Example #1
0
    def _start_backend(self):
        """
        Load and start backend subsystem once
        """
        if not self.backend:

            # Start the selected config backend system.
            self.backend = BackendRegistry().selected()
            if self.backend:
                self.backend.start()

        return self.backend
Example #2
0
    def cmd_show_storage(self):
        """Show storage info"""

        backend = BackendRegistry().selected()
        if not backend:
            # no backend? check to be sure
            assert Globals().get_backend() == "None", \
                    "Error: please check your storage backend configuration" \
                    "(backend=%s)" % Globals().get_backend()
            print "Storage backend is disabled, please check storage " \
                  "information as a per-filesystem basis with ``show info''."
        else:
            backend.start() 
            cnt = 0
            for tgt in [ 'mgt', 'mdt', 'ost']:
                for dev in backend.get_target_devices(tgt):
                    print dev
                    cnt += 1
            print "Total: %d devices" % cnt
        return 0
Example #3
0
    def cmd_show_storage(self):
        """Show storage info"""

        backend = BackendRegistry().selected()
        if not backend:
            # no backend? check to be sure
            assert Globals().get_backend() == "None", \
                    "Error: please check your storage backend configuration" \
                    "(backend=%s)" % Globals().get_backend()
            print("Storage backend is disabled, please check storage "
                  "information as a per-filesystem basis with ``show info''.")
        else:
            backend.start()
            cnt = 0
            for tgt in ['mgt', 'mdt', 'ost']:
                for dev in backend.get_target_devices(tgt):
                    print(dev)
                    cnt += 1
            print("Total: %d devices" % cnt)
        return 0
Example #4
0
    def _start_backend(self):
        """
        Load and start backend subsystem once
        """
        if not self.backend:

            # Start the selected config backend system.
            self.backend = BackendRegistry().selected()
            if self.backend:
                self.backend.start()

        return self.backend
Example #5
0
class FileSystem(object):
    """
    Lustre File System Configuration class.
    """
    def __init__(self, filename):

        self.backend = None
        self.xmf_path = None
        self.model = Model()

        try:
            self.model.load(filename)
        except IOError:
            raise ModelFileIOError("Could not read %s" % filename)

        # Set nodes to nids mapping using the NidMap helper class
        self.nid_map = NidMap.fromlist(self.get('nid_map'))

        # Initialize the tuning model to None if no special tuning configuration
        # is provided
        self.tuning_model = TuningModel()

    @property
    def fs_name(self):
        return self.get('fs_name')

    def get(self, key, default=None):
        """Return the Model value pointed by `key'"""
        return self.model.get(key, default)

    @classmethod
    def _cache_path(cls, fsname):
        """Build and check a cache file path from filesystem name."""
        fs_conf_dir = os.path.expandvars(Globals().get_conf_dir())
        if not os.path.exists(fs_conf_dir):
            raise ConfigException("Cache directory does not exist '%s'" %
                                  fs_conf_dir)
        return "%s/%s.xmf" % (os.path.normpath(fs_conf_dir), fsname)

    @classmethod
    def create_from_model(cls, lmf, update_mode=False):
        """Save to cache."""
        fsmodel = FileSystem(lmf)
        # xmf_path could be set later if setup_target_devices do not need it
        fsmodel.xmf_path = cls._cache_path(fsmodel.fs_name)
        fsmodel.setup_target_devices(update_mode=update_mode)
        # Save XMF
        fsmodel.model.save(fsmodel.xmf_path,
                  "# Shine Lustre file system config file for %s" % \
                  fsmodel.fs_name)

        # Reload from content saved previously
        return cls.load_from_fsname(fsmodel.fs_name)

    @classmethod
    def load_from_fsname(cls, fsname):
        """Load from cache."""
        conf_file = cls._cache_path(fsname)
        fsconf = FileSystem(conf_file)
        fsconf.xmf_path = conf_file
        return fsconf

    def _start_backend(self):
        """
        Load and start backend subsystem once
        """
        if not self.backend:

            # Start the selected config backend system.
            self.backend = BackendRegistry().selected()
            if self.backend:
                self.backend.start()

        return self.backend

    def setup_target_devices(self, update_mode=False):
        """ Generate the eXtended Model File XMF """

        self._start_backend()

