# Copyright (c) 2014, 2016, Oracle and/or its affiliates. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
ZFS Storage Appliance NFS Cinder Volume Driver
"""
import datetime as dt
import errno
import math
import os

from oslo_config import cfg
from oslo_log import log
from oslo_serialization import base64
from oslo_utils import excutils
from oslo_utils import units
import six

from cinder import exception
from cinder.i18n import _
from cinder.image import image_utils
from cinder import interface
from cinder.objects.volume import Volume
from cinder import utils
from cinder.volume import configuration
from cinder.volume.drivers import nfs
from cinder.volume.drivers.san import san
from cinder.volume.drivers.zfssa import zfssarest
from cinder.volume import utils as vutils


ZFSSA_OPTS = [
    cfg.StrOpt('zfssa_data_ip',
               help='Data path IP address'),
    cfg.StrOpt('zfssa_https_port', default='443',
               help='HTTPS port number'),
    cfg.StrOpt('zfssa_nfs_mount_options', default='',
               help='Options to be passed while mounting share over nfs'),
    cfg.StrOpt('zfssa_nfs_pool', default='',
               help='Storage pool name.'),
    cfg.StrOpt('zfssa_nfs_project', default='NFSProject',
               help='Project name.'),
    cfg.StrOpt('zfssa_nfs_share', default='nfs_share',
               help='Share name.'),
    cfg.StrOpt('zfssa_nfs_share_compression', default='off',
               choices=['off', 'lzjb', 'gzip-2', 'gzip', 'gzip-9'],
               help='Data compression.'),
    cfg.StrOpt('zfssa_nfs_share_logbias', default='latency',
               choices=['latency', 'throughput'],
               help='Synchronous write bias-latency, throughput.'),
    cfg.IntOpt('zfssa_rest_timeout',
               help='REST connection timeout. (seconds)'),
    cfg.BoolOpt('zfssa_enable_local_cache', default=True,
                help='Flag to enable local caching: True, False.'),
    cfg.StrOpt('zfssa_cache_directory', default='os-cinder-cache',
               help='Name of directory inside zfssa_nfs_share where cache '
                    'volumes are stored.'),
    cfg.StrOpt('zfssa_manage_policy', default='loose',
               choices=['loose', 'strict'],
               help='Driver policy for volume manage.')
]

LOG = log.getLogger(__name__)

CONF = cfg.CONF
CONF.register_opts(ZFSSA_OPTS, group=configuration.SHARED_CONF_GROUP)


def factory_zfssa():
    return zfssarest.ZFSSANfsApi()


@interface.volumedriver
class ZFSSANFSDriver(nfs.NfsDriver):
    """ZFSSA Cinder NFS volume driver.

    Version history:

    .. code-block:: none

        1.0.1:
            Backend enabled volume migration.
            Local cache feature.
        1.0.2:
            Volume manage/unmanage support.
    """
    VERSION = '1.0.2'
    volume_backend_name = 'ZFSSA_NFS'
    protocol = driver_prefix = driver_volume_type = 'nfs'

    # ThirdPartySystems wiki page
    CI_WIKI_NAME = "Oracle_ZFSSA_CI"

    def __init__(self, *args, **kwargs):
        super(ZFSSANFSDriver, self).__init__(*args, **kwargs)
        self.configuration.append_config_values(ZFSSA_OPTS)
        self.configuration.append_config_values(san.san_opts)
        self.zfssa = None
        self._stats = None

    def do_setup(self, context):
        self.configuration.max_over_subscription_ratio = (
            vutils.get_max_over_subscription_ratio(
                self.configuration.max_over_subscription_ratio,
                supports_auto=False))

        if not self.configuration.max_over_subscription_ratio > 0:
            msg = _("Config 'max_over_subscription_ratio' invalid. Must be > "
                    "0: %s") % self.configuration.max_over_subscription_ratio
            LOG.error(msg)
            raise exception.NfsException(msg)

        packages = ('mount.nfs', '/usr/sbin/mount')
        for package in packages:
            try:
                self._execute(package, check_exit_code=False, run_as_root=True)
                break
            except OSError as exc:
                if exc.errno != errno.ENOENT:
                    raise
                LOG.error('%s is not installed.', package)
        else:
            msg = utils.build_or_str(packages, '%s needs to be installed.')
            raise exception.NfsException(msg)

