1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Copyright (c) 2012 by Delphix. All rights reserved.
25 */
26
27 /*
28 * Virtual Device Labels
29 * ---------------------
30 *
31 * The vdev label serves several distinct purposes:
32 *
33 * 1. Uniquely identify this device as part of a ZFS pool and confirm its
34 * identity within the pool.
35 *
36 * 2. Verify that all the devices given in a configuration are present
37 * within the pool.
38 *
39 * 3. Determine the uberblock for the pool.
40 *
41 * 4. In case of an import operation, determine the configuration of the
42 * toplevel vdev of which it is a part.
43 *
44 * 5. If an import operation cannot find all the devices in the pool,
45 * provide enough information to the administrator to determine which
46 * devices are missing.
47 *
48 * It is important to note that while the kernel is responsible for writing the
49 * label, it only consumes the information in the first three cases. The
50 * latter information is only consumed in userland when determining the
51 * configuration to import a pool.
52 *
53 *
54 * Label Organization
55 * ------------------
56 *
57 * Before describing the contents of the label, it's important to understand how
58 * the labels are written and updated with respect to the uberblock.
59 *
60 * When the pool configuration is altered, either because it was newly created
61 * or a device was added, we want to update all the labels such that we can deal
62 * with fatal failure at any point. To this end, each disk has two labels which
63 * are updated before and after the uberblock is synced. Assuming we have
64 * labels and an uberblock with the following transaction groups:
65 *
66 * L1 UB L2
67 * +------+ +------+ +------+
68 * | | | | | |
69 * | t10 | | t10 | | t10 |
70 * | | | | | |
71 * +------+ +------+ +------+
72 *
73 * In this stable state, the labels and the uberblock were all updated within
74 * the same transaction group (10). Each label is mirrored and checksummed, so
75 * that we can detect when we fail partway through writing the label.
76 *
77 * In order to identify which labels are valid, the labels are written in the
78 * following manner:
79 *
80 * 1. For each vdev, update 'L1' to the new label
81 * 2. Update the uberblock
82 * 3. For each vdev, update 'L2' to the new label
83 *
84 * Given arbitrary failure, we can determine the correct label to use based on
85 * the transaction group. If we fail after updating L1 but before updating the
86 * UB, we will notice that L1's transaction group is greater than the uberblock,
87 * so L2 must be valid. If we fail after writing the uberblock but before
88 * writing L2, we will notice that L2's transaction group is less than L1, and
89 * therefore L1 is valid.
90 *
91 * Another added complexity is that not every label is updated when the config
92 * is synced. If we add a single device, we do not want to have to re-write
93 * every label for every device in the pool. This means that both L1 and L2 may
94 * be older than the pool uberblock, because the necessary information is stored
95 * on another vdev.
96 *
97 *
98 * On-disk Format
99 * --------------
100 *
101 * The vdev label consists of two distinct parts, and is wrapped within the
102 * vdev_label_t structure. The label includes 8k of padding to permit legacy
103 * VTOC disk labels, but is otherwise ignored.
104 *
105 * The first half of the label is a packed nvlist which contains pool wide
106 * properties, per-vdev properties, and configuration information. It is
107 * described in more detail below.
108 *
109 * The latter half of the label consists of a redundant array of uberblocks.
110 * These uberblocks are updated whenever a transaction group is committed,
111 * or when the configuration is updated. When a pool is loaded, we scan each
112 * vdev for the 'best' uberblock.
113 *
114 *
115 * Configuration Information
116 * -------------------------
117 *
118 * The nvlist describing the pool and vdev contains the following elements:
119 *
120 * version ZFS on-disk version
121 * name Pool name
122 * state Pool state
123 * txg Transaction group in which this label was written
124 * pool_guid Unique identifier for this pool
125 * vdev_tree An nvlist describing vdev tree.
126 * features_for_read
127 * An nvlist of the features necessary for reading the MOS.
128 *
129 * Each leaf device label also contains the following:
130 *
131 * top_guid Unique ID for top-level vdev in which this is contained
132 * guid Unique ID for the leaf vdev
133 *
134 * The 'vs' configuration follows the format described in 'spa_config.c'.
135 */
136
137 #include <sys/zfs_context.h>
138 #include <sys/spa.h>
139 #include <sys/spa_impl.h>
140 #include <sys/dmu.h>
141 #include <sys/zap.h>
142 #include <sys/vdev.h>
143 #include <sys/vdev_impl.h>
144 #include <sys/uberblock_impl.h>
145 #include <sys/metaslab.h>
146 #include <sys/zio.h>
147 #include <sys/dsl_scan.h>
148 #include <sys/fs/zfs.h>
149
150 /*
151 * Basic routines to read and write from a vdev label.
152 * Used throughout the rest of this file.
