188 lines
7.1 KiB
Python
188 lines
7.1 KiB
Python
# Copyright 2017 Andreas Florath (andreas@florath.net)
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import functools
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import logging
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import os
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import time
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from diskimage_builder.block_device.exception \
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import BlockDeviceSetupException
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from diskimage_builder.block_device.plugin import NodeBase
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from diskimage_builder.block_device.plugin import PluginBase
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from diskimage_builder.block_device.utils import exec_sudo
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logger = logging.getLogger(__name__)
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class MountPointNode(NodeBase):
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def __init__(self, mount_base, config, state):
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super(MountPointNode, self).__init__(config['name'], state)
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# Parameter check
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self.mount_base = mount_base
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for pname in ['base', 'mount_point']:
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if pname not in config:
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raise BlockDeviceSetupException(
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"MountPoint config needs [%s]" % pname)
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setattr(self, pname, config[pname])
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logger.debug("MountPoint created [%s]", self)
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def get_edges(self):
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"""Insert all edges
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The dependency edge is created in all cases from the base
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element (typically a mkfs) and, if this is not the 'first'
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mount-point, an edge is created from the mount-point before in
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"sorted order" (see :func:`sort_mount_points`). This ensures
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that during mounting (and umounting) the globally correct
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order is used.
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"""
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edge_from = []
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edge_to = []
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# should have been added by __init__...
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assert 'sorted_mount_points' in self.state
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sorted_mount_points = self.state['sorted_mount_points']
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# If we are not first, add our parent in the global dependency
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# list. sorted_mount_points is tuples (mount_point, node_name).
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# find ourselves in the mount_points, and our parent node
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# is one before us in node_name list.
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mount_points = [x[0] for x in sorted_mount_points]
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node_name = [x[1] for x in sorted_mount_points]
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mpi = mount_points.index(self.mount_point)
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if mpi > 0:
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dep = node_name[mpi - 1]
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edge_from.append(dep)
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edge_from.append(self.base)
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return (edge_from, edge_to)
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def create(self):
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logger.debug("mount called [%s]", self.mount_point)
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rel_mp = self.mount_point if self.mount_point[0] != '/' \
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else self.mount_point[1:]
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mount_point = os.path.join(self.mount_base, rel_mp)
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if not os.path.exists(mount_point):
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# Need to sudo this because of permissions in the new
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# file system tree.
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exec_sudo(['mkdir', '-p', mount_point])
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logger.info("Mounting [%s] to [%s]", self.name, mount_point)
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exec_sudo(["mount", self.state['filesys'][self.base]['device'],
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mount_point])
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if 'mount' not in self.state:
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self.state['mount'] = {}
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self.state['mount'][self.mount_point] \
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= {'name': self.name, 'base': self.base, 'path': mount_point}
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if 'mount_order' not in self.state:
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self.state['mount_order'] = []
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self.state['mount_order'].append(self.mount_point)
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def umount(self):
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logger.info("Called for [%s]", self.name)
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# Before calling umount, call 'fstrim' on suitable mounted
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# file systems. This discards unused blocks from the mounted
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# file system and therefore decreases the resulting image
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# size.
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#
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# A race condition can occur when trying to fstrim immediately
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# after deleting a file resulting in that free space not being
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# reclaimed. Calling sync before fstrim is a workaround for
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# this behaviour.
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# https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg02978.html
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exec_sudo(["sync"])
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if self.state['filesys'][self.base]['fstype'] != 'vfat':
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exec_sudo(["fstrim", "--verbose",
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self.state['mount'][self.mount_point]['path']])
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# Even 'fstrim' call sometimes don't solve the issue with 'busy'
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# filesystem, so we need to catch the exception and repeat unount.
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mount_point = self.state['mount'][self.mount_point]['path']
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catch = None
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for try_cnt in range(10, 1, -1):
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try:
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exec_sudo(["umount", mount_point])
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return
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except BlockDeviceSetupException as e:
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catch = e
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logger.error("umount failed (%s)", e.output.strip())
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time.sleep(3)
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logger.debug("Gave up trying to umount [%s]", mount_point)
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raise catch
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def delete(self):
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self.umount()
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def cmp_mount_order(this, other):
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"""Sort comparision function for mount-point sorting
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See if ``this`` comes before ``other`` in mount-order list. In
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words: if the other mount-point has us as it's parent, we come
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before it (are less than it). e.g. ``/var < /var/log <
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/var/log/foo``
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:param this: tuple of mount_point, node name
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:param other: tuple of mount_point, node name
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:returns int: cmp value
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"""
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# sort is only based on the mount_point.
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this, _ = this
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other, _ = other
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if this == other:
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return 0
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if other.startswith(this):
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return -1
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else:
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return 1
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class Mount(PluginBase):
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def __init__(self, config, defaults, state):
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super(Mount, self).__init__()
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if 'mount-base' not in defaults:
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raise BlockDeviceSetupException(
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"Mount default config needs 'mount-base'")
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self.node = MountPointNode(defaults['mount-base'], config, state)
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# save this new node to the global mount-point list and
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# re-order it to keep it in mount-order. Used in get_edges()
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# to ensure we build the mount graph in order
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#
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# note we can't just put the MountPointNode into the state,
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# because it's not json serialisable and we still dump the
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# state to json. that's why we have this (mount_point, name)
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# tuples and sorting trickery
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sorted_mount_points = state.get('sorted_mount_points', [])
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mount_points = [mp for mp, name in sorted_mount_points]
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if self.node.mount_point in mount_points:
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raise BlockDeviceSetupException(
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"Mount point [%s] specified more than once"
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% self.node.mount_point)
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sorted_mount_points.append((self.node.mount_point, self.node.name))
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sorted_mount_points.sort(key=functools.cmp_to_key(cmp_mount_order))
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# Save the state if it's new (otherwise this is idempotent update)
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state['sorted_mount_points'] = sorted_mount_points
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logger.debug("Ordered mounts now: %s", sorted_mount_points)
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def get_nodes(self):
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return [self.node]
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