tests/qemu-iotests/244 - third_party/qemu - Git at Google

 #!/usr/bin/env bash
 # group: rw auto quick
 #
 # Test qcow2 with external data files
 #
 # Copyright (C) 2019 Red Hat, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation; either version 2 of the License, or
 # (at your option) any later version.
 #
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #

 # creator
 owner=kwolf@redhat.com

 seq=$(basename $0)
 echo "QA output created by $seq"

 status=1	# failure is the default!

 _cleanup()
 {
     _cleanup_test_img
     _rm_test_img "$TEST_IMG.data"
     _rm_test_img "$TEST_IMG.src"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15

 # get standard environment, filters and checks
 . ./common.rc
 . ./common.filter
 . ./common.qemu

 _supported_fmt qcow2
 _supported_proto file
 _supported_os Linux
 # External data files do not work with compat=0.10, and because we use
 # our own external data file, we cannot let the user specify one
 _unsupported_imgopts 'compat=0.10' data_file

 echo
 echo "=== Create and open image with external data file ==="
 echo

 echo "With data file name in the image:"
 _make_test_img -o "data_file=$TEST_IMG.data" 64M
 _check_test_img

 $QEMU_IO -c "open $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir

 echo
 echo "Data file required, but without data file name in the image:"
 $QEMU_IMG amend -odata_file= $TEST_IMG

 $QEMU_IO -c "open $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir

 echo
 echo "Setting data-file for an image with internal data:"
 _make_test_img 64M

 $QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir
 $QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 | _filter_qemu_io | _filter_testdir

 echo
 echo "=== Conflicting features ==="
 echo

 echo "Convert to compressed target with data file:"
 TEST_IMG="$TEST_IMG.src" _make_test_img 64M

 $QEMU_IO -c 'write -P 0x11 0 1M' \
          -f $IMGFMT "$TEST_IMG.src" |
          _filter_qemu_io

 $QEMU_IMG convert -f $IMGFMT -O $IMGFMT -c -odata_file="$TEST_IMG.data" \
     "$TEST_IMG.src" "$TEST_IMG"

 echo
 echo "Convert uncompressed, then write compressed data manually:"
 $QEMU_IMG convert -f $IMGFMT -O $IMGFMT -odata_file="$TEST_IMG.data" \
     "$TEST_IMG.src" "$TEST_IMG"
 $QEMU_IMG compare "$TEST_IMG.src" "$TEST_IMG"

 $QEMU_IO -c 'write -c -P 0x22 0 1M' \
          -f $IMGFMT "$TEST_IMG" |
          _filter_qemu_io
 _check_test_img

 echo
 echo "Take an internal snapshot:"

 $QEMU_IMG snapshot -c test "$TEST_IMG"
 _check_test_img

 echo
 echo "=== Standalone image with external data file (efficient) ==="
 echo

 _make_test_img -o "data_file=$TEST_IMG.data" 64M

 echo -n "qcow2 file size before I/O: "
 du -b $TEST_IMG | cut -f1

 # Create image with the following layout
 # 0-1 MB: Unallocated
 # 1-2 MB: Written (pattern 0x11)
 # 2-3 MB: Discarded
 # 3-4 MB: Zero write over discarded space
 # 4-5 MB: Zero write over written space
 # 5-6 MB: Zero write over unallocated space

 echo
 $QEMU_IO -c 'write -P 0x11 1M 4M' \
          -c 'discard 2M 2M' \
          -c 'write -z 3M 3M' \
          -f $IMGFMT "$TEST_IMG" |
          _filter_qemu_io
 _check_test_img

 echo
 $QEMU_IMG map --output=json "$TEST_IMG"

 echo
 $QEMU_IO -c 'read -P 0 0 1M' \
          -c 'read -P 0x11 1M 1M' \
          -c 'read -P 0 2M 4M' \
          -f $IMGFMT "$TEST_IMG" |
          _filter_qemu_io

