mft.c

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#include <linux/buffer_head.h>
#include <linux/slab.h>
#include <linux/swap.h>

#include "attrib.h"
#include "aops.h"
#include "bitmap.h"
#include "debug.h"
#include "dir.h"
#include "lcnalloc.h"
#include "malloc.h"
#include "mft.h"
#include "ntfs.h"

static inline MFT_RECORD *map_mft_record_page(ntfs_inode *ni)
{
    loff_t i_size;
    ntfs_volume *vol = ni->vol;
    struct inode *mft_vi = vol->mft_ino;
    struct page *page;
    unsigned long index, end_index;
    unsigned ofs;

    BUG_ON(ni->page);
    /*
     * The index into the page cache and the offset within the page cache
     * page of the wanted mft record. FIXME: We need to check for
     * overflowing the unsigned long, but I don't think we would ever get
     * here if the volume was that big...
     */
    index = (u64)ni->mft_no << vol->mft_record_size_bits >>
            PAGE_CACHE_SHIFT;
    ofs = (ni->mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;

    i_size = i_size_read(mft_vi);
    /* The maximum valid index into the page cache for $MFT's data. */
    end_index = i_size >> PAGE_CACHE_SHIFT;

    /* If the wanted index is out of bounds the mft record doesn't exist. */
    if (unlikely(index >= end_index)) {
        if (index > end_index || (i_size & ~PAGE_CACHE_MASK) < ofs +
                vol->mft_record_size) {
            page = ERR_PTR(-ENOENT);
            ntfs_error(vol->sb, "Attempt to read mft record 0x%lx, "
                    "which is beyond the end of the mft.  "
                    "This is probably a bug in the ntfs "
                    "driver.", ni->mft_no);
            goto err_out;
        }
    }
    /* Read, map, and pin the page. */
    page = ntfs_map_page(mft_vi->i_mapping, index);
    if (likely(!IS_ERR(page))) {
        /* Catch multi sector transfer fixup errors. */
        if (likely(ntfs_is_mft_recordp((le32*)(page_address(page) +
                ofs)))) {
            ni->page = page;
            ni->page_ofs = ofs;
            return page_address(page) + ofs;
        }
        ntfs_error(vol->sb, "Mft record 0x%lx is corrupt.  "
                "Run chkdsk.", ni->mft_no);
        ntfs_unmap_page(page);
        page = ERR_PTR(-EIO);
        NVolSetErrors(vol);
    }
err_out:
    ni->page = NULL;
    ni->page_ofs = 0;
    return (void*)page;
}

MFT_RECORD *map_mft_record(ntfs_inode *ni)
{
    MFT_RECORD *m;

    ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no);

    /* Make sure the ntfs inode doesn't go away. */
    atomic_inc(&ni->count);

    /* Serialize access to this mft record. */
    mutex_lock(&ni->mrec_lock);

    m = map_mft_record_page(ni);
    if (likely(!IS_ERR(m)))
        return m;

    mutex_unlock(&ni->mrec_lock);
    atomic_dec(&ni->count);
    ntfs_error(ni->vol->sb, "Failed with error code %lu.", -PTR_ERR(m));
    return m;
}

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;
}

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;
}

MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
        ntfs_inode **ntfs_ino)
{
    MFT_RECORD *m;
    ntfs_inode *ni = NULL;
    ntfs_inode **extent_nis = NULL;
    int i;
    unsigned long mft_no = MREF(mref);
    u16 seq_no = MSEQNO(mref);
    bool destroy_ni = false;

    ntfs_debug("Mapping extent mft record 0x%lx (base mft record 0x%lx).",
            mft_no, base_ni->mft_no);
    /* Make sure the base ntfs inode doesn't go away. */
    atomic_inc(&base_ni->count);
    /*
     * Check if this extent inode has already been added to the base inode,
     * in which case just return it. If not found, add it to the base
     * inode before returning it.
     */
    mutex_lock(&base_ni->extent_lock);
    if (base_ni->nr_extents > 0) {
        extent_nis = base_ni->ext.extent_ntfs_inos;
        for (i = 0; i < base_ni->nr_extents; i++) {
            if (mft_no != extent_nis[i]->mft_no)
                continue;
            ni = extent_nis[i];
            /* Make sure the ntfs inode doesn't go away. */
            atomic_inc(&ni->count);
            break;
        }
    }
    if (likely(ni != NULL)) {
        mutex_unlock(&base_ni->extent_lock);
        atomic_dec(&base_ni->count);
        /* We found the record; just have to map and return it. */
        m = map_mft_record(ni);
        /* map_mft_record() has incremented this on success. */
        atomic_dec(&ni->count);
        if (likely(!IS_ERR(m))) {
            /* Verify the sequence number. */
            if (likely(le16_to_cpu(m->sequence_number) == seq_no)) {
                ntfs_debug("Done 1.");
                *ntfs_ino = ni;
                return m;
            }
            unmap_mft_record(ni);
            ntfs_error(base_ni->vol->sb, "Found stale extent mft "
                    "reference! Corrupt filesystem. "
                    "Run chkdsk.");
            return ERR_PTR(-EIO);
        }
map_err_out:
        ntfs_error(base_ni->vol->sb, "Failed to map extent "
                "mft record, error code %ld.", -PTR_ERR(m));
        return m;
    }
    /* Record wasn't there. Get a new ntfs inode and initialize it. */
    ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no);
    if (unlikely(!ni)) {
        mutex_unlock(&base_ni->extent_lock);
        atomic_dec(&base_ni->count);
        return ERR_PTR(-ENOMEM);
    }
    ni->vol = base_ni->vol;
    ni->seq_no = seq_no;
    ni->nr_extents = -1;
    ni->ext.base_ntfs_ino = base_ni;
    /* Now map the record. */
    m = map_mft_record(ni);
    if (IS_ERR(m)) {
        mutex_unlock(&base_ni->extent_lock);
        atomic_dec(&base_ni->count);
        ntfs_clear_extent_inode(ni);
        goto map_err_out;
    }
    /* Verify the sequence number if it is present. */
    if (seq_no && (le16_to_cpu(m->sequence_number) != seq_no)) {
        ntfs_error(base_ni->vol->sb, "Found stale extent mft "
                "reference! Corrupt filesystem. Run chkdsk.");
        destroy_ni = true;
        m = ERR_PTR(-EIO);
        goto unm_err_out;
    }
    /* Attach extent inode to base inode, reallocating memory if needed. */
    if (!(base_ni->nr_extents & 3)) {
        ntfs_inode **tmp;
        int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *);

        tmp = kmalloc(new_size, GFP_NOFS);
        if (unlikely(!tmp)) {
            ntfs_error(base_ni->vol->sb, "Failed to allocate "
                    "internal buffer.");
            destroy_ni = true;
            m = ERR_PTR(-ENOMEM);
            goto unm_err_out;
        }
        if (base_ni->nr_extents) {
            BUG_ON(!base_ni->ext.extent_ntfs_inos);
            memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size -
                    4 * sizeof(ntfs_inode *));
            kfree(base_ni->ext.extent_ntfs_inos);
        }
        base_ni->ext.extent_ntfs_inos = tmp;
    }
    base_ni->ext.extent_ntfs_inos[base_ni->nr_extents++] = ni;
    mutex_unlock(&base_ni->extent_lock);
    atomic_dec(&base_ni->count);
    ntfs_debug("Done 2.");
    *ntfs_ino = ni;
    return m;
unm_err_out:
    unmap_mft_record(ni);
    mutex_unlock(&base_ni->extent_lock);
    atomic_dec(&base_ni->count);
    /*
     * If the extent inode was not attached to the base inode we need to
     * release it or we will leak memory.
     */
    if (destroy_ni)
        ntfs_clear_extent_inode(ni);
    return m;
}

#ifdef NTFS_RW

void __mark_mft_record_dirty(ntfs_inode *ni)
{
    ntfs_inode *base_ni;

    ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
    BUG_ON(NInoAttr(ni));
    mark_ntfs_record_dirty(ni->page, ni->page_ofs);
    /* Determine the base vfs inode and mark it dirty, too. */
    mutex_lock(&ni->extent_lock);
    if (likely(ni->nr_extents >= 0))
        base_ni = ni;
    else
        base_ni = ni->ext.base_ntfs_ino;
    mutex_unlock(&ni->extent_lock);
    __mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC);
}

static const char *ntfs_please_email = "Please email "
        "[email protected] and say that you saw "
        "this message.  Thank you.";

