Initial import

1 files changed, 2917 insertions, 0 deletions

diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
new file mode 100644
index 000000000..3014a36a2
--- /dev/null
+++ b/fs/ntfs/mft.c
@@ -0,0 +1,2917 @@
+/**
+ * mft.c - NTFS kernel mft record operations. Part of the Linux-NTFS project.
+ *
+ * Copyright (c) 2001-2012 Anton Altaparmakov and Tuxera Inc.
+ * 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 <linux/swap.h>
+
+#include "attrib.h"
+#include "aops.h"
+#include "bitmap.h"
+#include "debug.h"
+#include "dir.h"
+#include "lcnalloc.h"
+#include "malloc.h"
+#include "mft.h"
+#include "ntfs.h"
+
+/**
+ * map_mft_record_page - map the page in which a specific mft record resides
+ * @ni:		ntfs inode whose mft record page to map
+ *
+ * This maps the page in which the mft record of the ntfs inode @ni is situated
+ * and returns a pointer to the mft record within the mapped page.
+ *
+ * Return value needs to be checked with IS_ERR() and if that is true PTR_ERR()
+ * contains the negative error code returned.
+ */
+static inline MFT_RECORD *map_mft_record_page(ntfs_inode *ni)
+{
+	loff_t i_size;
+	ntfs_volume *vol = ni->vol;
+	struct inode *mft_vi = vol->mft_ino;
+	struct page *page;
+	unsigned long index, end_index;
+	unsigned ofs;
+
+	BUG_ON(ni->page);
+	/*
+	 * The index into the page cache and the offset within the page cache
+	 * page of the wanted mft record. FIXME: We need to check for
+	 * overflowing the unsigned long, but I don't think we would ever get
+	 * here if the volume was that big...
+	 */
+	index = (u64)ni->mft_no << vol->mft_record_size_bits >>
+			PAGE_CACHE_SHIFT;
+	ofs = (ni->mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
+
+	i_size = i_size_read(mft_vi);
+	/* The maximum valid index into the page cache for $MFT's data. */
+	end_index = i_size >> PAGE_CACHE_SHIFT;
+
+	/* If the wanted index is out of bounds the mft record doesn't exist. */
+	if (unlikely(index >= end_index)) {
+		if (index > end_index || (i_size & ~PAGE_CACHE_MASK) < ofs +
+				vol->mft_record_size) {
+			page = ERR_PTR(-ENOENT);
+			ntfs_error(vol->sb, "Attempt to read mft record 0x%lx, "
+					"which is beyond the end of the mft.  "
+					"This is probably a bug in the ntfs "
+					"driver.", ni->mft_no);
+			goto err_out;
+		}
+	}
+	/* Read, map, and pin the page. */
+	page = ntfs_map_page(mft_vi->i_mapping, index);
+	if (likely(!IS_ERR(page))) {
+		/* Catch multi sector transfer fixup errors. */
+		if (likely(ntfs_is_mft_recordp((le32*)(page_address(page) +
+				ofs)))) {
+			ni->page = page;
+			ni->page_ofs = ofs;
+			return page_address(page) + ofs;
+		}
+		ntfs_error(vol->sb, "Mft record 0x%lx is corrupt.  "
+				"Run chkdsk.", ni->mft_no);
+		ntfs_unmap_page(page);
+		page = ERR_PTR(-EIO);
+		NVolSetErrors(vol);
+	}
+err_out:
+	ni->page = NULL;
+	ni->page_ofs = 0;
+	return (void*)page;
+}
+
+/**
+ * map_mft_record - map, pin and lock an mft record
+ * @ni:		ntfs inode whose MFT record to map
+ *
+ * First, take the mrec_lock mutex.  We might now be sleeping, while waiting
+ * for the mutex if it was already locked by someone else.
+ *
+ * The page of the record is mapped using map_mft_record_page() before being
+ * returned to the caller.
+ *
+ * This in turn uses ntfs_map_page() to get the page containing the wanted mft
+ * record (it in turn calls read_cache_page() which reads it in from disk if
+ * necessary, increments the use count on the page so that it cannot disappear
+ * under us and returns a reference to the page cache page).
+ *
+ * If read_cache_page() invokes ntfs_readpage() to load the page from disk, it
+ * sets PG_locked and clears PG_uptodate on the page. Once I/O has completed
+ * and the post-read mst fixups on each mft record in the page have been
+ * performed, the page gets PG_uptodate set and PG_locked cleared (this is done
+ * in our asynchronous I/O completion handler end_buffer_read_mft_async()).
+ * ntfs_map_page() waits for PG_locked to become clear and checks if
+ * PG_uptodate is set and returns an error code if not. This provides
+ * sufficient protection against races when reading/using the page.
+ *
+ * However there is the write mapping to think about. Doing the above described
+ * checking here will be fine, because when initiating the write we will set
+ * PG_locked and clear PG_uptodate making sure nobody is touching the page
+ * contents. Doing the locking this way means that the commit to disk code in
+ * the page cache code paths is automatically sufficiently locked with us as
+ * we will not touch a page that has been locked or is not uptodate. The only
+ * locking problem then is them locking the page while we are accessing it.
+ *
+ * So that code will end up having to own the mrec_lock of all mft
+ * records/inodes present in the page before I/O can proceed. In that case we
+ * wouldn't need to bother with PG_locked and PG_uptodate as nobody will be
+ * accessing anything without owning the mrec_lock mutex.  But we do need to
+ * use them because of the read_cache_page() invocation and the code becomes so
+ * much simpler this way that it is well worth it.
+ *
+ * The mft record is now ours and we return a pointer to it. You need to check
+ * the returned pointer with IS_ERR() and if that is true, PTR_ERR() will return
+ * the error code.
+ *
+ * NOTE: Caller is responsible for setting the mft record dirty before calling
+ * unmap_mft_record(). This is obviously only necessary if the caller really
+ * modified the mft record...
+ * Q: Do we want to recycle one of the VFS inode state bits instead?
+ * A: No, the inode ones mean we want to change the mft record, not we want to
+ * write it out.
+ */
+MFT_RECORD *map_mft_record(ntfs_inode *ni)
+{
+	MFT_RECORD *m;
+
+	ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no);
+
+	/* Make sure the ntfs inode doesn't go away. */
+	atomic_inc(&ni->count);
+
+	/* Serialize access to this mft record. */
+	mutex_lock(&ni->mrec_lock);
+
+	m = map_mft_record_page(ni);
+	if (likely(!IS_ERR(m)))
+		return m;
+
+	mutex_unlock(&ni->mrec_lock);
+	atomic_dec(&ni->count);
+	ntfs_error(ni->vol->sb, "Failed with error code %lu.", -PTR_ERR(m));
+	return m;
+}
+
+/**
+ * unmap_mft_record_page - unmap the page in which a specific mft record resides
+ * @ni:		ntfs inode whose mft record page to unmap
+ *
+ * This unmaps the page in which the mft record of the ntfs inode @ni is
+ * situated and returns. This is a NOOP if highmem is not configured.
+ *
+ * The unmap happens via ntfs_unmap_page() which in turn decrements the use
+ * count on the page thus releasing it from the pinned state.
+ *
+ * We do not actually unmap the page from memory of course, as that will be
+ * done by the page cache code itself when memory pressure increases or
+ * whatever.
+ */
+static inline void unmap_mft_record_page(ntfs_inode *ni)
+{
+	BUG_ON(!ni->page);
+
+	// TODO: If dirty, blah...
+	ntfs_unmap_page(ni->page);
+	ni->page = NULL;
+	ni->page_ofs = 0;
+	return;
+}
+
+/**
+ * unmap_mft_record - release a mapped mft record
+ * @ni:		ntfs inode whose MFT record to unmap
+ *
+ * We release the page mapping and the mrec_lock mutex which unmaps the mft
+ * record and releases it for others to get hold of. We also release the ntfs
+ * inode by decrementing the ntfs inode reference count.
+ *
+ * NOTE: If caller has modified the mft record, it is imperative to set the mft
+ * record dirty BEFORE calling unmap_mft_record().
+ */
+void unmap_mft_record(ntfs_inode *ni)
+{
+	struct page *page = ni->page;
+
+	BUG_ON(!page);
+
+	ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no);
+
+	unmap_mft_record_page(ni);
+	mutex_unlock(&ni->mrec_lock);
+	atomic_dec(&ni->count);
+	/*
+	 * If pure ntfs_inode, i.e. no vfs inode attached, we leave it to
+	 * ntfs_clear_extent_inode() in the extent inode case, and to the
+	 * caller in the non-extent, yet pure ntfs inode case, to do the actual
+	 * tear down of all structures and freeing of all allocated memory.
+	 */
+	return;
+}
+
+/**
+ * map_extent_mft_record - load an extent inode and attach it to its base
+ * @base_ni:	base ntfs inode
+ * @mref:	mft reference of the extent inode to load
+ * @ntfs_ino:	on successful return, pointer to the ntfs_inode structure
+ *
+ * Load the extent mft record @mref and attach it to its base inode @base_ni.
+ * Return the mapped extent mft record if IS_ERR(result) is false.  Otherwise
+ * PTR_ERR(result) gives the negative error code.
+ *
+ * On successful return, @ntfs_ino contains a pointer to the ntfs_inode
+ * structure of the mapped extent inode.
+ */
+MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
+		ntfs_inode **ntfs_ino)
+{
+	MFT_RECORD *m;
+	ntfs_inode *ni = NULL;
+	ntfs_inode **extent_nis = NULL;
+	int i;
+	unsigned long mft_no = MREF(mref);
+	u16 seq_no = MSEQNO(mref);
+	bool destroy_ni = false;
+
+	ntfs_debug("Mapping extent mft record 0x%lx (base mft record 0x%lx).",
+			mft_no, base_ni->mft_no);
+	/* Make sure the base ntfs inode doesn't go away. */
+	atomic_inc(&base_ni->count);
+	/*
+	 * Check if this extent inode has already been added to the base inode,
+	 * in which case just return it. If not found, add it to the base
+	 * inode before returning it.
+	 */
+	mutex_lock(&base_ni->extent_lock);
+	if (base_ni->nr_extents > 0) {
+		extent_nis = base_ni->ext.extent_ntfs_inos;
+		for (i = 0; i < base_ni->nr_extents; i++) {
+			if (mft_no != extent_nis[i]->mft_no)
+				continue;
+			ni = extent_nis[i];
+			/* Make sure the ntfs inode doesn't go away. */
+			atomic_inc(&ni->count);
+			break;
+		}
+	}
+	if (likely(ni != NULL)) {
+		mutex_unlock(&base_ni->extent_lock);
+		atomic_dec(&base_ni->count);
+		/* We found the record; just have to map and return it. */
+		m = map_mft_record(ni);
+		/* map_mft_record() has incremented this on success. */
+		atomic_dec(&ni->count);
+		if (likely(!IS_ERR(m))) {
+			/* Verify the sequence number. */
+			if (likely(le16_to_cpu(m->sequence_number) == seq_no)) {
+				ntfs_debug("Done 1.");
+				*ntfs_ino = ni;
+				return m;
+			}
+			unmap_mft_record(ni);
+			ntfs_error(base_ni->vol->sb, "Found stale extent mft "
+					"reference! Corrupt filesystem. "
+					"Run chkdsk.");
+			return ERR_PTR(-EIO);
+		}
+map_err_out:
+		ntfs_error(base_ni->vol->sb, "Failed to map extent "
+				"mft record, error code %ld.", -PTR_ERR(m));
+		return m;
+	}
+	/* Record wasn't there. Get a new ntfs inode and initialize it. */
+	ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no);
+	if (unlikely(!ni)) {
+		mutex_unlock(&base_ni->extent_lock);
+		atomic_dec(&base_ni->count);
+		return ERR_PTR(-ENOMEM);
+	}
+	ni->vol = base_ni->vol;
+	ni->seq_no = seq_no;
+	ni->nr_extents = -1;
+	ni->ext.base_ntfs_ino = base_ni;
+	/* Now map the record. */
+	m = map_mft_record(ni);
+	if (IS_ERR(m)) {
+		mutex_unlock(&base_ni->extent_lock);
+		atomic_dec(&base_ni->count);
+		ntfs_clear_extent_inode(ni);
+		goto map_err_out;
+	}
+	/* Verify the sequence number if it is present. */
+	if (seq_no && (le16_to_cpu(m->sequence_number) != seq_no)) {
+		ntfs_error(base_ni->vol->sb, "Found stale extent mft "
+				"reference! Corrupt filesystem. Run chkdsk.");
+		destroy_ni = true;
+		m = ERR_PTR(-EIO);
+		goto unm_err_out;
+	}
+	/* Attach extent inode to base inode, reallocating memory if needed. */
+	if (!(base_ni->nr_extents & 3)) {
+		ntfs_inode **tmp;
+		int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *);
+
+		tmp = kmalloc(new_size, GFP_NOFS);
+		if (unlikely(!tmp)) {
+			ntfs_error(base_ni->vol->sb, "Failed to allocate "
+					"internal buffer.");
+			destroy_ni = true;
+			m = ERR_PTR(-ENOMEM);
+			goto unm_err_out;
+		}
+		if (base_ni->nr_extents) {
+			BUG_ON(!base_ni->ext.extent_ntfs_inos);
+			memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size -
+					4 * sizeof(ntfs_inode *));
+			kfree(base_ni->ext.extent_ntfs_inos);
+		}
+		base_ni->ext.extent_ntfs_inos = tmp;
+	}
+	base_ni->ext.extent_ntfs_inos[base_ni->nr_extents++] = ni;
+	mutex_unlock(&base_ni->extent_lock);
+	atomic_dec(&base_ni->count);
+	ntfs_debug("Done 2.");
+	*ntfs_ino = ni;
+	return m;
+unm_err_out:
+	unmap_mft_record(ni);
+	mutex_unlock(&base_ni->extent_lock);
+	atomic_dec(&base_ni->count);
+	/*
+	 * If the extent inode was not attached to the base inode we need to
+	 * release it or we will leak memory.
+	 */
+	if (destroy_ni)
+		ntfs_clear_extent_inode(ni);
+	return m;
+}
+
+#ifdef NTFS_RW
+
+/**
+ * __mark_mft_record_dirty - set the mft record and the page containing it dirty
+ * @ni:		ntfs inode describing the mapped mft record
+ *
+ * Internal function.  Users should call mark_mft_record_dirty() instead.
+ *
+ * Set the mapped (extent) mft record of the (base or extent) ntfs inode @ni,
+ * as well as the page containing the mft record, dirty.  Also, mark the base
+ * vfs inode dirty.  This ensures that any changes to the mft record are
+ * written out to disk.
