Hot-keys on this page

r m x p   toggle line displays

j k   next/prev highlighted chunk

0   (zero) top of page

1   (one) first highlighted chunk

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

347

348

349

350

351

352

353

354

355

356

357

358

359

360

361

362

363

364

365

366

367

368

369

370

371

372

373

374

375

376

377

378

379

380

381

382

383

384

385

386

387

388

389

390

391

392

393

394

395

396

397

398

399

400

401

402

403

404

405

406

407

408

409

410

411

412

413

414

415

416

417

418

419

420

421

422

423

424

425

426

427

428

429

430

431

432

433

434

435

436

437

438

439

440

441

442

443

444

445

446

447

448

449

450

451

452

453

454

455

456

457

458

459

460

461

462

463

464

465

466

467

468

469

470

471

472

473

474

475

476

477

478

479

480

481

482

483

484

485

486

487

488

489

490

491

492

493

494

495

496

497

498

499

500

501

502

503

504

505

506

507

508

509

510

511

512

513

514

515

516

517

518

519

520

521

522

523

524

525

526

527

528

529

530

531

532

533

534

535

536

537

538

539

540

541

542

543

544

545

546

547

548

549

550

551

552

553

554

555

556

557

558

559

560

561

562

563

564

565

566

567

568

569

570

571

572

573

574

575

576

577

578

579

580

581

582

583

584

585

586

587

588

589

590

591

592

593

594

595

596

597

598

599

600

601

602

#!/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/>. 

 

from linstorjournaler import LinstorJournaler 

from linstorvolumemanager import LinstorVolumeManager 

import base64 

import distutils.util 

import errno 

import json 

import socket 

import time 

import util 

import vhdutil 

import xs_errors 

 

MANAGER_PLUGIN = 'linstor-manager' 

 

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

EMEDIUMTYPE = 124 

 

 

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

    host_rec = session.xenapi.host.get_record(host_ref) 

    host_uuid = host_rec['uuid'] 

 

    try: 

        response = session.xenapi.host.call_plugin( 

            host_ref, MANAGER_PLUGIN, method, args 

        ) 

    except Exception as e: 

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

            host_uuid, method, args, e 

        )) 

        raise util.SMException(str(e)) 

 

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

        host_uuid, method, args, response 

    )) 

 

    return response 

 

 

def check_ex(path, ignoreMissingFooter = False, fast = False): 

    cmd = [vhdutil.VHD_UTIL, "check", vhdutil.OPT_LOG_ERR, "-n", path] 

    if ignoreMissingFooter: 

        cmd.append("-i") 

    if fast: 

        cmd.append("-B") 

 

    vhdutil.ioretry(cmd) 

 

 

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) 

            ) 

 

            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: 

                host_ref_attached = util.get_hosts_attached_on(self._session, [vdi_uuid])[0] 

                if host_ref_attached: 

                    response = call_remote_method( 

                        self._session, host_ref_attached, remote_method, device_path, remote_args 

                    ) 

                    return response_parser(self, vdi_uuid, response) 

            except Exception as e: 

                util.SMlog( 

                    'Failed to call method on attached host. Trying local access... (cause: {})'.format(e), 

                    priority=util.LOG_DEBUG 

                ) 

 

            try: 

                master_ref = self._session.xenapi.pool.get_all_records().values()[0]['master'] 

                response = call_remote_method(self._session, master_ref, remote_method, device_path, remote_args) 

                return response_parser(self, vdi_uuid, response) 

            except Exception as e: 

                util.SMlog( 

                    'Failed to call method on master host. Finding primary node... (cause: {})'.format(e), 

                    priority=util.LOG_DEBUG 

                ) 

 

            nodes, primary_hostname = self._linstor.find_up_to_date_diskful_nodes(vdi_uuid) 

            if primary_hostname: 

                try: 

                    host_ref = self._get_readonly_host(vdi_uuid, device_path, {primary_hostname}) 

                    response = call_remote_method(self._session, host_ref, remote_method, device_path, remote_args) 

                    return response_parser(self, vdi_uuid, response) 

                except Exception as remote_e: 

                    self._raise_openers_exception(device_path, remote_e) 

            else: 

                util.SMlog( 

                    'Couldn\'t get primary for {}. Trying with another node...'.format(vdi_uuid), 

                    priority=util.LOG_DEBUG 

                ) 

                try: 

                    host = self._get_readonly_host(vdi_uuid, device_path, nodes) 

                    response = call_remote_method(self._session, host, remote_method, device_path, remote_args) 

                    return response_parser(self, vdi_uuid, response) 

                except Exception as remote_e: 

                    self._raise_openers_exception(device_path, remote_e) 

 

        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: 

    MAX_SIZE = 2 * 1024 * 1024 * 1024 * 1024  # Max VHD size. 

 

    def __init__(self, session, linstor): 

        self._session = session 

        self._linstor = linstor 

 

    def create_chain_paths(self, vdi_uuid, readonly=False): 

        # OPTIMIZE: Add a limit_to_first_allocated_block param to limit vhdutil calls. 

        # Useful for the snapshot code algorithm. 

 

        leaf_vdi_path = self._linstor.get_device_path(vdi_uuid) 

        path = leaf_vdi_path 

        while True: 

            if not util.pathexists(path): 

                raise xs_errors.XenError( 

                    'VDIUnavailable', opterr='Could not find: {}'.format(path) 

                ) 

 

            # Diskless path can be created on the fly, ensure we can open it. 

            def check_volume_usable(): 

                while True: 

                    try: 

                        with open(path, 'r' if readonly else 'r+'): 

                            pass 

                    except IOError as e: 

                        if e.errno == errno.ENODATA: 

                            time.sleep(2) 

                            continue 

                        if e.errno == errno.EROFS: 

                            util.SMlog('Volume not attachable because RO. Openers: {}'.format( 

                                self._linstor.get_volume_openers(vdi_uuid) 

                            )) 

                        raise 

                    break 

            util.retry(check_volume_usable, 15, 2) 

 

            vdi_uuid = self.get_vhd_info(vdi_uuid).parentUuid 

            if not vdi_uuid: 

                break 

            path = self._linstor.get_device_path(vdi_uuid) 

            readonly = True  # Non-leaf is always readonly. 

