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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/*
428870ff 22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
34dc7c2f
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23 */
24
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25/*
26 * Virtual Device Labels
27 * ---------------------
28 *
29 * The vdev label serves several distinct purposes:
30 *
31 * 1. Uniquely identify this device as part of a ZFS pool and confirm its
32 * identity within the pool.
33 *
34 * 2. Verify that all the devices given in a configuration are present
35 * within the pool.
36 *
37 * 3. Determine the uberblock for the pool.
38 *
39 * 4. In case of an import operation, determine the configuration of the
40 * toplevel vdev of which it is a part.
41 *
42 * 5. If an import operation cannot find all the devices in the pool,
43 * provide enough information to the administrator to determine which
44 * devices are missing.
45 *
46 * It is important to note that while the kernel is responsible for writing the
47 * label, it only consumes the information in the first three cases. The
48 * latter information is only consumed in userland when determining the
49 * configuration to import a pool.
50 *
51 *
52 * Label Organization
53 * ------------------
54 *
55 * Before describing the contents of the label, it's important to understand how
56 * the labels are written and updated with respect to the uberblock.
57 *
58 * When the pool configuration is altered, either because it was newly created
59 * or a device was added, we want to update all the labels such that we can deal
60 * with fatal failure at any point. To this end, each disk has two labels which
61 * are updated before and after the uberblock is synced. Assuming we have
62 * labels and an uberblock with the following transaction groups:
63 *
64 * L1 UB L2
65 * +------+ +------+ +------+
66 * | | | | | |
67 * | t10 | | t10 | | t10 |
68 * | | | | | |
69 * +------+ +------+ +------+
70 *
71 * In this stable state, the labels and the uberblock were all updated within
72 * the same transaction group (10). Each label is mirrored and checksummed, so
73 * that we can detect when we fail partway through writing the label.
74 *
75 * In order to identify which labels are valid, the labels are written in the
76 * following manner:
77 *
78 * 1. For each vdev, update 'L1' to the new label
79 * 2. Update the uberblock
80 * 3. For each vdev, update 'L2' to the new label
81 *
82 * Given arbitrary failure, we can determine the correct label to use based on
83 * the transaction group. If we fail after updating L1 but before updating the
84 * UB, we will notice that L1's transaction group is greater than the uberblock,
85 * so L2 must be valid. If we fail after writing the uberblock but before
86 * writing L2, we will notice that L2's transaction group is less than L1, and
87 * therefore L1 is valid.
88 *
89 * Another added complexity is that not every label is updated when the config
90 * is synced. If we add a single device, we do not want to have to re-write
91 * every label for every device in the pool. This means that both L1 and L2 may
92 * be older than the pool uberblock, because the necessary information is stored
93 * on another vdev.
94 *
95 *
96 * On-disk Format
97 * --------------
98 *
99 * The vdev label consists of two distinct parts, and is wrapped within the
100 * vdev_label_t structure. The label includes 8k of padding to permit legacy
101 * VTOC disk labels, but is otherwise ignored.
102 *
103 * The first half of the label is a packed nvlist which contains pool wide
104 * properties, per-vdev properties, and configuration information. It is
105 * described in more detail below.
106 *
107 * The latter half of the label consists of a redundant array of uberblocks.
108 * These uberblocks are updated whenever a transaction group is committed,
109 * or when the configuration is updated. When a pool is loaded, we scan each
110 * vdev for the 'best' uberblock.
111 *
112 *
113 * Configuration Information
114 * -------------------------
115 *
116 * The nvlist describing the pool and vdev contains the following elements:
117 *
118 * version ZFS on-disk version
119 * name Pool name
120 * state Pool state
121 * txg Transaction group in which this label was written
122 * pool_guid Unique identifier for this pool
123 * vdev_tree An nvlist describing vdev tree.
124 *
125 * Each leaf device label also contains the following:
126 *
127 * top_guid Unique ID for top-level vdev in which this is contained
128 * guid Unique ID for the leaf vdev
129 *
130 * The 'vs' configuration follows the format described in 'spa_config.c'.
131 */
132
133#include <sys/zfs_context.h>
134#include <sys/spa.h>
135#include <sys/spa_impl.h>
136#include <sys/dmu.h>
137#include <sys/zap.h>
138#include <sys/vdev.h>
139#include <sys/vdev_impl.h>
140#include <sys/uberblock_impl.h>
141#include <sys/metaslab.h>
142#include <sys/zio.h>
428870ff 143#include <sys/dsl_scan.h>
34dc7c2f
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144#include <sys/fs/zfs.h>
145
146/*
147 * Basic routines to read and write from a vdev label.
148 * Used throughout the rest of this file.
149 */
150uint64_t
151vdev_label_offset(uint64_t psize, int l, uint64_t offset)
152{
153 ASSERT(offset < sizeof (vdev_label_t));
154 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
155
156 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
157 0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
158}
159
b128c09f
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160/*
161 * Returns back the vdev label associated with the passed in offset.
