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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 23 owner=hreitz@redhat.com 24 25 seq="$(basename $0)" 26 echo "QA output created by $seq" 27 28 status=1 # failure is the default! 29 30 _cleanup() 31 { 32 _cleanup_test_img 33 } 34 trap "_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 47 echo 48 echo '=== New refcount structures may not conflict with existing structures ===' 49 50 echo 51 echo '--- Test 1 ---' 52 echo 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 76 echo 77 echo '--- Test 2 ---' 78 echo 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 99 echo 100 echo '=== Allocating a new refcount block must not leave holes in the image ===' 101 echo 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 111 stat -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 118 stat -c "size=%s (expected 132096)" $TEST_IMG 119 120 # success, all done 121 echo 122 echo '*** done' 123 rm -f $seq.full 124 status=0