 # Zero clusters are only marked as such in the qcow2 metadata, but contain
 # stale data in the external data file
 echo
 $QEMU_IO -c 'read -P 0 0 1M' \
          -c 'read -P 0x11 1M 1M' \
          -c 'read -P 0x11 4M 1M' \
          -c 'read -P 0 5M 1M' \
          -f raw "$TEST_IMG.data" |
          _filter_qemu_io


 echo -n "qcow2 file size after I/O: "
 du -b $TEST_IMG | cut -f1

 echo
 echo "=== Standalone image with external data file (valid raw) ==="
 echo

 _make_test_img -o "data_file=$TEST_IMG.data,data_file_raw=on" 64M

 echo -n "qcow2 file size before I/O: "
 du -b $TEST_IMG | cut -f1

 echo
 $QEMU_IO -c 'write -P 0x11 1M 4M' \
          -c 'discard 2M 2M' \
          -c 'write -z 3M 3M' \
          -f $IMGFMT "$TEST_IMG" |
          _filter_qemu_io
 _check_test_img

 echo
 $QEMU_IMG map --output=json "$TEST_IMG"

 echo
 $QEMU_IO -c 'read -P 0 0 1M' \
          -c 'read -P 0x11 1M 1M' \
          -c 'read -P 0 2M 4M' \
          -f $IMGFMT "$TEST_IMG" |
          _filter_qemu_io

 # Discarded clusters are only marked as such in the qcow2 metadata, but
 # they can contain stale data in the external data file.  Instead, zero
 # clusters must be zeroed in the external data file too.
 echo
 $QEMU_IO -c 'read -P 0 0 1M' \
          -c 'read -P 0x11 1M 1M' \
          -c 'read -P 0 3M 3M' \
          -f raw "$TEST_IMG".data |
          _filter_qemu_io

 echo -n "qcow2 file size after I/O: "
 du -b $TEST_IMG | cut -f1

 echo
 echo "=== bdrv_co_block_status test for file and offset=0 ==="
 echo

 _make_test_img -o "data_file=$TEST_IMG.data" 64M

 $QEMU_IO -c 'write -P 0x11 0 1M' -f $IMGFMT "$TEST_IMG" | _filter_qemu_io
 $QEMU_IO -c 'read -P 0x11 0 1M' -f $IMGFMT "$TEST_IMG" | _filter_qemu_io
 $QEMU_IMG map --output=human "$TEST_IMG" | _filter_testdir
 $QEMU_IMG map --output=json "$TEST_IMG"

 echo
 echo "=== Copy offloading ==="
 echo

 # Make use of copy offloading if the test host can provide it
 _make_test_img -o "data_file=$TEST_IMG.data" 64M
 $QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
 $QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"

 # blkdebug doesn't support copy offloading, so this tests the error path
 $QEMU_IMG amend -f $IMGFMT -o "data_file=blkdebug::$TEST_IMG.data" "$TEST_IMG"
 $QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
 $QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"

 echo
 echo "=== Flushing should flush the data file ==="
 echo

 # We are going to flush a qcow2 file with a blkdebug node inserted
 # between the qcow2 node and its data file node.  The blkdebug node
 # will return an error for all flushes and so we if the data file is
 # flushed, we will see qemu-io return an error.

 # We need to write something or the flush will not do anything; we
 # also need -t writeback so the write is not done as a FUA write
 # (which would then fail thanks to the implicit flush)
 $QEMU_IO -c 'write 0 512' -c flush \
     -t writeback \
     "json:{
          'driver': 'qcow2',
          'file': {
              'driver': 'file',
              'filename': '$TEST_IMG'
          },
          'data-file': {
              'driver': 'blkdebug',
              'inject-error': [{
                  'event': 'none',
                  'iotype': 'flush'
              }],
              'image': {
                  'driver': 'file',
                  'filename': '$TEST_IMG.data'
              }
          }
      }" \
     | _filter_qemu_io

 result=${PIPESTATUS[0]}
 echo

 case $result in
     0)
         echo "ERROR: qemu-io succeeded, so the data file was not flushed"
         ;;
     1)
         echo "Success: qemu-io failed, so the data file was flushed"
         ;;
     *)
         echo "ERROR: qemu-io returned unknown exit code $result"
         ;;
 esac

 echo
 echo '=== Preallocation with data-file-raw ==='

 echo
 echo '--- Using a non-zeroed data file ---'

 # Using data-file-raw must enforce at least metadata preallocation so
 # that it does not matter whether one reads the raw file or the qcow2
 # file