 

        return leaf_vdi_path 

 

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

    # 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 

        } 

        try: 

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

            return True 

        except Exception as e: 

            util.SMlog('Call to `check` failed: {}'.format(e)) 

            return False 

 

    @linstorhostcall(check_ex, '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_method_or_fail(vhdutil.create, path, size, static, msize) 

 

    @linstormodifier() 

    def set_size_virt(self, path, size, jfile): 

        return self._call_local_method_or_fail(vhdutil.setSizeVirt, path, size, jfile) 

 

    @linstormodifier() 

    def set_size_virt_fast(self, path, size): 

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

 

    @linstormodifier() 

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

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

 

    @linstormodifier() 

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

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

 

    @linstormodifier() 

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

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

 

    @linstormodifier() 

    def set_key(self, path, key_hash): 

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

 

    @linstormodifier() 

    def kill_data(self, path): 

        return self._call_local_method_or_fail(vhdutil.killData, path) 

 

    @linstormodifier() 

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

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

 

    def inflate(self, journaler, vdi_uuid, vdi_path, new_size, old_size): 

        # Only inflate if the LINSTOR volume capacity is not enough. 

        new_size = LinstorVolumeManager.round_up_volume_size(new_size) 

        if new_size <= old_size: 

            return 

 

        util.SMlog( 

            'Inflate {} (size={}, previous={})' 

            .format(vdi_path, new_size, old_size) 

        ) 

 

        journaler.create( 

            LinstorJournaler.INFLATE, vdi_uuid, old_size 

        ) 

        self._linstor.resize_volume(vdi_uuid, new_size) 

 

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

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

        result_size = self.get_drbd_size(vdi_uuid)  # pylint: disable = E1120 

        if result_size < new_size: 

            util.SMlog( 

                'WARNING: Cannot inflate volume to {}B, result size: {}B' 

                .format(new_size, result_size) 

            ) 

 

        self._zeroize(vdi_path, result_size - vhdutil.VHD_FOOTER_SIZE) 

        self.set_size_phys(vdi_path, result_size, False) 

        journaler.remove(LinstorJournaler.INFLATE, vdi_uuid) 

 

    def deflate(self, vdi_path, new_size, old_size, zeroize=False): 

        if zeroize: 

            assert old_size > vhdutil.VHD_FOOTER_SIZE 

            self._zeroize(vdi_path, old_size - vhdutil.VHD_FOOTER_SIZE) 

 

        new_size = LinstorVolumeManager.round_up_volume_size(new_size) 

        if new_size >= old_size: 

            return 

 

        util.SMlog( 

            'Deflate {} (new size={}, previous={})' 

            .format(vdi_path, new_size, old_size) 

        ) 

 

        self.set_size_phys(vdi_path, new_size) 

        # TODO: Change the LINSTOR volume size using linstor.resize_volume. 

 

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

    # 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_method(vhdutil.setParent, 'setParent', path, use_parent=False, **kwargs) 

 

    @linstormodifier() 

    def force_coalesce(self, path): 

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

 

    @linstormodifier() 

    def force_repair(self, path): 

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

 

    @linstormodifier() 

    def force_deflate(self, path, newSize, oldSize, zeroize): 

        kwargs = { 

            'newSize': newSize, 

            'oldSize': oldSize, 

            'zeroize': zeroize 

        } 

        return self._call_method('_force_deflate', 'deflate', path, use_parent=False, **kwargs) 

 

    def _force_deflate(self, path, newSize, oldSize, zeroize): 

        self.deflate(path, newSize, oldSize, zeroize) 

 

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

    # Static helpers. 

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

 

    @classmethod 

    def compute_volume_size(cls, virtual_size, image_type): 

        if image_type == vhdutil.VDI_TYPE_VHD: 

            # All LINSTOR VDIs have the metadata area preallocated for 

            # the maximum possible virtual size (for fast online VDI.resize). 

            meta_overhead = vhdutil.calcOverheadEmpty(cls.MAX_SIZE) 

            bitmap_overhead = vhdutil.calcOverheadBitmap(virtual_size) 

            virtual_size += meta_overhead + bitmap_overhead 

        elif image_type != vhdutil.VDI_TYPE_RAW: 

            raise Exception('Invalid image type: {}'.format(image_type)) 

 

        return LinstorVolumeManager.round_up_volume_size(virtual_size) 

 

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

    # 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_method(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_method_or_fail(self, local_method, device_path, *args, **kwargs): 

        try: 

            return self._call_local_method(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_method(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. 

 

        if isinstance(local_method, str): 

            local_method = getattr(self, local_method) 

 

        # A. Try to write locally... 

        try: 

            return self._call_local_method(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_remote_method(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) 

            ) 

        return util.retry(remote_call, 5, 2) 

 

    @staticmethod 

    def _zeroize(path, size): 

        if not util.zeroOut(path, size, vhdutil.VHD_FOOTER_SIZE): 

            raise xs_errors.XenError( 

                'EIO', 

                opterr='Failed to zero out VHD footer {}'.format(path) 

            )