iotests: Add test 197 for covering copy-on-read

Add a test for qcow2 copy-on-read behavior, including exposure
for the just-fixed bugs.

The copy-on-read behavior is always to a qcow2 image, but the
test is careful to allow running with most image protocol/format
combos as the backing file being copied from (luks being the
exception, as it is harder to pass the right secret to all the
right places).  In fact, for './check nbd', this appears to be
the first time we've had a qcow2 image wrapping NBD, requiring
an additional line in _filter_img_create to match the similar
line in _filter_img_info.

Invoking blkdebug to prove we don't write too much took some
effort to get working; and it requires that $TEST_WRAP (based
on $TEST_DIR) not be subject to word splitting.  We may decide
later to have the entire iotests suite use relative rather than
absolute names, to avoid problems inherited by the absolute
name of $PWD or $TEST_DIR, at which point the sanity check in
this commit could be simplified.

This test requires at least 2G of consecutive memory to succeed;
as such, it is prone to spurious failures, particularly on
32-bit machines under load.  This situation is detected and
triggers an early exit to skip the test, rather than a failure.
To manually provoke this setup on a beefier machine, I used:
  $ (ulimit -S -v 1000000; ./check -qcow2 197)

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Eric Blake 2017-10-05 14:02:48 -05:00 committed by Kevin Wolf
parent cb2e28780c
commit 461743390d
4 changed files with 137 additions and 0 deletions

109
tests/qemu-iotests/197 Executable file
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@ -0,0 +1,109 @@
#!/bin/bash
#
# Test case for copy-on-read into qcow2
#
# Copyright (C) 2017 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=eblake@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
status=1 # failure is the default!
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
TEST_WRAP="$TEST_DIR/t.wrap.qcow2"
BLKDBG_CONF="$TEST_DIR/blkdebug.conf"
# Sanity check: our use of blkdebug fails if $TEST_DIR contains spaces
# or other problems
case "$TEST_DIR" in
*[^-_a-zA-Z0-9/]*)
_notrun "Suspicious TEST_DIR='$TEST_DIR', cowardly refusing to run" ;;
esac
_cleanup()
{
_cleanup_test_img
rm -f "$BLKDBG_CONF"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# Test is supported for any backing file; but we force qcow2 for our wrapper.
_supported_fmt generic
_supported_proto generic
_supported_os Linux
# LUKS support may be possible, but it complicates things.
_unsupported_fmt luks
echo
echo '=== Copy-on-read ==='
echo
# Prep the images
_make_test_img 4G
$QEMU_IO -c "write -P 55 3G 1k" "$TEST_IMG" | _filter_qemu_io
IMGPROTO=file IMGFMT=qcow2 IMGOPTS= TEST_IMG_FILE="$TEST_WRAP" \
_make_test_img -F "$IMGFMT" -b "$TEST_IMG" | _filter_img_create
$QEMU_IO -f qcow2 -c "write -z -u 1M 64k" "$TEST_WRAP" | _filter_qemu_io
# Ensure that a read of two clusters, but where one is already allocated,
# does not re-write the allocated cluster
cat > "$BLKDBG_CONF" <<EOF
[inject-error]
event = "cor_write"
sector = "2048"
EOF
$QEMU_IO -c "open -C \
-o driver=blkdebug,config=$BLKDBG_CONF,image.driver=qcow2 $TEST_WRAP" \
-c "read -P 0 1M 128k" | _filter_qemu_io
# Read the areas we want copied. A zero-length read should still be a
# no-op. The next read is under 2G, but aligned so that rounding to
# clusters copies more than 2G of zeroes. The final read will pick up
# the non-zero data in the same cluster. Since a 2G read may exhaust
# memory on some machines (particularly 32-bit), we skip the test if
# that fails due to memory pressure.
$QEMU_IO -f qcow2 -C -c "read 0 0" "$TEST_WRAP" | _filter_qemu_io
output=$($QEMU_IO -f qcow2 -C -c "read -P 0 1k $((2*1024*1024*1024 - 512))" \
"$TEST_WRAP" 2>&1 | _filter_qemu_io)
case $output in
*allocate*)
_notrun "Insufficent memory to run test" ;;
*) printf '%s\n' "$output" ;;
esac
$QEMU_IO -f qcow2 -C -c "read -P 0 $((3*1024*1024*1024 + 1024)) 1k" \
"$TEST_WRAP" | _filter_qemu_io
# Copy-on-read is incompatible with read-only
$QEMU_IO -f qcow2 -C -r "$TEST_WRAP" 2>&1 | _filter_testdir
# Break the backing chain, and show that images are identical, and that
# we properly copied over explicit zeros.
$QEMU_IMG rebase -u -b "" -f qcow2 "$TEST_WRAP"
$QEMU_IO -f qcow2 -c map "$TEST_WRAP"
_check_test_img
$QEMU_IMG compare -f $IMGFMT -F qcow2 "$TEST_IMG" "$TEST_WRAP"
# success, all done
echo '*** done'
status=0

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QA output created by 197
=== Copy-on-read ===
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=4294967296
wrote 1024/1024 bytes at offset 3221225472
1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
Formatting 'TEST_DIR/t.wrap.IMGFMT', fmt=IMGFMT size=4294967296 backing_file=TEST_DIR/t.IMGFMT backing_fmt=IMGFMT
wrote 65536/65536 bytes at offset 1048576
64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 131072/131072 bytes at offset 1048576
128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 0/0 bytes at offset 0
0 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 2147483136/2147483136 bytes at offset 1024
2 GiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 1024/1024 bytes at offset 3221226496
1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
can't open device TEST_DIR/t.wrap.qcow2: Can't use copy-on-read on read-only device
2 GiB (0x80010000) bytes allocated at offset 0 bytes (0x0)
1023.938 MiB (0x3fff0000) bytes not allocated at offset 2 GiB (0x80010000)
64 KiB (0x10000) bytes allocated at offset 3 GiB (0xc0000000)
1023.938 MiB (0x3fff0000) bytes not allocated at offset 3 GiB (0xc0010000)
No errors were found on the image.
Images are identical.
*** done

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@ -111,6 +111,7 @@ _filter_img_create()
sed -e "s#$IMGPROTO:$TEST_DIR#TEST_DIR#g" \
-e "s#$TEST_DIR#TEST_DIR#g" \
-e "s#$IMGFMT#IMGFMT#g" \
-e 's#nbd:127.0.0.1:10810#TEST_DIR/t.IMGFMT#g' \
-e "s# encryption=off##g" \
-e "s# cluster_size=[0-9]\\+##g" \
-e "s# table_size=[0-9]\\+##g" \

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@ -192,3 +192,4 @@
192 rw auto quick
194 rw auto migration quick
195 rw auto quick
197 rw auto quick