root / lib / storage.py @ 58d38b02
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# Copyright (C) 2009 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Storage container abstraction.
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"""
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import logging |
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from ganeti import errors |
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from ganeti import constants |
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from ganeti import utils |
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def _ParseSize(value): |
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return int(round(float(value), 0)) |
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class _Base: |
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"""Base class for storage abstraction.
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"""
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def List(self, name, fields): |
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"""Returns a list of all entities within the storage unit.
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@type name: string or None
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@param name: Entity name or None for all
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@type fields: list
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@param fields: List with all requested result fields (order is preserved)
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"""
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raise NotImplementedError() |
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def Modify(self, name, changes): |
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"""Modifies an entity within the storage unit.
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@type name: string
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@param name: Entity name
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@type changes: dict
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@param changes: New field values
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"""
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# Don't raise an error if no changes are requested
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if changes:
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raise errors.ProgrammerError("Unable to modify the following" |
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"fields: %r" % (changes.keys(), ))
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def Execute(self, name, op): |
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"""Executes an operation on an entity within the storage unit.
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@type name: string
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@param name: Entity name
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@type op: string
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@param op: Operation name
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"""
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raise NotImplementedError() |
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class FileStorage(_Base): |
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"""File storage unit.
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"""
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def __init__(self, paths): |
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"""Initializes this class.
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@type paths: list
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@param paths: List of file storage paths
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"""
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self._paths = paths
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def List(self, name, fields): |
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"""Returns a list of all entities within the storage unit.
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See L{_Base.List}.
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"""
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rows = [] |
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if name is None: |
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paths = self._paths
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else:
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paths = [name] |
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for path in paths: |
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rows.append(self._ListInner(path, fields))
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return rows
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@staticmethod
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def _ListInner(path, fields): |
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"""Gathers requested information from directory.
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@type path: string
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@param path: Path to directory
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@type fields: list
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@param fields: Requested fields
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"""
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values = [] |
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# Pre-calculate information in case it's requested more than once
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if constants.SF_USED in fields: |
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dirsize = utils.CalculateDirectorySize(path) |
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else:
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dirsize = None
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if constants.SF_FREE in fields or constants.SF_SIZE in fields: |
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fsstats = utils.GetFilesystemStats(path) |
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else:
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fsstats = None
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# Make sure to update constants.VALID_STORAGE_FIELDS when changing fields.
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for field_name in fields: |
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if field_name == constants.SF_NAME:
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values.append(path) |
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elif field_name == constants.SF_USED:
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values.append(dirsize) |
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elif field_name == constants.SF_FREE:
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values.append(fsstats[1])
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elif field_name == constants.SF_SIZE:
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values.append(fsstats[0])
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elif field_name == constants.SF_ALLOCATABLE:
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values.append(True)
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else:
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raise errors.StorageError("Unknown field: %r" % field_name) |
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return values
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class _LvmBase(_Base): |
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"""Base class for LVM storage containers.
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@cvar LIST_FIELDS: list of tuples consisting of three elements: SF_*
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constants, lvm command output fields (list), and conversion
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function or static value (for static value, the lvm output field
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can be an empty list)
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"""
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LIST_SEP = "|"
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LIST_COMMAND = None
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LIST_FIELDS = None
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def List(self, name, wanted_field_names): |
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"""Returns a list of all entities within the storage unit.
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See L{_Base.List}.
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"""
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# Get needed LVM fields
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lvm_fields = self._GetLvmFields(self.LIST_FIELDS, wanted_field_names) |
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# Build LVM command
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cmd_args = self._BuildListCommand(self.LIST_COMMAND, self.LIST_SEP, |
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lvm_fields, name) |
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# Run LVM command
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cmd_result = self._RunListCommand(cmd_args)
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# Split and rearrange LVM command output
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return self._BuildList(self._SplitList(cmd_result, self.LIST_SEP, |
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len(lvm_fields)),
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self.LIST_FIELDS,
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wanted_field_names, |
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lvm_fields) |
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@staticmethod
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def _GetLvmFields(fields_def, wanted_field_names): |
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"""Returns unique list of fields wanted from LVM command.