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;
}

int ntfs_sync_mft_mirror(ntfs_volume *vol, const unsigned long mft_no,
        MFT_RECORD *m, int sync)
{
    struct page *page;
    unsigned int blocksize = vol->sb->s_blocksize;
    int max_bhs = vol->mft_record_size / blocksize;
    struct buffer_head *bhs[max_bhs];
    struct buffer_head *bh, *head;
    u8 *kmirr;
    runlist_element *rl;
    unsigned int block_start, block_end, m_start, m_end, page_ofs;
    int i_bhs, nr_bhs, err = 0;
    unsigned char blocksize_bits = vol->sb->s_blocksize_bits;

    ntfs_debug("Entering for inode 0x%lx.", mft_no);
    BUG_ON(!max_bhs);
    if (unlikely(!vol->mftmirr_ino)) {
        /* This could happen during umount... */
        err = ntfs_sync_mft_mirror_umount(vol, mft_no, m);
        if (likely(!err))
            return err;
        goto err_out;
    }
    /* Get the page containing the mirror copy of the mft record @m. */
    page = ntfs_map_page(vol->mftmirr_ino->i_mapping, mft_no >>
            (PAGE_CACHE_SHIFT - vol->mft_record_size_bits));
    if (IS_ERR(page)) {
        ntfs_error(vol->sb, "Failed to map mft mirror page.");
        err = PTR_ERR(page);
        goto err_out;
    }
    lock_page(page);
    BUG_ON(!PageUptodate(page));
    ClearPageUptodate(page);
    /* Offset of the mft mirror record inside the page. */
    page_ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
    /* The address in the page of the mirror copy of the mft record @m. */
    kmirr = page_address(page) + page_ofs;
    /* Copy the mst protected mft record to the mirror. */
    memcpy(kmirr, m, vol->mft_record_size);
    /* Create uptodate buffers if not present. */
    if (unlikely(!page_has_buffers(page))) {
        struct buffer_head *tail;

        bh = head = alloc_page_buffers(page, blocksize, 1);
        do {
            set_buffer_uptodate(bh);
            tail = bh;
            bh = bh->b_this_page;
        } while (bh);
        tail->b_this_page = head;
        attach_page_buffers(page, head);
    }
    bh = head = page_buffers(page);
    BUG_ON(!bh);
    rl = NULL;
    nr_bhs = 0;
    block_start = 0;
    m_start = kmirr - (u8*)page_address(page);
    m_end = m_start + vol->mft_record_size;
    do {
        block_end = block_start + blocksize;
        /* If the buffer is outside the mft record, skip it. */
        if (block_end <= m_start)
            continue;
        if (unlikely(block_start >= m_end))
            break;
        /* Need to map the buffer if it is not mapped already. */
        if (unlikely(!buffer_mapped(bh))) {
            VCN vcn;
            LCN lcn;
            unsigned int vcn_ofs;

            bh->b_bdev = vol->sb->s_bdev;
            /* Obtain the vcn and offset of the current block. */
            vcn = ((VCN)mft_no << vol->mft_record_size_bits) +
                    (block_start - m_start);
            vcn_ofs = vcn & vol->cluster_size_mask;
            vcn >>= vol->cluster_size_bits;
            if (!rl) {
                down_read(&NTFS_I(vol->mftmirr_ino)->
                        runlist.lock);
                rl = NTFS_I(vol->mftmirr_ino)->runlist.rl;
                /*
                 * $MFTMirr always has the whole of its runlist
                 * in memory.
                 */
                BUG_ON(!rl);
            }
            /* Seek to element containing target vcn. */
            while (rl->length && rl[1].vcn <= vcn)
                rl++;
            lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
            /* For $MFTMirr, only lcn >= 0 is a successful remap. */
            if (likely(lcn >= 0)) {
                /* Setup buffer head to correct block. */
                bh->b_blocknr = ((lcn <<
                        vol->cluster_size_bits) +
                        vcn_ofs) >> blocksize_bits;
                set_buffer_mapped(bh);
            } else {
                bh->b_blocknr = -1;
                ntfs_error(vol->sb, "Cannot write mft mirror "
                        "record 0x%lx because its "
                        "location on disk could not "
                        "be determined (error code "
                        "%lli).", mft_no,
                        (long long)lcn);
                err = -EIO;
            }
        }
        BUG_ON(!buffer_uptodate(bh));
        BUG_ON(!nr_bhs && (m_start != block_start));
        BUG_ON(nr_bhs >= max_bhs);
        bhs[nr_bhs++] = bh;
        BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
    } while (block_start = block_end, (bh = bh->b_this_page) != head);
    if (unlikely(rl))
        up_read(&NTFS_I(vol->mftmirr_ino)->runlist.lock);
    if (likely(!err)) {
        /* Lock buffers and start synchronous write i/o on them. */
        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
            struct buffer_head *tbh = bhs[i_bhs];

            if (!trylock_buffer(tbh))
                BUG();
            BUG_ON(!buffer_uptodate(tbh));
            clear_buffer_dirty(tbh);
            get_bh(tbh);
            tbh->b_end_io = end_buffer_write_sync;
            submit_bh(WRITE, tbh);
        }
        /* Wait on i/o completion of buffers. */
        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
            struct buffer_head *tbh = bhs[i_bhs];

            wait_on_buffer(tbh);
            if (unlikely(!buffer_uptodate(tbh))) {
                err = -EIO;
                /*
                 * Set the buffer uptodate so the page and
                 * buffer states do not become out of sync.
                 */
                set_buffer_uptodate(tbh);
            }
        }
    } else /* if (unlikely(err)) */ {
        /* Clean the buffers. */
        for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
            clear_buffer_dirty(bhs[i_bhs]);
    }
    /* Current state: all buffers are clean, unlocked, and uptodate. */
    /* Remove the mst protection fixups again. */
    post_write_mst_fixup((NTFS_RECORD*)kmirr);
    flush_dcache_page(page);
    SetPageUptodate(page);
    unlock_page(page);
    ntfs_unmap_page(page);
    if (likely(!err)) {
        ntfs_debug("Done.");
    } else {
        ntfs_error(vol->sb, "I/O error while writing mft mirror "
                "record 0x%lx!", mft_no);
err_out:
        ntfs_error(vol->sb, "Failed to synchronize $MFTMirr (error "
                "code %i).  Volume will be left marked dirty "
                "on umount.  Run ntfsfix on the partition "
                "after umounting to correct this.", -err);
        NVolSetErrors(vol);
    }
    return err;
}

int write_mft_record_nolock(ntfs_inode *ni, MFT_RECORD *m, int sync)
{
    ntfs_volume *vol = ni->vol;
    struct page *page = ni->page;
    unsigned int blocksize = vol->sb->s_blocksize;
    unsigned char blocksize_bits = vol->sb->s_blocksize_bits;
    int max_bhs = vol->mft_record_size / blocksize;
    struct buffer_head *bhs[max_bhs];
    struct buffer_head *bh, *head;
    runlist_element *rl;
    unsigned int block_start, block_end, m_start, m_end;
    int i_bhs, nr_bhs, err = 0;

    ntfs_debug("Entering for inode 0x%lx.", ni->mft_no);
    BUG_ON(NInoAttr(ni));
    BUG_ON(!max_bhs);
    BUG_ON(!PageLocked(page));
    /*
     * If the ntfs_inode is clean no need to do anything.  If it is dirty,
     * mark it as clean now so that it can be redirtied later on if needed.
     * There is no danger of races since the caller is holding the locks
     * for the mft record @m and the page it is in.
     */
    if (!NInoTestClearDirty(ni))
        goto done;
    bh = head = page_buffers(page);
    BUG_ON(!bh);
    rl = NULL;
    nr_bhs = 0;
    block_start = 0;
    m_start = ni->page_ofs;
    m_end = m_start + vol->mft_record_size;
    do {
        block_end = block_start + blocksize;
        /* If the buffer is outside the mft record, skip it. */
        if (block_end <= m_start)
            continue;
        if (unlikely(block_start >= m_end))
            break;
        /*
         * If this block is not the first one in the record, we ignore
         * the buffer's dirty state because we could have raced with a
         * parallel mark_ntfs_record_dirty().
         */
        if (block_start == m_start) {
            /* This block is the first one in the record. */
            if (!buffer_dirty(bh)) {
                BUG_ON(nr_bhs);
                /* Clean records are not written out. */
                break;
            }
        }
        /* Need to map the buffer if it is not mapped already. */
        if (unlikely(!buffer_mapped(bh))) {
            VCN vcn;
            LCN lcn;
            unsigned int vcn_ofs;

            bh->b_bdev = vol->sb->s_bdev;
            /* Obtain the vcn and offset of the current block. */
            vcn = ((VCN)ni->mft_no << vol->mft_record_size_bits) +
                    (block_start - m_start);
            vcn_ofs = vcn & vol->cluster_size_mask;
            vcn >>= vol->cluster_size_bits;
            if (!rl) {
                down_read(&NTFS_I(vol->mft_ino)->runlist.lock);
                rl = NTFS_I(vol->mft_ino)->runlist.rl;
                BUG_ON(!rl);
            }
            /* Seek to element containing target vcn. */
            while (rl->length && rl[1].vcn <= vcn)
                rl++;
            lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
            /* For $MFT, only lcn >= 0 is a successful remap. */
            if (likely(lcn >= 0)) {
                /* Setup buffer head to correct block. */
                bh->b_blocknr = ((lcn <<
                        vol->cluster_size_bits) +
                        vcn_ofs) >> blocksize_bits;
                set_buffer_mapped(bh);
            } else {
                bh->b_blocknr = -1;
                ntfs_error(vol->sb, "Cannot write mft record "
                        "0x%lx because its location "
                        "on disk could not be "
                        "determined (error code %lli).",
                        ni->mft_no, (long long)lcn);
                err = -EIO;
            }
        }
        BUG_ON(!buffer_uptodate(bh));
        BUG_ON(!nr_bhs && (m_start != block_start));
        BUG_ON(nr_bhs >= max_bhs);
        bhs[nr_bhs++] = bh;
        BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end));
    } while (block_start = block_end, (bh = bh->b_this_page) != head);
    if (unlikely(rl))
        up_read(&NTFS_I(vol->mft_ino)->runlist.lock);
    if (!nr_bhs)
        goto done;
    if (unlikely(err))
        goto cleanup_out;
    /* Apply the mst protection fixups. */
    err = pre_write_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size);
    if (err) {
        ntfs_error(vol->sb, "Failed to apply mst fixups!");
        goto cleanup_out;
    }
    flush_dcache_mft_record_page(ni);
    /* Lock buffers and start synchronous write i/o on them. */
    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
        struct buffer_head *tbh = bhs[i_bhs];

        if (!trylock_buffer(tbh))
            BUG();
        BUG_ON(!buffer_uptodate(tbh));
        clear_buffer_dirty(tbh);
        get_bh(tbh);
        tbh->b_end_io = end_buffer_write_sync;
        submit_bh(WRITE, tbh);
    }
    /* Synchronize the mft mirror now if not @sync. */
    if (!sync && ni->mft_no < vol->mftmirr_size)
        ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
    /* Wait on i/o completion of buffers. */
    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) {
        struct buffer_head *tbh = bhs[i_bhs];