+ *
+ * NOTE:  We only set I_DIRTY_SYNC and I_DIRTY_DATASYNC (and not I_DIRTY_PAGES)
+ * on the base vfs inode, because even though file data may have been modified,
+ * it is dirty in the inode meta data rather than the data page cache of the
+ * inode, and thus there are no data pages that need writing out.  Therefore, a
+ * full mark_inode_dirty() is overkill.  A mark_inode_dirty_sync(), on the
+ * other hand, is not sufficient, because ->write_inode needs to be called even
+ * in case of fdatasync. This needs to happen or the file data would not
+ * necessarily hit the device synchronously, even though the vfs inode has the
+ * O_SYNC flag set.  Also, I_DIRTY_DATASYNC simply "feels" better than just
+ * I_DIRTY_SYNC, since the file data has not actually hit the block device yet,
+ * which is not what I_DIRTY_SYNC on its own would suggest.
+ */
+void __mark_mft_record_dirty(ntfs_inode *ni)
+{
+	ntfs_inode *base_ni;
+
+	ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
+	BUG_ON(NInoAttr(ni));
+	mark_ntfs_record_dirty(ni->page, ni->page_ofs);
+	/* Determine the base vfs inode and mark it dirty, too. */
+	mutex_lock(&ni->extent_lock);
+	if (likely(ni->nr_extents >= 0))
+		base_ni = ni;
+	else
+		base_ni = ni->ext.base_ntfs_ino;
+	mutex_unlock(&ni->extent_lock);
+	__mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC);
+}
+
+static const char *ntfs_please_email = "Please email "
+		"linux-ntfs-dev@lists.sourceforge.net and say that you saw "
+		"this message.  Thank you.";
+
+/**
+ * ntfs_sync_mft_mirror_umount - synchronise an mft record to the mft mirror
+ * @vol:	ntfs volume on which the mft record to synchronize resides
+ * @mft_no:	mft record number of mft record to synchronize
+ * @m:		mapped, mst protected (extent) mft record to synchronize
+ *
+ * Write the mapped, mst protected (extent) mft record @m with mft record
+ * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol,
+ * bypassing the page cache and the $MFTMirr inode itself.
+ *
+ * This function is only for use at umount time when the mft mirror inode has
+ * already been disposed off.  We BUG() if we are called while the mft mirror
+ * inode is still attached to the volume.
+ *
+ * On success return 0.  On error return -errno.
+ *
+ * NOTE:  This function is not implemented yet as I am not convinced it can
+ * actually be triggered considering the sequence of commits we do in super.c::
+ * ntfs_put_super().  But just in case we provide this place holder as the
+ * alternative would be either to BUG() or to get a NULL pointer dereference
+ * and Oops.
+ */
+static int ntfs_sync_mft_mirror_umount(ntfs_volume *vol,
+		const unsigned long mft_no, MFT_RECORD *m)
+{
+	BUG_ON(vol->mftmirr_ino);
+	ntfs_error(vol->sb, "Umount time mft mirror syncing is not "
+			"implemented yet.  %s", ntfs_please_email);
+	return -EOPNOTSUPP;
+}
+
+/**
+ * ntfs_sync_mft_mirror - synchronize an mft record to the mft mirror
+ * @vol:	ntfs volume on which the mft record to synchronize resides
+ * @mft_no:	mft record number of mft record to synchronize
+ * @m:		mapped, mst protected (extent) mft record to synchronize
+ * @sync:	if true, wait for i/o completion
+ *
+ * Write the mapped, mst protected (extent) mft record @m with mft record
+ * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol.
+ *
+ * On success return 0.  On error return -errno and set the volume errors flag
+ * in the ntfs volume @vol.
+ *
+ * NOTE:  We always perform synchronous i/o and ignore the @sync parameter.
+ *
+ * TODO:  If @sync is false, want to do truly asynchronous i/o, i.e. just
+ * schedule i/o via ->writepage or do it via kntfsd or whatever.
+ */
+int ntfs_sync_mft_mirror(ntfs_volume *vol, const unsigned long mft_no,
+		MFT_RECORD *m, int sync)
+{
+	struct page *page;
+	unsigned int blocksize = vol->sb->s_blocksize;
+	int max_bhs = vol->mft_record_size / blocksize;
+	struct buffer_head *bhs[max_bhs];
+	struct buffer_head *bh, *head;
+	u8 *kmirr;
+	runlist_element *rl;
+	unsigned int block_start, block_end, m_start, m_end, page_ofs;
+	int i_bhs, nr_bhs, err = 0;
+	unsigned char blocksize_bits = vol->sb->s_blocksize_bits;
+
+	ntfs_debug("Entering for inode 0x%lx.", mft_no);
+	BUG_ON(!max_bhs);
+	if (unlikely(!vol->mftmirr_ino)) {
+		/* This could happen during umount... */
+		err = ntfs_sync_mft_mirror_umount(vol, mft_no, m);
+		if (likely(!err))
+			return err;
+		goto err_out;
+	}
+	/* Get the page containing the mirror copy of the mft record @m. */
+	page = ntfs_map_page(vol->mftmirr_ino->i_mapping, mft_no >>
+			(PAGE_CACHE_SHIFT - vol->mft_record_size_bits));
+	if (IS_ERR(page)) {
+		ntfs_error(vol->sb, "Failed to map mft mirror page.");
+		err = PTR_ERR(page);
+		goto err_out;
+	}
+	lock_page(page);
+	BUG_ON(!PageUptodate(page));
+	ClearPageUptodate(page);
+	/* Offset of the mft mirror record inside the page. */
+	page_ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
+	/* The address in the page of the mirror copy of the mft record @m. */
+	kmirr = page_address(page) + page_ofs;
+	/* Copy the mst protected mft record to the mirror. */
+	memcpy(kmirr, m, vol->mft_record_size);
+	/* Create uptodate buffers if not present. */
+	if (unlikely(!page_has_buffers(page))) {
+		struct buffer_head *tail;
+
+		bh = head = alloc_page_buffers(page, blocksize, 1);
+		do {
+			set_buffer_uptodate(bh);
+			tail = bh;
+			bh = bh->b_this_page;
+		} while (bh);
+		tail->b_this_page = head;
+		attach_page_buffers(page, head);
+	}
+	bh = head = page_buffers(page);
+	BUG_ON(!bh);
+	rl = NULL;
+	nr_bhs = 0;
+	block_start = 0;
+	m_start = kmirr - (u8*)page_address(page);
+	m_end = m_start + vol->mft_record_size;
+	do {
+		block_end = block_start + blocksize;
+		/* If the buffer is outside the mft record, skip it. */
+		if (block_end <= m_start)
+			continue;
+		if (unlikely(block_start >= m_end))
+			break;
+		/* Need to map the buffer if it is not mapped already. */
+		if (unlikely(!buffer_mapped(bh))) {
+			VCN vcn;
+			LCN lcn;
+			unsigned int vcn_ofs;
+
+			bh->b_bdev = vol->sb->s_bdev;
+			/* Obtain the vcn and offset of the current block. */
+			vcn = ((VCN)mft_no << vol->mft_record_size_bits) +
+					(block_start - m_start);
+			vcn_ofs = vcn & vol->cluster_size_mask;
+			vcn >>= vol->cluster_size_bits;
+			if (!rl) {
+				down_read(&NTFS_I(vol->mftmirr_ino)->
+						runlist.lock);
+				rl = NTFS_I(vol->mftmirr_ino)->runlist.rl;
+				/*
+				 * $MFTMirr always has the whole of its runlist
+				 * in memory.
+				 */
+				BUG_ON(!rl);
+			}
+			/* Seek to element containing target vcn. */
+			while (rl->length && rl[1].vcn <= vcn)
+				rl++;
+			lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
+			/* For $MFTMirr, only lcn >= 0 is a successful remap. */
+			if (likely(lcn >= 0)) {
+				/* Setup buffer head to correct block. */
+				bh->b_blocknr = ((lcn <<
+						vol->cluster_size_bits) +
+						vcn_ofs) >> blocksize_bits;
+				set_buffer_mapped(bh);
+			} else {
+				bh->b_blocknr = -1;
+				ntfs_error(vol->sb, "Cannot write mft mirror "
+						"record 0x%lx because its "
+						"location on disk could not "
+						"be determined (error code "
+						"%lli).", mft_no,
+						(long long)lcn);
+				err = -EIO;
+			}
+		}
+		BUG_ON(!buffer_uptodate(bh));
+		BUG_ON(!nr_bhs && (m_start != block_start));
+		BUG_ON(nr_bhs >= max_bhs);
+		bhs[nr_bhs++] = bh;
+		BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
+	} while (block_start = block_end, (bh = bh->b_this_page) != head);
+	if (unlikely(rl))
+		up_read(&NTFS_I(vol->mftmirr_ino)->runlist.lock);
+	if (likely(!err)) {
+		/* Lock buffers and start synchronous write i/o on them. */
+		for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
+			struct buffer_head *tbh = bhs[i_bhs];
+
+			if (!trylock_buffer(tbh))
+				BUG();
+			BUG_ON(!buffer_uptodate(tbh));
+			clear_buffer_dirty(tbh);
+			get_bh(tbh);
+			tbh->b_end_io = end_buffer_write_sync;
+			submit_bh(WRITE, tbh);
+		}
+		/* Wait on i/o completion of buffers. */
+		for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
+			struct buffer_head *tbh = bhs[i_bhs];
+
+			wait_on_buffer(tbh);
+			if (unlikely(!buffer_uptodate(tbh))) {
+				err = -EIO;
+				/*
+				 * Set the buffer uptodate so the page and
+				 * buffer states do not become out of sync.
+				 */
+				set_buffer_uptodate(tbh);
+			}
+		}
+	} else /* if (unlikely(err)) */ {
+		/* Clean the buffers. */
+		for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
+			clear_buffer_dirty(bhs[i_bhs]);
+	}
+	/* Current state: all buffers are clean, unlocked, and uptodate. */
+	/* Remove the mst protection fixups again. */
+	post_write_mst_fixup((NTFS_RECORD*)kmirr);
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	unlock_page(page);
+	ntfs_unmap_page(page);
+	if (likely(!err)) {
+		ntfs_debug("Done.");
+	} else {
+		ntfs_error(vol->sb, "I/O error while writing mft mirror "
+				"record 0x%lx!", mft_no);
+err_out:
+		ntfs_error(vol->sb, "Failed to synchronize $MFTMirr (error "
+				"code %i).  Volume will be left marked dirty "
+				"on umount.  Run ntfsfix on the partition "
+				"after umounting to correct this.", -err);
+		NVolSetErrors(vol);
+	}
+	return err;
+}
+
+/**
+ * write_mft_record_nolock - write out a mapped (extent) mft record
+ * @ni:		ntfs inode describing the mapped (extent) mft record
+ * @m:		mapped (extent) mft record to write
+ * @sync:	if true, wait for i/o completion
+ *
+ * Write the mapped (extent) mft record @m described by the (regular or extent)
+ * ntfs inode @ni to backing store.  If the mft record @m has a counterpart in
+ * the mft mirror, that is also updated.
+ *
+ * We only write the mft record if the ntfs inode @ni is dirty and the first
+ * buffer belonging to its mft record is dirty, too.  We ignore the dirty state
+ * of subsequent buffers because we could have raced with
+ * fs/ntfs/aops.c::mark_ntfs_record_dirty().
+ *
+ * On success, clean the mft record and return 0.  On error, leave the mft
+ * record dirty and return -errno.
+ *
+ * NOTE:  We always perform synchronous i/o and ignore the @sync parameter.
+ * However, if the mft record has a counterpart in the mft mirror and @sync is
+ * true, we write the mft record, wait for i/o completion, and only then write
+ * the mft mirror copy.  This ensures that if the system crashes either the mft
+ * or the mft mirror will contain a self-consistent mft record @m.  If @sync is
+ * false on the other hand, we start i/o on both and then wait for completion
+ * on them.  This provides a speedup but no longer guarantees that you will end
+ * up with a self-consistent mft record in the case of a crash but if you asked
+ * for asynchronous writing you probably do not care about that anyway.
+ *
+ * TODO:  If @sync is false, want to do truly asynchronous i/o, i.e. just
+ * schedule i/o via ->writepage or do it via kntfsd or whatever.
+ */
+int write_mft_record_nolock(ntfs_inode *ni, MFT_RECORD *m, int sync)
+{
+	ntfs_volume *vol = ni->vol;
+	struct page *page = ni->page;
+	unsigned int blocksize = vol->sb->s_blocksize;
+	unsigned char blocksize_bits = vol->sb->s_blocksize_bits;
+	int max_bhs = vol->mft_record_size / blocksize;
+	struct buffer_head *bhs[max_bhs];
+	struct buffer_head *bh, *head;
+	runlist_element *rl;
+	unsigned int block_start, block_end, m_start, m_end;
+	int i_bhs, nr_bhs, err = 0;
+
+	ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
+	BUG_ON(NInoAttr(ni));
+	BUG_ON(!max_bhs);
+	BUG_ON(!PageLocked(page));
+	/*
+	 * If the ntfs_inode is clean no need to do anything.  If it is dirty,
+	 * mark it as clean now so that it can be redirtied later on if needed.
+	 * There is no danger of races since the caller is holding the locks
+	 * for the mft record @m and the page it is in.
+	 */
+	if (!NInoTestClearDirty(ni))
+		goto done;
+	bh = head = page_buffers(page);
+	BUG_ON(!bh);
+	rl = NULL;
+	nr_bhs = 0;
+	block_start = 0;
+	m_start = ni->page_ofs;
+	m_end = m_start + vol->mft_record_size;
+	do {
+		block_end = block_start + blocksize;
+		/* If the buffer is outside the mft record, skip it. */
+		if (block_end <= m_start)
+			continue;
+		if (unlikely(block_start >= m_end))
+			break;
+		/*
+		 * If this block is not the first one in the record, we ignore
+		 * the buffer's dirty state because we could have raced with a
+		 * parallel mark_ntfs_record_dirty().