        # We have to setup the possible targets, which are: MGT, MDT and OST.
        for target in ['mgt', 'mdt', 'ost']:

            # So, first, look for which ones are defined in model
            if target not in self.model:
                continue

            # Lustre supports up to FFFF targets per type.
            indexes = range(0, 65535)

            if self.backend:

                # Returns a list of TargetDevices
                fs_name = None
                if update_mode == True:
                    fs_name = self.fs_name
                candidates = self.backend.get_target_devices(
                    target, fs_name=fs_name, update_mode=update_mode)

                # Save the model target selection
                target_models = copy.copy(self.model.get(target))

                # Reduce entropy from backend.
                # (node, dev) should point to a unique device, so this should
                # be enough for sorting. This is not perfect but enough to have
                # a very low entropy in result order.
                candidates.sort(key=lambda x: (x.get('node'), x.get('dev')))

                # Delete it (to be replaced... see below)
                self.model.elements(target).clear()

                try:

                    # Remove already used index from candidate list.
                    for target_model in target_models:
                        if 'index' in target_model:
                            idx = target_model.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Iterates on each Model.Target
                    for target_model in target_models:

                        # Do not try to match external components
                        if target_model.get('mode') == 'external':
                            self.model.elements(target).parse(
                                str(target_model))
                            continue

                        result = target_model.match_device(candidates)
                        if len(result) == 0:
                            raise ConfigDeviceNotFoundError(target_model)

                        for matching in result:
                            candidates.remove(matching)

                            # If an index was specified, set it.
                            if 'index' in target_model:
                                matching.add_index(target_model.get('index'))
                                target_model.elements('index').clear()

                            # Manage index, mandatoy in XMF files
                            if not matching.has_index():
                                matching.add_index(indexes[0])
                                idx = matching.index()
                                # List raises ValueError and we need to know
                                # the missing indexes here, so we had this
                                # hack.
                                if idx not in indexes:
                                    raise KeyError(idx)
                                indexes.remove(idx)

                            # Copy properties from model
                            # which do not exist in backend.
                            matching.add_active(target_model.get('active'))

                            # `matching' is a TargetDevice, we want to add it
                            # to the underlying Model object. The current way
                            # to do this to create a configuration line string
                            # (performed by TargetDevice.getline()) and then
                            # call Model.parse().
                            # TODO: add methods to Model/ModelDevice to avoid
                            #  the use of temporary configuration string line.
                            self.model.elements(target).parse(
                                matching.getline())

                except KeyError, error:
                    raise ConfigInvalidFileSystem(self, \
                            "Index %s for %s used twice." % \
                            (str(error), target))

            # Support for backend None
            else:

                try:
                    # Remove already used indexes from candidate list.
                    for params in self.model.elements(target):
                        if 'index' in params:
                            idx = params.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Manage index
                    for params in self.model.elements(target):
                        if 'index' not in params:
                            params.add('index', str(indexes[0]))
                            indexes.remove(indexes[0])

                except KeyError, error:
                    raise ConfigInvalidFileSystem(self, \
                             "Index %s for %s used twice." % \
                              (str(error), target))
Example #6
0
class FileSystem(object):
    """
    Lustre File System Configuration class.
    """

    def __init__(self, filename):

        self.backend = None
        self.xmf_path = None
        self.model = Model()

        try:
            self.model.load(filename)
        except IOError:
            raise ModelFileIOError("Could not read %s" % filename)

        # Set nodes to nids mapping using the NidMap helper class
        self.nid_map = NidMap.fromlist(self.get('nid_map'))

        # Initialize the tuning model to None if no special tuning configuration
        # is provided
        self.tuning_model = TuningModel()

    @property
    def fs_name(self):
        return self.get('fs_name')

    def get(self, key, default=None):
        """Return the Model value pointed by `key'"""
        return self.model.get(key, default)

    @classmethod
    def _cache_path(cls, fsname):
        """Build and check a cache file path from filesystem name."""
        fs_conf_dir = os.path.expandvars(Globals().get_conf_dir())
        if not os.path.exists(fs_conf_dir):
            raise ConfigException("Cache directory does not exist '%s'" % 
                                  fs_conf_dir)
        return "%s/%s.xmf" % (os.path.normpath(fs_conf_dir), fsname)

