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#!/usr/bin/env python 

# 

# Copyright (C) 2020  Vates SAS - ronan.abhamon@vates.fr 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the GNU General Public License 

# along with this program.  If not, see <https://www.gnu.org/licenses/>. 

 

import base64 

import distutils.util 

import errno 

import json 

import socket 

import util 

import vhdutil 

import xs_errors 

 

MANAGER_PLUGIN = 'linstor-manager' 

 

# EMEDIUMTYPE constant (124) is not available in python2. 

EMEDIUMTYPE = 124 

 

 

def call_vhd_util_on_host(session, host_ref, method, device_path, args): 

    try: 

        response = session.xenapi.host.call_plugin( 

            host_ref, MANAGER_PLUGIN, method, args 

        ) 

    except Exception as e: 

        util.SMlog('call-plugin ({} with {}) exception: {}'.format( 

            method, args, e 

        )) 

        raise util.SMException(str(e)) 

 

    util.SMlog('call-plugin ({} with {}) returned: {}'.format( 

        method, args, response 

    )) 

 

    return response 

 

 

class LinstorCallException(util.SMException): 

    def __init__(self, cmd_err): 

        self.cmd_err = cmd_err 

 

    def __str__(self): 

        return str(self.cmd_err) 

 

 

class ErofsLinstorCallException(LinstorCallException): 

    pass 

 

 

class NoPathLinstorCallException(LinstorCallException): 

    pass 

 

 

def linstorhostcall(local_method, remote_method): 

    def decorated(response_parser): 

        def wrapper(*args, **kwargs): 

            self = args[0] 

            vdi_uuid = args[1] 

 

            device_path = self._linstor.build_device_path( 

                self._linstor.get_volume_name(vdi_uuid) 

            ) 

 

            # A. Try a call using directly the DRBD device to avoid 

            # remote request. 

 

            # Try to read locally if the device is not in use or if the device 

            # is up to date and not diskless. 

            (node_names, in_use_by) = \ 

                self._linstor.find_up_to_date_diskful_nodes(vdi_uuid) 

 

            local_e = None 

            try: 

                if not in_use_by or socket.gethostname() in node_names: 

                    return self._call_local_vhd_util(local_method, device_path, *args[2:], **kwargs) 

            except ErofsLinstorCallException as e: 

                local_e = e.cmd_err 

            except Exception as e: 

                local_e = e 

 

            util.SMlog( 

                'unable to execute `{}` locally, retry using a readable host... (cause: {})'.format( 

                    remote_method, local_e if local_e else 'local diskless + in use or not up to date' 

                ) 

            ) 

 

            if in_use_by: 

                node_names = {in_use_by} 

 

            # B. Execute the plugin on master or slave. 

            remote_args = { 

                'devicePath': device_path, 

                'groupName': self._linstor.group_name 

            } 

            remote_args.update(**kwargs) 

            remote_args = {str(key): str(value) for key, value in remote_args.iteritems()} 

 

            try: 

                def remote_call(): 

                    host_ref = self._get_readonly_host(vdi_uuid, device_path, node_names) 

                    return call_vhd_util_on_host(self._session, host_ref, remote_method, device_path, remote_args) 

                response = util.retry(remote_call, 5, 2) 

            except Exception as remote_e: 

                self._raise_openers_exception(device_path, local_e or remote_e) 

 

            return response_parser(self, vdi_uuid, response) 

        return wrapper 

    return decorated 

 

 

def linstormodifier(): 

    def decorated(func): 

        def wrapper(*args, **kwargs): 

            self = args[0] 

 

            ret = func(*args, **kwargs) 

            self._linstor.invalidate_resource_cache() 

            return ret 

        return wrapper 

    return decorated 

 

 

class LinstorVhdUtil: 

    def __init__(self, session, linstor): 

        self._session = session 

        self._linstor = linstor 

 

