176 lines
7.4 KiB
Python
176 lines
7.4 KiB
Python
# Copyright 2015, 2018 IBM Corp.
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#
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# All Rights Reserved.
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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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"""Utilities related to the PowerVM management partition.
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The management partition is a special LPAR that runs the PowerVM REST API
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service. It itself appears through the REST API as a LogicalPartition of type
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aixlinux, but with the is_mgmt_partition property set to True.
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The PowerVM Nova Compute service runs on the management partition.
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"""
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import glob
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import os
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from os import path
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from oslo_concurrency import lockutils
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from oslo_log import log as logging
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from pypowervm.tasks import partition as pvm_par
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import retrying
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from nova import exception
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import nova.privsep.path
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LOG = logging.getLogger(__name__)
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_MP_UUID = None
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@lockutils.synchronized("mgmt_lpar_uuid")
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def mgmt_uuid(adapter):
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"""Returns the management partitions UUID."""
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global _MP_UUID
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if not _MP_UUID:
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_MP_UUID = pvm_par.get_this_partition(adapter).uuid
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return _MP_UUID
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def discover_vscsi_disk(mapping, scan_timeout=300):
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"""Bring a mapped device into the management partition and find its name.
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Based on a VSCSIMapping, scan the appropriate virtual SCSI host bus,
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causing the operating system to discover the mapped device. Find and
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return the path of the newly-discovered device based on its UDID in the
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mapping.
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Note: scanning the bus will cause the operating system to discover *all*
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devices on that bus. However, this method will only return the path for
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the specific device from the input mapping, based on its UDID.
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:param mapping: The pypowervm.wrappers.virtual_io_server.VSCSIMapping
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representing the mapping of the desired disk to the
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management partition.
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:param scan_timeout: The maximum number of seconds after scanning to wait
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for the specified device to appear.
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:return: The udev-generated ("/dev/sdX") name of the discovered disk.
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:raise NoDiskDiscoveryException: If the disk did not appear after the
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specified timeout.
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:raise UniqueDiskDiscoveryException: If more than one disk appears with the
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expected UDID.
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"""
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# Calculate the Linux slot number from the client adapter slot number.
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lslot = 0x30000000 | mapping.client_adapter.lpar_slot_num
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# We'll match the device ID based on the UDID, which is actually the last
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# 32 chars of the field we get from PowerVM.
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udid = mapping.backing_storage.udid[-32:]
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LOG.debug("Trying to discover VSCSI disk with UDID %(udid)s on slot "
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"%(slot)x.", {'udid': udid, 'slot': lslot})
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# Find the special file to scan the bus, and scan it.
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# This glob should yield exactly one result, but use the loop just in case.
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for scanpath in glob.glob(
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'/sys/bus/vio/devices/%x/host*/scsi_host/host*/scan' % lslot):
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# Writing '- - -' to this sysfs file triggers bus rescan
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nova.privsep.path.writefile(scanpath, 'a', '- - -')
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# Now see if our device showed up. If so, we can reliably match it based
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# on its Linux ID, which ends with the disk's UDID.
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dpathpat = '/dev/disk/by-id/*%s' % udid
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# The bus scan is asynchronous. Need to poll, waiting for the device to
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# spring into existence. Stop when glob finds at least one device, or
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# after the specified timeout. Sleep 1/4 second between polls.
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@retrying.retry(retry_on_result=lambda result: not result, wait_fixed=250,
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stop_max_delay=scan_timeout * 1000)
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def _poll_for_dev(globpat):
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return glob.glob(globpat)
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try:
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disks = _poll_for_dev(dpathpat)
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except retrying.RetryError as re:
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raise exception.NoDiskDiscoveryException(
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bus=lslot, udid=udid, polls=re.last_attempt.attempt_number,
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timeout=scan_timeout)
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# If we get here, _poll_for_dev returned a nonempty list. If not exactly
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# one entry, this is an error.
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if len(disks) != 1:
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raise exception.UniqueDiskDiscoveryException(path_pattern=dpathpat,
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count=len(disks))
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# The by-id path is a symlink. Resolve to the /dev/sdX path
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dpath = path.realpath(disks[0])
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LOG.debug("Discovered VSCSI disk with UDID %(udid)s on slot %(slot)x at "
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"path %(devname)s.",
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{'udid': udid, 'slot': lslot, 'devname': dpath})
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return dpath
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def remove_block_dev(devpath, scan_timeout=10):
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"""Remove a block device from the management partition.
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This method causes the operating system of the management partition to
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delete the device special files associated with the specified block device.
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:param devpath: Any path to the block special file associated with the
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device to be removed.
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:param scan_timeout: The maximum number of seconds after scanning to wait
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for the specified device to disappear.
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:raise InvalidDevicePath: If the specified device or its 'delete' special
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file cannot be found.
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:raise DeviceDeletionException: If the deletion was attempted, but the
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device special file is still present
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afterward.
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"""
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# Resolve symlinks, if any, to get to the /dev/sdX path
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devpath = path.realpath(devpath)
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try:
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os.stat(devpath)
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except OSError:
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raise exception.InvalidDevicePath(path=devpath)
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devname = devpath.rsplit('/', 1)[-1]
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delpath = '/sys/block/%s/device/delete' % devname
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try:
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os.stat(delpath)
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except OSError:
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raise exception.InvalidDevicePath(path=delpath)
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LOG.debug("Deleting block device %(devpath)s from the management "
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"partition via special file %(delpath)s.",
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{'devpath': devpath, 'delpath': delpath})
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# Writing '1' to this sysfs file deletes the block device and rescans.
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nova.privsep.path.writefile(delpath, 'a', '1')
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# The bus scan is asynchronous. Need to poll, waiting for the device to
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# disappear. Stop when stat raises OSError (dev file not found) - which is
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# success - or after the specified timeout (which is failure). Sleep 1/4
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# second between polls.
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@retrying.retry(retry_on_result=lambda result: result, wait_fixed=250,
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stop_max_delay=scan_timeout * 1000)
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def _poll_for_del(statpath):
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try:
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os.stat(statpath)
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return True
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except OSError:
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# Device special file is absent, as expected
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return False
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try:
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_poll_for_del(devpath)
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except retrying.RetryError as re:
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# stat just kept returning (dev file continued to exist).
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raise exception.DeviceDeletionException(
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devpath=devpath, polls=re.last_attempt.attempt_number,
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timeout=scan_timeout)
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# Else stat raised - the device disappeared - all done.
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