iotests: Test external snapshot with VM state

This tests creating an external snapshot with VM state (which results in
an active overlay over an inactive backing file, which is also the root
node of an inactive BlockBackend), re-activating the images and
performing some operations to test that the re-activation worked as
intended.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/280

@@ -0,0 +1,83 @@
+#!/usr/bin/env python
+#
+# Copyright (C) 2019 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: Kevin Wolf <kwolf@redhat.com>
+#
+# Test migration to file for taking an external snapshot with VM state.
+
+import iotests
+import os
+
+iotests.verify_image_format(supported_fmts=['qcow2'])
+iotests.verify_protocol(supported=['file'])
+iotests.verify_platform(['linux'])
+
+with iotests.FilePath('base') as base_path , \
+     iotests.FilePath('top') as top_path, \
+     iotests.VM() as vm:
+
+    iotests.qemu_img_log('create', '-f', iotests.imgfmt, base_path, '64M')
+
+    iotests.log('=== Launch VM ===')
+    vm.add_object('iothread,id=iothread0')
+    vm.add_blockdev('file,filename=%s,node-name=base-file' % (base_path))
+    vm.add_blockdev('%s,file=base-file,node-name=base-fmt' % (iotests.imgfmt))
+    vm.add_device('virtio-blk,drive=base-fmt,iothread=iothread0,id=vda')
+    vm.launch()
+
+    vm.enable_migration_events('VM')
+
+    iotests.log('\n=== Migrate to file ===')
+    vm.qmp_log('migrate', uri='exec:cat > /dev/null')
+
+    with iotests.Timeout(3, 'Migration does not complete'):
+        vm.wait_migration()
+
+    iotests.log('\nVM is now stopped:')
+    iotests.log(vm.qmp('query-migrate')['return']['status'])
+    vm.qmp_log('query-status')
+
+    iotests.log('\n=== Create a snapshot of the disk image ===')
+    vm.blockdev_create({
+        'driver': 'file',
+        'filename': top_path,
+        'size': 0,
+    })
+    vm.qmp_log('blockdev-add', node_name='top-file',
+               driver='file', filename=top_path,
+               filters=[iotests.filter_qmp_testfiles])
+
+    vm.blockdev_create({
+        'driver': iotests.imgfmt,
+        'file': 'top-file',
+        'size': 1024 * 1024,
+    })
+    vm.qmp_log('blockdev-add', node_name='top-fmt',
+               driver=iotests.imgfmt, file='top-file')
+
+    vm.qmp_log('blockdev-snapshot', node='base-fmt', overlay='top-fmt')
+
+    iotests.log('\n=== Resume the VM and simulate a write request ===')
+    vm.qmp_log('cont')
+    iotests.log(vm.hmp_qemu_io('-d vda/virtio-backend', 'write 4k 4k'))
+
+    iotests.log('\n=== Commit it to the backing file ===')
+    result = vm.qmp_log('block-commit', job_id='job0', auto_dismiss=False,
+                        device='top-fmt', top_node='top-fmt',
+                        filters=[iotests.filter_qmp_testfiles])
+    if 'return' in result:
+        vm.run_job('job0')

tests/qemu-iotests/280.out

@@ -0,0 +1,50 @@
+Formatting 'TEST_DIR/PID-base', fmt=qcow2 size=67108864 cluster_size=65536 lazy_refcounts=off refcount_bits=16
+
+=== Launch VM ===
+Enabling migration QMP events on VM...
+{"return": {}}
+
+=== Migrate to file ===
+{"execute": "migrate", "arguments": {"uri": "exec:cat > /dev/null"}}
+{"return": {}}
+{"data": {"status": "setup"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"status": "active"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"status": "completed"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+
+VM is now stopped:
+completed
+{"execute": "query-status", "arguments": {}}
+{"return": {"running": false, "singlestep": false, "status": "postmigrate"}}
+
+=== Create a snapshot of the disk image ===
+{"execute": "blockdev-create", "arguments": {"job-id": "job0", "options": {"driver": "file", "filename": "TEST_DIR/PID-top", "size": 0}}}
+{"return": {}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}
+
+{"execute": "blockdev-add", "arguments": {"driver": "file", "filename": "TEST_DIR/PID-top", "node-name": "top-file"}}
+{"return": {}}
+{"execute": "blockdev-create", "arguments": {"job-id": "job0", "options": {"driver": "qcow2", "file": "top-file", "size": 1048576}}}
+{"return": {}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}
+
+{"execute": "blockdev-add", "arguments": {"driver": "qcow2", "file": "top-file", "node-name": "top-fmt"}}
+{"return": {}}
+{"execute": "blockdev-snapshot", "arguments": {"node": "base-fmt", "overlay": "top-fmt"}}
+{"return": {}}
+
+=== Resume the VM and simulate a write request ===
+{"execute": "cont", "arguments": {}}
+{"return": {}}
+{"return": ""}
+
+=== Commit it to the backing file ===
+{"execute": "block-commit", "arguments": {"auto-dismiss": false, "device": "top-fmt", "job-id": "job0", "top-node": "top-fmt"}}
+{"return": {}}
+{"execute": "job-complete", "arguments": {"id": "job0"}}
+{"return": {}}
+{"data": {"device": "job0", "len": 65536, "offset": 65536, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_READY", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"device": "job0", "len": 65536, "offset": 65536, "speed": 0, "type": "commit"}, "event": "BLOCK_JOB_COMPLETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}

tests/qemu-iotests/group

@@ -287,3 +287,4 @@
 273 backing quick
 277 rw quick
 279 rw backing quick
+280 rw migration quick