153 */
154 uint64_t
155 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
156 {
157 ASSERT(offset < sizeof (vdev_label_t));
158 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
159
160 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
161 0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
162 }
163
164 /*
165 * Returns back the vdev label associated with the passed in offset.
166 */
167 int
168 vdev_label_number(uint64_t psize, uint64_t offset)
169 {
170 int l;
171
172 if (offset >= psize - VDEV_LABEL_END_SIZE) {
173 offset -= psize - VDEV_LABEL_END_SIZE;
174 offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
175 }
176 l = offset / sizeof (vdev_label_t);
177 return (l < VDEV_LABELS ? l : -1);
178 }
179
180 static void
181 vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
182 uint64_t size, zio_done_func_t *done, void *private, int flags)
183 {
184 ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
185 SCL_STATE_ALL);
186 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
187
188 zio_nowait(zio_read_phys(zio, vd,
189 vdev_label_offset(vd->vdev_psize, l, offset),
190 size, buf, ZIO_CHECKSUM_LABEL, done, private,
191 ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
192 }
193
194 static void
195 vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
196 uint64_t size, zio_done_func_t *done, void *private, int flags)
197 {
198 ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
199 (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
200 (SCL_CONFIG | SCL_STATE) &&
201 dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
202 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
203
204 zio_nowait(zio_write_phys(zio, vd,
205 vdev_label_offset(vd->vdev_psize, l, offset),
206 size, buf, ZIO_CHECKSUM_LABEL, done, private,
207 ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
208 }
209
210 /*
211 * Generate the nvlist representing this vdev's config.
212 */
213 nvlist_t *
214 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
215 vdev_config_flag_t flags)
216 {
217 nvlist_t *nv = NULL;
218
219 VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
220
221 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
222 vd->vdev_ops->vdev_op_type) == 0);
223 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
224 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id)
225 == 0);
226 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0);
227
228 if (vd->vdev_path != NULL)
229 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH,
230 vd->vdev_path) == 0);
231
232 if (vd->vdev_devid != NULL)
233 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID,
234 vd->vdev_devid) == 0);
235
236 if (vd->vdev_physpath != NULL)
237 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
238 vd->vdev_physpath) == 0);
239
240 if (vd->vdev_fru != NULL)
241 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_FRU,
242 vd->vdev_fru) == 0);
243
244 if (vd->vdev_nparity != 0) {
245 ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
246 VDEV_TYPE_RAIDZ) == 0);
247
248 /*
249 * Make sure someone hasn't managed to sneak a fancy new vdev
250 * into a crufty old storage pool.
251 */
252 ASSERT(vd->vdev_nparity == 1 ||
253 (vd->vdev_nparity <= 2 &&
254 spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
255 (vd->vdev_nparity <= 3 &&
256 spa_version(spa) >= SPA_VERSION_RAIDZ3));
257
258 /*
259 * Note that we'll add the nparity tag even on storage pools
260 * that only support a single parity device -- older software
261 * will just ignore it.
262 */
263 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY,
264 vd->vdev_nparity) == 0);
265 }
266
267 if (vd->vdev_wholedisk != -1ULL)
268 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
269 vd->vdev_wholedisk) == 0);
270
271 if (vd->vdev_not_present)
272 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0);
273
274 if (vd->vdev_isspare)
275 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0);
276
277 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
278 vd == vd->vdev_top) {
279 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
280 vd->vdev_ms_array) == 0);
281 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
282 vd->vdev_ms_shift) == 0);
283 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT,
284 vd->vdev_ashift) == 0);
285 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
286 vd->vdev_asize) == 0);
287 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG,
288 vd->vdev_islog) == 0);
289 if (vd->vdev_removing)
290 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
291 vd->vdev_removing) == 0);
292 }
293
294 if (vd->vdev_dtl_smo.smo_object != 0)
295 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
296 vd->vdev_dtl_smo.smo_object) == 0);
297
298 if (vd->vdev_crtxg)
299 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
300 vd->vdev_crtxg) == 0);
301
302 if (getstats) {
303 vdev_stat_t vs;
304 pool_scan_stat_t ps;
305
306 vdev_get_stats(vd, &vs);
307 VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
308 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0);
309
310 /* provide either current or previous scan information */
311 if (spa_scan_get_stats(spa, &ps) == 0) {
312 VERIFY(nvlist_add_uint64_array(nv,
313 ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
314 sizeof (pool_scan_stat_t) / sizeof (uint64_t))
315 == 0);
316 }
317 }
318
319 if (!vd->vdev_ops->vdev_op_leaf) {
320 nvlist_t **child;
321 int c, idx;
322
323 ASSERT(!vd->vdev_ishole);
324
325 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
326 KM_SLEEP);
327
328 for (c = 0, idx = 0; c < vd->vdev_children; c++) {
329 vdev_t *cvd = vd->vdev_child[c];
330
331 /*
332 * If we're generating an nvlist of removing
333 * vdevs then skip over any device which is
334 * not being removed.
