1#!/bin/bash 2# 3# Test cases for qcow2 refcount table growth 4# 5# Copyright (C) 2015 Red Hat, Inc. 6# 7# This program is free software; you can redistribute it and/or modify 8# it under the terms of the GNU General Public License as published by 9# the Free Software Foundation; either version 2 of the License, or 10# (at your option) any later version. 11# 12# This program is distributed in the hope that it will be useful, 13# but WITHOUT ANY WARRANTY; without even the implied warranty of 14# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15# GNU General Public License for more details. 16# 17# You should have received a copy of the GNU General Public License 18# along with this program. If not, see <http://www.gnu.org/licenses/>. 19# 20 21# creator 22owner=mreitz@redhat.com 23 24seq="$(basename $0)" 25echo "QA output created by $seq" 26 27here="$PWD" 28tmp=/tmp/$$ 29status=1 # failure is the default! 30 31_cleanup() 32{ 33 _cleanup_test_img 34} 35trap "_cleanup; exit \$status" 0 1 2 3 15 36 37# get standard environment, filters and checks 38. ./common.rc 39. ./common.filter 40 41_supported_fmt qcow2 42_supported_proto file 43_supported_os Linux 44 45echo 46echo '=== New refcount structures may not conflict with existing structures ===' 47 48echo 49echo '--- Test 1 ---' 50echo 51 52# Preallocation speeds up the write operation, but preallocating everything will 53# destroy the purpose of the write; so preallocate one KB less than what would 54# cause a reftable growth... 55IMGOPTS='preallocation=metadata,cluster_size=1k' _make_test_img 64512K 56# ...and make the image the desired size afterwards. 57$QEMU_IMG resize "$TEST_IMG" 65M 58 59# The first write results in a growth of the refcount table during an allocation 60# which has precisely the required size so that the new refcount block allocated 61# in alloc_refcount_block() is right after cluster_index; this did lead to a 62# different refcount block being written to disk (a zeroed cluster) than what is 63# cached (a refblock with one entry having a refcount of 1), and the second 64# write would then result in that cached cluster being marked dirty and then 65# in it being written to disk. 66# This should not happen, the new refcount structures may not conflict with 67# new_block. 68# (Note that for some reason, 'write 63M 1K' does not trigger the problem) 69$QEMU_IO -c 'write 62M 1025K' -c 'write 64M 1M' "$TEST_IMG" | _filter_qemu_io 70 71_check_test_img 72 73 74echo 75echo '--- Test 2 ---' 76echo 77 78IMGOPTS='preallocation=metadata,cluster_size=1k' _make_test_img 64513K 79# This results in an L1 table growth which in turn results in some clusters at 80# the start of the image becoming free 81$QEMU_IMG resize "$TEST_IMG" 65M 82 83# This write results in a refcount table growth; but the refblock allocated 84# immediately before that (new_block) takes cluster index 4 (which is now free) 85# and is thus not self-describing (in contrast to test 1, where new_block was 86# self-describing). The refcount table growth algorithm then used to place the 87# new refcount structures at cluster index 65536 (which is the same as the 88# cluster_index parameter in this case), allocating a new refcount block for 89# that cluster while new_block already existed, leaking new_block. 90# Therefore, the new refcount structures may not be put at cluster_index 91# (because new_block already describes that cluster, and the new structures try 92# to be self-describing). 93$QEMU_IO -c 'write 63M 130K' "$TEST_IMG" | _filter_qemu_io 94 95_check_test_img 96 97 98# success, all done 99echo 100echo '*** done' 101rm -f $seq.full 102status=0 103