        lcfg = self.configuration
        LOG.info('Connecting to host: %s.', lcfg.san_ip)

        host = lcfg.san_ip
        user = lcfg.san_login
        password = lcfg.san_password
        https_port = lcfg.zfssa_https_port

        credentials = ['san_ip', 'san_login', 'san_password', 'zfssa_data_ip']

        for cred in credentials:
            if not getattr(lcfg, cred, None):
                exception_msg = _('%s not set in cinder.conf') % cred
                LOG.error(exception_msg)
                raise exception.CinderException(exception_msg)

        self.zfssa = factory_zfssa()
        self.zfssa.set_host(host, timeout=lcfg.zfssa_rest_timeout)

        auth_str = base64.encode_as_text('%s:%s' % (user, password))
        self.zfssa.login(auth_str)

        self.zfssa.create_project(lcfg.zfssa_nfs_pool, lcfg.zfssa_nfs_project,
                                  compression=lcfg.zfssa_nfs_share_compression,
                                  logbias=lcfg.zfssa_nfs_share_logbias)

        share_args = {
            'sharedav': 'rw',
            'sharenfs': 'rw',
            'root_permissions': '777',
            'compression': lcfg.zfssa_nfs_share_compression,
            'logbias': lcfg.zfssa_nfs_share_logbias
        }

        self.zfssa.create_share(lcfg.zfssa_nfs_pool, lcfg.zfssa_nfs_project,
                                lcfg.zfssa_nfs_share, share_args)

        share_details = self.zfssa.get_share(lcfg.zfssa_nfs_pool,
                                             lcfg.zfssa_nfs_project,
                                             lcfg.zfssa_nfs_share)

        mountpoint = share_details['mountpoint']

        self.mount_path = lcfg.zfssa_data_ip + ':' + mountpoint
        https_path = 'https://' + lcfg.zfssa_data_ip + ':' + https_port + \
            '/shares' + mountpoint

        LOG.debug('NFS mount path: %s', self.mount_path)
        LOG.debug('WebDAV path to the share: %s', https_path)

        self.shares = {}
        mnt_opts = self.configuration.zfssa_nfs_mount_options
        self.shares[self.mount_path] = mnt_opts if len(mnt_opts) > 1 else None

        # Initialize the WebDAV client
        self.zfssa.set_webdav(https_path, auth_str)

        # Edit http service so that WebDAV requests are always authenticated
        args = {'https_port': https_port,
                'require_login': True}

        self.zfssa.modify_service('http', args)
        self.zfssa.enable_service('http')

        if lcfg.zfssa_enable_local_cache:
            LOG.debug('Creating local cache directory %s.',
                      lcfg.zfssa_cache_directory)
            self.zfssa.create_directory(lcfg.zfssa_cache_directory)

    def _ensure_shares_mounted(self):
        try:
            self._ensure_share_mounted(self.mount_path)
        except Exception as exc:
            LOG.error('Exception during mounting %s.', exc)

        self._mounted_shares = [self.mount_path]
        LOG.debug('Available shares %s', self._mounted_shares)

    def check_for_setup_error(self):
        """Check that driver can login.

        Check also for properly configured pool, project and share
        Check that the http and nfs services are enabled
        """
        lcfg = self.configuration

        self.zfssa.verify_pool(lcfg.zfssa_nfs_pool)
        self.zfssa.verify_project(lcfg.zfssa_nfs_pool, lcfg.zfssa_nfs_project)
        self.zfssa.verify_share(lcfg.zfssa_nfs_pool, lcfg.zfssa_nfs_project,
                                lcfg.zfssa_nfs_share)
        self.zfssa.verify_service('http')
        self.zfssa.verify_service('nfs')

    def create_volume(self, volume):
        ret = super(ZFSSANFSDriver, self).create_volume(volume)
        self.zfssa.set_file_props(volume.name, {'cinder_managed': 'True'})
        return ret