335 */
336 if ((flags & VDEV_CONFIG_REMOVING) &&
337 !cvd->vdev_removing)
338 continue;
339
340 child[idx++] = vdev_config_generate(spa, cvd,
341 getstats, flags);
342 }
343
344 if (idx) {
345 VERIFY(nvlist_add_nvlist_array(nv,
346 ZPOOL_CONFIG_CHILDREN, child, idx) == 0);
347 }
348
349 for (c = 0; c < idx; c++)
350 nvlist_free(child[c]);
351
352 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
353
354 } else {
355 const char *aux = NULL;
356
357 if (vd->vdev_offline && !vd->vdev_tmpoffline)
358 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE,
359 B_TRUE) == 0);
360 if (vd->vdev_resilvering)
361 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVERING,
362 B_TRUE) == 0);
363 if (vd->vdev_faulted)
364 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED,
365 B_TRUE) == 0);
366 if (vd->vdev_degraded)
367 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED,
368 B_TRUE) == 0);
369 if (vd->vdev_removed)
370 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED,
371 B_TRUE) == 0);
372 if (vd->vdev_unspare)
373 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE,
374 B_TRUE) == 0);
375 if (vd->vdev_ishole)
376 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE,
377 B_TRUE) == 0);
378
379 switch (vd->vdev_stat.vs_aux) {
380 case VDEV_AUX_ERR_EXCEEDED:
381 aux = "err_exceeded";
382 break;
383
384 case VDEV_AUX_EXTERNAL:
385 aux = "external";
386 break;
387 }
388
389 if (aux != NULL)
390 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE,
391 aux) == 0);
392
393 if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
394 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
395 vd->vdev_orig_guid) == 0);
396 }
397 }
398
399 return (nv);
400 }
401
402 /*
403 * Generate a view of the top-level vdevs. If we currently have holes
404 * in the namespace, then generate an array which contains a list of holey
405 * vdevs. Additionally, add the number of top-level children that currently
406 * exist.
407 */
408 void
409 vdev_top_config_generate(spa_t *spa, nvlist_t *config)
410 {
411 vdev_t *rvd = spa->spa_root_vdev;
412 uint64_t *array;
413 uint_t c, idx;
414
415 array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP);
416
417 for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
418 vdev_t *tvd = rvd->vdev_child[c];
419
420 if (tvd->vdev_ishole)
421 array[idx++] = c;
422 }
423
424 if (idx) {
425 VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
426 array, idx) == 0);
427 }
428
429 VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
430 rvd->vdev_children) == 0);
431
432 kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
433 }
434
435 /*
436 * Returns the configuration from the label of the given vdev. If 'label' is
437 * VDEV_BEST_LABEL, each label of the vdev will be read until a valid
438 * configuration is found; otherwise, only the specified label will be read.
439 */
440 nvlist_t *
441 vdev_label_read_config(vdev_t *vd, int label)
442 {
443 spa_t *spa = vd->vdev_spa;
444 nvlist_t *config = NULL;
445 vdev_phys_t *vp;
446 zio_t *zio;
447 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
448 ZIO_FLAG_SPECULATIVE;
449
450 ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
451
452 if (!vdev_readable(vd))
453 return (NULL);
454
455 vp = zio_buf_alloc(sizeof (vdev_phys_t));
456
457 retry:
458 for (int l = 0; l < VDEV_LABELS; l++) {
459 if (label >= 0 && label < VDEV_LABELS && label != l)
460 continue;
461
462 zio = zio_root(spa, NULL, NULL, flags);
463
464 vdev_label_read(zio, vd, l, vp,
465 offsetof(vdev_label_t, vl_vdev_phys),
466 sizeof (vdev_phys_t), NULL, NULL, flags);
467
468 if (zio_wait(zio) == 0 &&
469 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
470 &config, 0) == 0)
471 break;
472
473 if (config != NULL) {
474 nvlist_free(config);
475 config = NULL;
476 }
477 }
478
479 if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
480 flags |= ZIO_FLAG_TRYHARD;
481 goto retry;
482 }
483
484 zio_buf_free(vp, sizeof (vdev_phys_t));
485
486 return (config);
487 }
488
489 /*
490 * Determine if a device is in use. The 'spare_guid' parameter will be filled
491 * in with the device guid if this spare is active elsewhere on the system.
492 */
493 static boolean_t
494 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
495 uint64_t *spare_guid, uint64_t *l2cache_guid)
496 {
497 spa_t *spa = vd->vdev_spa;
498 uint64_t state, pool_guid, device_guid, txg, spare_pool;
499 uint64_t vdtxg = 0;
500 nvlist_t *label;
501
502 if (spare_guid)
503 *spare_guid = 0ULL;
504 if (l2cache_guid)
505 *l2cache_guid = 0ULL;
506
507 /*
508 * Read the label, if any, and perform some basic sanity checks.
