FreeBSD/Linux Kernel Cross Reference
sys/fs/ntfs/dir.c

     /**
      * dir.c - NTFS kernel directory operations. Part of the Linux-NTFS project.
      *
      * Copyright (c) 2001-2007 Anton Altaparmakov
      * Copyright (c) 2002 Richard Russon
      *
      * This program/include file is free software; you can redistribute it and/or
      * modify it under the terms of the GNU General Public License as published
      * by the Free Software Foundation; either version 2 of the License, or
     * (at your option) any later version.
     *
     * This program/include file is distributed in the hope that it will be
     * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
     * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     * You should have received a copy of the GNU General Public License
     * along with this program (in the main directory of the Linux-NTFS
     * distribution in the file COPYING); if not, write to the Free Software
     * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     */
    
    #include <linux/buffer_head.h>
    #include <linux/slab.h>
    
    #include "dir.h"
    #include "aops.h"
    #include "attrib.h"
    #include "mft.h"
    #include "debug.h"
    #include "ntfs.h"
    
    /**
     * The little endian Unicode string $I30 as a global constant.
     */
    ntfschar I30[5] = { cpu_to_le16('$'), cpu_to_le16('I'),
                    cpu_to_le16('3'),       cpu_to_le16(''), 0 };
    
    /**
     * ntfs_lookup_inode_by_name - find an inode in a directory given its name
     * @dir_ni:     ntfs inode of the directory in which to search for the name
     * @uname:      Unicode name for which to search in the directory
     * @uname_len:  length of the name @uname in Unicode characters
     * @res:        return the found file name if necessary (see below)
     *
     * Look for an inode with name @uname in the directory with inode @dir_ni.
     * ntfs_lookup_inode_by_name() walks the contents of the directory looking for
     * the Unicode name. If the name is found in the directory, the corresponding
     * inode number (>= 0) is returned as a mft reference in cpu format, i.e. it
     * is a 64-bit number containing the sequence number.
     *
     * On error, a negative value is returned corresponding to the error code. In
     * particular if the inode is not found -ENOENT is returned. Note that you
     * can't just check the return value for being negative, you have to check the
     * inode number for being negative which you can extract using MREC(return
     * value).
     *
     * Note, @uname_len does not include the (optional) terminating NULL character.
     *
     * Note, we look for a case sensitive match first but we also look for a case
     * insensitive match at the same time. If we find a case insensitive match, we
     * save that for the case that we don't find an exact match, where we return
     * the case insensitive match and setup @res (which we allocate!) with the mft
     * reference, the file name type, length and with a copy of the little endian
     * Unicode file name itself. If we match a file name which is in the DOS name
     * space, we only return the mft reference and file name type in @res.
     * ntfs_lookup() then uses this to find the long file name in the inode itself.
     * This is to avoid polluting the dcache with short file names. We want them to
     * work but we don't care for how quickly one can access them. This also fixes
     * the dcache aliasing issues.
     *
     * Locking:  - Caller must hold i_mutex on the directory.
     *           - Each page cache page in the index allocation mapping must be
     *             locked whilst being accessed otherwise we may find a corrupt
     *             page due to it being under ->writepage at the moment which
     *             applies the mst protection fixups before writing out and then
     *             removes them again after the write is complete after which it 
     *             unlocks the page.
     */
    MFT_REF ntfs_lookup_inode_by_name(ntfs_inode *dir_ni, const ntfschar *uname,
                    const int uname_len, ntfs_name **res)
    {
            ntfs_volume *vol = dir_ni->vol;
            struct super_block *sb = vol->sb;
            MFT_RECORD *m;
            INDEX_ROOT *ir;
            INDEX_ENTRY *ie;
            INDEX_ALLOCATION *ia;
            u8 *index_end;
            u64 mref;
            ntfs_attr_search_ctx *ctx;
            int err, rc;
            VCN vcn, old_vcn;
            struct address_space *ia_mapping;
            struct page *page;
            u8 *kaddr;
            ntfs_name *name = NULL;
    
            BUG_ON(!S_ISDIR(VFS_I(dir_ni)->i_mode));
           BUG_ON(NInoAttr(dir_ni));
           /* Get hold of the mft record for the directory. */
           m = map_mft_record(dir_ni);
           if (IS_ERR(m)) {
                   ntfs_error(sb, "map_mft_record() failed with error code %ld.",
                                   -PTR_ERR(m));
                   return ERR_MREF(PTR_ERR(m));
           }
           ctx = ntfs_attr_get_search_ctx(dir_ni, m);
           if (unlikely(!ctx)) {
                   err = -ENOMEM;
                   goto err_out;
           }
           /* Find the index root attribute in the mft record. */
           err = ntfs_attr_lookup(AT_INDEX_ROOT, I30, 4, CASE_SENSITIVE, 0, NULL,
                           0, ctx);
           if (unlikely(err)) {
                   if (err == -ENOENT) {
                           ntfs_error(sb, "Index root attribute missing in "
                                           "directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           err = -EIO;
                   }
                   goto err_out;
           }
           /* Get to the index root value (it's been verified in read_inode). */
           ir = (INDEX_ROOT*)((u8*)ctx->attr +
                           le16_to_cpu(ctx->attr->data.resident.value_offset));
           index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
           /* The first index entry. */
           ie = (INDEX_ENTRY*)((u8*)&ir->index +
                           le32_to_cpu(ir->index.entries_offset));
           /*
            * Loop until we exceed valid memory (corruption case) or until we
            * reach the last entry.
            */
           for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                   /* Bounds checks. */
                   if ((u8*)ie < (u8*)ctx->mrec || (u8*)ie +
                                   sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                   (u8*)ie + le16_to_cpu(ie->key_length) >
                                   index_end)
                           goto dir_err_out;
                   /*
                    * The last entry cannot contain a name. It can however contain
                    * a pointer to a child node in the B+tree so we just break out.
                    */
                   if (ie->flags & INDEX_ENTRY_END)
                           break;
                   /*
                    * We perform a case sensitive comparison and if that matches
                    * we are done and return the mft reference of the inode (i.e.
                    * the inode number together with the sequence number for
                    * consistency checking). We convert it to cpu format before
                    * returning.
                    */
                   if (ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len)) {
   found_it:
                           /*
                            * We have a perfect match, so we don't need to care
                            * about having matched imperfectly before, so we can
                            * free name and set *res to NULL.
                            * However, if the perfect match is a short file name,
                            * we need to signal this through *res, so that
                            * ntfs_lookup() can fix dcache aliasing issues.
                            * As an optimization we just reuse an existing
                            * allocation of *res.
                            */
                           if (ie->key.file_name.file_name_type == FILE_NAME_DOS) {
                                   if (!name) {
                                           name = kmalloc(sizeof(ntfs_name),
                                                           GFP_NOFS);
                                           if (!name) {
                                                   err = -ENOMEM;
                                                   goto err_out;
                                           }
                                   }
                                   name->mref = le64_to_cpu(
                                                   ie->data.dir.indexed_file);
                                   name->type = FILE_NAME_DOS;
                                   name->len = 0;
                                   *res = name;
                           } else {
                                   kfree(name);
                                   *res = NULL;
                           }
                           mref = le64_to_cpu(ie->data.dir.indexed_file);
                           ntfs_attr_put_search_ctx(ctx);
                           unmap_mft_record(dir_ni);
                           return mref;
                   }
                   /*
                    * For a case insensitive mount, we also perform a case
                    * insensitive comparison (provided the file name is not in the
                    * POSIX namespace). If the comparison matches, and the name is
                    * in the WIN32 namespace, we cache the filename in *res so
                    * that the caller, ntfs_lookup(), can work on it. If the
                    * comparison matches, and the name is in the DOS namespace, we
                    * only cache the mft reference and the file name type (we set
                    * the name length to zero for simplicity).
                    */
                   if (!NVolCaseSensitive(vol) &&
                                   ie->key.file_name.file_name_type &&
                                   ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len)) {
                           int name_size = sizeof(ntfs_name);
                           u8 type = ie->key.file_name.file_name_type;
                           u8 len = ie->key.file_name.file_name_length;
   