        wait_on_buffer(tbh);
        if (unlikely(!buffer_uptodate(tbh))) {
            err = -EIO;
            /*
             * Set the buffer uptodate so the page and buffer
             * states do not become out of sync.
             */
            if (PageUptodate(page))
                set_buffer_uptodate(tbh);
        }
    }
    /* If @sync, now synchronize the mft mirror. */
    if (sync && ni->mft_no < vol->mftmirr_size)
        ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync);
    /* Remove the mst protection fixups again. */
    post_write_mst_fixup((NTFS_RECORD*)m);
    flush_dcache_mft_record_page(ni);
    if (unlikely(err)) {
        /* I/O error during writing.  This is really bad! */
        ntfs_error(vol->sb, "I/O error while writing mft record "
                "0x%lx!  Marking base inode as bad.  You "
                "should unmount the volume and run chkdsk.",
                ni->mft_no);
        goto err_out;
    }
done:
    ntfs_debug("Done.");
    return 0;
cleanup_out:
    /* Clean the buffers. */
    for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++)
        clear_buffer_dirty(bhs[i_bhs]);
err_out:
    /*
     * Current state: all buffers are clean, unlocked, and uptodate.
     * The caller should mark the base inode as bad so that no more i/o
     * happens.  ->clear_inode() will still be invoked so all extent inodes
     * and other allocated memory will be freed.
     */
    if (err == -ENOMEM) {
        ntfs_error(vol->sb, "Not enough memory to write mft record.  "
                "Redirtying so the write is retried later.");
        mark_mft_record_dirty(ni);
        err = 0;
    } else
        NVolSetErrors(vol);
    return err;
}

bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
        const MFT_RECORD *m, ntfs_inode **locked_ni)
{
    struct super_block *sb = vol->sb;
    struct inode *mft_vi = vol->mft_ino;
    struct inode *vi;
    ntfs_inode *ni, *eni, **extent_nis;
    int i;
    ntfs_attr na;

    ntfs_debug("Entering for inode 0x%lx.", mft_no);
    /*
     * Normally we do not return a locked inode so set @locked_ni to NULL.
     */
    BUG_ON(!locked_ni);
    *locked_ni = NULL;
    /*
     * Check if the inode corresponding to this mft record is in the VFS
     * inode cache and obtain a reference to it if it is.
     */
    ntfs_debug("Looking for inode 0x%lx in icache.", mft_no);
    na.mft_no = mft_no;
    na.name = NULL;
    na.name_len = 0;
    na.type = AT_UNUSED;
    /*
     * Optimize inode 0, i.e. $MFT itself, since we have it in memory and
     * we get here for it rather often.
     */
    if (!mft_no) {
        /* Balance the below iput(). */
        vi = igrab(mft_vi);
        BUG_ON(vi != mft_vi);
    } else {
        /*
         * Have to use ilookup5_nowait() since ilookup5() waits for the
         * inode lock which causes ntfs to deadlock when a concurrent
         * inode write via the inode dirty code paths and the page
         * dirty code path of the inode dirty code path when writing
         * $MFT occurs.
         */
        vi = ilookup5_nowait(sb, mft_no, (test_t)ntfs_test_inode, &na);
    }
    if (vi) {
        ntfs_debug("Base inode 0x%lx is in icache.", mft_no);
        /* The inode is in icache. */
        ni = NTFS_I(vi);
        /* Take a reference to the ntfs inode. */
        atomic_inc(&ni->count);
        /* If the inode is dirty, do not write this record. */
        if (NInoDirty(ni)) {
            ntfs_debug("Inode 0x%lx is dirty, do not write it.",
                    mft_no);
            atomic_dec(&ni->count);
            iput(vi);
            return false;
        }
        ntfs_debug("Inode 0x%lx is not dirty.", mft_no);
        /* The inode is not dirty, try to take the mft record lock. */
        if (unlikely(!mutex_trylock(&ni->mrec_lock))) {
            ntfs_debug("Mft record 0x%lx is already locked, do "
                    "not write it.", mft_no);
            atomic_dec(&ni->count);
            iput(vi);
            return false;
        }
        ntfs_debug("Managed to lock mft record 0x%lx, write it.",
                mft_no);
        /*
         * The write has to occur while we hold the mft record lock so
         * return the locked ntfs inode.
         */
        *locked_ni = ni;
        return true;
    }
    ntfs_debug("Inode 0x%lx is not in icache.", mft_no);
    /* The inode is not in icache. */
    /* Write the record if it is not a mft record (type "FILE"). */
    if (!ntfs_is_mft_record(m->magic)) {
        ntfs_debug("Mft record 0x%lx is not a FILE record, write it.",
                mft_no);
        return true;
    }
    /* Write the mft record if it is a base inode. */
    if (!m->base_mft_record) {
        ntfs_debug("Mft record 0x%lx is a base record, write it.",
                mft_no);
        return true;
    }
    /*
     * This is an extent mft record.  Check if the inode corresponding to
     * its base mft record is in icache and obtain a reference to it if it
     * is.
     */
    na.mft_no = MREF_LE(m->base_mft_record);
    ntfs_debug("Mft record 0x%lx is an extent record.  Looking for base "
            "inode 0x%lx in icache.", mft_no, na.mft_no);
    if (!na.mft_no) {
        /* Balance the below iput(). */
        vi = igrab(mft_vi);
        BUG_ON(vi != mft_vi);
    } else
        vi = ilookup5_nowait(sb, na.mft_no, (test_t)ntfs_test_inode,
                &na);
    if (!vi) {
        /*
         * The base inode is not in icache, write this extent mft
         * record.
         */
        ntfs_debug("Base inode 0x%lx is not in icache, write the "
                "extent record.", na.mft_no);
        return true;
    }
    ntfs_debug("Base inode 0x%lx is in icache.", na.mft_no);
    /*
     * The base inode is in icache.  Check if it has the extent inode
     * corresponding to this extent mft record attached.
     */
    ni = NTFS_I(vi);
    mutex_lock(&ni->extent_lock);
    if (ni->nr_extents <= 0) {
        /*
         * The base inode has no attached extent inodes, write this
         * extent mft record.
         */
        mutex_unlock(&ni->extent_lock);
        iput(vi);
        ntfs_debug("Base inode 0x%lx has no attached extent inodes, "
                "write the extent record.", na.mft_no);
        return true;
    }
    /* Iterate over the attached extent inodes. */
    extent_nis = ni->ext.extent_ntfs_inos;
    for (eni = NULL, i = 0; i < ni->nr_extents; ++i) {
        if (mft_no == extent_nis[i]->mft_no) {
            /*
             * Found the extent inode corresponding to this extent
             * mft record.
             */
            eni = extent_nis[i];
            break;
        }
    }
    /*
     * If the extent inode was not attached to the base inode, write this
     * extent mft record.
     */
    if (!eni) {
        mutex_unlock(&ni->extent_lock);
        iput(vi);
        ntfs_debug("Extent inode 0x%lx is not attached to its base "
                "inode 0x%lx, write the extent record.",
                mft_no, na.mft_no);
        return true;
    }
    ntfs_debug("Extent inode 0x%lx is attached to its base inode 0x%lx.",
            mft_no, na.mft_no);
    /* Take a reference to the extent ntfs inode. */
    atomic_inc(&eni->count);
    mutex_unlock(&ni->extent_lock);
    /*
     * Found the extent inode coresponding to this extent mft record.
     * Try to take the mft record lock.
     */
    if (unlikely(!mutex_trylock(&eni->mrec_lock))) {
        atomic_dec(&eni->count);
        iput(vi);
        ntfs_debug("Extent mft record 0x%lx is already locked, do "
                "not write it.", mft_no);
        return false;
    }
    ntfs_debug("Managed to lock extent mft record 0x%lx, write it.",
            mft_no);
    if (NInoTestClearDirty(eni))
        ntfs_debug("Extent inode 0x%lx is dirty, marking it clean.",
                mft_no);
    /*
     * The write has to occur while we hold the mft record lock so return
     * the locked extent ntfs inode.
     */
    *locked_ni = eni;
    return true;
}

static const char *es = "  Leaving inconsistent metadata.  Unmount and run "
        "chkdsk.";

static int ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(ntfs_volume *vol,
        ntfs_inode *base_ni)
{
    s64 pass_end, ll, data_pos, pass_start, ofs, bit;
    unsigned long flags;
    struct address_space *mftbmp_mapping;
    u8 *buf, *byte;
    struct page *page;
    unsigned int page_ofs, size;
    u8 pass, b;

