From 27042ff7aca4366c50e8ed66b47487d46774d16a Mon Sep 17 00:00:00 2001
From: Hanna Reitz <hreitz@redhat.com>
Date: Wed, 16 Feb 2022 11:53:55 +0100
Subject: [PATCH 24/24] iotests/graph-changes-while-io: New test
RH-Author: Hanna Reitz <hreitz@redhat.com>
RH-MergeRequest: 189: block: Make bdrv_refresh_limits() non-recursive
RH-Commit: [3/3] b9dffe09bef6cf9b2f0aad69b327ea1df92e847a
RH-Bugzilla: 2072932
RH-Acked-by: Eric Blake <eblake@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
Test the following scenario:
1. Some block node (null-co) attached to a user (here: NBD server) that
performs I/O and keeps the node in an I/O thread
2. Repeatedly run blockdev-add/blockdev-del to add/remove an overlay
to/from that node
Each blockdev-add triggers bdrv_refresh_limits(), and because
blockdev-add runs in the main thread, it does not stop the I/O requests.
I/O can thus happen while the limits are refreshed, and when such a
request sees a temporarily invalid block limit (e.g. alignment is 0),
this may easily crash qemu (or the storage daemon in this case).
The block layer needs to ensure that I/O requests to a node are paused
while that node's BlockLimits are refreshed.
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220216105355.30729-4-hreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 971bea8089531af56b1bbd9ce62e756bdf006711)
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
---
.../qemu-iotests/tests/graph-changes-while-io | 91 +++++++++++++++++++
.../tests/graph-changes-while-io.out | 5 +
2 files changed, 96 insertions(+)
create mode 100755 tests/qemu-iotests/tests/graph-changes-while-io
create mode 100644 tests/qemu-iotests/tests/graph-changes-while-io.out
diff --git a/tests/qemu-iotests/tests/graph-changes-while-io b/tests/qemu-iotests/tests/graph-changes-while-io
new file mode 100755
index 0000000000..567e8cf21e
--- /dev/null
+++ b/tests/qemu-iotests/tests/graph-changes-while-io
@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+# group: rw
+#
+# Test graph changes while I/O is happening
+#
+# Copyright (C) 2022 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/>.
+#
+
+import os
+from threading import Thread
+import iotests
+from iotests import imgfmt, qemu_img, qemu_img_create, QMPTestCase, \
+ QemuStorageDaemon
+
+
+top = os.path.join(iotests.test_dir, 'top.img')
+nbd_sock = os.path.join(iotests.sock_dir, 'nbd.sock')
+
+
+def do_qemu_img_bench() -> None:
+ """
+ Do some I/O requests on `nbd_sock`.
+ """
+ assert qemu_img('bench', '-f', 'raw', '-c', '2000000',
+ f'nbd+unix:///node0?socket={nbd_sock}') == 0
+
+
+class TestGraphChangesWhileIO(QMPTestCase):
+ def setUp(self) -> None:
+ # Create an overlay that can be added at runtime on top of the
+ # null-co block node that will receive I/O
+ assert qemu_img_create('-f', imgfmt, '-F', 'raw', '-b', 'null-co://',
+ top) == 0
+
+ # QSD instance with a null-co block node in an I/O thread,
+ # exported over NBD (on `nbd_sock`, export name "node0")
+ self.qsd = QemuStorageDaemon(
+ '--object', 'iothread,id=iothread0',
+ '--blockdev', 'null-co,node-name=node0,read-zeroes=true',
+ '--nbd-server', f'addr.type=unix,addr.path={nbd_sock}',
+ '--export', 'nbd,id=exp0,node-name=node0,iothread=iothread0,' +
+ 'fixed-iothread=true,writable=true',
+ qmp=True
+ )
+
+ def tearDown(self) -> None:
+ self.qsd.stop()
+
+ def test_blockdev_add_while_io(self) -> None:
+ # Run qemu-img bench in the background
+ bench_thr = Thread(target=do_qemu_img_bench)
+ bench_thr.start()
+
+ # While qemu-img bench is running, repeatedly add and remove an
+ # overlay to/from node0
+ while bench_thr.is_alive():
+ result = self.qsd.qmp('blockdev-add', {
+ 'driver': imgfmt,
+ 'node-name': 'overlay',
+ 'backing': 'node0',
+ 'file': {
+ 'driver': 'file',
+ 'filename': top
+ }
+ })
+ self.assert_qmp(result, 'return', {})
+
+ result = self.qsd.qmp('blockdev-del', {
+ 'node-name': 'overlay'
+ })
+ self.assert_qmp(result, 'return', {})
+
+ bench_thr.join()
+
+if __name__ == '__main__':
+ # Format must support raw backing files
+ iotests.main(supported_fmts=['qcow', 'qcow2', 'qed'],
+ supported_protocols=['file'])
diff --git a/tests/qemu-iotests/tests/graph-changes-while-io.out b/tests/qemu-iotests/tests/graph-changes-while-io.out
new file mode 100644
index 0000000000..ae1213e6f8
--- /dev/null
+++ b/tests/qemu-iotests/tests/graph-changes-while-io.out
@@ -0,0 +1,5 @@
+.
+----------------------------------------------------------------------
+Ran 1 tests
+
+OK
--
2.35.3