                           /* Only one case insensitive matching name allowed. */
                           if (name) {
                                   ntfs_error(sb, "Found already allocated name "
                                                   "in phase 1. Please run chkdsk "
                                                   "and if that doesn't find any "
                                                   "errors please report you saw "
                                                   "this message to "
                                                   "linux-ntfs-dev@lists."
                                                   "sourceforge.net.");
                                   goto dir_err_out;
                           }
   
                           if (type != FILE_NAME_DOS)
                                   name_size += len * sizeof(ntfschar);
                           name = kmalloc(name_size, GFP_NOFS);
                           if (!name) {
                                   err = -ENOMEM;
                                   goto err_out;
                           }
                           name->mref = le64_to_cpu(ie->data.dir.indexed_file);
                           name->type = type;
                           if (type != FILE_NAME_DOS) {
                                   name->len = len;
                                   memcpy(name->name, ie->key.file_name.file_name,
                                                   len * sizeof(ntfschar));
                           } else
                                   name->len = 0;
                           *res = name;
                   }
                   /*
                    * Not a perfect match, need to do full blown collation so we
                    * know which way in the B+tree we have to go.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len);
                   /*
                    * If uname collates before the name of the current entry, there
                    * is definitely no such name in this index but we might need to
                    * descend into the B+tree so we just break out of the loop.
                    */
                   if (rc == -1)
                           break;
                   /* The names are not equal, continue the search. */
                   if (rc)
                           continue;
                   /*
                    * Names match with case insensitive comparison, now try the
                    * case sensitive comparison, which is required for proper
                    * collation.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len);
                   if (rc == -1)
                           break;
                   if (rc)
                           continue;
                   /*
                    * Perfect match, this will never happen as the
                    * ntfs_are_names_equal() call will have gotten a match but we
                    * still treat it correctly.
                    */
                   goto found_it;
           }
           /*
            * We have finished with this index without success. Check for the
            * presence of a child node and if not present return -ENOENT, unless
            * we have got a matching name cached in name in which case return the
            * mft reference associated with it.
            */
           if (!(ie->flags & INDEX_ENTRY_NODE)) {
                   if (name) {
                           ntfs_attr_put_search_ctx(ctx);
                           unmap_mft_record(dir_ni);
                           return name->mref;
                   }
                   ntfs_debug("Entry not found.");
                   err = -ENOENT;
                   goto err_out;
           } /* Child node present, descend into it. */
           /* Consistency check: Verify that an index allocation exists. */
           if (!NInoIndexAllocPresent(dir_ni)) {
                   ntfs_error(sb, "No index allocation attribute but index entry "
                                   "requires one. Directory inode 0x%lx is "
                                   "corrupt or driver bug.", dir_ni->mft_no);
                   goto err_out;
           }
           /* Get the starting vcn of the index_block holding the child node. */
           vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
           ia_mapping = VFS_I(dir_ni)->i_mapping;
           /*
            * We are done with the index root and the mft record. Release them,
            * otherwise we deadlock with ntfs_map_page().
            */
           ntfs_attr_put_search_ctx(ctx);
           unmap_mft_record(dir_ni);
           m = NULL;
           ctx = NULL;
   descend_into_child_node:
           /*
            * Convert vcn to index into the index allocation attribute in units
            * of PAGE_CACHE_SIZE and map the page cache page, reading it from
            * disk if necessary.
            */
           page = ntfs_map_page(ia_mapping, vcn <<
                           dir_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
           if (IS_ERR(page)) {
                   ntfs_error(sb, "Failed to map directory index page, error %ld.",
                                   -PTR_ERR(page));
                   err = PTR_ERR(page);
                   goto err_out;
           }
           lock_page(page);
           kaddr = (u8*)page_address(page);
   fast_descend_into_child_node:
           /* Get to the index allocation block. */
           ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
                           dir_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
           /* Bounds checks. */
           if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
                   ntfs_error(sb, "Out of bounds check failed. Corrupt directory "
                                   "inode 0x%lx or driver bug.", dir_ni->mft_no);
                   goto unm_err_out;
           }
           /* Catch multi sector transfer fixup errors. */
           if (unlikely(!ntfs_is_indx_record(ia->magic))) {
                   ntfs_error(sb, "Directory index record with vcn 0x%llx is "
                                   "corrupt.  Corrupt inode 0x%lx.  Run chkdsk.",
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
                   ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
                                   "different from expected VCN (0x%llx). "
                                   "Directory inode 0x%lx is corrupt or driver "
                                   "bug.", (unsigned long long)
                                   sle64_to_cpu(ia->index_block_vcn),
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
                           dir_ni->itype.index.block_size) {
                   ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                   "0x%lx has a size (%u) differing from the "
                                   "directory specified size (%u). Directory "
                                   "inode is corrupt or driver bug.",
                                   (unsigned long long)vcn, dir_ni->mft_no,
                                   le32_to_cpu(ia->index.allocated_size) + 0x18,
                                   dir_ni->itype.index.block_size);
                   goto unm_err_out;
           }
           index_end = (u8*)ia + dir_ni->itype.index.block_size;
           if (index_end > kaddr + PAGE_CACHE_SIZE) {
                   ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                   "0x%lx crosses page boundary. Impossible! "
                                   "Cannot access! This is probably a bug in the "
                                   "driver.", (unsigned long long)vcn,
                                   dir_ni->mft_no);
                   goto unm_err_out;
           }
           index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
           if (index_end > (u8*)ia + dir_ni->itype.index.block_size) {
                   ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of directory "
                                   "inode 0x%lx exceeds maximum size.",
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           /* The first index entry. */
           ie = (INDEX_ENTRY*)((u8*)&ia->index +
                           le32_to_cpu(ia->index.entries_offset));
           /*
            * Iterate similar to above big loop but applied to index buffer, thus
            * loop until we exceed valid memory (corruption case) or until we
            * reach the last entry.
            */
           for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                   /* Bounds check. */
                   if ((u8*)ie < (u8*)ia || (u8*)ie +
                                   sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                   (u8*)ie + le16_to_cpu(ie->key_length) >
                                   index_end) {
                           ntfs_error(sb, "Index entry out of bounds in "
                                           "directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           goto unm_err_out;
                   }
                   /*
                    * The last entry cannot contain a name. It can however contain
                    * a pointer to a child node in the B+tree so we just break out.
                    */
                   if (ie->flags & INDEX_ENTRY_END)
                           break;
                   /*
                    * We perform a case sensitive comparison and if that matches
                    * we are done and return the mft reference of the inode (i.e.
                    * the inode number together with the sequence number for
                    * consistency checking). We convert it to cpu format before
                    * returning.
                    */
                   if (ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len)) {
   found_it2:
                           /*
                            * We have a perfect match, so we don't need to care
                            * about having matched imperfectly before, so we can
                            * free name and set *res to NULL.
                            * However, if the perfect match is a short file name,
                            * we need to signal this through *res, so that
                            * ntfs_lookup() can fix dcache aliasing issues.
                            * As an optimization we just reuse an existing
                            * allocation of *res.
                            */
                           if (ie->key.file_name.file_name_type == FILE_NAME_DOS) {
                                   if (!name) {
                                           name = kmalloc(sizeof(ntfs_name),
                                                           GFP_NOFS);
                                           if (!name) {
                                                   err = -ENOMEM;
                                                   goto unm_err_out;
                                           }
                                   }
                                   name->mref = le64_to_cpu(
                                                   ie->data.dir.indexed_file);
                                   name->type = FILE_NAME_DOS;
                                   name->len = 0;
                                   *res = name;
                           } else {
                                   kfree(name);
                                   *res = NULL;
                           }
                           mref = le64_to_cpu(ie->data.dir.indexed_file);
                           unlock_page(page);
                           ntfs_unmap_page(page);
                           return mref;
                   }
                   /*
                    * For a case insensitive mount, we also perform a case
                    * insensitive comparison (provided the file name is not in the
                    * POSIX namespace). If the comparison matches, and the name is
                    * in the WIN32 namespace, we cache the filename in *res so
                    * that the caller, ntfs_lookup(), can work on it. If the
                    * comparison matches, and the name is in the DOS namespace, we
                    * only cache the mft reference and the file name type (we set
                    * the name length to zero for simplicity).
                    */
                   if (!NVolCaseSensitive(vol) &&
                                   ie->key.file_name.file_name_type &&
                                   ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len)) {
                           int name_size = sizeof(ntfs_name);
                           u8 type = ie->key.file_name.file_name_type;
                           u8 len = ie->key.file_name.file_name_length;
   