    ntfs_debug("Searching for free mft record in the currently "
            "initialized mft bitmap.");
    mftbmp_mapping = vol->mftbmp_ino->i_mapping;
    /*
     * Set the end of the pass making sure we do not overflow the mft
     * bitmap.
     */
    read_lock_irqsave(&NTFS_I(vol->mft_ino)->size_lock, flags);
    pass_end = NTFS_I(vol->mft_ino)->allocated_size >>
            vol->mft_record_size_bits;
    read_unlock_irqrestore(&NTFS_I(vol->mft_ino)->size_lock, flags);
    read_lock_irqsave(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
    ll = NTFS_I(vol->mftbmp_ino)->initialized_size << 3;
    read_unlock_irqrestore(&NTFS_I(vol->mftbmp_ino)->size_lock, flags);
    if (pass_end > ll)
        pass_end = ll;
    pass = 1;
    if (!base_ni)
        data_pos = vol->mft_data_pos;
    else
        data_pos = base_ni->mft_no + 1;
    if (data_pos < 24)
        data_pos = 24;
    if (data_pos >= pass_end) {
        data_pos = 24;
        pass = 2;
        /* This happens on a freshly formatted volume. */
        if (data_pos >= pass_end)
            return -ENOSPC;
    }
    pass_start = data_pos;
    ntfs_debug("Starting bitmap search: pass %u, pass_start 0x%llx, "
            "pass_end 0x%llx, data_pos 0x%llx.", pass,
            (long long)pass_start, (long long)pass_end,
            (long long)data_pos);
    /* Loop until a free mft record is found. */
    for (; pass <= 2;) {
        /* Cap size to pass_end. */
        ofs = data_pos >> 3;
        page_ofs = ofs & ~PAGE_CACHE_MASK;
        size = PAGE_CACHE_SIZE - page_ofs;
        ll = ((pass_end + 7) >> 3) - ofs;
        if (size > ll)
            size = ll;
        size <<= 3;
        /*
         * If we are still within the active pass, search the next page
         * for a zero bit.
         */
        if (size) {
            page = ntfs_map_page(mftbmp_mapping,
                    ofs >> PAGE_CACHE_SHIFT);
            if (IS_ERR(page)) {
                ntfs_error(vol->sb, "Failed to read mft "
                        "bitmap, aborting.");
                return PTR_ERR(page);
            }
            buf = (u8*)page_address(page) + page_ofs;
            bit = data_pos & 7;
            data_pos &= ~7ull;
            ntfs_debug("Before inner for loop: size 0x%x, "
                    "data_pos 0x%llx, bit 0x%llx", size,
                    (long long)data_pos, (long long)bit);
            for (; bit < size && data_pos + bit < pass_end;
                    bit &= ~7ull, bit += 8) {
                byte = buf + (bit >> 3);
                if (*byte == 0xff)
                    continue;
                b = ffz((unsigned long)*byte);
                if (b < 8 && b >= (bit & 7)) {
                    ll = data_pos + (bit & ~7ull) + b;
                    if (unlikely(ll > (1ll << 32))) {
                        ntfs_unmap_page(page);
                        return -ENOSPC;
                    }
                    *byte |= 1 << b;
                    flush_dcache_page(page);
                    set_page_dirty(page);
                    ntfs_unmap_page(page);
                    ntfs_debug("Done.  (Found and "
                            "allocated mft record "
                            "0x%llx.)",
                            (long long)ll);
                    return ll;
                }
            }
            ntfs_debug("After inner for loop: size 0x%x, "
                    "data_pos 0x%llx, bit 0x%llx", size,
                    (long long)data_pos, (long long)bit);
            data_pos += size;
            ntfs_unmap_page(page);
            /*
             * If the end of the pass has not been reached yet,
             * continue searching the mft bitmap for a zero bit.
             */
            if (data_pos < pass_end)
                continue;
        }
        /* Do the next pass. */
        if (++pass == 2) {
            /*
             * Starting the second pass, in which we scan the first
             * part of the zone which we omitted earlier.
             */
            pass_end = pass_start;
            data_pos = pass_start = 24;
            ntfs_debug("pass %i, pass_start 0x%llx, pass_end "
                    "0x%llx.", pass, (long long)pass_start,
                    (long long)pass_end);
            if (data_pos >= pass_end)
                break;
        }
    }
    /* No free mft records in currently initialized mft bitmap. */
    ntfs_debug("Done.  (No free mft records left in currently initialized "
            "mft bitmap.)");
    return -ENOSPC;
}

static int ntfs_mft_bitmap_extend_allocation_nolock(ntfs_volume *vol)
{
    LCN lcn;
    s64 ll;
    unsigned long flags;
    struct page *page;
    ntfs_inode *mft_ni, *mftbmp_ni;
    runlist_element *rl, *rl2 = NULL;
    ntfs_attr_search_ctx *ctx = NULL;
    MFT_RECORD *mrec;
    ATTR_RECORD *a = NULL;
    int ret, mp_size;
    u32 old_alen = 0;
    u8 *b, tb;
    struct {
        u8 added_cluster:1;
        u8 added_run:1;
        u8 mp_rebuilt:1;
    } status = { 0, 0, 0 };

    ntfs_debug("Extending mft bitmap allocation.");
    mft_ni = NTFS_I(vol->mft_ino);
    mftbmp_ni = NTFS_I(vol->mftbmp_ino);
    /*
     * Determine the last lcn of the mft bitmap.  The allocated size of the
     * mft bitmap cannot be zero so we are ok to do this.
     */
    down_write(&mftbmp_ni->runlist.lock);
    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
    ll = mftbmp_ni->allocated_size;
    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
    rl = ntfs_attr_find_vcn_nolock(mftbmp_ni,
            (ll - 1) >> vol->cluster_size_bits, NULL);
    if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
        up_write(&mftbmp_ni->runlist.lock);
        ntfs_error(vol->sb, "Failed to determine last allocated "
                "cluster of mft bitmap attribute.");
        if (!IS_ERR(rl))
            ret = -EIO;
        else
            ret = PTR_ERR(rl);
        return ret;
    }
    lcn = rl->lcn + rl->length;
    ntfs_debug("Last lcn of mft bitmap attribute is 0x%llx.",
            (long long)lcn);
    /*
     * Attempt to get the cluster following the last allocated cluster by
     * hand as it may be in the MFT zone so the allocator would not give it
     * to us.
     */
    ll = lcn >> 3;
    page = ntfs_map_page(vol->lcnbmp_ino->i_mapping,
            ll >> PAGE_CACHE_SHIFT);
    if (IS_ERR(page)) {
        up_write(&mftbmp_ni->runlist.lock);
        ntfs_error(vol->sb, "Failed to read from lcn bitmap.");
        return PTR_ERR(page);
    }
    b = (u8*)page_address(page) + (ll & ~PAGE_CACHE_MASK);
    tb = 1 << (lcn & 7ull);
    down_write(&vol->lcnbmp_lock);
    if (*b != 0xff && !(*b & tb)) {
        /* Next cluster is free, allocate it. */
        *b |= tb;
        flush_dcache_page(page);
        set_page_dirty(page);
        up_write(&vol->lcnbmp_lock);
        ntfs_unmap_page(page);
        /* Update the mft bitmap runlist. */
        rl->length++;
        rl[1].vcn++;
        status.added_cluster = 1;
        ntfs_debug("Appending one cluster to mft bitmap.");
    } else {
        up_write(&vol->lcnbmp_lock);
        ntfs_unmap_page(page);
        /* Allocate a cluster from the DATA_ZONE. */
        rl2 = ntfs_cluster_alloc(vol, rl[1].vcn, 1, lcn, DATA_ZONE,
                true);
        if (IS_ERR(rl2)) {
            up_write(&mftbmp_ni->runlist.lock);
            ntfs_error(vol->sb, "Failed to allocate a cluster for "
                    "the mft bitmap.");
            return PTR_ERR(rl2);
        }
        rl = ntfs_runlists_merge(mftbmp_ni->runlist.rl, rl2);
        if (IS_ERR(rl)) {
