tests/qemu-iotests/121

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