// SPDX-License-Identifier: GPL-2.0-or-later

  /**
   * 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

   */
  
  #include <linux/buffer_head.h>

  #include <linux/slab.h>

  #include <linux/swap.h>

  #include <linux/bio.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"

  #define MAX_BHS	(PAGE_SIZE / NTFS_BLOCK_SIZE)

  /**
   * 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_SHIFT;
  	ofs = (ni->mft_no << vol->mft_record_size_bits) & ~PAGE_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_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_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 (!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 (!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 (!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_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_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 (WARN_ON(max_bhs > MAX_BHS))
  		return -EINVAL;

  	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_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_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, true);

  		do {
  			set_buffer_uptodate(bh);
  			tail = bh;
  			bh = bh->b_this_page;
  		} while (bh);
  		tail->b_this_page = head;

  		attach_page_private(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(REQ_OP_WRITE, 0, 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 (WARN_ON(max_bhs > MAX_BHS)) {
  		err = -EINVAL;
  		goto err_out;
  	}

  	/*
  	 * 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(REQ_OP_WRITE, 0, 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, 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, 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_MASK;
  		size = PAGE_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_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 (IS_ERR(rl) || unlikely(!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_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_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 (IS_ERR(rl) || unlikely(!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 (!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_SHIFT;
  	ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_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_SHIFT;

  	if (unlikely(index >= end_index)) {
  		if (unlikely(index > end_index || ofs + vol->mft_record_size >=

  				(i_size & ~PAGE_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_SHIFT;
  	ofs = (bit << vol->mft_record_size_bits) & ~PAGE_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;

  
  		/* 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_time(vi);

  		/*
  		 * 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.
  ",
  			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 */