lvm.py

# devices/lvm.py
#
# Copyright (C) 2009-2014  Red Hat, Inc.
#
# This copyrighted material is made available to anyone wishing to use,
# modify, copy, or redistribute it subject to the terms and conditions of
# the GNU General Public License v.2, or (at your option) any later version.
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY expressed or implied, including the implied warranties of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
# Public License for more details.  You should have received a copy of the
# GNU General Public License along with this program; if not, write to the
# Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.  Any Red Hat trademarks that are incorporated in the
# source code or documentation are not subject to the GNU General Public
# License and may only be used or replicated with the express permission of
# Red Hat, Inc.
#
# Red Hat Author(s): David Lehman <dlehman@redhat.com>
#

from decimal import Decimal
from six import add_metaclass
import abc
import pprint
import re
import os
from gi.repository import BlockDev as blockdev

# device backend modules
from ..devicelibs import lvm

from .. import errors
from .. import util
from ..formats import getFormat
from ..storage_log import log_method_call
from .. import udev
from ..size import Size, KiB, MiB, ROUND_UP, ROUND_DOWN
from ..tasks import availability

import logging
log = logging.getLogger("blivet")

from .lib import LINUX_SECTOR_SIZE, ParentList
from .device import Device
from .storage import StorageDevice
from .container import ContainerDevice
from .dm import DMDevice
from .md import MDRaidArrayDevice

_INTERNAL_LV_CLASSES = []

def get_internal_lv_class(lv_attr):
    # XXX: need to do some heuristic on the LV name?
    for cls in _INTERNAL_LV_CLASSES:
        if lv_attr[0] in cls.attr_letters:
            return cls

    return None

class LVMVolumeGroupDevice(ContainerDevice):
    """ An LVM Volume Group """
    _type = "lvmvg"
    _packages = ["lvm2"]
    _formatClassName = property(lambda s: "lvmpv")
    _formatUUIDAttr = property(lambda s: "vgUuid")
    _formatImmutable = True

    @staticmethod
    def get_supported_pe_sizes():
        return [Size(pe_size) for pe_size in blockdev.lvm.get_supported_pe_sizes()]

    def __init__(self, name, parents=None, size=None, free=None,
                 peSize=None, peCount=None, peFree=None, pvCount=None,
                 uuid=None, exists=False, sysfsPath=''):
        """
            :param name: the device name (generally a device node's basename)
            :type name: str
            :keyword exists: does this device exist?
            :type exists: bool
            :keyword parents: a list of parent devices
            :type parents: list of :class:`StorageDevice`
            :keyword sysfsPath: sysfs device path
            :type sysfsPath: str
            :keyword peSize: physical extent size
            :type peSize: :class:`~.size.Size`

            For existing VG's only:

            :keyword size: the VG's size
            :type size: :class:`~.size.Size`
            :keyword free -- amount of free space in the VG
            :type free: :class:`~.size.Size`
            :keyword peFree: number of free extents
            :type peFree: int
            :keyword peCount -- total number of extents
            :type peCount: int
            :keyword pvCount: number of PVs in this VG
            :type pvCount: int
            :keyword uuid: the VG UUID
            :type uuid: str
        """
        # These attributes are used by _addParent, so they must be initialized
        # prior to instantiating the superclass.
        self._lvs = []
        self.hasDuplicate = False
        self._complete = False  # have we found all of this VG's PVs?
        self.pvCount = util.numeric_type(pvCount)
        if exists and not pvCount:
            self._complete = True

        super(LVMVolumeGroupDevice, self).__init__(name, parents=parents,
                                            uuid=uuid, size=size,
                                            exists=exists, sysfsPath=sysfsPath)

        self.free = util.numeric_type(free)
        self.peSize = util.numeric_type(peSize)
        self.peCount = util.numeric_type(peCount)
        self.peFree = util.numeric_type(peFree)
        self.reserved_percent = 0
        self.reserved_space = Size(0)

        # TODO: validate peSize if given
        if not self.peSize:
            self.peSize = lvm.LVM_PE_SIZE

        if not self.exists:
            self.pvCount = len(self.parents)

        # >0 is fixed
        self.size_policy = self.size

    def __repr__(self):
        s = super(LVMVolumeGroupDevice, self).__repr__()
        s += ("  free = %(free)s  PE Size = %(peSize)s  PE Count = %(peCount)s\n"
              "  PE Free = %(peFree)s  PV Count = %(pvCount)s\n"
              "  modified = %(modified)s"
              "  extents = %(extents)s  free space = %(freeSpace)s\n"
              "  free extents = %(freeExtents)s"
              "  reserved percent = %(rpct)s  reserved space = %(res)s\n"
              "  PVs = %(pvs)s\n"
              "  LVs = %(lvs)s" %
              {"free": self.free, "peSize": self.peSize, "peCount": self.peCount,
               "peFree": self.peFree, "pvCount": self.pvCount,
               "modified": self.isModified,
               "extents": self.extents, "freeSpace": self.freeSpace,
               "freeExtents": self.freeExtents,
               "rpct": self.reserved_percent, "res": self.reserved_space,
               "pvs": pprint.pformat([str(p) for p in self.pvs]),
               "lvs": pprint.pformat([str(l) for l in self.lvs])})
        return s

    @property
    def dict(self):
        d = super(LVMVolumeGroupDevice, self).dict
        d.update({"free": self.free, "peSize": self.peSize,
                  "peCount": self.peCount, "peFree": self.peFree,
                  "pvCount": self.pvCount, "extents": self.extents,
                  "freeSpace": self.freeSpace,
                  "freeExtents": self.freeExtents,
                  "reserved_percent": self.reserved_percent,
                  "reserved_space": self.reserved_space,
                  "lvNames": [lv.name for lv in self.lvs]})
        return d

    @property
    def mapName(self):
        """ This device's device-mapper map name """
        # Thank you lvm for this lovely hack.
        return self.name.replace("-","--")

    @property
    def path(self):
        """ Device node representing this device. """
        return "%s/%s" % (self._devDir, self.mapName)

    def updateSysfsPath(self):
        """ Update this device's sysfs path. """
        log_method_call(self, self.name, status=self.status)
        if not self.exists:
            raise errors.DeviceError("device has not been created", self.name)

        self.sysfsPath = ''

    @property
    def status(self):
        """ The device's status (True means active). """
        if not self.exists:
            return False

        # certainly if any of this VG's LVs are active then so are we
        for lv in self.lvs:
            if lv.status:
                return True

