diff --git a/fs/hfs/mdb.c b/fs/hfs/mdb.c
new file mode 100644
index 0000000..4efb640
--- /dev/null
+++ b/fs/hfs/mdb.c
@@ -0,0 +1,343 @@
+/*
+ *  linux/fs/hfs/mdb.c
+ *
+ * Copyright (C) 1995-1997  Paul H. Hargrove
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ * This file may be distributed under the terms of the GNU General Public License.
+ *
+ * This file contains functions for reading/writing the MDB.
+ */
+
+#include <linux/cdrom.h>
+#include <linux/genhd.h>
+
+#include "hfs_fs.h"
+#include "btree.h"
+
+/*================ File-local data types ================*/
+
+/*
+ * The HFS Master Directory Block (MDB).
+ *
+ * Also known as the Volume Information Block (VIB), this structure is
+ * the HFS equivalent of a superblock.
+ *
+ * Reference: _Inside Macintosh: Files_ pages 2-59 through 2-62
+ *
+ * modified for HFS Extended
+ */
+
+static int hfs_get_last_session(struct super_block *sb,
+				sector_t *start, sector_t *size)
+{
+	struct cdrom_multisession ms_info;
+	struct cdrom_tocentry te;
+	int res;
+
+	/* default values */
+	*start = 0;
+	*size = sb->s_bdev->bd_inode->i_size >> 9;
+
+	if (HFS_SB(sb)->session >= 0) {
+		te.cdte_track = HFS_SB(sb)->session;
+		te.cdte_format = CDROM_LBA;
+		res = ioctl_by_bdev(sb->s_bdev, CDROMREADTOCENTRY, (unsigned long)&te);
+		if (!res && (te.cdte_ctrl & CDROM_DATA_TRACK) == 4) {
+			*start = (sector_t)te.cdte_addr.lba << 2;
+			return 0;
+		}
+		printk(KERN_ERR "HFS: Invalid session number or type of track\n");
+		return -EINVAL;
+	}
+	ms_info.addr_format = CDROM_LBA;
+	res = ioctl_by_bdev(sb->s_bdev, CDROMMULTISESSION, (unsigned long)&ms_info);
+	if (!res && ms_info.xa_flag)
+		*start = (sector_t)ms_info.addr.lba << 2;
+	return 0;
+}
+
+/*
+ * hfs_mdb_get()
+ *
+ * Build the in-core MDB for a filesystem, including
+ * the B-trees and the volume bitmap.
+ */
+int hfs_mdb_get(struct super_block *sb)
+{
+	struct buffer_head *bh;
+	struct hfs_mdb *mdb, *mdb2;
+	unsigned int block;
+	char *ptr;
+	int off2, len, size, sect;
+	sector_t part_start, part_size;
+	loff_t off;
+	__be16 attrib;
+
+	/* set the device driver to 512-byte blocks */
+	size = sb_min_blocksize(sb, HFS_SECTOR_SIZE);
+	if (!size)
+		return -EINVAL;
+
+	if (hfs_get_last_session(sb, &part_start, &part_size))
+		return -EINVAL;
+	while (1) {
+		/* See if this is an HFS filesystem */
+		bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb);
+		if (!bh)
+			goto out;
+
+		if (mdb->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC))
+			break;
+		brelse(bh);
+
+		/* check for a partition block
+		 * (should do this only for cdrom/loop though)
+		 */
+		if (hfs_part_find(sb, &part_start, &part_size))
+			goto out;
+	}
+
+	HFS_SB(sb)->alloc_blksz = size = be32_to_cpu(mdb->drAlBlkSiz);
+	if (!size || (size & (HFS_SECTOR_SIZE - 1))) {
+		hfs_warn("hfs_fs: bad allocation block size %d\n", size);
+		goto out_bh;
+	}
+
+	size = min(HFS_SB(sb)->alloc_blksz, (u32)PAGE_SIZE);
+	/* size must be a multiple of 512 */
+	while (size & (size - 1))
+		size -= HFS_SECTOR_SIZE;
+	sect = be16_to_cpu(mdb->drAlBlSt) + part_start;
+	/* align block size to first sector */
+	while (sect & ((size - 1) >> HFS_SECTOR_SIZE_BITS))
+		size >>= 1;
+	/* align block size to weird alloc size */
+	while (HFS_SB(sb)->alloc_blksz & (size - 1))
+		size >>= 1;
+	brelse(bh);
+	if (!sb_set_blocksize(sb, size)) {
+		printk("hfs_fs: unable to set blocksize to %u\n", size);
+		goto out;
+	}
+
+	bh = sb_bread512(sb, part_start + HFS_MDB_BLK, mdb);
+	if (!bh)
+		goto out;