                           /* Only one case insensitive matching name allowed. */
                           if (name) {
                                   ntfs_error(sb, "Found already allocated name "
                                                   "in phase 2. Please run chkdsk "
                                                   "and if that doesn't find any "
                                                   "errors please report you saw "
                                                   "this message to "
                                                   "linux-ntfs-dev@lists."
                                                   "sourceforge.net.");
                                   unlock_page(page);
                                   ntfs_unmap_page(page);
                                   goto dir_err_out;
                           }
   
                           if (type != FILE_NAME_DOS)
                                   name_size += len * sizeof(ntfschar);
                           name = kmalloc(name_size, GFP_NOFS);
                           if (!name) {
                                   err = -ENOMEM;
                                   goto unm_err_out;
                           }
                           name->mref = le64_to_cpu(ie->data.dir.indexed_file);
                           name->type = type;
                           if (type != FILE_NAME_DOS) {
                                   name->len = len;
                                   memcpy(name->name, ie->key.file_name.file_name,
                                                   len * sizeof(ntfschar));
                           } else
                                   name->len = 0;
                           *res = name;
                   }
                   /*
                    * Not a perfect match, need to do full blown collation so we
                    * know which way in the B+tree we have to go.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len);
                   /*
                    * If uname collates before the name of the current entry, there
                    * is definitely no such name in this index but we might need to
                    * descend into the B+tree so we just break out of the loop.
                    */
                   if (rc == -1)
                           break;
                   /* The names are not equal, continue the search. */
                   if (rc)
                           continue;
                   /*
                    * Names match with case insensitive comparison, now try the
                    * case sensitive comparison, which is required for proper
                    * collation.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len);
                   if (rc == -1)
                           break;
                   if (rc)
                           continue;
                   /*
                    * Perfect match, this will never happen as the
                    * ntfs_are_names_equal() call will have gotten a match but we
                    * still treat it correctly.
                    */
                   goto found_it2;
           }
           /*
            * We have finished with this index buffer without success. Check for
            * the presence of a child node.
            */
           if (ie->flags & INDEX_ENTRY_NODE) {
                   if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
                           ntfs_error(sb, "Index entry with child node found in "
                                           "a leaf node in directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           goto unm_err_out;
                   }
                   /* Child node present, descend into it. */
                   old_vcn = vcn;
                   vcn = sle64_to_cpup((sle64*)((u8*)ie +
                                   le16_to_cpu(ie->length) - 8));
                   if (vcn >= 0) {
                           /* If vcn is in the same page cache page as old_vcn we
                            * recycle the mapped page. */
                           if (old_vcn << vol->cluster_size_bits >>
                                           PAGE_CACHE_SHIFT == vcn <<
                                           vol->cluster_size_bits >>
                                           PAGE_CACHE_SHIFT)
                                   goto fast_descend_into_child_node;
                           unlock_page(page);
                           ntfs_unmap_page(page);
                           goto descend_into_child_node;
                   }
                   ntfs_error(sb, "Negative child node vcn in directory inode "
                                   "0x%lx.", dir_ni->mft_no);
                   goto unm_err_out;
           }
           /*
            * No child node present, return -ENOENT, unless we have got a matching
            * name cached in name in which case return the mft reference
            * associated with it.
            */
           if (name) {
                   unlock_page(page);
                   ntfs_unmap_page(page);
                   return name->mref;
           }
           ntfs_debug("Entry not found.");
           err = -ENOENT;
   unm_err_out:
           unlock_page(page);
           ntfs_unmap_page(page);
   err_out:
           if (!err)
                   err = -EIO;
           if (ctx)
                   ntfs_attr_put_search_ctx(ctx);
           if (m)
                   unmap_mft_record(dir_ni);
           if (name) {
                   kfree(name);
                   *res = NULL;
           }
           return ERR_MREF(err);
   dir_err_out:
           ntfs_error(sb, "Corrupt directory.  Aborting lookup.");
           goto err_out;
   }
   
   #if 0
   
   // TODO: (AIA)
   // The algorithm embedded in this code will be required for the time when we
   // want to support adding of entries to directories, where we require correct
   // collation of file names in order not to cause corruption of the filesystem.
   
   /**
    * ntfs_lookup_inode_by_name - find an inode in a directory given its name
    * @dir_ni:     ntfs inode of the directory in which to search for the name
    * @uname:      Unicode name for which to search in the directory
    * @uname_len:  length of the name @uname in Unicode characters
    *
    * Look for an inode with name @uname in the directory with inode @dir_ni.
    * ntfs_lookup_inode_by_name() walks the contents of the directory looking for
    * the Unicode name. If the name is found in the directory, the corresponding
    * inode number (>= 0) is returned as a mft reference in cpu format, i.e. it
    * is a 64-bit number containing the sequence number.
    *
    * On error, a negative value is returned corresponding to the error code. In
    * particular if the inode is not found -ENOENT is returned. Note that you
    * can't just check the return value for being negative, you have to check the
    * inode number for being negative which you can extract using MREC(return
    * value).
    *
    * Note, @uname_len does not include the (optional) terminating NULL character.
    */
   u64 ntfs_lookup_inode_by_name(ntfs_inode *dir_ni, const ntfschar *uname,
                   const int uname_len)
   {
           ntfs_volume *vol = dir_ni->vol;
           struct super_block *sb = vol->sb;
           MFT_RECORD *m;
           INDEX_ROOT *ir;
           INDEX_ENTRY *ie;
           INDEX_ALLOCATION *ia;
           u8 *index_end;
           u64 mref;
           ntfs_attr_search_ctx *ctx;
           int err, rc;
           IGNORE_CASE_BOOL ic;
           VCN vcn, old_vcn;
           struct address_space *ia_mapping;
           struct page *page;
           u8 *kaddr;
   
