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