 # Pre-create the data file, write some data.  Real-world use cases for
 # this are adding a qcow2 metadata file to a block device (i.e., using
 # the device as the data file) or adding qcow2 features to pre-existing
 # raw images (e.g. because the user now wants persistent dirty bitmaps).
 truncate -s 1M "$TEST_IMG.data"
 $QEMU_IO -f raw -c 'write -P 42 0 1M' "$TEST_IMG.data" | _filter_qemu_io

 # We cannot use qemu-img to create the qcow2 image, because it would
 # clear the data file.  Use the blockdev-create job instead, which will
 # only format the qcow2 image file.
 touch "$TEST_IMG"
 _launch_qemu \
     -blockdev file,node-name=data,filename="$TEST_IMG.data" \
     -blockdev file,node-name=meta,filename="$TEST_IMG"

 _send_qemu_cmd $QEMU_HANDLE '{ "execute": "qmp_capabilities" }' 'return'

 _send_qemu_cmd $QEMU_HANDLE \
     '{ "execute": "blockdev-create",
        "arguments": {
            "job-id": "create",
            "options": {
                "driver": "qcow2",
                "size": '"$((1 * 1024 * 1024))"',
                "file": "meta",
                "data-file": "data",
                "data-file-raw": true
            } } }' \
     '"status": "concluded"'

 _send_qemu_cmd $QEMU_HANDLE \
     '{ "execute": "job-dismiss", "arguments": { "id": "create" } }' \
     'return'

 _cleanup_qemu

 echo
 echo 'Comparing pattern:'

 # Reading from either the qcow2 file or the data file should return
 # the same result:
 $QEMU_IO -f raw -c 'read -P 42 0 1M' "$TEST_IMG.data" | _filter_qemu_io
 $QEMU_IO -f $IMGFMT -c 'read -P 42 0 1M' "$TEST_IMG" | _filter_qemu_io

 # For good measure
 $QEMU_IMG compare -f raw "$TEST_IMG.data" "$TEST_IMG"

 echo
 echo '--- Truncation (growing) ---'

 # Append some new data to the raw file, then resize the qcow2 image
 # accordingly and see whether the new data is visible.  Technically
 # that is not allowed, but it is reasonable behavior, so test it.
 truncate -s 2M "$TEST_IMG.data"
 $QEMU_IO -f raw -c 'write -P 84 1M 1M' "$TEST_IMG.data" | _filter_qemu_io

 $QEMU_IMG resize "$TEST_IMG" 2M

 echo
 echo 'Comparing pattern:'

 $QEMU_IO -f raw -c 'read -P 42 0 1M' -c 'read -P 84 1M 1M' "$TEST_IMG.data" \
     | _filter_qemu_io
 $QEMU_IO -f $IMGFMT -c 'read -P 42 0 1M' -c 'read -P 84 1M 1M' "$TEST_IMG" \
     | _filter_qemu_io

 $QEMU_IMG compare -f raw "$TEST_IMG.data" "$TEST_IMG"

 echo
 echo '--- Giving a backing file at runtime ---'

 # qcow2 files with data-file-raw cannot have backing files given by
 # their image header, but qemu will allow you to set a backing node at
 # runtime -- it should not have any effect, though (because reading
 # from the qcow2 node should return the same data as reading from the
 # raw node).

 _make_test_img -o "data_file=$TEST_IMG.data,data_file_raw=on" 1M
 TEST_IMG="$TEST_IMG.base" _make_test_img 1M

 # Write something that is not zero into the base image
 $QEMU_IO -c 'write -P 42 0 1M' "$TEST_IMG.base" | _filter_qemu_io

 echo
 echo 'Comparing qcow2 image and raw data file:'

 # $TEST_IMG and $TEST_IMG.data must show the same data at all times;
 # that is, the qcow2 node must not fall through to the backing image
 # at any point
 $QEMU_IMG compare --image-opts \
     "driver=raw,file.filename=$TEST_IMG.data"  \
     "file.filename=$TEST_IMG,backing.file.filename=$TEST_IMG.base"

 # success, all done
 echo "*** done"
 rm -f $seq.full
 status=0
	#!/usr/bin/env bash
	# group: rw auto quick
	#
	# Test qcow2 with external data files
	#
	# Copyright (C) 2019 Red Hat, Inc.
	#
	# This program is free software; you can redistribute it and/or modify
	# it under the terms of the GNU General Public License as published by
	# the Free Software Foundation; either version 2 of the License, or
	# (at your option) any later version.
	#
	# This program is distributed in the hope that it will be useful,
	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	# GNU General Public License for more details.
	#
	# You should have received a copy of the GNU General Public License
	# along with this program. If not, see <http://www.gnu.org/licenses/>.
	#

	# creator
	owner=kwolf@redhat.com

	seq=$(basename $0)
	echo "QA output created by $seq"

	status=1 # failure is the default!