           /* Get hold of the mft record for the directory. */
           m = map_mft_record(dir_ni);
           if (IS_ERR(m)) {
                   ntfs_error(sb, "map_mft_record() failed with error code %ld.",
                                   -PTR_ERR(m));
                   return ERR_MREF(PTR_ERR(m));
           }
           ctx = ntfs_attr_get_search_ctx(dir_ni, m);
           if (!ctx) {
                   err = -ENOMEM;
                   goto err_out;
           }
           /* Find the index root attribute in the mft record. */
           err = ntfs_attr_lookup(AT_INDEX_ROOT, I30, 4, CASE_SENSITIVE, 0, NULL,
                           0, ctx);
           if (unlikely(err)) {
                   if (err == -ENOENT) {
                           ntfs_error(sb, "Index root attribute missing in "
                                           "directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           err = -EIO;
                   }
                   goto err_out;
           }
           /* Get to the index root value (it's been verified in read_inode). */
           ir = (INDEX_ROOT*)((u8*)ctx->attr +
                           le16_to_cpu(ctx->attr->data.resident.value_offset));
           index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
           /* The first index entry. */
           ie = (INDEX_ENTRY*)((u8*)&ir->index +
                           le32_to_cpu(ir->index.entries_offset));
           /*
            * Loop until we exceed valid memory (corruption case) or until we
            * reach the last entry.
            */
           for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                   /* Bounds checks. */
                   if ((u8*)ie < (u8*)ctx->mrec || (u8*)ie +
                                   sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                   (u8*)ie + le16_to_cpu(ie->key_length) >
                                   index_end)
                           goto dir_err_out;
                   /*
                    * The last entry cannot contain a name. It can however contain
                    * a pointer to a child node in the B+tree so we just break out.
                    */
                   if (ie->flags & INDEX_ENTRY_END)
                           break;
                   /*
                    * If the current entry has a name type of POSIX, the name is
                    * case sensitive and not otherwise. This has the effect of us
                    * not being able to access any POSIX file names which collate
                    * after the non-POSIX one when they only differ in case, but
                    * anyone doing screwy stuff like that deserves to burn in
                    * hell... Doing that kind of stuff on NT4 actually causes
                    * corruption on the partition even when using SP6a and Linux
                    * is not involved at all.
                    */
                   ic = ie->key.file_name.file_name_type ? IGNORE_CASE :
                                   CASE_SENSITIVE;
                   /*
                    * If the names match perfectly, we are done and return the
                    * mft reference of the inode (i.e. the inode number together
                    * with the sequence number for consistency checking. We
                    * convert it to cpu format before returning.
                    */
                   if (ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, ic,
                                   vol->upcase, vol->upcase_len)) {
   found_it:
                           mref = le64_to_cpu(ie->data.dir.indexed_file);
                           ntfs_attr_put_search_ctx(ctx);
                           unmap_mft_record(dir_ni);
                           return mref;
                   }
                   /*
                    * Not a perfect match, need to do full blown collation so we
                    * know which way in the B+tree we have to go.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len);
                   /*
                    * If uname collates before the name of the current entry, there
                    * is definitely no such name in this index but we might need to
                    * descend into the B+tree so we just break out of the loop.
                    */
                   if (rc == -1)
                           break;
                   /* The names are not equal, continue the search. */
                   if (rc)
                           continue;
                   /*
                    * Names match with case insensitive comparison, now try the
                    * case sensitive comparison, which is required for proper
                    * collation.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len);
                   if (rc == -1)
                           break;
                   if (rc)
                           continue;
                   /*
                    * Perfect match, this will never happen as the
                    * ntfs_are_names_equal() call will have gotten a match but we
                    * still treat it correctly.
                    */
                   goto found_it;
           }
           /*
            * We have finished with this index without success. Check for the
            * presence of a child node.
            */
           if (!(ie->flags & INDEX_ENTRY_NODE)) {
                   /* No child node, return -ENOENT. */
                   err = -ENOENT;
                   goto err_out;
           } /* Child node present, descend into it. */
           /* Consistency check: Verify that an index allocation exists. */
           if (!NInoIndexAllocPresent(dir_ni)) {
                   ntfs_error(sb, "No index allocation attribute but index entry "
                                   "requires one. Directory inode 0x%lx is "
                                   "corrupt or driver bug.", dir_ni->mft_no);
                   goto err_out;
           }
           /* Get the starting vcn of the index_block holding the child node. */
           vcn = sle64_to_cpup((u8*)ie + le16_to_cpu(ie->length) - 8);
           ia_mapping = VFS_I(dir_ni)->i_mapping;
           /*
            * We are done with the index root and the mft record. Release them,
            * otherwise we deadlock with ntfs_map_page().
            */
           ntfs_attr_put_search_ctx(ctx);
           unmap_mft_record(dir_ni);
           m = NULL;
           ctx = NULL;
   descend_into_child_node:
           /*
            * Convert vcn to index into the index allocation attribute in units
            * of PAGE_CACHE_SIZE and map the page cache page, reading it from
            * disk if necessary.
            */
           page = ntfs_map_page(ia_mapping, vcn <<
                           dir_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
           if (IS_ERR(page)) {
                   ntfs_error(sb, "Failed to map directory index page, error %ld.",
                                   -PTR_ERR(page));
                   err = PTR_ERR(page);
                   goto err_out;
           }
           lock_page(page);
           kaddr = (u8*)page_address(page);
   fast_descend_into_child_node:
           /* Get to the index allocation block. */
           ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
                           dir_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
           /* Bounds checks. */
           if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
                   ntfs_error(sb, "Out of bounds check failed. Corrupt directory "
                                   "inode 0x%lx or driver bug.", dir_ni->mft_no);
                   goto unm_err_out;
           }
           /* Catch multi sector transfer fixup errors. */
           if (unlikely(!ntfs_is_indx_record(ia->magic))) {
                   ntfs_error(sb, "Directory index record with vcn 0x%llx is "
                                   "corrupt.  Corrupt inode 0x%lx.  Run chkdsk.",
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
                   ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
                                   "different from expected VCN (0x%llx). "
                                   "Directory inode 0x%lx is corrupt or driver "
                                   "bug.", (unsigned long long)
                                   sle64_to_cpu(ia->index_block_vcn),
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
                           dir_ni->itype.index.block_size) {
                   ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                   "0x%lx has a size (%u) differing from the "
                                   "directory specified size (%u). Directory "
                                   "inode is corrupt or driver bug.",
                                   (unsigned long long)vcn, dir_ni->mft_no,
                                   le32_to_cpu(ia->index.allocated_size) + 0x18,
                                   dir_ni->itype.index.block_size);
                   goto unm_err_out;
           }
           index_end = (u8*)ia + dir_ni->itype.index.block_size;
           if (index_end > kaddr + PAGE_CACHE_SIZE) {
                   ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                   "0x%lx crosses page boundary. Impossible! "
                                   "Cannot access! This is probably a bug in the "
                                   "driver.", (unsigned long long)vcn,
                                   dir_ni->mft_no);
                   goto unm_err_out;
           }
           index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
           if (index_end > (u8*)ia + dir_ni->itype.index.block_size) {
                   ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of directory "
                                   "inode 0x%lx exceeds maximum size.",
                                   (unsigned long long)vcn, dir_ni->mft_no);
                   goto unm_err_out;
           }
           /* The first index entry. */
           ie = (INDEX_ENTRY*)((u8*)&ia->index +
                           le32_to_cpu(ia->index.entries_offset));
           /*
            * Iterate similar to above big loop but applied to index buffer, thus
            * loop until we exceed valid memory (corruption case) or until we
            * reach the last entry.
            */
           for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                   /* Bounds check. */
                   if ((u8*)ie < (u8*)ia || (u8*)ie +
                                   sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                   (u8*)ie + le16_to_cpu(ie->key_length) >
                                   index_end) {
                           ntfs_error(sb, "Index entry out of bounds in "
                                           "directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           goto unm_err_out;
                   }
                   /*
                    * The last entry cannot contain a name. It can however contain
                    * a pointer to a child node in the B+tree so we just break out.
                    */
                   if (ie->flags & INDEX_ENTRY_END)
                           break;
                   /*
                    * If the current entry has a name type of POSIX, the name is
                    * case sensitive and not otherwise. This has the effect of us
                    * not being able to access any POSIX file names which collate
                    * after the non-POSIX one when they only differ in case, but
                    * anyone doing screwy stuff like that deserves to burn in
                    * hell... Doing that kind of stuff on NT4 actually causes
                    * corruption on the partition even when using SP6a and Linux
                    * is not involved at all.
                    */
                   ic = ie->key.file_name.file_name_type ? IGNORE_CASE :
                                   CASE_SENSITIVE;
                   /*
                    * If the names match perfectly, we are done and return the
                    * mft reference of the inode (i.e. the inode number together
                    * with the sequence number for consistency checking. We
                    * convert it to cpu format before returning.
                    */
                   if (ntfs_are_names_equal(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, ic,
                                   vol->upcase, vol->upcase_len)) {
   found_it2:
                           mref = le64_to_cpu(ie->data.dir.indexed_file);
                           unlock_page(page);
                           ntfs_unmap_page(page);
                           return mref;
                   }
                   /*
                    * Not a perfect match, need to do full blown collation so we
                    * know which way in the B+tree we have to go.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   IGNORE_CASE, vol->upcase, vol->upcase_len);
                   /*
                    * If uname collates before the name of the current entry, there
                    * is definitely no such name in this index but we might need to
                    * descend into the B+tree so we just break out of the loop.
                    */
                   if (rc == -1)
                           break;
                   /* The names are not equal, continue the search. */
                   if (rc)
                           continue;
                   /*
                    * Names match with case insensitive comparison, now try the
                    * case sensitive comparison, which is required for proper
                    * collation.
                    */
                   rc = ntfs_collate_names(uname, uname_len,
                                   (ntfschar*)&ie->key.file_name.file_name,
                                   ie->key.file_name.file_name_length, 1,
                                   CASE_SENSITIVE, vol->upcase, vol->upcase_len);
                   if (rc == -1)
                           break;
                   if (rc)
                           continue;
                   /*
                    * Perfect match, this will never happen as the
                    * ntfs_are_names_equal() call will have gotten a match but we
                    * still treat it correctly.
                    */
                   goto found_it2;
           }
           /*
            * We have finished with this index buffer without success. Check for
            * the presence of a child node.
            */
           if (ie->flags & INDEX_ENTRY_NODE) {
                   if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
                           ntfs_error(sb, "Index entry with child node found in "
                                           "a leaf node in directory inode 0x%lx.",
                                           dir_ni->mft_no);
                           goto unm_err_out;
                   }
                   /* Child node present, descend into it. */
                   old_vcn = vcn;
                   vcn = sle64_to_cpup((u8*)ie + le16_to_cpu(ie->length) - 8);
                   if (vcn >= 0) {
                           /* If vcn is in the same page cache page as old_vcn we
                            * recycle the mapped page. */
                           if (old_vcn << vol->cluster_size_bits >>
                                           PAGE_CACHE_SHIFT == vcn <<
                                           vol->cluster_size_bits >>
                                           PAGE_CACHE_SHIFT)
                                   goto fast_descend_into_child_node;
                           unlock_page(page);
                           ntfs_unmap_page(page);
                           goto descend_into_child_node;
                   }
                   ntfs_error(sb, "Negative child node vcn in directory inode "
                                   "0x%lx.", dir_ni->mft_no);
                   goto unm_err_out;
           }
           /* No child node, return -ENOENT. */
           ntfs_debug("Entry not found.");
           err = -ENOENT;
   unm_err_out:
           unlock_page(page);
           ntfs_unmap_page(page);
   err_out:
           if (!err)
                   err = -EIO;
           if (ctx)
                   ntfs_attr_put_search_ctx(ctx);
           if (m)
                   unmap_mft_record(dir_ni);
           return ERR_MREF(err);
   dir_err_out:
           ntfs_error(sb, "Corrupt directory. Aborting lookup.");
           goto err_out;
  }
  
