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, 2016 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/metaslab_impl.h>
147 #include <sys/zio.h>
148 #include <sys/dsl_scan.h>
149 #include <sys/abd.h>
150 #include <sys/fs/zfs.h>
151
152 /*
153 * Basic routines to read and write from a vdev label.
154 * Used throughout the rest of this file.
155 */
156 uint64_t
157 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
158 {
159 ASSERT(offset < sizeof (vdev_label_t));
160 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
161
162 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
163 0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
164 }
165
166 /*
167 * Returns back the vdev label associated with the passed in offset.
168 */
169 int
170 vdev_label_number(uint64_t psize, uint64_t offset)
171 {
172 int l;
173
174 if (offset >= psize - VDEV_LABEL_END_SIZE) {
175 offset -= psize - VDEV_LABEL_END_SIZE;
176 offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
177 }
178 l = offset / sizeof (vdev_label_t);
179 return (l < VDEV_LABELS ? l : -1);
180 }
181
182 static void
183 vdev_label_read(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
184 uint64_t size, zio_done_func_t *done, void *private, int flags)
185 {
186 ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
187 SCL_STATE_ALL);
188 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
189
190 zio_nowait(zio_read_phys(zio, vd,
191 vdev_label_offset(vd->vdev_psize, l, offset),
192 size, buf, ZIO_CHECKSUM_LABEL, done, private,
193 ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
194 }
195
196 static void
197 vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t offset,
198 uint64_t size, zio_done_func_t *done, void *private, int flags)
199 {
200 ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
201 (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
202 (SCL_CONFIG | SCL_STATE) &&
203 dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
204 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
205
206 zio_nowait(zio_write_phys(zio, vd,
207 vdev_label_offset(vd->vdev_psize, l, offset),
208 size, buf, ZIO_CHECKSUM_LABEL, done, private,
209 ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
210 }
211
212 /*
213 * Generate the nvlist representing this vdev's config.
214 */
215 nvlist_t *
216 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
217 vdev_config_flag_t flags)
218 {
219 nvlist_t *nv = NULL;
220 vdev_indirect_config_t *vic = &vd->vdev_indirect_config;
221
222 nv = fnvlist_alloc();
223
224 fnvlist_add_string(nv, ZPOOL_CONFIG_TYPE, vd->vdev_ops->vdev_op_type);
225 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
226 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id);
227 fnvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid);
228
229 if (vd->vdev_path != NULL)
230 fnvlist_add_string(nv, ZPOOL_CONFIG_PATH, vd->vdev_path);
231
232 if (vd->vdev_devid != NULL)
233 fnvlist_add_string(nv, ZPOOL_CONFIG_DEVID, vd->vdev_devid);
234
235 if (vd->vdev_physpath != NULL)
236 fnvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
237 vd->vdev_physpath);
238
239 if (vd->vdev_fru != NULL)
240 fnvlist_add_string(nv, ZPOOL_CONFIG_FRU, vd->vdev_fru);
241
242 if (vd->vdev_nparity != 0) {
243 ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
244 VDEV_TYPE_RAIDZ) == 0);
245
246 /*
247 * Make sure someone hasn't managed to sneak a fancy new vdev
248 * into a crufty old storage pool.
249 */
250 ASSERT(vd->vdev_nparity == 1 ||
251 (vd->vdev_nparity <= 2 &&
252 spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
253 (vd->vdev_nparity <= 3 &&
254 spa_version(spa) >= SPA_VERSION_RAIDZ3));
255
256 /*
257 * Note that we'll add the nparity tag even on storage pools
258 * that only support a single parity device -- older software
259 * will just ignore it.