509 */
510 if ((label = vdev_label_read_config(vd, VDEV_BEST_LABEL)) == NULL)
511 return (B_FALSE);
512
513 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
514 &vdtxg);
515
516 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
517 &state) != 0 ||
518 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
519 &device_guid) != 0) {
520 nvlist_free(label);
521 return (B_FALSE);
522 }
523
524 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
525 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
526 &pool_guid) != 0 ||
527 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
528 &txg) != 0)) {
529 nvlist_free(label);
530 return (B_FALSE);
531 }
532
533 nvlist_free(label);
534
535 /*
536 * Check to see if this device indeed belongs to the pool it claims to
537 * be a part of. The only way this is allowed is if the device is a hot
538 * spare (which we check for later on).
539 */
540 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
541 !spa_guid_exists(pool_guid, device_guid) &&
542 !spa_spare_exists(device_guid, NULL, NULL) &&
543 !spa_l2cache_exists(device_guid, NULL))
544 return (B_FALSE);
545
546 /*
547 * If the transaction group is zero, then this an initialized (but
548 * unused) label. This is only an error if the create transaction
549 * on-disk is the same as the one we're using now, in which case the
550 * user has attempted to add the same vdev multiple times in the same
551 * transaction.
552 */
553 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
554 txg == 0 && vdtxg == crtxg)
555 return (B_TRUE);
556
557 /*
558 * Check to see if this is a spare device. We do an explicit check for
559 * spa_has_spare() here because it may be on our pending list of spares
560 * to add. We also check if it is an l2cache device.
561 */
562 if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
563 spa_has_spare(spa, device_guid)) {
564 if (spare_guid)
565 *spare_guid = device_guid;
566
567 switch (reason) {
568 case VDEV_LABEL_CREATE:
569 case VDEV_LABEL_L2CACHE:
570 return (B_TRUE);
571
572 case VDEV_LABEL_REPLACE:
573 return (!spa_has_spare(spa, device_guid) ||
574 spare_pool != 0ULL);
575
576 case VDEV_LABEL_SPARE:
577 return (spa_has_spare(spa, device_guid));
578 }
579 }
580
581 /*
582 * Check to see if this is an l2cache device.
583 */
584 if (spa_l2cache_exists(device_guid, NULL))
585 return (B_TRUE);
586
587 /*
588 * We can't rely on a pool's state if it's been imported
589 * read-only. Instead we look to see if the pools is marked
590 * read-only in the namespace and set the state to active.
591 */
592 if ((spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
593 spa_mode(spa) == FREAD)
594 state = POOL_STATE_ACTIVE;
595
596 /*
597 * If the device is marked ACTIVE, then this device is in use by another
598 * pool on the system.
599 */
600 return (state == POOL_STATE_ACTIVE);
601 }
602
603 /*
604 * Initialize a vdev label. We check to make sure each leaf device is not in
605 * use, and writable. We put down an initial label which we will later
606 * overwrite with a complete label. Note that it's important to do this
607 * sequentially, not in parallel, so that we catch cases of multiple use of the
608 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
609 * itself.
610 */
611 int
612 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
613 {
614 spa_t *spa = vd->vdev_spa;
615 nvlist_t *label;
616 vdev_phys_t *vp;
617 char *pad2;
618 uberblock_t *ub;
619 zio_t *zio;
620 char *buf;
621 size_t buflen;
622 int error;
623 uint64_t spare_guid, l2cache_guid;
624 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
625
626 ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
627
628 for (int c = 0; c < vd->vdev_children; c++)
629 if ((error = vdev_label_init(vd->vdev_child[c],
630 crtxg, reason)) != 0)
631 return (error);
632
633 /* Track the creation time for this vdev */
634 vd->vdev_crtxg = crtxg;
635
636 if (!vd->vdev_ops->vdev_op_leaf)
637 return (0);
638
639 /*
640 * Dead vdevs cannot be initialized.
641 */
642 if (vdev_is_dead(vd))
643 return (EIO);
644
645 /*
646 * Determine if the vdev is in use.
647 */
648 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
649 vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
650 return (EBUSY);
651
652 /*
653 * If this is a request to add or replace a spare or l2cache device
654 * that is in use elsewhere on the system, then we must update the
655 * guid (which was initialized to a random value) to reflect the
656 * actual GUID (which is shared between multiple pools).
657 */
658 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
659 spare_guid != 0ULL) {
660 uint64_t guid_delta = spare_guid - vd->vdev_guid;
661
662 vd->vdev_guid += guid_delta;
663
664 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
665 pvd->vdev_guid_sum += guid_delta;
666
667 /*
668 * If this is a replacement, then we want to fallthrough to the
669 * rest of the code. If we're adding a spare, then it's already
670 * labeled appropriately and we can just return.
