qemu/tests/qemu-iotests/085
Markus Armbruster c42e8742f5 block: Use JSON null instead of "" to disable backing file
BlockdevRef is an alternate of BlockdevOptions (inline definition) and
str (reference to an existing block device by name).  BlockdevRef
value "" is special: "no block device should be referenced."  It's
actually interpreted that way in just one place: optional member
@backing of COW formats.  Semantics:

* Present means "use this block device" as backing storage

* Absent means "default to the one stored in the image"

* Except "" means "don't use backing storage at all"

The first two are perfectly normal: when the parameter is absent, it
defaults to an implied value, but the value's meaning is the same.

The third one overloads the parameter with a second meaning.  The
overloading is *implicit*, i.e. it's not visible in the types.  Works
here, because "" is not a value block device ID.

Pressing argument values the schema accepts, but are semantically
invalid, into service to mean "do something else entirely" is not
general, as suitable invalid values need not exist.  I also find it
ugly.

To clean this up, we could add a separate flag argument to suppress
@backing, or add a distinct value to @backing.  This commit implements
the latter: add JSON null to the values of @backing, deprecate "".

Because we're so close to the 2.10 freeze, implement it in the
stupidest way possible: have qmp_blockdev_add() rewrite null to ""
before anything else can see the null.  Works, because BlockdevRef
occurs only within arguments of blockdev-add.  The proper way to do it
would be rewriting "" to null, preferably in a cleaner way, but that
requires fixing up code to work with null.  Add a TODO comment for
that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2017-07-24 13:35:11 +02:00