        # if any of our PVs are not active then we cannot be
        for pv in self.pvs:
            if not pv.status:
                return False

        # if we are missing some of our PVs we cannot be active
        if not self.complete:
            return False

        return True

    def _preSetup(self, orig=False):
        if self.exists and not self.complete:
            raise errors.DeviceError("cannot activate VG with missing PV(s)", self.name)
        return StorageDevice._preSetup(self, orig=orig)

    def _teardown(self, recursive=None):
        """ Close, or tear down, a device. """
        log_method_call(self, self.name, status=self.status,
                        controllable=self.controllable)
        blockdev.lvm.vgdeactivate(self.name)

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        pv_list = [pv.path for pv in self.parents]
        blockdev.lvm.vgcreate(self.name, pv_list, self.peSize)

    def _postCreate(self):
        self._complete = True
        super(LVMVolumeGroupDevice, self)._postCreate()

    def _preDestroy(self):
        StorageDevice._preDestroy(self)
        # set up the pvs since lvm needs access to them to do the vgremove
        self.setupParents(orig=True)

    def _destroy(self):
        """ Destroy the device. """
        log_method_call(self, self.name, status=self.status)
        if not self.complete:
            for pv in self.pvs:
                # Remove the PVs from the ignore filter so we can wipe them.
                lvm.lvm_cc_removeFilterRejectRegexp(pv.name)

            # Don't run vgremove or vgreduce since there may be another VG with
            # the same name that we want to keep/use.
            return

        blockdev.lvm.vgreduce(self.name, None)
        blockdev.lvm.vgdeactivate(self.name)
        blockdev.lvm.vgremove(self.name)

    def _remove(self, member):
        status = []
        for lv in self.lvs:
            status.append(lv.status)
            if lv.exists:
                lv.setup()

        blockdev.lvm.pvmove(member.path)
        blockdev.lvm.vgreduce(self.name, member.path)

        for (lv, status) in zip(self.lvs, status):
            if lv.status and not status:
                lv.teardown()

    def _add(self, member):
        blockdev.lvm.vgextend(self.name, member.path)

    def _addLogVol(self, lv):
        """ Add an LV to this VG. """
        if lv in self._lvs:
            raise ValueError("lv is already part of this vg")

        # verify we have the space, then add it
        # do not verify for growing vg (because of ks)
        # FIXME: add a "isthin" property and/or "ispool"?
        if not lv.exists and not self.growable and \
           not isinstance(lv, LVMThinLogicalVolumeDevice) and \
           lv.size > self.freeSpace:
            raise errors.DeviceError("new lv is too large to fit in free space", self.name)

        log.debug("Adding %s/%s to %s", lv.name, lv.size, self.name)
        self._lvs.append(lv)

        # snapshot accounting
        origin = getattr(lv, "origin", None)
        if origin:
            origin.snapshots.append(lv)

    def _removeLogVol(self, lv):
        """ Remove an LV from this VG. """
        if lv not in self.lvs:
            raise ValueError("specified lv is not part of this vg")

        self._lvs.remove(lv)

        # snapshot accounting
        origin = getattr(lv, "origin", None)
        if origin:
            origin.snapshots.remove(lv)

    def _addParent(self, member):
        super(LVMVolumeGroupDevice, self)._addParent(member)

        if (self.exists and member.format.exists and
            len(self.parents) + 1 == self.pvCount):
            self._complete = True

    def _removeParent(self, member):
        # XXX It would be nice to raise an exception if removing this member
        #     would not leave enough space, but the devicefactory relies on it
        #     being possible to _temporarily_ overcommit the VG.
        #
        #     Maybe removeMember could be a wrapper with the checks and the
        #     devicefactory could call the _ versions to bypass the checks.
        super(LVMVolumeGroupDevice, self)._removeParent(member)

    # We can't rely on lvm to tell us about our size, free space, &c
    # since we could have modifications queued, unless the VG and all of
    # its PVs already exist.
    #
    #        -- liblvm may contain support for in-memory devices

    @property
    def isModified(self):
        """ Return True if the VG has changes queued that LVM is unaware of. """
        modified = True
        if self.exists and not [d for d in self.pvs if not d.exists]:
            modified = False

        return modified

    @property
    def reservedSpace(self):
        """ Reserved space in this VG """
        reserved = Size(0)
        if self.reserved_percent > 0:
            reserved = self.reserved_percent * Decimal('0.01') * self.size
        elif self.reserved_space > Size(0):
            reserved = self.reserved_space

        return self.align(reserved, roundup=True)

    @property
    def size(self):
        """ The size of this VG """
        # TODO: just ask lvm if isModified returns False

        # sum up the sizes of the PVs and align to pesize
        return sum((max(Size(0), self.align(pv.size - pv.format.peStart)) for pv in self.pvs), Size(0))

    @property
    def extents(self):
        """ Number of extents in this VG """
        # TODO: just ask lvm if isModified returns False

        return int(self.size / self.peSize)

    @property
    def freeSpace(self):
        """ The amount of free space in this VG. """
        # TODO: just ask lvm if isModified returns False

        # get the number of disks used by PVs on RAID (if any)
        raid_disks = 0
        for pv in self.pvs:
            if isinstance(pv, MDRaidArrayDevice):
                raid_disks = max([raid_disks, len(pv.disks)])

        # total the sizes of any LVs
        log.debug("%s size is %s", self.name, self.size)
        used = sum((lv.vgSpaceUsed for lv in self.lvs), Size(0))
        if not self.exists and raid_disks:
            # (only) we allocate (5 * num_disks) extra extents for LV metadata
            # on RAID (see the devicefactory.LVMFactory._get_total_space method)
            new_lvs = [lv for lv in self.lvs if not lv.exists]
            used += len(new_lvs) * 5 * raid_disks * self.peSize
        used += self.reservedSpace
        free = self.size - used
        log.debug("vg %s has %s free", self.name, free)
        return free

    @property
    def freeExtents(self):
        """ The number of free extents in this VG. """
        # TODO: just ask lvm if isModified returns False
        return int(self.freeSpace / self.peSize)

    def align(self, size, roundup=False):
        """ Align a size to a multiple of physical extent size. """
        size = util.numeric_type(size)
        return size.roundToNearest(self.peSize, rounding=ROUND_UP if roundup else ROUND_DOWN)

    @property
    def pvs(self):
        """ A list of this VG's PVs """
        return self.parents[:]

