Use attribute metadata to drive maintenance of backlinks
By backlinks I mean for example the link a filesystem has to a mount that uses it, or the link from a partition to the RAID it is a member of. This might be a little magical, but something like this is really nice when interpreting config objects from curtin.
This commit is contained in:
Michael Hudson-Doyle
parent
67884836db
commit
18374cef06
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@ -27,7 +27,48 @@ import platform
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log = logging.getLogger('subiquity.models.filesystem')
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def _set_backlinks(obj):
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for field in attr.fields(type(obj)):
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backlink = field.metadata.get('backlink')
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if backlink is None:
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continue
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v = getattr(obj, field.name)
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if v is None:
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continue
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if not isinstance(v, (list, set)):
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v = [v]
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for vv in v:
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b = getattr(vv, backlink, None)
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if isinstance(b, list):
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b.append(obj)
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elif isinstance(b, set):
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b.add(obj)
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else:
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setattr(vv, backlink, obj)
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def _remove_backlinks(obj):
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for field in attr.fields(type(obj)):
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backlink = field.metadata.get('backlink')
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if backlink is None:
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continue
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v = getattr(obj, field.name)
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if v is None:
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continue
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if not isinstance(v, (list, set)):
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v = [v]
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for vv in v:
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b = getattr(vv, backlink, None)
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if isinstance(b, list):
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b.remove(obj)
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elif isinstance(b, set):
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b.remove(obj)
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else:
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setattr(vv, backlink, None)
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def fsobj(c):
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c.__attrs_post_init__ = _set_backlinks
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return attr.s(cmp=False)(c)
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@ -161,12 +202,18 @@ def idfield(base):
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return attr.ib(default=attr.Factory(factory))
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def ref():
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return attr.ib(default=None, metadata={'ref': True})
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def ref(*, backlink=None):
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metadata = {'ref': True}
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if backlink:
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metadata['backlink'] = backlink
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return attr.ib(default=None, metadata=metadata)
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def reflist():
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return attr.ib(default=attr.Factory(set), metadata={'reflist': True})
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def reflist(*, backlink=None):
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metadata = {'reflist': True}
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if backlink:
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metadata['backlink'] = backlink
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return attr.ib(default=attr.Factory(set), metadata=metadata)
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def const(value):
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@ -478,7 +525,7 @@ class Partition(_Formattable):
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id = idfield("part")
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type = const("partition")
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device = ref() # Disk
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device = ref(backlink="_partitions") # Disk
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size = attr.ib(default=None)
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wipe = attr.ib(default=None)
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flag = attr.ib(default=None)
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@ -543,8 +590,8 @@ class Raid(_Device):
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preserve = attr.ib(default=False)
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name = attr.ib(default=None)
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raidlevel = attr.ib(default=None) # 0, 1, 5, 6, 10
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devices = reflist() # set([_Formattable])
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spare_devices = reflist() # set([_Formattable])
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devices = reflist(backlink="_constructed_device") # set([_Formattable])
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spare_devices = reflist(backlink="_constructed_device") # ditto
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ptable = attr.ib(default=None)
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@property
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@ -623,7 +670,7 @@ class LVM_VolGroup(_Device):
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type = const("lvm_volgroup")
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preserve = attr.ib(default=False)
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name = attr.ib(default=None)
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devices = reflist() # set([_Formattable])
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devices = reflist(backlink="_constructed_device") # set([_Formattable])
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_passphrase = attr.ib(default=None, repr=False)
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def serialize_devices(self):
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@ -691,7 +738,7 @@ class LVM_LogicalVolume(_Formattable):
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id = idfield("lv")
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type = const("lvm_partition")
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name = attr.ib(default=None)
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volgroup = ref() # LVM_VolGroup
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volgroup = ref(backlink="_partitions") # LVM_VolGroup
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size = attr.ib(default=None)
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preserve = attr.ib(default=False)
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@ -744,7 +791,7 @@ class Filesystem:
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id = idfield("fs")
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type = const("format")
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fstype = attr.ib(default=None)
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volume = ref() # _Formattable
