56c8665d3d
This patch refactors iSCSI connect code changing the approach to one that relies primarily on sysfs, instead of CLI tools, to retrieve all the required information: devices from the connection, multipath system device name, multipath name, the WWN for the block devices... By doing so, not only do we fix a good number of bugs, but we also improve the reliability and speed of the mechanism. A good example of improvements and benefits achieved by this patch are: - Clean all leftovers on exceptions on a connection. - Parallelize logins on multipath to increase speed on flaky network connections. - As long as there is at least one good path when working with multipath we will return a multipath device instead of a single path device, which helps with temporary flaky connections. - Don't use the rescan retry parameter as log in retry on multipath connections so both single and multipath cases are consistent. - We no longer rely on just one device to get the wwn and look for the multipath. This would be problematic with flaky connections. - No more querying iSCSI devices for their WWN (page 0x83) removing delays and issue on flaky connections. - It's no longer a problem for the mechanism the fact that a device exists but is not accessible. - We use links in `/dev/disk/by-id` to get the WWID on connect, so we make sure there are no leftovers on disconnect, but we no longer use symlinks from `/dev/disk/by-path`, `/dev/disk/by-id`, or `/dev/mapper` to find devices. - We no longer need to rely on the WWN to determine the multipath, we have the session and the LUN, so we trace the devices and from those we get if they belong to a multipath. - Stop polluting the logs with unnecessary exceptions from checking if the node or session exist. - Action retries will now only log the final exception instead of logging all the exceptions. - Warn when a multipath could not be formed and a single device is being used, as performance will be degraded. - We no longer do global rescans on single connections that could be bringing in unrelated and unwanted devices (`iscsiadm -T iqn -p portal --rescan`). - Fix scan mechanism that would not request all scans when the same iqn was shareed between portals and could send a scan request to the wrong IP if they shared the same iqn. - When doing single pathed connections we could end with a multipath because we didn't clean up unfruitful connections. It's worth mentioning that this patch does not touch the extend operation. Change-Id: Ia1c47bfaa7bc3544a5feba6a8a30faf2f132b8d7
618 lines
25 KiB
Python
618 lines
25 KiB
Python
# (c) Copyright 2013 Hewlett-Packard Development Company, L.P.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Generic linux scsi subsystem and Multipath utilities.
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Note, this is not iSCSI.
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"""
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import glob
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import os
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import re
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import six
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from oslo_concurrency import processutils as putils
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from oslo_log import log as logging
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from os_brick import exception
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from os_brick import executor
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from os_brick.privileged import rootwrap as priv_rootwrap
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from os_brick import utils
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LOG = logging.getLogger(__name__)
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MULTIPATH_ERROR_REGEX = re.compile("\w{3} \d+ \d\d:\d\d:\d\d \|.*$")
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MULTIPATH_WWID_REGEX = re.compile("\((?P<wwid>.+)\)")
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MULTIPATH_DEVICE_ACTIONS = ['unchanged:', 'reject:', 'reload:',
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'switchpg:', 'rename:', 'create:',
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'resize:']
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class LinuxSCSI(executor.Executor):
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# As found in drivers/scsi/scsi_lib.c
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WWN_TYPES = {'t10.': '1', 'eui.': '2', 'naa.': '3'}
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def echo_scsi_command(self, path, content):
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"""Used to echo strings to scsi subsystem."""
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args = ["-a", path]
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kwargs = dict(process_input=content,
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run_as_root=True,
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root_helper=self._root_helper)
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self._execute('tee', *args, **kwargs)
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def get_name_from_path(self, path):
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"""Translates /dev/disk/by-path/ entry to /dev/sdX."""
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name = os.path.realpath(path)
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if name.startswith("/dev/"):
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return name
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else:
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return None
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def remove_scsi_device(self, device, force=False, exc=None):
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"""Removes a scsi device based upon /dev/sdX name."""
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path = "/sys/block/%s/device/delete" % device.replace("/dev/", "")
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if os.path.exists(path):
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exc = exception.ExceptionChainer() if exc is None else exc
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# flush any outstanding IO first
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with exc.context(force, 'Flushing %s failed', device):
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self.flush_device_io(device)
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LOG.debug("Remove SCSI device %(device)s with %(path)s",
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{'device': device, 'path': path})
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with exc.context(force, 'Removing %s failed', device):
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self.echo_scsi_command(path, "1")
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@utils.retry(exceptions=exception.VolumePathNotRemoved)
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def wait_for_volumes_removal(self, volumes_names):
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"""Wait for device paths to be removed from the system."""
