Volume discovery and local storage management lib
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os-brick/os_brick/initiator/linuxscsi.py

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# (c) Copyright 2013 Hewlett-Packard Development Company, L.P.
#
# 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.
"""Generic linux scsi subsystem and Multipath utilities.
Note, this is not iSCSI.
"""
import os
import re
import six
from oslo_concurrency import processutils as putils
from oslo_log import log as logging
from os_brick import exception
from os_brick import executor
from os_brick.i18n import _LE, _LI, _LW
from os_brick.privileged import rootwrap as priv_rootwrap
from os_brick import utils
LOG = logging.getLogger(__name__)
MULTIPATH_ERROR_REGEX = re.compile("\w{3} \d+ \d\d:\d\d:\d\d \|.*$")
MULTIPATH_WWID_REGEX = re.compile("\((?P<wwid>.+)\)")
MULTIPATH_DEVICE_ACTIONS = ['unchanged:', 'reject:', 'reload:',
'switchpg:', 'rename:', 'create:',
'resize:']
class LinuxSCSI(executor.Executor):
def echo_scsi_command(self, path, content):
"""Used to echo strings to scsi subsystem."""
args = ["-a", path]
kwargs = dict(process_input=content,
run_as_root=True,
root_helper=self._root_helper)
self._execute('tee', *args, **kwargs)
def get_name_from_path(self, path):
"""Translates /dev/disk/by-path/ entry to /dev/sdX."""
name = os.path.realpath(path)
if name.startswith("/dev/"):
return name
else:
return None
def remove_scsi_device(self, device):
"""Removes a scsi device based upon /dev/sdX name."""
path = "/sys/block/%s/device/delete" % device.replace("/dev/", "")
if os.path.exists(path):
# flush any outstanding IO first
self.flush_device_io(device)
LOG.debug("Remove SCSI device %(device)s with %(path)s",
{'device': device, 'path': path})
self.echo_scsi_command(path, "1")
@utils.retry(exceptions=exception.VolumePathNotRemoved, retries=3,
backoff_rate=2)
def wait_for_volume_removal(self, volume_path):
"""This is used to ensure that volumes are gone."""
LOG.debug("Checking to see if SCSI volume %s has been removed.",
volume_path)
if os.path.exists(volume_path):
LOG.debug("%(path)s still exists.", {'path': volume_path})
raise exception.VolumePathNotRemoved(
volume_path=volume_path)
else:
LOG.debug("SCSI volume %s has been removed.", volume_path)
def get_device_info(self, device):
(out, _err) = self._execute('sg_scan', device, run_as_root=True,
root_helper=self._root_helper)
dev_info = {'device': device, 'host': None,
'channel': None, 'id': None, 'lun': None}
if out:
line = out.strip()
line = line.replace(device + ": ", "")
info = line.split(" ")
for item in info:
if '=' in item:
pair = item.split('=')
dev_info[pair[0]] = pair[1]
elif 'scsi' in item:
dev_info['host'] = item.replace('scsi', '')
return dev_info
def get_scsi_wwn(self, path):
"""Read the WWN from page 0x83 value for a SCSI device."""
(out, _err) = self._execute('/lib/udev/scsi_id', '--page', '0x83',
'--whitelisted', path,
run_as_root=True,
root_helper=self._root_helper)
return out.strip()
@staticmethod
def is_multipath_running(enforce_multipath, root_helper, execute=None):
try:
if execute is None:
execute = priv_rootwrap.execute
execute('multipathd', 'show', 'status',
run_as_root=True, root_helper=root_helper)
except putils.ProcessExecutionError as err:
LOG.error(_LE('multipathd is not running: exit code %(err)s'),
{'err': err.exit_code})
if enforce_multipath:
raise
return False
return True
def remove_multipath_device(self, device):
"""This removes LUNs associated with a multipath device
and the multipath device itself.
"""
LOG.debug("remove multipath device %s", device)
mpath_dev = self.find_multipath_device(device)
if mpath_dev:
self.flush_multipath_device(mpath_dev['name'])
devices = mpath_dev['devices']
LOG.debug("multipath LUNs to remove %s", devices)
for device in devices:
self.remove_scsi_device(device['device'])
def flush_device_io(self, device):
"""This is used to flush any remaining IO in the buffers."""
try:
LOG.debug("Flushing IO for device %s", device)
self._execute('blockdev', '--flushbufs', device, run_as_root=True,
root_helper=self._root_helper)
except putils.ProcessExecutionError as exc:
LOG.warning(_LW("Failed to flush IO buffers prior to removing "
"device: %(code)s"), {'code': exc.exit_code})
def flush_multipath_device(self, device):
try:
LOG.debug("Flush multipath device %s", device)
self._execute('multipath', '-f', device, run_as_root=True,
root_helper=self._root_helper)
except putils.ProcessExecutionError as exc:
LOG.warning(_LW("multipath call failed exit %(code)s"),
{'code': exc.exit_code})
def flush_multipath_devices(self):
try:
self._execute('multipath', '-F', run_as_root=True,
root_helper=self._root_helper)
except putils.ProcessExecutionError as exc:
LOG.warning(_LW("multipath call failed exit %(code)s"),
{'code': exc.exit_code})
@utils.retry(exceptions=exception.VolumeDeviceNotFound)
def wait_for_path(self, volume_path):
"""Wait for a path to show up."""
