qcow: Tolerate backing_fmt=
qcow has no space in the metadata to store a backing format, and there are existing qcow images backed both by raw or by other formats (usually qcow) images, reliant on probing to tell the difference. On the bright side, because we probe every time, raw files are marked as probed and we thus forbid a commit action into the backing file where guest-controlled contents could change the result of the probe next time around (the iotest added here proves that). Still, allowing the user to specify the backing format during creation, even if we can't record it, is a good thing. This patch blindly allows any value that resolves to a known driver, even if the user's request is a mismatch from what probing finds; then the next patch will further enhance things to verify that the user's request matches what we actually probe. With this and the next patch in place, we will finally be ready to deprecate the creation of images where a backing format was not explicitly specified by the user. Note that this is only for QemuOpts usage; there is no change to the QAPI to allow a format through -blockdev. Add a new iotest 301 just for qcow, to demonstrate the latest behavior, and to make it easier to show the improvements made in the next patch. Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200706203954.341758-6-eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake
Kevin Wolf
parent
d51a814cf4
commit
344acbd62f
20
block/qcow.c
20
block/qcow.c
@ -938,10 +938,11 @@ static int coroutine_fn qcow_co_create_opts(BlockDriver *drv,
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{
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BlockdevCreateOptions *create_options = NULL;
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BlockDriverState *bs = NULL;
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QDict *qdict;
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QDict *qdict = NULL;
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Visitor *v;
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const char *val;
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int ret;
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char *backing_fmt;
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static const QDictRenames opt_renames[] = {
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{ BLOCK_OPT_BACKING_FILE, "backing-file" },
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@ -949,6 +950,17 @@ static int coroutine_fn qcow_co_create_opts(BlockDriver *drv,
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{ NULL, NULL },
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};
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/*
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* We can't actually store a backing format, but can check that
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* the user's request made sense.
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*/
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backing_fmt = qemu_opt_get_del(opts, BLOCK_OPT_BACKING_FMT);
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if (backing_fmt && !bdrv_find_format(backing_fmt)) {
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error_setg(errp, "unrecognized backing format '%s'", backing_fmt);
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ret = -EINVAL;
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goto fail;
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}
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/* Parse options and convert legacy syntax */
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qdict = qemu_opts_to_qdict_filtered(opts, NULL, &qcow_create_opts, true);
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@ -1012,6 +1024,7 @@ static int coroutine_fn qcow_co_create_opts(BlockDriver *drv,
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ret = 0;
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fail:
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g_free(backing_fmt);
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qobject_unref(qdict);
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bdrv_unref(bs);
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qapi_free_BlockdevCreateOptions(create_options);
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@ -1146,6 +1159,11 @@ static QemuOptsList qcow_create_opts = {
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.type = QEMU_OPT_STRING,
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.help = "File name of a base image"
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},
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{
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.name = BLOCK_OPT_BACKING_FMT,
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.type = QEMU_OPT_STRING,
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.help = "Format of the backing image",
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},
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{
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.name = BLOCK_OPT_ENCRYPT,
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.type = QEMU_OPT_BOOL,
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88
tests/qemu-iotests/301
Executable file
88
tests/qemu-iotests/301
Executable file
@ -0,0 +1,88 @@
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#!/usr/bin/env bash
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#
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# Test qcow backing file warnings
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#
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# Copyright (C) 2020 Red Hat, Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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seq=`basename $0`
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echo "QA output created by $seq"
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status=1 # failure is the default!
