35a1e7bee9
Currently we keep a global list of mount-points defined in the configuration and automatically setup dependencies between mount nodes based on their global "mount order" (i.e. higher directories mount first). The current method for achieving this is roughly to add the mount points to a dictionary indexed my mount-point, then at "get_edge()" call build the sorted list ... unless it has already been built because this gets called for every node. It seems much simpler to simply keep a sorted list of the MountPointNode objects as we add them. We don't need to implement a sorting algorithm then, we can just use sort() and implement __lt__ for the nodes. I believe the existing mount-order unit testing is sufficient; I'm struggling to find a valid configuration where the mount-order is *not* correctly specified in the configuration graph. Change-Id: Idc05cdf42d95e230b9906773aa2b4a3b0f075598
128 lines
4.5 KiB
Python
128 lines
4.5 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 logging
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import os
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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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# The order of mounting and unmounting is important.
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sorted_mount_points = []
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class MountPointNode(NodeBase):
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def __init__(self, mount_base, config):
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super(MountPointNode, self).__init__(config['name'])
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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 __lt__(self, other):
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# in words: if the other mount-point has us as it's
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# parent, we come before it (less than it). e.g.
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# /var < /var/log < /var/log/foo
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return other.mount_point.startswith(self.mount_point)
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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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# If we are not first, add our parent in the global dependency
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# list
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mpi = sorted_mount_points.index(self)
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if mpi > 0:
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dep = sorted_mount_points[mpi - 1]
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edge_from.append(dep.name)
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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, state, rollback):
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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", state['filesys'][self.base]['device'],
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mount_point])
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if 'mount' not in state:
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state['mount'] = {}
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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 state:
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state['mount_order'] = []
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state['mount_order'].append(self.mount_point)
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def umount(self, state):
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logger.info("Called for [%s]", self.name)
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exec_sudo(["umount", state['mount'][self.mount_point]['path']])
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def delete(self, state):
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self.umount(state)
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class Mount(PluginBase):
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def __init__(self, config, defaults):
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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)
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# save this new node to the global mount-point list and
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# re-order it.
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global sorted_mount_points
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mount_points = [x.mount_point for x 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)
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sorted_mount_points.sort()
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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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