LOG.debug("Checking to see if %s exists yet.",
volume_path)
if not os.path.exists(volume_path):
LOG.debug("%(path)s doesn't exists yet.", {'path': volume_path})
raise exception.VolumeDeviceNotFound(
device=volume_path)
else:
LOG.debug("%s has shown up.", volume_path)
@utils.retry(exceptions=exception.BlockDeviceReadOnly, retries=5)
def wait_for_rw(self, wwn, device_path):
"""Wait for block device to be Read-Write."""
LOG.debug("Checking to see if %s is read-only.",
device_path)
out, info = self._execute('lsblk', '-o', 'NAME,RO', '-l', '-n')
LOG.debug("lsblk output: %s", out)
blkdevs = out.splitlines()
for blkdev in blkdevs:
# Entries might look like:
#
# "3624a93709a738ed78583fd120013902b (dm-1) 1"
#
# or
#
# "sdd 0"
#
# We are looking for the first and last part of them. For FC
# multipath devices the name is in the format of '<WWN> (dm-<ID>)'
blkdev_parts = blkdev.split(' ')
ro = blkdev_parts[-1]
name = blkdev_parts[0]
# We must validate that all pieces of the dm-# device are rw,
# if some are still ro it can cause problems.
if wwn in name and int(ro) == 1:
LOG.debug("Block device %s is read-only", device_path)
self._execute('multipath', '-r', check_exit_code=[0, 1, 21],
run_as_root=True, root_helper=self._root_helper)
raise exception.BlockDeviceReadOnly(
device=device_path)
else:
LOG.debug("Block device %s is not read-only.", device_path)
def find_multipath_device_path(self, wwn):
"""Look for the multipath device file for a volume WWN.
Multipath devices can show up in several places on
a linux system.
1) When multipath friendly names are ON:
a device file will show up in
/dev/disk/by-id/dm-uuid-mpath-<WWN>
/dev/disk/by-id/dm-name-mpath<N>
/dev/disk/by-id/scsi-mpath<N>
/dev/mapper/mpath<N>
2) When multipath friendly names are OFF:
/dev/disk/by-id/dm-uuid-mpath-<WWN>
/dev/disk/by-id/scsi-<WWN>
/dev/mapper/<WWN>
"""
LOG.info(_LI("Find Multipath device file for volume WWN %(wwn)s"),
{'wwn': wwn})
# First look for the common path
wwn_dict = {'wwn': wwn}
path = "/dev/disk/by-id/dm-uuid-mpath-%(wwn)s" % wwn_dict
try:
self.wait_for_path(path)
return path
except exception.VolumeDeviceNotFound:
pass
# for some reason the common path wasn't found
# lets try the dev mapper path
path = "/dev/mapper/%(wwn)s" % wwn_dict
try:
self.wait_for_path(path)
return path
except exception.VolumeDeviceNotFound:
pass
# couldn't find a path
LOG.warning(_LW("couldn't find a valid multipath device path for "
"%(wwn)s"), wwn_dict)
return None
def find_multipath_device(self, device):
"""Discover multipath devices for a mpath device.
This uses the slow multipath -l command to find a
multipath device description, then screen scrapes
the output to discover the multipath device name
and it's devices.
"""
mdev = None
devices = []
out = None
try:
(out, _err) = self._execute('multipath', '-l', device,
run_as_root=True,
root_helper=self._root_helper)
except putils.ProcessExecutionError as exc:
LOG.warning(_LW("multipath call failed exit %(code)s"),
{'code': exc.exit_code})
raise exception.CommandExecutionFailed(
cmd='multipath -l %s' % device)
if out:
lines = out.strip()
lines = lines.split("\n")
lines = [line for line in lines
if not re.match(MULTIPATH_ERROR_REGEX, line)]
if lines:
mdev_name = lines[0].split(" ")[0]
if mdev_name in MULTIPATH_DEVICE_ACTIONS:
mdev_name = lines[0].split(" ")[1]
mdev = '/dev/mapper/%s' % mdev_name
# Confirm that the device is present.
try:
os.stat(mdev)
except OSError:
LOG.warning(_LW("Couldn't find multipath device %s"),
mdev)
return None
wwid_search = MULTIPATH_WWID_REGEX.search(lines[0])
if wwid_search is not None:
mdev_id = wwid_search.group('wwid')
else:
mdev_id = mdev_name
LOG.debug("Found multipath device = %(mdev)s",
{'mdev': mdev})
device_lines = lines[3:]
for dev_line in device_lines:
if dev_line.find("policy") != -1:
continue
dev_line = dev_line.lstrip(' |-`')
dev_info = dev_line.split()
address = dev_info[0].split(":")
dev = {'device': '/dev/%s' % dev_info[1],
'host': address[0], 'channel': address[1],
'id': address[2], 'lun': address[3]
}
devices.append(dev)
if mdev is not None:
info = {"device": mdev,
"id": mdev_id,
"name": mdev_name,
"devices": devices}
return info
return None
def get_device_size(self, device):
"""Get the size in bytes of a volume."""
(out, _err) = self._execute('blockdev', '--getsize64',
device, run_as_root=True,
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(_LI("mpath(%(device)s) current size %(size)s"),
{'device': mpath_device, 'size': size})
result = self.multipath_resize_map(scsi_wwn)
if 'fail' in result:
msg = (_LI("Multipathd failed to update the size mapping of "
"multipath device %(scsi_wwn)s volume %(volume)s") %
{'scsi_wwn': scsi_wwn, 'volume': volume_paths})
LOG.error(msg)
return None
new_size = self.get_device_size(mpath_device)
LOG.info(_LI("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):
if lun_id < 256:
return lun_id
else:
return ("0x%04x%04x00000000" %
(lun_id & 0xffff, lun_id >> 16 & 0xffff))