    # -------------------------------------------------------------------------- 

    # Getters: read locally and try on another host in case of failure. 

    # -------------------------------------------------------------------------- 

 

    def check(self, vdi_uuid, ignore_missing_footer=False, fast=False): 

        kwargs = { 

            'ignoreMissingFooter': ignore_missing_footer, 

            'fast': fast 

        } 

        return self._check(vdi_uuid, **kwargs)  # pylint: disable = E1123 

 

    @linstorhostcall(vhdutil.check, 'check') 

    def _check(self, vdi_uuid, response): 

        return distutils.util.strtobool(response) 

 

    def get_vhd_info(self, vdi_uuid, include_parent=True): 

        kwargs = { 

            'includeParent': include_parent, 

            'resolveParent': False 

        } 

        # TODO: Replace pylint comment with this feature when possible: 

        # https://github.com/PyCQA/pylint/pull/2926 

        return self._get_vhd_info(vdi_uuid, self._extract_uuid, **kwargs)  # pylint: disable = E1123 

 

    @linstorhostcall(vhdutil.getVHDInfo, 'getVHDInfo') 

    def _get_vhd_info(self, vdi_uuid, response): 

        obj = json.loads(response) 

 

        vhd_info = vhdutil.VHDInfo(vdi_uuid) 

        vhd_info.sizeVirt = obj['sizeVirt'] 

        vhd_info.sizePhys = obj['sizePhys'] 

        if 'parentPath' in obj: 

            vhd_info.parentPath = obj['parentPath'] 

            vhd_info.parentUuid = obj['parentUuid'] 

        vhd_info.hidden = obj['hidden'] 

        vhd_info.path = obj['path'] 

 

        return vhd_info 

 

    @linstorhostcall(vhdutil.hasParent, 'hasParent') 

    def has_parent(self, vdi_uuid, response): 

        return distutils.util.strtobool(response) 

 

    def get_parent(self, vdi_uuid): 

        return self._get_parent(vdi_uuid, self._extract_uuid) 

 

    @linstorhostcall(vhdutil.getParent, 'getParent') 

    def _get_parent(self, vdi_uuid, response): 

        return response 

 

    @linstorhostcall(vhdutil.getSizeVirt, 'getSizeVirt') 

    def get_size_virt(self, vdi_uuid, response): 

        return int(response) 

 

    @linstorhostcall(vhdutil.getSizePhys, 'getSizePhys') 

    def get_size_phys(self, vdi_uuid, response): 

        return int(response) 

 

    @linstorhostcall(vhdutil.getDepth, 'getDepth') 

    def get_depth(self, vdi_uuid, response): 

        return int(response) 

 

    @linstorhostcall(vhdutil.getKeyHash, 'getKeyHash') 

    def get_key_hash(self, vdi_uuid, response): 

        return response or None 

 

    @linstorhostcall(vhdutil.getBlockBitmap, 'getBlockBitmap') 

    def get_block_bitmap(self, vdi_uuid, response): 

        return base64.b64decode(response) 

 

    @linstorhostcall('_get_drbd_size', 'getDrbdSize') 

    def get_drbd_size(self, vdi_uuid, response): 

        return int(response) 

 

    def _get_drbd_size(self, path): 

        (ret, stdout, stderr) = util.doexec(['blockdev', '--getsize64', path]) 

        if ret == 0: 

            return int(stdout.strip()) 

        raise util.SMException('Failed to get DRBD size: {}'.format(stderr)) 

 

    # -------------------------------------------------------------------------- 

    # Setters: only used locally. 

    # -------------------------------------------------------------------------- 

 

    @linstormodifier() 

    def create(self, path, size, static, msize=0): 

        return self._call_local_vhd_util_or_fail(vhdutil.create, path, size, static, msize) 

 

    @linstormodifier() 

    def set_size_virt_fast(self, path, size): 

        return self._call_local_vhd_util_or_fail(vhdutil.setSizeVirtFast, path, size) 

 

    @linstormodifier() 

    def set_size_phys(self, path, size, debug=True): 

        return self._call_local_vhd_util_or_fail(vhdutil.setSizePhys, path, size, debug) 

 

    @linstormodifier() 

    def set_parent(self, path, parentPath, parentRaw=False): 

        return self._call_local_vhd_util_or_fail(vhdutil.setParent, path, parentPath, parentRaw) 

