[PATCH v9 4/3] iotests: test nbd reconnect

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Add test, which starts backup to nbd target and restarts nbd server
during backup.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---

Updated test: avoid race conditions + some improvements.
  - introduce qemu_io_silent_check and use it to wait for NBD server
  start
  - use size variable instead of '5M' in all places
  - use smart waiting loop instead of sleep, to wait for job progress
  - do srv.wait() after srv.kill(), to be sure that server is stopped
  - drop throttling earlier

  Now, test lasts 3 seconds for me. If it is wrong for you,
  be free to drop 'quick' tag.

 tests/qemu-iotests/264        | 95 +++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/264.out    | 13 +++++
 tests/qemu-iotests/group      |  1 +
 tests/qemu-iotests/iotests.py | 11 ++++
 4 files changed, 120 insertions(+)
 create mode 100755 tests/qemu-iotests/264
 create mode 100644 tests/qemu-iotests/264.out

diff --git a/tests/qemu-iotests/264 b/tests/qemu-iotests/264
new file mode 100755
index 0000000000..c8cd97ae2b
--- /dev/null
+++ b/tests/qemu-iotests/264
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+#
+# Test nbd reconnect
+#
+# Copyright (c) 2019 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 time
+
+import iotests
+from iotests import qemu_img_create, qemu_io_silent_check, file_path, \
+        qemu_nbd_popen, log
+
+disk_a, disk_b, nbd_sock = file_path('disk_a', 'disk_b', 'nbd-sock')
+nbd_uri = 'nbd+unix:///?socket=' + nbd_sock
+size = 5 * 1024 * 1024
+wait_limit = 3
+wait_step = 0.2
+
+qemu_img_create('-f', iotests.imgfmt, disk_a, str(size))
+qemu_img_create('-f', iotests.imgfmt, disk_b, str(size))
+srv = qemu_nbd_popen('-k', nbd_sock, '-f', iotests.imgfmt, disk_b)
+
+# Wait for NBD server availability
+t = 0
+ok = False
+while t < wait_limit:
+    ok = qemu_io_silent_check('-f', 'raw', '-c', 'read 0 512', nbd_uri)
+    if ok:
+        break
+    time.sleep(wait_step)
+    t += wait_step
+
+assert ok
+
+vm = iotests.VM().add_drive(disk_a)
+vm.launch()
+vm.hmp_qemu_io('drive0', 'write 0 {}'.format(size))
+
+vm.qmp_log('blockdev-add', filters=[iotests.filter_qmp_testfiles],
+           **{'node_name': 'backup0',
+              'driver': 'raw',
+              'file': {'driver': 'nbd',
+                       'server': {'type': 'unix', 'path': nbd_sock},
+                       'reconnect-delay': 10}})
+vm.qmp_log('blockdev-backup', device='drive0', sync='full', target='backup0',
+           speed=(1 * 1024 * 1024))
+
+# Wait for some progress
+t = 0
+while t < wait_limit:
+    jobs = vm.qmp('query-block-jobs')['return']
+    if jobs and jobs[0]['offset'] > 0:
+        break
+    time.sleep(wait_step)
+    t += wait_step
+
+if jobs and jobs[0]['offset'] > 0:
+    log('Backup job is started')
+
+log('Kill NBD server')
+srv.kill()
+srv.wait()
+
+jobs = vm.qmp('query-block-jobs')['return']
+if jobs and jobs[0]['offset'] < jobs[0]['len']:
+    log('Backup job is still in progress')
+
+vm.qmp_log('block-job-set-speed', device='drive0', speed=0)
+
+# Emulate server down time for 1 second
+time.sleep(1)
+
+log('Start NBD server')
+srv = qemu_nbd_popen('-k', nbd_sock, '-f', iotests.imgfmt, disk_b)
+
+e = vm.event_wait('BLOCK_JOB_COMPLETED')
+log('Backup completed: {}'.format(e['data']['offset']))
+
+vm.qmp_log('blockdev-del', node_name='backup0')
+srv.kill()
+vm.shutdown()
diff --git a/tests/qemu-iotests/264.out b/tests/qemu-iotests/264.out
new file mode 100644
index 0000000000..3000944b09
--- /dev/null
+++ b/tests/qemu-iotests/264.out
@@ -0,0 +1,13 @@
+{"execute": "blockdev-add", "arguments": {"driver": "raw", "file": {"driver": "nbd", "reconnect-delay": 10, "server": {"path": "TEST_DIR/PID-nbd-sock", "type": "unix"}}, "node-name": "backup0"}}
+{"return": {}}
+{"execute": "blockdev-backup", "arguments": {"device": "drive0", "speed": 1048576, "sync": "full", "target": "backup0"}}
+{"return": {}}
+Backup job is started
+Kill NBD server
+Backup job is still in progress
+{"execute": "block-job-set-speed", "arguments": {"device": "drive0", "speed": 0}}
+{"return": {}}
+Start NBD server
+Backup completed: 5242880
+{"execute": "blockdev-del", "arguments": {"node-name": "backup0"}}
+{"return": {}}
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 5d3da937e4..4f6dd6f153 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -275,5 +275,6 @@
 258 rw quick
 262 rw quick migration
 263 rw quick
+264 rw quick
 265 rw auto quick
 266 rw quick
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index b26271187c..8912bd4661 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -164,6 +164,13 @@ def qemu_io_silent(*args):
                          (-exitcode, ' '.join(args)))
     return exitcode
 
+def qemu_io_silent_check(*args):
+    '''Run qemu-io and return the true if subprocess returned 0'''
+    args = qemu_io_args + list(args)
+    exitcode = subprocess.call(args, stdout=open('/dev/null', 'w'),
+                               stderr=subprocess.STDOUT)
+    return exitcode == 0
+
 def get_virtio_scsi_device():
     if qemu_default_machine == 's390-ccw-virtio':
         return 'virtio-scsi-ccw'
@@ -229,6 +236,10 @@ def qemu_nbd_early_pipe(*args):
     else:
         return exitcode, subp.communicate()[0]
 
+def qemu_nbd_popen(*args):
+    '''Run qemu-nbd in daemon mode and return the parent's exit code'''
+    return subprocess.Popen(qemu_nbd_args + ['--persistent'] + list(args))
+
 def compare_images(img1, img2, fmt1=imgfmt, fmt2=imgfmt):
     '''Return True if two image files are identical'''
     return qemu_img('compare', '-f', fmt1,
-- 
2.21.0