tests/qemu-iotests/121

   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=mreitz@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