 

    @linstormodifier() 

    def set_hidden(self, path, hidden=True): 

        return self._call_local_vhd_util_or_fail(vhdutil.setHidden, path, hidden) 

 

    @linstormodifier() 

    def set_key(self, path, key_hash): 

        return self._call_local_vhd_util_or_fail(vhdutil.setKey, path, key_hash) 

 

    @linstormodifier() 

    def kill_data(self, path): 

        return self._call_local_vhd_util_or_fail(vhdutil.killData, path) 

 

    @linstormodifier() 

    def snapshot(self, path, parent, parentRaw, msize=0, checkEmpty=True): 

        return self._call_local_vhd_util_or_fail(vhdutil.snapshot, path, parent, parentRaw, msize, checkEmpty) 

 

    # -------------------------------------------------------------------------- 

    # Remote setters: write locally and try on another host in case of failure. 

    # -------------------------------------------------------------------------- 

 

    @linstormodifier() 

    def force_parent(self, path, parentPath, parentRaw=False): 

        kwargs = { 

            'parentPath': str(parentPath), 

            'parentRaw': parentRaw 

        } 

        return self._call_vhd_util(vhdutil.setParent, 'setParent', path, use_parent=False, **kwargs) 

 

    @linstormodifier() 

    def force_coalesce(self, path): 

        return self._call_vhd_util(vhdutil.coalesce, 'coalesce', path, use_parent=True) 

 

    @linstormodifier() 

    def force_repair(self, path): 

        return self._call_vhd_util(vhdutil.repair, 'repair', path, use_parent=False) 

 

    # -------------------------------------------------------------------------- 

    # Helpers. 

    # -------------------------------------------------------------------------- 

 

    def _extract_uuid(self, device_path): 

        # TODO: Remove new line in the vhdutil module. Not here. 

        return self._linstor.get_volume_uuid_from_device_path( 

            device_path.rstrip('\n') 

        ) 

 

    def _get_readonly_host(self, vdi_uuid, device_path, node_names): 

        """ 

        When vhd-util is called to fetch VDI info we must find a 

        diskful DRBD disk to read the data. It's the goal of this function. 

        Why? Because when a VHD is open in RO mode, the LVM layer is used 

        directly to bypass DRBD verifications (we can have only one process 

        that reads/writes to disk with DRBD devices). 

        """ 

 

        if not node_names: 

            raise xs_errors.XenError( 

                'VDIUnavailable', 

                opterr='Unable to find diskful node: {} (path={})' 

                .format(vdi_uuid, device_path) 

            ) 

 

        hosts = self._session.xenapi.host.get_all_records() 

        for host_ref, host_record in hosts.items(): 

            if host_record['hostname'] in node_names: 

                return host_ref 

 

        raise xs_errors.XenError( 

            'VDIUnavailable', 

            opterr='Unable to find a valid host from VDI: {} (path={})' 

            .format(vdi_uuid, device_path) 

        ) 

 

    # -------------------------------------------------------------------------- 

 

    def _raise_openers_exception(self, device_path, e): 

        if isinstance(e, util.CommandException): 

            e_str = 'cmd: `{}`, code: `{}`, reason: `{}`'.format(e.cmd, e.code, e.reason) 

        else: 

            e_str = str(e) 

 

        try: 

            volume_uuid = self._linstor.get_volume_uuid_from_device_path( 

                device_path 

            ) 

            e_wrapper = Exception( 

                e_str + ' (openers: {})'.format( 

                    self._linstor.get_volume_openers(volume_uuid) 

                ) 

            ) 

        except Exception as illformed_e: 

            e_wrapper = Exception( 

                e_str + ' (unable to get openers: {})'.format(illformed_e) 

            ) 

        util.SMlog('raise opener exception: {}'.format(e_wrapper)) 

        raise e_wrapper  # pylint: disable = E0702 

 

    def _call_local_vhd_util(self, local_method, device_path, *args, **kwargs): 

        if isinstance(local_method, str): 

            local_method = getattr(self, local_method) 