+		 */
+		if (block_start == m_start) {
+			/* This block is the first one in the record. */
+			if (!buffer_dirty(bh)) {
+				BUG_ON(nr_bhs);
+				/* Clean records are not written out. */
+				break;
+			}
+		}
+		/* Need to map the buffer if it is not mapped already. */
+		if (unlikely(!buffer_mapped(bh))) {
+			VCN vcn;
+			LCN lcn;
+			unsigned int vcn_ofs;
+
+			bh->b_bdev = vol->sb->s_bdev;
+			/* Obtain the vcn and offset of the current block. */
+			vcn = ((VCN)ni->mft_no << vol->mft_record_size_bits) +
+					(block_start - m_start);
+			vcn_ofs = vcn & vol->cluster_size_mask;
+			vcn >>= vol->cluster_size_bits;
+			if (!rl) {
+				down_read(&NTFS_I(vol->mft_ino)->runlist.lock);
+				rl = NTFS_I(vol->mft_ino)->runlist.rl;
+				BUG_ON(!rl);
+			}
+			/* Seek to element containing target vcn. */
+			while (rl->length && rl[1].vcn <= vcn)
+				rl++;
+			lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
+			/* For $MFT, only lcn >= 0 is a successful remap. */
+			if (likely(lcn >= 0)) {
+				/* Setup buffer head to correct block. */
+				bh->b_blocknr = ((lcn <<
+						vol->cluster_size_bits) +
+						vcn_ofs) >> blocksize_bits;
+				set_buffer_mapped(bh);
+			} else {
+				bh->b_blocknr = -1;
+				ntfs_error(vol->sb, "Cannot write mft record "
+						"0x%lx because its location "
+						"on disk could not be "
+						"determined (error code %lli).",
+						ni->mft_no, (long long)lcn);
+				err = -EIO;
+			}
+		}
+		BUG_ON(!buffer_uptodate(bh));
+		BUG_ON(!nr_bhs && (m_start != block_start));
+		BUG_ON(nr_bhs >= max_bhs);
+		bhs[nr_bhs++] = bh;
+		BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
+	} while (block_start = block_end, (bh = bh->b_this_page) != head);
+	if (unlikely(rl))
+		up_read(&NTFS_I(vol->mft_ino)->runlist.lock);
+	if (!nr_bhs)
+		goto done;
+	if (unlikely(err))
+		goto cleanup_out;
+	/* Apply the mst protection fixups. */
+	err = pre_write_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size);
+	if (err) {
+		ntfs_error(vol->sb, "Failed to apply mst fixups!");
+		goto cleanup_out;
+	}
+	flush_dcache_mft_record_page(ni);
+	/* Lock buffers and start synchronous write i/o on them. */
+	for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
+		struct buffer_head *tbh = bhs[i_bhs];
+
+		if (!trylock_buffer(tbh))
+			BUG();
+		BUG_ON(!buffer_uptodate(tbh));
+		clear_buffer_dirty(tbh);
+		get_bh(tbh);
+		tbh->b_end_io = end_buffer_write_sync;
+		submit_bh(WRITE, tbh);
+	}
+	/* Synchronize the mft mirror now if not @sync. */
+	if (!sync && ni->mft_no < vol->mftmirr_size)
+		ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
+	/* Wait on i/o completion of buffers. */
+	for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
+		struct buffer_head *tbh = bhs[i_bhs];
+
+		wait_on_buffer(tbh);
+		if (unlikely(!buffer_uptodate(tbh))) {
+			err = -EIO;
+			/*
+			 * Set the buffer uptodate so the page and buffer
+			 * states do not become out of sync.
+			 */
+			if (PageUptodate(page))
+				set_buffer_uptodate(tbh);
+		}
+	}
+	/* If @sync, now synchronize the mft mirror. */
+	if (sync && ni->mft_no < vol->mftmirr_size)
+		ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
+	/* Remove the mst protection fixups again. */
+	post_write_mst_fixup((NTFS_RECORD*)m);
+	flush_dcache_mft_record_page(ni);
+	if (unlikely(err)) {
+		/* I/O error during writing.  This is really bad! */
+		ntfs_error(vol->sb, "I/O error while writing mft record "
+				"0x%lx!  Marking base inode as bad.  You "
+				"should unmount the volume and run chkdsk.",
+				ni->mft_no);
+		goto err_out;
+	}
+done:
+	ntfs_debug("Done.");
+	return 0;
+cleanup_out:
+	/* Clean the buffers. */
+	for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
+		clear_buffer_dirty(bhs[i_bhs]);
+err_out:
+	/*
+	 * Current state: all buffers are clean, unlocked, and uptodate.
+	 * The caller should mark the base inode as bad so that no more i/o
+	 * happens.  ->clear_inode() will still be invoked so all extent inodes
+	 * and other allocated memory will be freed.
+	 */
+	if (err == -ENOMEM) {
+		ntfs_error(vol->sb, "Not enough memory to write mft record.  "
+				"Redirtying so the write is retried later.");
+		mark_mft_record_dirty(ni);
+		err = 0;
+	} else
+		NVolSetErrors(vol);
+	return err;
+}
+
+/**
+ * ntfs_may_write_mft_record - check if an mft record may be written out
+ * @vol:	[IN]  ntfs volume on which the mft record to check resides
+ * @mft_no:	[IN]  mft record number of the mft record to check
+ * @m:		[IN]  mapped mft record to check
+ * @locked_ni:	[OUT] caller has to unlock this ntfs inode if one is returned
+ *
+ * Check if the mapped (base or extent) mft record @m with mft record number
+ * @mft_no belonging to the ntfs volume @vol may be written out.  If necessary
+ * and possible the ntfs inode of the mft record is locked and the base vfs
+ * inode is pinned.  The locked ntfs inode is then returned in @locked_ni.  The
+ * caller is responsible for unlocking the ntfs inode and unpinning the base
+ * vfs inode.
+ *
+ * Return 'true' if the mft record may be written out and 'false' if not.
+ *
+ * The caller has locked the page and cleared the uptodate flag on it which
+ * means that we can safely write out any dirty mft records that do not have
+ * their inodes in icache as determined by ilookup5() as anyone
+ * opening/creating such an inode would block when attempting to map the mft
+ * record in read_cache_page() until we are finished with the write out.
+ *
+ * Here is a description of the tests we perform:
+ *
+ * If the inode is found in icache we know the mft record must be a base mft
+ * record.  If it is dirty, we do not write it and return 'false' as the vfs
+ * inode write paths will result in the access times being updated which would
+ * cause the base mft record to be redirtied and written out again.  (We know
+ * the access time update will modify the base mft record because Windows
+ * chkdsk complains if the standard information attribute is not in the base
+ * mft record.)
+ *
+ * If the inode is in icache and not dirty, we attempt to lock the mft record
+ * and if we find the lock was already taken, it is not safe to write the mft
+ * record and we return 'false'.
+ *
+ * If we manage to obtain the lock we have exclusive access to the mft record,
+ * which also allows us safe writeout of the mft record.  We then set
+ * @locked_ni to the locked ntfs inode and return 'true'.
+ *
+ * Note we cannot just lock the mft record and sleep while waiting for the lock
+ * because this would deadlock due to lock reversal (normally the mft record is
+ * locked before the page is locked but we already have the page locked here
+ * when we try to lock the mft record).
+ *
+ * If the inode is not in icache we need to perform further checks.
+ *
+ * If the mft record is not a FILE record or it is a base mft record, we can
+ * safely write it and return 'true'.
+ *
+ * We now know the mft record is an extent mft record.  We check if the inode
+ * corresponding to its base mft record is in icache and obtain a reference to
+ * it if it is.  If it is not, we can safely write it and return 'true'.
+ *
+ * We now have the base inode for the extent mft record.  We check if it has an
+ * ntfs inode for the extent mft record attached and if not it is safe to write
+ * the extent mft record and we return 'true'.
+ *
+ * The ntfs inode for the extent mft record is attached to the base inode so we
+ * attempt to lock the extent mft record and if we find the lock was already
+ * taken, it is not safe to write the extent mft record and we return 'false'.
+ *
+ * If we manage to obtain the lock we have exclusive access to the extent mft
+ * record, which also allows us safe writeout of the extent mft record.  We
+ * set the ntfs inode of the extent mft record clean and then set @locked_ni to
+ * the now locked ntfs inode and return 'true'.
+ *
+ * Note, the reason for actually writing dirty mft records here and not just
+ * relying on the vfs inode dirty code paths is that we can have mft records
+ * modified without them ever having actual inodes in memory.  Also we can have
+ * dirty mft records with clean ntfs inodes in memory.  None of the described
+ * cases would result in the dirty mft records being written out if we only
+ * relied on the vfs inode dirty code paths.  And these cases can really occur
+ * during allocation of new mft records and in particular when the
+ * initialized_size of the $MFT/$DATA attribute is extended and the new space
+ * is initialized using ntfs_mft_record_format().  The clean inode can then
+ * appear if the mft record is reused for a new inode before it got written
+ * out.
+ */
+bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
+		const MFT_RECORD *m, ntfs_inode **locked_ni)
+{
+	struct super_block *sb = vol->sb;
+	struct inode *mft_vi = vol->mft_ino;
+	struct inode *vi;
+	ntfs_inode *ni, *eni, **extent_nis;
+	int i;
+	ntfs_attr na;
+
+	ntfs_debug("Entering for inode 0x%lx.", mft_no);
+	/*
+	 * Normally we do not return a locked inode so set @locked_ni to NULL.
+	 */
+	BUG_ON(!locked_ni);
+	*locked_ni = NULL;
+	/*
+	 * Check if the inode corresponding to this mft record is in the VFS
+	 * inode cache and obtain a reference to it if it is.
+	 */
+	ntfs_debug("Looking for inode 0x%lx in icache.", mft_no);
+	na.mft_no = mft_no;
+	na.name = NULL;
+	na.name_len = 0;
+	na.type = AT_UNUSED;
+	/*
+	 * Optimize inode 0, i.e. $MFT itself, since we have it in memory and
+	 * we get here for it rather often.
+	 */
+	if (!mft_no) {
+		/* Balance the below iput(). */
+		vi = igrab(mft_vi);
+		BUG_ON(vi != mft_vi);
+	} else {
+		/*
+		 * Have to use ilookup5_nowait() since ilookup5() waits for the
+		 * inode lock which causes ntfs to deadlock when a concurrent
+		 * inode write via the inode dirty code paths and the page
+		 * dirty code path of the inode dirty code path when writing
+		 * $MFT occurs.
+		 */
+		vi = ilookup5_nowait(sb, mft_no, (test_t)ntfs_test_inode, &na);
+	}
+	if (vi) {
+		ntfs_debug("Base inode 0x%lx is in icache.", mft_no);
+		/* The inode is in icache. */
+		ni = NTFS_I(vi);
+		/* Take a reference to the ntfs inode. */
+		atomic_inc(&ni->count);
+		/* If the inode is dirty, do not write this record. */
+		if (NInoDirty(ni)) {
+			ntfs_debug("Inode 0x%lx is dirty, do not write it.",
+					mft_no);
+			atomic_dec(&ni->count);
+			iput(vi);
+			return false;
+		}
+		ntfs_debug("Inode 0x%lx is not dirty.", mft_no);
+		/* The inode is not dirty, try to take the mft record lock. */
+		if (unlikely(!mutex_trylock(&ni->mrec_lock))) {
+			ntfs_debug("Mft record 0x%lx is already locked, do "
+					"not write it.", mft_no);
+			atomic_dec(&ni->count);
+			iput(vi);
+			return false;
+		}
+		ntfs_debug("Managed to lock mft record 0x%lx, write it.",
+				mft_no);
+		/*
+		 * The write has to occur while we hold the mft record lock so
+		 * return the locked ntfs inode.
+		 */
+		*locked_ni = ni;
+		return true;
+	}
+	ntfs_debug("Inode 0x%lx is not in icache.", mft_no);
+	/* The inode is not in icache. */
+	/* Write the record if it is not a mft record (type "FILE"). */
+	if (!ntfs_is_mft_record(m->magic)) {
+		ntfs_debug("Mft record 0x%lx is not a FILE record, write it.",
+				mft_no);
+		return true;
+	}
+	/* Write the mft record if it is a base inode. */
+	if (!m->base_mft_record) {
+		ntfs_debug("Mft record 0x%lx is a base record, write it.",
+				mft_no);
+		return true;
+	}
+	/*
+	 * This is an extent mft record.  Check if the inode corresponding to
+	 * its base mft record is in icache and obtain a reference to it if it
+	 * is.
+	 */
+	na.mft_no = MREF_LE(m->base_mft_record);
+	ntfs_debug("Mft record 0x%lx is an extent record.  Looking for base "
+			"inode 0x%lx in icache.", mft_no, na.mft_no);
+	if (!na.mft_no) {
+		/* Balance the below iput(). */
+		vi = igrab(mft_vi);
+		BUG_ON(vi != mft_vi);
+	} else
+		vi = ilookup5_nowait(sb, na.mft_no, (test_t)ntfs_test_inode,
+				&na);
+	if (!vi) {
+		/*
+		 * The base inode is not in icache, write this extent mft
+		 * record.
+		 */
+		ntfs_debug("Base inode 0x%lx is not in icache, write the "
+				"extent record.", na.mft_no);
+		return true;
+	}
+	ntfs_debug("Base inode 0x%lx is in icache.", na.mft_no);
+	/*
+	 * The base inode is in icache.  Check if it has the extent inode
+	 * corresponding to this extent mft record attached.
+	 */
+	ni = NTFS_I(vi);
+	mutex_lock(&ni->extent_lock);
+	if (ni->nr_extents <= 0) {
+		/*
+		 * The base inode has no attached extent inodes, write this
+		 * extent mft record.
+		 */
+		mutex_unlock(&ni->extent_lock);
+		iput(vi);
+		ntfs_debug("Base inode 0x%lx has no attached extent inodes, "
+				"write the extent record.", na.mft_no);
+		return true;
+	}
+	/* Iterate over the attached extent inodes. */
+	extent_nis = ni->ext.extent_ntfs_inos;
+	for (eni = NULL, i = 0; i < ni->nr_extents; ++i) {
+		if (mft_no == extent_nis[i]->mft_no) {
+			/*
+			 * Found the extent inode corresponding to this extent
+			 * mft record.
+			 */
+			eni = extent_nis[i];
+			break;
+		}
+	}
+	/*
+	 * If the extent inode was not attached to the base inode, write this
+	 * extent mft record.
+	 */
+	if (!eni) {
+		mutex_unlock(&ni->extent_lock);
+		iput(vi);
+		ntfs_debug("Extent inode 0x%lx is not attached to its base "
+				"inode 0x%lx, write the extent record.",
+				mft_no, na.mft_no);
+		return true;
+	}
+	ntfs_debug("Extent inode 0x%lx is attached to its base inode 0x%lx.",
+			mft_no, na.mft_no);
+	/* Take a reference to the extent ntfs inode. */
+	atomic_inc(&eni->count);
+	mutex_unlock(&ni->extent_lock);
+	/*
+	 * Found the extent inode coresponding to this extent mft record.
+	 * Try to take the mft record lock.
+	 */
+	if (unlikely(!mutex_trylock(&eni->mrec_lock))) {
+		atomic_dec(&eni->count);
+		iput(vi);
+		ntfs_debug("Extent mft record 0x%lx is already locked, do "
+				"not write it.", mft_no);
+		return false;
+	}
+	ntfs_debug("Managed to lock extent mft record 0x%lx, write it.",
+			mft_no);
+	if (NInoTestClearDirty(eni))
+		ntfs_debug("Extent inode 0x%lx is dirty, marking it clean.",
+				mft_no);
+	/*
+	 * The write has to occur while we hold the mft record lock so return
+	 * the locked extent ntfs inode.