            up_write(&mftbmp_ni->runlist.lock);
            ntfs_error(vol->sb, "Failed to merge runlists for mft "
                    "bitmap.");
            if (ntfs_cluster_free_from_rl(vol, rl2)) {
                ntfs_error(vol->sb, "Failed to deallocate "
                        "allocated cluster.%s", es);
                NVolSetErrors(vol);
            }
            ntfs_free(rl2);
            return PTR_ERR(rl);
        }
        mftbmp_ni->runlist.rl = rl;
        status.added_run = 1;
        ntfs_debug("Adding one run to mft bitmap.");
        /* Find the last run in the new runlist. */
        for (; rl[1].length; rl++)
            ;
    }
    /*
     * Update the attribute record as well.  Note: @rl is the last
     * (non-terminator) runlist element of mft bitmap.
     */
    mrec = map_mft_record(mft_ni);
    if (IS_ERR(mrec)) {
        ntfs_error(vol->sb, "Failed to map mft record.");
        ret = PTR_ERR(mrec);
        goto undo_alloc;
    }
    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
    if (unlikely(!ctx)) {
        ntfs_error(vol->sb, "Failed to get search context.");
        ret = -ENOMEM;
        goto undo_alloc;
    }
    ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
            mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
            0, ctx);
    if (unlikely(ret)) {
        ntfs_error(vol->sb, "Failed to find last attribute extent of "
                "mft bitmap attribute.");
        if (ret == -ENOENT)
            ret = -EIO;
        goto undo_alloc;
    }
    a = ctx->attr;
    ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
    /* Search back for the previous last allocated cluster of mft bitmap. */
    for (rl2 = rl; rl2 > mftbmp_ni->runlist.rl; rl2--) {
        if (ll >= rl2->vcn)
            break;
    }
    BUG_ON(ll < rl2->vcn);
    BUG_ON(ll >= rl2->vcn + rl2->length);
    /* Get the size for the new mapping pairs array for this extent. */
    mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
    if (unlikely(mp_size <= 0)) {
        ntfs_error(vol->sb, "Get size for mapping pairs failed for "
                "mft bitmap attribute extent.");
        ret = mp_size;
        if (!ret)
            ret = -EIO;
        goto undo_alloc;
    }
    /* Expand the attribute record if necessary. */
    old_alen = le32_to_cpu(a->length);
    ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
            le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
    if (unlikely(ret)) {
        if (ret != -ENOSPC) {
            ntfs_error(vol->sb, "Failed to resize attribute "
                    "record for mft bitmap attribute.");
            goto undo_alloc;
        }
        // TODO: Deal with this by moving this extent to a new mft
        // record or by starting a new extent in a new mft record or by
        // moving other attributes out of this mft record.
        // Note: It will need to be a special mft record and if none of
        // those are available it gets rather complicated...
        ntfs_error(vol->sb, "Not enough space in this mft record to "
                "accommodate extended mft bitmap attribute "
                "extent.  Cannot handle this yet.");
        ret = -EOPNOTSUPP;
        goto undo_alloc;
    }
    status.mp_rebuilt = 1;
    /* Generate the mapping pairs array directly into the attr record. */
    ret = ntfs_mapping_pairs_build(vol, (u8*)a +
            le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
            mp_size, rl2, ll, -1, NULL);
    if (unlikely(ret)) {
        ntfs_error(vol->sb, "Failed to build mapping pairs array for "
                "mft bitmap attribute.");
        goto undo_alloc;
    }
    /* Update the highest_vcn. */
    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
    /*
     * We now have extended the mft bitmap allocated_size by one cluster.
     * Reflect this in the ntfs_inode structure and the attribute record.
     */
    if (a->data.non_resident.lowest_vcn) {
        /*
         * We are not in the first attribute extent, switch to it, but
         * first ensure the changes will make it to disk later.
         */
        flush_dcache_mft_record_page(ctx->ntfs_ino);
        mark_mft_record_dirty(ctx->ntfs_ino);
        ntfs_attr_reinit_search_ctx(ctx);
        ret = ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
                mftbmp_ni->name_len, CASE_SENSITIVE, 0, NULL,
                0, ctx);
        if (unlikely(ret)) {
            ntfs_error(vol->sb, "Failed to find first attribute "
                    "extent of mft bitmap attribute.");
            goto restore_undo_alloc;
        }
        a = ctx->attr;
    }
    write_lock_irqsave(&mftbmp_ni->size_lock, flags);
    mftbmp_ni->allocated_size += vol->cluster_size;
    a->data.non_resident.allocated_size =
            cpu_to_sle64(mftbmp_ni->allocated_size);
    write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
    /* Ensure the changes make it to disk. */
    flush_dcache_mft_record_page(ctx->ntfs_ino);
    mark_mft_record_dirty(ctx->ntfs_ino);
    ntfs_attr_put_search_ctx(ctx);
    unmap_mft_record(mft_ni);
    up_write(&mftbmp_ni->runlist.lock);
    ntfs_debug("Done.");
    return 0;
restore_undo_alloc:
    ntfs_attr_reinit_search_ctx(ctx);
    if (ntfs_attr_lookup(mftbmp_ni->type, mftbmp_ni->name,
            mftbmp_ni->name_len, CASE_SENSITIVE, rl[1].vcn, NULL,
            0, ctx)) {
        ntfs_error(vol->sb, "Failed to find last attribute extent of "
                "mft bitmap attribute.%s", es);
        write_lock_irqsave(&mftbmp_ni->size_lock, flags);
        mftbmp_ni->allocated_size += vol->cluster_size;
        write_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(mft_ni);
        up_write(&mftbmp_ni->runlist.lock);
        /*
         * The only thing that is now wrong is ->allocated_size of the
         * base attribute extent which chkdsk should be able to fix.
         */
        NVolSetErrors(vol);
        return ret;
    }
    a = ctx->attr;
    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 2);
undo_alloc:
    if (status.added_cluster) {
        /* Truncate the last run in the runlist by one cluster. */
        rl->length--;
        rl[1].vcn--;
    } else if (status.added_run) {
        lcn = rl->lcn;
        /* Remove the last run from the runlist. */
        rl->lcn = rl[1].lcn;
        rl->length = 0;
    }
    /* Deallocate the cluster. */
    down_write(&vol->lcnbmp_lock);
    if (ntfs_bitmap_clear_bit(vol->lcnbmp_ino, lcn)) {
        ntfs_error(vol->sb, "Failed to free allocated cluster.%s", es);
        NVolSetErrors(vol);
    }
    up_write(&vol->lcnbmp_lock);
    if (status.mp_rebuilt) {
        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
                a->data.non_resident.mapping_pairs_offset),
                old_alen - le16_to_cpu(
                a->data.non_resident.mapping_pairs_offset),
                rl2, ll, -1, NULL)) {
            ntfs_error(vol->sb, "Failed to restore mapping pairs "
                    "array.%s", es);
            NVolSetErrors(vol);
        }
        if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
            ntfs_error(vol->sb, "Failed to restore attribute "
                    "record.%s", es);
            NVolSetErrors(vol);
        }
        flush_dcache_mft_record_page(ctx->ntfs_ino);
        mark_mft_record_dirty(ctx->ntfs_ino);
    }
    if (ctx)
        ntfs_attr_put_search_ctx(ctx);
    if (!IS_ERR(mrec))
        unmap_mft_record(mft_ni);
    up_write(&mftbmp_ni->runlist.lock);
    return ret;
}