260 */
261 fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vd->vdev_nparity);
262 }
263
264 if (vd->vdev_wholedisk != -1ULL)
265 fnvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
266 vd->vdev_wholedisk);
267
268 if (vd->vdev_not_present && !(flags & VDEV_CONFIG_MISSING))
269 fnvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1);
270
271 if (vd->vdev_isspare)
272 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1);
273
274 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
275 vd == vd->vdev_top) {
276 fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
277 vd->vdev_ms_array);
278 fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
279 vd->vdev_ms_shift);
280 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift);
281 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
282 vd->vdev_asize);
283 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, vd->vdev_islog);
284 if (vd->vdev_removing) {
285 fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
286 vd->vdev_removing);
287 }
288 }
289
290 if (vd->vdev_dtl_sm != NULL) {
291 fnvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
292 space_map_object(vd->vdev_dtl_sm));
293 }
294
295 if (vic->vic_mapping_object != 0) {
296 fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_OBJECT,
297 vic->vic_mapping_object);
298 }
299
300 if (vic->vic_births_object != 0) {
301 fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_BIRTHS,
302 vic->vic_births_object);
303 }
304
305 if (vic->vic_prev_indirect_vdev != UINT64_MAX) {
306 fnvlist_add_uint64(nv, ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
307 vic->vic_prev_indirect_vdev);
308 }
309
310 if (vd->vdev_crtxg)
311 fnvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG, vd->vdev_crtxg);
312
313 if (flags & VDEV_CONFIG_MOS) {
314 if (vd->vdev_leaf_zap != 0) {
315 ASSERT(vd->vdev_ops->vdev_op_leaf);
316 fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_LEAF_ZAP,
317 vd->vdev_leaf_zap);
318 }
319
320 if (vd->vdev_top_zap != 0) {
321 ASSERT(vd == vd->vdev_top);
322 fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_TOP_ZAP,
323 vd->vdev_top_zap);
324 }
325 }
326
327 if (getstats) {
328 vdev_stat_t vs;
329
330 vdev_get_stats(vd, &vs);
331 fnvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
332 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t));
333
334 /* provide either current or previous scan information */
335 pool_scan_stat_t ps;
336 if (spa_scan_get_stats(spa, &ps) == 0) {
337 fnvlist_add_uint64_array(nv,
338 ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
339 sizeof (pool_scan_stat_t) / sizeof (uint64_t));
340 }
341
342 pool_removal_stat_t prs;
343 if (spa_removal_get_stats(spa, &prs) == 0) {
344 fnvlist_add_uint64_array(nv,
345 ZPOOL_CONFIG_REMOVAL_STATS, (uint64_t *)&prs,
346 sizeof (prs) / sizeof (uint64_t));
347 }
348
349 /*
350 * Note: this can be called from open context
351 * (spa_get_stats()), so we need the rwlock to prevent
352 * the mapping from being changed by condensing.
353 */
354 rw_enter(&vd->vdev_indirect_rwlock, RW_READER);
355 if (vd->vdev_indirect_mapping != NULL) {
356 ASSERT(vd->vdev_indirect_births != NULL);
357 vdev_indirect_mapping_t *vim =
358 vd->vdev_indirect_mapping;
359 fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
360 vdev_indirect_mapping_size(vim));
361 }
362 rw_exit(&vd->vdev_indirect_rwlock);
363 if (vd->vdev_mg != NULL &&
364 vd->vdev_mg->mg_fragmentation != ZFS_FRAG_INVALID) {
365 /*
366 * Compute approximately how much memory would be used
367 * for the indirect mapping if this device were to
368 * be removed.
369 *
370 * Note: If the frag metric is invalid, then not
371 * enough metaslabs have been converted to have
372 * histograms.
373 */
374 uint64_t seg_count = 0;
375
376 /*
377 * There are the same number of allocated segments
378 * as free segments, so we will have at least one
379 * entry per free segment.
380 */
381 for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
382 seg_count += vd->vdev_mg->mg_histogram[i];
383 }
384
385 /*
386 * The maximum length of a mapping is SPA_MAXBLOCKSIZE,
387 * so we need at least one entry per SPA_MAXBLOCKSIZE
388 * of allocated data.
389 */
390 seg_count += vd->vdev_stat.vs_alloc / SPA_MAXBLOCKSIZE;
391
392 fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
393 seg_count *
394 sizeof (vdev_indirect_mapping_entry_phys_t));
395 }
396 }
397
398 if (!vd->vdev_ops->vdev_op_leaf) {
399 nvlist_t **child;
400 int c, idx;
401
402 ASSERT(!vd->vdev_ishole);
403
404 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
405 KM_SLEEP);
406
407 for (c = 0, idx = 0; c < vd->vdev_children; c++) {
408 vdev_t *cvd = vd->vdev_child[c];
409
410 /*
411 * If we're generating an nvlist of removing
412 * vdevs then skip over any device which is
413 * not being removed.
414 */
415 if ((flags & VDEV_CONFIG_REMOVING) &&
416 !cvd->vdev_removing)
417 continue;
418
419 child[idx++] = vdev_config_generate(spa, cvd,
420 getstats, flags);
421 }
422
423 if (idx) {
424 fnvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
425 child, idx);
426 }
427
428 for (c = 0; c < idx; c++)
429 nvlist_free(child[c]);
430
431 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
432
433 } else {
434 const char *aux = NULL;
435
436 if (vd->vdev_offline && !vd->vdev_tmpoffline)
437 fnvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE, B_TRUE);
438 if (vd->vdev_resilver_txg != 0)
439 fnvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
440 vd->vdev_resilver_txg);
441 if (vd->vdev_faulted)
442 fnvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, B_TRUE);
443 if (vd->vdev_degraded)
444 fnvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, B_TRUE);
445 if (vd->vdev_removed)
446 fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, B_TRUE);
447 if (vd->vdev_unspare)
448 fnvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, B_TRUE);
449 if (vd->vdev_ishole)
450 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE, B_TRUE);
451
452 switch (vd->vdev_stat.vs_aux) {
453 case VDEV_AUX_ERR_EXCEEDED:
454 aux = "err_exceeded";
455 break;
456
457 case VDEV_AUX_EXTERNAL:
458 aux = "external";
459 break;
460 }
461
462 if (aux != NULL)
463 fnvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE, aux);
464
465 if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
466 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
467 vd->vdev_orig_guid);
468 }
469 }
470
471 return (nv);
472 }
473
474 /*
475 * Generate a view of the top-level vdevs. If we currently have holes
476 * in the namespace, then generate an array which contains a list of holey
477 * vdevs. Additionally, add the number of top-level children that currently
478 * exist.
