1#!/usr/bin/env bash 2# group: rw 3# 4# Test cases for qcow2 refcount table growth 5# 6# Copyright (C) 2015 Red Hat, Inc. 7# 8# This program is free software; you can redistribute it and/or modify 9# it under the terms of the GNU General Public License as published by 10# the Free Software Foundation; either version 2 of the License, or 11# (at your option) any later version. 12# 13# This program is distributed in the hope that it will be useful, 14# but WITHOUT ANY WARRANTY; without even the implied warranty of 15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16# GNU General Public License for more details. 17# 18# You should have received a copy of the GNU General Public License 19# along with this program. If not, see <http://www.gnu.org/licenses/>. 20# 21 22# creator 23owner=mreitz@redhat.com 24 25seq="$(basename $0)" 26echo "QA output created by $seq" 27 28status=1 # failure is the default! 29 30_cleanup() 31{ 32 _cleanup_test_img 33} 34trap "_cleanup; exit \$status" 0 1 2 3 15 35 36# get standard environment, filters and checks 37. ./common.rc 38. ./common.filter 39 40_supported_fmt qcow2 41_supported_proto file fuse 42_supported_os Linux 43# Refcount structures are used much differently with external data 44# files 45_unsupported_imgopts data_file 46 47echo 48echo '=== New refcount structures may not conflict with existing structures ===' 49 50echo 51echo '--- Test 1 ---' 52echo 53 54# Preallocation speeds up the write operation, but preallocating everything will 55# destroy the purpose of the write; so preallocate one KB less than what would 56# cause a reftable growth... 57_make_test_img -o 'preallocation=metadata,cluster_size=1k' 64512K 58# ...and make the image the desired size afterwards. 59$QEMU_IMG resize "$TEST_IMG" 65M 60 61# The first write results in a growth of the refcount table during an allocation 62# which has precisely the required size so that the new refcount block allocated 63# in alloc_refcount_block() is right after cluster_index; this did lead to a 64# different refcount block being written to disk (a zeroed cluster) than what is 65# cached (a refblock with one entry having a refcount of 1), and the second 66# write would then result in that cached cluster being marked dirty and then 67# in it being written to disk. 68# This should not happen, the new refcount structures may not conflict with 69# new_block. 70# (Note that for some reason, 'write 63M 1K' does not trigger the problem) 71$QEMU_IO -c 'write 62M 1025K' -c 'write 64M 1M' "$TEST_IMG" | _filter_qemu_io 72 73_check_test_img 74 75 76echo 77echo '--- Test 2 ---' 78echo 79 80_make_test_img -o 'preallocation=metadata,cluster_size=1k' 64513K 81# This results in an L1 table growth which in turn results in some clusters at 82# the start of the image becoming free 83$QEMU_IMG resize "$TEST_IMG" 65M 84 85# This write results in a refcount table growth; but the refblock allocated 86# immediately before that (new_block) takes cluster index 4 (which is now free) 87# and is thus not self-describing (in contrast to test 1, where new_block was 88# self-describing). The refcount table growth algorithm then used to place the 89# new refcount structures at cluster index 65536 (which is the same as the 90# cluster_index parameter in this case), allocating a new refcount block for 91# that cluster while new_block already existed, leaking new_block. 92# Therefore, the new refcount structures may not be put at cluster_index 93# (because new_block already describes that cluster, and the new structures try 94# to be self-describing). 95$QEMU_IO -c 'write 63M 130K' "$TEST_IMG" | _filter_qemu_io 96 97_check_test_img 98 99echo 100echo '=== Allocating a new refcount block must not leave holes in the image ===' 101echo 102 103_make_test_img -o 'cluster_size=512,refcount_bits=16' 1M 104 105# This results in an image with 256 used clusters: the qcow2 header, 106# the refcount table, one refcount block, the L1 table, four L2 tables 107# and 248 data clusters 108$QEMU_IO -c 'write 0 124k' "$TEST_IMG" | _filter_qemu_io 109 110# 256 clusters of 512 bytes each give us a 128K image 111stat -c "size=%s (expected 131072)" $TEST_IMG 112 113# All 256 entries of the refcount block are used, so writing a new 114# data cluster also allocates a new refcount block 115$QEMU_IO -c 'write 124k 512' "$TEST_IMG" | _filter_qemu_io 116 117# Two more clusters, the image size should be 129K now 118stat -c "size=%s (expected 132096)" $TEST_IMG 119 120# success, all done 121echo 122echo '*** done' 123rm -f $seq.full 124status=0 125