406 lines
14 KiB
C
Executable File
406 lines
14 KiB
C
Executable File
/*
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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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* This program/include file is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program/include file is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (in the main directory of the Linux-NTFS
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* distribution in the file COPYING); if not, write to the Free Software
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* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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* @nd: lookup nameidata
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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 %s in directory inode 0x%lx.",
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dent->d_name.name, 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 (likely(!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 (struct dentry *)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(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 @child_dent->d_inode->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 = child_dent->d_inode;
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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 (struct dentry *)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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