479 */
480 void
481 vdev_top_config_generate(spa_t *spa, nvlist_t *config)
482 {
483 vdev_t *rvd = spa->spa_root_vdev;
484 uint64_t *array;
485 uint_t c, idx;
486
487 array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP);
488
489 for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
490 vdev_t *tvd = rvd->vdev_child[c];
491
492 if (tvd->vdev_ishole) {
493 array[idx++] = c;
494 }
495 }
496
497 if (idx) {
498 VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
499 array, idx) == 0);
500 }
501
502 VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
503 rvd->vdev_children) == 0);
504
505 kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
506 }
507
508 /*
509 * Returns the configuration from the label of the given vdev. For vdevs
510 * which don't have a txg value stored on their label (i.e. spares/cache)
511 * or have not been completely initialized (txg = 0) just return
512 * the configuration from the first valid label we find. Otherwise,
513 * find the most up-to-date label that does not exceed the specified
514 * 'txg' value.
515 */
516 nvlist_t *
517 vdev_label_read_config(vdev_t *vd, uint64_t txg)
518 {
519 spa_t *spa = vd->vdev_spa;
520 nvlist_t *config = NULL;
521 vdev_phys_t *vp;
522 abd_t *vp_abd;
523 zio_t *zio;
524 uint64_t best_txg = 0;
525 int error = 0;
526 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
527 ZIO_FLAG_SPECULATIVE;
528
529 ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
530
531 if (!vdev_readable(vd))
532 return (NULL);
533
534 vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
535 vp = abd_to_buf(vp_abd);
536
537 retry:
538 for (int l = 0; l < VDEV_LABELS; l++) {
539 nvlist_t *label = NULL;
540
541 zio = zio_root(spa, NULL, NULL, flags);
542
543 vdev_label_read(zio, vd, l, vp_abd,
544 offsetof(vdev_label_t, vl_vdev_phys),
545 sizeof (vdev_phys_t), NULL, NULL, flags);
546
547 if (zio_wait(zio) == 0 &&
548 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
549 &label, 0) == 0) {
550 uint64_t label_txg = 0;
551
552 /*
553 * Auxiliary vdevs won't have txg values in their
554 * labels and newly added vdevs may not have been
555 * completely initialized so just return the
556 * configuration from the first valid label we
557 * encounter.
558 */
559 error = nvlist_lookup_uint64(label,
560 ZPOOL_CONFIG_POOL_TXG, &label_txg);
561 if ((error || label_txg == 0) && !config) {
562 config = label;
563 break;
564 } else if (label_txg <= txg && label_txg > best_txg) {
565 best_txg = label_txg;
566 nvlist_free(config);
567 config = fnvlist_dup(label);
568 }
569 }
570
571 if (label != NULL) {
572 nvlist_free(label);
573 label = NULL;
574 }
575 }
576
577 if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
578 flags |= ZIO_FLAG_TRYHARD;
579 goto retry;
580 }
581
582 abd_free(vp_abd);
583
584 return (config);
585 }
586
587 /*
588 * Determine if a device is in use. The 'spare_guid' parameter will be filled
589 * in with the device guid if this spare is active elsewhere on the system.
590 */
591 static boolean_t
592 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
593 uint64_t *spare_guid, uint64_t *l2cache_guid)
594 {
595 spa_t *spa = vd->vdev_spa;
596 uint64_t state, pool_guid, device_guid, txg, spare_pool;
597 uint64_t vdtxg = 0;
598 nvlist_t *label;
599
600 if (spare_guid)
601 *spare_guid = 0ULL;
602 if (l2cache_guid)
603 *l2cache_guid = 0ULL;
604
605 /*
606 * Read the label, if any, and perform some basic sanity checks.
607 */
608 if ((label = vdev_label_read_config(vd, -1ULL)) == NULL)
609 return (B_FALSE);
610
611 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
612 &vdtxg);
613
614 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
615 &state) != 0 ||
616 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
617 &device_guid) != 0) {
618 nvlist_free(label);
619 return (B_FALSE);
620 }
621
622 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
623 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
624 &pool_guid) != 0 ||
625 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
626 &txg) != 0)) {
627 nvlist_free(label);
628 return (B_FALSE);
629 }
630
631 nvlist_free(label);
632
633 /*
634 * Check to see if this device indeed belongs to the pool it claims to
635 * be a part of. The only way this is allowed is if the device is a hot
636 * spare (which we check for later on).
