Re: [Qemu-devel] [PATCH 7/6] qemu-iotests: Test change-backing-file command

[Eric Blake]

On 09/15/2017 12:02 PM, Kevin Wolf wrote:
> This involves a temporary read-write reopen if the backing file link in
> the middle of a backing file chain should be changed and is therefore a
> good test for the latest bdrv_reopen() vs. op blockers fixes.
> 
> Signed-off-by: Kevin Wolf 
> ---
> 
> I actually managed to find a simple case that reproduces the bug that
> is fixed in this series, but outside of my commit job improvements that
> originally led me to this work.
> 
>  tests/qemu-iotests/195 | 92 
> ++
>  tests/qemu-iotests/195.out | 78 +++
>  tests/qemu-iotests/group   |  1 +

The usual collision in test numbering ;)


> +_cleanup()
> +{
> +_cleanup_test_img
> +rm -f "$TEST_IMG.mid"
> +}
> +trap "_cleanup; exit \$status" 0 1 2 3 15

Semantic conflict with Jeff's work to add './check -s' to save
intermediate files in a per-test temp directory.

> +
> +echo
> +echo "Change backing file of mid (opened read-only)"
> +echo
> +
> +run_qemu -drive if=none,file="$TEST_IMG",backing.node-name=mid < +{"execute":"qmp_capabilities"}
> +{"execute":"change-backing-file", 
> "arguments":{"device":"none0","image-node-name":"mid","backing-file":"/dev/null"}}

Since the images don't contain any content, I guess this works.  But
another possible change would be rewriting the backing file to alternate
between absolute and relative (or even between 'file' and './file') (so
that it's pointing to the same file at all times, just by different names)

> +{"execute":"quit"}
> +EOF
> +
> +TEST_IMG="$TEST_IMG.mid" _img_info
> +
> +echo
> +echo "Change backing file of top (opened writable)"
> +echo
> +
> +TEST_IMG="$TEST_IMG.mid" _make_test_img -b "$TEST_IMG.base"
> +
> +run_qemu -drive if=none,file="$TEST_IMG",node-name=top < +{"execute":"qmp_capabilities"}
> +{"execute":"change-backing-file", 
> "arguments":{"device":"none0","image-node-name":"top","backing-file":"/dev/null"}}
> +{"execute":"quit"}

You've quit qemu between runs.  Would we get any further coverage by doing:

change mid
change active
change mid

all within a single run? (That is, make SURE that actions on one part of
the graph don't interfere with later actions elsewhere)

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.   +1-919-301-3266
Virtualization:  qemu.org | libvirt.org



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[Qemu-devel] [PATCH 7/6] qemu-iotests: Test change-backing-file command

[Kevin Wolf]

This involves a temporary read-write reopen if the backing file link in
the middle of a backing file chain should be changed and is therefore a
good test for the latest bdrv_reopen() vs. op blockers fixes.

Signed-off-by: Kevin Wolf 
---

I actually managed to find a simple case that reproduces the bug that
is fixed in this series, but outside of my commit job improvements that
originally led me to this work.

 tests/qemu-iotests/195 | 92 ++
 tests/qemu-iotests/195.out | 78 +++
 tests/qemu-iotests/group   |  1 +
 3 files changed, 171 insertions(+)
 create mode 100755 tests/qemu-iotests/195
 create mode 100644 tests/qemu-iotests/195.out

diff --git a/tests/qemu-iotests/195 b/tests/qemu-iotests/195
new file mode 100755
index 00..05a239cbf5
--- /dev/null
+++ b/tests/qemu-iotests/195
@@ -0,0 +1,92 @@
+#!/bin/bash
+#
+# Test change-backing-file command
+#
+# 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 .
+#
+
+# creator
+owner=kw...@redhat.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1 # failure is the default!
+
+_cleanup()
+{
+_cleanup_test_img
+rm -f "$TEST_IMG.mid"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+function do_run_qemu()
+{
+echo Testing: "$@" | _filter_imgfmt
+$QEMU -nographic -qmp-pretty stdio -serial none "$@"
+echo
+}
+
+function run_qemu()
+{
+do_run_qemu "$@" 2>&1 | _filter_testdir | _filter_qemu | _filter_qmp \
+  | _filter_qemu_io | _filter_generated_node_ids
+}
+
+size=64M
+TEST_IMG="$TEST_IMG.base" _make_test_img $size
+TEST_IMG="$TEST_IMG.mid" _make_test_img -b "$TEST_IMG.base"
+_make_test_img -b "$TEST_IMG.mid"
+
+echo
+echo "Change backing file of mid (opened read-only)"
+echo
+
+run_qemu -drive if=none,file="$TEST_IMG",backing.node-name=mid <