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@type fields_def: list
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@param fields_def: Field definitions
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@type wanted_field_names: list
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@param wanted_field_names: List of requested fields
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"""
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field_to_idx = dict([(field_name, idx)
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for (idx, (field_name, _, _)) in |
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enumerate(fields_def)])
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lvm_fields = [] |
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for field_name in wanted_field_names: |
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try:
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idx = field_to_idx[field_name] |
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except IndexError: |
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raise errors.StorageError("Unknown field: %r" % field_name) |
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(_, lvm_names, _) = fields_def[idx] |
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lvm_fields.extend(lvm_names) |
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return utils.UniqueSequence(lvm_fields)
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@classmethod
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def _BuildList(cls, cmd_result, fields_def, wanted_field_names, lvm_fields): |
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"""Builds the final result list.
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@type cmd_result: iterable
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@param cmd_result: Iterable of LVM command output (iterable of lists)
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@type fields_def: list
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@param fields_def: Field definitions
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@type wanted_field_names: list
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@param wanted_field_names: List of requested fields
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@type lvm_fields: list
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@param lvm_fields: LVM fields
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"""
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lvm_name_to_idx = dict([(lvm_name, idx)
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for (idx, lvm_name) in enumerate(lvm_fields)]) |
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field_to_idx = dict([(field_name, idx)
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for (idx, (field_name, _, _)) in |
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enumerate(fields_def)])
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data = [] |
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for raw_data in cmd_result: |
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row = [] |
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for field_name in wanted_field_names: |
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(_, lvm_names, mapper) = fields_def[field_to_idx[field_name]] |
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values = [raw_data[lvm_name_to_idx[i]] for i in lvm_names] |
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if callable(mapper): |
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# we got a function, call it with all the declared fields
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val = mapper(*values) |
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elif len(values) == 1: |
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# we don't have a function, but we had a single field
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# declared, pass it unchanged
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val = values[0]
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else:
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# let's make sure there are no fields declared (cannot map >
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# 1 field without a function)
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assert not values, "LVM storage has multi-fields without a function" |
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val = mapper |
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row.append(val) |
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data.append(row) |
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return data
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@staticmethod
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def _BuildListCommand(cmd, sep, options, name): |
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"""Builds LVM command line.
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@type cmd: string
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@param cmd: Command name
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@type sep: string
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@param sep: Field separator character
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@type options: list of strings
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@param options: Wanted LVM fields
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@type name: name or None
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@param name: Name of requested entity
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"""
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args = [cmd, |
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"--noheadings", "--units=m", "--nosuffix", |
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"--separator", sep,
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"--options", ",".join(options)] |
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if name is not None: |
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args.append(name) |
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return args
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@staticmethod
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def _RunListCommand(args): |
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"""Run LVM command.
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"""
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result = utils.RunCmd(args) |
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if result.failed:
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raise errors.StorageError("Failed to run %r, command output: %s" % |
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(args[0], result.output))
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return result.stdout
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@staticmethod
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def _SplitList(data, sep, fieldcount): |
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"""Splits LVM command output into rows and fields.
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@type data: string
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@param data: LVM command output
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@type sep: string
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@param sep: Field separator character
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@type fieldcount: int
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@param fieldcount: Expected number of fields
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"""
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for line in data.splitlines(): |
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fields = line.strip().split(sep) |
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if len(fields) != fieldcount: |
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logging.warning("Invalid line returned from lvm command: %s", line)
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continue
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yield fields
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class LvmPvStorage(_LvmBase): |
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"""LVM Physical Volume storage unit.
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"""
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def _GetAllocatable(attr): |
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if attr:
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return (attr[0] == "a") |
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else:
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logging.warning("Invalid PV attribute: %r", attr)
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return False |
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LIST_COMMAND = "pvs"
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# Make sure to update constants.VALID_STORAGE_FIELDS when changing field
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# definitions.