637 */
638 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
639 !spa_guid_exists(pool_guid, device_guid) &&
640 !spa_spare_exists(device_guid, NULL, NULL) &&
641 !spa_l2cache_exists(device_guid, NULL))
642 return (B_FALSE);
643
644 /*
645 * If the transaction group is zero, then this an initialized (but
646 * unused) label. This is only an error if the create transaction
647 * on-disk is the same as the one we're using now, in which case the
648 * user has attempted to add the same vdev multiple times in the same
649 * transaction.
650 */
651 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
652 txg == 0 && vdtxg == crtxg)
653 return (B_TRUE);
654
655 /*
656 * Check to see if this is a spare device. We do an explicit check for
657 * spa_has_spare() here because it may be on our pending list of spares
658 * to add. We also check if it is an l2cache device.
659 */
660 if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
661 spa_has_spare(spa, device_guid)) {
662 if (spare_guid)
663 *spare_guid = device_guid;
664
665 switch (reason) {
666 case VDEV_LABEL_CREATE:
667 case VDEV_LABEL_L2CACHE:
668 return (B_TRUE);
669
670 case VDEV_LABEL_REPLACE:
671 return (!spa_has_spare(spa, device_guid) ||
672 spare_pool != 0ULL);
673
674 case VDEV_LABEL_SPARE:
675 return (spa_has_spare(spa, device_guid));
676 }
677 }
678
679 /*
680 * Check to see if this is an l2cache device.
681 */
682 if (spa_l2cache_exists(device_guid, NULL))
683 return (B_TRUE);
684
685 /*
686 * We can't rely on a pool's state if it's been imported
687 * read-only. Instead we look to see if the pools is marked
688 * read-only in the namespace and set the state to active.
689 */
690 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
691 (spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
692 spa_mode(spa) == FREAD)
693 state = POOL_STATE_ACTIVE;
694
695 /*
696 * If the device is marked ACTIVE, then this device is in use by another
697 * pool on the system.
698 */
699 return (state == POOL_STATE_ACTIVE);
700 }
701
702 /*
703 * Initialize a vdev label. We check to make sure each leaf device is not in
704 * use, and writable. We put down an initial label which we will later
705 * overwrite with a complete label. Note that it's important to do this
706 * sequentially, not in parallel, so that we catch cases of multiple use of the
707 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
708 * itself.
709 */
710 int
711 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
712 {
713 spa_t *spa = vd->vdev_spa;
714 nvlist_t *label;
715 vdev_phys_t *vp;
716 abd_t *vp_abd;
717 abd_t *pad2;
718 uberblock_t *ub;
719 abd_t *ub_abd;
720 zio_t *zio;
721 char *buf;
722 size_t buflen;
723 int error;
724 uint64_t spare_guid, l2cache_guid;
725 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
726
727 ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
728
729 for (int c = 0; c < vd->vdev_children; c++)
730 if ((error = vdev_label_init(vd->vdev_child[c],
731 crtxg, reason)) != 0)
732 return (error);
733
734 /* Track the creation time for this vdev */
735 vd->vdev_crtxg = crtxg;
736
737 if (!vd->vdev_ops->vdev_op_leaf || !spa_writeable(spa))
738 return (0);
739
740 /*
741 * Dead vdevs cannot be initialized.
742 */
743 if (vdev_is_dead(vd))
744 return (SET_ERROR(EIO));
745
746 /*
747 * Determine if the vdev is in use.
748 */
749 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
750 vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
751 return (SET_ERROR(EBUSY));
752
753 /*
754 * If this is a request to add or replace a spare or l2cache device
755 * that is in use elsewhere on the system, then we must update the
756 * guid (which was initialized to a random value) to reflect the
757 * actual GUID (which is shared between multiple pools).
758 */
759 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
760 spare_guid != 0ULL) {
761 uint64_t guid_delta = spare_guid - vd->vdev_guid;
762
763 vd->vdev_guid += guid_delta;
764
765 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
766 pvd->vdev_guid_sum += guid_delta;
767
768 /*
769 * If this is a replacement, then we want to fallthrough to the
770 * rest of the code. If we're adding a spare, then it's already
771 * labeled appropriately and we can just return.
772 */
773 if (reason == VDEV_LABEL_SPARE)
774 return (0);
775 ASSERT(reason == VDEV_LABEL_REPLACE ||
776 reason == VDEV_LABEL_SPLIT);
777 }
778
779 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
780 l2cache_guid != 0ULL) {
781 uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
782
783 vd->vdev_guid += guid_delta;
784
785 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
786 pvd->vdev_guid_sum += guid_delta;
787
788 /*
789 * If this is a replacement, then we want to fallthrough to the
790 * rest of the code. If we're adding an l2cache, then it's
791 * already labeled appropriately and we can just return.
792 */
793 if (reason == VDEV_LABEL_L2CACHE)
794 return (0);
795 ASSERT(reason == VDEV_LABEL_REPLACE);
796 }
797
798 /*
799 * Initialize its label.
800 */
801 vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
802 abd_zero(vp_abd, sizeof (vdev_phys_t));
803 vp = abd_to_buf(vp_abd);
804
805 /*
806 * Generate a label describing the pool and our top-level vdev.
