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3741 zfs needs better comments
Submitted by: Will Andrews <willa@spectralogic.com>
Submitted by: Justin Gibbs <justing@spectralogic.com>
Submitted by: Alan Somers <alans@spectralogic.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
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--- old/usr/src/uts/common/fs/zfs/vdev_label.c
+++ new/usr/src/uts/common/fs/zfs/vdev_label.c
1 1 /*
2 2 * CDDL HEADER START
3 3 *
4 4 * The contents of this file are subject to the terms of the
5 5 * Common Development and Distribution License (the "License").
6 6 * You may not use this file except in compliance with the License.
7 7 *
8 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 9 * or http://www.opensolaris.org/os/licensing.
10 10 * See the License for the specific language governing permissions
11 11 * and limitations under the License.
12 12 *
13 13 * When distributing Covered Code, include this CDDL HEADER in each
14 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 15 * If applicable, add the following below this CDDL HEADER, with the
16 16 * fields enclosed by brackets "[]" replaced with your own identifying
17 17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 18 *
19 19 * CDDL HEADER END
20 20 */
21 21
22 22 /*
23 23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24 24 * Copyright (c) 2013 by Delphix. All rights reserved.
25 25 */
26 26
27 27 /*
28 28 * Virtual Device Labels
29 29 * ---------------------
30 30 *
31 31 * The vdev label serves several distinct purposes:
32 32 *
33 33 * 1. Uniquely identify this device as part of a ZFS pool and confirm its
34 34 * identity within the pool.
35 35 *
36 36 * 2. Verify that all the devices given in a configuration are present
37 37 * within the pool.
38 38 *
39 39 * 3. Determine the uberblock for the pool.
40 40 *
41 41 * 4. In case of an import operation, determine the configuration of the
42 42 * toplevel vdev of which it is a part.
43 43 *
44 44 * 5. If an import operation cannot find all the devices in the pool,
45 45 * provide enough information to the administrator to determine which
46 46 * devices are missing.
47 47 *
48 48 * It is important to note that while the kernel is responsible for writing the
49 49 * label, it only consumes the information in the first three cases. The
50 50 * latter information is only consumed in userland when determining the
51 51 * configuration to import a pool.
52 52 *
53 53 *
54 54 * Label Organization
55 55 * ------------------
56 56 *
57 57 * Before describing the contents of the label, it's important to understand how
58 58 * the labels are written and updated with respect to the uberblock.
59 59 *
60 60 * When the pool configuration is altered, either because it was newly created
61 61 * or a device was added, we want to update all the labels such that we can deal
62 62 * with fatal failure at any point. To this end, each disk has two labels which
63 63 * are updated before and after the uberblock is synced. Assuming we have
64 64 * labels and an uberblock with the following transaction groups:
65 65 *
66 66 * L1 UB L2
67 67 * +------+ +------+ +------+
68 68 * | | | | | |
69 69 * | t10 | | t10 | | t10 |
70 70 * | | | | | |
71 71 * +------+ +------+ +------+
72 72 *
73 73 * In this stable state, the labels and the uberblock were all updated within
74 74 * the same transaction group (10). Each label is mirrored and checksummed, so
75 75 * that we can detect when we fail partway through writing the label.
76 76 *
77 77 * In order to identify which labels are valid, the labels are written in the
78 78 * following manner:
79 79 *
80 80 * 1. For each vdev, update 'L1' to the new label
81 81 * 2. Update the uberblock
82 82 * 3. For each vdev, update 'L2' to the new label
83 83 *
84 84 * Given arbitrary failure, we can determine the correct label to use based on
85 85 * the transaction group. If we fail after updating L1 but before updating the
86 86 * UB, we will notice that L1's transaction group is greater than the uberblock,
87 87 * so L2 must be valid. If we fail after writing the uberblock but before
88 88 * writing L2, we will notice that L2's transaction group is less than L1, and
89 89 * therefore L1 is valid.
90 90 *
91 91 * Another added complexity is that not every label is updated when the config
92 92 * is synced. If we add a single device, we do not want to have to re-write
93 93 * every label for every device in the pool. This means that both L1 and L2 may
94 94 * be older than the pool uberblock, because the necessary information is stored
95 95 * on another vdev.
96 96 *
97 97 *
98 98 * On-disk Format
99 99 * --------------
100 100 *
101 101 * The vdev label consists of two distinct parts, and is wrapped within the
102 102 * vdev_label_t structure. The label includes 8k of padding to permit legacy
103 103 * VTOC disk labels, but is otherwise ignored.