  #endif
  
  /**
   * ntfs_filldir - ntfs specific filldir method
   * @vol:        current ntfs volume
   * @fpos:       position in the directory
   * @ndir:       ntfs inode of current directory
   * @ia_page:    page in which the index allocation buffer @ie is in resides
   * @ie:         current index entry
   * @name:       buffer to use for the converted name
   * @dirent:     vfs filldir callback context
   * @filldir:    vfs filldir callback
   *
   * Convert the Unicode @name to the loaded NLS and pass it to the @filldir
   * callback.
   *
   * If @ia_page is not NULL it is the locked page containing the index
   * allocation block containing the index entry @ie.
   *
   * Note, we drop (and then reacquire) the page lock on @ia_page across the
   * @filldir() call otherwise we would deadlock with NFSd when it calls ->lookup
   * since ntfs_lookup() will lock the same page.  As an optimization, we do not
   * retake the lock if we are returning a non-zero value as ntfs_readdir()
   * would need to drop the lock immediately anyway.
   */
  static inline int ntfs_filldir(ntfs_volume *vol, loff_t fpos,
                  ntfs_inode *ndir, struct page *ia_page, INDEX_ENTRY *ie,
                  u8 *name, void *dirent, filldir_t filldir)
  {
          unsigned long mref;
          int name_len, rc;
          unsigned dt_type;
          FILE_NAME_TYPE_FLAGS name_type;
  
          name_type = ie->key.file_name.file_name_type;
          if (name_type == FILE_NAME_DOS) {
                  ntfs_debug("Skipping DOS name space entry.");
                  return 0;
          }
          if (MREF_LE(ie->data.dir.indexed_file) == FILE_root) {
                  ntfs_debug("Skipping root directory self reference entry.");
                  return 0;
          }
          if (MREF_LE(ie->data.dir.indexed_file) < FILE_first_user &&
                          !NVolShowSystemFiles(vol)) {
                  ntfs_debug("Skipping system file.");
                  return 0;
          }
          name_len = ntfs_ucstonls(vol, (ntfschar*)&ie->key.file_name.file_name,
                          ie->key.file_name.file_name_length, &name,
                          NTFS_MAX_NAME_LEN * NLS_MAX_CHARSET_SIZE + 1);
          if (name_len <= 0) {
                  ntfs_warning(vol->sb, "Skipping unrepresentable inode 0x%llx.",
                                  (long long)MREF_LE(ie->data.dir.indexed_file));
                  return 0;
          }
          if (ie->key.file_name.file_attributes &
                          FILE_ATTR_DUP_FILE_NAME_INDEX_PRESENT)
                  dt_type = DT_DIR;
          else
                  dt_type = DT_REG;
          mref = MREF_LE(ie->data.dir.indexed_file);
          /*
           * Drop the page lock otherwise we deadlock with NFS when it calls
           * ->lookup since ntfs_lookup() will lock the same page.
           */
          if (ia_page)
                  unlock_page(ia_page);
          ntfs_debug("Calling filldir for %s with len %i, fpos 0x%llx, inode "
                          "0x%lx, DT_%s.", name, name_len, fpos, mref,
                          dt_type == DT_DIR ? "DIR" : "REG");
          rc = filldir(dirent, name, name_len, fpos, mref, dt_type);
          /* Relock the page but not if we are aborting ->readdir. */
          if (!rc && ia_page)
                  lock_page(ia_page);
          return rc;
  }
  