671 */
672 if (reason == VDEV_LABEL_SPARE)
673 return (0);
674 ASSERT(reason == VDEV_LABEL_REPLACE ||
675 reason == VDEV_LABEL_SPLIT);
676 }
677
678 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
679 l2cache_guid != 0ULL) {
680 uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
681
682 vd->vdev_guid += guid_delta;
683
684 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
685 pvd->vdev_guid_sum += guid_delta;
686
687 /*
688 * If this is a replacement, then we want to fallthrough to the
689 * rest of the code. If we're adding an l2cache, then it's
690 * already labeled appropriately and we can just return.
691 */
692 if (reason == VDEV_LABEL_L2CACHE)
693 return (0);
694 ASSERT(reason == VDEV_LABEL_REPLACE);
695 }
696
697 /*
698 * Initialize its label.
699 */
700 vp = zio_buf_alloc(sizeof (vdev_phys_t));
701 bzero(vp, sizeof (vdev_phys_t));
702
703 /*
704 * Generate a label describing the pool and our top-level vdev.
705 * We mark it as being from txg 0 to indicate that it's not
706 * really part of an active pool just yet. The labels will
707 * be written again with a meaningful txg by spa_sync().
708 */
709 if (reason == VDEV_LABEL_SPARE ||
710 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
711 /*
712 * For inactive hot spares, we generate a special label that
713 * identifies as a mutually shared hot spare. We write the
714 * label if we are adding a hot spare, or if we are removing an
715 * active hot spare (in which case we want to revert the
716 * labels).
717 */
718 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
719
720 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
721 spa_version(spa)) == 0);
722 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
723 POOL_STATE_SPARE) == 0);
724 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
725 vd->vdev_guid) == 0);
726 } else if (reason == VDEV_LABEL_L2CACHE ||
727 (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
728 /*
729 * For level 2 ARC devices, add a special label.
730 */
731 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
732
733 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
734 spa_version(spa)) == 0);
735 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
736 POOL_STATE_L2CACHE) == 0);
737 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
738 vd->vdev_guid) == 0);
739 } else {
740 uint64_t txg = 0ULL;
741
742 if (reason == VDEV_LABEL_SPLIT)
743 txg = spa->spa_uberblock.ub_txg;
744 label = spa_config_generate(spa, vd, txg, B_FALSE);
745
746 /*
747 * Add our creation time. This allows us to detect multiple
748 * vdev uses as described above, and automatically expires if we
749 * fail.
750 */
751 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
752 crtxg) == 0);
753 }
754
755 buf = vp->vp_nvlist;
756 buflen = sizeof (vp->vp_nvlist);
757
758 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
759 if (error != 0) {
760 nvlist_free(label);
761 zio_buf_free(vp, sizeof (vdev_phys_t));
762 /* EFAULT means nvlist_pack ran out of room */
763 return (error == EFAULT ? ENAMETOOLONG : EINVAL);
764 }
765
766 /*
767 * Initialize uberblock template.
768 */
769 ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
770 bzero(ub, VDEV_UBERBLOCK_RING);
771 *ub = spa->spa_uberblock;
772 ub->ub_txg = 0;
773
774 /* Initialize the 2nd padding area. */
775 pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
776 bzero(pad2, VDEV_PAD_SIZE);
777
778 /*
779 * Write everything in parallel.
780 */
781 retry:
782 zio = zio_root(spa, NULL, NULL, flags);
783
784 for (int l = 0; l < VDEV_LABELS; l++) {
785
786 vdev_label_write(zio, vd, l, vp,
787 offsetof(vdev_label_t, vl_vdev_phys),
788 sizeof (vdev_phys_t), NULL, NULL, flags);
789
790 /*
791 * Skip the 1st padding area.
792 * Zero out the 2nd padding area where it might have
793 * left over data from previous filesystem format.
794 */
795 vdev_label_write(zio, vd, l, pad2,
796 offsetof(vdev_label_t, vl_pad2),
797 VDEV_PAD_SIZE, NULL, NULL, flags);
798
799 vdev_label_write(zio, vd, l, ub,
800 offsetof(vdev_label_t, vl_uberblock),
801 VDEV_UBERBLOCK_RING, NULL, NULL, flags);
802 }
803
804 error = zio_wait(zio);
805
806 if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
807 flags |= ZIO_FLAG_TRYHARD;
808 goto retry;
809 }
810
811 nvlist_free(label);
812 zio_buf_free(pad2, VDEV_PAD_SIZE);
813 zio_buf_free(ub, VDEV_UBERBLOCK_RING);
814 zio_buf_free(vp, sizeof (vdev_phys_t));
815
816 /*
817 * If this vdev hasn't been previously identified as a spare, then we
818 * mark it as such only if a) we are labeling it as a spare, or b) it
819 * exists as a spare elsewhere in the system. Do the same for
820 * level 2 ARC devices.
