NTFS: Add fs/ntfs/attrib.[hc]::ntfs_attr_extend_allocation(), a function to

      extend the allocation of an attributes.  Optionally, the data size,
      but not the initialized size can be extended, too.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

3 files changed, 640 insertions, 0 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 045beda82942..6c5bdfbb7bbf 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -47,6 +47,9 @@ ToDo/Notes:
           which is zero for a resident attribute but should no longer be zero
           once the attribute is non-resident as it then has real clusters
           allocated.
+        - Add fs/ntfs/attrib.[hc]::ntfs_attr_extend_allocation(), a function to
+          extend the allocation of an attributes.  Optionally, the data size,
+          but not the initialized size can be extended, too.
 
 2.1.24 - Lots of bug fixes and support more clean journal states.
 
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 8821e2d088b7..bc25e88ad468 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -1835,6 +1835,640 @@ page_err_out:
 }
 
 /**
+ * ntfs_attr_extend_allocation - extend the allocated space of an attribute
+ * @ni:                 ntfs inode of the attribute whose allocation to extend
+ * @new_alloc_size:     new size in bytes to which to extend the allocation to
+ * @new_data_size:      new size in bytes to which to extend the data to
+ * @data_start:         beginning of region which is required to be non-sparse
+ *
+ * Extend the allocated space of an attribute described by the ntfs inode @ni
+ * to @new_alloc_size bytes.  If @data_start is -1, the whole extension may be
+ * implemented as a hole in the file (as long as both the volume and the ntfs
+ * inode @ni have sparse support enabled).  If @data_start is >= 0, then the
+ * region between the old allocated size and @data_start - 1 may be made sparse
+ * but the regions between @data_start and @new_alloc_size must be backed by
+ * actual clusters.
+ *
+ * If @new_data_size is -1, it is ignored.  If it is >= 0, then the data size
+ * of the attribute is extended to @new_data_size.  Note that the i_size of the
+ * vfs inode is not updated.  Only the data size in the base attribute record
+ * is updated.  The caller has to update i_size separately if this is required.
+ * WARNING: It is a BUG() for @new_data_size to be smaller than the old data
+ * size as well as for @new_data_size to be greater than @new_alloc_size.
+ *
+ * For resident attributes this involves resizing the attribute record and if
+ * necessary moving it and/or other attributes into extent mft records and/or
+ * converting the attribute to a non-resident attribute which in turn involves
+ * extending the allocation of a non-resident attribute as described below.
+ *
+ * For non-resident attributes this involves allocating clusters in the data
+ * zone on the volume (except for regions that are being made sparse) and
+ * extending the run list to describe the allocated clusters as well as
+ * updating the mapping pairs array of the attribute.  This in turn involves
+ * resizing the attribute record and if necessary moving it and/or other
+ * attributes into extent mft records and/or splitting the attribute record
+ * into multiple extent attribute records.
+ *
+ * Also, the attribute list attribute is updated if present and in some of the
+ * above cases (the ones where extent mft records/attributes come into play),
+ * an attribute list attribute is created if not already present.
+ *
+ * Return the new allocated size on success and -errno on error.  In the case
+ * that an error is encountered but a partial extension at least up to
+ * @data_start (if present) is possible, the allocation is partially extended
+ * and this is returned.  This means the caller must check the returned size to
+ * determine if the extension was partial.  If @data_start is -1 then partial
+ * allocations are not performed.
+ *
+ * WARNING: Do not call ntfs_attr_extend_allocation() for $MFT/$DATA.
+ *
+ * Locking: This function takes the runlist lock of @ni for writing as well as
+ * locking the mft record of the base ntfs inode.  These locks are maintained
+ * throughout execution of the function.  These locks are required so that the
+ * attribute can be resized safely and so that it can for example be converted
+ * from resident to non-resident safely.
+ *
+ * TODO: At present attribute list attribute handling is not implemented.
+ *
+ * TODO: At present it is not safe to call this function for anything other
+ * than the $DATA attribute(s) of an uncompressed and unencrypted file.