  /*
   * We use the same basic approach as the old NTFS driver, i.e. we parse the
   * index root entries and then the index allocation entries that are marked
   * as in use in the index bitmap.
   *
   * While this will return the names in random order this doesn't matter for
   * ->readdir but OTOH results in a faster ->readdir.
   *
   * VFS calls ->readdir without BKL but with i_mutex held. This protects the VFS
   * parts (e.g. ->f_pos and ->i_size, and it also protects against directory
   * modifications).
   *
   * Locking:  - Caller must hold i_mutex on the directory.
   *           - Each page cache page in the index allocation mapping must be
   *             locked whilst being accessed otherwise we may find a corrupt
   *             page due to it being under ->writepage at the moment which
   *             applies the mst protection fixups before writing out and then
   *             removes them again after the write is complete after which it 
   *             unlocks the page.
   */
  static int ntfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
  {
          s64 ia_pos, ia_start, prev_ia_pos, bmp_pos;
          loff_t fpos, i_size;
          struct inode *bmp_vi, *vdir = filp->f_path.dentry->d_inode;
          struct super_block *sb = vdir->i_sb;
          ntfs_inode *ndir = NTFS_I(vdir);
          ntfs_volume *vol = NTFS_SB(sb);
          MFT_RECORD *m;
          INDEX_ROOT *ir = NULL;
          INDEX_ENTRY *ie;
          INDEX_ALLOCATION *ia;
          u8 *name = NULL;
          int rc, err, ir_pos, cur_bmp_pos;
          struct address_space *ia_mapping, *bmp_mapping;
          struct page *bmp_page = NULL, *ia_page = NULL;
          u8 *kaddr, *bmp, *index_end;
          ntfs_attr_search_ctx *ctx;
  