821 */
822 if (error == 0 && !vd->vdev_isspare &&
823 (reason == VDEV_LABEL_SPARE ||
824 spa_spare_exists(vd->vdev_guid, NULL, NULL)))
825 spa_spare_add(vd);
826
827 if (error == 0 && !vd->vdev_isl2cache &&
828 (reason == VDEV_LABEL_L2CACHE ||
829 spa_l2cache_exists(vd->vdev_guid, NULL)))
830 spa_l2cache_add(vd);
831
832 return (error);
833 }
834
835 /*
836 * ==========================================================================
837 * uberblock load/sync
838 * ==========================================================================
839 */
840
841 /*
842 * Consider the following situation: txg is safely synced to disk. We've
843 * written the first uberblock for txg + 1, and then we lose power. When we
844 * come back up, we fail to see the uberblock for txg + 1 because, say,
845 * it was on a mirrored device and the replica to which we wrote txg + 1
846 * is now offline. If we then make some changes and sync txg + 1, and then
847 * the missing replica comes back, then for a few seconds we'll have two
848 * conflicting uberblocks on disk with the same txg. The solution is simple:
849 * among uberblocks with equal txg, choose the one with the latest timestamp.
850 */
851 static int
852 vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
853 {
854 if (ub1->ub_txg < ub2->ub_txg)
855 return (-1);
856 if (ub1->ub_txg > ub2->ub_txg)
857 return (1);
858
859 if (ub1->ub_timestamp < ub2->ub_timestamp)
860 return (-1);
861 if (ub1->ub_timestamp > ub2->ub_timestamp)
862 return (1);
863
864 return (0);
865 }
866
867 struct ubl_cbdata {
868 uberblock_t *ubl_ubbest; /* Best uberblock */
869 vdev_t *ubl_vd; /* vdev associated with the above */
870 int ubl_label; /* Label associated with the above */
871 };
872
873 static void
874 vdev_uberblock_load_done(zio_t *zio)
875 {
876 vdev_t *vd = zio->io_vd;
877 spa_t *spa = zio->io_spa;
878 zio_t *rio = zio->io_private;
879 uberblock_t *ub = zio->io_data;
880 struct ubl_cbdata *cbp = rio->io_private;
881
882 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
883
884 if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
885 mutex_enter(&rio->io_lock);
886 if (ub->ub_txg <= spa->spa_load_max_txg &&
887 vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
888 /*
889 * Keep track of the vdev and label in which this
890 * uberblock was found. We will use this information
891 * later to obtain the config nvlist associated with
892 * this uberblock.
893 */
894 *cbp->ubl_ubbest = *ub;
895 cbp->ubl_vd = vd;
896 cbp->ubl_label = vdev_label_number(vd->vdev_psize,
897 zio->io_offset);
898 }
899 mutex_exit(&rio->io_lock);
900 }
901
902 zio_buf_free(zio->io_data, zio->io_size);
903 }
904
905 static void
906 vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
907 struct ubl_cbdata *cbp)
908 {
909 for (int c = 0; c < vd->vdev_children; c++)
910 vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp);
911
912 if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
913 for (int l = 0; l < VDEV_LABELS; l++) {
914 for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
915 vdev_label_read(zio, vd, l,
916 zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
917 VDEV_UBERBLOCK_OFFSET(vd, n),
918 VDEV_UBERBLOCK_SIZE(vd),
919 vdev_uberblock_load_done, zio, flags);
920 }
921 }
922 }
923 }
924
925 /*
926 * Reads the 'best' uberblock from disk along with its associated
927 * configuration. First, we read the uberblock array of each label of each
928 * vdev, keeping track of the uberblock with the highest txg in each array.
929 * Then, we read the configuration from the same label as the best uberblock.
930 */
931 void
932 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
933 {
934 int i;
935 zio_t *zio;
936 spa_t *spa = rvd->vdev_spa;
937 struct ubl_cbdata cb;
938 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
939 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
940
941 ASSERT(ub);
942 ASSERT(config);
943
944 bzero(ub, sizeof (uberblock_t));
945 *config = NULL;
946
947 cb.ubl_ubbest = ub;
948 cb.ubl_vd = NULL;
949
950 spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
951 zio = zio_root(spa, NULL, &cb, flags);
952 vdev_uberblock_load_impl(zio, rvd, flags, &cb);
953 (void) zio_wait(zio);
954 if (cb.ubl_vd != NULL) {
955 for (i = cb.ubl_label % 2; i < VDEV_LABELS; i += 2) {
956 *config = vdev_label_read_config(cb.ubl_vd, i);
957 if (*config != NULL)
958 break;
959 }
960 }
961 spa_config_exit(spa, SCL_ALL, FTAG);
962 }
963
964 /*
965 * On success, increment root zio's count of good writes.
