1#!/usr/bin/env 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 $seq" 26 27status=1 # failure is the default! 28 29_cleanup() 30{ 31 _cleanup_test_img 32} 33trap "_cleanup; exit \$status" 0 1 2 3 15 34 35# get standard environment, filters and checks 36. ./common.rc 37. ./common.filter 38 39_supported_fmt qcow2 40_supported_proto file 41_supported_os Linux 42# Refcount structures are used much differently with external data 43# files 44_unsupported_imgopts data_file 45 46echo 47echo '=== New refcount structures may not conflict with existing structures ===' 48 49echo 50echo '--- Test 1 ---' 51echo 52 53# Preallocation speeds up the write operation, but preallocating everything will 54# destroy the purpose of the write; so preallocate one KB less than what would 55# cause a reftable growth... 56_make_test_img -o 'preallocation=metadata,cluster_size=1k' 64512K 57# ...and make the image the desired size afterwards. 58$QEMU_IMG resize "$TEST_IMG" 65M 59 60# The first write results in a growth of the refcount table during an allocation 61# which has precisely the required size so that the new refcount block allocated 62# in alloc_refcount_block() is right after cluster_index; this did lead to a 63# different refcount block being written to disk (a zeroed cluster) than what is 64# cached (a refblock with one entry having a refcount of 1), and the second 65# write would then result in that cached cluster being marked dirty and then 66# in it being written to disk. 67# This should not happen, the new refcount structures may not conflict with 68# new_block. 69# (Note that for some reason, 'write 63M 1K' does not trigger the problem) 70$QEMU_IO -c 'write 62M 1025K' -c 'write 64M 1M' "$TEST_IMG" | _filter_qemu_io 71 72_check_test_img 73 74 75echo 76echo '--- Test 2 ---' 77echo 78 79_make_test_img -o 'preallocation=metadata,cluster_size=1k' 64513K 80# This results in an L1 table growth which in turn results in some clusters at 81# the start of the image becoming free 82$QEMU_IMG resize "$TEST_IMG" 65M 83 84# This write results in a refcount table growth; but the refblock allocated 85# immediately before that (new_block) takes cluster index 4 (which is now free) 86# and is thus not self-describing (in contrast to test 1, where new_block was 87# self-describing). The refcount table growth algorithm then used to place the 88# new refcount structures at cluster index 65536 (which is the same as the 89# cluster_index parameter in this case), allocating a new refcount block for 90# that cluster while new_block already existed, leaking new_block. 91# Therefore, the new refcount structures may not be put at cluster_index 92# (because new_block already describes that cluster, and the new structures try 93# to be self-describing). 94$QEMU_IO -c 'write 63M 130K' "$TEST_IMG" | _filter_qemu_io 95 96_check_test_img 97 98echo 99echo '=== Allocating a new refcount block must not leave holes in the image ===' 100echo 101 102_make_test_img -o 'cluster_size=512,refcount_bits=16' 1M 103 104# This results in an image with 256 used clusters: the qcow2 header, 105# the refcount table, one refcount block, the L1 table, four L2 tables 106# and 248 data clusters 107$QEMU_IO -c 'write 0 124k' "$TEST_IMG" | _filter_qemu_io 108 109# 256 clusters of 512 bytes each give us a 128K image 110stat -c "size=%s (expected 131072)" $TEST_IMG 111 112# All 256 entries of the refcount block are used, so writing a new 113# data cluster also allocates a new refcount block 114$QEMU_IO -c 'write 124k 512' "$TEST_IMG" | _filter_qemu_io 115 116# Two more clusters, the image size should be 129K now 117stat -c "size=%s (expected 132096)" $TEST_IMG 118 119# success, all done 120echo 121echo '*** done' 122rm -f $seq.full 123status=0 124