    @classmethod
    def create_from_model(cls, lmf, update_mode=False):
        """Save to cache."""
        fsmodel = FileSystem(lmf)
        # xmf_path could be set later if setup_target_devices do not need it
        fsmodel.xmf_path = cls._cache_path(fsmodel.fs_name)
        fsmodel.setup_target_devices(update_mode=update_mode)
        # Save XMF
        fsmodel.model.save(fsmodel.xmf_path,
                  "# Shine Lustre file system config file for %s" % \
                  fsmodel.fs_name)

        # Reload from content saved previously
        return cls.load_from_fsname(fsmodel.fs_name)

    @classmethod
    def load_from_fsname(cls, fsname):
        """Load from cache."""
        conf_file = cls._cache_path(fsname)
        fsconf = FileSystem(conf_file)
        fsconf.xmf_path = conf_file
        return fsconf


    def _start_backend(self):
        """
        Load and start backend subsystem once
        """
        if not self.backend:

            # Start the selected config backend system.
            self.backend = BackendRegistry().selected()
            if self.backend:
                self.backend.start()

        return self.backend

    def setup_target_devices(self, update_mode=False):
        """ Generate the eXtended Model File XMF """

        self._start_backend()

        # We have to setup the possible targets, which are: MGT, MDT and OST.
        for target in [ 'mgt', 'mdt', 'ost' ]:

            # So, first, look for which ones are defined in model
            if target not in self.model:
                continue

            # Lustre supports up to FFFF targets per type.
            indexes = range(0, 65535)

            if self.backend:

                # Returns a list of TargetDevices
                fs_name = None
                if update_mode == True:
                    fs_name = self.fs_name
                candidates = self.backend.get_target_devices(target,
                                      fs_name=fs_name, update_mode=update_mode)

                # Save the model target selection
                target_models = copy.copy(self.model.get(target))

                # Reduce entropy from backend.
                # (node, dev) should point to a unique device, so this should
                # be enough for sorting. This is not perfect but enough to have
                # a very low entropy in result order.
                candidates.sort(key=lambda x: (x.get('node'), x.get('dev')))

                # Delete it (to be replaced... see below)
                self.model.elements(target).clear()

                try:

                    # Remove already used index from candidate list.
                    for target_model in target_models:
                        if 'index' in target_model:
                            idx = target_model.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Iterates on each Model.Target
                    for target_model in target_models:

                        # Do not try to match external components
                        if target_model.get('mode') == 'external':
                            self.model.elements(target).parse(str(target_model))
                            continue

                        result = target_model.match_device(candidates)
                        if len(result) == 0:
                            raise ConfigDeviceNotFoundError(target_model)

                        for matching in result:
                            candidates.remove(matching)

                            # If an index was specified, set it.
                            if 'index' in target_model:
                                matching.add_index(target_model.get('index'))
                                target_model.elements('index').clear()

                            # Manage index, mandatoy in XMF files
                            if not matching.has_index():
                                matching.add_index(indexes[0])
                                idx = matching.index()
                                # List raises ValueError and we need to know
                                # the missing indexes here, so we had this
                                # hack.
                                if idx not in indexes:
                                    raise KeyError(idx)
                                indexes.remove(idx)

                            # Copy properties from model
                            # which do not exist in backend.
                            matching.add_active(target_model.get('active'))

                            # `matching' is a TargetDevice, we want to add it
                            # to the underlying Model object. The current way
                            # to do this to create a configuration line string
                            # (performed by TargetDevice.getline()) and then
                            # call Model.parse(). 
                            # TODO: add methods to Model/ModelDevice to avoid
                            #  the use of temporary configuration string line.
                            self.model.elements(target).parse(
                                                            matching.getline())

                except KeyError, error:
                    raise ConfigInvalidFileSystem(self, \
                            "Index %s for %s used twice." % \
                            (str(error), target))