          fpos = filp->f_pos;
          ntfs_debug("Entering for inode 0x%lx, fpos 0x%llx.",
                          vdir->i_ino, fpos);
          rc = err = 0;
          /* Are we at end of dir yet? */
          i_size = i_size_read(vdir);
          if (fpos >= i_size + vol->mft_record_size)
                  goto done;
          /* Emulate . and .. for all directories. */
          if (!fpos) {
                  ntfs_debug("Calling filldir for . with len 1, fpos 0x0, "
                                  "inode 0x%lx, DT_DIR.", vdir->i_ino);
                  rc = filldir(dirent, ".", 1, fpos, vdir->i_ino, DT_DIR);
                  if (rc)
                          goto done;
                  fpos++;
          }
          if (fpos == 1) {
                  ntfs_debug("Calling filldir for .. with len 2, fpos 0x1, "
                                  "inode 0x%lx, DT_DIR.",
                                  (unsigned long)parent_ino(filp->f_path.dentry));
                  rc = filldir(dirent, "..", 2, fpos,
                                  parent_ino(filp->f_path.dentry), DT_DIR);
                  if (rc)
                          goto done;
                  fpos++;
          }
          m = NULL;
          ctx = NULL;
          /*
           * Allocate a buffer to store the current name being processed
           * converted to format determined by current NLS.
           */
          name = kmalloc(NTFS_MAX_NAME_LEN * NLS_MAX_CHARSET_SIZE + 1, GFP_NOFS);
          if (unlikely(!name)) {
                  err = -ENOMEM;
                  goto err_out;
          }
          /* Are we jumping straight into the index allocation attribute? */
          if (fpos >= vol->mft_record_size)
                  goto skip_index_root;
          /* Get hold of the mft record for the directory. */
          m = map_mft_record(ndir);
          if (IS_ERR(m)) {
                  err = PTR_ERR(m);
                  m = NULL;
                  goto err_out;
          }
          ctx = ntfs_attr_get_search_ctx(ndir, m);
          if (unlikely(!ctx)) {
                  err = -ENOMEM;
                  goto err_out;
          }
          /* Get the offset into the index root attribute. */
          ir_pos = (s64)fpos;
          /* Find the index root attribute in the mft record. */
          err = ntfs_attr_lookup(AT_INDEX_ROOT, I30, 4, CASE_SENSITIVE, 0, NULL,
                          0, ctx);
          if (unlikely(err)) {
                  ntfs_error(sb, "Index root attribute missing in directory "
                                  "inode 0x%lx.", vdir->i_ino);
                  goto err_out;
          }
          /*
           * Copy the index root attribute value to a buffer so that we can put
           * the search context and unmap the mft record before calling the
           * filldir() callback.  We need to do this because of NFSd which calls
           * ->lookup() from its filldir callback() and this causes NTFS to
           * deadlock as ntfs_lookup() maps the mft record of the directory and
           * we have got it mapped here already.  The only solution is for us to
           * unmap the mft record here so that a call to ntfs_lookup() is able to
           * map the mft record without deadlocking.
           */
          rc = le32_to_cpu(ctx->attr->data.resident.value_length);
          ir = kmalloc(rc, GFP_NOFS);
          if (unlikely(!ir)) {
                  err = -ENOMEM;
                  goto err_out;
          }
          /* Copy the index root value (it has been verified in read_inode). */
          memcpy(ir, (u8*)ctx->attr +
                          le16_to_cpu(ctx->attr->data.resident.value_offset), rc);
          ntfs_attr_put_search_ctx(ctx);
          unmap_mft_record(ndir);
          ctx = NULL;
          m = NULL;
          index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
          /* The first index entry. */
          ie = (INDEX_ENTRY*)((u8*)&ir->index +
                          le32_to_cpu(ir->index.entries_offset));
          /*
           * Loop until we exceed valid memory (corruption case) or until we
           * reach the last entry or until filldir tells us it has had enough
           * or signals an error (both covered by the rc test).
           */
          for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                  ntfs_debug("In index root, offset 0x%zx.", (u8*)ie - (u8*)ir);
                  /* Bounds checks. */
                  if (unlikely((u8*)ie < (u8*)ir || (u8*)ie +
                                  sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                  (u8*)ie + le16_to_cpu(ie->key_length) >
                                  index_end))
                          goto err_out;
                  /* The last entry cannot contain a name. */
                  if (ie->flags & INDEX_ENTRY_END)
                          break;
                  /* Skip index root entry if continuing previous readdir. */
                  if (ir_pos > (u8*)ie - (u8*)ir)
                          continue;
                  /* Advance the position even if going to skip the entry. */
                  fpos = (u8*)ie - (u8*)ir;
                  /* Submit the name to the filldir callback. */
                  rc = ntfs_filldir(vol, fpos, ndir, NULL, ie, name, dirent,
                                  filldir);
                  if (rc) {
                          kfree(ir);
                          goto abort;
                  }
          }
          /* We are done with the index root and can free the buffer. */
          kfree(ir);
          ir = NULL;
          /* If there is no index allocation attribute we are finished. */
          if (!NInoIndexAllocPresent(ndir))
                  goto EOD;
          /* Advance fpos to the beginning of the index allocation. */
          fpos = vol->mft_record_size;
  skip_index_root:
          kaddr = NULL;
          prev_ia_pos = -1LL;
          /* Get the offset into the index allocation attribute. */
          ia_pos = (s64)fpos - vol->mft_record_size;
          ia_mapping = vdir->i_mapping;
          ntfs_debug("Inode 0x%lx, getting index bitmap.", vdir->i_ino);
          bmp_vi = ntfs_attr_iget(vdir, AT_BITMAP, I30, 4);
          if (IS_ERR(bmp_vi)) {
                  ntfs_error(sb, "Failed to get bitmap attribute.");
                  err = PTR_ERR(bmp_vi);
                  goto err_out;
          }
          bmp_mapping = bmp_vi->i_mapping;
          /* Get the starting bitmap bit position and sanity check it. */
          bmp_pos = ia_pos >> ndir->itype.index.block_size_bits;
          if (unlikely(bmp_pos >> 3 >= i_size_read(bmp_vi))) {
                  ntfs_error(sb, "Current index allocation position exceeds "
                                  "index bitmap size.");
                  goto iput_err_out;
          }
          /* Get the starting bit position in the current bitmap page. */
          cur_bmp_pos = bmp_pos & ((PAGE_CACHE_SIZE * 8) - 1);
          bmp_pos &= ~(u64)((PAGE_CACHE_SIZE * 8) - 1);
  get_next_bmp_page:
          ntfs_debug("Reading bitmap with page index 0x%llx, bit ofs 0x%llx",
                          (unsigned long long)bmp_pos >> (3 + PAGE_CACHE_SHIFT),
                          (unsigned long long)bmp_pos &
                          (unsigned long long)((PAGE_CACHE_SIZE * 8) - 1));
          bmp_page = ntfs_map_page(bmp_mapping,
                          bmp_pos >> (3 + PAGE_CACHE_SHIFT));
          if (IS_ERR(bmp_page)) {
                  ntfs_error(sb, "Reading index bitmap failed.");
                  err = PTR_ERR(bmp_page);
                  bmp_page = NULL;
                  goto iput_err_out;
          }
          bmp = (u8*)page_address(bmp_page);
          /* Find next index block in use. */
          while (!(bmp[cur_bmp_pos >> 3] & (1 << (cur_bmp_pos & 7)))) {
  find_next_index_buffer:
                  cur_bmp_pos++;
                  /*
                   * If we have reached the end of the bitmap page, get the next
                   * page, and put away the old one.
                   */
                  if (unlikely((cur_bmp_pos >> 3) >= PAGE_CACHE_SIZE)) {
                          ntfs_unmap_page(bmp_page);
                          bmp_pos += PAGE_CACHE_SIZE * 8;
                          cur_bmp_pos = 0;
                          goto get_next_bmp_page;
                  }
                  /* If we have reached the end of the bitmap, we are done. */
                  if (unlikely(((bmp_pos + cur_bmp_pos) >> 3) >= i_size))
                          goto unm_EOD;
                  ia_pos = (bmp_pos + cur_bmp_pos) <<
                                  ndir->itype.index.block_size_bits;
          }
          ntfs_debug("Handling index buffer 0x%llx.",
                          (unsigned long long)bmp_pos + cur_bmp_pos);
          /* If the current index buffer is in the same page we reuse the page. */
          if ((prev_ia_pos & (s64)PAGE_CACHE_MASK) !=
                          (ia_pos & (s64)PAGE_CACHE_MASK)) {
                  prev_ia_pos = ia_pos;
                  if (likely(ia_page != NULL)) {
                          unlock_page(ia_page);
                          ntfs_unmap_page(ia_page);
                  }
                  /*
                   * Map the page cache page containing the current ia_pos,
                   * reading it from disk if necessary.
                   */
                  ia_page = ntfs_map_page(ia_mapping, ia_pos >> PAGE_CACHE_SHIFT);
                  if (IS_ERR(ia_page)) {
                          ntfs_error(sb, "Reading index allocation data failed.");
                          err = PTR_ERR(ia_page);
                          ia_page = NULL;
                          goto err_out;
                  }
                  lock_page(ia_page);
                  kaddr = (u8*)page_address(ia_page);
          }
          /* Get the current index buffer. */
          ia = (INDEX_ALLOCATION*)(kaddr + (ia_pos & ~PAGE_CACHE_MASK &
                          ~(s64)(ndir->itype.index.block_size - 1)));
          /* Bounds checks. */
          if (unlikely((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE)) {
                  ntfs_error(sb, "Out of bounds check failed. Corrupt directory "
                                  "inode 0x%lx or driver bug.", vdir->i_ino);
                  goto err_out;
          }
          /* Catch multi sector transfer fixup errors. */
          if (unlikely(!ntfs_is_indx_record(ia->magic))) {
                  ntfs_error(sb, "Directory index record with vcn 0x%llx is "
                                  "corrupt.  Corrupt inode 0x%lx.  Run chkdsk.",
                                  (unsigned long long)ia_pos >>
                                  ndir->itype.index.vcn_size_bits, vdir->i_ino);
                  goto err_out;
          }
          if (unlikely(sle64_to_cpu(ia->index_block_vcn) != (ia_pos &
                          ~(s64)(ndir->itype.index.block_size - 1)) >>
                          ndir->itype.index.vcn_size_bits)) {
                  ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
                                  "different from expected VCN (0x%llx). "
                                  "Directory inode 0x%lx is corrupt or driver "
                                  "bug. ", (unsigned long long)
                                  sle64_to_cpu(ia->index_block_vcn),
                                  (unsigned long long)ia_pos >>
                                  ndir->itype.index.vcn_size_bits, vdir->i_ino);
                  goto err_out;
          }
          if (unlikely(le32_to_cpu(ia->index.allocated_size) + 0x18 !=
                          ndir->itype.index.block_size)) {
                  ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                  "0x%lx has a size (%u) differing from the "
                                  "directory specified size (%u). Directory "
                                  "inode is corrupt or driver bug.",
                                  (unsigned long long)ia_pos >>
                                  ndir->itype.index.vcn_size_bits, vdir->i_ino,
                                  le32_to_cpu(ia->index.allocated_size) + 0x18,
                                  ndir->itype.index.block_size);
                  goto err_out;
          }
          index_end = (u8*)ia + ndir->itype.index.block_size;
          if (unlikely(index_end > kaddr + PAGE_CACHE_SIZE)) {
                  ntfs_error(sb, "Index buffer (VCN 0x%llx) of directory inode "
                                  "0x%lx crosses page boundary. Impossible! "
                                  "Cannot access! This is probably a bug in the "
                                  "driver.", (unsigned long long)ia_pos >>
                                  ndir->itype.index.vcn_size_bits, vdir->i_ino);
                  goto err_out;
          }
          ia_start = ia_pos & ~(s64)(ndir->itype.index.block_size - 1);
          index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
          if (unlikely(index_end > (u8*)ia + ndir->itype.index.block_size)) {
                  ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of directory "
                                  "inode 0x%lx exceeds maximum size.",
                                  (unsigned long long)ia_pos >>
                                  ndir->itype.index.vcn_size_bits, vdir->i_ino);
                  goto err_out;
          }
          /* The first index entry in this index buffer. */
          ie = (INDEX_ENTRY*)((u8*)&ia->index +
                          le32_to_cpu(ia->index.entries_offset));
          /*
           * Loop until we exceed valid memory (corruption case) or until we
           * reach the last entry or until filldir tells us it has had enough
           * or signals an error (both covered by the rc test).
           */
          for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
                  ntfs_debug("In index allocation, offset 0x%llx.",
                                  (unsigned long long)ia_start +
                                  (unsigned long long)((u8*)ie - (u8*)ia));
                  /* Bounds checks. */
                  if (unlikely((u8*)ie < (u8*)ia || (u8*)ie +
                                  sizeof(INDEX_ENTRY_HEADER) > index_end ||
                                  (u8*)ie + le16_to_cpu(ie->key_length) >
                                  index_end))
                          goto err_out;
                  /* The last entry cannot contain a name. */
                  if (ie->flags & INDEX_ENTRY_END)
                          break;
                  /* Skip index block entry if continuing previous readdir. */
                  if (ia_pos - ia_start > (u8*)ie - (u8*)ia)
                          continue;
                  /* Advance the position even if going to skip the entry. */
                  fpos = (u8*)ie - (u8*)ia +
                                  (sle64_to_cpu(ia->index_block_vcn) <<
                                  ndir->itype.index.vcn_size_bits) +
                                  vol->mft_record_size;
                  /*
                   * Submit the name to the @filldir callback.  Note,
                   * ntfs_filldir() drops the lock on @ia_page but it retakes it
                   * before returning, unless a non-zero value is returned in
                   * which case the page is left unlocked.
                   */
                  rc = ntfs_filldir(vol, fpos, ndir, ia_page, ie, name, dirent,
                                  filldir);
                  if (rc) {
                          /* @ia_page is already unlocked in this case. */
                          ntfs_unmap_page(ia_page);
                          ntfs_unmap_page(bmp_page);
                          iput(bmp_vi);
                          goto abort;
                  }
          }
          goto find_next_index_buffer;
  unm_EOD:
          if (ia_page) {
                  unlock_page(ia_page);
                  ntfs_unmap_page(ia_page);
          }
          ntfs_unmap_page(bmp_page);
          iput(bmp_vi);
  EOD:
          /* We are finished, set fpos to EOD. */
          fpos = i_size + vol->mft_record_size;
  abort:
          kfree(name);
  done:
  #ifdef DEBUG
          if (!rc)
                  ntfs_debug("EOD, fpos 0x%llx, returning 0.", fpos);
          else
                  ntfs_debug("filldir returned %i, fpos 0x%llx, returning 0.",
                                  rc, fpos);
  #endif
          filp->f_pos = fpos;
          return 0;
  err_out:
          if (bmp_page) {
                  ntfs_unmap_page(bmp_page);
  iput_err_out:
                  iput(bmp_vi);
          }
          if (ia_page) {
                  unlock_page(ia_page);
                  ntfs_unmap_page(ia_page);
          }
          kfree(ir);
          kfree(name);
          if (ctx)
                  ntfs_attr_put_search_ctx(ctx);
          if (m)
                  unmap_mft_record(ndir);
          if (!err)
                  err = -EIO;
          ntfs_debug("Failed. Returning error code %i.", -err);
          filp->f_pos = fpos;
          return err;
  }
  
