iotests: Add test for 4G+ compressed qcow2 write

#!/usr/bin/env bash

#

# Test compressed write to a qcow2 image at an offset above 4 GB

#

# 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/>.

#

seq=$(basename "$0")

echo "QA output created by $seq"

status=1	# failure is the default!

_cleanup()

{

    _cleanup_test_img

}

trap "_cleanup; exit \$status" 0 1 2 3 15

# get standard environment, filters and checks

. ./common.rc

. ./common.filter

# This is a qcow2 regression test

_supported_fmt qcow2

_supported_proto file

# External data files do not support compression;

# We need an exact cluster size (2M) and refcount width (2) so we can

# get this test quickly over with; and this in turn require

# compat=1.1

_unsupported_imgopts data_file cluster_size refcount_bits 'compat=0.10'

# The idea is: Create an empty file, mark the first 4 GB as used, then

# do a compressed write that thus must be put beyond 4 GB.

# (This used to fail because the compressed sector mask was just a

# 32 bit mask, so qemu-img check will count a cluster before 4 GB as

# referenced twice.)

# We would like to use refcount_bits=1 here, but then qemu-img check

# will throw an error when trying to count a cluster as referenced

# twice.

_make_test_img -o cluster_size=2M,refcount_bits=2 64M

reft_offs=$(peek_file_be "$TEST_IMG" 48 8)

refb_offs=$(peek_file_be "$TEST_IMG" $reft_offs 8)

# We want to cover 4 GB, those are 2048 clusters, equivalent to

# 4096 bit = 512 B.

truncate -s 4G "$TEST_IMG"

for ((in_refb_offs = 0; in_refb_offs < 512; in_refb_offs += 8)); do

    poke_file "$TEST_IMG" $((refb_offs + in_refb_offs)) \

        '\x55\x55\x55\x55\x55\x55\x55\x55'

done

$QEMU_IO -c 'write -c -P 42 0 2M' "$TEST_IMG" | _filter_qemu_io

echo

echo '--- Check ---'

# This should only print the leaked clusters in the first 4 GB

_check_test_img | grep -v '^Leaked cluster '

# success, all done

echo "*** done"

rm -f $seq.full

status=0

QA output created by 272

Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864

wrote 2097152/2097152 bytes at offset 0

2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)

--- Check ---

2044 leaked clusters were found on the image.

This means waste of disk space, but no harm to data.

*** done

267 rw auto quick snapshot

268 rw auto quick

270 rw backing quick

272 rw