966 * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
967 */
968 static void
969 vdev_uberblock_sync_done(zio_t *zio)
970 {
971 uint64_t *good_writes = zio->io_private;
972
973 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
974 atomic_add_64(good_writes, 1);
975 }
976
977 /*
978 * Write the uberblock to all labels of all leaves of the specified vdev.
979 */
980 static void
981 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
982 {
983 uberblock_t *ubbuf;
984 int n;
985
986 for (int c = 0; c < vd->vdev_children; c++)
987 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
988
989 if (!vd->vdev_ops->vdev_op_leaf)
990 return;
991
992 if (!vdev_writeable(vd))
993 return;
994
995 n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
996
997 ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
998 bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
999 *ubbuf = *ub;
1000
1001 for (int l = 0; l < VDEV_LABELS; l++)
1002 vdev_label_write(zio, vd, l, ubbuf,
1003 VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1004 vdev_uberblock_sync_done, zio->io_private,
1005 flags | ZIO_FLAG_DONT_PROPAGATE);
1006
1007 zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
1008 }
1009
1010 int
1011 vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
1012 {
1013 spa_t *spa = svd[0]->vdev_spa;
1014 zio_t *zio;
1015 uint64_t good_writes = 0;
1016
1017 zio = zio_root(spa, NULL, &good_writes, flags);
1018
1019 for (int v = 0; v < svdcount; v++)
1020 vdev_uberblock_sync(zio, ub, svd[v], flags);
1021
1022 (void) zio_wait(zio);
1023
1024 /*
1025 * Flush the uberblocks to disk. This ensures that the odd labels
1026 * are no longer needed (because the new uberblocks and the even
1027 * labels are safely on disk), so it is safe to overwrite them.
1028 */
1029 zio = zio_root(spa, NULL, NULL, flags);
1030
1031 for (int v = 0; v < svdcount; v++)
1032 zio_flush(zio, svd[v]);
1033
1034 (void) zio_wait(zio);
1035
1036 return (good_writes >= 1 ? 0 : EIO);
1037 }
1038
1039 /*
1040 * On success, increment the count of good writes for our top-level vdev.
1041 */
1042 static void
1043 vdev_label_sync_done(zio_t *zio)
1044 {
1045 uint64_t *good_writes = zio->io_private;
1046
1047 if (zio->io_error == 0)
1048 atomic_add_64(good_writes, 1);
1049 }
1050
1051 /*
1052 * If there weren't enough good writes, indicate failure to the parent.
1053 */
1054 static void
1055 vdev_label_sync_top_done(zio_t *zio)
1056 {
1057 uint64_t *good_writes = zio->io_private;
1058
1059 if (*good_writes == 0)
1060 zio->io_error = EIO;
1061
1062 kmem_free(good_writes, sizeof (uint64_t));
1063 }
1064
1065 /*
1066 * We ignore errors for log and cache devices, simply free the private data.
1067 */
1068 static void
1069 vdev_label_sync_ignore_done(zio_t *zio)
1070 {
1071 kmem_free(zio->io_private, sizeof (uint64_t));
1072 }
1073
1074 /*
1075 * Write all even or odd labels to all leaves of the specified vdev.
1076 */
1077 static void
1078 vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
1079 {
1080 nvlist_t *label;
1081 vdev_phys_t *vp;
1082 char *buf;
1083 size_t buflen;
1084
1085 for (int c = 0; c < vd->vdev_children; c++)
1086 vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
1087
1088 if (!vd->vdev_ops->vdev_op_leaf)
1089 return;
1090
1091 if (!vdev_writeable(vd))
1092 return;
1093
1094 /*
1095 * Generate a label describing the top-level config to which we belong.
1096 */
1097 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1098
1099 vp = zio_buf_alloc(sizeof (vdev_phys_t));
1100 bzero(vp, sizeof (vdev_phys_t));
1101
1102 buf = vp->vp_nvlist;
1103 buflen = sizeof (vp->vp_nvlist);
1104
1105 if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) {
1106 for (; l < VDEV_LABELS; l += 2) {
1107 vdev_label_write(zio, vd, l, vp,
1108 offsetof(vdev_label_t, vl_vdev_phys),
1109 sizeof (vdev_phys_t),
1110 vdev_label_sync_done, zio->io_private,
1111 flags | ZIO_FLAG_DONT_PROPAGATE);
1112 }
1113 }
1114
1115 zio_buf_free(vp, sizeof (vdev_phys_t));
1116 nvlist_free(label);
1117 }
1118
1119 int
1120 vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
1121 {
1122 list_t *dl = &spa->spa_config_dirty_list;
1123 vdev_t *vd;
1124 zio_t *zio;
1125 int error;
1126
1127 /*
1128 * Write the new labels to disk.