+ */
+s64 ntfs_attr_extend_allocation(ntfs_inode *ni, s64 new_alloc_size,
+                const s64 new_data_size, const s64 data_start)
+{
+        VCN vcn;
+        s64 ll, allocated_size, start = data_start;
+        struct inode *vi = VFS_I(ni);
+        ntfs_volume *vol = ni->vol;
+        ntfs_inode *base_ni;
+        MFT_RECORD *m;
+        ATTR_RECORD *a;
+        ntfs_attr_search_ctx *ctx;
+        runlist_element *rl, *rl2;
+        unsigned long flags;
+        int err, mp_size;
+        u32 attr_len = 0; /* Silence stupid gcc warning. */
+        BOOL mp_rebuilt;
+
+#ifdef NTFS_DEBUG
+        read_lock_irqsave(&ni->size_lock, flags);
+        allocated_size = ni->allocated_size;
+        read_unlock_irqrestore(&ni->size_lock, flags);
+        ntfs_debug("Entering for i_ino 0x%lx, attribute type 0x%x, "
+                        "old_allocated_size 0x%llx, "
+                        "new_allocated_size 0x%llx, new_data_size 0x%llx, "
+                        "data_start 0x%llx.", vi->i_ino,
+                        (unsigned)le32_to_cpu(ni->type),
+                        (unsigned long long)allocated_size,
+                        (unsigned long long)new_alloc_size,
+                        (unsigned long long)new_data_size,
+                        (unsigned long long)start);
+#endif
+retry_extend:
+        /*
+         * For non-resident attributes, @start and @new_size need to be aligned
+         * to cluster boundaries for allocation purposes.
+         */
+        if (NInoNonResident(ni)) {
+                if (start > 0)
+                        start &= ~(s64)vol->cluster_size_mask;
+                new_alloc_size = (new_alloc_size + vol->cluster_size - 1) &
+                                ~(s64)vol->cluster_size_mask;
+        }
+        BUG_ON(new_data_size >= 0 && new_data_size > new_alloc_size);
+        /* Check if new size is allowed in $AttrDef. */
+        err = ntfs_attr_size_bounds_check(vol, ni->type, new_alloc_size);
+        if (unlikely(err)) {
+                /* Only emit errors when the write will fail completely. */
+                read_lock_irqsave(&ni->size_lock, flags);
+                allocated_size = ni->allocated_size;
+                read_unlock_irqrestore(&ni->size_lock, flags);
+                if (start < 0 || start >= allocated_size) {
+                        if (err == -ERANGE) {
+                                ntfs_error(vol->sb, "Cannot extend allocation "
+                                                "of inode 0x%lx, attribute "
+                                                "type 0x%x, because the new "
+                                                "allocation would exceed the "
+                                                "maximum allowed size for "
+                                                "this attribute type.",
+                                                vi->i_ino, (unsigned)
+                                                le32_to_cpu(ni->type));
+                        } else {
+                                ntfs_error(vol->sb, "Cannot extend allocation "
+                                                "of inode 0x%lx, attribute "
+                                                "type 0x%x, because this "
+                                                "attribute type is not "
+                                                "defined on the NTFS volume.  "
+                                                "Possible corruption!  You "
+                                                "should run chkdsk!",
+                                                vi->i_ino, (unsigned)
+                                                le32_to_cpu(ni->type));
+                        }
+                }
+                /* Translate error code to be POSIX conformant for write(2). */
+                if (err == -ERANGE)
+                        err = -EFBIG;
+                else
+                        err = -EIO;
+                return err;
+        }
+        if (!NInoAttr(ni))
+                base_ni = ni;
+        else
+                base_ni = ni->ext.base_ntfs_ino;
+        /*
+         * We will be modifying both the runlist (if non-resident) and the mft
+         * record so lock them both down.
+         */
+        down_write(&ni->runlist.lock);
+        m = map_mft_record(base_ni);
+        if (IS_ERR(m)) {
+                err = PTR_ERR(m);
+                m = NULL;
+                ctx = NULL;
+                goto err_out;
+        }
+        ctx = ntfs_attr_get_search_ctx(base_ni, m);
+        if (unlikely(!ctx)) {
+                err = -ENOMEM;
+                goto err_out;
+        }
+        read_lock_irqsave(&ni->size_lock, flags);
+        allocated_size = ni->allocated_size;
+        read_unlock_irqrestore(&ni->size_lock, flags);
+        /*
+         * If non-resident, seek to the last extent.  If resident, there is
+         * only one extent, so seek to that.
