qemu-iotests: add read/write from smaller backing image test

Some image formats support backing images that are smaller than the
image file.  This patch adds a test that verifies that reads and writes
beyond the end of backing image work.

Unallocated reads beyond the end of the backing file should produce
zeroes.

Writes beyond the end of the backing file should copy-on-write using
zeroes.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

3 files changed, 560 insertions, 0 deletions

diff --git a/tests/qemu-iotests/028 b/tests/qemu-iotests/028
new file mode 100755
index 0000000000..0ca220e88e
--- /dev/null
+++ b/tests/qemu-iotests/028
@@ -0,0 +1,101 @@
+#!/bin/bash
+#
+# Test that backing files can be smaller than the image
+#
+# Copyright (C) 2010 IBM, Corp.
+#
+# Based on 017:
+# Copyright (C) 2009 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=stefanha@linux.vnet.ibm.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.pattern
+
+# Any format supporting backing files except vmdk and qcow which do not support
+# smaller backing files.
+_supported_fmt qcow2
+_supported_os Linux
+
+# Choose a size that is not necessarily a cluster size multiple for image
+# formats that use clusters.  This will ensure that the base image doesn't end
+# precisely on a cluster boundary (the easy case).
+image_size=$(( 4 * 1024 * 1024 * 1024 + 3 * 512 ))
+
+# The base image is smaller than the image file
+base_size=$(( image_size - 1024 * 1024 * 1024 ))
+
+offset=$(( base_size - 32 * 1024 ))
+
+_make_test_img $base_size
+
+echo "Filling base image"
+echo
+
+# Fill end of base image with a pattern, skipping every other sector
+io writev $offset 512 1024 31
+
+_check_test_img
+
+echo "Creating test image with backing file"
+echo
+
+mv $TEST_IMG $TEST_IMG.base
+_make_test_img -b $TEST_IMG.base $image_size
+
+echo "Filling test image"
+echo
+
+# Write every other sector around where the base image ends
+io writev $(( offset + 512 )) 512 1024 63
+
+_check_test_img
+
+echo "Reading"
+echo
+
+# Base image sectors
+io readv $(( offset )) 512 1024 31
+
+# Image sectors
+io readv $(( offset + 512 )) 512 1024 63
+
+# Zero sectors beyond end of base image
+io_zero readv $(( offset + 32 * 1024 )) 512 1024 31
+
+_check_test_img
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/028.out b/tests/qemu-iotests/028.out
new file mode 100644
index 0000000000..17460ed24d
--- /dev/null
+++ b/tests/qemu-iotests/028.out
@@ -0,0 +1,458 @@
+QA output created by 028
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=3221227008 
+Filling base image
+
+=== IO: pattern 195
+qemu-io> wrote 512/512 bytes at offset 3221195264
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221196288
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221197312
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221198336
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221199360
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221200384
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221201408
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221202432
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221203456
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221204480
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221205504
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221206528
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221207552
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221208576
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221209600
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221210624
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221211648
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221212672
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221213696
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221214720
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221215744
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221216768
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221217792
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221218816
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221219840
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221220864
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221221888
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221222912
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221223936
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221224960
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221225984
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> No errors were found on the image.
+Creating test image with backing file
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4294968832 backing_file='TEST_DIR/t.IMGFMT.base' 
+Filling test image
+
+=== IO: pattern 196
+qemu-io> wrote 512/512 bytes at offset 3221195776
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221196800
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221197824
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221198848
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221199872
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221200896
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221201920
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221202944
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221203968
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221204992
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221206016
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221207040
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221208064
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221209088
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221210112
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221211136
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221212160
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221213184
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221214208
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221215232
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221216256
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221217280
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221218304
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221219328
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221220352
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221221376
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221222400
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221223424
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221224448
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221225472
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221226496
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221227520
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221228544
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221229568
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221230592
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221231616
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221232640
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221233664
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221234688
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221235712
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221236736
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221237760
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221238784
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221239808
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221240832
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221241856
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221242880
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221243904
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221244928
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221245952
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221246976
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221248000
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221249024
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221250048
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221251072
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221252096
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221253120
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221254144
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221255168
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221256192
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221257216
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221258240
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 512/512 bytes at offset 3221259264
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> No errors were found on the image.
+Reading
+
+=== IO: pattern 195
+qemu-io> read 512/512 bytes at offset 3221195264
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221196288
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221197312
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221198336
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221199360
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221200384
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221201408
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221202432
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221203456
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221204480
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221205504
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221206528
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221207552
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221208576
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221209600
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221210624
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221211648
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221212672
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221213696
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221214720
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221215744
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221216768
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221217792
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221218816
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221219840
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221220864
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221221888
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221222912
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221223936
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221224960
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221225984
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> === IO: pattern 196
+qemu-io> read 512/512 bytes at offset 3221195776
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221196800
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221197824
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221198848
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221199872
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221200896
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221201920
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221202944
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221203968
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221204992
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221206016
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221207040
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221208064
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221209088
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221210112
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221211136
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221212160
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221213184
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221214208
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221215232
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221216256
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221217280
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221218304
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221219328
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221220352
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221221376
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221222400
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221223424
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221224448
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221225472
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221226496
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221227520
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221228544
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221229568
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221230592
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221231616
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221232640
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221233664
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221234688
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221235712
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221236736
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221237760
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221238784
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221239808
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221240832
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221241856
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221242880
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221243904
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221244928
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221245952
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221246976
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221248000
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221249024
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221250048
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221251072
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221252096
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221253120
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221254144
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221255168
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221256192
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221257216
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221258240
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221259264
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> === IO: pattern 0
+qemu-io> read 512/512 bytes at offset 3221228032
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221229056
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221230080
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221231104
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221232128
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221233152
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221234176
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221235200
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221236224
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221237248
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221238272
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221239296
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221240320
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221241344
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221242368
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221243392
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221244416
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221245440
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221246464
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221247488
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221248512
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221249536
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221250560
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221251584
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221252608
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221253632
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221254656
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221255680
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221256704
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221257728
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 512/512 bytes at offset 3221258752
+512.000000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> No errors were found on the image.
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 4c8c4198e4..b9e90f565c 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -34,3 +34,4 @@
 025 rw auto
 026 rw blkdbg auto
 027 rw auto
+028 rw backing auto