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;
}

static int ntfs_mft_data_extend_allocation_nolock(ntfs_volume *vol)
{
    LCN lcn;
    VCN old_last_vcn;
    s64 min_nr, nr, ll;
    unsigned long flags;
    ntfs_inode *mft_ni;
    runlist_element *rl, *rl2;
    ntfs_attr_search_ctx *ctx = NULL;
    MFT_RECORD *mrec;
    ATTR_RECORD *a = NULL;
    int ret, mp_size;
    u32 old_alen = 0;
    bool mp_rebuilt = false;

    ntfs_debug("Extending mft data allocation.");
    mft_ni = NTFS_I(vol->mft_ino);
    /*
     * Determine the preferred allocation location, i.e. the last lcn of
     * the mft data attribute.  The allocated size of the mft data
     * attribute cannot be zero so we are ok to do this.
     */
    down_write(&mft_ni->runlist.lock);
    read_lock_irqsave(&mft_ni->size_lock, flags);
    ll = mft_ni->allocated_size;
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    rl = ntfs_attr_find_vcn_nolock(mft_ni,
            (ll - 1) >> vol->cluster_size_bits, NULL);
    if (unlikely(IS_ERR(rl) || !rl->length || rl->lcn < 0)) {
        up_write(&mft_ni->runlist.lock);
        ntfs_error(vol->sb, "Failed to determine last allocated "
                "cluster of mft data attribute.");
        if (!IS_ERR(rl))
            ret = -EIO;
        else
            ret = PTR_ERR(rl);
        return ret;
    }
    lcn = rl->lcn + rl->length;
    ntfs_debug("Last lcn of mft data attribute is 0x%llx.", (long long)lcn);
    /* Minimum allocation is one mft record worth of clusters. */
    min_nr = vol->mft_record_size >> vol->cluster_size_bits;
    if (!min_nr)
        min_nr = 1;
    /* Want to allocate 16 mft records worth of clusters. */
    nr = vol->mft_record_size << 4 >> vol->cluster_size_bits;
    if (!nr)
        nr = min_nr;
    /* Ensure we do not go above 2^32-1 mft records. */
    read_lock_irqsave(&mft_ni->size_lock, flags);
    ll = mft_ni->allocated_size;
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
            vol->mft_record_size_bits >= (1ll << 32))) {
        nr = min_nr;
        if (unlikely((ll + (nr << vol->cluster_size_bits)) >>
                vol->mft_record_size_bits >= (1ll << 32))) {
            ntfs_warning(vol->sb, "Cannot allocate mft record "
                    "because the maximum number of inodes "
                    "(2^32) has already been reached.");
            up_write(&mft_ni->runlist.lock);
            return -ENOSPC;
        }
    }
    ntfs_debug("Trying mft data allocation with %s cluster count %lli.",
            nr > min_nr ? "default" : "minimal", (long long)nr);
    old_last_vcn = rl[1].vcn;
    do {
        rl2 = ntfs_cluster_alloc(vol, old_last_vcn, nr, lcn, MFT_ZONE,
                true);
        if (likely(!IS_ERR(rl2)))
            break;
        if (PTR_ERR(rl2) != -ENOSPC || nr == min_nr) {
            ntfs_error(vol->sb, "Failed to allocate the minimal "
                    "number of clusters (%lli) for the "
                    "mft data attribute.", (long long)nr);
            up_write(&mft_ni->runlist.lock);
            return PTR_ERR(rl2);
        }
        /*
         * There is not enough space to do the allocation, but there
         * might be enough space to do a minimal allocation so try that
         * before failing.
         */
        nr = min_nr;
        ntfs_debug("Retrying mft data allocation with minimal cluster "
                "count %lli.", (long long)nr);
    } while (1);
    rl = ntfs_runlists_merge(mft_ni->runlist.rl, rl2);
    if (IS_ERR(rl)) {
        up_write(&mft_ni->runlist.lock);
        ntfs_error(vol->sb, "Failed to merge runlists for mft data "
                "attribute.");
        if (ntfs_cluster_free_from_rl(vol, rl2)) {
            ntfs_error(vol->sb, "Failed to deallocate clusters "
                    "from the mft data attribute.%s", es);
            NVolSetErrors(vol);
        }
        ntfs_free(rl2);
        return PTR_ERR(rl);
    }
    mft_ni->runlist.rl = rl;
    ntfs_debug("Allocated %lli clusters.", (long long)nr);
    /* Find the last run in the new runlist. */
    for (; rl[1].length; rl++)
        ;
    /* Update the attribute record as well. */
    mrec = map_mft_record(mft_ni);
    if (IS_ERR(mrec)) {
        ntfs_error(vol->sb, "Failed to map mft record.");
        ret = PTR_ERR(mrec);
        goto undo_alloc;
    }
    ctx = ntfs_attr_get_search_ctx(mft_ni, mrec);
    if (unlikely(!ctx)) {
        ntfs_error(vol->sb, "Failed to get search context.");
        ret = -ENOMEM;
        goto undo_alloc;
    }
    ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
            CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx);
    if (unlikely(ret)) {
        ntfs_error(vol->sb, "Failed to find last attribute extent of "
                "mft data attribute.");
        if (ret == -ENOENT)
            ret = -EIO;
        goto undo_alloc;
    }
    a = ctx->attr;
    ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
    /* Search back for the previous last allocated cluster of mft bitmap. */
    for (rl2 = rl; rl2 > mft_ni->runlist.rl; rl2--) {
        if (ll >= rl2->vcn)
            break;
    }
    BUG_ON(ll < rl2->vcn);
    BUG_ON(ll >= rl2->vcn + rl2->length);
    /* Get the size for the new mapping pairs array for this extent. */
    mp_size = ntfs_get_size_for_mapping_pairs(vol, rl2, ll, -1);
    if (unlikely(mp_size <= 0)) {
        ntfs_error(vol->sb, "Get size for mapping pairs failed for "
                "mft data attribute extent.");
        ret = mp_size;
        if (!ret)
            ret = -EIO;
        goto undo_alloc;
    }
    /* Expand the attribute record if necessary. */
    old_alen = le32_to_cpu(a->length);
    ret = ntfs_attr_record_resize(ctx->mrec, a, mp_size +
            le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
    if (unlikely(ret)) {
        if (ret != -ENOSPC) {
            ntfs_error(vol->sb, "Failed to resize attribute "
                    "record for mft data attribute.");
            goto undo_alloc;
        }
        // TODO: Deal with this by moving this extent to a new mft
        // record or by starting a new extent in a new mft record or by
        // moving other attributes out of this mft record.
        // Note: Use the special reserved mft records and ensure that
        // this extent is not required to find the mft record in
        // question.  If no free special records left we would need to
        // move an existing record away, insert ours in its place, and
        // then place the moved record into the newly allocated space
        // and we would then need to update all references to this mft
        // record appropriately.  This is rather complicated...
        ntfs_error(vol->sb, "Not enough space in this mft record to "
                "accommodate extended mft data attribute "
                "extent.  Cannot handle this yet.");
        ret = -EOPNOTSUPP;
        goto undo_alloc;
    }
    mp_rebuilt = true;
    /* Generate the mapping pairs array directly into the attr record. */
    ret = ntfs_mapping_pairs_build(vol, (u8*)a +
            le16_to_cpu(a->data.non_resident.mapping_pairs_offset),
            mp_size, rl2, ll, -1, NULL);
    if (unlikely(ret)) {
        ntfs_error(vol->sb, "Failed to build mapping pairs array of "
                "mft data attribute.");
        goto undo_alloc;
    }
    /* Update the highest_vcn. */
    a->data.non_resident.highest_vcn = cpu_to_sle64(rl[1].vcn - 1);
    /*
     * We now have extended the mft data allocated_size by nr clusters.
     * Reflect this in the ntfs_inode structure and the attribute record.
     * @rl is the last (non-terminator) runlist element of mft data
     * attribute.
     */
    if (a->data.non_resident.lowest_vcn) {
        /*
         * We are not in the first attribute extent, switch to it, but
         * first ensure the changes will make it to disk later.
         */
        flush_dcache_mft_record_page(ctx->ntfs_ino);
        mark_mft_record_dirty(ctx->ntfs_ino);
        ntfs_attr_reinit_search_ctx(ctx);
        ret = ntfs_attr_lookup(mft_ni->type, mft_ni->name,
                mft_ni->name_len, CASE_SENSITIVE, 0, NULL, 0,
                ctx);
        if (unlikely(ret)) {
            ntfs_error(vol->sb, "Failed to find first attribute "
                    "extent of mft data attribute.");
            goto restore_undo_alloc;
        }
        a = ctx->attr;
    }
    write_lock_irqsave(&mft_ni->size_lock, flags);
    mft_ni->allocated_size += nr << vol->cluster_size_bits;
    a->data.non_resident.allocated_size =
            cpu_to_sle64(mft_ni->allocated_size);
    write_unlock_irqrestore(&mft_ni->size_lock, flags);
    /* Ensure the changes make it to disk. */
    flush_dcache_mft_record_page(ctx->ntfs_ino);
    mark_mft_record_dirty(ctx->ntfs_ino);
    ntfs_attr_put_search_ctx(ctx);
    unmap_mft_record(mft_ni);
    up_write(&mft_ni->runlist.lock);
    ntfs_debug("Done.");
    return 0;
restore_undo_alloc:
    ntfs_attr_reinit_search_ctx(ctx);
    if (ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
            CASE_SENSITIVE, rl[1].vcn, NULL, 0, ctx)) {
        ntfs_error(vol->sb, "Failed to find last attribute extent of "
                "mft data attribute.%s", es);
        write_lock_irqsave(&mft_ni->size_lock, flags);
        mft_ni->allocated_size += nr << vol->cluster_size_bits;
        write_unlock_irqrestore(&mft_ni->size_lock, flags);
        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(mft_ni);
        up_write(&mft_ni->runlist.lock);
        /*
         * The only thing that is now wrong is ->allocated_size of the
         * base attribute extent which chkdsk should be able to fix.
         */
        NVolSetErrors(vol);
        return ret;
    }
    ctx->attr->data.non_resident.highest_vcn =
            cpu_to_sle64(old_last_vcn - 1);
undo_alloc:
    if (ntfs_cluster_free(mft_ni, old_last_vcn, -1, ctx) < 0) {
        ntfs_error(vol->sb, "Failed to free clusters from mft data "
                "attribute.%s", es);
        NVolSetErrors(vol);
    }
    a = ctx->attr;
    if (ntfs_rl_truncate_nolock(vol, &mft_ni->runlist, old_last_vcn)) {
        ntfs_error(vol->sb, "Failed to truncate mft data attribute "
                "runlist.%s", es);
        NVolSetErrors(vol);
    }
    if (mp_rebuilt && !IS_ERR(ctx->mrec)) {
        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
                a->data.non_resident.mapping_pairs_offset),
                old_alen - le16_to_cpu(
                a->data.non_resident.mapping_pairs_offset),
                rl2, ll, -1, NULL)) {
            ntfs_error(vol->sb, "Failed to restore mapping pairs "
                    "array.%s", es);
            NVolSetErrors(vol);
        }
        if (ntfs_attr_record_resize(ctx->mrec, a, old_alen)) {
            ntfs_error(vol->sb, "Failed to restore attribute "
                    "record.%s", es);
            NVolSetErrors(vol);
        }
        flush_dcache_mft_record_page(ctx->ntfs_ino);
        mark_mft_record_dirty(ctx->ntfs_ino);
    } else if (IS_ERR(ctx->mrec)) {
        ntfs_error(vol->sb, "Failed to restore attribute search "
                "context.%s", es);
        NVolSetErrors(vol);
    }
    if (ctx)
        ntfs_attr_put_search_ctx(ctx);
    if (!IS_ERR(mrec))
        unmap_mft_record(mft_ni);
    up_write(&mft_ni->runlist.lock);
    return ret;
}

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 "
                "[email protected] 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;
}

static int ntfs_mft_record_format(const ntfs_volume *vol, const s64 mft_no)
{
    loff_t i_size;
    struct inode *mft_vi = vol->mft_ino;
    struct page *page;
    MFT_RECORD *m;
    pgoff_t index, end_index;
    unsigned int ofs;
    int err;

    ntfs_debug("Entering for mft record 0x%llx.", (long long)mft_no);
    /*
     * The index into the page cache and the offset within the page cache
     * page of the wanted mft record.
     */
    index = mft_no << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
    ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
    /* The maximum valid index into the page cache for $MFT's data. */
    i_size = i_size_read(mft_vi);
    end_index = i_size >> PAGE_CACHE_SHIFT;
    if (unlikely(index >= end_index)) {
        if (unlikely(index > end_index || ofs + vol->mft_record_size >=
                (i_size & ~PAGE_CACHE_MASK))) {
            ntfs_error(vol->sb, "Tried to format non-existing mft "
                    "record 0x%llx.", (long long)mft_no);
            return -ENOENT;
        }
    }
    /* Read, map, and pin the page containing the mft record. */
    page = ntfs_map_page(mft_vi->i_mapping, index);
    if (IS_ERR(page)) {
        ntfs_error(vol->sb, "Failed to map page containing mft record "
                "to format 0x%llx.", (long long)mft_no);
        return PTR_ERR(page);
    }
    lock_page(page);
    BUG_ON(!PageUptodate(page));
    ClearPageUptodate(page);
    m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
    err = ntfs_mft_record_layout(vol, mft_no, m);
    if (unlikely(err)) {
        ntfs_error(vol->sb, "Failed to layout mft record 0x%llx.",
                (long long)mft_no);
        SetPageUptodate(page);
        unlock_page(page);
        ntfs_unmap_page(page);
        return err;
    }
    flush_dcache_page(page);
    SetPageUptodate(page);
    unlock_page(page);
    /*
     * Make sure the mft record is written out to disk.  We could use
     * ilookup5() to check if an inode is in icache and so on but this is
     * unnecessary as ntfs_writepage() will write the dirty record anyway.
     */
    mark_ntfs_record_dirty(page, ofs);
    ntfs_unmap_page(page);
    ntfs_debug("Done.");
    return 0;
}

ntfs_inode *ntfs_mft_record_alloc(ntfs_volume *vol, const int mode,
        ntfs_inode *base_ni, MFT_RECORD **mrec)
{
    s64 ll, bit, old_data_initialized, old_data_size;
    unsigned long flags;
    struct inode *vi;
    struct page *page;
    ntfs_inode *mft_ni, *mftbmp_ni, *ni;
    ntfs_attr_search_ctx *ctx;
    MFT_RECORD *m;
    ATTR_RECORD *a;
    pgoff_t index;
    unsigned int ofs;
    int err;
    le16 seq_no, usn;
    bool record_formatted = false;