162 */
163int
164vdev_label_number(uint64_t psize, uint64_t offset)
165{
166 int l;
167
168 if (offset >= psize - VDEV_LABEL_END_SIZE) {
169 offset -= psize - VDEV_LABEL_END_SIZE;
170 offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
171 }
172 l = offset / sizeof (vdev_label_t);
173 return (l < VDEV_LABELS ? l : -1);
174}
175
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176static void
177vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
b128c09f 178 uint64_t size, zio_done_func_t *done, void *private, int flags)
34dc7c2f 179{
b128c09f
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180 ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
181 SCL_STATE_ALL);
182 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
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183
184 zio_nowait(zio_read_phys(zio, vd,
185 vdev_label_offset(vd->vdev_psize, l, offset),
186 size, buf, ZIO_CHECKSUM_LABEL, done, private,
b128c09f 187 ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
34dc7c2f
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188}
189
190static void
191vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
192 uint64_t size, zio_done_func_t *done, void *private, int flags)
193{
b128c09f
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194 ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
195 (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
196 (SCL_CONFIG | SCL_STATE) &&
197 dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
198 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
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199
200 zio_nowait(zio_write_phys(zio, vd,
201 vdev_label_offset(vd->vdev_psize, l, offset),
202 size, buf, ZIO_CHECKSUM_LABEL, done, private,
203 ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
204}
205
206/*
207 * Generate the nvlist representing this vdev's config.
208 */
209nvlist_t *
210vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
428870ff 211 vdev_config_flag_t flags)
34dc7c2f
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212{
213 nvlist_t *nv = NULL;
214
215 VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
216
217 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
218 vd->vdev_ops->vdev_op_type) == 0);
428870ff 219 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
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220 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id)
221 == 0);
222 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0);
223
224 if (vd->vdev_path != NULL)
225 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH,
226 vd->vdev_path) == 0);
227
228 if (vd->vdev_devid != NULL)
229 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID,
230 vd->vdev_devid) == 0);
231
232 if (vd->vdev_physpath != NULL)
233 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
234 vd->vdev_physpath) == 0);
235
9babb374
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236 if (vd->vdev_fru != NULL)
237 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_FRU,
238 vd->vdev_fru) == 0);
239
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240 if (vd->vdev_nparity != 0) {
241 ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
242 VDEV_TYPE_RAIDZ) == 0);
243
244 /*
245 * Make sure someone hasn't managed to sneak a fancy new vdev
246 * into a crufty old storage pool.
247 */
248 ASSERT(vd->vdev_nparity == 1 ||
45d1cae3
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249 (vd->vdev_nparity <= 2 &&
250 spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
251 (vd->vdev_nparity <= 3 &&
252 spa_version(spa) >= SPA_VERSION_RAIDZ3));
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253
254 /*
255 * Note that we'll add the nparity tag even on storage pools
256 * that only support a single parity device -- older software
257 * will just ignore it.
258 */
259 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY,
260 vd->vdev_nparity) == 0);
261 }
262
263 if (vd->vdev_wholedisk != -1ULL)
264 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
265 vd->vdev_wholedisk) == 0);
266
267 if (vd->vdev_not_present)
268 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0);
269
270 if (vd->vdev_isspare)
271 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0);
272
428870ff
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273 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
274 vd == vd->vdev_top) {
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275 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
276 vd->vdev_ms_array) == 0);
277 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
278 vd->vdev_ms_shift) == 0);
279 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT,
280 vd->vdev_ashift) == 0);
281 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
282 vd->vdev_asize) == 0);
283 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG,
284 vd->vdev_islog) == 0);
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285 if (vd->vdev_removing)
286 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
287 vd->vdev_removing) == 0);
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288 }
289
fb5f0bc8 290 if (vd->vdev_dtl_smo.smo_object != 0)
34dc7c2f 291 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
fb5f0bc8 292 vd->vdev_dtl_smo.smo_object) == 0);
34dc7c2f 293
428870ff
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294 if (vd->vdev_crtxg)
295 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
296 vd->vdev_crtxg) == 0);
297
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298 if (getstats) {
299 vdev_stat_t vs;
428870ff
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300 pool_scan_stat_t ps;
301
34dc7c2f 302 vdev_get_stats(vd, &vs);
428870ff 303 VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
34dc7c2f 304 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0);
428870ff
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305
306 /* provide either current or previous scan information */
307 if (spa_scan_get_stats(spa, &ps) == 0) {
308 VERIFY(nvlist_add_uint64_array(nv,
309 ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
310 sizeof (pool_scan_stat_t) / sizeof (uint64_t))
311 == 0);
312 }
34dc7c2f
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313 }
314
315 if (!vd->vdev_ops->vdev_op_leaf) {
316 nvlist_t **child;
428870ff
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317 int c, idx;
318
319 ASSERT(!vd->vdev_ishole);
34dc7c2f
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320
321 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
322 KM_SLEEP);
323
428870ff
BB
324 for (c = 0, idx = 0; c < vd->vdev_children; c++) {
325 vdev_t *cvd = vd->vdev_child[c];
34dc7c2f 326
428870ff
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327 /*
328 * If we're generating an nvlist of removing
329 * vdevs then skip over any device which is
330 * not being removed.