 

        try: 

            def local_call(): 

                try: 

                    return local_method(device_path, *args, **kwargs) 

                except util.CommandException as e: 

                    if e.code == errno.EROFS or e.code == EMEDIUMTYPE: 

                        raise ErofsLinstorCallException(e)  # Break retry calls. 

                    if e.code == errno.ENOENT: 

                        raise NoPathLinstorCallException(e) 

                    raise e 

            # Retry only locally if it's not an EROFS exception. 

            return util.retry(local_call, 5, 2, exceptions=[util.CommandException]) 

        except util.CommandException as e: 

            util.SMlog('failed to execute locally vhd-util (sys {})'.format(e.code)) 

            raise e 

 

    def _call_local_vhd_util_or_fail(self, local_method, device_path, *args, **kwargs): 

        try: 

            return self._call_local_vhd_util(local_method, device_path, *args, **kwargs) 

        except ErofsLinstorCallException as e: 

            # Volume is locked on a host, find openers. 

            self._raise_openers_exception(device_path, e.cmd_err) 

 

    def _call_vhd_util(self, local_method, remote_method, device_path, use_parent, *args, **kwargs): 

        # Note: `use_parent` exists to know if the VHD parent is used by the local/remote method. 

        # Normally in case of failure, if the parent is unused we try to execute the method on 

        # another host using the DRBD opener list. In the other case, if the parent is required, 

        # we must check where this last one is open instead of the child. 

 

        # A. Try to write locally... 

        try: 

            return self._call_local_vhd_util(local_method, device_path, *args, **kwargs) 

        except Exception: 

            pass 

 

        util.SMlog('unable to execute `{}` locally, retry using a writable host...'.format(remote_method)) 

 

        # B. Execute the command on another host. 

        # B.1. Get host list. 

        try: 

            hosts = self._session.xenapi.host.get_all_records() 

        except Exception as e: 

            raise xs_errors.XenError( 

                'VDIUnavailable', 

                opterr='Unable to get host list to run vhd-util command `{}` (path={}): {}' 

                .format(remote_method, device_path, e) 

            ) 

 

        # B.2. Prepare remote args. 

        remote_args = { 

            'devicePath': device_path, 

            'groupName': self._linstor.group_name 

        } 

        remote_args.update(**kwargs) 

        remote_args = {str(key): str(value) for key, value in remote_args.iteritems()} 

 

        volume_uuid = self._linstor.get_volume_uuid_from_device_path( 

            device_path 

        ) 

        parent_volume_uuid = None 

        if use_parent: 

            parent_volume_uuid = self.get_parent(volume_uuid) 

 

        openers_uuid = parent_volume_uuid if use_parent else volume_uuid 

 

        # B.3. Call! 

        def remote_call(): 

            try: 

                all_openers = self._linstor.get_volume_openers(openers_uuid) 

            except Exception as e: 

                raise xs_errors.XenError( 

                    'VDIUnavailable', 

                    opterr='Unable to get DRBD openers to run vhd-util command `{}` (path={}): {}' 

                    .format(remote_method, device_path, e) 

                ) 

 

            no_host_found = True 

            for hostname, openers in all_openers.iteritems(): 

                if not openers: 

                    continue 

 

                try: 

                    host_ref = next(ref for ref, rec in hosts.iteritems() if rec['hostname'] == hostname) 

                except StopIteration: 

                    continue 

 

                no_host_found = False 

                try: 

                    return call_vhd_util_on_host(self._session, host_ref, remote_method, device_path, remote_args) 

                except Exception: 

                    pass 

 

            if no_host_found: 

                try: 

                    return local_method(device_path, *args, **kwargs) 

                except Exception as e: 

                    self._raise_openers_exception(device_path, e) 

 

            raise xs_errors.XenError( 

                'VDIUnavailable', 

                opterr='No valid host found to run vhd-util command `{}` (path=`{}`, openers=`{}`): {}' 

                .format(remote_method, device_path, openers, e) 

            ) 

        return util.retry(remote_call, 5, 2)