+	 */
+	*locked_ni = eni;
+	return true;
+}
+
+static const char *es = "  Leaving inconsistent metadata.  Unmount and run "
+		"chkdsk.";
+
+/**
+ * ntfs_mft_bitmap_find_and_alloc_free_rec_nolock - see name
+ * @vol:	volume on which to search for a free mft record
+ * @base_ni:	open base inode if allocating an extent mft record or NULL
+ *
+ * Search for a free mft record in the mft bitmap attribute on the ntfs volume
+ * @vol.
+ *
+ * If @base_ni is NULL start the search at the default allocator position.
+ *
+ * If @base_ni is not NULL start the search at the mft record after the base
+ * mft record @base_ni.
+ *
+ * Return the free mft record on success and -errno on error.  An error code of
+ * -ENOSPC means that there are no free mft records in the currently
+ * initialized mft bitmap.
+ *
+ * Locking: Caller must hold vol->mftbmp_lock for writing.
+ */
+static int ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(ntfs_volume *vol,
+		ntfs_inode *base_ni)
+{
+	s64 pass_end, ll, data_pos, pass_start, ofs, bit;
+	unsigned long flags;
+	struct address_space *mftbmp_mapping;
+	u8 *buf, *byte;
+	struct page *page;
+	unsigned int page_ofs, size;
+	u8 pass, b;
+
+	ntfs_debug("Searching for free mft record in the currently "
+			"initialized mft bitmap.");
+	mftbmp_mapping = vol->mftbmp_ino->i_mapping;
+	/*
+	 * Set the end of the pass making sure we do not overflow the mft
+	 * bitmap.
+	 */
+	read_lock_irqsave(&NTFS_I(vol->mft_ino)->size_lock, flags);
+	pass_end = NTFS_I(vol->mft_ino)->allocated_size >>
+			vol->mft_record_size_bits;
+	read_unlock_irqrestore(&NTFS_I(vol->mft_ino)->size_lock, flags);
+	read_lock_irqsave(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
+	ll = NTFS_I(vol->mftbmp_ino)->initialized_size << 3;
+	read_unlock_irqrestore(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
+	if (pass_end > ll)
+		pass_end = ll;
+	pass = 1;
+	if (!base_ni)
+		data_pos = vol->mft_data_pos;
+	else
+		data_pos = base_ni->mft_no + 1;
+	if (data_pos < 24)
+		data_pos = 24;
+	if (data_pos >= pass_end) {
+		data_pos = 24;
+		pass = 2;
+		/* This happens on a freshly formatted volume. */
+		if (data_pos >= pass_end)
+			return -ENOSPC;
+	}
+	pass_start = data_pos;
+	ntfs_debug("Starting bitmap search: pass %u, pass_start 0x%llx, "
+			"pass_end 0x%llx, data_pos 0x%llx.", pass,
+			(long long)pass_start, (long long)pass_end,
+			(long long)data_pos);
+	/* Loop until a free mft record is found. */
+	for (; pass <= 2;) {
+		/* Cap size to pass_end. */
+		ofs = data_pos >> 3;
+		page_ofs = ofs & ~PAGE_CACHE_MASK;
+		size = PAGE_CACHE_SIZE - page_ofs;
+		ll = ((pass_end + 7) >> 3) - ofs;
+		if (size > ll)
+			size = ll;
+		size <<= 3;
+		/*
+		 * If we are still within the active pass, search the next page
+		 * for a zero bit.
+		 */
+		if (size) {
+			page = ntfs_map_page(mftbmp_mapping,
+					ofs >> PAGE_CACHE_SHIFT);
+			if (IS_ERR(page)) {
+				ntfs_error(vol->sb, "Failed to read mft "
+						"bitmap, aborting.");
+				return PTR_ERR(page);
+			}
+			buf = (u8*)page_address(page) + page_ofs;
+			bit = data_pos & 7;
+			data_pos &= ~7ull;
+			ntfs_debug("Before inner for loop: size 0x%x, "
+					"data_pos 0x%llx, bit 0x%llx", size,
+					(long long)data_pos, (long long)bit);
+			for (; bit < size && data_pos + bit < pass_end;
+					bit &= ~7ull, bit += 8) {
+				byte = buf + (bit >> 3);
+				if (*byte == 0xff)
+					continue;
+				b = ffz((unsigned long)*byte);
+				if (b < 8 && b >= (bit & 7)) {
+					ll = data_pos + (bit & ~7ull) + b;
+					if (unlikely(ll > (1ll << 32))) {
+						ntfs_unmap_page(page);
+						return -ENOSPC;
+					}
+					*byte |= 1 << b;
+					flush_dcache_page(page);
+					set_page_dirty(page);
+					ntfs_unmap_page(page);
+					ntfs_debug("Done.  (Found and "
+							"allocated mft record "
+							"0x%llx.)",
+							(long long)ll);
+					return ll;
+				}
+			}
+			ntfs_debug("After inner for loop: size 0x%x, "
+					"data_pos 0x%llx, bit 0x%llx", size,
+					(long long)data_pos, (long long)bit);
+			data_pos += size;
+			ntfs_unmap_page(page);
+			/*
+			 * If the end of the pass has not been reached yet,
+			 * continue searching the mft bitmap for a zero bit.
+			 */
+			if (data_pos < pass_end)
+				continue;
+		}
+		/* Do the next pass. */
+		if (++pass == 2) {
+			/*
+			 * Starting the second pass, in which we scan the first
+			 * part of the zone which we omitted earlier.
+			 */
+			pass_end = pass_start;
+			data_pos = pass_start = 24;
+			ntfs_debug("pass %i, pass_start 0x%llx, pass_end "
+					"0x%llx.", pass, (long long)pass_start,
+					(long long)pass_end);
+			if (data_pos >= pass_end)
+				break;
+		}
+	}
+	/* No free mft records in currently initialized mft bitmap. */
+	ntfs_debug("Done.  (No free mft records left in currently initialized "
+			"mft bitmap.)");
+	return -ENOSPC;
+}
+
+/**
+ * ntfs_mft_bitmap_extend_allocation_nolock - extend mft bitmap by a cluster
+ * @vol:	volume on which to extend the mft bitmap attribute
+ *
+ * Extend the mft bitmap attribute on the ntfs volume @vol by one cluster.
+ *
+ * Note: Only changes allocated_size, i.e. does not touch initialized_size or
+ * data_size.
+ *
+ * Return 0 on success and -errno on error.
+ *
+ * Locking: - Caller must hold vol->mftbmp_lock for writing.
+ *	    - This function takes NTFS_I(vol->mftbmp_ino)->runlist.lock for
+ *	      writing and releases it before returning.
+ *	    - This function takes vol->lcnbmp_lock for writing and releases it
+ *	      before returning.
+ */
+static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
+{
+	LCN lcn;
+	s64 ll;
+	unsigned long flags;
+	struct page *page;
+	ntfs_inode *mft_ni, *mftbmp_ni;
+	runlist_element *rl, *rl2 = NULL;
+	ntfs_attr_search_ctx *ctx = NULL;
+	MFT_RECORD *mrec;
+	ATTR_RECORD *a = NULL;
+	int ret, mp_size;
+	u32 old_alen = 0;
+	u8 *b, tb;
+	struct {
+		u8 added_cluster:1;
+		u8 added_run:1;
+		u8 mp_rebuilt:1;
+	} status = { 0, 0, 0 };
+
+	ntfs_debug("Extending mft bitmap allocation.");
+	mft_ni = NTFS_I(vol->mft_ino);
+	mftbmp_ni = NTFS_I(vol->mftbmp_ino);
+	/*
+	 * Determine the last lcn of the mft bitmap.  The allocated size of the
+	 * mft bitmap cannot be zero so we are ok to do this.
+	 */
+	down_write(&mftbmp_ni->runlist.lock);
+	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	ll = mftbmp_ni->allocated_size;
+	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	rl = ntfs_attr_find_vcn_nolock(mftbmp_ni,
+			(ll - 1) >> vol->cluster_size_bits, NULL);
+	if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
+		up_write(&mftbmp_ni->runlist.lock);
+		ntfs_error(vol->sb, "Failed to determine last allocated "
+				"cluster of mft bitmap attribute.");
+		if (!IS_ERR(rl))
+			ret = -EIO;
+		else
+			ret = PTR_ERR(rl);
+		return ret;
+	}
+	lcn = rl->lcn + rl->length;
+	ntfs_debug("Last lcn of mft bitmap attribute is 0x%llx.",
+			(long long)lcn);
+	/*
+	 * Attempt to get the cluster following the last allocated cluster by
+	 * hand as it may be in the MFT zone so the allocator would not give it
+	 * to us.
+	 */
+	ll = lcn >> 3;
+	page = ntfs_map_page(vol->lcnbmp_ino->i_mapping,
+			ll >> PAGE_CACHE_SHIFT);
+	if (IS_ERR(page)) {
+		up_write(&mftbmp_ni->runlist.lock);
+		ntfs_error(vol->sb, "Failed to read from lcn bitmap.");
+		return PTR_ERR(page);
+	}
+	b = (u8*)page_address(page) + (ll & ~PAGE_CACHE_MASK);
+	tb = 1 << (lcn & 7ull);
+	down_write(&vol->lcnbmp_lock);
+	if (*b != 0xff && !(*b & tb)) {
+		/* Next cluster is free, allocate it. */
+		*b |= tb;
+		flush_dcache_page(page);
+		set_page_dirty(page);
+		up_write(&vol->lcnbmp_lock);
+		ntfs_unmap_page(page);
+		/* Update the mft bitmap runlist. */
+		rl->length++;
+		rl[1].vcn++;
+		status.added_cluster = 1;
+		ntfs_debug("Appending one cluster to mft bitmap.");
+	} else {
+		up_write(&vol->lcnbmp_lock);
+		ntfs_unmap_page(page);
+		/* Allocate a cluster from the DATA_ZONE. */
+		rl2 = ntfs_cluster_alloc(vol, rl[1].vcn, 1, lcn, DATA_ZONE,
+				true);
+		if (IS_ERR(rl2)) {
+			up_write(&mftbmp_ni->runlist.lock);
+			ntfs_error(vol->sb, "Failed to allocate a cluster for "
+					"the mft bitmap.");
+			return PTR_ERR(rl2);
+		}
+		rl = ntfs_runlists_merge(mftbmp_ni->runlist.rl, rl2);
+		if (IS_ERR(rl)) {
+			up_write(&mftbmp_ni->runlist.lock);
+			ntfs_error(vol->sb, "Failed to merge runlists for mft "
+					"bitmap.");
+			if (ntfs_cluster_free_from_rl(vol, rl2)) {
+				ntfs_error(vol->sb, "Failed to deallocate "
+						"allocated cluster.%s", es);
+				NVolSetErrors(vol);
+			}
+			ntfs_free(rl2);
+			return PTR_ERR(rl);
+		}
+		mftbmp_ni->runlist.rl = rl;
+		status.added_run = 1;
+		ntfs_debug("Adding one run to mft bitmap.");
+		/* Find the last run in the new runlist. */
+		for (; rl[1].length; rl++)
+			;
+	}
+	/*
+	 * Update the attribute record as well.  Note: @rl is the last
+	 * (non-terminator) runlist element of mft bitmap.
+	 */
+	mrec = map_mft_record(mft_ni);
+	if (IS_ERR(mrec)) {
+		ntfs_error(vol->sb, "Failed to map mft record.");
+		ret = PTR_ERR(mrec);
+		goto undo_alloc;
+	}
+	ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
+	if (unlikely(!ctx)) {
+		ntfs_error(vol->sb, "Failed to get search context.");
+		ret = -ENOMEM;
+		goto undo_alloc;
+	}
+	ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
+			mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
+			0, ctx);
+	if (unlikely(ret)) {
+		ntfs_error(vol->sb, "Failed to find last attribute extent of "
+				"mft bitmap attribute.");
+		if (ret == -ENOENT)
+			ret = -EIO;
+		goto undo_alloc;
+	}
+	a = ctx->attr;
+	ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
+	/* Search back for the previous last allocated cluster of mft bitmap. */
+	for (rl2 = rl; rl2 > mftbmp_ni->runlist.rl; rl2--) {
+		if (ll >= rl2->vcn)
+			break;
+	}
+	BUG_ON(ll < rl2->vcn);
+	BUG_ON(ll >= rl2->vcn + rl2->length);
+	/* Get the size for the new mapping pairs array for this extent. */
+	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
+	if (unlikely(mp_size <= 0)) {
+		ntfs_error(vol->sb, "Get size for mapping pairs failed for "
+				"mft bitmap attribute extent.");
+		ret = mp_size;
+		if (!ret)
+			ret = -EIO;
+		goto undo_alloc;
+	}
+	/* Expand the attribute record if necessary. */
+	old_alen = le32_to_cpu(a->length);
+	ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
+			le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
+	if (unlikely(ret)) {
+		if (ret != -ENOSPC) {
+			ntfs_error(vol->sb, "Failed to resize attribute "
+					"record for mft bitmap attribute.");
+			goto undo_alloc;
+		}
+		// TODO: Deal with this by moving this extent to a new mft
+		// record or by starting a new extent in a new mft record or by
+		// moving other attributes out of this mft record.
+		// Note: It will need to be a special mft record and if none of
+		// those are available it gets rather complicated...
+		ntfs_error(vol->sb, "Not enough space in this mft record to "
+				"accommodate extended mft bitmap attribute "
+				"extent.  Cannot handle this yet.");
+		ret = -EOPNOTSUPP;
+		goto undo_alloc;
+	}
+	status.mp_rebuilt = 1;
+	/* Generate the mapping pairs array directly into the attr record. */
+	ret = ntfs_mapping_pairs_build(vol, (u8*)a +
+			le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
+			mp_size, rl2, ll, -1, NULL);
+	if (unlikely(ret)) {
+		ntfs_error(vol->sb, "Failed to build mapping pairs array for "
+				"mft bitmap attribute.");
+		goto undo_alloc;
+	}
+	/* Update the highest_vcn. */
+	a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
+	/*
+	 * We now have extended the mft bitmap allocated_size by one cluster.
+	 * Reflect this in the ntfs_inode structure and the attribute record.
+	 */
+	if (a->data.non_resident.lowest_vcn) {
+		/*
+		 * We are not in the first attribute extent, switch to it, but
+		 * first ensure the changes will make it to disk later.