    def create_snapshot(self, snapshot):
        """Creates a snapshot of a volume."""
        LOG.info('Creating snapshot: %s', snapshot['name'])
        lcfg = self.configuration
        snap_name = self._create_snapshot_name()
        self.zfssa.create_snapshot(lcfg.zfssa_nfs_pool, lcfg.zfssa_nfs_project,
                                   lcfg.zfssa_nfs_share, snap_name)

        src_file = snap_name + '/' + snapshot['volume_name']

        try:
            self.zfssa.create_snapshot_of_volume_file(src_file=src_file,
                                                      dst_file=
                                                      snapshot['name'])
        except Exception:
            with excutils.save_and_reraise_exception():
                LOG.debug('Error thrown during snapshot: %s creation',
                          snapshot['name'])
        finally:
            self.zfssa.delete_snapshot(lcfg.zfssa_nfs_pool,
                                       lcfg.zfssa_nfs_project,
                                       lcfg.zfssa_nfs_share, snap_name)

    def delete_snapshot(self, snapshot):
        """Deletes a snapshot."""
        LOG.info('Deleting snapshot: %s', snapshot['name'])
        self.zfssa.delete_snapshot_of_volume_file(src_file=snapshot['name'])

    def create_volume_from_snapshot(self, volume, snapshot, method='COPY'):
        LOG.info('Creatng volume from snapshot. volume: %s',
                 volume['name'])
        LOG.info('Source Snapshot: %s', snapshot['name'])

        self._ensure_shares_mounted()
        self.zfssa.create_volume_from_snapshot_file(src_file=snapshot['name'],
                                                    dst_file=volume['name'],
                                                    method=method)

        volume['provider_location'] = self.mount_path

        if volume['size'] != snapshot['volume_size']:
            try:
                self.extend_volume(volume, volume['size'])
            except Exception:
                vol_path = self.local_path(volume)
                with excutils.save_and_reraise_exception():
                    LOG.error('Error in extending volume size: Volume: '
                              '%(volume)s Vol_Size: %(vol_size)d with '
                              'Snapshot: %(snapshot)s Snap_Size: '
                              '%(snap_size)d',
                              {'volume': volume['name'],
                               'vol_size': volume['size'],
                               'snapshot': snapshot['name'],
                               'snap_size': snapshot['volume_size']})
                    self._execute('rm', '-f', vol_path, run_as_root=True)

        volume_origin = {'origin': snapshot['volume_name'],
                         'cinder_managed': 'True'}
        self.zfssa.set_file_props(volume['name'], volume_origin)

        return {'provider_location': volume['provider_location']}

    def create_cloned_volume(self, volume, src_vref):
        """Creates a snapshot and then clones the snapshot into a volume."""
        LOG.info('new cloned volume: %s', volume['name'])
        LOG.info('source volume for cloning: %s', src_vref['name'])

        snapshot = {'volume_name': src_vref['name'],
                    'volume_id': src_vref['id'],
                    'volume_size': src_vref['size'],
                    'name': self._create_snapshot_name()}

        self.create_snapshot(snapshot)
        return self.create_volume_from_snapshot(volume, snapshot,
                                                method='MOVE')

    def delete_volume(self, volume):
        LOG.debug('Deleting volume %s.', volume.name)
        lcfg = self.configuration
        try:
            vol_props = self.zfssa.get_volume(volume.name)
        except exception.VolumeNotFound:
            return
        super(ZFSSANFSDriver, self).delete_volume(volume)

        if vol_props['origin'].startswith(lcfg.zfssa_cache_directory):
            LOG.info('Checking origin %(origin)s of volume %(volume)s.',
                     {'origin': vol_props['origin'],
                      'volume': volume.name})
            self._check_origin(vol_props['origin'])

    @utils.synchronized('zfssanfs', external=True)
    def clone_image(self, context, volume,
                    image_location, image_meta,
                    image_service):
        """Create a volume efficiently from an existing image.

        Verify the image ID being used:

        (1) If there is no existing cache volume, create one and transfer
        image data to it. Take a snapshot.

        (2) If a cache volume already exists, verify if it is either alternated
        or updated. If so try to remove it, raise exception if removal fails.
        Create a new cache volume as in (1).