331 */
332 if ((flags & VDEV_CONFIG_REMOVING) &&
333 !cvd->vdev_removing)
334 continue;
34dc7c2f 335
428870ff
BB
336 child[idx++] = vdev_config_generate(spa, cvd,
337 getstats, flags);
338 }
339
340 if (idx) {
341 VERIFY(nvlist_add_nvlist_array(nv,
342 ZPOOL_CONFIG_CHILDREN, child, idx) == 0);
343 }
344
345 for (c = 0; c < idx; c++)
34dc7c2f
BB
346 nvlist_free(child[c]);
347
348 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
349
350 } else {
428870ff
BB
351 const char *aux = NULL;
352
34dc7c2f
BB
353 if (vd->vdev_offline && !vd->vdev_tmpoffline)
354 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE,
355 B_TRUE) == 0);
572e2857
BB
356 if (vd->vdev_resilvering)
357 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVERING,
358 B_TRUE) == 0);
34dc7c2f
BB
359 if (vd->vdev_faulted)
360 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED,
361 B_TRUE) == 0);
362 if (vd->vdev_degraded)
363 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED,
364 B_TRUE) == 0);
365 if (vd->vdev_removed)
366 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED,
367 B_TRUE) == 0);
368 if (vd->vdev_unspare)
369 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE,
370 B_TRUE) == 0);
428870ff
BB
371 if (vd->vdev_ishole)
372 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE,
373 B_TRUE) == 0);
374
375 switch (vd->vdev_stat.vs_aux) {
376 case VDEV_AUX_ERR_EXCEEDED:
377 aux = "err_exceeded";
378 break;
379
380 case VDEV_AUX_EXTERNAL:
381 aux = "external";
382 break;
383 }
384
385 if (aux != NULL)
386 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE,
387 aux) == 0);
388
389 if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
390 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
391 vd->vdev_orig_guid) == 0);
392 }
34dc7c2f
BB
393 }
394
395 return (nv);
396}
397
428870ff
BB
398/*
399 * Generate a view of the top-level vdevs. If we currently have holes
400 * in the namespace, then generate an array which contains a list of holey
401 * vdevs. Additionally, add the number of top-level children that currently
402 * exist.
403 */
404void
405vdev_top_config_generate(spa_t *spa, nvlist_t *config)
406{
407 vdev_t *rvd = spa->spa_root_vdev;
408 uint64_t *array;
409 uint_t c, idx;
410
411 array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP);
412
413 for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
414 vdev_t *tvd = rvd->vdev_child[c];
415
416 if (tvd->vdev_ishole)
417 array[idx++] = c;
418 }
419
420 if (idx) {
421 VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
422 array, idx) == 0);
423 }
424
425 VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
426 rvd->vdev_children) == 0);
427
428 kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
429}
430
34dc7c2f
BB
431nvlist_t *
432vdev_label_read_config(vdev_t *vd)
433{
434 spa_t *spa = vd->vdev_spa;
435 nvlist_t *config = NULL;
436 vdev_phys_t *vp;
437 zio_t *zio;
9babb374
BB
438 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
439 ZIO_FLAG_SPECULATIVE;
d6320ddb 440 int l;
34dc7c2f 441
b128c09f 442 ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
34dc7c2f
BB
443
444 if (!vdev_readable(vd))
445 return (NULL);
446
447 vp = zio_buf_alloc(sizeof (vdev_phys_t));
448
9babb374 449retry:
d6320ddb 450 for (l = 0; l < VDEV_LABELS; l++) {
34dc7c2f 451
b128c09f 452 zio = zio_root(spa, NULL, NULL, flags);
34dc7c2f
BB
453
454 vdev_label_read(zio, vd, l, vp,
455 offsetof(vdev_label_t, vl_vdev_phys),
b128c09f 456 sizeof (vdev_phys_t), NULL, NULL, flags);
34dc7c2f
BB
457
458 if (zio_wait(zio) == 0 &&
459 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
460 &config, 0) == 0)
461 break;
462
463 if (config != NULL) {
464 nvlist_free(config);
465 config = NULL;
466 }
467 }
468
9babb374
BB
469 if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
470 flags |= ZIO_FLAG_TRYHARD;
471 goto retry;
472 }
473
34dc7c2f
BB
474 zio_buf_free(vp, sizeof (vdev_phys_t));
475
476 return (config);
477}
478
479/*
480 * Determine if a device is in use. The 'spare_guid' parameter will be filled
481 * in with the device guid if this spare is active elsewhere on the system.
482 */
483static boolean_t
484vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
485 uint64_t *spare_guid, uint64_t *l2cache_guid)
486{
487 spa_t *spa = vd->vdev_spa;
488 uint64_t state, pool_guid, device_guid, txg, spare_pool;
489 uint64_t vdtxg = 0;
490 nvlist_t *label;
491
492 if (spare_guid)
493 *spare_guid = 0ULL;
494 if (l2cache_guid)
495 *l2cache_guid = 0ULL;
496
497 /*
498 * Read the label, if any, and perform some basic sanity checks.
