iotests: Test migration with all kinds of filter nodes

This test case is motivated by commit 2b23f28 ('block/copy-on-read:
Fix permissions for inactive node'). Instead of just testing
copy-on-read on migration, let's stack all sorts of filter nodes on top
of each other and try if the resulting VM can still migrate
successfully. For good measure, put everything into an iothread, because
why not?

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

tests/qemu-iotests/262

@@ -0,0 +1,82 @@
+#!/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 with filter drivers present. Keep everything in an
+# iothread just for fun.
+
+import iotests
+import os
+
+iotests.verify_image_format(supported_fmts=['qcow2'])
+iotests.verify_platform(['linux'])
+
+with iotests.FilePath('img') as img_path, \
+     iotests.FilePath('mig_fifo') as fifo, \
+     iotests.VM(path_suffix='a') as vm_a, \
+     iotests.VM(path_suffix='b') as vm_b:
+
+    def add_opts(vm):
+        vm.add_object('iothread,id=iothread0')
+        vm.add_object('throttle-group,id=tg0,x-bps-total=65536')
+        vm.add_blockdev('file,filename=%s,node-name=drive0-file' % (img_path))
+        vm.add_blockdev('%s,file=drive0-file,node-name=drive0-fmt' % (iotests.imgfmt))
+        vm.add_blockdev('copy-on-read,file=drive0-fmt,node-name=drive0-cor')
+        vm.add_blockdev('throttle,file=drive0-cor,node-name=drive0-throttle,throttle-group=tg0')
+        vm.add_blockdev('blkdebug,image=drive0-throttle,node-name=drive0-dbg')
+        vm.add_blockdev('null-co,node-name=null,read-zeroes=on')
+        vm.add_blockdev('blkverify,test=drive0-dbg,raw=null,node-name=drive0-verify')
+
+        if iotests.supports_quorum():
+            vm.add_blockdev('quorum,children.0=drive0-verify,vote-threshold=1,node-name=drive0-quorum')
+            root = "drive0-quorum"
+        else:
+            root = "drive0-verify"
+
+        vm.add_device('virtio-blk,drive=%s,iothread=iothread0' % root)
+
+    iotests.qemu_img_pipe('create', '-f', iotests.imgfmt, img_path, '64M')
+
+    os.mkfifo(fifo)
+
+    iotests.log('Launching source VM...')
+    add_opts(vm_a)
+    vm_a.launch()
+
+    vm_a.enable_migration_events('A')
+
+    iotests.log('Launching destination VM...')
+    add_opts(vm_b)
+    vm_b.add_incoming("exec: cat '%s'" % (fifo))
+    vm_b.launch()
+
+    vm_b.enable_migration_events('B')
+
+    iotests.log('Starting migration to B...')
+    iotests.log(vm_a.qmp('migrate', uri='exec:cat >%s' % (fifo)))
+    with iotests.Timeout(3, 'Migration does not complete'):
+        # Wait for the source first (which includes setup=setup)
+        vm_a.wait_migration()
+        # Wait for the destination second (which does not)
+        vm_b.wait_migration()
+
+    iotests.log(vm_a.qmp('query-migrate')['return']['status'])
+    iotests.log(vm_b.qmp('query-migrate')['return']['status'])
+
+    iotests.log(vm_a.qmp('query-status'))
+    iotests.log(vm_b.qmp('query-status'))

tests/qemu-iotests/262.out

@@ -0,0 +1,17 @@
+Launching source VM...
+Enabling migration QMP events on A...
+{"return": {}}
+Launching destination VM...
+Enabling migration QMP events on B...
+{"return": {}}
+Starting migration to B...
+{"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"}}
+{"data": {"status": "active"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+{"data": {"status": "completed"}, "event": "MIGRATION", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}
+completed
+completed
+{"return": {"running": false, "singlestep": false, "status": "postmigrate"}}
+{"return": {"running": true, "singlestep": false, "status": "running"}}

tests/qemu-iotests/group

@@ -271,3 +271,4 @@
 254 rw backing quick
 255 rw quick
 256 rw quick
+262 rw quick migration