qemu/tests/qemu-iotests/115

#!/usr/bin/env bash
# group: rw
#
# Test case for non-self-referential qcow2 refcount blocks
#
# 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=hreitz@redhat.com

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

_supported_fmt qcow2
_supported_proto file fuse
# This test relies on refcounts being 64 bits wide (which does not work with
# compat=0.10)
_unsupported_imgopts 'refcount_bits=\([^6]\|.\([^4]\|$\)\)' 'compat=0.10'

echo
echo '=== Testing large refcount and L1 table ==='
echo

# Create an image with an L1 table and a refcount table that each span twice the
# number of clusters which can be described by a single refblock; therefore, at
# least two refblocks cannot count their own refcounts because all the clusters
# they describe are part of the L1 table or refcount table.

# One refblock can describe (with cluster_size=512 and refcount_bits=64)
# 512/8 = 64 clusters, therefore the L1 table should cover 128 clusters, which
# equals 128 * (512/8) = 8192 entries (actually, 8192 - 512/8 = 8129 would
# suffice, but it does not really matter). 8192 L2 tables can in turn describe
# 8192 * 512/8 = 524,288 clusters which cover a space of 256 MB.

# Since with refcount_bits=64 every refcount block entry is 64 bits wide (just
# like the L2 table entries), the same calculation applies to the refcount table
# as well; the difference is that while for the L1 table the guest disk size is
# concerned, for the refcount table it is the image length that has to be at
# least 256 MB. We can achieve that by using preallocation=metadata for an image
# which has a guest disk size of 256 MB.

_make_test_img -o "refcount_bits=64,cluster_size=512,preallocation=metadata" 256M

# We know for sure that the L1 and refcount tables do not overlap with any other
# structure because the metadata overlap checks would have caught that case.

# Because qemu refuses to open qcow2 files whose L1 table does not cover the
# whole guest disk size, it is definitely large enough. On the other hand, to
# test whether the refcount table is large enough, we simply have to verify that
# indeed all the clusters are allocated, which is done by qemu-img check.

# The final thing we need to test is whether the tables are actually covered by
# refcount blocks; since all clusters of the tables are referenced, we can use
# qemu-img check for that purpose, too.

$QEMU_IMG check "$TEST_IMG" | \
    sed -e 's/^.* = \([0-9]\+\.[0-9]\+% allocated\).*\(clusters\)$/\1 \2/' \
        -e '/^Image end offset/d'

# (Note that we cannot use _check_test_img because that function filters out the
# allocation status)

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