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str_names = ', '.join(volumes_names)
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LOG.debug('Checking to see if SCSI volumes %s have been removed.',
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str_names)
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exist = [volume_name for volume_name in volumes_names
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if os.path.exists('/dev/' + volume_name)]
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if exist:
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LOG.debug('%s still exist.', ', '.join(exist))
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raise exception.VolumePathNotRemoved(volume_path=exist)
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LOG.debug("SCSI volumes %s have been removed.", str_names)
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def get_device_info(self, device):
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(out, _err) = self._execute('sg_scan', device, run_as_root=True,
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root_helper=self._root_helper)
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dev_info = {'device': device, 'host': None,
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'channel': None, 'id': None, 'lun': None}
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if out:
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line = out.strip()
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line = line.replace(device + ": ", "")
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info = line.split(" ")
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for item in info:
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if '=' in item:
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pair = item.split('=')
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dev_info[pair[0]] = pair[1]
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elif 'scsi' in item:
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dev_info['host'] = item.replace('scsi', '')
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return dev_info
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def get_sysfs_wwn(self, device_names):
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"""Return the wwid from sysfs in any of devices in udev format."""
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wwid = self.get_sysfs_wwid(device_names)
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glob_str = '/dev/disk/by-id/scsi-'
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wwn_paths = glob.glob(glob_str + '*')
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# If we don't have multiple designators on page 0x83
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if wwid and glob_str + wwid in wwn_paths:
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return wwid
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# If we have multiple designators follow the symlinks
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for wwn_path in wwn_paths:
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try:
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if os.path.islink(wwn_path) and os.stat(wwn_path):
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path = os.path.realpath(wwn_path)
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if path.startswith('/dev/') and path[5:] in device_names:
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return wwn_path[len(glob_str):]
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except OSError:
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continue
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return ''
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def get_sysfs_wwid(self, device_names):
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"""Return the wwid from sysfs in any of devices in udev format."""
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for device_name in device_names:
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try:
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with open('/sys/block/%s/device/wwid' % device_name) as f:
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wwid = f.read().strip()
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except IOError:
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continue
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# The sysfs wwid has the wwn type in string format as a prefix,
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# but udev uses its numerical representation as returned by
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# scsi_id's page 0x83, so we need to map it
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udev_wwid = self.WWN_TYPES.get(wwid[:4], '8') + wwid[4:]
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return udev_wwid
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return ''
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def get_scsi_wwn(self, path):
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"""Read the WWN from page 0x83 value for a SCSI device."""
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(out, _err) = self._execute('/lib/udev/scsi_id', '--page', '0x83',
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'--whitelisted', path,
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run_as_root=True,
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root_helper=self._root_helper)
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return out.strip()
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@staticmethod
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def is_multipath_running(enforce_multipath, root_helper, execute=None):
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try:
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if execute is None:
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execute = priv_rootwrap.execute
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execute('multipathd', 'show', 'status',
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run_as_root=True, root_helper=root_helper)
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except putils.ProcessExecutionError as err:
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LOG.error('multipathd is not running: exit code %(err)s',
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{'err': err.exit_code})
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if enforce_multipath:
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raise
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return False
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return True
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def get_dm_name(self, dm):
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"""Get the Device map name given the device name of the dm on sysfs.
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:param dm: Device map name as seen in sysfs. ie: 'dm-0'
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:returns: String with the name, or empty string if not available.
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ie: '36e843b658476b7ed5bc1d4d10d9b1fde'
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"""
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try:
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with open('/sys/block/' + dm + '/dm/name') as f:
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return f.read().strip()
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except IOError:
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return ''
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def find_sysfs_multipath_dm(self, device_names):
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"""Find the dm device name given a list of device names
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:param device_names: Iterable with device names, not paths. ie: ['sda']
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:returns: String with the dm name or None if not found. ie: 'dm-0'
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"""
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glob_str = '/sys/block/%s/holders/dm-*'
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for dev_name in device_names:
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dms = glob.glob(glob_str % dev_name)
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if dms:
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__, device_name, __, dm = dms[0].rsplit('/', 3)
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return dm
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return None
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def remove_connection(self, devices_names, is_multipath, force=False,
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exc=None):
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"""Remove LUNs and multipath associated with devices names.
