tests/qemu-iotests/121

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