+		 */
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+		ntfs_attr_reinit_search_ctx(ctx);
+		ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
+				mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL,
+				0, ctx);
+		if (unlikely(ret)) {
+			ntfs_error(vol->sb, "Failed to find first attribute "
+					"extent of mft bitmap attribute.");
+			goto restore_undo_alloc;
+		}
+		a = ctx->attr;
+	}
+	write_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	mftbmp_ni->allocated_size += vol->cluster_size;
+	a->data.non_resident.allocated_size =
+			cpu_to_sle64(mftbmp_ni->allocated_size);
+	write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	/* Ensure the changes make it to disk. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(mft_ni);
+	up_write(&mftbmp_ni->runlist.lock);
+	ntfs_debug("Done.");
+	return 0;
+restore_undo_alloc:
+	ntfs_attr_reinit_search_ctx(ctx);
+	if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
+			mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
+			0, ctx)) {
+		ntfs_error(vol->sb, "Failed to find last attribute extent of "
+				"mft bitmap attribute.%s", es);
+		write_lock_irqsave(&mftbmp_ni->size_lock, flags);
+		mftbmp_ni->allocated_size += vol->cluster_size;
+		write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+		ntfs_attr_put_search_ctx(ctx);
+		unmap_mft_record(mft_ni);
+		up_write(&mftbmp_ni->runlist.lock);
+		/*
+		 * The only thing that is now wrong is ->allocated_size of the
+		 * base attribute extent which chkdsk should be able to fix.
+		 */
+		NVolSetErrors(vol);
+		return ret;
+	}
+	a = ctx->attr;
+	a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 2);
+undo_alloc:
+	if (status.added_cluster) {
+		/* Truncate the last run in the runlist by one cluster. */
+		rl->length--;
+		rl[1].vcn--;
+	} else if (status.added_run) {
+		lcn = rl->lcn;
+		/* Remove the last run from the runlist. */
+		rl->lcn = rl[1].lcn;
+		rl->length = 0;
+	}
+	/* Deallocate the cluster. */
+	down_write(&vol->lcnbmp_lock);
+	if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
+		ntfs_error(vol->sb, "Failed to free allocated cluster.%s", es);
+		NVolSetErrors(vol);
+	}
+	up_write(&vol->lcnbmp_lock);
+	if (status.mp_rebuilt) {
+		if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset),
+				old_alen - le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset),
+				rl2, ll, -1, NULL)) {
+			ntfs_error(vol->sb, "Failed to restore mapping pairs "
+					"array.%s", es);
+			NVolSetErrors(vol);
+		}
+		if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
+			ntfs_error(vol->sb, "Failed to restore attribute "
+					"record.%s", es);
+			NVolSetErrors(vol);
+		}
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+	}
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (!IS_ERR(mrec))
+		unmap_mft_record(mft_ni);
+	up_write(&mftbmp_ni->runlist.lock);
+	return ret;
+}
+
+/**
+ * ntfs_mft_bitmap_extend_initialized_nolock - extend mftbmp initialized data
+ * @vol:	volume on which to extend the mft bitmap attribute
+ *
+ * Extend the initialized portion of the mft bitmap attribute on the ntfs
+ * volume @vol by 8 bytes.
+ *
+ * Note:  Only changes initialized_size and data_size, i.e. requires that
+ * allocated_size is big enough to fit the new initialized_size.
+ *
+ * Return 0 on success and -error on error.
+ *
+ * Locking: Caller must hold vol->mftbmp_lock for writing.
+ */
+static int ntfs_mft_bitmap_extend_initialized_nolock(ntfs_volume *vol)
+{
+	s64 old_data_size, old_initialized_size;
+	unsigned long flags;
+	struct inode *mftbmp_vi;
+	ntfs_inode *mft_ni, *mftbmp_ni;
+	ntfs_attr_search_ctx *ctx;
+	MFT_RECORD *mrec;
+	ATTR_RECORD *a;
+	int ret;
+
+	ntfs_debug("Extending mft bitmap initiailized (and data) size.");
+	mft_ni = NTFS_I(vol->mft_ino);
+	mftbmp_vi = vol->mftbmp_ino;
+	mftbmp_ni = NTFS_I(mftbmp_vi);
+	/* Get the attribute record. */
+	mrec = map_mft_record(mft_ni);
+	if (IS_ERR(mrec)) {
+		ntfs_error(vol->sb, "Failed to map mft record.");
+		return PTR_ERR(mrec);
+	}
+	ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
+	if (unlikely(!ctx)) {
+		ntfs_error(vol->sb, "Failed to get search context.");
+		ret = -ENOMEM;
+		goto unm_err_out;
+	}
+	ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
+			mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(ret)) {
+		ntfs_error(vol->sb, "Failed to find first attribute extent of "
+				"mft bitmap attribute.");
+		if (ret == -ENOENT)
+			ret = -EIO;
+		goto put_err_out;
+	}
+	a = ctx->attr;
+	write_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	old_data_size = i_size_read(mftbmp_vi);
+	old_initialized_size = mftbmp_ni->initialized_size;
+	/*
+	 * We can simply update the initialized_size before filling the space
+	 * with zeroes because the caller is holding the mft bitmap lock for
+	 * writing which ensures that no one else is trying to access the data.
+	 */
+	mftbmp_ni->initialized_size += 8;
+	a->data.non_resident.initialized_size =
+			cpu_to_sle64(mftbmp_ni->initialized_size);
+	if (mftbmp_ni->initialized_size > old_data_size) {
+		i_size_write(mftbmp_vi, mftbmp_ni->initialized_size);
+		a->data.non_resident.data_size =
+				cpu_to_sle64(mftbmp_ni->initialized_size);
+	}
+	write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	/* Ensure the changes make it to disk. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(mft_ni);
+	/* Initialize the mft bitmap attribute value with zeroes. */
+	ret = ntfs_attr_set(mftbmp_ni, old_initialized_size, 8, 0);
+	if (likely(!ret)) {
+		ntfs_debug("Done.  (Wrote eight initialized bytes to mft "
+				"bitmap.");
+		return 0;
+	}
+	ntfs_error(vol->sb, "Failed to write to mft bitmap.");
+	/* Try to recover from the error. */
+	mrec = map_mft_record(mft_ni);
+	if (IS_ERR(mrec)) {
+		ntfs_error(vol->sb, "Failed to map mft record.%s", es);
+		NVolSetErrors(vol);
+		return ret;
+	}
+	ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
+	if (unlikely(!ctx)) {
+		ntfs_error(vol->sb, "Failed to get search context.%s", es);
+		NVolSetErrors(vol);
+		goto unm_err_out;
+	}
+	if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
+			mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx)) {
+		ntfs_error(vol->sb, "Failed to find first attribute extent of "
+				"mft bitmap attribute.%s", es);
+		NVolSetErrors(vol);
+put_err_out:
+		ntfs_attr_put_search_ctx(ctx);
+unm_err_out:
+		unmap_mft_record(mft_ni);
+		goto err_out;
+	}
+	a = ctx->attr;
+	write_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	mftbmp_ni->initialized_size = old_initialized_size;
+	a->data.non_resident.initialized_size =
+			cpu_to_sle64(old_initialized_size);
+	if (i_size_read(mftbmp_vi) != old_data_size) {
+		i_size_write(mftbmp_vi, old_data_size);
+		a->data.non_resident.data_size = cpu_to_sle64(old_data_size);
+	}
+	write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(mft_ni);
+#ifdef DEBUG
+	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	ntfs_debug("Restored status of mftbmp: allocated_size 0x%llx, "
+			"data_size 0x%llx, initialized_size 0x%llx.",
+			(long long)mftbmp_ni->allocated_size,
+			(long long)i_size_read(mftbmp_vi),
+			(long long)mftbmp_ni->initialized_size);
+	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+#endif /* DEBUG */
+err_out:
+	return ret;
+}
+
+/**
+ * ntfs_mft_data_extend_allocation_nolock - extend mft data attribute
+ * @vol:	volume on which to extend the mft data attribute
+ *
+ * Extend the mft data attribute on the ntfs volume @vol by 16 mft records
+ * worth of clusters or if not enough space for this by one mft record worth
+ * of clusters.
+ *
+ * Note:  Only changes allocated_size, i.e. does not touch initialized_size or
+ * data_size.
+ *
+ * Return 0 on success and -errno on error.
+ *
+ * Locking: - Caller must hold vol->mftbmp_lock for writing.
+ *	    - This function takes NTFS_I(vol->mft_ino)->runlist.lock for
+ *	      writing and releases it before returning.
+ *	    - This function calls functions which take vol->lcnbmp_lock for
+ *	      writing and release it before returning.
+ */
+static int ntfs_mft_data_extend_allocation_nolock(ntfs_volume *vol)
+{
+	LCN lcn;
+	VCN old_last_vcn;
+	s64 min_nr, nr, ll;
+	unsigned long flags;
+	ntfs_inode *mft_ni;
+	runlist_element *rl, *rl2;
+	ntfs_attr_search_ctx *ctx = NULL;
+	MFT_RECORD *mrec;
+	ATTR_RECORD *a = NULL;
+	int ret, mp_size;
+	u32 old_alen = 0;
+	bool mp_rebuilt = false;
+
+	ntfs_debug("Extending mft data allocation.");
+	mft_ni = NTFS_I(vol->mft_ino);
+	/*
+	 * Determine the preferred allocation location, i.e. the last lcn of
+	 * the mft data attribute.  The allocated size of the mft data
+	 * attribute cannot be zero so we are ok to do this.
+	 */
+	down_write(&mft_ni->runlist.lock);
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	ll = mft_ni->allocated_size;
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	rl = ntfs_attr_find_vcn_nolock(mft_ni,
+			(ll - 1) >> vol->cluster_size_bits, NULL);
+	if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
+		up_write(&mft_ni->runlist.lock);
+		ntfs_error(vol->sb, "Failed to determine last allocated "
+				"cluster of mft data attribute.");
+		if (!IS_ERR(rl))
+			ret = -EIO;
+		else
+			ret = PTR_ERR(rl);
+		return ret;
+	}
+	lcn = rl->lcn + rl->length;
+	ntfs_debug("Last lcn of mft data attribute is 0x%llx.", (long long)lcn);
+	/* Minimum allocation is one mft record worth of clusters. */
+	min_nr = vol->mft_record_size >> vol->cluster_size_bits;
+	if (!min_nr)
+		min_nr = 1;
+	/* Want to allocate 16 mft records worth of clusters. */
+	nr = vol->mft_record_size << 4 >> vol->cluster_size_bits;
+	if (!nr)
+		nr = min_nr;
+	/* Ensure we do not go above 2^32-1 mft records. */
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	ll = mft_ni->allocated_size;
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
+			vol->mft_record_size_bits >= (1ll << 32))) {
+		nr = min_nr;
+		if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
+				vol->mft_record_size_bits >= (1ll << 32))) {
+			ntfs_warning(vol->sb, "Cannot allocate mft record "
+					"because the maximum number of inodes "
+					"(2^32) has already been reached.");
+			up_write(&mft_ni->runlist.lock);
+			return -ENOSPC;
+		}
+	}
+	ntfs_debug("Trying mft data allocation with %s cluster count %lli.",
+			nr > min_nr ? "default" : "minimal", (long long)nr);
+	old_last_vcn = rl[1].vcn;
+	do {
+		rl2 = ntfs_cluster_alloc(vol, old_last_vcn, nr, lcn, MFT_ZONE,
+				true);
+		if (likely(!IS_ERR(rl2)))
+			break;
+		if (PTR_ERR(rl2) != -ENOSPC || nr == min_nr) {
+			ntfs_error(vol->sb, "Failed to allocate the minimal "
+					"number of clusters (%lli) for the "
+					"mft data attribute.", (long long)nr);
+			up_write(&mft_ni->runlist.lock);
+			return PTR_ERR(rl2);
+		}
+		/*
+		 * There is not enough space to do the allocation, but there
+		 * might be enough space to do a minimal allocation so try that
+		 * before failing.
+		 */
+		nr = min_nr;
+		ntfs_debug("Retrying mft data allocation with minimal cluster "
+				"count %lli.", (long long)nr);
+	} while (1);
+	rl = ntfs_runlists_merge(mft_ni->runlist.rl, rl2);
+	if (IS_ERR(rl)) {
+		up_write(&mft_ni->runlist.lock);
+		ntfs_error(vol->sb, "Failed to merge runlists for mft data "
+				"attribute.");
+		if (ntfs_cluster_free_from_rl(vol, rl2)) {
+			ntfs_error(vol->sb, "Failed to deallocate clusters "
+					"from the mft data attribute.%s", es);
+			NVolSetErrors(vol);
+		}
+		ntfs_free(rl2);
+		return PTR_ERR(rl);
+	}
+	mft_ni->runlist.rl = rl;
+	ntfs_debug("Allocated %lli clusters.", (long long)nr);
+	/* Find the last run in the new runlist. */
+	for (; rl[1].length; rl++)
+		;
+	/* Update the attribute record as well. */
+	mrec = map_mft_record(mft_ni);
+	if (IS_ERR(mrec)) {
+		ntfs_error(vol->sb, "Failed to map mft record.");
+		ret = PTR_ERR(mrec);
+		goto undo_alloc;
+	}
+	ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
+	if (unlikely(!ctx)) {
+		ntfs_error(vol->sb, "Failed to get search context.");
+		ret = -ENOMEM;
+		goto undo_alloc;
+	}
+	ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
+			CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx);
+	if (unlikely(ret)) {
+		ntfs_error(vol->sb, "Failed to find last attribute extent of "
+				"mft data attribute.");
+		if (ret == -ENOENT)
+			ret = -EIO;
+		goto undo_alloc;
+	}
+	a = ctx->attr;
+	ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
+	/* Search back for the previous last allocated cluster of mft bitmap. */
+	for (rl2 = rl; rl2 > mft_ni->runlist.rl; rl2--) {
+		if (ll >= rl2->vcn)
+			break;
+	}
+	BUG_ON(ll < rl2->vcn);
+	BUG_ON(ll >= rl2->vcn + rl2->length);
+	/* Get the size for the new mapping pairs array for this extent. */
+	mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
+	if (unlikely(mp_size <= 0)) {
+		ntfs_error(vol->sb, "Get size for mapping pairs failed for "
+				"mft data attribute extent.");
+		ret = mp_size;
+		if (!ret)
+			ret = -EIO;
+		goto undo_alloc;
+	}
+	/* Expand the attribute record if necessary. */
+	old_alen = le32_to_cpu(a->length);
+	ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
+			le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
+	if (unlikely(ret)) {
+		if (ret != -ENOSPC) {
+			ntfs_error(vol->sb, "Failed to resize attribute "
+					"record for mft data attribute.");
+			goto undo_alloc;
+		}
+		// TODO: Deal with this by moving this extent to a new mft
+		// record or by starting a new extent in a new mft record or by
+		// moving other attributes out of this mft record.