    if (base_ni) {
        ntfs_debug("Entering (allocating an extent mft record for "
                "base mft record 0x%llx).",
                (long long)base_ni->mft_no);
        /* @mode and @base_ni are mutually exclusive. */
        BUG_ON(mode);
    } else
        ntfs_debug("Entering (allocating a base mft record).");
    if (mode) {
        /* @mode and @base_ni are mutually exclusive. */
        BUG_ON(base_ni);
        /* We only support creation of normal files and directories. */
        if (!S_ISREG(mode) && !S_ISDIR(mode))
            return ERR_PTR(-EOPNOTSUPP);
    }
    BUG_ON(!mrec);
    mft_ni = NTFS_I(vol->mft_ino);
    mftbmp_ni = NTFS_I(vol->mftbmp_ino);
    down_write(&vol->mftbmp_lock);
    bit = ntfs_mft_bitmap_find_and_alloc_free_rec_nolock(vol, base_ni);
    if (bit >= 0) {
        ntfs_debug("Found and allocated free record (#1), bit 0x%llx.",
                (long long)bit);
        goto have_alloc_rec;
    }
    if (bit != -ENOSPC) {
        up_write(&vol->mftbmp_lock);
        return ERR_PTR(bit);
    }
    /*
     * No free mft records left.  If the mft bitmap already covers more
     * than the currently used mft records, the next records are all free,
     * so we can simply allocate the first unused mft record.
     * Note: We also have to make sure that the mft bitmap at least covers
     * the first 24 mft records as they are special and whilst they may not
     * be in use, we do not allocate from them.
     */
    read_lock_irqsave(&mft_ni->size_lock, flags);
    ll = mft_ni->initialized_size >> vol->mft_record_size_bits;
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
    old_data_initialized = mftbmp_ni->initialized_size;
    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
    if (old_data_initialized << 3 > ll && old_data_initialized > 3) {
        bit = ll;
        if (bit < 24)
            bit = 24;
        if (unlikely(bit >= (1ll << 32)))
            goto max_err_out;
        ntfs_debug("Found free record (#2), bit 0x%llx.",
                (long long)bit);
        goto found_free_rec;
    }
    /*
     * The mft bitmap needs to be expanded until it covers the first unused
     * mft record that we can allocate.
     * Note: The smallest mft record we allocate is mft record 24.
     */
    bit = old_data_initialized << 3;
    if (unlikely(bit >= (1ll << 32)))
        goto max_err_out;
    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
    old_data_size = mftbmp_ni->allocated_size;
    ntfs_debug("Status of mftbmp before extension: allocated_size 0x%llx, "
            "data_size 0x%llx, initialized_size 0x%llx.",
            (long long)old_data_size,
            (long long)i_size_read(vol->mftbmp_ino),
            (long long)old_data_initialized);
    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
    if (old_data_initialized + 8 > old_data_size) {
        /* Need to extend bitmap by one more cluster. */
        ntfs_debug("mftbmp: initialized_size + 8 > allocated_size.");
        err = ntfs_mft_bitmap_extend_allocation_nolock(vol);
        if (unlikely(err)) {
            up_write(&vol->mftbmp_lock);
            goto err_out;
        }
#ifdef DEBUG
        read_lock_irqsave(&mftbmp_ni->size_lock, flags);
        ntfs_debug("Status of mftbmp after allocation extension: "
                "allocated_size 0x%llx, data_size 0x%llx, "
                "initialized_size 0x%llx.",
                (long long)mftbmp_ni->allocated_size,
                (long long)i_size_read(vol->mftbmp_ino),
                (long long)mftbmp_ni->initialized_size);
        read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
#endif /* DEBUG */
    }
    /*
     * We now have sufficient allocated space, extend the initialized_size
     * as well as the data_size if necessary and fill the new space with
     * zeroes.
     */
    err = ntfs_mft_bitmap_extend_initialized_nolock(vol);
    if (unlikely(err)) {
        up_write(&vol->mftbmp_lock);
        goto err_out;
    }
#ifdef DEBUG
    read_lock_irqsave(&mftbmp_ni->size_lock, flags);
    ntfs_debug("Status of mftbmp after initialized extension: "
            "allocated_size 0x%llx, data_size 0x%llx, "
            "initialized_size 0x%llx.",
            (long long)mftbmp_ni->allocated_size,
            (long long)i_size_read(vol->mftbmp_ino),
            (long long)mftbmp_ni->initialized_size);
    read_unlock_irqrestore(&mftbmp_ni->size_lock, flags);
#endif /* DEBUG */
    ntfs_debug("Found free record (#3), bit 0x%llx.", (long long)bit);
found_free_rec:
    /* @bit is the found free mft record, allocate it in the mft bitmap. */
    ntfs_debug("At found_free_rec.");
    err = ntfs_bitmap_set_bit(vol->mftbmp_ino, bit);
    if (unlikely(err)) {
        ntfs_error(vol->sb, "Failed to allocate bit in mft bitmap.");
        up_write(&vol->mftbmp_lock);
        goto err_out;
    }
    ntfs_debug("Set bit 0x%llx in mft bitmap.", (long long)bit);
have_alloc_rec:
    /*
     * The mft bitmap is now uptodate.  Deal with mft data attribute now.
     * Note, we keep hold of the mft bitmap lock for writing until all
     * modifications to the mft data attribute are complete, too, as they
     * will impact decisions for mft bitmap and mft record allocation done
     * by a parallel allocation and if the lock is not maintained a
     * parallel allocation could allocate the same mft record as this one.
     */
    ll = (bit + 1) << vol->mft_record_size_bits;
    read_lock_irqsave(&mft_ni->size_lock, flags);
    old_data_initialized = mft_ni->initialized_size;
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    if (ll <= old_data_initialized) {
        ntfs_debug("Allocated mft record already initialized.");
        goto mft_rec_already_initialized;
    }
    ntfs_debug("Initializing allocated mft record.");
    /*
     * The mft record is outside the initialized data.  Extend the mft data
     * attribute until it covers the allocated record.  The loop is only
     * actually traversed more than once when a freshly formatted volume is
     * first written to so it optimizes away nicely in the common case.
     */
    read_lock_irqsave(&mft_ni->size_lock, flags);
    ntfs_debug("Status of mft data before extension: "
            "allocated_size 0x%llx, data_size 0x%llx, "
            "initialized_size 0x%llx.",
            (long long)mft_ni->allocated_size,
            (long long)i_size_read(vol->mft_ino),
            (long long)mft_ni->initialized_size);
    while (ll > mft_ni->allocated_size) {
        read_unlock_irqrestore(&mft_ni->size_lock, flags);
        err = ntfs_mft_data_extend_allocation_nolock(vol);
        if (unlikely(err)) {
            ntfs_error(vol->sb, "Failed to extend mft data "
                    "allocation.");
            goto undo_mftbmp_alloc_nolock;
        }
        read_lock_irqsave(&mft_ni->size_lock, flags);
        ntfs_debug("Status of mft data after allocation extension: "
                "allocated_size 0x%llx, data_size 0x%llx, "
                "initialized_size 0x%llx.",
                (long long)mft_ni->allocated_size,
                (long long)i_size_read(vol->mft_ino),
                (long long)mft_ni->initialized_size);
    }
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    /*
     * Extend mft data initialized size (and data size of course) to reach
     * the allocated mft record, formatting the mft records allong the way.
     * Note: We only modify the ntfs_inode structure as that is all that is
     * needed by ntfs_mft_record_format().  We will update the attribute
     * record itself in one fell swoop later on.
     */
    write_lock_irqsave(&mft_ni->size_lock, flags);
    old_data_initialized = mft_ni->initialized_size;
    old_data_size = vol->mft_ino->i_size;
    while (ll > mft_ni->initialized_size) {
        s64 new_initialized_size, mft_no;
        
        new_initialized_size = mft_ni->initialized_size +
                vol->mft_record_size;
        mft_no = mft_ni->initialized_size >> vol->mft_record_size_bits;
        if (new_initialized_size > i_size_read(vol->mft_ino))
            i_size_write(vol->mft_ino, new_initialized_size);
        write_unlock_irqrestore(&mft_ni->size_lock, flags);
        ntfs_debug("Initializing mft record 0x%llx.",
                (long long)mft_no);
        err = ntfs_mft_record_format(vol, mft_no);
        if (unlikely(err)) {
            ntfs_error(vol->sb, "Failed to format mft record.");
            goto undo_data_init;
        }
        write_lock_irqsave(&mft_ni->size_lock, flags);
        mft_ni->initialized_size = new_initialized_size;
    }
    write_unlock_irqrestore(&mft_ni->size_lock, flags);
    record_formatted = true;
    /* Update the mft data attribute record to reflect the new sizes. */
    m = map_mft_record(mft_ni);
    if (IS_ERR(m)) {
        ntfs_error(vol->sb, "Failed to map mft record.");
        err = PTR_ERR(m);
        goto undo_data_init;
    }
    ctx = ntfs_attr_get_search_ctx(mft_ni, m);
    if (unlikely(!ctx)) {
        ntfs_error(vol->sb, "Failed to get search context.");
        err = -ENOMEM;
        unmap_mft_record(mft_ni);
        goto undo_data_init;
    }
    err = ntfs_attr_lookup(mft_ni->type, mft_ni->name, mft_ni->name_len,
            CASE_SENSITIVE, 0, NULL, 0, ctx);
    if (unlikely(err)) {
        ntfs_error(vol->sb, "Failed to find first attribute extent of "
                "mft data attribute.");
        ntfs_attr_put_search_ctx(ctx);
        unmap_mft_record(mft_ni);
        goto undo_data_init;
    }
    a = ctx->attr;
    read_lock_irqsave(&mft_ni->size_lock, flags);
    a->data.non_resident.initialized_size =
            cpu_to_sle64(mft_ni->initialized_size);
    a->data.non_resident.data_size =
            cpu_to_sle64(i_size_read(vol->mft_ino));
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
    /* Ensure the changes make it to disk. */
    flush_dcache_mft_record_page(ctx->ntfs_ino);
    mark_mft_record_dirty(ctx->ntfs_ino);
    ntfs_attr_put_search_ctx(ctx);
    unmap_mft_record(mft_ni);
    read_lock_irqsave(&mft_ni->size_lock, flags);
    ntfs_debug("Status of mft data after mft record initialization: "
            "allocated_size 0x%llx, data_size 0x%llx, "
            "initialized_size 0x%llx.",
            (long long)mft_ni->allocated_size,
            (long long)i_size_read(vol->mft_ino),
            (long long)mft_ni->initialized_size);
    BUG_ON(i_size_read(vol->mft_ino) > mft_ni->allocated_size);
    BUG_ON(mft_ni->initialized_size > i_size_read(vol->mft_ino));
    read_unlock_irqrestore(&mft_ni->size_lock, flags);
mft_rec_already_initialized:
    /*
     * We can finally drop the mft bitmap lock as the mft data attribute
     * has been fully updated.  The only disparity left is that the
     * allocated mft record still needs to be marked as in use to match the
     * set bit in the mft bitmap but this is actually not a problem since
     * this mft record is not referenced from anywhere yet and the fact
     * that it is allocated in the mft bitmap means that no-one will try to
     * allocate it either.
     */
    up_write(&vol->mftbmp_lock);
    /*
     * We now have allocated and initialized the mft record.  Calculate the
     * index of and the offset within the page cache page the record is in.
     */
    index = bit << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT;
    ofs = (bit << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK;
    /* Read, map, and pin the page containing the mft record. */
    page = ntfs_map_page(vol->mft_ino->i_mapping, index);
    if (IS_ERR(page)) {
        ntfs_error(vol->sb, "Failed to map page containing allocated "
                "mft record 0x%llx.", (long long)bit);
        err = PTR_ERR(page);
        goto undo_mftbmp_alloc;
    }
    lock_page(page);
    BUG_ON(!PageUptodate(page));
    ClearPageUptodate(page);
    m = (MFT_RECORD*)((u8*)page_address(page) + ofs);
    /* If we just formatted the mft record no need to do it again. */
    if (!record_formatted) {
        /* Sanity check that the mft record is really not in use. */
        if (ntfs_is_file_record(m->magic) &&
                (m->flags & MFT_RECORD_IN_USE)) {
            ntfs_error(vol->sb, "Mft record 0x%llx was marked "
                    "free in mft bitmap but is marked "
                    "used itself.  Corrupt filesystem.  "
                    "Unmount and run chkdsk.",
                    (long long)bit);
            err = -EIO;
            SetPageUptodate(page);
            unlock_page(page);
            ntfs_unmap_page(page);
            NVolSetErrors(vol);
            goto undo_mftbmp_alloc;
        }
        /*
         * We need to (re-)format the mft record, preserving the
         * sequence number if it is not zero as well as the update
         * sequence number if it is not zero or -1 (0xffff).  This
         * means we do not need to care whether or not something went
         * wrong with the previous mft record.
         */
        seq_no = m->sequence_number;
        usn = *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs));
        err = ntfs_mft_record_layout(vol, bit, m);
        if (unlikely(err)) {
            ntfs_error(vol->sb, "Failed to layout allocated mft "
                    "record 0x%llx.", (long long)bit);
            SetPageUptodate(page);
            unlock_page(page);
            ntfs_unmap_page(page);
            goto undo_mftbmp_alloc;
        }
        if (seq_no)
            m->sequence_number = seq_no;
        if (usn && le16_to_cpu(usn) != 0xffff)
            *(le16*)((u8*)m + le16_to_cpu(m->usa_ofs)) = usn;
    }
    /* Set the mft record itself in use. */
    m->flags |= MFT_RECORD_IN_USE;
    if (S_ISDIR(mode))
        m->flags |= MFT_RECORD_IS_DIRECTORY;
    flush_dcache_page(page);
    SetPageUptodate(page);
    if (base_ni) {
        MFT_RECORD *m_tmp;