            # Support for backend None
            else:

                try:
                    # Remove already used indexes from candidate list.
                    for params in self.model.elements(target):
                        if 'index' in params:
                            idx = params.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Manage index
                    for params in self.model.elements(target):
                        if 'index' not in params:
                            params.add('index', str(indexes[0]))
                            indexes.remove(indexes[0])

                except KeyError, error:
                    raise ConfigInvalidFileSystem(self, \
                             "Index %s for %s used twice." % \
                              (str(error), target))
Example #7
0
class FileSystem(object):
    """
    Lustre File System Configuration class.
    """
    def __init__(self, filename):

        self.backend = None
        self.xmf_path = None
        self.model = Model()

        try:
            self.model.load(filename)
        except IOError:
            raise ModelFileIOError("Could not read %s" % filename)

        # Model expands nid_map automatically, just iterate other them
        self.nid_map = {}
        for elem in self.get('nid_map'):
            self.nid_map.setdefault(elem['nodes'], []).append(elem['nids'])

        # Initialize the tuning model to None if no special tuning configuration
        # is provided
        self.tuning_model = TuningModel()

    @property
    def fs_name(self):
        return self.get('fs_name')

    def get(self, key, default=None):
        """Return the Model value pointed by `key'"""
        return self.model.get(key, default)

    @classmethod
    def _cache_path(cls, fsname):
        """Build and check a cache file path from filesystem name."""
        fs_conf_dir = os.path.expandvars(Globals().get_conf_dir())
        if not os.path.exists(fs_conf_dir):
            raise ConfigException("Cache directory does not exist '%s'" %
                                  fs_conf_dir)
        return "%s/%s.xmf" % (os.path.normpath(fs_conf_dir), fsname)

    @classmethod
    def create_from_model(cls, lmf, update_mode=False):
        """Save to cache."""
        fsmodel = FileSystem(lmf)
        # xmf_path could be set later if setup_target_devices do not need it
        fsmodel.xmf_path = cls._cache_path(fsmodel.fs_name)
        fsmodel.setup_target_devices(update_mode=update_mode)
        # Save XMF
        fsmodel.model.save(fsmodel.xmf_path,
                  "# Shine Lustre file system config file for %s" % \
                  fsmodel.fs_name)

        # Reload from content saved previously
        return cls.load_from_fsname(fsmodel.fs_name)

    @classmethod
    def load_from_fsname(cls, fsname):
        """Load from cache."""
        conf_file = cls._cache_path(fsname)
        fsconf = FileSystem(conf_file)
        fsconf.xmf_path = conf_file
        return fsconf

    def _start_backend(self):
        """
        Load and start backend subsystem once
        """
        if not self.backend:

            # Start the selected config backend system.
            self.backend = BackendRegistry().selected()
            if self.backend:
                self.backend.start()

        return self.backend

    def setup_target_devices(self, update_mode=False):
        """ Generate the eXtended Model File XMF """

        self._start_backend()

        # We have to setup the possible targets, which are: MGT, MDT and OST.
        for target in ['mgt', 'mdt', 'ost']:

            # So, first, look for which ones are defined in model
            if target not in self.model:
                continue

            # Lustre supports up to FFFF targets per type.
            indexes = list(range(0, 65535))

            if self.backend:

                # Returns a list of TargetDevices
                fs_name = None
                if update_mode == True:
                    fs_name = self.fs_name
                candidates = self.backend.get_target_devices(
                    target, fs_name=fs_name, update_mode=update_mode)

                # Save the model target selection
                target_models = copy.copy(self.model.get(target))

                # Reduce entropy from backend.
                # (node, dev) should point to a unique device, so this should
                # be enough for sorting. This is not perfect but enough to have
                # a very low entropy in result order.
                candidates.sort(key=lambda x: (x.get('node'), x.get('dev')))

                # Delete it (to be replaced... see below)
                self.model.elements(target).clear()

                try:

                    # Remove already used index from candidate list.
                    for target_model in target_models:
                        if 'index' in target_model:
                            idx = target_model.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Iterates on each Model.Target
                    for target_model in target_models:

                        # Do not try to match external components
                        if target_model.get('mode') == 'external':
                            self.model.elements(target).parse(
                                str(target_model))
                            continue

                        result = target_model.match_device(candidates)
                        if len(result) == 0:
                            raise ConfigDeviceNotFoundError(target_model)

                        for matching in result:
                            candidates.remove(matching)