	_cleanup()
	{
	_cleanup_test_img
	_rm_test_img "$TEST_IMG.data"
	_rm_test_img "$TEST_IMG.src"
	}
	trap "_cleanup; exit \$status" 0 1 2 3 15

	# get standard environment, filters and checks
	. ./common.rc
	. ./common.filter
	. ./common.qemu

	_supported_fmt qcow2
	_supported_proto file
	_supported_os Linux
	# External data files do not work with compat=0.10, and because we use
	# our own external data file, we cannot let the user specify one
	_unsupported_imgopts 'compat=0.10' data_file

	echo
	echo "=== Create and open image with external data file ==="
	echo

	echo "With data file name in the image:"
	_make_test_img -o "data_file=$TEST_IMG.data" 64M
	_check_test_img

	$QEMU_IO -c "open $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir
	$QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir
	$QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir

	echo
	echo "Data file required, but without data file name in the image:"
	$QEMU_IMG amend -odata_file= $TEST_IMG

	$QEMU_IO -c "open $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir
	$QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir
	$QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir

	echo
	echo "Setting data-file for an image with internal data:"
	_make_test_img 64M

	$QEMU_IO -c "open -odata-file.filename=$TEST_IMG.data $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir
	$QEMU_IO -c "open -odata-file.filename=inexistent $TEST_IMG" -c "read -P 0 0 64k" 2>&1 \| _filter_qemu_io \| _filter_testdir

	echo
	echo "=== Conflicting features ==="
	echo

	echo "Convert to compressed target with data file:"
	TEST_IMG="$TEST_IMG.src" _make_test_img 64M

	$QEMU_IO -c 'write -P 0x11 0 1M' \
	-f $IMGFMT "$TEST_IMG.src" \|
	_filter_qemu_io

	$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -c -odata_file="$TEST_IMG.data" \
	"$TEST_IMG.src" "$TEST_IMG"

	echo
	echo "Convert uncompressed, then write compressed data manually:"
	$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -odata_file="$TEST_IMG.data" \
	"$TEST_IMG.src" "$TEST_IMG"
	$QEMU_IMG compare "$TEST_IMG.src" "$TEST_IMG"

	$QEMU_IO -c 'write -c -P 0x22 0 1M' \
	-f $IMGFMT "$TEST_IMG" \|
	_filter_qemu_io
	_check_test_img

	echo
	echo "Take an internal snapshot:"

	$QEMU_IMG snapshot -c test "$TEST_IMG"
	_check_test_img

	echo
	echo "=== Standalone image with external data file (efficient) ==="
	echo

	_make_test_img -o "data_file=$TEST_IMG.data" 64M

	echo -n "qcow2 file size before I/O: "
	du -b $TEST_IMG \| cut -f1

	# Create image with the following layout
	# 0-1 MB: Unallocated
	# 1-2 MB: Written (pattern 0x11)
	# 2-3 MB: Discarded
	# 3-4 MB: Zero write over discarded space
	# 4-5 MB: Zero write over written space
	# 5-6 MB: Zero write over unallocated space

	echo
	$QEMU_IO -c 'write -P 0x11 1M 4M' \
	-c 'discard 2M 2M' \
	-c 'write -z 3M 3M' \
	-f $IMGFMT "$TEST_IMG" \|
	_filter_qemu_io
	_check_test_img

	echo
	$QEMU_IMG map --output=json "$TEST_IMG"

	echo
	$QEMU_IO -c 'read -P 0 0 1M' \
	-c 'read -P 0x11 1M 1M' \
	-c 'read -P 0 2M 4M' \
	-f $IMGFMT "$TEST_IMG" \|
	_filter_qemu_io