        /*
         * Setup the base mft record in the extent mft record.  This
         * completes initialization of the allocated extent mft record
         * and we can simply use it with map_extent_mft_record().
         */
        m->base_mft_record = MK_LE_MREF(base_ni->mft_no,
                base_ni->seq_no);
        /*
         * Allocate an extent inode structure for the new mft record,
         * attach it to the base inode @base_ni and map, pin, and lock
         * its, i.e. the allocated, mft record.
         */
        m_tmp = map_extent_mft_record(base_ni, bit, &ni);
        if (IS_ERR(m_tmp)) {
            ntfs_error(vol->sb, "Failed to map allocated extent "
                    "mft record 0x%llx.", (long long)bit);
            err = PTR_ERR(m_tmp);
            /* Set the mft record itself not in use. */
            m->flags &= cpu_to_le16(
                    ~le16_to_cpu(MFT_RECORD_IN_USE));
            flush_dcache_page(page);
            /* Make sure the mft record is written out to disk. */
            mark_ntfs_record_dirty(page, ofs);
            unlock_page(page);
            ntfs_unmap_page(page);
            goto undo_mftbmp_alloc;
        }
        BUG_ON(m != m_tmp);
        /*
         * Make sure the allocated mft record is written out to disk.
         * No need to set the inode dirty because the caller is going
         * to do that anyway after finishing with the new extent mft
         * record (e.g. at a minimum a new attribute will be added to
         * the mft record.
         */
        mark_ntfs_record_dirty(page, ofs);
        unlock_page(page);
        /*
         * Need to unmap the page since map_extent_mft_record() mapped
         * it as well so we have it mapped twice at the moment.
         */
        ntfs_unmap_page(page);
    } else {
        /*
         * Allocate a new VFS inode and set it up.  NOTE: @vi->i_nlink
         * is set to 1 but the mft record->link_count is 0.  The caller
         * needs to bear this in mind.
         */
        vi = new_inode(vol->sb);
        if (unlikely(!vi)) {
            err = -ENOMEM;
            /* Set the mft record itself not in use. */
            m->flags &= cpu_to_le16(
                    ~le16_to_cpu(MFT_RECORD_IN_USE));
            flush_dcache_page(page);
            /* Make sure the mft record is written out to disk. */
            mark_ntfs_record_dirty(page, ofs);
            unlock_page(page);
            ntfs_unmap_page(page);
            goto undo_mftbmp_alloc;
        }
        vi->i_ino = bit;
        /*
         * This is for checking whether an inode has changed w.r.t. a
         * file so that the file can be updated if necessary (compare
         * with f_version).
         */
        vi->i_version = 1;

        /* The owner and group come from the ntfs volume. */
        vi->i_uid = vol->uid;
        vi->i_gid = vol->gid;

        /* Initialize the ntfs specific part of @vi. */
        ntfs_init_big_inode(vi);
        ni = NTFS_I(vi);
        /*
         * Set the appropriate mode, attribute type, and name.  For
         * directories, also setup the index values to the defaults.
         */
        if (S_ISDIR(mode)) {
            vi->i_mode = S_IFDIR | S_IRWXUGO;
            vi->i_mode &= ~vol->dmask;

            NInoSetMstProtected(ni);
            ni->type = AT_INDEX_ALLOCATION;
            ni->name = I30;
            ni->name_len = 4;

            ni->itype.index.block_size = 4096;
            ni->itype.index.block_size_bits = ntfs_ffs(4096) - 1;
            ni->itype.index.collation_rule = COLLATION_FILE_NAME;
            if (vol->cluster_size <= ni->itype.index.block_size) {
                ni->itype.index.vcn_size = vol->cluster_size;
                ni->itype.index.vcn_size_bits =
                        vol->cluster_size_bits;
            } else {
                ni->itype.index.vcn_size = vol->sector_size;
                ni->itype.index.vcn_size_bits =
                        vol->sector_size_bits;
            }
        } else {
            vi->i_mode = S_IFREG | S_IRWXUGO;
            vi->i_mode &= ~vol->fmask;

            ni->type = AT_DATA;
            ni->name = NULL;
            ni->name_len = 0;
        }
        if (IS_RDONLY(vi))
            vi->i_mode &= ~S_IWUGO;

        /* Set the inode times to the current time. */
        vi->i_atime = vi->i_mtime = vi->i_ctime =
            current_fs_time(vi->i_sb);
        /*
         * Set the file size to 0, the ntfs inode sizes are set to 0 by
         * the call to ntfs_init_big_inode() below.
         */
        vi->i_size = 0;
        vi->i_blocks = 0;

        /* Set the sequence number. */
        vi->i_generation = ni->seq_no = le16_to_cpu(m->sequence_number);
        /*
         * Manually map, pin, and lock the mft record as we already
         * have its page mapped and it is very easy to do.
         */
        atomic_inc(&ni->count);
        mutex_lock(&ni->mrec_lock);
        ni->page = page;
        ni->page_ofs = ofs;
        /*
         * Make sure the allocated mft record is written out to disk.
         * NOTE: We do not set the ntfs inode dirty because this would
         * fail in ntfs_write_inode() because the inode does not have a
         * standard information attribute yet.  Also, there is no need
         * to set the inode dirty because the caller is going to do
         * that anyway after finishing with the new mft record (e.g. at
         * a minimum some new attributes will be added to the mft
         * record.
         */
        mark_ntfs_record_dirty(page, ofs);
        unlock_page(page);

        /* Add the inode to the inode hash for the superblock. */
        insert_inode_hash(vi);

        /* Update the default mft allocation position. */
        vol->mft_data_pos = bit + 1;
    }
    /*
     * Return the opened, allocated inode of the allocated mft record as
     * well as the mapped, pinned, and locked mft record.
     */
    ntfs_debug("Returning opened, allocated %sinode 0x%llx.",
            base_ni ? "extent " : "", (long long)bit);
    *mrec = m;
    return ni;
undo_data_init:
    write_lock_irqsave(&mft_ni->size_lock, flags);
    mft_ni->initialized_size = old_data_initialized;
    i_size_write(vol->mft_ino, old_data_size);
    write_unlock_irqrestore(&mft_ni->size_lock, flags);
    goto undo_mftbmp_alloc_nolock;
undo_mftbmp_alloc:
    down_write(&vol->mftbmp_lock);
undo_mftbmp_alloc_nolock:
    if (ntfs_bitmap_clear_bit(vol->mftbmp_ino, bit)) {
        ntfs_error(vol->sb, "Failed to clear bit in mft bitmap.%s", es);
        NVolSetErrors(vol);
    }
    up_write(&vol->mftbmp_lock);
err_out:
    return ERR_PTR(err);
max_err_out:
    ntfs_warning(vol->sb, "Cannot allocate mft record because the maximum "
            "number of inodes (2^32) has already been reached.");
    up_write(&vol->mftbmp_lock);
    return ERR_PTR(-ENOSPC);
}

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 */