499 */
500 if ((label = vdev_label_read_config(vd)) == NULL)
501 return (B_FALSE);
502
503 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
504 &vdtxg);
505
506 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
507 &state) != 0 ||
508 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
509 &device_guid) != 0) {
510 nvlist_free(label);
511 return (B_FALSE);
512 }
513
514 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
515 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
516 &pool_guid) != 0 ||
517 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
518 &txg) != 0)) {
519 nvlist_free(label);
520 return (B_FALSE);
521 }
522
523 nvlist_free(label);
524
525 /*
526 * Check to see if this device indeed belongs to the pool it claims to
527 * be a part of. The only way this is allowed is if the device is a hot
528 * spare (which we check for later on).
529 */
530 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
531 !spa_guid_exists(pool_guid, device_guid) &&
b128c09f 532 !spa_spare_exists(device_guid, NULL, NULL) &&
34dc7c2f
BB
533 !spa_l2cache_exists(device_guid, NULL))
534 return (B_FALSE);
535
536 /*
537 * If the transaction group is zero, then this an initialized (but
538 * unused) label. This is only an error if the create transaction
539 * on-disk is the same as the one we're using now, in which case the
540 * user has attempted to add the same vdev multiple times in the same
541 * transaction.
542 */
543 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
544 txg == 0 && vdtxg == crtxg)
545 return (B_TRUE);
546
547 /*
548 * Check to see if this is a spare device. We do an explicit check for
549 * spa_has_spare() here because it may be on our pending list of spares
550 * to add. We also check if it is an l2cache device.
551 */
b128c09f 552 if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
34dc7c2f
BB
553 spa_has_spare(spa, device_guid)) {
554 if (spare_guid)
555 *spare_guid = device_guid;
556
557 switch (reason) {
558 case VDEV_LABEL_CREATE:
559 case VDEV_LABEL_L2CACHE:
560 return (B_TRUE);
561
562 case VDEV_LABEL_REPLACE:
563 return (!spa_has_spare(spa, device_guid) ||
564 spare_pool != 0ULL);
565
566 case VDEV_LABEL_SPARE:
567 return (spa_has_spare(spa, device_guid));
e75c13c3
BB
568 default:
569 break;
34dc7c2f
BB
570 }
571 }
572
573 /*
574 * Check to see if this is an l2cache device.
575 */
576 if (spa_l2cache_exists(device_guid, NULL))
577 return (B_TRUE);
578
572e2857
BB
579 /*
580 * We can't rely on a pool's state if it's been imported
581 * read-only. Instead we look to see if the pools is marked
582 * read-only in the namespace and set the state to active.
583 */
584 if ((spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
585 spa_mode(spa) == FREAD)
586 state = POOL_STATE_ACTIVE;
587
34dc7c2f
BB
588 /*
589 * If the device is marked ACTIVE, then this device is in use by another
590 * pool on the system.
591 */
592 return (state == POOL_STATE_ACTIVE);
593}
594
595/*
596 * Initialize a vdev label. We check to make sure each leaf device is not in
597 * use, and writable. We put down an initial label which we will later
598 * overwrite with a complete label. Note that it's important to do this
599 * sequentially, not in parallel, so that we catch cases of multiple use of the
600 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
601 * itself.
602 */
603int
604vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
605{
606 spa_t *spa = vd->vdev_spa;
607 nvlist_t *label;
608 vdev_phys_t *vp;
9babb374 609 char *pad2;
34dc7c2f
BB
610 uberblock_t *ub;
611 zio_t *zio;
34dc7c2f
BB
612 char *buf;
613 size_t buflen;
614 int error;
615 uint64_t spare_guid, l2cache_guid;
b128c09f 616 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
d6320ddb
BB
617 int c, l;
618 vdev_t *pvd;
34dc7c2f 619
b128c09f 620 ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
34dc7c2f 621
d6320ddb 622 for (c = 0; c < vd->vdev_children; c++)
34dc7c2f
BB
623 if ((error = vdev_label_init(vd->vdev_child[c],
624 crtxg, reason)) != 0)
625 return (error);
626
428870ff
BB
627 /* Track the creation time for this vdev */
628 vd->vdev_crtxg = crtxg;
629
34dc7c2f
BB
630 if (!vd->vdev_ops->vdev_op_leaf)
631 return (0);
632
633 /*
634 * Dead vdevs cannot be initialized.
635 */
636 if (vdev_is_dead(vd))
637 return (EIO);
638
639 /*
640 * Determine if the vdev is in use.
641 */
428870ff 642 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
34dc7c2f
BB
643 vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
644 return (EBUSY);
645
34dc7c2f
BB
646 /*
647 * If this is a request to add or replace a spare or l2cache device
648 * that is in use elsewhere on the system, then we must update the
649 * guid (which was initialized to a random value) to reflect the
650 * actual GUID (which is shared between multiple pools).
651 */
652 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
653 spare_guid != 0ULL) {
b128c09f 654 uint64_t guid_delta = spare_guid - vd->vdev_guid;
34dc7c2f 655
b128c09f 656 vd->vdev_guid += guid_delta;
34dc7c2f 657
d6320ddb 658 for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
b128c09f 659 pvd->vdev_guid_sum += guid_delta;
34dc7c2f
BB
660
661 /*
662 * If this is a replacement, then we want to fallthrough to the
663 * rest of the code. If we're adding a spare, then it's already
664 * labeled appropriately and we can just return.
