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NVMe-oF: Return right nqn when missing hostnqn

This patch fixes a problem where we don't return the right nqn value
when the /etc/nvme/hostnqn file doesn't exist.

Currently get_connector_properties returns a new nqn value every time it
gets called if the hostnqn file is not present in the system.

The reason for this is that we are calling "nvme gen-hostnqn" and piping
it to tee, but for some reason tee is failing to write the file, so on
each call we'll generate a new nqn.

Even if we were successfully creating the hostnqn file, that could
create problems if we have already attached some volumes, since those
would have used the existing nqn.

This patch replaces the series of command executions (mkdir, nvme,
chmod) with a privsep method that then leverages the equivalent python
methods when possible and also tries to use the show-hostnqn nvme
subcommand first to get the existing nqn before defaulting to generating
a new one with gen-hostnqn.  This way we don't replace the current nqn
value that may be already being used by other nvme connections.

Subcommand show-hostnqn returns the host NQN configured for the system.
First looks for /etc/nvme/hostnqn, if it's not present (our case when we
call the new create_hostnqn method) tries to construct it from dmi
(/sys/firmware/dmi/entries) or from systemd's application-specific
machine IDs for the system [1].

It's important to differentiate between the ENOENT returned as OSError
and the same value returned by nvme [2] when show-hostnqn cannot return
anything.

[1]: ed9538622a/fabrics.c (L858-L875)
[2]: 5b8b065b1d/nvme.c (L5642-L5643)

Closes-Bug: #1928944
Change-Id: I252dd958767dcdd4f9a2767b362aaf675edb79c4
changes/37/792237/2
Gorka Eguileor 4 months ago
parent
commit
37d57c4306
  1. 20
      os_brick/initiator/connectors/nvmeof.py
  2. 66
      os_brick/privileged/nvmeof.py
  3. 20
      os_brick/tests/initiator/connectors/test_nvmeof.py
  4. 97
      os_brick/tests/privileged/test_nvmeof.py
  5. 7
      releasenotes/notes/nvme-hostnqn-c2611dc56729183b.yaml

20
os_brick/initiator/connectors/nvmeof.py

@ -28,6 +28,7 @@ try:
from os_brick.initiator.connectors import nvmeof_agent
except ImportError:
nvmeof_agent = None
from os_brick.privileged import nvmeof as priv_nvme
from os_brick.privileged import rootwrap as priv_rootwrap
from os_brick import utils
@ -128,26 +129,13 @@ class NVMeOFConnector(base.BaseLinuxConnector):
return None
def _get_host_nqn(self):
host_nqn = None
try:
with open('/etc/nvme/hostnqn', 'r') as f:
host_nqn = f.read().strip()
f.close()
except IOError:
try:
self._execute(
'mkdir', '-m', '755', '-p', '/etc/nvme',
root_helper=self._root_helper, run_as_root=True)
out, err = self._execute(
'nvme', 'gen-hostnqn', '|', 'tee', '/etc/nvme/hostnqn',
root_helper=self._root_helper, run_as_root=True)
if out.strip():
host_nqn = out.strip()
self._execute(
'chmod', '644', '/etc/nvme/hostnqn',
root_helper=self._root_helper, run_as_root=True)
except Exception as e:
LOG.warning("Could not generate host nqn: %s" % str(e))
host_nqn = priv_nvme.create_hostnqn()
except Exception:
host_nqn = None
return host_nqn
def _get_system_uuid(self):

66
os_brick/privileged/nvmeof.py

@ -0,0 +1,66 @@
# Copyright (c) 2021, Red Hat, Inc.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import errno
import os
from oslo_concurrency import processutils as putils
from oslo_log import log as logging
import os_brick.privileged
from os_brick.privileged import rootwrap
LOG = logging.getLogger(__name__)
@os_brick.privileged.default.entrypoint
def create_hostnqn():
"""Create the hostnqn file to speed up finding out the nqn.
By having the /etc/nvme/hostnqn not only do we make sure that that value is
always used on this system, but we are also able to just open the file to
get the nqn on each get_connector_properties call instead of having to make
a call to nvme show-hostnqn command.
"""
host_nqn = ''
try:
os.makedirs('/etc/nvme', mode=0o755, exist_ok=True)
# Try to get existing nqn generated from dmi or systemd
try:
host_nqn, err = rootwrap.custom_execute('nvme', 'show-hostnqn')
host_nqn = host_nqn.strip()
# This is different from OSError's ENOENT, which is missing nvme
# command. This ENOENT is when nvme says there isn't an nqn.
except putils.ProcessExecutionError as e:
if e.exit_code != errno.ENOENT:
raise
LOG.debug('No nqn could be formed from dmi or systemd.')
if not host_nqn:
LOG.debug('Generating nqn')
host_nqn, err = rootwrap.custom_execute('nvme', 'gen-hostnqn')
host_nqn = host_nqn.strip()
with open('/etc/nvme/hostnqn', 'w') as f:
LOG.debug('Writing hostnqn file')
f.write(host_nqn)
os.chmod('/etc/nvme/hostnqn', 0o644)
except Exception as e:
LOG.warning("Could not generate host nqn: %s" % str(e))
return host_nqn