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:param devices_names: Iterable with real device names ('sda', 'sdb')
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:param is_multipath: Whether this is a multipath connection or not
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:param force: Whether to forcefully disconnect even if flush fails.
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:param exc: ExceptionChainer where to add exceptions if forcing
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:returns: Multipath device map name if found and not flushed
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"""
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if not devices_names:
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return
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multipath_name = None
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exc = exception.ExceptionChainer() if exc is None else exc
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LOG.debug('Removing %(type)s devices %(devices)s',
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{'type': 'multipathed' if is_multipath else 'single pathed',
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'devices': ', '.join(devices_names)})
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if is_multipath:
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multipath_dm = self.find_sysfs_multipath_dm(devices_names)
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multipath_name = multipath_dm and self.get_dm_name(multipath_dm)
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if multipath_name:
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with exc.context(force, 'Flushing %s failed', multipath_name):
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self.flush_multipath_device(multipath_name)
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multipath_name = None
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for device_name in devices_names:
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self.remove_scsi_device('/dev/' + device_name, force, exc)
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# Wait until the symlinks are removed
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with exc.context(force, 'Some devices remain from %s', devices_names):
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try:
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self.wait_for_volumes_removal(devices_names)
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finally:
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# Since we use /dev/disk/by-id/scsi- links to get the wwn we
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# must ensure they are always removed.
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self._remove_scsi_symlinks(devices_names)
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return multipath_name
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def _remove_scsi_symlinks(self, devices_names):
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devices = ['/dev/' + dev for dev in devices_names]
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links = glob.glob('/dev/disk/by-id/scsi-*')
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unlink = [link for link in links
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if os.path.realpath(link) in devices]
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if unlink:
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priv_rootwrap.unlink_root(no_errors=True, *unlink)
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def flush_device_io(self, device):
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"""This is used to flush any remaining IO in the buffers."""
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if os.path.exists(device):
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try:
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# NOTE(geguileo): With 30% connection error rates flush can get
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# stuck, set timeout to prevent it from hanging here forever.
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# Retry twice after 20 and 40 seconds.
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LOG.debug("Flushing IO for device %s", device)
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self._execute('blockdev', '--flushbufs', device,
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run_as_root=True, attempts=3, timeout=300,
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interval=10, root_helper=self._root_helper)
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except putils.ProcessExecutionError as exc:
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LOG.warning("Failed to flush IO buffers prior to removing "
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"device: %(code)s", {'code': exc.exit_code})
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raise
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def flush_multipath_device(self, device_map_name):
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LOG.debug("Flush multipath device %s", device_map_name)
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# NOTE(geguileo): With 30% connection error rates flush can get stuck,
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# set timeout to prevent it from hanging here forever. Retry twice
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# after 20 and 40 seconds.
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self._execute('multipath', '-f', device_map_name, run_as_root=True,
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attempts=3, timeout=300, interval=10,
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root_helper=self._root_helper)
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@utils.retry(exceptions=exception.VolumeDeviceNotFound)
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def wait_for_path(self, volume_path):
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"""Wait for a path to show up."""
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LOG.debug("Checking to see if %s exists yet.",
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volume_path)
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if not os.path.exists(volume_path):
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LOG.debug("%(path)s doesn't exists yet.", {'path': volume_path})
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raise exception.VolumeDeviceNotFound(
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device=volume_path)
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else:
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LOG.debug("%s has shown up.", volume_path)
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@utils.retry(exceptions=exception.BlockDeviceReadOnly, retries=5)
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def wait_for_rw(self, wwn, device_path):
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"""Wait for block device to be Read-Write."""
