048c5fd1bf
As mentioned in commit 0c1bd46, we ignored requests to
discard the trailing cluster of an unaligned image. While
discard is an advisory operation from the guest standpoint,
(and we are therefore free to ignore any request), our
qcow2 implementation exploits the fact that a discarded
cluster reads back as 0. As long as we discard on cluster
boundaries, we are fine; but that means we could observe
non-zero data leaked at the tail of an unaligned image.
Enhance iotest 66 to cover this case, and fix the implementation
to honor a discard request on the final partial cluster.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170407013709.18440-1-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
65 lines
1.7 KiB
Bash
Executable file
65 lines
1.7 KiB
Bash
Executable file
#!/bin/bash
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#
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# Test case for discarding preallocated zero clusters in qcow2
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#
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# Copyright (C) 2013 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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# creator
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owner=mreitz@redhat.com
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seq="$(basename $0)"
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echo "QA output created by $seq"
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here="$PWD"
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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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}
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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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# This tests qocw2-specific low-level functionality
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_supported_fmt qcow2
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_supported_proto generic
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_supported_os Linux
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# Intentionally create an unaligned image
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IMGOPTS="compat=1.1"
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IMG_SIZE=$((64 * 1024 * 1024 + 512))
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echo
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echo "=== Testing cluster discards ==="
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echo
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_make_test_img $IMG_SIZE
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# Write some normal clusters, zero some of them (creating preallocated
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# zero clusters) and discard everything. Everything should now read as 0.
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$QEMU_IO -c "write 0 256k" -c "write -z 0 256k" -c "write 64M 512" \
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-c "discard 0 $IMG_SIZE" -c "read -P 0 0 $IMG_SIZE" "$TEST_IMG" \
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| _filter_qemu_io
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# Check the image (there shouldn't be any leaks)
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_check_test_img
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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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