20
os_brick/tests/initiator/connectors/test_nvmeof.py

@ -882,14 +882,26 @@ class NVMeOFConnectorTestCase(test_connector.ConnectorTestCase):
mock_open.return_value.__enter__.return_value.read = (
lambda: HOST_NQN + "\n")
host_nqn = self._get_host_nqn()
self.assertEqual(host_nqn, HOST_NQN)
mock_open.assert_called_once_with('/etc/nvme/hostnqn', 'r')
self.assertEqual(HOST_NQN, host_nqn)
@mock.patch.object(executor.Executor, '_execute')
@mock.patch.object(nvmeof.priv_nvme, 'create_hostnqn')
@mock.patch.object(builtins, 'open')
def test_get_host_nqn_err(self, mock_open, mock_execute):
mock_execute.side_effect = Exception()
def test_get_host_nqn_io_err(self, mock_open, mock_create):
mock_create.return_value = mock.sentinel.nqn
mock_open.side_effect = IOError()
result = self.connector._get_host_nqn()
mock_open.assert_called_once_with('/etc/nvme/hostnqn', 'r')
mock_create.assert_called_once_with()
self.assertEqual(mock.sentinel.nqn, result)
@mock.patch.object(nvmeof.priv_nvme, 'create_hostnqn')
@mock.patch.object(builtins, 'open')
def test_get_host_nqn_err(self, mock_open, mock_create):
mock_open.side_effect = Exception()
result = self.connector._get_host_nqn()
mock_open.assert_called_once_with('/etc/nvme/hostnqn', 'r')
mock_create.assert_not_called()
self.assertIsNone(result)
@mock.patch.object(executor.Executor, '_execute')

97
os_brick/tests/privileged/test_nvmeof.py

@ -0,0 +1,97 @@
# Copyright (c) 2021, Red Hat, Inc.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import builtins
import errno
from unittest import mock
import ddt
from oslo_concurrency import processutils as putils
import os_brick.privileged as privsep_brick
import os_brick.privileged.nvmeof as privsep_nvme
from os_brick.privileged import rootwrap
from os_brick.tests import base
@ddt.ddt
class PrivNVMeTestCase(base.TestCase):
def setUp(self):
super(PrivNVMeTestCase, self).setUp()
# Disable privsep server/client mode
privsep_brick.default.set_client_mode(False)
self.addCleanup(privsep_brick.default.set_client_mode, True)
@mock.patch('os.chmod')
@mock.patch.object(builtins, 'open', new_callable=mock.mock_open)
@mock.patch('os.makedirs')
@mock.patch.object(rootwrap, 'custom_execute')
def test_create_hostnqn(self, mock_exec, mock_mkdirs, mock_open,
mock_chmod):
hostnqn = mock.Mock()
mock_exec.return_value = (hostnqn, mock.sentinel.err)
res = privsep_nvme.create_hostnqn()
mock_mkdirs.assert_called_once_with('/etc/nvme',
mode=0o755,
exist_ok=True)
mock_exec.assert_called_once_with('nvme', 'show-hostnqn')
mock_open.assert_called_once_with('/etc/nvme/hostnqn', 'w')
stripped_hostnqn = hostnqn.strip.return_value
mock_open().write.assert_called_once_with(stripped_hostnqn)
mock_chmod.assert_called_once_with('/etc/nvme/hostnqn', 0o644)
self.assertEqual(stripped_hostnqn, res)
@mock.patch('os.chmod')
@mock.patch.object(builtins, 'open', new_callable=mock.mock_open)
@mock.patch('os.makedirs')
@mock.patch.object(rootwrap, 'custom_execute')
def test_create_hostnqn_generate(self, mock_exec, mock_mkdirs, mock_open,
mock_chmod):
hostnqn = mock.Mock()
mock_exec.side_effect = [
putils.ProcessExecutionError(exit_code=errno.ENOENT),
(hostnqn, mock.sentinel.err)
]
res = privsep_nvme.create_hostnqn()
mock_mkdirs.assert_called_once_with('/etc/nvme',
mode=0o755,
exist_ok=True)
self.assertEqual(2, mock_exec.call_count)
mock_exec.assert_has_calls([mock.call('nvme', 'show-hostnqn'),
mock.call('nvme', 'gen-hostnqn')])
mock_open.assert_called_once_with('/etc/nvme/hostnqn', 'w')
stripped_hostnqn = hostnqn.strip.return_value
mock_open().write.assert_called_once_with(stripped_hostnqn)
mock_chmod.assert_called_once_with('/etc/nvme/hostnqn', 0o644)
self.assertEqual(stripped_hostnqn, res)
@ddt.data(OSError(errno.ENOENT), # nvme not present in system
putils.ProcessExecutionError(exit_code=123)) # nvme error
@mock.patch('os.makedirs')
@mock.patch.object(rootwrap, 'custom_execute')
def test_create_hostnqn_nvme_not_present(self, exception,
mock_exec, mock_mkdirs):
mock_exec.side_effect = exception
res = privsep_nvme.create_hostnqn()
mock_mkdirs.assert_called_once_with('/etc/nvme',
mode=0o755,
exist_ok=True)
mock_exec.assert_called_once_with('nvme', 'show-hostnqn')
self.assertEqual('', res)

7
releasenotes/notes/nvme-hostnqn-c2611dc56729183b.yaml

@ -0,0 +1,7 @@
---
fixes:
- |
NVMe-oF connector `bug #1928944
<https://bugs.launchpad.net/os-brick/+bug/1928944>`_: Fixed not returning
the right nqn value on ``get_connector_properties`` when
``/etc/nvme/hostnqn`` doesn't exist.
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