+		// Note: Use the special reserved mft records and ensure that
+		// this extent is not required to find the mft record in
+		// question.  If no free special records left we would need to
+		// move an existing record away, insert ours in its place, and
+		// then place the moved record into the newly allocated space
+		// and we would then need to update all references to this mft
+		// record appropriately.  This is rather complicated...
+		ntfs_error(vol->sb, "Not enough space in this mft record to "
+				"accommodate extended mft data attribute "
+				"extent.  Cannot handle this yet.");
+		ret = -EOPNOTSUPP;
+		goto undo_alloc;
+	}
+	mp_rebuilt = true;
+	/* Generate the mapping pairs array directly into the attr record. */
+	ret = ntfs_mapping_pairs_build(vol, (u8*)a +
+			le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
+			mp_size, rl2, ll, -1, NULL);
+	if (unlikely(ret)) {
+		ntfs_error(vol->sb, "Failed to build mapping pairs array of "
+				"mft data attribute.");
+		goto undo_alloc;
+	}
+	/* Update the highest_vcn. */
+	a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
+	/*
+	 * We now have extended the mft data allocated_size by nr clusters.
+	 * Reflect this in the ntfs_inode structure and the attribute record.
+	 * @rl is the last (non-terminator) runlist element of mft data
+	 * attribute.
+	 */
+	if (a->data.non_resident.lowest_vcn) {
+		/*
+		 * We are not in the first attribute extent, switch to it, but
+		 * first ensure the changes will make it to disk later.
+		 */
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+		ntfs_attr_reinit_search_ctx(ctx);
+		ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name,
+				mft_ni->name_len, CASE_SENSITIVE, 0, NULL, 0,
+				ctx);
+		if (unlikely(ret)) {
+			ntfs_error(vol->sb, "Failed to find first attribute "
+					"extent of mft data attribute.");
+			goto restore_undo_alloc;
+		}
+		a = ctx->attr;
+	}
+	write_lock_irqsave(&mft_ni->size_lock, flags);
+	mft_ni->allocated_size += nr << vol->cluster_size_bits;
+	a->data.non_resident.allocated_size =
+			cpu_to_sle64(mft_ni->allocated_size);
+	write_unlock_irqrestore(&mft_ni->size_lock, flags);
+	/* Ensure the changes make it to disk. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(mft_ni);
+	up_write(&mft_ni->runlist.lock);
+	ntfs_debug("Done.");
+	return 0;
+restore_undo_alloc:
+	ntfs_attr_reinit_search_ctx(ctx);
+	if (ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
+			CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx)) {
+		ntfs_error(vol->sb, "Failed to find last attribute extent of "
+				"mft data attribute.%s", es);
+		write_lock_irqsave(&mft_ni->size_lock, flags);
+		mft_ni->allocated_size += nr << vol->cluster_size_bits;
+		write_unlock_irqrestore(&mft_ni->size_lock, flags);
+		ntfs_attr_put_search_ctx(ctx);
+		unmap_mft_record(mft_ni);
+		up_write(&mft_ni->runlist.lock);
+		/*
+		 * The only thing that is now wrong is ->allocated_size of the
+		 * base attribute extent which chkdsk should be able to fix.
+		 */
+		NVolSetErrors(vol);
+		return ret;
+	}
+	ctx->attr->data.non_resident.highest_vcn =
+			cpu_to_sle64(old_last_vcn - 1);
+undo_alloc:
+	if (ntfs_cluster_free(mft_ni, old_last_vcn, -1, ctx) < 0) {
+		ntfs_error(vol->sb, "Failed to free clusters from mft data "
+				"attribute.%s", es);
+		NVolSetErrors(vol);
+	}
+	a = ctx->attr;
+	if (ntfs_rl_truncate_nolock(vol, &mft_ni->runlist, old_last_vcn)) {
+		ntfs_error(vol->sb, "Failed to truncate mft data attribute "
+				"runlist.%s", es);
+		NVolSetErrors(vol);
+	}
+	if (mp_rebuilt && !IS_ERR(ctx->mrec)) {
+		if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset),
+				old_alen - le16_to_cpu(
+				a->data.non_resident.mapping_pairs_offset),
+				rl2, ll, -1, NULL)) {
+			ntfs_error(vol->sb, "Failed to restore mapping pairs "
+					"array.%s", es);
+			NVolSetErrors(vol);
+		}
+		if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
+			ntfs_error(vol->sb, "Failed to restore attribute "
+					"record.%s", es);
+			NVolSetErrors(vol);
+		}
+		flush_dcache_mft_record_page(ctx->ntfs_ino);
+		mark_mft_record_dirty(ctx->ntfs_ino);
+	} else if (IS_ERR(ctx->mrec)) {
+		ntfs_error(vol->sb, "Failed to restore attribute search "
+				"context.%s", es);
+		NVolSetErrors(vol);
+	}
+	if (ctx)
+		ntfs_attr_put_search_ctx(ctx);
+	if (!IS_ERR(mrec))
+		unmap_mft_record(mft_ni);
+	up_write(&mft_ni->runlist.lock);
+	return ret;
+}
+
+/**
+ * ntfs_mft_record_layout - layout an mft record into a memory buffer
+ * @vol:	volume to which the mft record will belong
+ * @mft_no:	mft reference specifying the mft record number
+ * @m:		destination buffer of size >= @vol->mft_record_size bytes
+ *
+ * Layout an empty, unused mft record with the mft record number @mft_no into
+ * the buffer @m.  The volume @vol is needed because the mft record structure
+ * was modified in NTFS 3.1 so we need to know which volume version this mft
+ * record will be used on.
+ *
+ * Return 0 on success and -errno on error.
+ */
+static int ntfs_mft_record_layout(const ntfs_volume *vol, const s64 mft_no,
+		MFT_RECORD *m)
+{
+	ATTR_RECORD *a;
+
+	ntfs_debug("Entering for mft record 0x%llx.", (long long)mft_no);
+	if (mft_no >= (1ll << 32)) {
+		ntfs_error(vol->sb, "Mft record number 0x%llx exceeds "
+				"maximum of 2^32.", (long long)mft_no);
+		return -ERANGE;
+	}
+	/* Start by clearing the whole mft record to gives us a clean slate. */
+	memset(m, 0, vol->mft_record_size);
+	/* Aligned to 2-byte boundary. */
+	if (vol->major_ver < 3 || (vol->major_ver == 3 && !vol->minor_ver))
+		m->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD_OLD) + 1) & ~1);
+	else {
+		m->usa_ofs = cpu_to_le16((sizeof(MFT_RECORD) + 1) & ~1);
+		/*
+		 * Set the NTFS 3.1+ specific fields while we know that the
+		 * volume version is 3.1+.
+		 */
+		m->reserved = 0;
+		m->mft_record_number = cpu_to_le32((u32)mft_no);
+	}
+	m->magic = magic_FILE;
+	if (vol->mft_record_size >= NTFS_BLOCK_SIZE)
+		m->usa_count = cpu_to_le16(vol->mft_record_size /
+				NTFS_BLOCK_SIZE + 1);
+	else {
+		m->usa_count = cpu_to_le16(1);
+		ntfs_warning(vol->sb, "Sector size is bigger than mft record "
+				"size.  Setting usa_count to 1.  If chkdsk "
+				"reports this as corruption, please email "
+				"linux-ntfs-dev@lists.sourceforge.net stating "
+				"that you saw this message and that the "
+				"modified filesystem created was corrupt.  "
+				"Thank you.");
+	}
+	/* Set the update sequence number to 1. */
+	*(le16*)((u8*)m + le16_to_cpu(m->usa_ofs)) = cpu_to_le16(1);
+	m->lsn = 0;
+	m->sequence_number = cpu_to_le16(1);
+	m->link_count = 0;
+	/*
+	 * Place the attributes straight after the update sequence array,
+	 * aligned to 8-byte boundary.
+	 */
+	m->attrs_offset = cpu_to_le16((le16_to_cpu(m->usa_ofs) +
+			(le16_to_cpu(m->usa_count) << 1) + 7) & ~7);
+	m->flags = 0;
+	/*
+	 * Using attrs_offset plus eight bytes (for the termination attribute).
+	 * attrs_offset is already aligned to 8-byte boundary, so no need to
+	 * align again.
+	 */
+	m->bytes_in_use = cpu_to_le32(le16_to_cpu(m->attrs_offset) + 8);
+	m->bytes_allocated = cpu_to_le32(vol->mft_record_size);
+	m->base_mft_record = 0;
+	m->next_attr_instance = 0;
+	/* Add the termination attribute. */
+	a = (ATTR_RECORD*)((u8*)m + le16_to_cpu(m->attrs_offset));
+	a->type = AT_END;
+	a->length = 0;
+	ntfs_debug("Done.");
+	return 0;
+}
+
+/**
+ * ntfs_mft_record_format - format an mft record on an ntfs volume
+ * @vol:	volume on which to format the mft record
+ * @mft_no:	mft record number to format
+ *
+ * Format the mft record @mft_no in $MFT/$DATA, i.e. lay out an empty, unused
+ * mft record into the appropriate place of the mft data attribute.  This is
+ * used when extending the mft data attribute.
+ *
+ * Return 0 on success and -errno on error.
+ */
+static int ntfs_mft_record_format(const ntfs_volume *vol, const s64 mft_no)
+{
+	loff_t i_size;
+	struct inode *mft_vi = vol->mft_ino;
+	struct page *page;
+	MFT_RECORD *m;
+	pgoff_t index, end_index;
+	unsigned int ofs;
+	int err;
+
+	ntfs_debug("Entering for mft record 0x%llx.", (long long)mft_no);
+	/*
+	 * The index into the page cache and the offset within the page cache
+	 * page of the wanted mft record.
+	 */
+	index = mft_no << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
+	ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
+	/* The maximum valid index into the page cache for $MFT's data. */
+	i_size = i_size_read(mft_vi);
+	end_index = i_size >> PAGE_CACHE_SHIFT;
+	if (unlikely(index >= end_index)) {
+		if (unlikely(index > end_index || ofs + vol->mft_record_size >=
+				(i_size & ~PAGE_CACHE_MASK))) {
+			ntfs_error(vol->sb, "Tried to format non-existing mft "
+					"record 0x%llx.", (long long)mft_no);
+			return -ENOENT;
+		}
+	}
+	/* Read, map, and pin the page containing the mft record. */
+	page = ntfs_map_page(mft_vi->i_mapping, index);
+	if (IS_ERR(page)) {
+		ntfs_error(vol->sb, "Failed to map page containing mft record "
+				"to format 0x%llx.", (long long)mft_no);
+		return PTR_ERR(page);
+	}
+	lock_page(page);
+	BUG_ON(!PageUptodate(page));
+	ClearPageUptodate(page);
+	m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
+	err = ntfs_mft_record_layout(vol, mft_no, m);
+	if (unlikely(err)) {
+		ntfs_error(vol->sb, "Failed to layout mft record 0x%llx.",
+				(long long)mft_no);
+		SetPageUptodate(page);
+		unlock_page(page);
+		ntfs_unmap_page(page);
+		return err;
+	}
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	unlock_page(page);
+	/*
+	 * Make sure the mft record is written out to disk.  We could use
+	 * ilookup5() to check if an inode is in icache and so on but this is
+	 * unnecessary as ntfs_writepage() will write the dirty record anyway.
+	 */
+	mark_ntfs_record_dirty(page, ofs);
+	ntfs_unmap_page(page);
+	ntfs_debug("Done.");
+	return 0;
+}
+
+/**
+ * ntfs_mft_record_alloc - allocate an mft record on an ntfs volume
+ * @vol:	[IN]  volume on which to allocate the mft record
+ * @mode:	[IN]  mode if want a file or directory, i.e. base inode or 0
+ * @base_ni:	[IN]  open base inode if allocating an extent mft record or NULL
+ * @mrec:	[OUT] on successful return this is the mapped mft record
+ *
+ * Allocate an mft record in $MFT/$DATA of an open ntfs volume @vol.
+ *
+ * If @base_ni is NULL make the mft record a base mft record, i.e. a file or
+ * direvctory inode, and allocate it at the default allocator position.  In
+ * this case @mode is the file mode as given to us by the caller.  We in
+ * particular use @mode to distinguish whether a file or a directory is being
+ * created (S_IFDIR(mode) and S_IFREG(mode), respectively).
+ *
+ * If @base_ni is not NULL make the allocated mft record an extent record,
+ * allocate it starting at the mft record after the base mft record and attach
+ * the allocated and opened ntfs inode to the base inode @base_ni.  In this
+ * case @mode must be 0 as it is meaningless for extent inodes.
+ *
+ * You need to check the return value with IS_ERR().  If false, the function
+ * was successful and the return value is the now opened ntfs inode of the
+ * allocated mft record.  *@mrec is then set to the allocated, mapped, pinned,
+ * and locked mft record.  If IS_ERR() is true, the function failed and the
+ * error code is obtained from PTR_ERR(return value).  *@mrec is undefined in
+ * this case.
+ *
+ * Allocation strategy:
+ *
+ * To find a free mft record, we scan the mft bitmap for a zero bit.  To
+ * optimize this we start scanning at the place specified by @base_ni or if
+ * @base_ni is NULL we start where we last stopped and we perform wrap around
+ * when we reach the end.  Note, we do not try to allocate mft records below
+ * number 24 because numbers 0 to 15 are the defined system files anyway and 16
+ * to 24 are special in that they are used for storing extension mft records
+ * for the $DATA attribute of $MFT.  This is required to avoid the possibility
+ * of creating a runlist with a circular dependency which once written to disk
+ * can never be read in again.  Windows will only use records 16 to 24 for
+ * normal files if the volume is completely out of space.  We never use them
+ * which means that when the volume is really out of space we cannot create any
+ * more files while Windows can still create up to 8 small files.  We can start
+ * doing this at some later time, it does not matter much for now.
+ *
+ * When scanning the mft bitmap, we only search up to the last allocated mft
+ * record.  If there are no free records left in the range 24 to number of
+ * allocated mft records, then we extend the $MFT/$DATA attribute in order to
+ * create free mft records.  We extend the allocated size of $MFT/$DATA by 16
+ * records at a time or one cluster, if cluster size is above 16kiB.  If there
+ * is not sufficient space to do this, we try to extend by a single mft record
+ * or one cluster, if cluster size is above the mft record size.
+ *
+ * No matter how many mft records we allocate, we initialize only the first
+ * allocated mft record, incrementing mft data size and initialized size
+ * accordingly, open an ntfs_inode for it and return it to the caller, unless
+ * there are less than 24 mft records, in which case we allocate and initialize
+ * mft records until we reach record 24 which we consider as the first free mft
+ * record for use by normal files.
+ *
+ * If during any stage we overflow the initialized data in the mft bitmap, we
+ * extend the initialized size (and data size) by 8 bytes, allocating another
+ * cluster if required.  The bitmap data size has to be at least equal to the
+ * number of mft records in the mft, but it can be bigger, in which case the
+ * superflous bits are padded with zeroes.