        Clone a volume from the cache volume and returns it to Cinder.

        A file lock is placed on this method to prevent:
        (a) a race condition when a cache volume has been verified, but then
        gets deleted before it is cloned.

        (b) failure of subsequent clone_image requests if the first request is
        still pending.
        """
        LOG.debug('Cloning image %(image)s to volume %(volume)s',
                  {'image': image_meta['id'], 'volume': volume['name']})
        lcfg = self.configuration
        cachevol_size = 0
        if not lcfg.zfssa_enable_local_cache:
            return None, False

        with image_utils.TemporaryImages.fetch(
                image_service, context, image_meta['id']) as tmp_image:
            info = image_utils.qemu_img_info(tmp_image)
            cachevol_size = int(math.ceil(float(info.virtual_size) / units.Gi))

        if cachevol_size > volume['size']:
            exception_msg = ('Image size %(img_size)dGB is larger '
                             'than volume size %(vol_size)dGB.',
                             {'img_size': cachevol_size,
                              'vol_size': volume['size']})
            LOG.error(exception_msg)
            return None, False

        updated_at = six.text_type(image_meta['updated_at'].isoformat())
        cachevol_props = {
            'id': image_meta['id'],
            'size': cachevol_size,
            'updated_at': updated_at,
            'image_id': image_meta['id'],
        }

        try:
            cachevol_name = self._verify_cache_volume(context,
                                                      image_meta,
                                                      image_service,
                                                      cachevol_props)
            # A cache volume should be ready by now
            # Create a clone from the cache volume
            cache_vol = {
                'name': cachevol_name,
                'size': cachevol_size,
                'id': image_meta['id'],
            }
            clone_vol = self.create_cloned_volume(volume, cache_vol)
            self._update_origin(volume['name'], cachevol_name)
        except exception.VolumeBackendAPIException as exc:
            exception_msg = ('Cannot clone image %(image)s to '
                             'volume %(volume)s. Error: %(error)s.',
                             {'volume': volume['name'],
                              'image': image_meta['id'],
                              'error': exc.msg})
            LOG.error(exception_msg)
            return None, False

        return clone_vol, True

    def _verify_cache_volume(self, context, img_meta,
                             img_service, cachevol_props):
        """Verify if we have a cache volume that we want.

        If we don't, create one.
        If we do, check if it's been updated:
          * If so, delete it and recreate a new volume
          * If not, we are good.

        If it's out of date, delete it and create a new one.

        After the function returns, there should be a cache volume available,
        ready for cloning.
        """
        lcfg = self.configuration
        cache_dir = '%s/' % lcfg.zfssa_cache_directory
        cache_vol_obj = Volume()
        cache_vol_obj.provider_location = self.mount_path + '/' + cache_dir
        cache_vol_obj._name_id = cachevol_props['id']
        cachevol_name = cache_dir + cache_vol_obj.name

        LOG.debug('Verifying cache volume %s:', cachevol_name)

        try:
            cache_vol = self.zfssa.get_volume(cachevol_name)
        except exception.VolumeNotFound:
            # There is no existing cache volume, create one:
            LOG.debug('Cache volume not found. Creating one...')
            return self._create_cache_volume(context,
                                             img_meta,
                                             img_service,
                                             cachevol_props)

        # A cache volume does exist, check if it's updated:
        if ((cache_vol['updated_at'] != cachevol_props['updated_at']) or
                (cache_vol['image_id'] != cachevol_props['image_id'])):
            if cache_vol['numclones'] > 0:
                # The cache volume is updated, but has clones
                exception_msg = (_('Cannot delete '
                                   'cache volume: %(cachevol_name)s. '
                                   'It was updated at %(updated_at)s '
                                   'and currently has %(numclones)d '
                                   'volume instances.'),
                                 {'cachevol_name': cachevol_name,
                                  'updated_at': cachevol_props['updated_at'],
                                  'numclones': cache_vol['numclones']})
                LOG.error(exception_msg)
                raise exception.VolumeBackendAPIException(data=exception_msg)

            # The cache volume is updated, but has no clone, so we delete it
            # and re-create a new one:
            super(ZFSSANFSDriver, self).delete_volume(cache_vol_obj)
            return self._create_cache_volume(context,
                                             img_meta,
                                             img_service,
                                             cachevol_props)

        return cachevol_name

    def _create_cache_volume(self, context, img_meta,
                             img_service, cachevol_props):
        """Create a cache volume from an image.