    @property
    def lvs(self):
        """ A list of this VG's LVs """
        return self._lvs[:]

    @property
    def thinpools(self):
        return [l for l in self._lvs if isinstance(l, LVMThinPoolDevice)]

    @property
    def thinlvs(self):
        return [l for l in self._lvs if isinstance(l, LVMThinLogicalVolumeDevice)]

    @property
    def complete(self):
        """Check if the vg has all its pvs in the system
        Return True if complete.
        """
        # vgs with duplicate names are overcomplete, which is not what we want
        if self.hasDuplicate:
            return False

        return self._complete or not self.exists

    @property
    def direct(self):
        """ Is this device directly accessible? """
        return False

    def populateKSData(self, data):
        super(LVMVolumeGroupDevice, self).populateKSData(data)
        data.vgname = self.name
        data.physvols = ["pv.%d" % p.id for p in self.parents]
        data.preexist = self.exists
        if not self.exists:
            data.pesize = self.peSize.convertTo(KiB)

        # reserved percent/space

    @classmethod
    def isNameValid(cls, name):
        # No . or ..
        if name == '.' or name == '..':
            return False

        # Check that all characters are in the allowed set and that the name
        # does not start with a -
        if not re.match('^[a-zA-Z0-9+_.][a-zA-Z0-9+_.-]*$', name):
            return False

        # According to the LVM developers, vgname + lvname is limited to 126 characters
        # minus the number of hyphens, and possibly minus up to another 8 characters
        # in some unspecified set of situations. Instead of figuring all of that out,
        # no one gets a vg or lv name longer than, let's say, 55.
        if len(name) > 55:
            return False

        return True

class LVMLogicalVolumeDevice(DMDevice):
    """ An LVM Logical Volume """
    _type = "lvmlv"
    _resizable = True
    _packages = ["lvm2"]
    _containerClass = LVMVolumeGroupDevice
    _external_dependencies = [availability.BLOCKDEV_LVM_PLUGIN]

    def __init__(self, name, parents=None, size=None, uuid=None, segType=None,
                 fmt=None, exists=False, sysfsPath='', grow=None, maxsize=None,
                 percent=None):
        """
            :param name: the device name (generally a device node's basename)
            :type name: str
            :keyword exists: does this device exist?
            :type exists: bool
            :keyword size: the device's size
            :type size: :class:`~.size.Size`
            :keyword parents: a list of parent devices
            :type parents: list of :class:`StorageDevice`
            :keyword fmt: this device's formatting
            :type fmt: :class:`~.formats.DeviceFormat` or a subclass of it
            :keyword sysfsPath: sysfs device path
            :type sysfsPath: str
            :keyword uuid: the device UUID
            :type uuid: str

            For existing LVs only:

            :keyword copies: number of copies in the vg (>1 for mirrored lvs)
            :type copies: int
            :keyword logSize: size of log volume (for mirrored lvs)
            :type logSize: :class:`~.size.Size`
            :keyword segType: segment type (eg: "linear", "raid1")
            :type segType: str

            For non-existent LVs only:

            :keyword grow: whether to grow this LV
            :type grow: bool
            :keyword maxsize: maximum size for growable LV
            :type maxsize: :class:`~.size.Size`
            :keyword percent -- percent of VG space to take
            :type percent: int

        """

        DMDevice.__init__(self, name, size=size, fmt=fmt,
                          sysfsPath=sysfsPath, parents=parents,
                          exists=exists)

        self.uuid = uuid
        self.segType = segType or "linear"
        self.snapshots = []

        self.req_grow = None
        self.req_max_size = Size(0)
        self.req_size = Size(0)
        self.req_percent = 0

        if not self.exists:
            self.req_grow = grow
            self.req_max_size = Size(util.numeric_type(maxsize))
            # XXX should we enforce that req_size be pe-aligned?
            self.req_size = self._size
            self.req_percent = util.numeric_type(percent)

        # check that we got parents as expected and add this device to them
        self._check_parents()
        self._add_to_parents()

        self._metaDataSize = Size(0)
        self._internal_lvs = []

    def _check_parents(self):
        """Check that this device has parents as expected"""

        if isinstance(self.parents, (list, ParentList)):
            if len(self.parents) != 1:
                raise ValueError("constructor requires a single %s instance" % self._containerClass.__name__)

            container = self.parents[0]
        else:
            container = self.parents

        if not isinstance(container, self._containerClass):
            raise ValueError("constructor requires a %s instance" % self._containerClass.__name__)

    def _add_to_parents(self):
        """Add this device to its parents"""

        # a normal LV has only exactly parent -- the VG it belongs to
        self._parents[0]._addLogVol(self)

    @property
    def copies(self):
        image_lvs = [int_lv for int_lv in self._internal_lvs if isinstance(int_lv, LVMImageLogicalVolumeDevice)]
        return len(image_lvs) or 1

    @property
    def logSize(self):
        log_lvs = (int_lv for int_lv in self._internal_lvs if isinstance(int_lv, LVMLogLogicalVolumeDevice))
        return sum(lv.size for lv in log_lvs)

    @property
    def metaDataSize(self):
        if self._metaDataSize:
            return self._metaDataSize

        md_lvs = (int_lv for int_lv in self._internal_lvs if isinstance(int_lv, LVMMetadataLogicalVolumeDevice))
        return sum(lv.size for lv in md_lvs)

    def __repr__(self):
        s = DMDevice.__repr__(self)
        s += ("  VG device = %(vgdev)r\n"
              "  segment type = %(type)s percent = %(percent)s\n"
              "  mirror copies = %(copies)d"
              "  VG space used = %(vgspace)s" %
              {"vgdev": self.vg, "percent": self.req_percent,
               "copies": self.copies, "type": self.segType,
               "vgspace": self.vgSpaceUsed })
        return s

    @property
    def dict(self):
        d = super(LVMLogicalVolumeDevice, self).dict
        if self.exists:
            d.update({"copies": self.copies,
                      "vgspace": self.vgSpaceUsed})
        else:
            d.update({"percent": self.req_percent})

        return d

    @property
    def mirrored(self):
        return self.copies > 1

    def _setSize(self, size):
        if not isinstance(size, Size):
            raise ValueError("new size must of type Size")

        size = self.vg.align(size)
        log.debug("trying to set lv %s size to %s", self.name, size)
        if size <= self.vg.freeSpace + self.vgSpaceUsed:
            self._size = size
            self.targetSize = size
        else:
            log.debug("failed to set size: %s short", size - (self.vg.freeSpace + self.vgSpaceUsed))
            raise ValueError("not enough free space in volume group")

    size = property(StorageDevice._getSize, _setSize)