+ *
+ * Thus, when we return successfully (IS_ERR() is false), we will have:
+ *	- initialized / extended the mft bitmap if necessary,
+ *	- initialized / extended the mft data if necessary,
+ *	- set the bit corresponding to the mft record being allocated in the
+ *	  mft bitmap,
+ *	- opened an ntfs_inode for the allocated mft record, and we will have
+ *	- returned the ntfs_inode as well as the allocated mapped, pinned, and
+ *	  locked mft record.
+ *
+ * On error, the volume will be left in a consistent state and no record will
+ * be allocated.  If rolling back a partial operation fails, we may leave some
+ * inconsistent metadata in which case we set NVolErrors() so the volume is
+ * left dirty when unmounted.
+ *
+ * Note, this function cannot make use of most of the normal functions, like
+ * for example for attribute resizing, etc, because when the run list overflows
+ * the base mft record and an attribute list is used, it is very important that
+ * the extension mft records used to store the $DATA attribute of $MFT can be
+ * reached without having to read the information contained inside them, as
+ * this would make it impossible to find them in the first place after the
+ * volume is unmounted.  $MFT/$BITMAP probably does not need to follow this
+ * rule because the bitmap is not essential for finding the mft records, but on
+ * the other hand, handling the bitmap in this special way would make life
+ * easier because otherwise there might be circular invocations of functions
+ * when reading the bitmap.
+ */
+ntfs_inode *ntfs_mft_record_alloc(ntfs_volume *vol, const int mode,
+		ntfs_inode *base_ni, MFT_RECORD **mrec)
+{
+	s64 ll, bit, old_data_initialized, old_data_size;
+	unsigned long flags;
+	struct inode *vi;
+	struct page *page;
+	ntfs_inode *mft_ni, *mftbmp_ni, *ni;
+	ntfs_attr_search_ctx *ctx;
+	MFT_RECORD *m;
+	ATTR_RECORD *a;
+	pgoff_t index;
+	unsigned int ofs;
+	int err;
+	le16 seq_no, usn;
+	bool record_formatted = false;
+
+	if (base_ni) {
+		ntfs_debug("Entering (allocating an extent mft record for "
+				"base mft record 0x%llx).",
+				(long long)base_ni->mft_no);
+		/* @mode and @base_ni are mutually exclusive. */
+		BUG_ON(mode);
+	} else
+		ntfs_debug("Entering (allocating a base mft record).");
+	if (mode) {
+		/* @mode and @base_ni are mutually exclusive. */
+		BUG_ON(base_ni);
+		/* We only support creation of normal files and directories. */
+		if (!S_ISREG(mode) && !S_ISDIR(mode))
+			return ERR_PTR(-EOPNOTSUPP);
+	}
+	BUG_ON(!mrec);
+	mft_ni = NTFS_I(vol->mft_ino);
+	mftbmp_ni = NTFS_I(vol->mftbmp_ino);
+	down_write(&vol->mftbmp_lock);
+	bit = ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(vol, base_ni);
+	if (bit >= 0) {
+		ntfs_debug("Found and allocated free record (#1), bit 0x%llx.",
+				(long long)bit);
+		goto have_alloc_rec;
+	}
+	if (bit != -ENOSPC) {
+		up_write(&vol->mftbmp_lock);
+		return ERR_PTR(bit);
+	}
+	/*
+	 * No free mft records left.  If the mft bitmap already covers more
+	 * than the currently used mft records, the next records are all free,
+	 * so we can simply allocate the first unused mft record.
+	 * Note: We also have to make sure that the mft bitmap at least covers
+	 * the first 24 mft records as they are special and whilst they may not
+	 * be in use, we do not allocate from them.
+	 */
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	ll = mft_ni->initialized_size >> vol->mft_record_size_bits;
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	old_data_initialized = mftbmp_ni->initialized_size;
+	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	if (old_data_initialized << 3 > ll && old_data_initialized > 3) {
+		bit = ll;
+		if (bit < 24)
+			bit = 24;
+		if (unlikely(bit >= (1ll << 32)))
+			goto max_err_out;
+		ntfs_debug("Found free record (#2), bit 0x%llx.",
+				(long long)bit);
+		goto found_free_rec;
+	}
+	/*
+	 * The mft bitmap needs to be expanded until it covers the first unused
+	 * mft record that we can allocate.
+	 * Note: The smallest mft record we allocate is mft record 24.
+	 */
+	bit = old_data_initialized << 3;
+	if (unlikely(bit >= (1ll << 32)))
+		goto max_err_out;
+	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	old_data_size = mftbmp_ni->allocated_size;
+	ntfs_debug("Status of mftbmp before extension: allocated_size 0x%llx, "
+			"data_size 0x%llx, initialized_size 0x%llx.",
+			(long long)old_data_size,
+			(long long)i_size_read(vol->mftbmp_ino),
+			(long long)old_data_initialized);
+	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+	if (old_data_initialized + 8 > old_data_size) {
+		/* Need to extend bitmap by one more cluster. */
+		ntfs_debug("mftbmp: initialized_size + 8 > allocated_size.");
+		err = ntfs_mft_bitmap_extend_allocation_nolock(vol);
+		if (unlikely(err)) {
+			up_write(&vol->mftbmp_lock);
+			goto err_out;
+		}
+#ifdef DEBUG
+		read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+		ntfs_debug("Status of mftbmp after allocation extension: "
+				"allocated_size 0x%llx, data_size 0x%llx, "
+				"initialized_size 0x%llx.",
+				(long long)mftbmp_ni->allocated_size,
+				(long long)i_size_read(vol->mftbmp_ino),
+				(long long)mftbmp_ni->initialized_size);
+		read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+#endif /* DEBUG */
+	}
+	/*
+	 * We now have sufficient allocated space, extend the initialized_size
+	 * as well as the data_size if necessary and fill the new space with
+	 * zeroes.
+	 */
+	err = ntfs_mft_bitmap_extend_initialized_nolock(vol);
+	if (unlikely(err)) {
+		up_write(&vol->mftbmp_lock);
+		goto err_out;
+	}
+#ifdef DEBUG
+	read_lock_irqsave(&mftbmp_ni->size_lock, flags);
+	ntfs_debug("Status of mftbmp after initialized extension: "
+			"allocated_size 0x%llx, data_size 0x%llx, "
+			"initialized_size 0x%llx.",
+			(long long)mftbmp_ni->allocated_size,
+			(long long)i_size_read(vol->mftbmp_ino),
+			(long long)mftbmp_ni->initialized_size);
+	read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
+#endif /* DEBUG */
+	ntfs_debug("Found free record (#3), bit 0x%llx.", (long long)bit);
+found_free_rec:
+	/* @bit is the found free mft record, allocate it in the mft bitmap. */
+	ntfs_debug("At found_free_rec.");
+	err = ntfs_bitmap_set_bit(vol->mftbmp_ino, bit);
+	if (unlikely(err)) {
+		ntfs_error(vol->sb, "Failed to allocate bit in mft bitmap.");
+		up_write(&vol->mftbmp_lock);
+		goto err_out;
+	}
+	ntfs_debug("Set bit 0x%llx in mft bitmap.", (long long)bit);
+have_alloc_rec:
+	/*
+	 * The mft bitmap is now uptodate.  Deal with mft data attribute now.
+	 * Note, we keep hold of the mft bitmap lock for writing until all
+	 * modifications to the mft data attribute are complete, too, as they
+	 * will impact decisions for mft bitmap and mft record allocation done
+	 * by a parallel allocation and if the lock is not maintained a
+	 * parallel allocation could allocate the same mft record as this one.
+	 */
+	ll = (bit + 1) << vol->mft_record_size_bits;
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	old_data_initialized = mft_ni->initialized_size;
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	if (ll <= old_data_initialized) {
+		ntfs_debug("Allocated mft record already initialized.");
+		goto mft_rec_already_initialized;
+	}
+	ntfs_debug("Initializing allocated mft record.");
+	/*
+	 * The mft record is outside the initialized data.  Extend the mft data
+	 * attribute until it covers the allocated record.  The loop is only
+	 * actually traversed more than once when a freshly formatted volume is
+	 * first written to so it optimizes away nicely in the common case.
+	 */
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	ntfs_debug("Status of mft data before extension: "
+			"allocated_size 0x%llx, data_size 0x%llx, "
+			"initialized_size 0x%llx.",
+			(long long)mft_ni->allocated_size,
+			(long long)i_size_read(vol->mft_ino),
+			(long long)mft_ni->initialized_size);
+	while (ll > mft_ni->allocated_size) {
+		read_unlock_irqrestore(&mft_ni->size_lock, flags);
+		err = ntfs_mft_data_extend_allocation_nolock(vol);
+		if (unlikely(err)) {
+			ntfs_error(vol->sb, "Failed to extend mft data "
+					"allocation.");
+			goto undo_mftbmp_alloc_nolock;
+		}
+		read_lock_irqsave(&mft_ni->size_lock, flags);
+		ntfs_debug("Status of mft data after allocation extension: "
+				"allocated_size 0x%llx, data_size 0x%llx, "
+				"initialized_size 0x%llx.",
+				(long long)mft_ni->allocated_size,
+				(long long)i_size_read(vol->mft_ino),
+				(long long)mft_ni->initialized_size);
+	}
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	/*
+	 * Extend mft data initialized size (and data size of course) to reach
+	 * the allocated mft record, formatting the mft records allong the way.
+	 * Note: We only modify the ntfs_inode structure as that is all that is
+	 * needed by ntfs_mft_record_format().  We will update the attribute
+	 * record itself in one fell swoop later on.
+	 */
+	write_lock_irqsave(&mft_ni->size_lock, flags);
+	old_data_initialized = mft_ni->initialized_size;
+	old_data_size = vol->mft_ino->i_size;
+	while (ll > mft_ni->initialized_size) {
+		s64 new_initialized_size, mft_no;
+		
+		new_initialized_size = mft_ni->initialized_size +
+				vol->mft_record_size;
+		mft_no = mft_ni->initialized_size >> vol->mft_record_size_bits;
+		if (new_initialized_size > i_size_read(vol->mft_ino))
+			i_size_write(vol->mft_ino, new_initialized_size);
+		write_unlock_irqrestore(&mft_ni->size_lock, flags);
+		ntfs_debug("Initializing mft record 0x%llx.",
+				(long long)mft_no);
+		err = ntfs_mft_record_format(vol, mft_no);
+		if (unlikely(err)) {
+			ntfs_error(vol->sb, "Failed to format mft record.");
+			goto undo_data_init;
+		}
+		write_lock_irqsave(&mft_ni->size_lock, flags);
+		mft_ni->initialized_size = new_initialized_size;
+	}
+	write_unlock_irqrestore(&mft_ni->size_lock, flags);
+	record_formatted = true;
+	/* Update the mft data attribute record to reflect the new sizes. */
+	m = map_mft_record(mft_ni);
+	if (IS_ERR(m)) {
+		ntfs_error(vol->sb, "Failed to map mft record.");
+		err = PTR_ERR(m);
+		goto undo_data_init;
+	}
+	ctx = ntfs_attr_get_search_ctx(mft_ni, m);
+	if (unlikely(!ctx)) {
+		ntfs_error(vol->sb, "Failed to get search context.");
+		err = -ENOMEM;
+		unmap_mft_record(mft_ni);
+		goto undo_data_init;
+	}
+	err = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
+			CASE_SENSITIVE, 0, NULL, 0, ctx);
+	if (unlikely(err)) {
+		ntfs_error(vol->sb, "Failed to find first attribute extent of "
+				"mft data attribute.");
+		ntfs_attr_put_search_ctx(ctx);
+		unmap_mft_record(mft_ni);
+		goto undo_data_init;
+	}
+	a = ctx->attr;
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	a->data.non_resident.initialized_size =
+			cpu_to_sle64(mft_ni->initialized_size);
+	a->data.non_resident.data_size =
+			cpu_to_sle64(i_size_read(vol->mft_ino));
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+	/* Ensure the changes make it to disk. */
+	flush_dcache_mft_record_page(ctx->ntfs_ino);
+	mark_mft_record_dirty(ctx->ntfs_ino);
+	ntfs_attr_put_search_ctx(ctx);
+	unmap_mft_record(mft_ni);
+	read_lock_irqsave(&mft_ni->size_lock, flags);
+	ntfs_debug("Status of mft data after mft record initialization: "
+			"allocated_size 0x%llx, data_size 0x%llx, "
+			"initialized_size 0x%llx.",
+			(long long)mft_ni->allocated_size,
+			(long long)i_size_read(vol->mft_ino),
+			(long long)mft_ni->initialized_size);
+	BUG_ON(i_size_read(vol->mft_ino) > mft_ni->allocated_size);
+	BUG_ON(mft_ni->initialized_size > i_size_read(vol->mft_ino));
+	read_unlock_irqrestore(&mft_ni->size_lock, flags);
+mft_rec_already_initialized:
+	/*
+	 * We can finally drop the mft bitmap lock as the mft data attribute
+	 * has been fully updated.  The only disparity left is that the
+	 * allocated mft record still needs to be marked as in use to match the
+	 * set bit in the mft bitmap but this is actually not a problem since
+	 * this mft record is not referenced from anywhere yet and the fact
+	 * that it is allocated in the mft bitmap means that no-one will try to
+	 * allocate it either.
+	 */
+	up_write(&vol->mftbmp_lock);
+	/*
+	 * We now have allocated and initialized the mft record.  Calculate the
+	 * index of and the offset within the page cache page the record is in.
+	 */
+	index = bit << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
+	ofs = (bit << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
+	/* Read, map, and pin the page containing the mft record. */
+	page = ntfs_map_page(vol->mft_ino->i_mapping, index);
+	if (IS_ERR(page)) {
+		ntfs_error(vol->sb, "Failed to map page containing allocated "
+				"mft record 0x%llx.", (long long)bit);
+		err = PTR_ERR(page);
+		goto undo_mftbmp_alloc;
+	}
+	lock_page(page);
+	BUG_ON(!PageUptodate(page));
+	ClearPageUptodate(page);
+	m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
+	/* If we just formatted the mft record no need to do it again. */
+	if (!record_formatted) {
+		/* Sanity check that the mft record is really not in use. */
+		if (ntfs_is_file_record(m->magic) &&
+				(m->flags & MFT_RECORD_IN_USE)) {
+			ntfs_error(vol->sb, "Mft record 0x%llx was marked "
+					"free in mft bitmap but is marked "
+					"used itself.  Corrupt filesystem.  "
+					"Unmount and run chkdsk.",
+					(long long)bit);
+			err = -EIO;
+			SetPageUptodate(page);
+			unlock_page(page);
+			ntfs_unmap_page(page);
+			NVolSetErrors(vol);
+			goto undo_mftbmp_alloc;
+		}
+		/*
+		 * We need to (re-)format the mft record, preserving the
+		 * sequence number if it is not zero as well as the update
+		 * sequence number if it is not zero or -1 (0xffff).  This
+		 * means we do not need to care whether or not something went
+		 * wrong with the previous mft record.