                            # If an index was specified, set it.
                            if 'index' in target_model:
                                matching.add_index(target_model.get('index'))
                                target_model.elements('index').clear()

                            # Manage index, mandatoy in XMF files
                            if not matching.has_index():
                                matching.add_index(indexes[0])
                                idx = matching.index()
                                # List raises ValueError and we need to know
                                # the missing indexes here, so we had this
                                # hack.
                                if idx not in indexes:
                                    raise KeyError(idx)
                                indexes.remove(idx)

                            # Copy properties from model
                            # which do not exist in backend.
                            matching.add_active(target_model.get('active'))

                            # `matching' is a TargetDevice, we want to add it
                            # to the underlying Model object. The current way
                            # to do this to create a configuration line string
                            # (performed by TargetDevice.getline()) and then
                            # call Model.parse().
                            # TODO: add methods to Model/ModelDevice to avoid
                            #  the use of temporary configuration string line.
                            self.model.elements(target).parse(
                                matching.getline())

                except KeyError as error:
                    raise ConfigInvalidFileSystem(self, \
                            "Index %s for %s used twice." % \
                            (str(error), target))

            # Support for backend None
            else:

                try:
                    # Remove already used indexes from candidate list.
                    for params in self.model.elements(target):
                        if 'index' in params:
                            idx = params.get('index')
                            # List raises ValueError and we need to know the
                            # missing indexes here, so we had this hack.
                            if idx not in indexes:
                                raise KeyError(idx)
                            indexes.remove(idx)

                    # Manage index
                    for params in self.model.elements(target):
                        if 'index' not in params:
                            params.add('index', str(indexes[0]))
                            indexes.remove(indexes[0])

                except KeyError as error:
                    raise ConfigInvalidFileSystem(self, \
                             "Index %s for %s used twice." % \
                              (str(error), target))

        self._check_coherency()

    def _check_coherency(self):
        """Verify that the declared components make a coherent filesystem."""

        model = self.model
        # If we have a target or a client, we need a MGT
        if (('client' in model or 'mdt' in model or 'ost' in model) \
            and not ('mgt' in model)):
            raise ConfigInvalidFileSystem(self, "A MGS must be declared.")

        # We should have both MDT and OST or neither
        if ('mdt' in model) ^ ('ost' in model):
            raise ConfigInvalidFileSystem(
                self, "You must declare both MDT and OST or neither.")

    def compare(self, otherfs):
        """
        Compare the FileSystem model with another FileSystem and return
        a dictionnary describing the needed actions.
        """

        actions = {}
        added, changed, removed = self.model.diff(otherfs.model)

        anyset = set(changed.keys()) | set(added.keys()) \
                  | set(removed.keys())

        # Read-only keys: fs_name
        readonly = set(['fs_name'])
        if readonly & anyset:
            raise ConfigException("%s could not be changed" %
                                  ", ".join(readonly & anyset))

        # Need to reformat targets
        reformatkeys = set([
            'mgt_mkfs_options', 'mdt_mkfs_options', 'ost_mkfs_options',
            'mgt_format_params', 'mdt_format_params', 'ost_format_params'
        ])
        if reformatkeys & anyset:
            actions['reformat'] = True

        # Need a tunefs.lustre
        tunefskeys = set([
            'quota', 'quota_type', 'quota_bunit', 'quota_iunit', 'quota_btune',
            'quota_itune', 'stripe_size', 'stripe_count'
        ])
        if tunefskeys & anyset:
            actions['tunefs'] = True

        # Need a writeconf
        writeconfkeys = set(['nid_map'])
        if writeconfkeys & anyset:
            hosts = set()
            for content in (added, changed, removed):
                hosts |= set([
                    elem.get('nodes') for elem in content.elements('nid_map')
                ])

            for tag in ('mgt', 'mdt', 'ost'):
                for tgt in self.model.get(tag, []):
                    if tgt.get('node') in hosts:
                        # Note: Target removal could also set this flag.
                        actions['writeconf'] = True
                        break