807 * We mark it as being from txg 0 to indicate that it's not
808 * really part of an active pool just yet. The labels will
809 * be written again with a meaningful txg by spa_sync().
810 */
811 if (reason == VDEV_LABEL_SPARE ||
812 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
813 /*
814 * For inactive hot spares, we generate a special label that
815 * identifies as a mutually shared hot spare. We write the
816 * label if we are adding a hot spare, or if we are removing an
817 * active hot spare (in which case we want to revert the
818 * labels).
819 */
820 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
821
822 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
823 spa_version(spa)) == 0);
824 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
825 POOL_STATE_SPARE) == 0);
826 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
827 vd->vdev_guid) == 0);
828 } else if (reason == VDEV_LABEL_L2CACHE ||
829 (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
830 /*
831 * For level 2 ARC devices, add a special label.
832 */
833 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
834
835 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
836 spa_version(spa)) == 0);
837 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
838 POOL_STATE_L2CACHE) == 0);
839 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
840 vd->vdev_guid) == 0);
841 } else {
842 uint64_t txg = 0ULL;
843
844 if (reason == VDEV_LABEL_SPLIT)
845 txg = spa->spa_uberblock.ub_txg;
846 label = spa_config_generate(spa, vd, txg, B_FALSE);
847
848 /*
849 * Add our creation time. This allows us to detect multiple
850 * vdev uses as described above, and automatically expires if we
851 * fail.
852 */
853 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
854 crtxg) == 0);
855 }
856
857 buf = vp->vp_nvlist;
858 buflen = sizeof (vp->vp_nvlist);
859
860 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
861 if (error != 0) {
862 nvlist_free(label);
863 abd_free(vp_abd);
864 /* EFAULT means nvlist_pack ran out of room */
865 return (error == EFAULT ? ENAMETOOLONG : EINVAL);
866 }
867
868 /*
869 * Initialize uberblock template.
870 */
871 ub_abd = abd_alloc_linear(VDEV_UBERBLOCK_RING, B_TRUE);
872 abd_zero(ub_abd, VDEV_UBERBLOCK_RING);
873 abd_copy_from_buf(ub_abd, &spa->spa_uberblock, sizeof (uberblock_t));
874 ub = abd_to_buf(ub_abd);
875 ub->ub_txg = 0;
876
877 /* Initialize the 2nd padding area. */
878 pad2 = abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE);
879 abd_zero(pad2, VDEV_PAD_SIZE);
880
881 /*
882 * Write everything in parallel.
883 */
884 retry:
885 zio = zio_root(spa, NULL, NULL, flags);
886
887 for (int l = 0; l < VDEV_LABELS; l++) {
888
889 vdev_label_write(zio, vd, l, vp_abd,
890 offsetof(vdev_label_t, vl_vdev_phys),
891 sizeof (vdev_phys_t), NULL, NULL, flags);
892
893 /*
894 * Skip the 1st padding area.
895 * Zero out the 2nd padding area where it might have
896 * left over data from previous filesystem format.
897 */
898 vdev_label_write(zio, vd, l, pad2,
899 offsetof(vdev_label_t, vl_pad2),
900 VDEV_PAD_SIZE, NULL, NULL, flags);
901
902 vdev_label_write(zio, vd, l, ub_abd,
903 offsetof(vdev_label_t, vl_uberblock),
904 VDEV_UBERBLOCK_RING, NULL, NULL, flags);
905 }
906
907 error = zio_wait(zio);
908
909 if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
910 flags |= ZIO_FLAG_TRYHARD;
911 goto retry;
912 }
913
914 nvlist_free(label);
915 abd_free(pad2);
916 abd_free(ub_abd);
917 abd_free(vp_abd);
918
919 /*
920 * If this vdev hasn't been previously identified as a spare, then we
921 * mark it as such only if a) we are labeling it as a spare, or b) it
922 * exists as a spare elsewhere in the system. Do the same for
923 * level 2 ARC devices.
924 */
925 if (error == 0 && !vd->vdev_isspare &&
926 (reason == VDEV_LABEL_SPARE ||
927 spa_spare_exists(vd->vdev_guid, NULL, NULL)))
928 spa_spare_add(vd);
929
930 if (error == 0 && !vd->vdev_isl2cache &&
931 (reason == VDEV_LABEL_L2CACHE ||
932 spa_l2cache_exists(vd->vdev_guid, NULL)))
933 spa_l2cache_add(vd);
934
935 return (error);
936 }
937
938 /*
939 * ==========================================================================
940 * uberblock load/sync
941 * ==========================================================================
942 */
943
944 /*
945 * Consider the following situation: txg is safely synced to disk. We've
946 * written the first uberblock for txg + 1, and then we lose power. When we
947 * come back up, we fail to see the uberblock for txg + 1 because, say,
948 * it was on a mirrored device and the replica to which we wrote txg + 1
949 * is now offline. If we then make some changes and sync txg + 1, and then
950 * the missing replica comes back, then for a few seconds we'll have two
951 * conflicting uberblocks on disk with the same txg. The solution is simple:
952 * among uberblocks with equal txg, choose the one with the latest timestamp.