    @property
    def maxSize(self):
        """ The maximum size this lv can be. """
        max_lv = self.size + self.vg.freeSpace
        max_format = self.format.maxSize
        return min(max_lv, max_format) if max_format else max_lv

    @property
    def vgSpaceUsed(self):
        """ Space occupied by this LV, not including snapshots. """
        return (self.vg.align(self.size, roundup=True) * self.copies
                + self.logSize + self.metaDataSize)

    @property
    def vg(self):
        """ This Logical Volume's Volume Group. """
        return self.parents[0]

    @property
    def container(self):
        return self.vg

    @property
    def mapName(self):
        """ This device's device-mapper map name """
        # Thank you lvm for this lovely hack.
        return "%s-%s" % (self.vg.mapName, self._name.replace("-","--"))

    @property
    def path(self):
        """ Device node representing this device. """
        return "%s/%s" % (self._devDir, self.mapName)

    def getDMNode(self):
        """ Return the dm-X (eg: dm-0) device node for this device. """
        log_method_call(self, self.name, status=self.status)
        if not self.exists:
            raise errors.DeviceError("device has not been created", self.name)

        return blockdev.dm.node_from_name(self.mapName)

    def _getName(self):
        """ This device's name. """
        return "%s-%s" % (self.vg.name, self._name)

    @property
    def lvname(self):
        """ The LV's name (not including VG name). """
        return self._name

    @property
    def complete(self):
        """ Test if vg exits and if it has all pvs. """
        return self.vg.complete

    def setupParents(self, orig=False):
        # parent is a vg, which has no formatting (or device for that matter)
        Device.setupParents(self, orig=orig)

    def _setup(self, orig=False):
        """ Open, or set up, a device. """
        log_method_call(self, self.name, orig=orig, status=self.status,
                        controllable=self.controllable)
        blockdev.lvm.lvactivate(self.vg.name, self._name)

    def _teardown(self, recursive=None):
        """ Close, or tear down, a device. """
        log_method_call(self, self.name, status=self.status,
                        controllable=self.controllable)
        blockdev.lvm.lvdeactivate(self.vg.name, self._name)

    def _postTeardown(self, recursive=False):
        try:
            # It's likely that teardown of a VG will fail due to other
            # LVs being active (filesystems mounted, &c), so don't let
            # it bring everything down.
            StorageDevice._postTeardown(self, recursive=recursive)
        except errors.StorageError:
            if recursive:
                log.debug("vg %s teardown failed; continuing", self.vg.name)
            else:
                raise

    def _preCreate(self):
        super(LVMLogicalVolumeDevice, self)._preCreate()

        try:
            vg_info = blockdev.lvm.vginfo(self.vg.name)
        except blockdev.LVMError as lvmerr:
            log.error("Failed to get free space for the %s VG: %s", self.vg.name, lvmerr)
            # nothing more can be done, we don't know the VG's free space
            return

        extent_size = Size(vg_info.extent_size)
        extents_free = vg_info.free_count
        can_use = extent_size * extents_free

        if self.size > can_use:
            msg = ("%s LV's size (%s) exceeds the VG's usable free space (%s),"
                  "shrinking the LV") % (self.name, self.size, can_use)
            log.warning(msg)
            self.size = can_use

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        # should we use --zero for safety's sake?
        blockdev.lvm.lvcreate(self.vg.name, self._name, self.size)

    def _preDestroy(self):
        StorageDevice._preDestroy(self)
        # set up the vg's pvs so lvm can remove the lv
        self.vg.setupParents(orig=True)

    def _destroy(self):
        """ Destroy the device. """
        log_method_call(self, self.name, status=self.status)
        blockdev.lvm.lvremove(self.vg.name, self._name)

    def resize(self):
        log_method_call(self, self.name, status=self.status)

        # Setup VG parents (in case they are dmraid partitions for example)
        self.vg.setupParents(orig=True)

        if self.originalFormat and self.originalFormat.exists:
            self.originalFormat.teardown()
        if self.format and self.format.exists:
            self.format.teardown()

        udev.settle()
        blockdev.lvm.lvresize(self.vg.name, self._name, self.size)

    @property
    def isleaf(self):
        # Thin snapshots do not need to be removed prior to removal of the
        # origin, but the old snapshots do.
        non_thin_snapshots = any(s for s in self.snapshots
                                    if not isinstance(s, LVMThinSnapShotDevice))
        return (super(LVMLogicalVolumeDevice, self).isleaf and
                not non_thin_snapshots)

    @property
    def direct(self):
        """ Is this device directly accessible? """
        # an LV can contain a direct filesystem if it is a leaf device or if
        # its only dependent devices are snapshots
        return super(LVMLogicalVolumeDevice, self).isleaf

    def dracutSetupArgs(self):
        # Note no mapName usage here, this is a lvm cmdline name, which
        # is different (ofcourse)
        return set(["rd.lvm.lv=%s/%s" % (self.vg.name, self._name)])

    def checkSize(self):
        """ Check to make sure the size of the device is allowed by the
            format used.

            Returns:
            0  - ok
            1  - Too large
            -1 - Too small
        """
        if self.format.maxSize and self.size > self.format.maxSize:
            return 1
        elif (self.format.minSize and
              (not self.req_grow and
               self.size < self.format.minSize) or
              (self.req_grow and self.req_max_size and
               self.req_max_size < self.format.minSize)):
            return -1
        return 0

    def removeHook(self, modparent=True):
        if modparent:
            self.vg._removeLogVol(self)

        super(LVMLogicalVolumeDevice, self).removeHook(modparent=modparent)

    def addHook(self, new=True):
        super(LVMLogicalVolumeDevice, self).addHook(new=new)
        if new:
            return

        if self not in self.vg.lvs:
            self.vg._addLogVol(self)

    def populateKSData(self, data):
        super(LVMLogicalVolumeDevice, self).populateKSData(data)
        data.vgname = self.vg.name
        data.name = self.lvname
        data.preexist = self.exists
        data.resize = (self.exists and self.targetSize and
                       self.targetSize != self.currentSize)
        if not self.exists:
            data.grow = self.req_grow
            if self.req_grow:
                data.size = self.req_size.convertTo(MiB)
                data.maxSizeMB = self.req_max_size.convertTo(MiB)
            else:
                data.size = self.size.convertTo(MiB)

            data.percent = self.req_percent
        elif data.resize:
            data.size = self.targetSize.convertTo(MiB)