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LOG.debug("Checking to see if %s is read-only.",
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device_path)
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out, info = self._execute('lsblk', '-o', 'NAME,RO', '-l', '-n')
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LOG.debug("lsblk output: %s", out)
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blkdevs = out.splitlines()
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for blkdev in blkdevs:
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# Entries might look like:
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#
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# "3624a93709a738ed78583fd120013902b (dm-1) 1"
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#
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# or
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#
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# "sdd 0"
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#
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# We are looking for the first and last part of them. For FC
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# multipath devices the name is in the format of '<WWN> (dm-<ID>)'
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blkdev_parts = blkdev.split(' ')
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ro = blkdev_parts[-1]
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name = blkdev_parts[0]
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# We must validate that all pieces of the dm-# device are rw,
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# if some are still ro it can cause problems.
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if wwn in name and int(ro) == 1:
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LOG.debug("Block device %s is read-only", device_path)
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self._execute('multipath', '-r', check_exit_code=[0, 1, 21],
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run_as_root=True, root_helper=self._root_helper)
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raise exception.BlockDeviceReadOnly(
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device=device_path)
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else:
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LOG.debug("Block device %s is not read-only.", device_path)
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def find_multipath_device_path(self, wwn):
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"""Look for the multipath device file for a volume WWN.
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Multipath devices can show up in several places on
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a linux system.
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1) When multipath friendly names are ON:
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a device file will show up in
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/dev/disk/by-id/dm-uuid-mpath-<WWN>
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/dev/disk/by-id/dm-name-mpath<N>
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/dev/disk/by-id/scsi-mpath<N>
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/dev/mapper/mpath<N>
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2) When multipath friendly names are OFF:
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/dev/disk/by-id/dm-uuid-mpath-<WWN>
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/dev/disk/by-id/scsi-<WWN>
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/dev/mapper/<WWN>
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"""
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LOG.info("Find Multipath device file for volume WWN %(wwn)s",
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{'wwn': wwn})
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# First look for the common path
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wwn_dict = {'wwn': wwn}
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path = "/dev/disk/by-id/dm-uuid-mpath-%(wwn)s" % wwn_dict
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try:
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self.wait_for_path(path)
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return path
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except exception.VolumeDeviceNotFound:
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pass
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# for some reason the common path wasn't found
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# lets try the dev mapper path
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path = "/dev/mapper/%(wwn)s" % wwn_dict
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try:
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self.wait_for_path(path)
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return path
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except exception.VolumeDeviceNotFound:
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pass
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# couldn't find a path
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LOG.warning("couldn't find a valid multipath device path for "
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"%(wwn)s", wwn_dict)
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return None
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def find_multipath_device(self, device):
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"""Discover multipath devices for a mpath device.
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This uses the slow multipath -l command to find a
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multipath device description, then screen scrapes
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the output to discover the multipath device name
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and it's devices.
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"""
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mdev = None
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devices = []
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out = None
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try:
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(out, _err) = self._execute('multipath', '-l', device,
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run_as_root=True,
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root_helper=self._root_helper)
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except putils.ProcessExecutionError as exc:
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LOG.warning("multipath call failed exit %(code)s",
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{'code': exc.exit_code})
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raise exception.CommandExecutionFailed(
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cmd='multipath -l %s' % device)
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if out:
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lines = out.strip()
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lines = lines.split("\n")
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lines = [line for line in lines
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if not re.match(MULTIPATH_ERROR_REGEX, line)]
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if lines:
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mdev_name = lines[0].split(" ")[0]
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if mdev_name in MULTIPATH_DEVICE_ACTIONS:
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mdev_name = lines[0].split(" ")[1]
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mdev = '/dev/mapper/%s' % mdev_name
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# Confirm that the device is present.
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try:
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os.stat(mdev)
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except OSError:
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LOG.warning("Couldn't find multipath device %s",
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mdev)
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return None
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wwid_search = MULTIPATH_WWID_REGEX.search(lines[0])
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if wwid_search is not None:
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mdev_id = wwid_search.group('wwid')
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else:
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mdev_id = mdev_name
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LOG.debug("Found multipath device = %(mdev)s",
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{'mdev': mdev})
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device_lines = lines[3:]
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for dev_line in device_lines:
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if dev_line.find("policy") != -1:
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continue
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dev_line = dev_line.lstrip(' |-`')
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dev_info = dev_line.split()
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address = dev_info[0].split(":")
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dev = {'device': '/dev/%s' % dev_info[1],
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'host': address[0], 'channel': address[1],
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'id': address[2], 'lun': address[3]
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}
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devices.append(dev)
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if mdev is not None:
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info = {"device": mdev,
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"id": mdev_id,
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"name": mdev_name,
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"devices": devices}
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return info
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return None
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def get_device_size(self, device):
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"""Get the size in bytes of a volume."""