	# Zero clusters are only marked as such in the qcow2 metadata, but contain
	# stale data in the external data file
	echo
	$QEMU_IO -c 'read -P 0 0 1M' \
	-c 'read -P 0x11 1M 1M' \
	-c 'read -P 0x11 4M 1M' \
	-c 'read -P 0 5M 1M' \
	-f raw "$TEST_IMG.data" \|
	_filter_qemu_io


	echo -n "qcow2 file size after I/O: "
	du -b $TEST_IMG \| cut -f1

	echo
	echo "=== Standalone image with external data file (valid raw) ==="
	echo

	_make_test_img -o "data_file=$TEST_IMG.data,data_file_raw=on" 64M

	echo -n "qcow2 file size before I/O: "
	du -b $TEST_IMG \| cut -f1

	echo
	$QEMU_IO -c 'write -P 0x11 1M 4M' \
	-c 'discard 2M 2M' \
	-c 'write -z 3M 3M' \
	-f $IMGFMT "$TEST_IMG" \|
	_filter_qemu_io
	_check_test_img

	echo
	$QEMU_IMG map --output=json "$TEST_IMG"

	echo
	$QEMU_IO -c 'read -P 0 0 1M' \
	-c 'read -P 0x11 1M 1M' \
	-c 'read -P 0 2M 4M' \
	-f $IMGFMT "$TEST_IMG" \|
	_filter_qemu_io

	# Discarded clusters are only marked as such in the qcow2 metadata, but
	# they can contain stale data in the external data file. Instead, zero
	# clusters must be zeroed in the external data file too.
	echo
	$QEMU_IO -c 'read -P 0 0 1M' \
	-c 'read -P 0x11 1M 1M' \
	-c 'read -P 0 3M 3M' \
	-f raw "$TEST_IMG".data \|
	_filter_qemu_io

	echo -n "qcow2 file size after I/O: "
	du -b $TEST_IMG \| cut -f1

	echo
	echo "=== bdrv_co_block_status test for file and offset=0 ==="
	echo

	_make_test_img -o "data_file=$TEST_IMG.data" 64M

	$QEMU_IO -c 'write -P 0x11 0 1M' -f $IMGFMT "$TEST_IMG" \| _filter_qemu_io
	$QEMU_IO -c 'read -P 0x11 0 1M' -f $IMGFMT "$TEST_IMG" \| _filter_qemu_io
	$QEMU_IMG map --output=human "$TEST_IMG" \| _filter_testdir
	$QEMU_IMG map --output=json "$TEST_IMG"

	echo
	echo "=== Copy offloading ==="
	echo

	# Make use of copy offloading if the test host can provide it
	_make_test_img -o "data_file=$TEST_IMG.data" 64M
	$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
	$QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"

	# blkdebug doesn't support copy offloading, so this tests the error path
	$QEMU_IMG amend -f $IMGFMT -o "data_file=blkdebug::$TEST_IMG.data" "$TEST_IMG"
	$QEMU_IMG convert -f $IMGFMT -O $IMGFMT -n -C "$TEST_IMG.src" "$TEST_IMG"
	$QEMU_IMG compare -f $IMGFMT -F $IMGFMT "$TEST_IMG.src" "$TEST_IMG"

	echo
	echo "=== Flushing should flush the data file ==="
	echo

	# We are going to flush a qcow2 file with a blkdebug node inserted
	# between the qcow2 node and its data file node. The blkdebug node
	# will return an error for all flushes and so we if the data file is
	# flushed, we will see qemu-io return an error.

	# We need to write something or the flush will not do anything; we
	# also need -t writeback so the write is not done as a FUA write
	# (which would then fail thanks to the implicit flush)
	$QEMU_IO -c 'write 0 512' -c flush \
	-t writeback \
	"json:{
	'driver': 'qcow2',
	'file': {
	'driver': 'file',
	'filename': '$TEST_IMG'
	},
	'data-file': {
	'driver': 'blkdebug',
	'inject-error': [{
	'event': 'none',
	'iotype': 'flush'
	}],
	'image': {
	'driver': 'file',
	'filename': '$TEST_IMG.data'
	}
	}
	}" \
	\| _filter_qemu_io

	result=${PIPESTATUS[0]}
	echo

	case $result in
	0)
	echo "ERROR: qemu-io succeeded, so the data file was not flushed"
	;;
	1)
	echo "Success: qemu-io failed, so the data file was flushed"
	;;
	*)
	echo "ERROR: qemu-io returned unknown exit code $result"
	;;
	esac

	echo
	echo '=== Preallocation with data-file-raw ==='

	echo
	echo '--- Using a non-zeroed data file ---'

