qemu-iotests: Extend non-shared storage migration test (194)

This is the follow-up patch that was discussed[*] as part of feedback to
qemu-iotest 194.

Changes in this patch:

  - Supply 'job-id' parameter to `drive-mirror` invocation.

  - Once migration completes, issue QMP `block-job-cancel` command on
    the source QEMU to gracefully complete `drive-mirror` operation.

  - Once the BLOCK_JOB_COMPLETED event is emitted, stop the NBD server
    on the destination QEMU.

  - Check for both the events: MIGRATION and BLOCK_JOB_COMPLETED.

With the above, the test will also be (almost) in sync with the
procedure outlined in the document 'live-block-operations.rst'[+]
(section: "QMP invocation for live storage migration with
``drive-mirror`` + NBD").

[*] https://lists.nongnu.org/archive/html/qemu-devel/2017-08/msg04820.html
    -- qemu-iotests: add 194 non-shared storage migration test
[+] https://git.qemu.org/gitweb.cgi?p=qemu.git;a=blob;f=docs/interop/live-block-operations.rstSigned-off-by: NKashyap Chamarthy <kchamart@redhat.com>
Message-Id: <20170829165058.8229-1-kchamart@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

tests/qemu-iotests/194

@@ -46,16 +46,17 @@ iotests.log('Launching NBD server on destination...')
 iotests.log(dest_vm.qmp('nbd-server-start', addr={'type': 'unix', 'data': {'path': nbd_sock_path}}))
 iotests.log(dest_vm.qmp('nbd-server-add', device='drive0', writable=True))
 
-iotests.log('Starting drive-mirror on source...')
+iotests.log('Starting `drive-mirror` on source...')
 iotests.log(source_vm.qmp(
               'drive-mirror',
               device='drive0',
               target='nbd+unix:///drive0?socket={0}'.format(nbd_sock_path),
               sync='full',
               format='raw', # always raw, the server handles the format
-              mode='existing'))
+              mode='existing',
+              job_id='mirror-job0'))
 
-iotests.log('Waiting for drive-mirror to complete...')
+iotests.log('Waiting for `drive-mirror` to complete...')
 iotests.log(source_vm.event_wait('BLOCK_JOB_READY'),
             filters=[iotests.filter_qmp_event])
 
@@ -67,7 +68,17 @@ dest_vm.qmp('migrate-set-capabilities',
 iotests.log(source_vm.qmp('migrate', uri='unix:{0}'.format(migration_sock_path)))
 
 while True:
-    event = source_vm.event_wait('MIGRATION')
-    iotests.log(event, filters=[iotests.filter_qmp_event])
-    if event['data']['status'] in ('completed', 'failed'):
+    event1 = source_vm.event_wait('MIGRATION')
+    iotests.log(event1, filters=[iotests.filter_qmp_event])
+    if event1['data']['status'] in ('completed', 'failed'):
+        iotests.log('Gracefully ending the `drive-mirror` job on source...')
+        iotests.log(source_vm.qmp('block-job-cancel', device='mirror-job0'))
+        break
+
+while True:
+    event2 = source_vm.event_wait('BLOCK_JOB_COMPLETED')
+    iotests.log(event2, filters=[iotests.filter_qmp_event])
+    if event2['event'] == 'BLOCK_JOB_COMPLETED':
+        iotests.log('Stopping the NBD server on destination...')
+        iotests.log(dest_vm.qmp('nbd-server-stop'))
         break

tests/qemu-iotests/194.out

@@ -2,12 +2,17 @@ Launching VMs...
 Launching NBD server on destination...
 {u'return': {}}
 {u'return': {}}
-Starting drive-mirror on source...
+Starting `drive-mirror` on source...
 {u'return': {}}
-Waiting for drive-mirror to complete...
-{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'device': u'drive0', u'type': u'mirror', u'speed': 0, u'len': 1073741824, u'offset': 1073741824}, u'event': u'BLOCK_JOB_READY'}
+Waiting for `drive-mirror` to complete...
+{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'device': u'mirror-job0', u'type': u'mirror', u'speed': 0, u'len': 1073741824, u'offset': 1073741824}, u'event': u'BLOCK_JOB_READY'}
 Starting migration...
 {u'return': {}}
 {u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'setup'}, u'event': u'MIGRATION'}
 {u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'active'}, u'event': u'MIGRATION'}
 {u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'status': u'completed'}, u'event': u'MIGRATION'}
+Gracefully ending the `drive-mirror` job on source...
+{u'return': {}}
+{u'timestamp': {u'seconds': 'SECS', u'microseconds': 'USECS'}, u'data': {u'device': u'mirror-job0', u'type': u'mirror', u'speed': 0, u'len': 1073741824, u'offset': 1073741824}, u'event': u'BLOCK_JOB_COMPLETED'}
+Stopping the NBD server on destination...
+{u'return': {}}