        # Need to unmount then remount clients
        remountkeys = set(['mount_options', 'mount_path', 'subdir'])
        if remountkeys & anyset:
            actions['copyconf'] = True
            # Could be improved if doing this only on clients without specific
            # path or options.
            if self.model.get('client'):
                actions['unmount'] = [
                    Clients(cli) for cli in self.model.get('client')
                ]
            if otherfs.model.get('client'):
                actions['mount'] = [
                    Clients(cli) for cli in otherfs.model.get('client')
                ]

        # Need to restart targets
        restartkeys = set([
            'mgt_mount_path', 'mdt_mount_path', 'ost_mount_path',
            'mgt_mount_options', 'mdt_mount_options', 'ost_mount_options'
        ])
        if restartkeys & anyset:
            actions['restart'] = True

        # Only need to update cache file
        copykeys = set(['description'])
        if copykeys & anyset:
            actions['copyconf'] = True

        # Clients have changed
        if 'client' in removed:
            actions.setdefault('unmount', [])
            actions['unmount'] += [
                Clients(elem) for elem in removed.elements('client')
            ]
        if 'client' in added:
            actions.setdefault('mount', [])
            actions['mount'] += [
                Clients(elem) for elem in added.elements('client')
            ]

        if 'client' in changed:
            for elem in changed.elements('client'):
                actions.setdefault('unmount', []).append(Clients(elem.old))
                actions.setdefault('mount', []).append(Clients(elem))

        # Router has changed
        if 'router' in removed:
            actions.setdefault('stop', []).extend(
                [Routers(elem) for elem in removed.elements('router')])
        if 'router' in added:
            actions.setdefault('start', []).extend(
                [Routers(elem) for elem in added.elements('router')])
        assert 'router' not in changed, 'Router change is not supported'

        # Some targets have changed
        for tgt in ['mgt', 'mdt', 'ost']:
            if tgt in removed:
                actions['writeconf'] = True
                actions.setdefault('stop', []).extend(
                    [Target(tgt, elem) for elem in removed.elements(tgt)])
                actions.setdefault('remove', []).extend(
                    [Target(tgt, elem) for elem in removed.elements(tgt)])
            if tgt in added:
                actions.setdefault('format', []).extend(
                    [Target(tgt, elem) for elem in added.elements(tgt)])
                actions.setdefault('start', []).extend(
                    [Target(tgt, elem) for elem in added.elements(tgt)])
            if tgt in changed:
                for elem in changed.elements(tgt):
                    if set(['ha_node', 'network', 'node', 'dev']) & \
                       elem.chgkeys:
                        actions.setdefault('stop',
                                           []).append(Target(tgt, elem.old))
                        actions.setdefault('start',
                                           []).append(Target(tgt, elem))

                    if set(['ha_node', 'network', 'node']) & elem.chgkeys:
                        actions['writeconf'] = True

                    if set(['tag', 'group']) & elem.chgkeys:
                        actions['copyconf'] = True

                    if 'active' in elem.chgkeys:
                        actions['tune'] = True

                    if 'jdev' in elem.chgkeys:
                        raise ConfigException("'jdev' change is not supported")

        # If some actions is required, we need to update config files.
        if len(actions) > 0:
            actions['copyconf'] = True

        return actions

    def get_nid(self, node):
        try:
            return self.nid_map[node]
        except KeyError:
            raise ConfigException("Cannot get NID for %s, aborting. Please "
                                  "verify `nid_map' configuration." % node)

    def close(self):
        if self.backend:
            self.backend.stop()
            self.backend = None

    def register(self):
        """
        This function aims to register the file system configuration
        to the backend.
        """
        if self._start_backend():
            return self.backend.register_fs(self)

    def unregister(self):
        """
        This function aims to remove a file system configuration from
        the backend.
        """
        result = 0
        if self._start_backend():
            result = self.backend.unregister_fs(self)

        # XMF file could have been already deleted if this is a local
        # filesystem
        if os.path.exists(self.xmf_path) and not result:
            os.unlink(self.xmf_path)

        return result

    def register_target(self, target):
        """
        Set the specified target as 'in use'.

        This target could not be use anymore for other filesystems.
        """
        if self._start_backend():
            return self.backend.register_target(self, target)

    def unregister_target(self, target):
        """
        Set the specified target as available in the backend.

        This target could be now reuse.
        """
        if self._start_backend():
            return self.backend.unregister_target(self, target)