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(out, _err) = self._execute('blockdev', '--getsize64',
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device, run_as_root=True,
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root_helper=self._root_helper)
|
|
var = six.text_type(out.strip())
|
|
if var.isnumeric():
|
|
return int(var)
|
|
else:
|
|
return None
|
|
|
|
def multipath_reconfigure(self):
|
|
"""Issue a multipathd reconfigure.
|
|
|
|
When attachments come and go, the multipathd seems
|
|
to get lost and not see the maps. This causes
|
|
resize map to fail 100%. To overcome this we have
|
|
to issue a reconfigure prior to resize map.
|
|
"""
|
|
(out, _err) = self._execute('multipathd', 'reconfigure',
|
|
run_as_root=True,
|
|
root_helper=self._root_helper)
|
|
return out
|
|
|
|
def multipath_resize_map(self, mpath_id):
|
|
"""Issue a multipath resize map on device.
|
|
|
|
This forces the multipath daemon to update it's
|
|
size information a particular multipath device.
|
|
"""
|
|
(out, _err) = self._execute('multipathd', 'resize', 'map', mpath_id,
|
|
run_as_root=True,
|
|
root_helper=self._root_helper)
|
|
return out
|
|
|
|
def extend_volume(self, volume_paths):
|
|
"""Signal the SCSI subsystem to test for volume resize.
|
|
|
|
This function tries to signal the local system's kernel
|
|
that an already attached volume might have been resized.
|
|
"""
|
|
LOG.debug("extend volume %s", volume_paths)
|
|
|
|
for volume_path in volume_paths:
|
|
device = self.get_device_info(volume_path)
|
|
LOG.debug("Volume device info = %s", device)
|
|
device_id = ("%(host)s:%(channel)s:%(id)s:%(lun)s" %
|
|
{'host': device['host'],
|
|
'channel': device['channel'],
|
|
'id': device['id'],
|
|
'lun': device['lun']})
|
|
|
|
scsi_path = ("/sys/bus/scsi/drivers/sd/%(device_id)s" %
|
|
{'device_id': device_id})
|
|
|
|
size = self.get_device_size(volume_path)
|
|
LOG.debug("Starting size: %s", size)
|
|
|
|
# now issue the device rescan
|
|
rescan_path = "%(scsi_path)s/rescan" % {'scsi_path': scsi_path}
|
|
self.echo_scsi_command(rescan_path, "1")
|
|
new_size = self.get_device_size(volume_path)
|
|
LOG.debug("volume size after scsi device rescan %s", new_size)
|
|
|
|
scsi_wwn = self.get_scsi_wwn(volume_paths[0])
|
|
mpath_device = self.find_multipath_device_path(scsi_wwn)
|
|
if mpath_device:
|
|
# Force a reconfigure so that resize works
|
|
self.multipath_reconfigure()
|
|
|
|
size = self.get_device_size(mpath_device)
|
|
LOG.info("mpath(%(device)s) current size %(size)s",
|
|
{'device': mpath_device, 'size': size})
|
|
result = self.multipath_resize_map(scsi_wwn)
|
|
if 'fail' in result:
|
|
LOG.error("Multipathd failed to update the size mapping of "
|
|
"multipath device %(scsi_wwn)s volume %(volume)s",
|
|
{'scsi_wwn': scsi_wwn, 'volume': volume_paths})
|
|
return None
|
|
|
|
new_size = self.get_device_size(mpath_device)
|
|
LOG.info("mpath(%(device)s) new size %(size)s",
|
|
{'device': mpath_device, 'size': new_size})
|
|
|
|
return new_size
|
|
|
|
def process_lun_id(self, lun_ids):
|
|
if isinstance(lun_ids, list):
|
|
processed = []
|
|
for x in lun_ids:
|
|
x = self._format_lun_id(x)
|
|
processed.append(x)
|
|
else:
|
|
processed = self._format_lun_id(lun_ids)
|
|
return processed
|
|
|
|
def _format_lun_id(self, lun_id):
|
|
# make sure lun_id is an int
|
|
lun_id = int(lun_id)
|
|
if lun_id < 256:
|
|
return lun_id
|
|
else:
|
|
return ("0x%04x%04x00000000" %
|
|
(lun_id & 0xffff, lun_id >> 16 & 0xffff))
|
|
|
|
def get_hctl(self, session, lun):
|
|
"""Given an iSCSI session return the host, channel, target, and lun."""