+         */
+        vcn = NInoNonResident(ni) ? allocated_size >> vol->cluster_size_bits :
+                        0;
+        /*
+         * Abort if someone did the work whilst we waited for the locks.  If we
+         * just converted the attribute from resident to non-resident it is
+         * likely that exactly this has happened already.  We cannot quite
+         * abort if we need to update the data size.
+         */
+        if (unlikely(new_alloc_size <= allocated_size)) {
+                ntfs_debug("Allocated size already exceeds requested size.");
+                new_alloc_size = allocated_size;
+                if (new_data_size < 0)
+                        goto done;
+                /*
+                 * We want the first attribute extent so that we can update the
+                 * data size.
+                 */
+                vcn = 0;
+        }
+        err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                        CASE_SENSITIVE, vcn, NULL, 0, ctx);
+        if (unlikely(err)) {
+                if (err == -ENOENT)
+                        err = -EIO;
+                goto err_out;
+        }
+        m = ctx->mrec;
+        a = ctx->attr;
+        /* Use goto to reduce indentation. */
+        if (a->non_resident)
+                goto do_non_resident_extend;
+        BUG_ON(NInoNonResident(ni));
+        /* The total length of the attribute value. */
+        attr_len = le32_to_cpu(a->data.resident.value_length);
+        /*
+         * Extend the attribute record to be able to store the new attribute
+         * size.  ntfs_attr_record_resize() will not do anything if the size is
+         * not changing.
+         */
+        if (new_alloc_size < vol->mft_record_size &&
+                        !ntfs_attr_record_resize(m, a,
+                        le16_to_cpu(a->data.resident.value_offset) +
+                        new_alloc_size)) {
+                /* The resize succeeded! */
+                write_lock_irqsave(&ni->size_lock, flags);
+                ni->allocated_size = le32_to_cpu(a->length) -
+                                le16_to_cpu(a->data.resident.value_offset);
+                write_unlock_irqrestore(&ni->size_lock, flags);
+                if (new_data_size >= 0) {
+                        BUG_ON(new_data_size < attr_len);
+                        a->data.resident.value_length =
+                                        cpu_to_le32((u32)new_data_size);
+                }
+                goto flush_done;
+        }
+        /*
+         * We have to drop all the locks so we can call
+         * ntfs_attr_make_non_resident().  This could be optimised by try-
+         * locking the first page cache page and only if that fails dropping
+         * the locks, locking the page, and redoing all the locking and
+         * lookups.  While this would be a huge optimisation, it is not worth
+         * it as this is definitely a slow code path.
+         */
+        ntfs_attr_put_search_ctx(ctx);
+        unmap_mft_record(base_ni);
+        up_write(&ni->runlist.lock);
+        /*
+         * Not enough space in the mft record, try to make the attribute
+         * non-resident and if successful restart the extension process.
+         */
+        err = ntfs_attr_make_non_resident(ni, attr_len);
+        if (likely(!err))
+                goto retry_extend;
+        /*
+         * Could not make non-resident.  If this is due to this not being
+         * permitted for this attribute type or there not being enough space,
+         * try to make other attributes non-resident.  Otherwise fail.
+         */
+        if (unlikely(err != -EPERM && err != -ENOSPC)) {
+                /* Only emit errors when the write will fail completely. */
+                read_lock_irqsave(&ni->size_lock, flags);
+                allocated_size = ni->allocated_size;
+                read_unlock_irqrestore(&ni->size_lock, flags);
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Cannot extend allocation of "
+                                        "inode 0x%lx, attribute type 0x%x, "
+                                        "because the conversion from resident "
+                                        "to non-resident attribute failed "
+                                        "with error code %i.", vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type), err);
+                if (err != -ENOMEM)
+                        err = -EIO;
+                goto conv_err_out;
+        }
+        /* TODO: Not implemented from here, abort. */
+        read_lock_irqsave(&ni->size_lock, flags);
+        allocated_size = ni->allocated_size;
+        read_unlock_irqrestore(&ni->size_lock, flags);
+        if (start < 0 || start >= allocated_size) {
+                if (err == -ENOSPC)
+                        ntfs_error(vol->sb, "Not enough space in the mft "
+                                        "record/on disk for the non-resident "
+                                        "attribute value.  This case is not "
+                                        "implemented yet.");
+                else /* if (err == -EPERM) */
+                        ntfs_error(vol->sb, "This attribute type may not be "
+                                        "non-resident.  This case is not "
+                                        "implemented yet.");
+        }
+        err = -EOPNOTSUPP;
+        goto conv_err_out;
+#if 0
+        // TODO: Attempt to make other attributes non-resident.