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LIST_FIELDS = [ |
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(constants.SF_NAME, ["pv_name"], None), |
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(constants.SF_SIZE, ["pv_size"], _ParseSize),
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(constants.SF_USED, ["pv_used"], _ParseSize),
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(constants.SF_FREE, ["pv_free"], _ParseSize),
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(constants.SF_ALLOCATABLE, ["pv_attr"], _GetAllocatable),
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] |
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def _SetAllocatable(self, name, allocatable): |
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"""Sets the "allocatable" flag on a physical volume.
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@type name: string
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@param name: Physical volume name
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@type allocatable: bool
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@param allocatable: Whether to set the "allocatable" flag
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"""
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args = ["pvchange", "--allocatable"] |
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if allocatable:
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args.append("y")
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else:
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args.append("n")
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args.append(name) |
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result = utils.RunCmd(args) |
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if result.failed:
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raise errors.StorageError("Failed to modify physical volume," |
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" pvchange output: %s" %
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result.output) |
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def Modify(self, name, changes): |
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"""Modifies flags on a physical volume.
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See L{_Base.Modify}.
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"""
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if constants.SF_ALLOCATABLE in changes: |
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self._SetAllocatable(name, changes[constants.SF_ALLOCATABLE])
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del changes[constants.SF_ALLOCATABLE]
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# Other changes will be handled (and maybe refused) by the base class.
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return _LvmBase.Modify(self, name, changes) |
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class LvmVgStorage(_LvmBase): |
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"""LVM Volume Group storage unit.
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"""
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LIST_COMMAND = "vgs"
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# Make sure to update constants.VALID_STORAGE_FIELDS when changing field
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# definitions.
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LIST_FIELDS = [ |
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(constants.SF_NAME, ["vg_name"], None), |
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(constants.SF_SIZE, ["vg_size"], _ParseSize),
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(constants.SF_FREE, ["vg_free"], _ParseSize),
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(constants.SF_USED, ["vg_size", "vg_free"], |
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lambda x, y: _ParseSize(x) - _ParseSize(y)),
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(constants.SF_ALLOCATABLE, [], True),
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] |
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def _RemoveMissing(self, name): |
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"""Runs "vgreduce --removemissing" on a volume group.
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@type name: string
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@param name: Volume group name
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"""
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# Ignoring vgreduce exit code. Older versions exit with an error even tough
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# the VG is already consistent. This was fixed in later versions, but we
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# cannot depend on it.
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result = utils.RunCmd(["vgreduce", "--removemissing", name]) |
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# Keep output in case something went wrong
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vgreduce_output = result.output |
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result = utils.RunCmd(["vgs", "--noheadings", "--nosuffix", name]) |
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if result.failed:
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raise errors.StorageError(("Volume group '%s' still not consistent," |
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" 'vgreduce' output: %r,"
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" 'vgs' output: %r") %
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(name, vgreduce_output, result.output)) |
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def Execute(self, name, op): |
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"""Executes an operation on a virtual volume.
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See L{_Base.Execute}.
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"""
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if op == constants.SO_FIX_CONSISTENCY:
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return self._RemoveMissing(name) |
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return _LvmBase.Execute(self, name, op) |
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# Lookup table for storage types
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_STORAGE_TYPES = { |
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constants.ST_FILE: FileStorage, |
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constants.ST_LVM_PV: LvmPvStorage, |
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constants.ST_LVM_VG: LvmVgStorage, |
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} |
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def GetStorageClass(name): |
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"""Returns the class for a storage type.
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@type name: string
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@param name: Storage type
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"""
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try:
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return _STORAGE_TYPES[name]
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except KeyError: |
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raise errors.StorageError("Unknown storage type: %r" % name) |
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def GetStorage(name, *args): |
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"""Factory function for storage methods.
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@type name: string
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@param name: Storage type
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"""
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return GetStorageClass(name)(*args)
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