        Returns name of the cache volume.
        """
        lcfg = self.configuration
        cache_dir = '%s/' % lcfg.zfssa_cache_directory
        cache_vol = Volume()
        cache_vol.provider_location = self.mount_path
        cache_vol._name_id = cachevol_props['id']
        cache_vol.size = cachevol_props['size']
        cache_vol_name = cache_dir + cache_vol.name

        LOG.debug('Creating cache volume %s', cache_vol_name)
        try:
            self.create_volume(cache_vol)
            LOG.debug('Copying image data:')
            super(ZFSSANFSDriver, self).copy_image_to_volume(context,
                                                             cache_vol,
                                                             img_service,
                                                             img_meta['id'])
            self.zfssa.webdavclient.request(src_file=cache_vol.name,
                                            dst_file=cache_vol_name,
                                            method='MOVE')

        except Exception as exc:
            exc_msg = (_('Fail to create cache volume %(volume)s. '
                         'Error: %(err)s'),
                       {'volume': cache_vol_name,
                        'err': six.text_type(exc)})
            LOG.error(exc_msg)
            self.zfssa.delete_file(cache_vol_name)
            raise exception.VolumeBackendAPIException(data=exc_msg)

        cachevol_meta = {
            'updated_at': cachevol_props['updated_at'],
            'image_id': cachevol_props['image_id'],
        }
        cachevol_meta.update({'numclones': '0'})
        self.zfssa.set_file_props(cache_vol_name, cachevol_meta)
        return cache_vol_name

    def _create_snapshot_name(self):
        """Creates a snapshot name from the date and time."""

        return ('cinder-zfssa-nfs-snapshot-%s' %
                dt.datetime.utcnow().isoformat())

    def _get_share_capacity_info(self):
        """Get available and used capacity info for the NFS share."""
        lcfg = self.configuration
        share_details = self.zfssa.get_share(lcfg.zfssa_nfs_pool,
                                             lcfg.zfssa_nfs_project,
                                             lcfg.zfssa_nfs_share)

        free = share_details['space_available']
        used = share_details['space_total']
        return free, used

    @utils.synchronized('zfssanfs', external=True)
    def _check_origin(self, origin):
        """Verify the cache volume of a bootable volume.

        If the cache no longer has clone, it will be deleted.
        """
        try:
            cachevol_props = self.zfssa.get_volume(origin)
        except exception.VolumeNotFound:
            LOG.debug('Origin %s does not exist', origin)
            return

        numclones = cachevol_props['numclones']
        LOG.debug('Number of clones: %d', numclones)
        if numclones <= 1:
            # This cache vol does not have any other clone
            self.zfssa.delete_file(origin)
        else:
            cachevol_props = {'numclones': six.text_type(numclones - 1)}
            self.zfssa.set_file_props(origin, cachevol_props)

    def _update_origin(self, vol_name, cachevol_name):
        """Update WebDAV property of a volume.

        WebDAV properties are used to keep track of:
        (1) The number of clones of a cache volume.
        (2) The cache volume name (origin) of a bootable volume.

        To avoid race conditions when multiple volumes are created and needed
        to be updated, a file lock is used to ensure that the properties are
        updated properly.
        """
        volume_origin = {'origin': cachevol_name}
        self.zfssa.set_file_props(vol_name, volume_origin)

        cache_props = self.zfssa.get_volume(cachevol_name)
        cache_props.update({'numclones':
                            six.text_type(cache_props['numclones'] + 1)})
        self.zfssa.set_file_props(cachevol_name, cache_props)

    def _update_volume_stats(self):
        """Get volume stats from zfssa"""
        self._ensure_shares_mounted()
        data = {}
        lcfg = self.configuration
        backend_name = self.configuration.safe_get('volume_backend_name')
        data['volume_backend_name'] = backend_name or self.__class__.__name__
        data['vendor_name'] = 'Oracle'
        data['driver_version'] = self.VERSION
        data['storage_protocol'] = self.protocol