+        if (!err)
+                goto do_resident_extend;
+        /*
+         * Both the attribute list attribute and the standard information
+         * attribute must remain in the base inode.  Thus, if this is one of
+         * these attributes, we have to try to move other attributes out into
+         * extent mft records instead.
+         */
+        if (ni->type == AT_ATTRIBUTE_LIST ||
+                        ni->type == AT_STANDARD_INFORMATION) {
+                // TODO: Attempt to move other attributes into extent mft
+                // records.
+                err = -EOPNOTSUPP;
+                if (!err)
+                        goto do_resident_extend;
+                goto err_out;
+        }
+        // TODO: Attempt to move this attribute to an extent mft record, but
+        // only if it is not already the only attribute in an mft record in
+        // which case there would be nothing to gain.
+        err = -EOPNOTSUPP;
+        if (!err)
+                goto do_resident_extend;
+        /* There is nothing we can do to make enough space. )-: */
+        goto err_out;
+#endif
+do_non_resident_extend:
+        BUG_ON(!NInoNonResident(ni));
+        if (new_alloc_size == allocated_size) {
+                BUG_ON(vcn);
+                goto alloc_done;
+        }
+        /*
+         * If the data starts after the end of the old allocation, this is a
+         * $DATA attribute and sparse attributes are enabled on the volume and
+         * for this inode, then create a sparse region between the old
+         * allocated size and the start of the data.  Otherwise simply proceed
+         * with filling the whole space between the old allocated size and the
+         * new allocated size with clusters.
+         */
+        if ((start >= 0 && start <= allocated_size) || ni->type != AT_DATA ||
+                        !NVolSparseEnabled(vol) || NInoSparseDisabled(ni))
+                goto skip_sparse;
+        // TODO: This is not implemented yet.  We just fill in with real
+        // clusters for now...
+        ntfs_debug("Inserting holes is not-implemented yet.  Falling back to "
+                        "allocating real clusters instead.");
+skip_sparse:
+        rl = ni->runlist.rl;
+        if (likely(rl)) {
+                /* Seek to the end of the runlist. */
+                while (rl->length)
+                        rl++;
+        }
+        /* If this attribute extent is not mapped, map it now. */
+        if (unlikely(!rl || rl->lcn == LCN_RL_NOT_MAPPED ||
+                        (rl->lcn == LCN_ENOENT && rl > ni->runlist.rl &&
+                        (rl-1)->lcn == LCN_RL_NOT_MAPPED))) {
+                if (!rl && !allocated_size)
+                        goto first_alloc;
+                rl = ntfs_mapping_pairs_decompress(vol, a, ni->runlist.rl);
+                if (IS_ERR(rl)) {
+                        err = PTR_ERR(rl);
+                        if (start < 0 || start >= allocated_size)
+                                ntfs_error(vol->sb, "Cannot extend allocation "
+                                                "of inode 0x%lx, attribute "
+                                                "type 0x%x, because the "
+                                                "mapping of a runlist "
+                                                "fragment failed with error "
+                                                "code %i.", vi->i_ino,
+                                                (unsigned)le32_to_cpu(ni->type),
+                                                err);
+                        if (err != -ENOMEM)
+                                err = -EIO;
+                        goto err_out;
+                }
+                ni->runlist.rl = rl;
+                /* Seek to the end of the runlist. */
+                while (rl->length)
+                        rl++;
+        }
+        /*
+         * We now know the runlist of the last extent is mapped and @rl is at
+         * the end of the runlist.  We want to begin allocating clusters
+         * starting at the last allocated cluster to reduce fragmentation.  If
+         * there are no valid LCNs in the attribute we let the cluster
+         * allocator choose the starting cluster.