    @classmethod
    def isNameValid(cls, name):
        # Check that the LV name is valid

        # Start with the checks shared with volume groups
        if not LVMVolumeGroupDevice.isNameValid(name):
            return False

        # And now the ridiculous ones
        # These strings are taken from apply_lvname_restrictions in lib/misc/lvm-string.c
        reserved_prefixes = set(['pvmove', 'snapshot'])
        reserved_substrings = set(['_cdata', '_cmeta', '_mimage', '_mlog', '_pmspare', '_rimage',
                                   '_rmeta', '_tdata', '_tmeta', '_vorigin'])

        for prefix in reserved_prefixes:
            if name.startswith(prefix):
                return False

        for substring in reserved_substrings:
            if substring in name:
                return False

        return True

    def addInternalLV(self, int_lv):
        if int_lv not in self._internal_lvs:
            self._internal_lvs.append(int_lv)

    def removeInternalLV(self, int_lv):
        if int_lv in self._internal_lvs:
            self._internal_lvs.remove(int_lv)
        else:
            msg = "the specified internal LV '%s' doesn't belong to this LV ('%s')" % (int_lv.lv_name,
                                                                                       self.name)
            raise ValueError(msg)

@add_metaclass(abc.ABCMeta)
class LVMInternalLogicalVolumeDevice(LVMLogicalVolumeDevice):
    """Abstract base class for internal LVs

    A common class for all classes representing internal Logical Volumes like
    data and metadata parts of pools, RAID images, etc.

    Internal LVs are only referenced by their "parent" LVs (normal LVs they
    back) as all queries and manipulations with them should be done via their
    parent LVs.

    """

    _type = "lvminternallv"

    # generally changes should be done on the parent LV (exceptions should
    # override these)
    _resizable = False
    _readonly = True

    attr_letters = abc.abstractproperty(doc="letters representing the type of the internal LV in the attrs")
    name_suffix = abc.abstractproperty(doc="pattern matching typical/default suffices for internal LVs of this type")
    takes_extra_space = abc.abstractproperty(doc="whether LVs of this type take space in a VG or are part of their parent LVs")

    @classmethod
    def isNameValid(cls, name):
        # override checks for normal LVs, internal LVs typically have names that
        # are forbidden for normal LVs
        return True

    def __init__(self, name, vg, parent_lv=None, size=None, uuid=None,
                 exists=False, segType=None, sysfsPath=''):
        """
        :param vg: the VG this internal LV belongs to
        :type vg: :class:`LVMVolumeGroupDevice`
        :param parent_lv: the parent LV of this internal LV
        :type parent_lv: :class:`LVMLogicalVolumeDevice`

        See :method:`LVMLogicalVolumeDevice.__init__` for details about the
        rest of the parameters.
        """

        # VG name has to be set for parent class' constructors
        self._vg = vg

        # construct the internal LV just like a normal one just with no parents
        # and some parameters set to values reflecting the fact that this is an
        # internal LV
        super(LVMInternalLogicalVolumeDevice, self).__init__(name, parents=None,
              size=size, uuid=uuid, segType=segType, fmt=None, exists=exists,
              sysfsPath=sysfsPath, grow=None, maxsize=None, percent=None)

        self._parent_lv = parent_lv
        if parent_lv:
            self._parent_lv.addInternalLV(self)

    def _check_parents(self):
        # an internal LV should have no parents
        if self._parents:
            raise ValueError("an internal LV should have no parents")

    def _add_to_parents(self):
        # nothing to do here, an internal LV has no parents (in the DeviceTree's
        # meaning of 'parents')
        pass

    @property
    def vg(self):
        return self._vg

    @vg.setter
    def vg(self, vg):
        self._vgpp = vg

    @property
    def parent_lv(self):
        return self._parent_lv

    @parent_lv.setter
    def parent_lv(self, parent_lv):
        if self._parent_lv:
            self._parent_lv.removeInternalLV(self)
        self._parent_lv = parent_lv
        if self._parent_lv:
            self._parent_lv.addInternalLV(self)

    # internal LVs have no format
    def _setFormat(self, f):
        return

    def _getFormat(self):
        return None

    def _setSize(self, size):
        if not isinstance(size, Size):
            raise ValueError("new size must of type Size")

        if not self.takes_extra_space:
            if size <= self.parent_lv.size:
                self._size = size
            else:
                raise ValueError("Internal LV cannot be bigger than its parent LV")
        else:
            # same rules apply as for any other LV
            super(LVMInternalLogicalVolumeDevice, self)._setSize(size)

    @property
    def maxSize(self):
        # no format, so maximum size is only limitted by either the parent LV or the VG
        if not self.takes_extra_space:
            return self._parent_lv.maxSize()
        else:
            return self.size + self.vg.freeSpace

    # ancestor classes' __repr__ expect originalFormat to be != None and some
    # other things
    def __repr__(self):
        s = "%s:\n" % self.__class__.__name__
        s += ("  name = %s, status = %s exists = %s\n" % (self.lvname, self.status, self.exists))
        s += ("  uuid = %s, size = %s\n" % (self.uuid, self.size))
        s += ("  parent LV = %r\n" % self.parent_lv)
        s += ("  VG device = %(vgdev)r\n"
              "  segment type = %(type)s percent = %(percent)s\n"
              "  mirror copies = %(copies)d"
              "  VG space used = %(vgspace)s" %
              {"vgdev": self.vg, "percent": self.req_percent,
               "copies": self.copies, "type": self.segType,
               "vgspace": self.vgSpaceUsed })
        return s

    # generally changes should be done on the parent LV (exceptions should
    # override these)
    def setup(self, orig=False):
        raise errors.DeviceError("An internal LV cannot be set up separately")

    def teardown(self, recursive=None):
        raise errors.DeviceError("An internal LV cannot be torn down separately")

    def destroy(self):
        raise errors.DeviceError("An internal LV cannot be destroyed separately")

    def resize(self):
        raise errors.DeviceError("An internal LV cannot be resized")

    @property
    def growable(self):
        return False

    @property
    def display_lvname(self):
        """Name of the internal LV as displayed by the lvm utilities"""
        return "[%s]" % self.lvname

