Fix multiple issues with revert to snapshot in LVM
Reverts with the LVM driver were happening asynchronously which resulted in unreliable behavior. This change makes the reverts synchronous. Also, the driver now unexports and unmounts both the share and the snapshot during the revert (required to make the operation synchronous) which requires changing the driver interface to include the snapshot access rules in addition to the share access rules. Closes-bug: #1707943 Change-Id: Ifea1799e1d2e3963fec7e90ce3f9cb47b9f02f4f
This commit is contained in:
Ben Swartzlander
@@ -260,27 +260,26 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
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return location
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def delete_share(self, context, share, share_server=None):
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self._remove_export(context, share)
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self._unmount_device(share)
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self._delete_share(context, share)
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self._deallocate_container(share['name'])
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def _remove_export(self, ctx, share):
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"""Removes an access rules for a share."""
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mount_path = self._get_mount_path(share)
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def _unmount_device(self, share_or_snapshot):
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"""Unmount the filesystem of a share or snapshot LV."""
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mount_path = self._get_mount_path(share_or_snapshot)
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if os.path.exists(mount_path):
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# umount, may be busy
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try:
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self._execute('umount', '-f', mount_path, run_as_root=True)
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except exception.ProcessExecutionError as exc:
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if 'device is busy' in six.text_type(exc):
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raise exception.ShareBusyException(reason=share['name'])
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raise exception.ShareBusyException(
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reason=share_or_snapshot['name'])
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else:
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LOG.info('Unable to umount: %s', exc)
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LOG.error('Unable to umount: %s', exc)
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raise
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# remove dir
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try:
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os.rmdir(mount_path)
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except OSError:
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LOG.warning('Unable to delete %s', mount_path)
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self._execute('rmdir', mount_path, run_as_root=True)
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def ensure_share(self, ctx, share, share_server=None):
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"""Ensure that storage are mounted and exported."""
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@@ -336,9 +335,9 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
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else:
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raise exception.InvalidShare(reason='Wrong share protocol')
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def _mount_device(self, share, device_name):
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"""Mount LVM share and ignore if already mounted."""
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mount_path = self._get_mount_path(share)
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def _mount_device(self, share_or_snapshot, device_name):
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"""Mount LV for share or snapshot and ignore if already mounted."""
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mount_path = self._get_mount_path(share_or_snapshot)
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self._execute('mkdir', '-p', mount_path)
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try:
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self._execute('mount', device_name, mount_path,
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@@ -353,15 +352,10 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
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raise
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return mount_path
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def _unmount_device(self, share):
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mount_path = self._get_mount_path(share)
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self._execute('umount', mount_path, run_as_root=True)
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self._execute('rmdir', mount_path, run_as_root=True)
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def _get_mount_path(self, share):
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"""Returns path where share is mounted."""
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def _get_mount_path(self, share_or_snapshot):
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"""Returns path where share or snapshot is mounted."""
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return os.path.join(self.configuration.share_mount_path,
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share['name'])
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share_or_snapshot['name'])
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def _copy_volume(self, srcstr, deststr, size_in_g):
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# Use O_DIRECT to avoid thrashing the system buffer cache
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@@ -384,53 +378,56 @@ class LVMShareDriver(LVMMixin, driver.ShareDriver):
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self._extend_container(share, device_name, new_size)
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self._execute('resize2fs', device_name, run_as_root=True)
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def revert_to_snapshot(self, context, snapshot, access_rules,
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share_server=None):
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def revert_to_snapshot(self, context, snapshot, share_access_rules,
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snapshot_access_rules, share_server=None):
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share = snapshot['share']
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# Temporarily remove all access rules
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self._get_helper(share).update_access(self.share_server,
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snapshot['name'], [], [], [])
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self._get_helper(share).update_access(self.share_server,
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share['name'], [], [], [])
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# Unmount the filesystem
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self._remove_export(context, snapshot)
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# First we merge the snapshot LV and the share LV
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# This won't actually do anything until the LV is reactivated
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# Unmount the snapshot filesystem
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self._unmount_device(snapshot)
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# Unmount the share filesystem
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self._unmount_device(share)
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# Merge the snapshot LV back into the share, reverting it
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snap_lv_name = "%s/%s" % (self.configuration.lvm_share_volume_group,
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snapshot['name'])
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self._execute('lvconvert', '--merge', snap_lv_name, run_as_root=True)
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# Unmount the share so we can deactivate it
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self._unmount_device(share)
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# Deactivate the share LV
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share_lv_name = "%s/%s" % (self.configuration.lvm_share_volume_group,
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share['name'])
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self._execute('lvchange', '-an', share_lv_name, run_as_root=True)
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# Reactivate the share LV. This will trigger the merge and delete the
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# snapshot.
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self._execute('lvchange', '-ay', share_lv_name, run_as_root=True)
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# Now recreate the snapshot that was destroyed by the merge
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self._create_snapshot(context, snapshot)
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# At this point we can mount the share again
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device_name = self._get_local_path(share)
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self._mount_device(share, device_name)
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# Also remount the snapshot
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device_name = self._get_local_path(snapshot)
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self._mount_device(snapshot, device_name)
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# Lastly we add all the access rules back
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self._get_helper(share).update_access(self.share_server,
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share['name'], access_rules,
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share['name'],
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share_access_rules,
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[], [])
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snapshot_access_rules, __, __ = utils.change_rules_to_readonly(
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snapshot_access_rules, [], [])
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self._get_helper(share).update_access(self.share_server,
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snapshot['name'],
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snapshot_access_rules,
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[], [])
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def create_snapshot(self, context, snapshot, share_server=None):
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self._create_snapshot(context, snapshot)
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helper = self._get_helper(snapshot['share'])
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exports = helper.create_exports(self.share_server, snapshot['name'])
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device_name = self._get_local_path(snapshot)
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self._mount_device(snapshot, device_name)
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helper = self._get_helper(snapshot['share'])
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exports = helper.create_exports(self.share_server, snapshot['name'])
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return {'export_locations': exports}
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def delete_snapshot(self, context, snapshot, share_server=None):
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self._remove_export(context, snapshot)
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self._unmount_device(snapshot)
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super(LVMShareDriver, self).delete_snapshot(context, snapshot,
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share_server)
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