+	if (mdb->drSigWord != cpu_to_be16(HFS_SUPER_MAGIC))
+		goto out_bh;
+
+	HFS_SB(sb)->mdb_bh = bh;
+	HFS_SB(sb)->mdb = mdb;
+
+	/* These parameters are read from the MDB, and never written */
+	HFS_SB(sb)->part_start = part_start;
+	HFS_SB(sb)->fs_ablocks = be16_to_cpu(mdb->drNmAlBlks);
+	HFS_SB(sb)->fs_div = HFS_SB(sb)->alloc_blksz >> sb->s_blocksize_bits;
+	HFS_SB(sb)->clumpablks = be32_to_cpu(mdb->drClpSiz) /
+				 HFS_SB(sb)->alloc_blksz;
+	if (!HFS_SB(sb)->clumpablks)
+		HFS_SB(sb)->clumpablks = 1;
+	HFS_SB(sb)->fs_start = (be16_to_cpu(mdb->drAlBlSt) + part_start) >>
+			       (sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS);
+
+	/* These parameters are read from and written to the MDB */
+	HFS_SB(sb)->free_ablocks = be16_to_cpu(mdb->drFreeBks);
+	HFS_SB(sb)->next_id = be32_to_cpu(mdb->drNxtCNID);
+	HFS_SB(sb)->root_files = be16_to_cpu(mdb->drNmFls);
+	HFS_SB(sb)->root_dirs = be16_to_cpu(mdb->drNmRtDirs);
+	HFS_SB(sb)->file_count = be32_to_cpu(mdb->drFilCnt);
+	HFS_SB(sb)->folder_count = be32_to_cpu(mdb->drDirCnt);
+
+	/* TRY to get the alternate (backup) MDB. */
+	sect = part_start + part_size - 2;
+	bh = sb_bread512(sb, sect, mdb2);
+	if (bh) {
+		if (mdb2->drSigWord == cpu_to_be16(HFS_SUPER_MAGIC)) {
+			HFS_SB(sb)->alt_mdb_bh = bh;
+			HFS_SB(sb)->alt_mdb = mdb2;
+		} else
+			brelse(bh);
+	}
+
+	if (!HFS_SB(sb)->alt_mdb) {
+		hfs_warn("hfs_fs: unable to locate alternate MDB\n");
+		hfs_warn("hfs_fs: continuing without an alternate MDB\n");
+	}
+
+	HFS_SB(sb)->bitmap = (__be32 *)__get_free_pages(GFP_KERNEL, PAGE_SIZE < 8192 ? 1 : 0);
+	if (!HFS_SB(sb)->bitmap)
+		goto out;
+
+	/* read in the bitmap */
+	block = be16_to_cpu(mdb->drVBMSt) + part_start;
+	off = (loff_t)block << HFS_SECTOR_SIZE_BITS;
+	size = (HFS_SB(sb)->fs_ablocks + 8) / 8;
+	ptr = (u8 *)HFS_SB(sb)->bitmap;
+	while (size) {
+		bh = sb_bread(sb, off >> sb->s_blocksize_bits);
+		if (!bh) {
+			hfs_warn("hfs_fs: unable to read volume bitmap\n");
+			goto out;
+		}
+		off2 = off & (sb->s_blocksize - 1);
+		len = min((int)sb->s_blocksize - off2, size);
+		memcpy(ptr, bh->b_data + off2, len);
+		brelse(bh);
+		ptr += len;
+		off += len;
+		size -= len;
+	}
+
+	HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp);
+	if (!HFS_SB(sb)->ext_tree) {
+		hfs_warn("hfs_fs: unable to open extent tree\n");
+		goto out;
+	}
+	HFS_SB(sb)->cat_tree = hfs_btree_open(sb, HFS_CAT_CNID, hfs_cat_keycmp);
+	if (!HFS_SB(sb)->cat_tree) {
+		hfs_warn("hfs_fs: unable to open catalog tree\n");
+		goto out;
+	}
+
+	attrib = mdb->drAtrb;
+	if (!(attrib & cpu_to_be16(HFS_SB_ATTRIB_UNMNT))) {
+		hfs_warn("HFS-fs warning: Filesystem was not cleanly unmounted, "
+			 "running fsck.hfs is recommended.  mounting read-only.\n");
+		sb->s_flags |= MS_RDONLY;
+	}
+	if ((attrib & cpu_to_be16(HFS_SB_ATTRIB_SLOCK))) {
+		hfs_warn("HFS-fs: Filesystem is marked locked, mounting read-only.\n");
+		sb->s_flags |= MS_RDONLY;
+	}
+	if (!(sb->s_flags & MS_RDONLY)) {
+		/* Mark the volume uncleanly unmounted in case we crash */
+		attrib &= cpu_to_be16(~HFS_SB_ATTRIB_UNMNT);
+		attrib |= cpu_to_be16(HFS_SB_ATTRIB_INCNSTNT);
+		mdb->drAtrb = attrib;
+		mdb->drWrCnt = cpu_to_be32(be32_to_cpu(mdb->drWrCnt) + 1);
+		mdb->drLsMod = hfs_mtime();
+
+		mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
+		hfs_buffer_sync(HFS_SB(sb)->mdb_bh);
+	}
+
+	return 0;
+
+out_bh:
+	brelse(bh);
+out:
+	hfs_mdb_put(sb);
+	return -EIO;
+}
+
+/*
+ * hfs_mdb_commit()
+ *
+ * Description:
+ *   This updates the MDB on disk (look also at hfs_write_super()).