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volume = ref(backlink="_fs") # _Formattable
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label = attr.ib(default=None)
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uuid = attr.ib(default=None)
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preserve = attr.ib(default=False)
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@ -767,7 +814,7 @@ class Filesystem:
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class Mount:
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id = idfield("mount")
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type = const("mount")
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device = ref() # Filesystem
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device = ref(backlink="_mount") # Filesystem
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path = attr.ib(default=None)
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def can_delete(self):
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@ -983,9 +1030,7 @@ class FilesystemModel(object):
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raise Exception("%s is already formatted" % (disk.label,))
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p = Partition(device=disk, size=real_size, flag=flag, wipe=wipe)
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if flag in ("boot", "bios_grub", "prep"):
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disk._partitions.insert(0, p)
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else:
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disk._partitions.append(p)
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disk._partitions.insert(0, disk._partitions.pop())
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disk.ptable = 'gpt'
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self._partitions.append(p)
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return p
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@ -993,7 +1038,7 @@ class FilesystemModel(object):
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def remove_partition(self, part):
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if part._fs or part._constructed_device:
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raise Exception("can only remove empty partition")
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part.device._partitions.remove(part)
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_remove_backlinks(part)
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self._partitions.remove(part)
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if len(part.device._partitions) == 0:
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part.device.ptable = None
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@ -1007,43 +1052,35 @@ class FilesystemModel(object):
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for d in devices | spare_devices:
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if isinstance(d, Disk):
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self._use_disk(d)
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d._constructed_device = r
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self._raids.append(r)
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return r
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def remove_raid(self, raid):
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if raid._fs or raid._constructed_device or len(raid.partitions()):
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raise Exception("can only remove empty RAID")
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for d in raid.devices:
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d._constructed_device = None
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_remove_backlinks(raid)
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self._raids.remove(raid)
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def add_volgroup(self, name, devices, passphrase):
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vg = LVM_VolGroup(name=name, devices=devices, passphrase=passphrase)
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for d in devices:
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if isinstance(d, Disk):
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self._use_disk(d)
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d._constructed_device = vg
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self._vgs.append(vg)
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return vg
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def remove_volgroup(self, vg):
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if len(vg._partitions):
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raise Exception("can only remove empty VG")
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for d in vg.devices:
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d._constructed_device = None
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_remove_backlinks(vg)
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self._vgs.remove(vg)
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def add_logical_volume(self, vg, name, size):
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lv = LVM_LogicalVolume(volgroup=vg, name=name, size=size)
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vg._partitions.append(lv)
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self._lvs.append(lv)
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return lv
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def remove_logical_volume(self, lv):
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if lv._fs:
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raise Exception("can only remove empty LV")
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lv.volgroup._partitions.remove(lv)
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_remove_backlinks(lv)
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self._lvs.remove(lv)
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def add_filesystem(self, volume, fstype):
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@ -1057,25 +1094,25 @@ class FilesystemModel(object):
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self._use_disk(volume)
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if volume._fs is not None:
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raise Exception("%s is already formatted")
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volume._fs = fs = Filesystem(volume=volume, fstype=fstype)
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fs = Filesystem(volume=volume, fstype=fstype)
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self._filesystems.append(fs)
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return fs
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def remove_filesystem(self, fs):
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if fs._mount:
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raise Exception("can only remove unmounted filesystem")
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fs.volume._fs = None
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_remove_backlinks(fs)
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self._filesystems.remove(fs)
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def add_mount(self, fs, path):
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if fs._mount is not None:
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raise Exception("%s is already mounted")
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fs._mount = m = Mount(device=fs, path=path)
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m = Mount(device=fs, path=path)
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self._mounts.append(m)
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return m
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def remove_mount(self, mount):
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mount.device._mount = None
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_remove_backlinks(mount)
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self._mounts.remove(mount)
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def any_configuration_done(self):
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