de89635ab7
On iSCSI connections, when we are making sure that there no links remain
like /dev/disk/by-id/scsi-* we make several calls to os.path.realpath
which normal behavior is:
- If file path doesn't exist, returns the same file path
- If file path exists, return the real path
But there is a third option, and that is when the file did exist but it
dissapear right when the call to os.readlink in posixpath:_joinrealpath
path, ok = _joinrealpath(path, os.readlink(newpath), seen)
Which ends up raising an exception such as:
OSError: [Errno 2] No such file or directory:
'/dev/disk/by-id/scsi-20024f40058540081'
And because of this exception the detach will fail when it shouldn't.
This patch adds includes the call to os.path.realpath within a
try...except clause to prevent this race condition from unexpectely
making the detach operation fail.
Change-Id: Ieb58826b28c62094c941fce10863c0a75fb4e8aa
Closes-Bug: #1719719
627 lines
25 KiB
Python
627 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 = []
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for link in links:
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try:
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if os.path.realpath(link) in devices:
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unlink.append(link)
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except OSError:
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# A race condition in Python's posixpath:realpath just occurred
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# so we can ignore it because the file was just removed between
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# a check if file exists and a call to os.readlink
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continue
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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)
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var = six.text_type(out.strip())
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if var.isnumeric():
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return int(var)
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else:
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return None
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def multipath_reconfigure(self):
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"""Issue a multipathd reconfigure.
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When attachments come and go, the multipathd seems
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to get lost and not see the maps. This causes
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resize map to fail 100%. To overcome this we have
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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'
|