665 */
666 if (reason == VDEV_LABEL_SPARE)
667 return (0);
428870ff
BB
668 ASSERT(reason == VDEV_LABEL_REPLACE ||
669 reason == VDEV_LABEL_SPLIT);
34dc7c2f
BB
670 }
671
672 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
673 l2cache_guid != 0ULL) {
b128c09f 674 uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
34dc7c2f 675
b128c09f 676 vd->vdev_guid += guid_delta;
34dc7c2f 677
d6320ddb 678 for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
b128c09f 679 pvd->vdev_guid_sum += guid_delta;
34dc7c2f
BB
680
681 /*
682 * If this is a replacement, then we want to fallthrough to the
683 * rest of the code. If we're adding an l2cache, then it's
684 * already labeled appropriately and we can just return.
685 */
686 if (reason == VDEV_LABEL_L2CACHE)
687 return (0);
688 ASSERT(reason == VDEV_LABEL_REPLACE);
689 }
690
691 /*
692 * Initialize its label.
693 */
694 vp = zio_buf_alloc(sizeof (vdev_phys_t));
695 bzero(vp, sizeof (vdev_phys_t));
696
697 /*
698 * Generate a label describing the pool and our top-level vdev.
699 * We mark it as being from txg 0 to indicate that it's not
700 * really part of an active pool just yet. The labels will
701 * be written again with a meaningful txg by spa_sync().
702 */
703 if (reason == VDEV_LABEL_SPARE ||
704 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
705 /*
706 * For inactive hot spares, we generate a special label that
707 * identifies as a mutually shared hot spare. We write the
708 * label if we are adding a hot spare, or if we are removing an
709 * active hot spare (in which case we want to revert the
710 * labels).
711 */
712 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
713
714 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
715 spa_version(spa)) == 0);
716 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
717 POOL_STATE_SPARE) == 0);
718 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
719 vd->vdev_guid) == 0);
720 } else if (reason == VDEV_LABEL_L2CACHE ||
721 (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
722 /*
723 * For level 2 ARC devices, add a special label.
724 */
725 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
726
727 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
728 spa_version(spa)) == 0);
729 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
730 POOL_STATE_L2CACHE) == 0);
731 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
732 vd->vdev_guid) == 0);
733 } else {
428870ff
BB
734 uint64_t txg = 0ULL;
735
736 if (reason == VDEV_LABEL_SPLIT)
737 txg = spa->spa_uberblock.ub_txg;
738 label = spa_config_generate(spa, vd, txg, B_FALSE);
34dc7c2f
BB
739
740 /*
741 * Add our creation time. This allows us to detect multiple
742 * vdev uses as described above, and automatically expires if we
743 * fail.
744 */
745 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
746 crtxg) == 0);
747 }
748
749 buf = vp->vp_nvlist;
750 buflen = sizeof (vp->vp_nvlist);
751
752 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
753 if (error != 0) {
754 nvlist_free(label);
755 zio_buf_free(vp, sizeof (vdev_phys_t));
756 /* EFAULT means nvlist_pack ran out of room */
757 return (error == EFAULT ? ENAMETOOLONG : EINVAL);
758 }
759
34dc7c2f
BB
760 /*
761 * Initialize uberblock template.
762 */
45d1cae3
BB
763 ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
764 bzero(ub, VDEV_UBERBLOCK_RING);
34dc7c2f
BB
765 *ub = spa->spa_uberblock;
766 ub->ub_txg = 0;
767
9babb374
BB
768 /* Initialize the 2nd padding area. */
769 pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
770 bzero(pad2, VDEV_PAD_SIZE);
771
34dc7c2f
BB
772 /*
773 * Write everything in parallel.
774 */
9babb374 775retry:
34dc7c2f
BB
776 zio = zio_root(spa, NULL, NULL, flags);
777
d6320ddb 778 for (l = 0; l < VDEV_LABELS; l++) {
34dc7c2f
BB
779
780 vdev_label_write(zio, vd, l, vp,
781 offsetof(vdev_label_t, vl_vdev_phys),
782 sizeof (vdev_phys_t), NULL, NULL, flags);
783
9babb374
BB
784 /*
785 * Skip the 1st padding area.
786 * Zero out the 2nd padding area where it might have
787 * left over data from previous filesystem format.
788 */
789 vdev_label_write(zio, vd, l, pad2,
790 offsetof(vdev_label_t, vl_pad2),
791 VDEV_PAD_SIZE, NULL, NULL, flags);
34dc7c2f 792
45d1cae3
BB
793 vdev_label_write(zio, vd, l, ub,
794 offsetof(vdev_label_t, vl_uberblock),
795 VDEV_UBERBLOCK_RING, NULL, NULL, flags);
34dc7c2f
BB
796 }
797
798 error = zio_wait(zio);
799
9babb374
BB
800 if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
801 flags |= ZIO_FLAG_TRYHARD;
802 goto retry;
803 }
804
34dc7c2f 805 nvlist_free(label);
9babb374 806 zio_buf_free(pad2, VDEV_PAD_SIZE);
45d1cae3 807 zio_buf_free(ub, VDEV_UBERBLOCK_RING);
34dc7c2f
BB
808 zio_buf_free(vp, sizeof (vdev_phys_t));
809
810 /*
811 * If this vdev hasn't been previously identified as a spare, then we
812 * mark it as such only if a) we are labeling it as a spare, or b) it
813 * exists as a spare elsewhere in the system. Do the same for
814 * level 2 ARC devices.