        asn = self.zfssa.get_asn()
        data['location_info'] = '%s:%s' % (asn, lcfg.zfssa_nfs_share)

        free, used = self._get_share_capacity_info()
        capacity = float(free) + float(used)
        ratio_used = used / capacity

        data['QoS_support'] = False
        data['reserved_percentage'] = 0

        used_percentage_limit = 100 - self.configuration.reserved_percentage
        used_ratio_limit = used_percentage_limit / 100.0
        if (ratio_used > used_ratio_limit or
                ratio_used >= self.configuration.max_over_subscription_ratio):
            data['reserved_percentage'] = 100

        data['total_capacity_gb'] = float(capacity) / units.Gi
        data['free_capacity_gb'] = float(free) / units.Gi

        share_details = self.zfssa.get_share(lcfg.zfssa_nfs_pool,
                                             lcfg.zfssa_nfs_project,
                                             lcfg.zfssa_nfs_share)
        pool_details = self.zfssa.get_pool_details(lcfg.zfssa_nfs_pool)

        data['zfssa_compression'] = share_details['compression']
        data['zfssa_encryption'] = share_details['encryption']
        data['zfssa_logbias'] = share_details['logbias']
        data['zfssa_poolprofile'] = pool_details['profile']
        data['zfssa_sparse'] = six.text_type(lcfg.nfs_sparsed_volumes)

        self._stats = data

    def migrate_volume(self, ctxt, volume, host):
        LOG.debug('Attempting ZFSSA enabled volume migration. volume: %(id)s, '
                  'host: %(host)s, status=%(status)s',
                  {'id': volume['id'],
                   'host': host,
                   'status': volume['status']})

        lcfg = self.configuration
        default_ret = (False, None)

        if volume['status'] != "available":
            LOG.debug('Only available volumes can be migrated using backend '
                      'assisted migration. Defaulting to generic migration.')
            return default_ret

        if (host['capabilities']['vendor_name'] != 'Oracle' or
                host['capabilities']['storage_protocol'] != self.protocol):
            LOG.debug('Source and destination drivers need to be Oracle iSCSI '
                      'to use backend assisted migration. Defaulting to '
                      'generic migration.')
            return default_ret

        if 'location_info' not in host['capabilities']:
            LOG.debug('Could not find location_info in capabilities reported '
                      'by the destination driver. Defaulting to generic '
                      'migration.')
            return default_ret

        loc_info = host['capabilities']['location_info']

        try:
            (tgt_asn, tgt_share) = loc_info.split(':')
        except ValueError:
            LOG.error("Location info needed for backend enabled volume "
                      "migration not in correct format: %s. Continuing "
                      "with generic volume migration.", loc_info)
            return default_ret

        src_asn = self.zfssa.get_asn()

        if tgt_asn == src_asn and lcfg.zfssa_nfs_share == tgt_share:
            LOG.info('Source and destination ZFSSA shares are the same. '
                     'Do nothing. volume: %s', volume['name'])
            return (True, None)

        return (False, None)

    def update_migrated_volume(self, ctxt, volume, new_volume,
                               original_volume_status):
        """Return model update for migrated volume.

        :param volume: The original volume that was migrated to this backend
        :param new_volume: The migration volume object that was created on
                           this backend as part of the migration process
        :param original_volume_status: The status of the original volume
        :returns: model_update to update DB with any needed changes
        """

        original_name = CONF.volume_name_template % volume['id']
        current_name = CONF.volume_name_template % new_volume['id']

        LOG.debug('Renaming migrated volume: %(cur)s to %(org)s.',
                  {'cur': current_name,
                   'org': original_name})
        self.zfssa.create_volume_from_snapshot_file(src_file=current_name,
                                                    dst_file=original_name,
                                                    method='MOVE')
        provider_location = new_volume['provider_location']
        return {'_name_id': None, 'provider_location': provider_location}

    def manage_existing(self, volume, existing_ref):
        """Manage an existing volume in the ZFSSA backend.