    # these two methods are not needed right now, because they are only called
    # when devices are added/removed to/from the DeviceTree, but they may come
    # handy in the future
    def addHook(self, new=True):
        # skip LVMLogicalVolumeDevice in the class hierarchy -- we don't want to
        # add an internal LV to the VG (it's only referenced by the parent LV)
        super(LVMLogicalVolumeDevice, self).addHook(new=new)
        self._parent_lv.addInternalLV(self)

    def removeHook(self, modparent=True):
        if modparent:
            self._parent_lv.removeInternalLV(self)

        # skip LVMLogicalVolumeDevice in the class hierarchy -- we cannot remove
        # an internal LV from the VG (it's only referenced by the parent LV)
        super(LVMLogicalVolumeDevice, self).removeHook(modparent=modparent)

    @property
    def direct(self):
        # internal LVs are not directly accessible
        return False

class LVMDataLogicalVolumeDevice(LVMInternalLogicalVolumeDevice):
    """Internal data LV (used by thin/cache pools)"""

    attr_letters = ["T", "C"]
    name_suffix = r"_[tc]data"
    takes_extra_space = False
_INTERNAL_LV_CLASSES.append(LVMDataLogicalVolumeDevice)

class LVMMetadataLogicalVolumeDevice(LVMInternalLogicalVolumeDevice):
    """Internal metadata LV (used by thin/cache pools, RAIDs, etc.)"""

    # thin pool metadata LVs can be resized directly
    _resizable = True

    attr_letters = ["e"]
    # RAIDs can have multiple (numbered) metadata LVs
    name_suffix = r"_[trc]meta(_[0-9]+)?"
    takes_extra_space = True

    # (only) thin pool metadata LVs can be resized directly
    @property
    def resizable(self):
        if self._parent_lv:
            return isinstance(self._parent_lv, LVMThinPoolDevice)
        else:
            # hard to say at this point, just use the name
            return not re.search(r'_[rc]meta', self.lvname)

    # (only) thin pool metadata LVs can be resized directly
    def resize(self):
        if ((self._parent_lv and not isinstance(self._parent_lv, LVMThinPoolDevice)) or
            re.search(r'_[rc]meta', self.lvname)):
            raise errors.DeviceError("RAID and cache pool metadata LVs cannot be resized directly")

        # skip the generic LVMInternalLogicalVolumeDevice class and call the
        # resize() method of the LVMLogicalVolumeDevice
        super(LVMInternalLogicalVolumeDevice, self).resize()

_INTERNAL_LV_CLASSES.append(LVMMetadataLogicalVolumeDevice)

class LVMLogLogicalVolumeDevice(LVMInternalLogicalVolumeDevice):
    """Internal log LV (used by mirrored LVs)"""

    attr_letters = ["l", "L"]
    name_suffix = "_mlog"
    takes_extra_space = True
_INTERNAL_LV_CLASSES.append(LVMLogLogicalVolumeDevice)

class LVMImageLogicalVolumeDevice(LVMInternalLogicalVolumeDevice):
    """Internal image LV (used by mirror/RAID LVs)"""

    attr_letters = ["i"]
    # RAIDs have multiple (numbered) image LVs
    name_suffix = r"_[rm]image(_[0-9]+)?"
    takes_extra_space = False
_INTERNAL_LV_CLASSES.append(LVMImageLogicalVolumeDevice)

class LVMOriginLogicalVolumeDevice(LVMInternalLogicalVolumeDevice):
    """Internal origin LV (e.g. the raw/uncached part of a cached LV)"""

    attr_letters = ["o"]
    name_suffix = r"_c?orig"
    takes_extra_space = False
_INTERNAL_LV_CLASSES.append(LVMOriginLogicalVolumeDevice)

@add_metaclass(abc.ABCMeta)
class LVMSnapShotBase(object):
    """ Abstract base class for lvm snapshots

        This class is intended to be used with multiple inheritance in addition
        to some subclass of :class:`~.StorageDevice`.

        Snapshots do not have their origin/source volume as parent. They are
        like other LVs except that they have an origin attribute and are in that
        instance's snapshots list.

        Normal/old snapshots must be removed with their origin, while thin
        snapshots can remain after their origin is removed.

        It is also impossible to set the format for a snapshot explicitly as it
        always has the same format as its origin.
    """
    _type = "lvmsnapshotbase"

    def __init__(self, origin=None, vorigin=False, exists=False):
        """
            :keyword :class:`~.LVMLogicalVolumeDevice` origin: source volume
            :keyword bool vorigin: is this a vorigin snapshot?
            :keyword bool exists: is this an existing snapshot?

            vorigin is a special type of device that makes use of snapshots to
            create a sparse device. These snapshots have no origin lv, instead
            using space in the vg directly. Only preexisting vorigin snapshots
            are supported here.
        """
        self._originSpecifiedCheck(origin, vorigin, exists)
        self._originTypeCheck(origin)
        self._originExistenceCheck(origin)
        self._voriginExistenceCheck(vorigin, exists)

        self.origin = origin
        """ the snapshot's source volume """

        self.vorigin = vorigin
        """ a boolean flag indicating a vorigin snapshot """

    def _originSpecifiedCheck(self, origin, vorigin, exists):
        # pylint: disable=unused-argument
        if not origin and not vorigin:
            raise ValueError("lvm snapshot devices require an origin lv")

    def _originTypeCheck(self, origin):
        if origin and not isinstance(origin, LVMLogicalVolumeDevice):
            raise ValueError("lvm snapshot origin must be a logical volume")

    def _originExistenceCheck(self, origin):
        if origin and not origin.exists:
            raise ValueError("lvm snapshot origin volume must already exist")

    def _voriginExistenceCheck(self, vorigin, exists):
        if vorigin and not exists:
            raise ValueError("only existing vorigin snapshots are supported")

    def _setFormat(self, fmt):
        pass

    def _getFormat(self):
        if self.origin is None:
            fmt = getFormat(None)
        else:
            fmt = self.origin.format
        return fmt

    @abc.abstractmethod
    def _create(self):
        """ Create the device. """
        raise NotImplementedError()

    def merge(self):
        """ Merge the snapshot back into its origin volume. """
        log_method_call(self, self.name, status=self.status) # pylint: disable=no-member
        self.vg.setup()    # pylint: disable=no-member
        try:
            self.origin.teardown()
        except errors.FSError:
            # the merge will begin based on conditions described in the --merge
            # section of lvconvert(8)
            pass

        try:
            self.teardown() # pylint: disable=no-member
        except errors.FSError:
            pass

        udev.settle()
        blockdev.lvm.lvsnapshotmerge(self.vg.name, self.lvname) # pylint: disable=no-member


class LVMSnapShotDevice(LVMSnapShotBase, LVMLogicalVolumeDevice):
    """ An LVM snapshot """
    _type = "lvmsnapshot"
    _formatImmutable = True

    def __init__(self, name, parents=None, size=None, uuid=None,
                 copies=1, logSize=None, segType=None,
                 fmt=None, exists=False, sysfsPath='',
                 grow=None, maxsize=None, percent=None,
                 origin=None, vorigin=False):
        """ Create an LVMSnapShotDevice instance.