+         */
+        /* If the last LCN is a hole or simillar seek back to last real LCN. */
+        while (rl->lcn < 0 && rl > ni->runlist.rl)
+                rl--;
+first_alloc:
+        // FIXME: Need to implement partial allocations so at least part of the
+        // write can be performed when start >= 0.  (Needed for POSIX write(2)
+        // conformance.)
+        rl2 = ntfs_cluster_alloc(vol, allocated_size >> vol->cluster_size_bits,
+                        (new_alloc_size - allocated_size) >>
+                        vol->cluster_size_bits, (rl && (rl->lcn >= 0)) ?
+                        rl->lcn + rl->length : -1, DATA_ZONE, TRUE);
+        if (IS_ERR(rl2)) {
+                err = PTR_ERR(rl2);
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Cannot extend allocation of "
+                                        "inode 0x%lx, attribute type 0x%x, "
+                                        "because the allocation of clusters "
+                                        "failed with error code %i.", vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type), err);
+                if (err != -ENOMEM && err != -ENOSPC)
+                        err = -EIO;
+                goto err_out;
+        }
+        rl = ntfs_runlists_merge(ni->runlist.rl, rl2);
+        if (IS_ERR(rl)) {
+                err = PTR_ERR(rl);
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Cannot extend allocation of "
+                                        "inode 0x%lx, attribute type 0x%x, "
+                                        "because the runlist merge failed "
+                                        "with error code %i.", vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type), err);
+                if (err != -ENOMEM)
+                        err = -EIO;
+                if (ntfs_cluster_free_from_rl(vol, rl2)) {
+                        ntfs_error(vol->sb, "Failed to release allocated "
+                                        "cluster(s) in error code path.  Run "
+                                        "chkdsk to recover the lost "
+                                        "cluster(s).");
+                        NVolSetErrors(vol);
+                }
+                ntfs_free(rl2);
+                goto err_out;
+        }
+        ni->runlist.rl = rl;
+        ntfs_debug("Allocated 0x%llx clusters.", (long long)(new_alloc_size -
+                        allocated_size) >> vol->cluster_size_bits);
+        /* Find the runlist element with which the attribute extent starts. */
+        ll = sle64_to_cpu(a->data.non_resident.lowest_vcn);
+        rl2 = ntfs_rl_find_vcn_nolock(rl, ll);
+        BUG_ON(!rl2);
+        BUG_ON(!rl2->length);
+        BUG_ON(rl2->lcn < LCN_HOLE);
+        mp_rebuilt = FALSE;
+        /* 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)) {
+                err = mp_size;
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Cannot extend allocation of "
+                                        "inode 0x%lx, attribute type 0x%x, "
+                                        "because determining the size for the "
+                                        "mapping pairs failed with error code "
+                                        "%i.", vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type), err);
+                err = -EIO;
+                goto undo_alloc;
+        }
+        /* Extend the attribute record to fit the bigger mapping pairs array. */
+        attr_len = le32_to_cpu(a->length);
+        err = ntfs_attr_record_resize(m, a, mp_size +
+                        le16_to_cpu(a->data.non_resident.mapping_pairs_offset));
+        if (unlikely(err)) {
+                BUG_ON(err != -ENOSPC);
+                // TODO: Deal with this by moving this extent to a new mft
+                // record or by starting a new extent in a new mft record,
+                // possibly by extending this extent partially and filling it
+                // and creating a new extent for the remainder, or by making
+                // other attributes non-resident and/or by moving other
+                // attributes out of this mft record.