953 */
954 static int
955 vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
956 {
957 if (ub1->ub_txg < ub2->ub_txg)
958 return (-1);
959 if (ub1->ub_txg > ub2->ub_txg)
960 return (1);
961
962 if (ub1->ub_timestamp < ub2->ub_timestamp)
963 return (-1);
964 if (ub1->ub_timestamp > ub2->ub_timestamp)
965 return (1);
966
967 return (0);
968 }
969
970 struct ubl_cbdata {
971 uberblock_t *ubl_ubbest; /* Best uberblock */
972 vdev_t *ubl_vd; /* vdev associated with the above */
973 };
974
975 static void
976 vdev_uberblock_load_done(zio_t *zio)
977 {
978 vdev_t *vd = zio->io_vd;
979 spa_t *spa = zio->io_spa;
980 zio_t *rio = zio->io_private;
981 uberblock_t *ub = abd_to_buf(zio->io_abd);
982 struct ubl_cbdata *cbp = rio->io_private;
983
984 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
985
986 if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
987 mutex_enter(&rio->io_lock);
988 if (ub->ub_txg <= spa->spa_load_max_txg &&
989 vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
990 /*
991 * Keep track of the vdev in which this uberblock
992 * was found. We will use this information later
993 * to obtain the config nvlist associated with
994 * this uberblock.
995 */
996 *cbp->ubl_ubbest = *ub;
997 cbp->ubl_vd = vd;
998 }
999 mutex_exit(&rio->io_lock);
1000 }
1001
1002 abd_free(zio->io_abd);
1003 }
1004
1005 static void
1006 vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
1007 struct ubl_cbdata *cbp)
1008 {
1009 for (int c = 0; c < vd->vdev_children; c++)
1010 vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp);
1011
1012 if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
1013 for (int l = 0; l < VDEV_LABELS; l++) {
1014 for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
1015 vdev_label_read(zio, vd, l,
1016 abd_alloc_linear(VDEV_UBERBLOCK_SIZE(vd),
1017 B_TRUE), VDEV_UBERBLOCK_OFFSET(vd, n),
1018 VDEV_UBERBLOCK_SIZE(vd),
1019 vdev_uberblock_load_done, zio, flags);
1020 }
1021 }
1022 }
1023 }
1024
1025 /*
1026 * Reads the 'best' uberblock from disk along with its associated
1027 * configuration. First, we read the uberblock array of each label of each
1028 * vdev, keeping track of the uberblock with the highest txg in each array.
1029 * Then, we read the configuration from the same vdev as the best uberblock.
1030 */
1031 void
1032 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
1033 {
1034 zio_t *zio;
1035 spa_t *spa = rvd->vdev_spa;
1036 struct ubl_cbdata cb;
1037 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
1038 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
1039
1040 ASSERT(ub);
1041 ASSERT(config);
1042
1043 bzero(ub, sizeof (uberblock_t));
1044 *config = NULL;
1045
1046 cb.ubl_ubbest = ub;
1047 cb.ubl_vd = NULL;
1048
1049 spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
1050 zio = zio_root(spa, NULL, &cb, flags);
1051 vdev_uberblock_load_impl(zio, rvd, flags, &cb);
1052 (void) zio_wait(zio);
1053
1054 /*
1055 * It's possible that the best uberblock was discovered on a label
1056 * that has a configuration which was written in a future txg.
1057 * Search all labels on this vdev to find the configuration that
1058 * matches the txg for our uberblock.
1059 */
1060 if (cb.ubl_vd != NULL) {
1061 vdev_dbgmsg(cb.ubl_vd, "best uberblock found for spa %s. "
1062 "txg %llu", spa->spa_name, (u_longlong_t)ub->ub_txg);
1063
1064 *config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg);
1065 if (*config == NULL && spa->spa_extreme_rewind) {
1066 vdev_dbgmsg(cb.ubl_vd, "failed to read label config. "
1067 "Trying again without txg restrictions.");
1068 *config = vdev_label_read_config(cb.ubl_vd, UINT64_MAX);
1069 }
1070 if (*config == NULL) {
1071 vdev_dbgmsg(cb.ubl_vd, "failed to read label config");
1072 }
1073 }
1074 spa_config_exit(spa, SCL_ALL, FTAG);
1075 }
1076
1077 /*
1078 * On success, increment root zio's count of good writes.
1079 * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
1080 */
1081 static void
1082 vdev_uberblock_sync_done(zio_t *zio)
1083 {
1084 uint64_t *good_writes = zio->io_private;
1085
1086 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
1087 atomic_inc_64(good_writes);
1088 }
1089
1090 /*
1091 * Write the uberblock to all labels of all leaves of the specified vdev.