            This class is for the old-style (not thin) lvm snapshots. The origin
            volume cannot be removed without also removing all snapshots (not so
            for thin snapshots). Also, the snapshot is automatically activated
            or deactivated with its origin.

            :param str name: the device name (generally a device node basename)
            :keyword bool exists: does this device exist?
            :keyword :class:`~.size.Size` size: the device's size
            :keyword :class:`~.ParentList` parents: list of parent devices
            :keyword fmt: this device's formatting
            :type fmt: :class:`~.formats.DeviceFormat`
            :keyword str sysfsPath: sysfs device path
            :keyword str uuid: the device UUID
            :keyword str segType: segment type

            :keyword :class:`~.StorageDevice` origin: the origin/source volume
            :keyword bool vorigin: is this a vorigin snapshot?

            For non-existent devices only:

            :keyword bool grow: whether to grow this LV
            :keyword :class:`~.size.Size` maxsize: maximum size for growable LV
            :keyword int percent: percent of VG space to take
        """
        # pylint: disable=unused-argument

        if isinstance(origin, LVMLogicalVolumeDevice) and \
           isinstance(parents[0], LVMVolumeGroupDevice) and \
           origin.vg != parents[0]:
            raise ValueError("lvm snapshot and origin must be in the same vg")

        LVMSnapShotBase.__init__(self, origin=origin, vorigin=vorigin,
                                 exists=exists)

        LVMLogicalVolumeDevice.__init__(self, name, parents=parents, size=size,
                                        uuid=uuid, fmt=None, exists=exists,
                                        copies=copies, logSize=logSize,
                                        segType=segType,
                                        sysfsPath=sysfsPath, grow=grow,
                                        maxsize=maxsize, percent=percent)

    def setup(self, orig=False):
        pass

    def teardown(self, recursive=False):
        pass

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        blockdev.lvm.lvsnapshotcreate(self.vg.name, self.origin.lvname, self._name, self.size)

    def _destroy(self):
        """ Destroy the device. """
        log_method_call(self, self.name, status=self.status)
        # old-style snapshots' status is tied to the origin's so we never
        # explicitly activate or deactivate them and we have to tell lvremove
        # that it is okay to remove the active snapshot
        blockdev.lvm.lvremove(self.vg.name, self._name, force=True)

    def _getPartedDevicePath(self):
        return "%s-cow" % self.path

    def dependsOn(self, dep):
        # pylint: disable=bad-super-call
        return (self.origin == dep or
                super(LVMSnapShotBase, self).dependsOn(dep))

    def readCurrentSize(self):
        log_method_call(self, exists=self.exists, path=self.path,
                        sysfsPath=self.sysfsPath)
        size = Size(0)
        if self.exists and os.path.isdir(self.sysfsPath):
            cowSysfsPath = util.get_cow_sysfs_path(self.path, self.sysfsPath)

            if os.path.exists(cowSysfsPath) and os.path.isdir(cowSysfsPath):
                blocks = int(util.get_sysfs_attr(cowSysfsPath, "size"))
                size = Size(blocks * LINUX_SECTOR_SIZE)

        return size

class LVMThinPoolDevice(LVMLogicalVolumeDevice):
    """ An LVM Thin Pool """
    _type = "lvmthinpool"
    _resizable = False

    def __init__(self, name, parents=None, size=None, uuid=None,
                 fmt=None, exists=False, sysfsPath='',
                 grow=None, maxsize=None, percent=None,
                 metadatasize=None, chunksize=None, segType=None, profile=None):
        """
            :param name: the device name (generally a device node's basename)
            :type name: str
            :keyword exists: does this device exist?
            :type exists: bool
            :keyword size: the device's size
            :type size: :class:`~.size.Size`
            :keyword parents: a list of parent devices
            :type parents: list of :class:`StorageDevice`
            :keyword fmt: this device's formatting
            :type fmt: :class:`~.formats.DeviceFormat` or a subclass of it
            :keyword sysfsPath: sysfs device path
            :type sysfsPath: str
            :keyword uuid: the device UUID
            :type uuid: str
            :keyword segType: segment type
            :type segType: str

            For non-existent pools only:

            :keyword grow: whether to grow this LV
            :type grow: bool
            :keyword maxsize: maximum size for growable LV
            :type maxsize: :class:`~.size.Size`
            :keyword percent: percent of VG space to take
            :type percent: int
            :keyword metadatasize: the size of the metadata LV
            :type metadatasize: :class:`~.size.Size`
            :keyword chunksize: chunk size for the pool
            :type chunksize: :class:`~.size.Size`
            :keyword profile: (allocation) profile for the pool or None (unspecified)
            :type profile: :class:`~.devicelibs.lvm.ThPoolProfile` or NoneType

        """
        if metadatasize is not None and \
           not blockdev.lvm.is_valid_thpool_md_size(metadatasize):
            raise ValueError("invalid metadatasize value")

        if chunksize is not None and \
           not blockdev.lvm.is_valid_thpool_chunk_size(chunksize):
            raise ValueError("invalid chunksize value")

        super(LVMThinPoolDevice, self).__init__(name, parents=parents,
                                                size=size, uuid=uuid,
                                                fmt=fmt, exists=exists,
                                                sysfsPath=sysfsPath, grow=grow,
                                                maxsize=maxsize,
                                                percent=percent,
                                                segType=segType)

        self._metaDataSize = metadatasize or Size(0)
        self.chunkSize = chunksize or Size(0)
        self.profile = profile
        self._lvs = []

    def _addLogVol(self, lv):
        """ Add an LV to this pool. """
        if lv in self._lvs:
            raise ValueError("lv is already part of this vg")

        # TODO: add some checking to prevent overcommit for preexisting
        self.vg._addLogVol(lv)
        log.debug("Adding %s/%s to %s", lv.name, lv.size, self.name)
        self._lvs.append(lv)

    def _removeLogVol(self, lv):
        """ Remove an LV from this pool. """
        if lv not in self._lvs:
            raise ValueError("specified lv is not part of this vg")

        self._lvs.remove(lv)
        self.vg._removeLogVol(lv)