|
|
glob_str = '/sys/class/iscsi_host/host*/device/session' + session
|
|
paths = glob.glob(glob_str + '/target*')
|
|
if paths:
|
|
__, channel, target = os.path.split(paths[0])[1].split(':')
|
|
# Check if we can get the host
|
|
else:
|
|
target = channel = '-'
|
|
paths = glob.glob(glob_str)
|
|
|
|
if not paths:
|
|
LOG.debug('No hctl found on session %s with lun %s', session, lun)
|
|
return None
|
|
|
|
# Extract the host number from the path
|
|
host = paths[0][26:paths[0].index('/', 26)]
|
|
res = (host, channel, target, lun)
|
|
LOG.debug('HCTL %s found on session %s with lun %s', res, session, lun)
|
|
return res
|
|
|
|
def device_name_by_hctl(self, session, hctl):
|
|
"""Find the device name given a session and the hctl.
|
|
|
|
:param session: A string with the session number
|
|
"param hctl: An iterable with the host, channel, target, and lun as
|
|
passed to scan. ie: ('5', '-', '-', '0')
|
|
"""
|
|
if '-' in hctl:
|
|
hctl = ['*' if x == '-' else x for x in hctl]
|
|
path = ('/sys/class/scsi_host/host%(h)s/device/session%(s)s/target'
|
|
'%(h)s:%(c)s:%(t)s/%(h)s:%(c)s:%(t)s:%(l)s/block/*' %
|
|
{'h': hctl[0], 'c': hctl[1], 't': hctl[2], 'l': hctl[3],
|
|
's': session})
|
|
# Sort devices and return the first so we don't return a partition
|
|
devices = sorted(glob.glob(path))
|
|
device = os.path.split(devices[0])[1] if devices else None
|
|
LOG.debug('Searching for a device in session %s and hctl %s yield: %s',
|
|
session, hctl, device)
|
|
return device
|
|
|
|
def scan_iscsi(self, host, channel='-', target='-', lun='-'):
|
|
"""Send an iSCSI scan request given the host and optionally the ctl."""
|
|
LOG.debug('Scanning host %(host)s c: %(channel)s, '
|
|
't: %(target)s, l: %(lun)s)',
|
|
{'host': host, 'channel': channel,
|
|
'target': target, 'lun': lun})
|
|
self.echo_scsi_command('/sys/class/scsi_host/host%s/scan' % host,
|
|
'%(c)s %(t)s %(l)s' % {'c': channel,
|
|
't': target,
|
|
'l': lun})
|
|
|
|
def multipath_add_wwid(self, wwid):
|
|
"""Add a wwid to the list of know multipath wwids.
|
|
|
|
This has the effect of multipathd being willing to create a dm for a
|
|
multipath even when there's only 1 device.
|
|
"""
|
|
out, err = self._execute('multipath', '-a', wwid,
|
|
run_as_root=True,
|
|
check_exit_code=False,
|
|
root_helper=self._root_helper)
|
|
return out.strip() == "wwid '" + wwid + "' added"
|
|
|
|
def multipath_add_path(self, realpath):
|
|
"""Add a path to multipathd for monitoring.
|
|
|
|
This has the effect of multipathd checking an already checked device
|
|
for multipath.
|
|
|
|
Together with `multipath_add_wwid` we can create a multipath when
|
|
there's only 1 path.
|
|
"""
|
|
stdout, stderr = self._execute('multipathd', 'add', 'path', realpath,
|
|
run_as_root=True, timeout=5,
|
|
check_exit_code=False,
|
|
root_helper=self._root_helper)
|
|
return stdout.strip() == 'ok'
|