  /**
   * ntfs_dir_open - called when an inode is about to be opened
   * @vi:         inode to be opened
   * @filp:       file structure describing the inode
   *
   * Limit directory size to the page cache limit on architectures where unsigned
   * long is 32-bits. This is the most we can do for now without overflowing the
   * page cache page index. Doing it this way means we don't run into problems
   * because of existing too large directories. It would be better to allow the
   * user to read the accessible part of the directory but I doubt very much
   * anyone is going to hit this check on a 32-bit architecture, so there is no
   * point in adding the extra complexity required to support this.
   *
   * On 64-bit architectures, the check is hopefully optimized away by the
   * compiler.
   */
  static int ntfs_dir_open(struct inode *vi, struct file *filp)
  {
          if (sizeof(unsigned long) < 8) {
                  if (i_size_read(vi) > MAX_LFS_FILESIZE)
                          return -EFBIG;
          }
          return 0;
  }
  
  #ifdef NTFS_RW
  
  /**
   * ntfs_dir_fsync - sync a directory to disk
   * @filp:       directory to be synced
   * @dentry:     dentry describing the directory to sync
   * @datasync:   if non-zero only flush user data and not metadata
   *
   * Data integrity sync of a directory to disk.  Used for fsync, fdatasync, and
   * msync system calls.  This function is based on file.c::ntfs_file_fsync().
   *
   * Write the mft record and all associated extent mft records as well as the
   * $INDEX_ALLOCATION and $BITMAP attributes and then sync the block device.
   *
   * If @datasync is true, we do not wait on the inode(s) to be written out
   * but we always wait on the page cache pages to be written out.
   *
   * Note: In the past @filp could be NULL so we ignore it as we don't need it
   * anyway.
   *
   * Locking: Caller must hold i_mutex on the inode.
   *
   * TODO: We should probably also write all attribute/index inodes associated
   * with this inode but since we have no simple way of getting to them we ignore
   * this problem for now.  We do write the $BITMAP attribute if it is present
   * which is the important one for a directory so things are not too bad.
   */
  static int ntfs_dir_fsync(struct file *filp, loff_t start, loff_t end,
                            int datasync)
  {
          struct inode *bmp_vi, *vi = filp->f_mapping->host;
          int err, ret;
          ntfs_attr na;
  
          ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
  
          err = filemap_write_and_wait_range(vi->i_mapping, start, end);
          if (err)
                  return err;
          mutex_lock(&vi->i_mutex);
  
          BUG_ON(!S_ISDIR(vi->i_mode));
          /* If the bitmap attribute inode is in memory sync it, too. */
          na.mft_no = vi->i_ino;
          na.type = AT_BITMAP;
          na.name = I30;
          na.name_len = 4;
          bmp_vi = ilookup5(vi->i_sb, vi->i_ino, (test_t)ntfs_test_inode, &na);
          if (bmp_vi) {
                  write_inode_now(bmp_vi, !datasync);
                  iput(bmp_vi);
          }
          ret = __ntfs_write_inode(vi, 1);
          write_inode_now(vi, !datasync);
          err = sync_blockdev(vi->i_sb->s_bdev);
          if (unlikely(err && !ret))
                  ret = err;
          if (likely(!ret))
                  ntfs_debug("Done.");
          else
                  ntfs_warning(vi->i_sb, "Failed to f%ssync inode 0x%lx.  Error "
                                  "%u.", datasync ? "data" : "", vi->i_ino, -ret);
          mutex_unlock(&vi->i_mutex);
          return ret;
  }
  
  #endif /* NTFS_RW */
  
  const struct file_operations ntfs_dir_ops = {
          .llseek         = generic_file_llseek,  /* Seek inside directory. */
          .read           = generic_read_dir,     /* Return -EISDIR. */
          .readdir        = ntfs_readdir,         /* Read directory contents. */
  #ifdef NTFS_RW
          .fsync          = ntfs_dir_fsync,       /* Sync a directory to disk. */
          /*.aio_fsync    = ,*/                   /* Sync all outstanding async
                                                     i/o operations on a kiocb. */
  #endif /* NTFS_RW */
          /*.ioctl        = ,*/                   /* Perform function on the
                                                     mounted filesystem. */
          .open           = ntfs_dir_open,        /* Open directory. */
  };

Cache object: c9783bd390588fe9b4d3dcaeb11d27ab