1129 */
1130 zio = zio_root(spa, NULL, NULL, flags);
1131
1132 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
1133 uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t),
1134 KM_SLEEP);
1135
1136 ASSERT(!vd->vdev_ishole);
1137
1138 zio_t *vio = zio_null(zio, spa, NULL,
1139 (vd->vdev_islog || vd->vdev_aux != NULL) ?
1140 vdev_label_sync_ignore_done : vdev_label_sync_top_done,
1141 good_writes, flags);
1142 vdev_label_sync(vio, vd, l, txg, flags);
1143 zio_nowait(vio);
1144 }
1145
1146 error = zio_wait(zio);
1147
1148 /*
1149 * Flush the new labels to disk.
1150 */
1151 zio = zio_root(spa, NULL, NULL, flags);
1152
1153 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
1154 zio_flush(zio, vd);
1155
1156 (void) zio_wait(zio);
1157
1158 return (error);
1159 }
1160
1161 /*
1162 * Sync the uberblock and any changes to the vdev configuration.
1163 *
1164 * The order of operations is carefully crafted to ensure that
1165 * if the system panics or loses power at any time, the state on disk
1166 * is still transactionally consistent. The in-line comments below
1167 * describe the failure semantics at each stage.
1168 *
1169 * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1170 * at any time, you can just call it again, and it will resume its work.
1171 */
1172 int
1173 vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg, boolean_t tryhard)
1174 {
1175 spa_t *spa = svd[0]->vdev_spa;
1176 uberblock_t *ub = &spa->spa_uberblock;
1177 vdev_t *vd;
1178 zio_t *zio;
1179 int error;
1180 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1181
1182 /*
1183 * Normally, we don't want to try too hard to write every label and
1184 * uberblock. If there is a flaky disk, we don't want the rest of the
1185 * sync process to block while we retry. But if we can't write a
1186 * single label out, we should retry with ZIO_FLAG_TRYHARD before
1187 * bailing out and declaring the pool faulted.
1188 */
1189 if (tryhard)
1190 flags |= ZIO_FLAG_TRYHARD;
1191
1192 ASSERT(ub->ub_txg <= txg);
1193
1194 /*
1195 * If this isn't a resync due to I/O errors,
1196 * and nothing changed in this transaction group,
1197 * and the vdev configuration hasn't changed,
1198 * then there's nothing to do.
1199 */
1200 if (ub->ub_txg < txg &&
1201 uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
1202 list_is_empty(&spa->spa_config_dirty_list))
1203 return (0);
1204
1205 if (txg > spa_freeze_txg(spa))
1206 return (0);
1207
1208 ASSERT(txg <= spa->spa_final_txg);
1209
1210 /*
1211 * Flush the write cache of every disk that's been written to
1212 * in this transaction group. This ensures that all blocks
1213 * written in this txg will be committed to stable storage
1214 * before any uberblock that references them.
1215 */
1216 zio = zio_root(spa, NULL, NULL, flags);
1217
1218 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
1219 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
1220 zio_flush(zio, vd);
1221
1222 (void) zio_wait(zio);
1223
1224 /*
1225 * Sync out the even labels (L0, L2) for every dirty vdev. If the
1226 * system dies in the middle of this process, that's OK: all of the
1227 * even labels that made it to disk will be newer than any uberblock,
1228 * and will therefore be considered invalid. The odd labels (L1, L3),
1229 * which have not yet been touched, will still be valid. We flush
1230 * the new labels to disk to ensure that all even-label updates
1231 * are committed to stable storage before the uberblock update.
1232 */
1233 if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
1234 return (error);
1235
1236 /*
1237 * Sync the uberblocks to all vdevs in svd[].
1238 * If the system dies in the middle of this step, there are two cases
1239 * to consider, and the on-disk state is consistent either way:
1240 *
1241 * (1) If none of the new uberblocks made it to disk, then the
1242 * previous uberblock will be the newest, and the odd labels
1243 * (which had not yet been touched) will be valid with respect
1244 * to that uberblock.
1245 *
1246 * (2) If one or more new uberblocks made it to disk, then they
1247 * will be the newest, and the even labels (which had all
1248 * been successfully committed) will be valid with respect
1249 * to the new uberblocks.
1250 */
1251 if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1252 return (error);
1253
1254 /*
1255 * Sync out odd labels for every dirty vdev. If the system dies
1256 * in the middle of this process, the even labels and the new
1257 * uberblocks will suffice to open the pool. The next time
1258 * the pool is opened, the first thing we'll do -- before any
1259 * user data is modified -- is mark every vdev dirty so that
1260 * all labels will be brought up to date. We flush the new labels
1261 * to disk to ensure that all odd-label updates are committed to
1262 * stable storage before the next transaction group begins.
1263 */
1264 return (vdev_label_sync_list(spa, 1, txg, flags));
1265 }