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Not enough space in the mft "
+                                        "record for the extended attribute "
+                                        "record.  This case is not "
+                                        "implemented yet.");
+                err = -EOPNOTSUPP;
+                goto undo_alloc;
+        }
+        mp_rebuilt = TRUE;
+        /* Generate the mapping pairs array directly into the attr record. */
+        err = 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(err)) {
+                if (start < 0 || start >= allocated_size)
+                        ntfs_error(vol->sb, "Cannot extend allocation of "
+                                        "inode 0x%lx, attribute type 0x%x, "
+                                        "because building the mapping pairs "
+                                        "failed with error code %i.", vi->i_ino,
+                                        (unsigned)le32_to_cpu(ni->type), err);
+                err = -EIO;
+                goto undo_alloc;
+        }
+        /* Update the highest_vcn. */
+        a->data.non_resident.highest_vcn = cpu_to_sle64((new_alloc_size >>
+                        vol->cluster_size_bits) - 1);
+        /*
+         * We now have extended the allocated size of the attribute.  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);
+                err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len,
+                                CASE_SENSITIVE, 0, NULL, 0, ctx);
+                if (unlikely(err))
+                        goto restore_undo_alloc;
+                /* @m is not used any more so no need to set it. */
+                a = ctx->attr;
+        }
+        write_lock_irqsave(&ni->size_lock, flags);
+        ni->allocated_size = new_alloc_size;
+        a->data.non_resident.allocated_size = cpu_to_sle64(new_alloc_size);
+        /*
+         * FIXME: This would fail if @ni is a directory, $MFT, or an index,
+         * since those can have sparse/compressed set.  For example can be
+         * set compressed even though it is not compressed itself and in that
+         * case the bit means that files are to be created compressed in the
+         * directory...  At present this is ok as this code is only called for
+         * regular files, and only for their $DATA attribute(s).
+         * FIXME: The calculation is wrong if we created a hole above.  For now
+         * it does not matter as we never create holes.
+         */
+        if (NInoSparse(ni) || NInoCompressed(ni)) {
+                ni->itype.compressed.size += new_alloc_size - allocated_size;
+                a->data.non_resident.compressed_size =
+                                cpu_to_sle64(ni->itype.compressed.size);
+                vi->i_blocks = ni->itype.compressed.size >> 9;
+        } else
+                vi->i_blocks = new_alloc_size >> 9;
+        write_unlock_irqrestore(&ni->size_lock, flags);
+alloc_done:
+        if (new_data_size >= 0) {
+                BUG_ON(new_data_size <
+                                sle64_to_cpu(a->data.non_resident.data_size));
+                a->data.non_resident.data_size = cpu_to_sle64(new_data_size);
+        }
+flush_done:
+        /* Ensure the changes make it to disk. */
+        flush_dcache_mft_record_page(ctx->ntfs_ino);
+        mark_mft_record_dirty(ctx->ntfs_ino);
+done:
+        ntfs_attr_put_search_ctx(ctx);
+        unmap_mft_record(base_ni);
+        up_write(&ni->runlist.lock);
+        ntfs_debug("Done, new_allocated_size 0x%llx.",
+                        (unsigned long long)new_alloc_size);
+        return new_alloc_size;
+restore_undo_alloc:
+        if (start < 0 || start >= allocated_size)
+                ntfs_error(vol->sb, "Cannot complete extension of allocation "
+                                "of inode 0x%lx, attribute type 0x%x, because "
+                                "lookup of first attribute extent failed with "
+                                "error code %i.", vi->i_ino,
+                                (unsigned)le32_to_cpu(ni->type), err);
+        if (err == -ENOENT)
+                err = -EIO;
+        ntfs_attr_reinit_search_ctx(ctx);
+        if (ntfs_attr_lookup(ni->type, ni->name, ni->name_len, CASE_SENSITIVE,
+                        allocated_size >> vol->cluster_size_bits, NULL, 0,
+                        ctx)) {
+                ntfs_error(vol->sb, "Failed to find last attribute extent of "
+                                "attribute in error code path.  Run chkdsk to "
+                                "recover.");
+                write_lock_irqsave(&ni->size_lock, flags);
+                ni->allocated_size = new_alloc_size;
+                /*
+                 * FIXME: This would fail if @ni is a directory...  See above.
+                 * FIXME: The calculation is wrong if we created a hole above.
+                 * For now it does not matter as we never create holes.
+                 */
+                if (NInoSparse(ni) || NInoCompressed(ni)) {
+                        ni->itype.compressed.size += new_alloc_size -
+                                        allocated_size;
+                        vi->i_blocks = ni->itype.compressed.size >> 9;
+                } else
+                        vi->i_blocks = new_alloc_size >> 9;
+                write_unlock_irqrestore(&ni->size_lock, flags);
+                ntfs_attr_put_search_ctx(ctx);
+                unmap_mft_record(base_ni);
+                up_write(&ni->runlist.lock);
+                /*
+                 * The only thing that is now wrong is the allocated size of the
+                 * base attribute extent which chkdsk should be able to fix.
