1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
|
#!/bin/bash
#
# Test cases for qcow2 refcount table growth
#
# Copyright (C) 2015 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=mreitz@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
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
_supported_os Linux
echo
echo '=== New refcount structures may not conflict with existing structures ==='
echo
echo '--- Test 1 ---'
echo
# Preallocation speeds up the write operation, but preallocating everything will
# destroy the purpose of the write; so preallocate one KB less than what would
# cause a reftable growth...
IMGOPTS='preallocation=metadata,cluster_size=1k' _make_test_img 64512K
# ...and make the image the desired size afterwards.
$QEMU_IMG resize "$TEST_IMG" 65M
# The first write results in a growth of the refcount table during an allocation
# which has precisely the required size so that the new refcount block allocated
# in alloc_refcount_block() is right after cluster_index; this did lead to a
# different refcount block being written to disk (a zeroed cluster) than what is
# cached (a refblock with one entry having a refcount of 1), and the second
# write would then result in that cached cluster being marked dirty and then
# in it being written to disk.
# This should not happen, the new refcount structures may not conflict with
# new_block.
# (Note that for some reason, 'write 63M 1K' does not trigger the problem)
$QEMU_IO -c 'write 62M 1025K' -c 'write 64M 1M' "$TEST_IMG" | _filter_qemu_io
_check_test_img
echo
echo '--- Test 2 ---'
echo
IMGOPTS='preallocation=metadata,cluster_size=1k' _make_test_img 64513K
# This results in an L1 table growth which in turn results in some clusters at
# the start of the image becoming free
$QEMU_IMG resize "$TEST_IMG" 65M
# This write results in a refcount table growth; but the refblock allocated
# immediately before that (new_block) takes cluster index 4 (which is now free)
# and is thus not self-describing (in contrast to test 1, where new_block was
# self-describing). The refcount table growth algorithm then used to place the
# new refcount structures at cluster index 65536 (which is the same as the
# cluster_index parameter in this case), allocating a new refcount block for
# that cluster while new_block already existed, leaking new_block.
# Therefore, the new refcount structures may not be put at cluster_index
# (because new_block already describes that cluster, and the new structures try
# to be self-describing).
$QEMU_IO -c 'write 63M 130K' "$TEST_IMG" | _filter_qemu_io
_check_test_img
echo
echo '=== Allocating a new refcount block must not leave holes in the image ==='
echo
IMGOPTS='cluster_size=512,refcount_bits=16' _make_test_img 1M
# This results in an image with 256 used clusters: the qcow2 header,
# the refcount table, one refcount block, the L1 table, four L2 tables
# and 248 data clusters
$QEMU_IO -c 'write 0 124k' "$TEST_IMG" | _filter_qemu_io
# 256 clusters of 512 bytes each give us a 128K image
stat -c "size=%s (expected 131072)" $TEST_IMG
# All 256 entries of the refcount block are used, so writing a new
# data cluster also allocates a new refcount block
$QEMU_IO -c 'write 124k 512' "$TEST_IMG" | _filter_qemu_io
# Two more clusters, the image size should be 129K now
stat -c "size=%s (expected 132096)" $TEST_IMG
# success, all done
echo
echo '*** done'
rm -f $seq.full
status=0
|