815 */
816 if (error == 0 && !vd->vdev_isspare &&
817 (reason == VDEV_LABEL_SPARE ||
b128c09f 818 spa_spare_exists(vd->vdev_guid, NULL, NULL)))
34dc7c2f
BB
819 spa_spare_add(vd);
820
821 if (error == 0 && !vd->vdev_isl2cache &&
822 (reason == VDEV_LABEL_L2CACHE ||
823 spa_l2cache_exists(vd->vdev_guid, NULL)))
824 spa_l2cache_add(vd);
825
826 return (error);
827}
828
829/*
830 * ==========================================================================
831 * uberblock load/sync
832 * ==========================================================================
833 */
834
835/*
836 * Consider the following situation: txg is safely synced to disk. We've
837 * written the first uberblock for txg + 1, and then we lose power. When we
838 * come back up, we fail to see the uberblock for txg + 1 because, say,
839 * it was on a mirrored device and the replica to which we wrote txg + 1
840 * is now offline. If we then make some changes and sync txg + 1, and then
841 * the missing replica comes back, then for a new seconds we'll have two
842 * conflicting uberblocks on disk with the same txg. The solution is simple:
843 * among uberblocks with equal txg, choose the one with the latest timestamp.
844 */
845static int
846vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
847{
848 if (ub1->ub_txg < ub2->ub_txg)
849 return (-1);
850 if (ub1->ub_txg > ub2->ub_txg)
851 return (1);
852
853 if (ub1->ub_timestamp < ub2->ub_timestamp)
854 return (-1);
855 if (ub1->ub_timestamp > ub2->ub_timestamp)
856 return (1);
857
858 return (0);
859}
860
861static void
862vdev_uberblock_load_done(zio_t *zio)
863{
428870ff 864 spa_t *spa = zio->io_spa;
b128c09f 865 zio_t *rio = zio->io_private;
34dc7c2f 866 uberblock_t *ub = zio->io_data;
b128c09f 867 uberblock_t *ubbest = rio->io_private;
34dc7c2f
BB
868
869 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(zio->io_vd));
870
871 if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
b128c09f 872 mutex_enter(&rio->io_lock);
428870ff 873 if (ub->ub_txg <= spa->spa_load_max_txg &&
fb5f0bc8 874 vdev_uberblock_compare(ub, ubbest) > 0)
34dc7c2f 875 *ubbest = *ub;
b128c09f 876 mutex_exit(&rio->io_lock);
34dc7c2f
BB
877 }
878
879 zio_buf_free(zio->io_data, zio->io_size);
880}
881
882void
883vdev_uberblock_load(zio_t *zio, vdev_t *vd, uberblock_t *ubbest)
884{
b128c09f
BB
885 spa_t *spa = vd->vdev_spa;
886 vdev_t *rvd = spa->spa_root_vdev;
9babb374
BB
887 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
888 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
d6320ddb 889 int c, l, n;
b128c09f
BB
890
891 if (vd == rvd) {
892 ASSERT(zio == NULL);
893 spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
894 zio = zio_root(spa, NULL, ubbest, flags);
895 bzero(ubbest, sizeof (uberblock_t));
896 }
34dc7c2f 897
b128c09f 898 ASSERT(zio != NULL);
34dc7c2f 899
d6320ddb 900 for (c = 0; c < vd->vdev_children; c++)
b128c09f 901 vdev_uberblock_load(zio, vd->vdev_child[c], ubbest);
34dc7c2f 902
b128c09f 903 if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
d6320ddb
BB
904 for (l = 0; l < VDEV_LABELS; l++) {
905 for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
b128c09f
BB
906 vdev_label_read(zio, vd, l,
907 zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
908 VDEV_UBERBLOCK_OFFSET(vd, n),
909 VDEV_UBERBLOCK_SIZE(vd),
910 vdev_uberblock_load_done, zio, flags);
911 }
34dc7c2f
BB
912 }
913 }
b128c09f
BB
914
915 if (vd == rvd) {
916 (void) zio_wait(zio);
917 spa_config_exit(spa, SCL_ALL, FTAG);
918 }
34dc7c2f
BB
919}
920
921/*
922 * On success, increment root zio's count of good writes.
923 * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
924 */
925static void
926vdev_uberblock_sync_done(zio_t *zio)
927{
928 uint64_t *good_writes = zio->io_private;
929
930 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
931 atomic_add_64(good_writes, 1);
932}
933
934/*
935 * Write the uberblock to all labels of all leaves of the specified vdev.
