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 // 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, 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, 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.\n",
             mft_no, base_ni->mft_no);
 
     mutex_lock(&base_ni->extent_lock);
 
     /* Make sure we are holding the only reference to the extent inode. */
     if (atomic_read(&ni->count) > 2) {
         ntfs_error(vol->sb, "Tried to free busy extent inode 0x%lx, "
                 "not freeing.", base_ni->mft_no);
         mutex_unlock(&base_ni->extent_lock);
         return -EBUSY;
     }
 
     /* Dissociate the ntfs inode from the base inode. */
     extent_nis = base_ni->ext.extent_ntfs_inos;
     err = -ENOENT;
     for (i = 0; i < base_ni->nr_extents; i++) {
         if (ni != extent_nis[i])
             continue;
         extent_nis += i;
         base_ni->nr_extents--;
         memmove(extent_nis, extent_nis + 1, (base_ni->nr_extents - i) *
                 sizeof(ntfs_inode*));
         err = 0;
         break;
     }
 
     mutex_unlock(&base_ni->extent_lock);
 
     if (unlikely(err)) {
         ntfs_error(vol->sb, "Extent inode 0x%lx is not attached to "
                 "its base inode 0x%lx.", mft_no,
                 base_ni->mft_no);
         BUG();
     }
 
     /*
      * The extent inode is no longer attached to the base inode so no one
      * can get a reference to it any more.
      */
 
     /* Mark the mft record as not in use. */
     m->flags &= ~MFT_RECORD_IN_USE;
 
     /* Increment the sequence number, skipping zero, if it is not zero. */
     old_seq_no = m->sequence_number;
     seq_no = le16_to_cpu(old_seq_no);
     if (seq_no == 0xffff)
         seq_no = 1;
     else if (seq_no)
         seq_no++;
     m->sequence_number = cpu_to_le16(seq_no);
 
     /*
      * Set the ntfs inode dirty and write it out.  We do not need to worry
      * about the base inode here since whatever caused the extent mft
      * record to be freed is guaranteed to do it already.
      */
     NInoSetDirty(ni);
     err = write_mft_record(ni, m, 0);
     if (unlikely(err)) {
         ntfs_error(vol->sb, "Failed to write mft record 0x%lx, not "
                 "freeing.", mft_no);
         goto rollback;
     }
 rollback_error:
     /* Unmap and throw away the now freed extent inode. */
     unmap_extent_mft_record(ni);
     ntfs_clear_extent_inode(ni);
 
     /* Clear the bit in the $MFT/$BITMAP corresponding to this record. */
     down_write(&vol->mftbmp_lock);
     err = ntfs_bitmap_clear_bit(vol->mftbmp_ino, mft_no);
     up_write(&vol->mftbmp_lock);
     if (unlikely(err)) {
         /*
          * The extent inode is gone but we failed to deallocate it in
          * the mft bitmap.  Just emit a warning and leave the volume
          * dirty on umount.
          */
         ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
         NVolSetErrors(vol);
     }
     return 0;
 rollback:
     /* Rollback what we did... */
     mutex_lock(&base_ni->extent_lock);
     extent_nis = base_ni->ext.extent_ntfs_inos;
     if (!(base_ni->nr_extents & 3)) {
         int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode*);
 
         extent_nis = kmalloc(new_size, GFP_NOFS);
         if (unlikely(!extent_nis)) {
             ntfs_error(vol->sb, "Failed to allocate internal "
                     "buffer during rollback.%s", es);
             mutex_unlock(&base_ni->extent_lock);
             NVolSetErrors(vol);
             goto rollback_error;
         }
         if (base_ni->nr_extents) {
             BUG_ON(!base_ni->ext.extent_ntfs_inos);
             memcpy(extent_nis, base_ni->ext.extent_ntfs_inos,
                     new_size - 4 * sizeof(ntfs_inode*));
             kfree(base_ni->ext.extent_ntfs_inos);
         }
         base_ni->ext.extent_ntfs_inos = extent_nis;
     }
     m->flags |= MFT_RECORD_IN_USE;
     m->sequence_number = old_seq_no;
     extent_nis[base_ni->nr_extents++] = ni;
     mutex_unlock(&base_ni->extent_lock);
     mark_mft_record_dirty(ni);
     return err;
 }
 #endif /* NTFS_RW */