+		 */
+		seq_no = m->sequence_number;
+		usn = *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs));
+		err = ntfs_mft_record_layout(vol, bit, m);
+		if (unlikely(err)) {
+			ntfs_error(vol->sb, "Failed to layout allocated mft "
+					"record 0x%llx.", (long long)bit);
+			SetPageUptodate(page);
+			unlock_page(page);
+			ntfs_unmap_page(page);
+			goto undo_mftbmp_alloc;
+		}
+		if (seq_no)
+			m->sequence_number = seq_no;
+		if (usn && le16_to_cpu(usn) != 0xffff)
+			*(le16*)((u8*)m + le16_to_cpu(m->usa_ofs)) = usn;
+	}
+	/* Set the mft record itself in use. */
+	m->flags |= MFT_RECORD_IN_USE;
+	if (S_ISDIR(mode))
+		m->flags |= MFT_RECORD_IS_DIRECTORY;
+	flush_dcache_page(page);
+	SetPageUptodate(page);
+	if (base_ni) {
+		MFT_RECORD *m_tmp;
+
+		/*
+		 * Setup the base mft record in the extent mft record.  This
+		 * completes initialization of the allocated extent mft record
+		 * and we can simply use it with map_extent_mft_record().
+		 */
+		m->base_mft_record = MK_LE_MREF(base_ni->mft_no,
+				base_ni->seq_no);
+		/*
+		 * Allocate an extent inode structure for the new mft record,
+		 * attach it to the base inode @base_ni and map, pin, and lock
+		 * its, i.e. the allocated, mft record.
+		 */
+		m_tmp = map_extent_mft_record(base_ni, bit, &ni);
+		if (IS_ERR(m_tmp)) {
+			ntfs_error(vol->sb, "Failed to map allocated extent "
+					"mft record 0x%llx.", (long long)bit);
+			err = PTR_ERR(m_tmp);
+			/* Set the mft record itself not in use. */
+			m->flags &= cpu_to_le16(
+					~le16_to_cpu(MFT_RECORD_IN_USE));
+			flush_dcache_page(page);
+			/* Make sure the mft record is written out to disk. */
+			mark_ntfs_record_dirty(page, ofs);
+			unlock_page(page);
+			ntfs_unmap_page(page);
+			goto undo_mftbmp_alloc;
+		}
+		BUG_ON(m != m_tmp);
+		/*
+		 * Make sure the allocated mft record is written out to disk.
+		 * No need to set the inode dirty because the caller is going
+		 * to do that anyway after finishing with the new extent mft
+		 * record (e.g. at a minimum a new attribute will be added to
+		 * the mft record.
+		 */
+		mark_ntfs_record_dirty(page, ofs);
+		unlock_page(page);
+		/*
+		 * Need to unmap the page since map_extent_mft_record() mapped
+		 * it as well so we have it mapped twice at the moment.
+		 */
+		ntfs_unmap_page(page);
+	} else {
+		/*
+		 * Allocate a new VFS inode and set it up.  NOTE: @vi->i_nlink
+		 * is set to 1 but the mft record->link_count is 0.  The caller
+		 * needs to bear this in mind.
+		 */
+		vi = new_inode(vol->sb);
+		if (unlikely(!vi)) {
+			err = -ENOMEM;
+			/* Set the mft record itself not in use. */
+			m->flags &= cpu_to_le16(
+					~le16_to_cpu(MFT_RECORD_IN_USE));
+			flush_dcache_page(page);
+			/* Make sure the mft record is written out to disk. */
+			mark_ntfs_record_dirty(page, ofs);
+			unlock_page(page);
+			ntfs_unmap_page(page);
+			goto undo_mftbmp_alloc;
+		}
+		vi->i_ino = bit;
+		/*
+		 * This is for checking whether an inode has changed w.r.t. a
+		 * file so that the file can be updated if necessary (compare
+		 * with f_version).
+		 */
+		vi->i_version = 1;
+
+		/* The owner and group come from the ntfs volume. */
+		vi->i_uid = vol->uid;
+		vi->i_gid = vol->gid;
+
+		/* Initialize the ntfs specific part of @vi. */
+		ntfs_init_big_inode(vi);
+		ni = NTFS_I(vi);
+		/*
+		 * Set the appropriate mode, attribute type, and name.  For
+		 * directories, also setup the index values to the defaults.
+		 */
+		if (S_ISDIR(mode)) {
+			vi->i_mode = S_IFDIR | S_IRWXUGO;
+			vi->i_mode &= ~vol->dmask;
+
+			NInoSetMstProtected(ni);
+			ni->type = AT_INDEX_ALLOCATION;
+			ni->name = I30;
+			ni->name_len = 4;
+
+			ni->itype.index.block_size = 4096;
+			ni->itype.index.block_size_bits = ntfs_ffs(4096) - 1;
+			ni->itype.index.collation_rule = COLLATION_FILE_NAME;
+			if (vol->cluster_size <= ni->itype.index.block_size) {
+				ni->itype.index.vcn_size = vol->cluster_size;
+				ni->itype.index.vcn_size_bits =
+						vol->cluster_size_bits;
+			} else {
+				ni->itype.index.vcn_size = vol->sector_size;
+				ni->itype.index.vcn_size_bits =
+						vol->sector_size_bits;
+			}
+		} else {
+			vi->i_mode = S_IFREG | S_IRWXUGO;
+			vi->i_mode &= ~vol->fmask;
+
+			ni->type = AT_DATA;
+			ni->name = NULL;
+			ni->name_len = 0;
+		}
+		if (IS_RDONLY(vi))
+			vi->i_mode &= ~S_IWUGO;
+
+		/* Set the inode times to the current time. */
+		vi->i_atime = vi->i_mtime = vi->i_ctime =
+			current_fs_time(vi->i_sb);
+		/*
+		 * Set the file size to 0, the ntfs inode sizes are set to 0 by
+		 * the call to ntfs_init_big_inode() below.
+		 */
+		vi->i_size = 0;
+		vi->i_blocks = 0;
+
+		/* Set the sequence number. */
+		vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);
+		/*
+		 * Manually map, pin, and lock the mft record as we already
+		 * have its page mapped and it is very easy to do.
+		 */
+		atomic_inc(&ni->count);
+		mutex_lock(&ni->mrec_lock);
+		ni->page = page;
+		ni->page_ofs = ofs;
+		/*
+		 * Make sure the allocated mft record is written out to disk.
+		 * NOTE: We do not set the ntfs inode dirty because this would
+		 * fail in ntfs_write_inode() because the inode does not have a
+		 * standard information attribute yet.  Also, there is no need
+		 * to set the inode dirty because the caller is going to do
+		 * that anyway after finishing with the new mft record (e.g. at
+		 * a minimum some new attributes will be added to the mft
+		 * record.
+		 */
+		mark_ntfs_record_dirty(page, ofs);
+		unlock_page(page);
+
+		/* Add the inode to the inode hash for the superblock. */
+		insert_inode_hash(vi);
+
+		/* Update the default mft allocation position. */
+		vol->mft_data_pos = bit + 1;
+	}
+	/*
+	 * Return the opened, allocated inode of the allocated mft record as
+	 * well as the mapped, pinned, and locked mft record.
+	 */
+	ntfs_debug("Returning opened, allocated %sinode 0x%llx.",
+			base_ni ? "extent " : "", (long long)bit);
+	*mrec = m;
+	return ni;
+undo_data_init:
+	write_lock_irqsave(&mft_ni->size_lock, flags);
+	mft_ni->initialized_size = old_data_initialized;
+	i_size_write(vol->mft_ino, old_data_size);
+	write_unlock_irqrestore(&mft_ni->size_lock, flags);
+	goto undo_mftbmp_alloc_nolock;
+undo_mftbmp_alloc:
+	down_write(&vol->mftbmp_lock);
+undo_mftbmp_alloc_nolock:
+	if (ntfs_bitmap_clear_bit(vol->mftbmp_ino, bit)) {
+		ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
+		NVolSetErrors(vol);
+	}
+	up_write(&vol->mftbmp_lock);
+err_out:
+	return ERR_PTR(err);
+max_err_out:
+	ntfs_warning(vol->sb, "Cannot allocate mft record because the maximum "
+			"number of inodes (2^32) has already been reached.");
+	up_write(&vol->mftbmp_lock);
+	return ERR_PTR(-ENOSPC);
+}
+
+/**
+ * ntfs_extent_mft_record_free - free an extent mft record on an ntfs volume
+ * @ni:		ntfs inode of the mapped extent mft record to free
+ * @m:		mapped extent mft record of the ntfs inode @ni
+ *
+ * Free the mapped extent mft record @m of the extent ntfs inode @ni.
+ *
+ * Note that this function unmaps the mft record and closes and destroys @ni
+ * internally and hence you cannot use either @ni nor @m any more after this
+ * function returns success.
+ *
+ * On success return 0 and on error return -errno.  @ni and @m are still valid
+ * in this case and have not been freed.
+ *
+ * For some errors an error message is displayed and the success code 0 is
+ * returned and the volume is then left dirty on umount.  This makes sense in
+ * case we could not rollback the changes that were already done since the
+ * caller no longer wants to reference this mft record so it does not matter to
+ * the caller if something is wrong with it as long as it is properly detached
+ * from the base inode.
+ */
+int ntfs_extent_mft_record_free(ntfs_inode *ni, MFT_RECORD *m)
+{
+	unsigned long mft_no = ni->mft_no;
+	ntfs_volume *vol = ni->vol;
+	ntfs_inode *base_ni;
+	ntfs_inode **extent_nis;
+	int i, err;
+	le16 old_seq_no;
+	u16 seq_no;
+	
+	BUG_ON(NInoAttr(ni));
+	BUG_ON(ni->nr_extents != -1);
+
+	mutex_lock(&ni->extent_lock);
+	base_ni = ni->ext.base_ntfs_ino;
+	mutex_unlock(&ni->extent_lock);
+
+	BUG_ON(base_ni->nr_extents <= 0);
+
+	ntfs_debug("Entering for extent inode 0x%lx, base inode 0x%lx.\n",
+			mft_no, base_ni->mft_no);
+
+	mutex_lock(&base_ni->extent_lock);
+
+	/* Make sure we are holding the only reference to the extent inode. */
+	if (atomic_read(&ni->count) > 2) {
+		ntfs_error(vol->sb, "Tried to free busy extent inode 0x%lx, "
+				"not freeing.", base_ni->mft_no);
+		mutex_unlock(&base_ni->extent_lock);
+		return -EBUSY;
+	}
+
+	/* Dissociate the ntfs inode from the base inode. */
+	extent_nis = base_ni->ext.extent_ntfs_inos;
+	err = -ENOENT;
+	for (i = 0; i < base_ni->nr_extents; i++) {
+		if (ni != extent_nis[i])
+			continue;
+		extent_nis += i;
+		base_ni->nr_extents--;
+		memmove(extent_nis, extent_nis + 1, (base_ni->nr_extents - i) *
+				sizeof(ntfs_inode*));
+		err = 0;
+		break;
+	}
+
+	mutex_unlock(&base_ni->extent_lock);
+
+	if (unlikely(err)) {
+		ntfs_error(vol->sb, "Extent inode 0x%lx is not attached to "
+				"its base inode 0x%lx.", mft_no,
+				base_ni->mft_no);
+		BUG();
+	}
+
+	/*
+	 * The extent inode is no longer attached to the base inode so no one
+	 * can get a reference to it any more.
+	 */
+
+	/* Mark the mft record as not in use. */
+	m->flags &= ~MFT_RECORD_IN_USE;
+
+	/* Increment the sequence number, skipping zero, if it is not zero. */
+	old_seq_no = m->sequence_number;
+	seq_no = le16_to_cpu(old_seq_no);
+	if (seq_no == 0xffff)
+		seq_no = 1;
+	else if (seq_no)
+		seq_no++;
+	m->sequence_number = cpu_to_le16(seq_no);
+
+	/*
+	 * Set the ntfs inode dirty and write it out.  We do not need to worry
+	 * about the base inode here since whatever caused the extent mft
+	 * record to be freed is guaranteed to do it already.
+	 */
+	NInoSetDirty(ni);
+	err = write_mft_record(ni, m, 0);
+	if (unlikely(err)) {
+		ntfs_error(vol->sb, "Failed to write mft record 0x%lx, not "
+				"freeing.", mft_no);
+		goto rollback;
+	}
+rollback_error:
+	/* Unmap and throw away the now freed extent inode. */
+	unmap_extent_mft_record(ni);
+	ntfs_clear_extent_inode(ni);
+
+	/* Clear the bit in the $MFT/$BITMAP corresponding to this record. */
+	down_write(&vol->mftbmp_lock);
+	err = ntfs_bitmap_clear_bit(vol->mftbmp_ino, mft_no);
+	up_write(&vol->mftbmp_lock);
+	if (unlikely(err)) {
+		/*
+		 * The extent inode is gone but we failed to deallocate it in
+		 * the mft bitmap.  Just emit a warning and leave the volume
+		 * dirty on umount.
+		 */
+		ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
+		NVolSetErrors(vol);
+	}
+	return 0;
+rollback:
+	/* Rollback what we did... */
+	mutex_lock(&base_ni->extent_lock);
+	extent_nis = base_ni->ext.extent_ntfs_inos;
+	if (!(base_ni->nr_extents & 3)) {
+		int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode*);
+
+		extent_nis = kmalloc(new_size, GFP_NOFS);
+		if (unlikely(!extent_nis)) {
+			ntfs_error(vol->sb, "Failed to allocate internal "
+					"buffer during rollback.%s", es);
+			mutex_unlock(&base_ni->extent_lock);
+			NVolSetErrors(vol);
+			goto rollback_error;
+		}
+		if (base_ni->nr_extents) {
+			BUG_ON(!base_ni->ext.extent_ntfs_inos);
+			memcpy(extent_nis, base_ni->ext.extent_ntfs_inos,
+					new_size - 4 * sizeof(ntfs_inode*));
+			kfree(base_ni->ext.extent_ntfs_inos);
+		}
+		base_ni->ext.extent_ntfs_inos = extent_nis;
+	}
+	m->flags |= MFT_RECORD_IN_USE;
+	m->sequence_number = old_seq_no;
+	extent_nis[base_ni->nr_extents++] = ni;
+	mutex_unlock(&base_ni->extent_lock);
+	mark_mft_record_dirty(ni);
+	return err;
+}
+#endif /* NTFS_RW */