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_cleanup()
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{
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_cleanup_test_img
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_rm_test_img "$TEST_IMG.qcow2"
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}
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trap "_cleanup; exit \$status" 0 1 2 3 15
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# get standard environment, filters and checks
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. ./common.rc
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. ./common.filter
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_supported_fmt qcow
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_supported_proto file
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_supported_os Linux
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size=32M
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echo
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echo "== qcow backed by qcow =="
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TEST_IMG="$TEST_IMG.base" _make_test_img $size
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_make_test_img -b "$TEST_IMG.base" $size
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_img_info
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_make_test_img -b "$TEST_IMG.base" -F $IMGFMT $size
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_img_info
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echo
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echo "== mismatched command line detection =="
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_make_test_img -b "$TEST_IMG.base" -F vmdk
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_make_test_img -b "$TEST_IMG.base" -F vmdk $size
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echo
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# Use of -u bypasses the backing format sanity check
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_make_test_img -u -b "$TEST_IMG.base" -F vmdk
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_make_test_img -u -b "$TEST_IMG.base" -F vmdk $size
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echo
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# But the format must still be recognized
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_make_test_img -b "$TEST_IMG.base" -F garbage $size
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_make_test_img -u -b "$TEST_IMG.base" -F garbage $size
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_img_info
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echo
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echo "== qcow backed by raw =="
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rm "$TEST_IMG.base"
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truncate --size=$size "$TEST_IMG.base"
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_make_test_img -b "$TEST_IMG.base" $size
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_img_info
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_make_test_img -b "$TEST_IMG.base" -F raw $size
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_img_info
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echo
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echo "== commit cannot change type of raw backing file =="
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TEST_IMG="$TEST_IMG.qcow2" IMGFMT=qcow2 _make_test_img $size
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truncate --size=$size "$TEST_IMG.qcow2"
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$QEMU_IMG convert -n -f raw -O $IMGFMT "$TEST_IMG.qcow2" "$TEST_IMG"
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$QEMU_IMG commit -f $IMGFMT "$TEST_IMG" && echo "unexpected success"
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TEST_IMG="$TEST_IMG.base" _img_info
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# success, all done
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echo "*** done"
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rm -f $seq.full
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status=0
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60
tests/qemu-iotests/301.out
Normal file
60
tests/qemu-iotests/301.out
Normal file
@ -0,0 +1,60 @@
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QA output created by 301
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== qcow backed by qcow ==
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Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=33554432
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 32 MiB (33554432 bytes)
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cluster_size: 512
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backing file: TEST_DIR/t.IMGFMT.base
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 32 MiB (33554432 bytes)
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cluster_size: 512
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backing file: TEST_DIR/t.IMGFMT.base
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== mismatched command line detection ==
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qemu-img: TEST_DIR/t.IMGFMT: invalid VMDK image descriptor
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Could not open backing image to determine size.
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qemu-img: warning: Could not verify backing image. This may become an error in future versions.
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invalid VMDK image descriptor
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=vmdk
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qemu-img: TEST_DIR/t.IMGFMT: Image creation needs a size parameter
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=vmdk
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qemu-img: warning: Could not verify backing image. This may become an error in future versions.
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Unknown driver 'garbage'
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=garbage
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qemu-img: TEST_DIR/t.IMGFMT: unrecognized backing format 'garbage'
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=garbage
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qemu-img: TEST_DIR/t.IMGFMT: unrecognized backing format 'garbage'
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 32 MiB (33554432 bytes)
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cluster_size: 512
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backing file: TEST_DIR/t.IMGFMT.base
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== qcow backed by raw ==
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 32 MiB (33554432 bytes)
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cluster_size: 512
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backing file: TEST_DIR/t.IMGFMT.base
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=raw
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image: TEST_DIR/t.IMGFMT
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file format: IMGFMT
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virtual size: 32 MiB (33554432 bytes)
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cluster_size: 512
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backing file: TEST_DIR/t.IMGFMT.base
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== commit cannot change type of raw backing file ==
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Formatting 'TEST_DIR/t.qcow.IMGFMT', fmt=IMGFMT size=33554432
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qemu-img: Block job failed: Operation not permitted
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image: TEST_DIR/t.IMGFMT.base
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file format: raw
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virtual size: 32 MiB (33554432 bytes)
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*** done
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@ -306,3 +306,4 @@
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295 rw
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296 rw
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297 meta
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301 backing quick
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