+ *   It does not check, if the superblock has been modified, or
+ *   if the filesystem has been mounted read-only. It is mainly
+ *   called by hfs_write_super() and hfs_btree_extend().
+ * Input Variable(s):
+ *   struct hfs_mdb *mdb: Pointer to the hfs MDB
+ *   int backup;
+ * Output Variable(s):
+ *   NONE
+ * Returns:
+ *   void
+ * Preconditions:
+ *   'mdb' points to a "valid" (struct hfs_mdb).
+ * Postconditions:
+ *   The HFS MDB and on disk will be updated, by copying the possibly
+ *   modified fields from the in memory MDB (in native byte order) to
+ *   the disk block buffer.
+ *   If 'backup' is non-zero then the alternate MDB is also written
+ *   and the function doesn't return until it is actually on disk.
+ */
+void hfs_mdb_commit(struct super_block *sb)
+{
+	struct hfs_mdb *mdb = HFS_SB(sb)->mdb;
+
+	if (test_and_clear_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags)) {
+		/* These parameters may have been modified, so write them back */
+		mdb->drLsMod = hfs_mtime();
+		mdb->drFreeBks = cpu_to_be16(HFS_SB(sb)->free_ablocks);
+		mdb->drNxtCNID = cpu_to_be32(HFS_SB(sb)->next_id);
+		mdb->drNmFls = cpu_to_be16(HFS_SB(sb)->root_files);
+		mdb->drNmRtDirs = cpu_to_be16(HFS_SB(sb)->root_dirs);
+		mdb->drFilCnt = cpu_to_be32(HFS_SB(sb)->file_count);
+		mdb->drDirCnt = cpu_to_be32(HFS_SB(sb)->folder_count);
+
+		/* write MDB to disk */
+		mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
+	}
+
+	/* write the backup MDB, not returning until it is written.
+	 * we only do this when either the catalog or extents overflow
+	 * files grow. */
+	if (test_and_clear_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags) &&
+	    HFS_SB(sb)->alt_mdb) {
+		hfs_inode_write_fork(HFS_SB(sb)->ext_tree->inode, mdb->drXTExtRec,
+				     &mdb->drXTFlSize, NULL);
+		hfs_inode_write_fork(HFS_SB(sb)->cat_tree->inode, mdb->drCTExtRec,
+				     &mdb->drCTFlSize, NULL);
+		memcpy(HFS_SB(sb)->alt_mdb, HFS_SB(sb)->mdb, HFS_SECTOR_SIZE);
+		HFS_SB(sb)->alt_mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT);
+		HFS_SB(sb)->alt_mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT);
+		mark_buffer_dirty(HFS_SB(sb)->alt_mdb_bh);
+		hfs_buffer_sync(HFS_SB(sb)->alt_mdb_bh);
+	}
+
+	if (test_and_clear_bit(HFS_FLG_BITMAP_DIRTY, &HFS_SB(sb)->flags)) {
+		struct buffer_head *bh;
+		sector_t block;
+		char *ptr;
+		int off, size, len;
+
+		block = be16_to_cpu(HFS_SB(sb)->mdb->drVBMSt) + HFS_SB(sb)->part_start;
+		off = (block << HFS_SECTOR_SIZE_BITS) & (sb->s_blocksize - 1);
+		block >>= sb->s_blocksize_bits - HFS_SECTOR_SIZE_BITS;
+		size = (HFS_SB(sb)->fs_ablocks + 7) / 8;
+		ptr = (u8 *)HFS_SB(sb)->bitmap;
+		while (size) {
+			bh = sb_bread(sb, block);
+			if (!bh) {
+				hfs_warn("hfs_fs: unable to read volume bitmap\n");
+				break;
+			}
+			len = min((int)sb->s_blocksize - off, size);
+			memcpy(bh->b_data + off, ptr, len);
+			mark_buffer_dirty(bh);
+			brelse(bh);
+			block++;
+			off = 0;
+			ptr += len;
+			size -= len;
+		}
+	}
+}
+
+void hfs_mdb_close(struct super_block *sb)
+{
+	/* update volume attributes */
+	if (sb->s_flags & MS_RDONLY)
+		return;
+	HFS_SB(sb)->mdb->drAtrb |= cpu_to_be16(HFS_SB_ATTRIB_UNMNT);
+	HFS_SB(sb)->mdb->drAtrb &= cpu_to_be16(~HFS_SB_ATTRIB_INCNSTNT);
+	mark_buffer_dirty(HFS_SB(sb)->mdb_bh);
+}
+
+/*
+ * hfs_mdb_put()
+ *
+ * Release the resources associated with the in-core MDB.  */
+void hfs_mdb_put(struct super_block *sb)
+{
+	/* free the B-trees */
+	hfs_btree_close(HFS_SB(sb)->ext_tree);
+	hfs_btree_close(HFS_SB(sb)->cat_tree);
+
+	/* free the buffers holding the primary and alternate MDBs */
+	brelse(HFS_SB(sb)->mdb_bh);
+	brelse(HFS_SB(sb)->alt_mdb_bh);
+}