104 104 *
105 105 * The first half of the label is a packed nvlist which contains pool wide
106 106 * properties, per-vdev properties, and configuration information. It is
107 107 * described in more detail below.
108 108 *
109 109 * The latter half of the label consists of a redundant array of uberblocks.
110 110 * These uberblocks are updated whenever a transaction group is committed,
111 111 * or when the configuration is updated. When a pool is loaded, we scan each
112 112 * vdev for the 'best' uberblock.
113 113 *
114 114 *
115 115 * Configuration Information
116 116 * -------------------------
117 117 *
118 118 * The nvlist describing the pool and vdev contains the following elements:
119 119 *
120 120 * version ZFS on-disk version
121 121 * name Pool name
122 122 * state Pool state
123 123 * txg Transaction group in which this label was written
124 124 * pool_guid Unique identifier for this pool
125 125 * vdev_tree An nvlist describing vdev tree.
126 126 * features_for_read
127 127 * An nvlist of the features necessary for reading the MOS.
128 128 *
129 129 * Each leaf device label also contains the following:
130 130 *
131 131 * top_guid Unique ID for top-level vdev in which this is contained
132 132 * guid Unique ID for the leaf vdev
133 133 *
134 134 * The 'vs' configuration follows the format described in 'spa_config.c'.
135 135 */
136 136
137 137 #include <sys/zfs_context.h>
138 138 #include <sys/spa.h>
139 139 #include <sys/spa_impl.h>
140 140 #include <sys/dmu.h>
141 141 #include <sys/zap.h>
142 142 #include <sys/vdev.h>
143 143 #include <sys/vdev_impl.h>
144 144 #include <sys/uberblock_impl.h>
145 145 #include <sys/metaslab.h>
146 146 #include <sys/zio.h>
147 147 #include <sys/dsl_scan.h>
148 148 #include <sys/fs/zfs.h>
149 149
150 150 /*
151 151 * Basic routines to read and write from a vdev label.
152 152 * Used throughout the rest of this file.
153 153 */
154 154 uint64_t
155 155 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
156 156 {
157 157 ASSERT(offset < sizeof (vdev_label_t));
158 158 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
159 159
160 160 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
161 161 0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
162 162 }
163 163
164 164 /*
165 165 * Returns back the vdev label associated with the passed in offset.
166 166 */
167 167 int
168 168 vdev_label_number(uint64_t psize, uint64_t offset)
169 169 {
170 170 int l;
171 171
172 172 if (offset >= psize - VDEV_LABEL_END_SIZE) {
173 173 offset -= psize - VDEV_LABEL_END_SIZE;
174 174 offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
175 175 }
176 176 l = offset / sizeof (vdev_label_t);
177 177 return (l < VDEV_LABELS ? l : -1);
178 178 }
179 179
180 180 static void
181 181 vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
182 182 uint64_t size, zio_done_func_t *done, void *private, int flags)
183 183 {
184 184 ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
185 185 SCL_STATE_ALL);
186 186 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
187 187
188 188 zio_nowait(zio_read_phys(zio, vd,
189 189 vdev_label_offset(vd->vdev_psize, l, offset),
190 190 size, buf, ZIO_CHECKSUM_LABEL, done, private,
191 191 ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
192 192 }
193 193
194 194 static void
195 195 vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
196 196 uint64_t size, zio_done_func_t *done, void *private, int flags)
197 197 {
198 198 ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
199 199 (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
200 200 (SCL_CONFIG | SCL_STATE) &&
201 201 dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
202 202 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
203 203
204 204 zio_nowait(zio_write_phys(zio, vd,
205 205 vdev_label_offset(vd->vdev_psize, l, offset),
206 206 size, buf, ZIO_CHECKSUM_LABEL, done, private,
207 207 ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
208 208 }
209 209
210 210 /*
211 211 * Generate the nvlist representing this vdev's config.
212 212 */
213 213 nvlist_t *
214 214 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
215 215 vdev_config_flag_t flags)
216 216 {
217 217 nvlist_t *nv = NULL;
218 218
219 219 VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
220 220
221 221 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE,
222 222 vd->vdev_ops->vdev_op_type) == 0);
223 223 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
224 224 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id)
225 225 == 0);
226 226 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0);
227 227
228 228 if (vd->vdev_path != NULL)
229 229 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH,
230 230 vd->vdev_path) == 0);
231 231
232 232 if (vd->vdev_devid != NULL)
233 233 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID,
234 234 vd->vdev_devid) == 0);
235 235
236 236 if (vd->vdev_physpath != NULL)
237 237 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
238 238 vd->vdev_physpath) == 0);
239 239
240 240 if (vd->vdev_fru != NULL)
241 241 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_FRU,
242 242 vd->vdev_fru) == 0);
243 243
244 244 if (vd->vdev_nparity != 0) {
245 245 ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
246 246 VDEV_TYPE_RAIDZ) == 0);
247 247
248 248 /*
249 249 * Make sure someone hasn't managed to sneak a fancy new vdev
250 250 * into a crufty old storage pool.