        :param volume: Reference to the new volume.
        :param existing_ref: Reference to the existing volume to be managed.
        """
        existing_vol_name = self._get_existing_vol_name(existing_ref)
        try:
            vol_props = self.zfssa.get_volume(existing_vol_name)
        except exception.VolumeNotFound:
            err_msg = (_("Volume %s doesn't exist on the ZFSSA backend.") %
                       existing_vol_name)
            LOG.error(err_msg)
            raise exception.InvalidInput(reason=err_msg)

        self._verify_volume_to_manage(existing_vol_name, vol_props)

        try:
            self.zfssa.rename_volume(existing_vol_name, volume['name'])
        except Exception:
            LOG.error("Failed to rename volume %(existing)s to %(new)s. "
                      "Volume manage failed.",
                      {'existing': existing_vol_name,
                       'new': volume['name']})
            raise

        try:
            self.zfssa.set_file_props(volume['name'],
                                      {'cinder_managed': 'True'})
        except Exception:
            self.zfssa.rename_volume(volume['name'], existing_vol_name)
            LOG.error("Failed to set properties for volume %(existing)s. "
                      "Volume manage failed.",
                      {'existing': volume['name']})
            raise

        return {'provider_location': self.mount_path}

    def manage_existing_get_size(self, volume, existing_ref):
        """Return size of the volume to be managed by manage_existing."""
        existing_vol_name = self._get_existing_vol_name(existing_ref)

        # The ZFSSA NFS driver only has one mounted share.
        local_share_mount = self._get_mount_point_for_share(
            self._mounted_shares[0])
        local_vol_path = os.path.join(local_share_mount, existing_vol_name)

        try:
            if os.path.isfile(local_vol_path):
                size = int(math.ceil(float(
                    utils.get_file_size(local_vol_path)) / units.Gi))
        except (OSError, ValueError):
            err_msg = (_("Failed to get size of existing volume: %(vol)s. "
                         "Volume Manage failed."), {'vol': existing_vol_name})
            LOG.error(err_msg)
            raise exception.VolumeBackendAPIException(data=err_msg)

        LOG.debug("Size volume: %(vol)s to be migrated is: %(size)s.",
                  {'vol': existing_vol_name, 'size': size})

        return size

    def _verify_volume_to_manage(self, name, vol_props):
        lcfg = self.configuration

        if lcfg.zfssa_manage_policy != 'strict':
            return

        if vol_props['cinder_managed'] == "":
            err_msg = (_("Unknown if the volume: %s to be managed is "
                         "already being managed by Cinder. Aborting manage "
                         "volume. Please add 'cinder_managed' custom schema "
                         "property to the volume and set its value to False. "
                         "Alternatively, Set the value of cinder config "
                         "policy 'zfssa_manage_policy' to 'loose' to "
                         "remove this restriction.") % name)
            LOG.error(err_msg)
            raise exception.InvalidInput(reason=err_msg)

        if vol_props['cinder_managed'] == 'True':
            msg = (_("Volume: %s is already being managed by Cinder.") % name)
            LOG.error(msg)
            raise exception.ManageExistingAlreadyManaged(volume_ref=name)

    def unmanage(self, volume):
        """Remove an existing volume from cinder management.

        :param volume: Reference to the volume to be unmanaged.
        """
        new_name = 'unmanaged-' + volume['name']
        try:
            self.zfssa.rename_volume(volume['name'], new_name)
        except Exception:
            LOG.error("Failed to rename volume %(existing)s to %(new)s. "
                      "Volume unmanage failed.",
                      {'existing': volume['name'],
                       'new': new_name})
            raise

        try:
            self.zfssa.set_file_props(new_name, {'cinder_managed': 'False'})
        except Exception:
            self.zfssa.rename_volume(new_name, volume['name'])
            LOG.error("Failed to set properties for volume %(existing)s. "
                      "Volume unmanage failed.",
                      {'existing': volume['name']})
            raise

    def _get_existing_vol_name(self, existing_ref):
        if 'source-name' not in existing_ref:
            msg = _("Reference to volume to be managed must contain "
                    "source-name.")
            raise exception.ManageExistingInvalidReference(
                existing_ref=existing_ref, reason=msg)
        return existing_ref['source-name']