1092 */
1093 static void
1094 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
1095 {
1096 for (uint64_t c = 0; c < vd->vdev_children; c++)
1097 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
1098
1099 if (!vd->vdev_ops->vdev_op_leaf)
1100 return;
1101
1102 if (!vdev_writeable(vd))
1103 return;
1104
1105 int n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
1106
1107 /* Copy the uberblock_t into the ABD */
1108 abd_t *ub_abd = abd_alloc_for_io(VDEV_UBERBLOCK_SIZE(vd), B_TRUE);
1109 abd_zero(ub_abd, VDEV_UBERBLOCK_SIZE(vd));
1110 abd_copy_from_buf(ub_abd, ub, sizeof (uberblock_t));
1111
1112 for (int l = 0; l < VDEV_LABELS; l++)
1113 vdev_label_write(zio, vd, l, ub_abd,
1114 VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1115 vdev_uberblock_sync_done, zio->io_private,
1116 flags | ZIO_FLAG_DONT_PROPAGATE);
1117
1118 abd_free(ub_abd);
1119 }
1120
1121 /* Sync the uberblocks to all vdevs in svd[] */
1122 int
1123 vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
1124 {
1125 spa_t *spa = svd[0]->vdev_spa;
1126 zio_t *zio;
1127 uint64_t good_writes = 0;
1128
1129 zio = zio_root(spa, NULL, &good_writes, flags);
1130
1131 for (int v = 0; v < svdcount; v++)
1132 vdev_uberblock_sync(zio, ub, svd[v], flags);
1133
1134 (void) zio_wait(zio);
1135
1136 /*
1137 * Flush the uberblocks to disk. This ensures that the odd labels
1138 * are no longer needed (because the new uberblocks and the even
1139 * labels are safely on disk), so it is safe to overwrite them.
1140 */
1141 zio = zio_root(spa, NULL, NULL, flags);
1142
1143 for (int v = 0; v < svdcount; v++) {
1144 if (vdev_writeable(svd[v])) {
1145 zio_flush(zio, svd[v]);
1146 }
1147 }
1148
1149 (void) zio_wait(zio);
1150
1151 return (good_writes >= 1 ? 0 : EIO);
1152 }
1153
1154 /*
1155 * On success, increment the count of good writes for our top-level vdev.
1156 */
1157 static void
1158 vdev_label_sync_done(zio_t *zio)
1159 {
1160 uint64_t *good_writes = zio->io_private;
1161
1162 if (zio->io_error == 0)
1163 atomic_inc_64(good_writes);
1164 }
1165
1166 /*
1167 * If there weren't enough good writes, indicate failure to the parent.
1168 */
1169 static void
1170 vdev_label_sync_top_done(zio_t *zio)
1171 {
1172 uint64_t *good_writes = zio->io_private;
1173
1174 if (*good_writes == 0)
1175 zio->io_error = SET_ERROR(EIO);
1176
1177 kmem_free(good_writes, sizeof (uint64_t));
1178 }
1179
1180 /*
1181 * We ignore errors for log and cache devices, simply free the private data.
1182 */
1183 static void
1184 vdev_label_sync_ignore_done(zio_t *zio)
1185 {
1186 kmem_free(zio->io_private, sizeof (uint64_t));
1187 }
1188
1189 /*
1190 * Write all even or odd labels to all leaves of the specified vdev.
1191 */
1192 static void
1193 vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
1194 {
1195 nvlist_t *label;
1196 vdev_phys_t *vp;
1197 abd_t *vp_abd;
1198 char *buf;
1199 size_t buflen;
1200
1201 for (int c = 0; c < vd->vdev_children; c++)
1202 vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
1203
1204 if (!vd->vdev_ops->vdev_op_leaf)
1205 return;
1206
1207 if (!vdev_writeable(vd))
1208 return;
1209
1210 /*
1211 * Generate a label describing the top-level config to which we belong.
1212 */
1213 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1214
1215 vp_abd = abd_alloc_linear(sizeof (vdev_phys_t), B_TRUE);
1216 abd_zero(vp_abd, sizeof (vdev_phys_t));
1217 vp = abd_to_buf(vp_abd);
1218
1219 buf = vp->vp_nvlist;
1220 buflen = sizeof (vp->vp_nvlist);
1221
1222 if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) {
1223 for (; l < VDEV_LABELS; l += 2) {
1224 vdev_label_write(zio, vd, l, vp_abd,
1225 offsetof(vdev_label_t, vl_vdev_phys),
1226 sizeof (vdev_phys_t),
1227 vdev_label_sync_done, zio->io_private,
1228 flags | ZIO_FLAG_DONT_PROPAGATE);
1229 }
1230 }
1231
1232 abd_free(vp_abd);
1233 nvlist_free(label);
1234 }
1235
1236 int
1237 vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
1238 {
1239 list_t *dl = &spa->spa_config_dirty_list;
1240 vdev_t *vd;
1241 zio_t *zio;
1242 int error;
1243
1244 /*
1245 * Write the new labels to disk.