936 */
937static void
b128c09f 938vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
34dc7c2f 939{
34dc7c2f 940 uberblock_t *ubbuf;
d6320ddb 941 int c, l, n;
34dc7c2f 942
d6320ddb 943 for (c = 0; c < vd->vdev_children; c++)
b128c09f 944 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
34dc7c2f
BB
945
946 if (!vd->vdev_ops->vdev_op_leaf)
947 return;
948
b128c09f 949 if (!vdev_writeable(vd))
34dc7c2f
BB
950 return;
951
952 n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
953
954 ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
955 bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
956 *ubbuf = *ub;
957
d6320ddb 958 for (l = 0; l < VDEV_LABELS; l++)
34dc7c2f 959 vdev_label_write(zio, vd, l, ubbuf,
b128c09f 960 VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
34dc7c2f 961 vdev_uberblock_sync_done, zio->io_private,
b128c09f 962 flags | ZIO_FLAG_DONT_PROPAGATE);
34dc7c2f
BB
963
964 zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
965}
966
967int
968vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
969{
970 spa_t *spa = svd[0]->vdev_spa;
34dc7c2f
BB
971 zio_t *zio;
972 uint64_t good_writes = 0;
d6320ddb 973 int v;
34dc7c2f
BB
974
975 zio = zio_root(spa, NULL, &good_writes, flags);
976
d6320ddb 977 for (v = 0; v < svdcount; v++)
b128c09f 978 vdev_uberblock_sync(zio, ub, svd[v], flags);
34dc7c2f
BB
979
980 (void) zio_wait(zio);
981
982 /*
983 * Flush the uberblocks to disk. This ensures that the odd labels
984 * are no longer needed (because the new uberblocks and the even
985 * labels are safely on disk), so it is safe to overwrite them.
986 */
987 zio = zio_root(spa, NULL, NULL, flags);
988
d6320ddb 989 for (v = 0; v < svdcount; v++)
34dc7c2f
BB
990 zio_flush(zio, svd[v]);
991
992 (void) zio_wait(zio);
993
994 return (good_writes >= 1 ? 0 : EIO);
995}
996
997/*
998 * On success, increment the count of good writes for our top-level vdev.
999 */
1000static void
1001vdev_label_sync_done(zio_t *zio)
1002{
1003 uint64_t *good_writes = zio->io_private;
1004
1005 if (zio->io_error == 0)
1006 atomic_add_64(good_writes, 1);
1007}
1008
1009/*
1010 * If there weren't enough good writes, indicate failure to the parent.
1011 */
1012static void
1013vdev_label_sync_top_done(zio_t *zio)
1014{
1015 uint64_t *good_writes = zio->io_private;
1016
1017 if (*good_writes == 0)
1018 zio->io_error = EIO;
1019
1020 kmem_free(good_writes, sizeof (uint64_t));
1021}
1022
b128c09f
BB
1023/*
1024 * We ignore errors for log and cache devices, simply free the private data.
1025 */
1026static void
1027vdev_label_sync_ignore_done(zio_t *zio)
1028{
1029 kmem_free(zio->io_private, sizeof (uint64_t));
1030}
1031
34dc7c2f
BB
1032/*
1033 * Write all even or odd labels to all leaves of the specified vdev.
1034 */
1035static void
b128c09f 1036vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
34dc7c2f
BB
1037{
1038 nvlist_t *label;
1039 vdev_phys_t *vp;
1040 char *buf;
1041 size_t buflen;
d6320ddb 1042 int c;
34dc7c2f 1043
d6320ddb 1044 for (c = 0; c < vd->vdev_children; c++)
b128c09f 1045 vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
34dc7c2f
BB
1046
1047 if (!vd->vdev_ops->vdev_op_leaf)
1048 return;
1049
b128c09f 1050 if (!vdev_writeable(vd))
34dc7c2f
BB
1051 return;
1052
1053 /*
1054 * Generate a label describing the top-level config to which we belong.
1055 */
1056 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1057
1058 vp = zio_buf_alloc(sizeof (vdev_phys_t));
1059 bzero(vp, sizeof (vdev_phys_t));
1060
1061 buf = vp->vp_nvlist;
1062 buflen = sizeof (vp->vp_nvlist);
1063
1064 if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) {
1065 for (; l < VDEV_LABELS; l += 2) {
1066 vdev_label_write(zio, vd, l, vp,
1067 offsetof(vdev_label_t, vl_vdev_phys),
1068 sizeof (vdev_phys_t),
1069 vdev_label_sync_done, zio->io_private,
b128c09f 1070 flags | ZIO_FLAG_DONT_PROPAGATE);
34dc7c2f
BB
1071 }
1072 }
1073
1074 zio_buf_free(vp, sizeof (vdev_phys_t));
1075 nvlist_free(label);
1076}
1077
1078int
b128c09f 1079vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
34dc7c2f 1080{
b128c09f 1081 list_t *dl = &spa->spa_config_dirty_list;
34dc7c2f
BB
1082 vdev_t *vd;
1083 zio_t *zio;
1084 int error;
1085
1086 /*
1087 * Write the new labels to disk.
