iotests: add test for removing persistent bitmap from backing file

Just demonstrate one of x-blockdev-reopen usecases. We can't simply
remove persistent bitmap from RO node (for example from backing file),
as we need to remove it from the image too. So, we should reopen the
node first.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210401161522.8001-1-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qemu-iotests/tests/remove-bitmap-from-backing

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+#
+# Test removing persistent bitmap from backing
+#
+# Copyright (c) 2021 Virtuozzo International GmbH.
+#
+# 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/>.
+#
+
+import iotests
+from iotests import log, qemu_img_create, qemu_img, qemu_img_pipe
+
+iotests.script_initialize(supported_fmts=['qcow2'])
+
+top, base = iotests.file_path('top', 'base')
+size = '1M'
+
+assert qemu_img_create('-f', iotests.imgfmt, base, size) == 0
+assert qemu_img_create('-f', iotests.imgfmt, '-b', base,
+                       '-F', iotests.imgfmt, top, size) == 0
+
+assert qemu_img('bitmap', '--add', base, 'bitmap0') == 0
+# Just assert that our method of checking bitmaps in the image works.
+assert 'bitmaps' in qemu_img_pipe('info', base)
+
+vm = iotests.VM().add_drive(top, 'backing.node-name=base')
+vm.launch()
+
+log('Trying to remove persistent bitmap from r-o base node, should fail:')
+vm.qmp_log('block-dirty-bitmap-remove', node='base', name='bitmap0')
+
+new_base_opts = {
+    'node-name': 'base',
+    'driver': 'qcow2',
+    'file': {
+        'driver': 'file',
+        'filename':  base
+    },
+    'read-only': False
+}
+
+# Don't want to bother with filtering qmp_log for reopen command
+result = vm.qmp('x-blockdev-reopen', **new_base_opts)
+if result != {'return': {}}:
+    log('Failed to reopen: ' + str(result))
+
+log('Remove persistent bitmap from base node reopened to RW:')
+vm.qmp_log('block-dirty-bitmap-remove', node='base', name='bitmap0')
+
+new_base_opts['read-only'] = True
+result = vm.qmp('x-blockdev-reopen', **new_base_opts)
+if result != {'return': {}}:
+    log('Failed to reopen: ' + str(result))
+
+vm.shutdown()
+
+if 'bitmaps' in qemu_img_pipe('info', base):
+    log('ERROR: Bitmap is still in the base image')

tests/qemu-iotests/tests/remove-bitmap-from-backing.out

@@ -0,0 +1,6 @@
+Trying to remove persistent bitmap from r-o base node, should fail:
+{"execute": "block-dirty-bitmap-remove", "arguments": {"name": "bitmap0", "node": "base"}}
+{"error": {"class": "GenericError", "desc": "Bitmap 'bitmap0' is readonly and cannot be modified"}}
+Remove persistent bitmap from base node reopened to RW:
+{"execute": "block-dirty-bitmap-remove", "arguments": {"name": "bitmap0", "node": "base"}}
+{"return": {}}