iotests: Test blockdev-create in iothread

If blockdev-create references an existing node in an iothread (e.g. as
it's 'file' child), then suddenly all of the image creation code must
run in that AioContext, too. Test that this actually works.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230525124713.401149-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/tests/iothreads-create

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+# group: rw quick
+#
+# Copyright (C) 2023 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>
+
+import asyncio
+import iotests
+
+iotests.script_initialize(supported_fmts=['qcow2', 'qcow', 'qed', 'vdi',
+                                          'vmdk', 'parallels'])
+iotests.verify_virtio_scsi_pci_or_ccw()
+
+with iotests.FilePath('disk.img') as img_path, \
+     iotests.VM() as vm:
+
+    iotests.qemu_img_create('-f', 'raw', img_path, '0')
+
+    vm.add_object('iothread,id=iothread0')
+    vm.add_blockdev(f'file,node-name=img-file,read-only=on,'
+                    f'filename={img_path}')
+    vm.add_device('virtio-scsi,iothread=iothread0')
+    vm.add_device('scsi-hd,drive=img-file,share-rw=on')
+
+    vm.launch()
+
+    iotests.log(vm.qmp(
+        'blockdev-reopen',
+        options=[{
+            'driver': 'file',
+            'filename': img_path,
+            'node-name': 'img-file',
+            'read-only': False,
+        }],
+    ))
+    iotests.log(vm.qmp(
+        'blockdev-create',
+        job_id='job0',
+        options={
+            'driver': iotests.imgfmt,
+            'file': 'img-file',
+            'size': 1024 * 1024,
+        },
+    ))
+
+    # Should succeed and not time out
+    try:
+        vm.run_job('job0', wait=5.0)
+        vm.shutdown()
+    except asyncio.TimeoutError:
+        # VM may be stuck, kill it
+        vm.kill()
+        raise

tests/qemu-iotests/tests/iothreads-create.out

@@ -0,0 +1,4 @@
+{"return": {}}
+{"return": {}}
+{"execute": "job-dismiss", "arguments": {"id": "job0"}}
+{"return": {}}