qemu-e2k/tests/qemu-iotests/097
Eric Blake a3e1505dae qcow2: Don't strand clusters near 2G intervals during commit
The qcow2_make_empty() function is reached during 'qemu-img commit',
in order to clear out ALL clusters of an image.  However, if the
image cannot use the fast code path (true if the image is format
0.10, or if the image contains a snapshot), the cluster size is
larger than 512, and the image is larger than 2G in size, then our
choice of sector_step causes problems.  Since it is not cluster
aligned, but qcow2_discard_clusters() silently ignores an unaligned
head or tail, we are leaving clusters allocated.

Enhance the testsuite to expose the flaw, and patch the problem by
ensuring our step size is aligned.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-12-06 15:37:02 +01:00

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#!/bin/bash
#
# Commit changes into backing chains and empty the top image if the
# backing image is not explicitly specified
#
# Copyright (C) 2014 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=mreitz@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
_rm_test_img "$TEST_IMG.itmd"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
. ./common.pattern
# Any format supporting backing files and bdrv_make_empty
_supported_fmt qcow qcow2
_supported_proto file
_supported_os Linux
# Four main passes:
# 0: Two-layer backing chain, commit to upper backing file (implicitly)
# (in this case, the top image will be emptied)
# 1: Two-layer backing chain, commit to upper backing file (explicitly)
# (in this case, the top image will implicitly stay unchanged)
# 2: Two-layer backing chain, commit to upper backing file (implicitly with -d)
# (in this case, the top image will explicitly stay unchanged)
# 3: Two-layer backing chain, commit to lower backing file
# (in this case, the top image will implicitly stay unchanged)
#
# Each pass is run twice, since qcow2 has different code paths for cleaning
# an image depending on whether it has a snapshot.
#
# 020 already tests committing, so this only tests whether image chains are
# working properly and that all images above the base are emptied; therefore,
# no complicated patterns are necessary. Check near the 2G mark, as qcow2
# has been buggy at that boundary in the past.
for i in 0 1 2 3; do
for j in 0 1; do
echo
echo "=== Test pass $i.$j ==="
echo
TEST_IMG="$TEST_IMG.base" _make_test_img 2100M
TEST_IMG="$TEST_IMG.itmd" _make_test_img -b "$TEST_IMG.base" 2100M
_make_test_img -b "$TEST_IMG.itmd" 2100M
if [ $j -eq 0 ]; then
$QEMU_IMG snapshot -c snap "$TEST_IMG"
fi
$QEMU_IO -c 'write -P 1 0x7ffd0000 192k' "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c 'write -P 2 0x7ffe0000 128k' "$TEST_IMG.itmd" | _filter_qemu_io
$QEMU_IO -c 'write -P 3 0x7fff0000 64k' "$TEST_IMG" | _filter_qemu_io
if [ $i -lt 3 ]; then
if [ $i == 0 ]; then
# -b "$TEST_IMG.itmd" should be the default (that is, committing to the
# first backing file in the chain)
$QEMU_IMG commit "$TEST_IMG"
elif [ $i == 1 ]; then
# explicitly specify the commit target (this should imply -d)
$QEMU_IMG commit -b "$TEST_IMG.itmd" "$TEST_IMG"
else
# do not explicitly specify the commit target, but use -d to leave the
# top image unchanged
$QEMU_IMG commit -d "$TEST_IMG"
fi
# Bottom should be unchanged
$QEMU_IO -c 'read -P 1 0x7ffd0000 192k' "$TEST_IMG.base" | _filter_qemu_io
# Intermediate should contain changes from top
$QEMU_IO -c 'read -P 1 0x7ffd0000 64k' "$TEST_IMG.itmd" | _filter_qemu_io
$QEMU_IO -c 'read -P 2 0x7ffe0000 64k' "$TEST_IMG.itmd" | _filter_qemu_io
$QEMU_IO -c 'read -P 3 0x7fff0000 64k' "$TEST_IMG.itmd" | _filter_qemu_io
# And in pass 0, the top image should be empty, whereas in both other passes
# it should be unchanged (which is both checked by qemu-img map)
else
$QEMU_IMG commit -b "$TEST_IMG.base" "$TEST_IMG"
# Bottom should contain all changes
$QEMU_IO -c 'read -P 1 0x7ffd0000 64k' "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c 'read -P 2 0x7ffe0000 64k' "$TEST_IMG.base" | _filter_qemu_io
$QEMU_IO -c 'read -P 3 0x7fff0000 64k' "$TEST_IMG.base" | _filter_qemu_io
# Both top and intermediate should be unchanged
fi
$QEMU_IMG map "$TEST_IMG.base" | _filter_qemu_img_map
$QEMU_IMG map "$TEST_IMG.itmd" | _filter_qemu_img_map
$QEMU_IMG map "$TEST_IMG" | _filter_qemu_img_map
done
done
# success, all done
echo "*** done"
rm -f $seq.full
status=0