OSCL-LXR linux-6.0.1/​fs/​ntfs/​dir.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 /**
  * dir.c - NTFS kernel directory operations. Part of the Linux-NTFS project.
  *
  * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  */
 
 #include <linux/buffer_head.h>
 #include <linux/slab.h>
 #include <linux/blkdev.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'), 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_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_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_MASK));
     /* Bounds checks. */
     if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_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_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_SHIFT == vcn <<
                     vol->cluster_size_bits >>
                     PAGE_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_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_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_MASK));
     /* Bounds checks. */
     if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_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_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_SHIFT == vcn <<
                     vol->cluster_size_bits >>
                     PAGE_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
  * @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
  * @actor:  what to feed the entries to
  *
  * 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,
         ntfs_inode *ndir, struct page *ia_page, INDEX_ENTRY *ie,
         u8 *name, struct dir_context *actor)
 {
     unsigned long mref;
     int name_len;
     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, actor->pos, mref,
             dt_type == DT_DIR ? "DIR" : "REG");
     if (!dir_emit(actor, name, name_len, mref, dt_type))
         return 1;
     /* Relock the page but not if we are aborting ->readdir. */
     if (ia_page)
         lock_page(ia_page);
     return 0;
 }
 
 /*
  * 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 *file, struct dir_context *actor)
 {
     s64 ia_pos, ia_start, prev_ia_pos, bmp_pos;
     loff_t i_size;
     struct inode *bmp_vi, *vdir = file_inode(file);
     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;
 
     ntfs_debug("Entering for inode 0x%lx, fpos 0x%llx.",
             vdir->i_ino, actor->pos);
     rc = err = 0;
     /* Are we at end of dir yet? */
     i_size = i_size_read(vdir);
     if (actor->pos >= i_size + vol->mft_record_size)
         return 0;
     /* Emulate . and .. for all directories. */
     if (!dir_emit_dots(file, actor))
         return 0;
     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 (actor->pos >= 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)actor->pos;
     /* 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. */
         actor->pos = (u8*)ie - (u8*)ir;
         /* Submit the name to the filldir callback. */
         rc = ntfs_filldir(vol, ndir, NULL, ie, name, actor);
         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. */
     actor->pos = vol->mft_record_size;
 skip_index_root:
     kaddr = NULL;
     prev_ia_pos = -1LL;
     /* Get the offset into the index allocation attribute. */
     ia_pos = (s64)actor->pos - 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_SIZE * 8) - 1);
     bmp_pos &= ~(u64)((PAGE_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_SHIFT),
             (unsigned long long)bmp_pos &
             (unsigned long long)((PAGE_SIZE * 8) - 1));
     bmp_page = ntfs_map_page(bmp_mapping,
             bmp_pos >> (3 + PAGE_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_SIZE)) {
             ntfs_unmap_page(bmp_page);
             bmp_pos += PAGE_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_MASK) !=
             (ia_pos & (s64)PAGE_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_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_MASK &
                       ~(s64)(ndir->itype.index.block_size - 1)));
     /* Bounds checks. */
     if (unlikely((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_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_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. */
         actor->pos = (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, ndir, ia_page, ie, name, actor);
         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. */
     actor->pos = i_size + vol->mft_record_size;
 abort:
     kfree(name);
     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);
     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 = file_write_and_wait_range(filp, start, end);
     if (err)
         return err;
     inode_lock(vi);
 
     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, 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);
     inode_unlock(vi);
     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. */
     .iterate    = ntfs_readdir,     /* Read directory contents. */
 #ifdef NTFS_RW
     .fsync      = ntfs_dir_fsync,   /* Sync a directory to disk. */
 #endif /* NTFS_RW */
     /*.ioctl    = ,*/           /* Perform function on the
                            mounted filesystem. */
     .open       = ntfs_dir_open,    /* Open directory. */
 };

This page was automatically generated by the 2.1.0 LXR engine. The LXR team