1246 */
1247 zio = zio_root(spa, NULL, NULL, flags);
1248
1249 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
1250 uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t),
1251 KM_SLEEP);
1252
1253 ASSERT(!vd->vdev_ishole);
1254
1255 zio_t *vio = zio_null(zio, spa, NULL,
1256 (vd->vdev_islog || vd->vdev_aux != NULL) ?
1257 vdev_label_sync_ignore_done : vdev_label_sync_top_done,
1258 good_writes, flags);
1259 vdev_label_sync(vio, vd, l, txg, flags);
1260 zio_nowait(vio);
1261 }
1262
1263 error = zio_wait(zio);
1264
1265 /*
1266 * Flush the new labels to disk.
1267 */
1268 zio = zio_root(spa, NULL, NULL, flags);
1269
1270 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
1271 zio_flush(zio, vd);
1272
1273 (void) zio_wait(zio);
1274
1275 return (error);
1276 }
1277
1278 /*
1279 * Sync the uberblock and any changes to the vdev configuration.
1280 *
1281 * The order of operations is carefully crafted to ensure that
1282 * if the system panics or loses power at any time, the state on disk
1283 * is still transactionally consistent. The in-line comments below
1284 * describe the failure semantics at each stage.
1285 *
1286 * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1287 * at any time, you can just call it again, and it will resume its work.
1288 */
1289 int
1290 vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg)
1291 {
1292 spa_t *spa = svd[0]->vdev_spa;
1293 uberblock_t *ub = &spa->spa_uberblock;
1294 vdev_t *vd;
1295 zio_t *zio;
1296 int error = 0;
1297 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1298
1299 retry:
1300 /*
1301 * Normally, we don't want to try too hard to write every label and
1302 * uberblock. If there is a flaky disk, we don't want the rest of the
1303 * sync process to block while we retry. But if we can't write a
1304 * single label out, we should retry with ZIO_FLAG_TRYHARD before
1305 * bailing out and declaring the pool faulted.
1306 */
1307 if (error != 0) {
1308 if ((flags & ZIO_FLAG_TRYHARD) != 0)
1309 return (error);
1310 flags |= ZIO_FLAG_TRYHARD;
1311 }
1312
1313 ASSERT(ub->ub_txg <= txg);
1314
1315 /*
1316 * If this isn't a resync due to I/O errors,
1317 * and nothing changed in this transaction group,
1318 * and the vdev configuration hasn't changed,
1319 * then there's nothing to do.
1320 */
1321 if (ub->ub_txg < txg &&
1322 uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
1323 list_is_empty(&spa->spa_config_dirty_list))
1324 return (0);
1325
1326 if (txg > spa_freeze_txg(spa))
1327 return (0);
1328
1329 ASSERT(txg <= spa->spa_final_txg);
1330
1331 /*
1332 * Flush the write cache of every disk that's been written to
1333 * in this transaction group. This ensures that all blocks
1334 * written in this txg will be committed to stable storage
1335 * before any uberblock that references them.
1336 */
1337 zio = zio_root(spa, NULL, NULL, flags);
1338
1339 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
1340 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
1341 zio_flush(zio, vd);
1342
1343 (void) zio_wait(zio);
1344
1345 /*
1346 * Sync out the even labels (L0, L2) for every dirty vdev. If the
1347 * system dies in the middle of this process, that's OK: all of the
1348 * even labels that made it to disk will be newer than any uberblock,
1349 * and will therefore be considered invalid. The odd labels (L1, L3),
1350 * which have not yet been touched, will still be valid. We flush
1351 * the new labels to disk to ensure that all even-label updates
1352 * are committed to stable storage before the uberblock update.
1353 */
1354 if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
1355 goto retry;
1356
1357 /*
1358 * Sync the uberblocks to all vdevs in svd[].
1359 * If the system dies in the middle of this step, there are two cases
1360 * to consider, and the on-disk state is consistent either way:
1361 *
1362 * (1) If none of the new uberblocks made it to disk, then the
1363 * previous uberblock will be the newest, and the odd labels
1364 * (which had not yet been touched) will be valid with respect
1365 * to that uberblock.
1366 *
1367 * (2) If one or more new uberblocks made it to disk, then they
1368 * will be the newest, and the even labels (which had all
1369 * been successfully committed) will be valid with respect
1370 * to the new uberblocks.
1371 */
1372 if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1373 goto retry;
1374
1375 /*
1376 * Sync out odd labels for every dirty vdev. If the system dies
1377 * in the middle of this process, the even labels and the new
1378 * uberblocks will suffice to open the pool. The next time
1379 * the pool is opened, the first thing we'll do -- before any
1380 * user data is modified -- is mark every vdev dirty so that
1381 * all labels will be brought up to date. We flush the new labels
1382 * to disk to ensure that all odd-label updates are committed to
1383 * stable storage before the next transaction group begins.
1384 */
1385 if ((error = vdev_label_sync_list(spa, 1, txg, flags)) != 0)
1386 goto retry;
1387
1388 return (0);
1389 }