the inode belonging to the child dentry. */ |
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mrec = map_mft_record(ni); |
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if (IS_ERR(mrec)) |
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return ERR_CAST(mrec); |
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/* Find the first file name attribute in the mft record. */ |
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ctx = ntfs_attr_get_search_ctx(ni, mrec); |
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if (unlikely(!ctx)) { |
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unmap_mft_record(ni); |
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return ERR_PTR(-ENOMEM); |
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} |
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try_next: |
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err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, |
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0, ctx); |
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if (unlikely(err)) { |
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ntfs_attr_put_search_ctx(ctx); |
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unmap_mft_record(ni); |
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if (err == -ENOENT) |
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ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " |
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"file name attribute. Run chkdsk.", |
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vi->i_ino); |
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return ERR_PTR(err); |
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} |
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attr = ctx->attr; |
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if (unlikely(attr->non_resident)) |
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goto try_next; |
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fn = (FILE_NAME_ATTR *)((u8 *)attr + |
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le16_to_cpu(attr->data.resident.value_offset)); |
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if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > |
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(u8*)attr + le32_to_cpu(attr->length))) |
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goto try_next; |
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/* Get the inode number of the parent directory. */ |
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parent_ino = MREF_LE(fn->parent_directory); |
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/* Release the search context and the mft record of the child. */ |
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ntfs_attr_put_search_ctx(ctx); |
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unmap_mft_record(ni); |
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return d_obtain_alias(ntfs_iget(vi->i_sb, parent_ino)); |
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} |
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static struct inode *ntfs_nfs_get_inode(struct super_block *sb, |
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u64 ino, u32 generation) |
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{ |
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struct inode *inode; |
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inode = ntfs_iget(sb, ino); |
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if (!IS_ERR(inode)) { |
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if (is_bad_inode(inode) || inode->i_generation != generation) { |
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iput(inode); |
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inode = ERR_PTR(-ESTALE); |
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} |
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} |
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return inode; |
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} |
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static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid, |
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int fh_len, int fh_type) |
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{ |
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return generic_fh_to_dentry(sb, fid, fh_len, fh_type, |
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ntfs_nfs_get_inode); |
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} |
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static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid, |
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int fh_len, int fh_type) |
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{ |
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return generic_fh_to_parent(sb, fid, fh_len, fh_type, |
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ntfs_nfs_get_inode); |
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} |
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/** |
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* Export operations allowing NFS exporting of mounted NTFS partitions. |
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* |
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* We use the default ->encode_fh() for now. Note that they |
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* use 32 bits to store the inode number which is an unsigned long so on 64-bit |
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* architectures is usually 64 bits so it would all fail horribly on huge |
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* volumes. I guess we need to define our own encode and decode fh functions |
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* that store 64-bit inode numbers at some point but for now we will ignore the |
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* problem... |
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* |
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* We also use the default ->get_name() helper (used by ->decode_fh() via |
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* fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs |
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* independent. |
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* |
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* The default ->get_parent() just returns -EACCES so we have to provide our |
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* own and the default ->get_dentry() is incompatible with NTFS due to not |
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* allowing the inode number 0 which is used in NTFS for the system file $MFT |
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* and due to using iget() whereas NTFS needs ntfs_iget(). |
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*/ |
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const struct export_operations ntfs_export_ops = { |
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.get_parent = ntfs_get_parent, /* Find the parent of a given |
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directory. */ |
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.fh_to_dentry = ntfs_fh_to_dentry, |
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.fh_to_parent = ntfs_fh_to_parent, |
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};
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