	# Using data-file-raw must enforce at least metadata preallocation so
	# that it does not matter whether one reads the raw file or the qcow2
	# file

	# Pre-create the data file, write some data. Real-world use cases for
	# this are adding a qcow2 metadata file to a block device (i.e., using
	# the device as the data file) or adding qcow2 features to pre-existing
	# raw images (e.g. because the user now wants persistent dirty bitmaps).
	truncate -s 1M "$TEST_IMG.data"
	$QEMU_IO -f raw -c 'write -P 42 0 1M' "$TEST_IMG.data" \| _filter_qemu_io

	# We cannot use qemu-img to create the qcow2 image, because it would
	# clear the data file. Use the blockdev-create job instead, which will
	# only format the qcow2 image file.
	touch "$TEST_IMG"
	_launch_qemu \
	-blockdev file,node-name=data,filename="$TEST_IMG.data" \
	-blockdev file,node-name=meta,filename="$TEST_IMG"

	_send_qemu_cmd $QEMU_HANDLE '{ "execute": "qmp_capabilities" }' 'return'

	_send_qemu_cmd $QEMU_HANDLE \
	'{ "execute": "blockdev-create",
	"arguments": {
	"job-id": "create",
	"options": {
	"driver": "qcow2",
	"size": '"$((1 * 1024 * 1024))"',
	"file": "meta",
	"data-file": "data",
	"data-file-raw": true
	} } }' \
	'"status": "concluded"'

	_send_qemu_cmd $QEMU_HANDLE \
	'{ "execute": "job-dismiss", "arguments": { "id": "create" } }' \
	'return'

	_cleanup_qemu

	echo
	echo 'Comparing pattern:'

	# Reading from either the qcow2 file or the data file should return
	# the same result:
	$QEMU_IO -f raw -c 'read -P 42 0 1M' "$TEST_IMG.data" \| _filter_qemu_io
	$QEMU_IO -f $IMGFMT -c 'read -P 42 0 1M' "$TEST_IMG" \| _filter_qemu_io

	# For good measure
	$QEMU_IMG compare -f raw "$TEST_IMG.data" "$TEST_IMG"

	echo
	echo '--- Truncation (growing) ---'

	# Append some new data to the raw file, then resize the qcow2 image
	# accordingly and see whether the new data is visible. Technically
	# that is not allowed, but it is reasonable behavior, so test it.
	truncate -s 2M "$TEST_IMG.data"
	$QEMU_IO -f raw -c 'write -P 84 1M 1M' "$TEST_IMG.data" \| _filter_qemu_io

	$QEMU_IMG resize "$TEST_IMG" 2M

	echo
	echo 'Comparing pattern:'

	$QEMU_IO -f raw -c 'read -P 42 0 1M' -c 'read -P 84 1M 1M' "$TEST_IMG.data" \
	\| _filter_qemu_io
	$QEMU_IO -f $IMGFMT -c 'read -P 42 0 1M' -c 'read -P 84 1M 1M' "$TEST_IMG" \
	\| _filter_qemu_io

	$QEMU_IMG compare -f raw "$TEST_IMG.data" "$TEST_IMG"

	echo
	echo '--- Giving a backing file at runtime ---'

	# qcow2 files with data-file-raw cannot have backing files given by
	# their image header, but qemu will allow you to set a backing node at
	# runtime -- it should not have any effect, though (because reading
	# from the qcow2 node should return the same data as reading from the
	# raw node).

	_make_test_img -o "data_file=$TEST_IMG.data,data_file_raw=on" 1M
	TEST_IMG="$TEST_IMG.base" _make_test_img 1M

	# Write something that is not zero into the base image
	$QEMU_IO -c 'write -P 42 0 1M' "$TEST_IMG.base" \| _filter_qemu_io

	echo
	echo 'Comparing qcow2 image and raw data file:'

	# $TEST_IMG and $TEST_IMG.data must show the same data at all times;
	# that is, the qcow2 node must not fall through to the backing image
	# at any point
	$QEMU_IMG compare --image-opts \
	"driver=raw,file.filename=$TEST_IMG.data" \
	"file.filename=$TEST_IMG,backing.file.filename=$TEST_IMG.base"

	# success, all done
	echo "*** done"
	rm -f $seq.full
	status=0