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