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