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#!/bin/bash
#
# Live snapshot tests
#
# This tests live snapshots of images on a running QEMU instance, using
# QMP commands. Both single disk snapshots, and transactional group
# snapshots are performed.
#
# Copyright (C) 2014 Red Hat, Inc.
# Copyright (C) 2015 Igalia, S.L.
#
# 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=jcody@redhat.com
seq=`basename $0`
echo "QA output created by $seq"
here=`pwd`
status=1 # failure is the default!
snapshot_virt0="snapshot-v0.qcow2"
snapshot_virt1="snapshot-v1.qcow2"
SNAPSHOTS=10
_cleanup()
{
_cleanup_qemu
for i in $(seq 1 ${SNAPSHOTS})
do
rm -f "${TEST_DIR}/${i}-${snapshot_virt0}"
rm -f "${TEST_DIR}/${i}-${snapshot_virt1}"
done
rm -f "${TEST_IMG}" "${TEST_IMG}.1" "${TEST_IMG}.2" "${TEST_IMG}.base"
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
. ./common.qemu
_supported_fmt qcow2
_supported_proto file
_supported_os Linux
# ${1}: unique identifier for the snapshot filename
function create_single_snapshot()
{
cmd="{ 'execute': 'blockdev-snapshot-sync',
'arguments': { 'device': 'virtio0',
'snapshot-file':'${TEST_DIR}/${1}-${snapshot_virt0}',
'format': 'qcow2' } }"
_send_qemu_cmd $h "${cmd}" "return"
}
# ${1}: unique identifier for the snapshot filename
function create_group_snapshot()
{
cmd="{ 'execute': 'transaction', 'arguments':
{'actions': [
{ 'type': 'blockdev-snapshot-sync', 'data' :
{ 'device': 'virtio0',
'snapshot-file': '${TEST_DIR}/${1}-${snapshot_virt0}' } },
{ 'type': 'blockdev-snapshot-sync', 'data' :
{ 'device': 'virtio1',
'snapshot-file': '${TEST_DIR}/${1}-${snapshot_virt1}' } } ]
} }"
_send_qemu_cmd $h "${cmd}" "return"
}
# ${1}: unique identifier for the snapshot filename
# ${2}: extra_params to the blockdev-add command
# ${3}: filename
function do_blockdev_add()
{
cmd="{ 'execute': 'blockdev-add', 'arguments':
{ 'driver': 'qcow2', 'node-name': 'snap_${1}', ${2}
'file':
{ 'driver': 'file', 'filename': '${3}',
'node-name': 'file_${1}' } } }"
_send_qemu_cmd $h "${cmd}" "return"
}
# ${1}: unique identifier for the snapshot filename
function add_snapshot_image()
{
base_image="${TEST_DIR}/$((${1}-1))-${snapshot_virt0}"
snapshot_file="${TEST_DIR}/${1}-${snapshot_virt0}"
_make_test_img -u -b "${base_image}" "$size"
mv "${TEST_IMG}" "${snapshot_file}"
do_blockdev_add "$1" "'backing': null, " "${snapshot_file}"
}
# ${1}: unique identifier for the snapshot filename
# ${2}: expected response, defaults to 'return'
function blockdev_snapshot()
{
cmd="{ 'execute': 'blockdev-snapshot',
'arguments': { 'node': 'virtio0',
'overlay':'snap_${1}' } }"
_send_qemu_cmd $h "${cmd}" "${2:-return}"
}
size=128M
_make_test_img $size
mv "${TEST_IMG}" "${TEST_IMG}.1"
_make_test_img $size
mv "${TEST_IMG}" "${TEST_IMG}.2"
echo
echo === Running QEMU ===
echo
qemu_comm_method="qmp"
_launch_qemu -drive file="${TEST_IMG}.1",if=virtio -drive file="${TEST_IMG}.2",if=virtio
h=$QEMU_HANDLE
echo
echo === Sending capabilities ===
echo
_send_qemu_cmd $h "{ 'execute': 'qmp_capabilities' }" "return"
# Tests for the blockdev-snapshot-sync command
echo
echo === Create a single snapshot on virtio0 ===
echo
create_single_snapshot 1
echo
echo === Invalid command - missing device and nodename ===
echo
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot-sync',
'arguments': { 'snapshot-file':'${TEST_DIR}/1-${snapshot_virt0}',
'format': 'qcow2' } }" "error"
echo
echo === Invalid command - missing snapshot-file ===
echo
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot-sync',
'arguments': { 'device': 'virtio0',
'format': 'qcow2' } }" "error"
echo
echo
echo === Create several transactional group snapshots ===
echo
for i in $(seq 2 ${SNAPSHOTS})
do
create_group_snapshot ${i}
done
# Tests for the blockdev-snapshot command
echo
echo === Create a couple of snapshots using blockdev-snapshot ===
echo
SNAPSHOTS=$((${SNAPSHOTS}+1))
add_snapshot_image ${SNAPSHOTS}
blockdev_snapshot ${SNAPSHOTS}
SNAPSHOTS=$((${SNAPSHOTS}+1))
add_snapshot_image ${SNAPSHOTS}
blockdev_snapshot ${SNAPSHOTS}
echo
echo === Invalid command - cannot create a snapshot using a file BDS ===
echo
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot',
'arguments': { 'node':'virtio0',
'overlay':'file_${SNAPSHOTS}' }
}" "error"
echo
echo === Invalid command - snapshot node used as active layer ===
echo
blockdev_snapshot ${SNAPSHOTS} error
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot',
'arguments': { 'node':'virtio0',
'overlay':'virtio0' }
}" "error"
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot',
'arguments': { 'node':'virtio0',
'overlay':'virtio1' }
}" "error"
echo
echo === Invalid command - snapshot node used as backing hd ===
echo
blockdev_snapshot $((${SNAPSHOTS}-1)) error
echo
echo === Invalid command - snapshot node has a backing image ===
echo
SNAPSHOTS=$((${SNAPSHOTS}+1))
TEST_IMG="$TEST_IMG.base" _make_test_img "$size"
_make_test_img -b "${TEST_IMG}.base" "$size"
do_blockdev_add ${SNAPSHOTS} "" "${TEST_IMG}"
blockdev_snapshot ${SNAPSHOTS} error
echo
echo === Invalid command - The node does not exist ===
echo
blockdev_snapshot $((${SNAPSHOTS}+1)) error
_send_qemu_cmd $h "{ 'execute': 'blockdev-snapshot',
'arguments': { 'node':'nodevice',
'overlay':'snap_${SNAPSHOTS}' }
}" "error"
# success, all done
echo "*** done"
rm -f $seq.full
status=0