+                 */
+                NVolSetErrors(vol);
+                return err;
+        }
+        ctx->attr->data.non_resident.highest_vcn = cpu_to_sle64(
+                        (allocated_size >> vol->cluster_size_bits) - 1);
+undo_alloc:
+        ll = allocated_size >> vol->cluster_size_bits;
+        if (ntfs_cluster_free(ni, ll, -1, ctx) < 0) {
+                ntfs_error(vol->sb, "Failed to release allocated cluster(s) "
+                                "in error code path.  Run chkdsk to recover "
+                                "the lost cluster(s).");
+                NVolSetErrors(vol);
+        }
+        m = ctx->mrec;
+        a = ctx->attr;
+        /*
+         * If the runlist truncation fails and/or the search context is no
+         * longer valid, we cannot resize the attribute record or build the
+         * mapping pairs array thus we mark the inode bad so that no access to
+         * the freed clusters can happen.
+         */
+        if (ntfs_rl_truncate_nolock(vol, &ni->runlist, ll) || IS_ERR(m)) {
+                ntfs_error(vol->sb, "Failed to %s in error code path.  Run "
+                                "chkdsk to recover.", IS_ERR(m) ?
+                                "restore attribute search context" :
+                                "truncate attribute runlist");
+                make_bad_inode(vi);
+                make_bad_inode(VFS_I(base_ni));
+                NVolSetErrors(vol);
+        } else if (mp_rebuilt) {
+                if (ntfs_attr_record_resize(m, a, attr_len)) {
+                        ntfs_error(vol->sb, "Failed to restore attribute "
+                                        "record in error code path.  Run "
+                                        "chkdsk to recover.");
+                        make_bad_inode(vi);
+                        make_bad_inode(VFS_I(base_ni));
+                        NVolSetErrors(vol);
+                } else /* if (success) */ {
+                        if (ntfs_mapping_pairs_build(vol, (u8*)a + le16_to_cpu(
+                                        a->data.non_resident.
+                                        mapping_pairs_offset), attr_len -
+                                        le16_to_cpu(a->data.non_resident.
+                                        mapping_pairs_offset), rl2, ll, -1,
+                                        NULL)) {
+                                ntfs_error(vol->sb, "Failed to restore "
+                                                "mapping pairs array in error "
+                                                "code path.  Run chkdsk to "
+                                                "recover.");
+                                make_bad_inode(vi);
+                                make_bad_inode(VFS_I(base_ni));
+                                NVolSetErrors(vol);
+                        }
+                        flush_dcache_mft_record_page(ctx->ntfs_ino);
+                        mark_mft_record_dirty(ctx->ntfs_ino);
+                }
+        }
+err_out:
+        if (ctx)
+                ntfs_attr_put_search_ctx(ctx);
+        if (m)
+                unmap_mft_record(base_ni);
+        up_write(&ni->runlist.lock);
+conv_err_out:
+        ntfs_debug("Failed.  Returning error code %i.", err);
+        return err;
+}
+
+/**
  * ntfs_attr_set - fill (a part of) an attribute with a byte
  * @ni:         ntfs inode describing the attribute to fill
  * @ofs:        offset inside the attribute at which to start to fill
diff --git a/fs/ntfs/attrib.h b/fs/ntfs/attrib.h
index a959af9cef12..9074886b44ba 100644
--- a/fs/ntfs/attrib.h
+++ b/fs/ntfs/attrib.h
@@ -105,6 +105,9 @@ extern int ntfs_resident_attr_value_resize(MFT_RECORD *m, ATTR_RECORD *a,
 
 extern int ntfs_attr_make_non_resident(ntfs_inode *ni, const u32 data_size);
 
+extern s64 ntfs_attr_extend_allocation(ntfs_inode *ni, s64 new_alloc_size,
+                const s64 new_data_size, const s64 data_start);
+
 extern int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt,
                 const u8 val);