    @property
    def lvs(self):
        """ A list of this pool's LVs """
        return self._lvs[:]     # we don't want folks changing our list

    @property
    def vgSpaceUsed(self):
        space = super(LVMThinPoolDevice, self).vgSpaceUsed
        space += Size(blockdev.lvm.get_thpool_padding(space, self.vg.peSize))
        return space

    @property
    def usedSpace(self):
        return sum((l.poolSpaceUsed for l in self.lvs), Size(0))

    @property
    def freeSpace(self):
        return self.size - self.usedSpace

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        if self.profile:
            profile_name = self.profile.name
        else:
            profile_name = None
        # TODO: chunk size, data/metadata split --> profile
        blockdev.lvm.thpoolcreate(self.vg.name, self.lvname, self.size,
                                  md_size=self.metaDataSize,
                                  chunk_size=self.chunkSize,
                                  profile=profile_name)

    def dracutSetupArgs(self):
        return set()

    @property
    def direct(self):
        """ Is this device directly accessible? """
        return False

    def populateKSData(self, data):
        super(LVMThinPoolDevice, self).populateKSData(data)
        data.mountpoint = "none"
        data.thin_pool = True
        data.metadata_size = self.metaDataSize.convertTo(MiB)
        data.chunk_size = self.chunkSize.convertTo(KiB)
        if self.profile:
            data.profile = self.profile.name

class LVMThinLogicalVolumeDevice(LVMLogicalVolumeDevice):
    """ An LVM Thin Logical Volume """
    _type = "lvmthinlv"
    _containerClass = LVMThinPoolDevice

    @property
    def pool(self):
        return self.parents[0]

    @property
    def vg(self):
        return self.pool.vg

    @property
    def poolSpaceUsed(self):
        """ The total space used within the thin pool by this volume.

            This should probably align to the greater of vg extent size and
            pool chunk size. If it ends up causing overcommit in the amount of
            less than one chunk per thin lv, so be it.
        """
        return self.vg.align(self.size, roundup=True)

    @property
    def vgSpaceUsed(self):
        return Size(0)    # the pool's size is already accounted for in the vg

    def _setSize(self, size):
        if not isinstance(size, Size):
            raise ValueError("new size must of type Size")

        size = self.vg.align(size)
        size = self.vg.align(util.numeric_type(size))
        self._size = size
        self.targetSize = size

    size = property(StorageDevice._getSize, _setSize)

    def _preCreate(self):
        # skip LVMLogicalVolumeDevice's _preCreate() method as it checks for a
        # free space in a VG which doesn't make sense for a ThinLV and causes a
        # bug by limitting the ThinLV's size to VG free space which is nonsense
        super(LVMLogicalVolumeDevice, self)._preCreate() # pylint: disable=bad-super-call

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        blockdev.lvm.thlvcreate(self.vg.name, self.pool.lvname, self.lvname,
                                self.size)

    def removeHook(self, modparent=True):
        if modparent:
            self.pool._removeLogVol(self)

        # pylint: disable=bad-super-call
        super(LVMLogicalVolumeDevice, self).removeHook(modparent=modparent)

    def addHook(self, new=True):
        # pylint: disable=bad-super-call
        super(LVMLogicalVolumeDevice, self).addHook(new=new)
        if new:
            return

        if self not in self.pool.lvs:
            self.pool._addLogVol(self)

    def populateKSData(self, data):
        super(LVMThinLogicalVolumeDevice, self).populateKSData(data)
        data.thin_volume = True
        data.pool_name = self.pool.lvname

class LVMThinSnapShotDevice(LVMSnapShotBase, LVMThinLogicalVolumeDevice):
    """ An LVM Thin Snapshot """
    _type = "lvmthinsnapshot"
    _resizable = False
    _formatImmutable = True

    def __init__(self, name, parents=None, sysfsPath='', origin=None,
                 fmt=None, uuid=None, size=None, exists=False, segType=None):
        """
            :param str name: the name of the device
            :param :class:`~.ParentList` parents: parent devices
            :param str sysfsPath: path to this device's /sys directory
            :keyword origin: the origin(source) volume for the snapshot
            :type origin: :class:`~.LVMLogicalVolumeDevice` or None
            :keyword str segType: segment type
            :keyword :class:`~.formats.DeviceFormat` fmt: this device's format
            :keyword str uuid: the device UUID
            :keyword :class:`~.size.Size` size: the device's size
            :keyword bool exists: is this an existing device?

            LVM thin snapshots can remain after their origin volume is removed,
            unlike the older-style snapshots.
        """
        # pylint: disable=unused-argument

        if isinstance(origin, LVMLogicalVolumeDevice) and \
           isinstance(parents[0], LVMThinPoolDevice) and \
           origin.vg != parents[0].vg:
            raise ValueError("lvm snapshot and origin must be in the same vg")

        if size and not exists:
            raise ValueError("thin snapshot size is determined automatically")

        LVMSnapShotBase.__init__(self, origin=origin, exists=exists)
        LVMThinLogicalVolumeDevice.__init__(self, name, parents=parents,
                                            sysfsPath=sysfsPath,fmt=None,
                                            segType=segType,
                                            uuid=uuid, size=size, exists=exists)

    def _originSpecifiedCheck(self, origin, vorigin, exists):
        if not exists and not origin:
            raise ValueError("non-existent lvm thin snapshots require an origin")

    def _setup(self, orig=False):
        """ Open, or set up, a device. """
        log_method_call(self, self.name, orig=orig, status=self.status,
                        controllable=self.controllable)
        blockdev.lvm.lvactivate(self.vg.name, self._name, ignore_skip=True)

    def _create(self):
        """ Create the device. """
        log_method_call(self, self.name, status=self.status)
        pool_name = None
        if not isinstance(self.origin, LVMThinLogicalVolumeDevice):
            # if the origin is not a thin volume we need to tell lvm which pool
            # to use
            pool_name = self.pool.lvname

        blockdev.lvm.thsnapshotcreate(self.vg.name, self._name, self.origin.lvname,
                                      pool_name=pool_name)

    def dependsOn(self, dep):
        # once a thin snapshot exists it no longer depends on its origin
        return ((self.origin == dep and not self.exists) or
                super(LVMThinSnapShotDevice, self).dependsOn(dep))