1088 */
1089 zio = zio_root(spa, NULL, NULL, flags);
1090
1091 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
d6320ddb
BB
1092 uint64_t *good_writes;
1093 zio_t *vio;
428870ff
BB
1094
1095 ASSERT(!vd->vdev_ishole);
1096
d6320ddb
BB
1097 good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
1098 vio = zio_null(zio, spa, NULL,
b128c09f
BB
1099 (vd->vdev_islog || vd->vdev_aux != NULL) ?
1100 vdev_label_sync_ignore_done : vdev_label_sync_top_done,
34dc7c2f 1101 good_writes, flags);
b128c09f 1102 vdev_label_sync(vio, vd, l, txg, flags);
34dc7c2f
BB
1103 zio_nowait(vio);
1104 }
1105
1106 error = zio_wait(zio);
1107
1108 /*
1109 * Flush the new labels to disk.
1110 */
1111 zio = zio_root(spa, NULL, NULL, flags);
1112
1113 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
1114 zio_flush(zio, vd);
1115
1116 (void) zio_wait(zio);
1117
1118 return (error);
1119}
1120
1121/*
1122 * Sync the uberblock and any changes to the vdev configuration.
1123 *
1124 * The order of operations is carefully crafted to ensure that
1125 * if the system panics or loses power at any time, the state on disk
1126 * is still transactionally consistent. The in-line comments below
1127 * describe the failure semantics at each stage.
1128 *
1129 * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1130 * at any time, you can just call it again, and it will resume its work.
1131 */
1132int
9babb374 1133vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg, boolean_t tryhard)
34dc7c2f
BB
1134{
1135 spa_t *spa = svd[0]->vdev_spa;
1136 uberblock_t *ub = &spa->spa_uberblock;
1137 vdev_t *vd;
1138 zio_t *zio;
1139 int error;
b128c09f 1140 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
34dc7c2f 1141
9babb374
BB
1142 /*
1143 * Normally, we don't want to try too hard to write every label and
1144 * uberblock. If there is a flaky disk, we don't want the rest of the
1145 * sync process to block while we retry. But if we can't write a
1146 * single label out, we should retry with ZIO_FLAG_TRYHARD before
1147 * bailing out and declaring the pool faulted.
1148 */
1149 if (tryhard)
1150 flags |= ZIO_FLAG_TRYHARD;
1151
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BB
1152 ASSERT(ub->ub_txg <= txg);
1153
1154 /*
1155 * If this isn't a resync due to I/O errors,
1156 * and nothing changed in this transaction group,
1157 * and the vdev configuration hasn't changed,
1158 * then there's nothing to do.
1159 */
1160 if (ub->ub_txg < txg &&
1161 uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
b128c09f 1162 list_is_empty(&spa->spa_config_dirty_list))
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BB
1163 return (0);
1164
1165 if (txg > spa_freeze_txg(spa))
1166 return (0);
1167
1168 ASSERT(txg <= spa->spa_final_txg);
1169
1170 /*
1171 * Flush the write cache of every disk that's been written to
1172 * in this transaction group. This ensures that all blocks
1173 * written in this txg will be committed to stable storage
1174 * before any uberblock that references them.
1175 */
1176 zio = zio_root(spa, NULL, NULL, flags);
1177
1178 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
1179 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
1180 zio_flush(zio, vd);
1181
1182 (void) zio_wait(zio);
1183
1184 /*
1185 * Sync out the even labels (L0, L2) for every dirty vdev. If the
1186 * system dies in the middle of this process, that's OK: all of the
1187 * even labels that made it to disk will be newer than any uberblock,
1188 * and will therefore be considered invalid. The odd labels (L1, L3),
1189 * which have not yet been touched, will still be valid. We flush
1190 * the new labels to disk to ensure that all even-label updates
1191 * are committed to stable storage before the uberblock update.
1192 */
b128c09f 1193 if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
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1194 return (error);
1195
1196 /*
1197 * Sync the uberblocks to all vdevs in svd[].
1198 * If the system dies in the middle of this step, there are two cases
1199 * to consider, and the on-disk state is consistent either way:
1200 *
1201 * (1) If none of the new uberblocks made it to disk, then the
1202 * previous uberblock will be the newest, and the odd labels
1203 * (which had not yet been touched) will be valid with respect
1204 * to that uberblock.
1205 *
1206 * (2) If one or more new uberblocks made it to disk, then they
1207 * will be the newest, and the even labels (which had all
1208 * been successfully committed) will be valid with respect
1209 * to the new uberblocks.
1210 */
1211 if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1212 return (error);
1213
1214 /*
1215 * Sync out odd labels for every dirty vdev. If the system dies
1216 * in the middle of this process, the even labels and the new
1217 * uberblocks will suffice to open the pool. The next time
1218 * the pool is opened, the first thing we'll do -- before any
1219 * user data is modified -- is mark every vdev dirty so that
1220 * all labels will be brought up to date. We flush the new labels
1221 * to disk to ensure that all odd-label updates are committed to
1222 * stable storage before the next transaction group begins.
1223 */
b128c09f 1224 return (vdev_label_sync_list(spa, 1, txg, flags));
34dc7c2f 1225}