251 251 */
252 252 ASSERT(vd->vdev_nparity == 1 ||
253 253 (vd->vdev_nparity <= 2 &&
254 254 spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
255 255 (vd->vdev_nparity <= 3 &&
256 256 spa_version(spa) >= SPA_VERSION_RAIDZ3));
257 257
258 258 /*
259 259 * Note that we'll add the nparity tag even on storage pools
260 260 * that only support a single parity device -- older software
261 261 * will just ignore it.
262 262 */
263 263 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY,
264 264 vd->vdev_nparity) == 0);
265 265 }
266 266
267 267 if (vd->vdev_wholedisk != -1ULL)
268 268 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
269 269 vd->vdev_wholedisk) == 0);
270 270
271 271 if (vd->vdev_not_present)
272 272 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0);
273 273
274 274 if (vd->vdev_isspare)
275 275 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0);
276 276
277 277 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
278 278 vd == vd->vdev_top) {
279 279 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
280 280 vd->vdev_ms_array) == 0);
281 281 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
282 282 vd->vdev_ms_shift) == 0);
283 283 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT,
284 284 vd->vdev_ashift) == 0);
285 285 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
286 286 vd->vdev_asize) == 0);
287 287 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG,
288 288 vd->vdev_islog) == 0);
289 289 if (vd->vdev_removing)
290 290 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
291 291 vd->vdev_removing) == 0);
292 292 }
293 293
294 294 if (vd->vdev_dtl_smo.smo_object != 0)
295 295 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
296 296 vd->vdev_dtl_smo.smo_object) == 0);
297 297
298 298 if (vd->vdev_crtxg)
299 299 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
300 300 vd->vdev_crtxg) == 0);
301 301
302 302 if (getstats) {
303 303 vdev_stat_t vs;
304 304 pool_scan_stat_t ps;
305 305
306 306 vdev_get_stats(vd, &vs);
307 307 VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
308 308 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0);
309 309
310 310 /* provide either current or previous scan information */
311 311 if (spa_scan_get_stats(spa, &ps) == 0) {
312 312 VERIFY(nvlist_add_uint64_array(nv,
313 313 ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
314 314 sizeof (pool_scan_stat_t) / sizeof (uint64_t))
315 315 == 0);
316 316 }
317 317 }
318 318
319 319 if (!vd->vdev_ops->vdev_op_leaf) {
320 320 nvlist_t **child;
321 321 int c, idx;
322 322
323 323 ASSERT(!vd->vdev_ishole);
324 324
325 325 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
326 326 KM_SLEEP);
327 327
328 328 for (c = 0, idx = 0; c < vd->vdev_children; c++) {
329 329 vdev_t *cvd = vd->vdev_child[c];
330 330
331 331 /*
332 332 * If we're generating an nvlist of removing
333 333 * vdevs then skip over any device which is
334 334 * not being removed.
335 335 */
336 336 if ((flags & VDEV_CONFIG_REMOVING) &&
337 337 !cvd->vdev_removing)
338 338 continue;
339 339
340 340 child[idx++] = vdev_config_generate(spa, cvd,
341 341 getstats, flags);
342 342 }
343 343
344 344 if (idx) {
345 345 VERIFY(nvlist_add_nvlist_array(nv,
346 346 ZPOOL_CONFIG_CHILDREN, child, idx) == 0);
347 347 }
348 348
349 349 for (c = 0; c < idx; c++)
350 350 nvlist_free(child[c]);
351 351
352 352 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
353 353
354 354 } else {
355 355 const char *aux = NULL;
356 356
357 357 if (vd->vdev_offline && !vd->vdev_tmpoffline)
358 358 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE,
359 359 B_TRUE) == 0);
360 360 if (vd->vdev_resilvering)
361 361 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVERING,
362 362 B_TRUE) == 0);
363 363 if (vd->vdev_faulted)
364 364 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED,
365 365 B_TRUE) == 0);
366 366 if (vd->vdev_degraded)
367 367 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED,
368 368 B_TRUE) == 0);
369 369 if (vd->vdev_removed)
370 370 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED,
371 371 B_TRUE) == 0);
372 372 if (vd->vdev_unspare)
373 373 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE,
374 374 B_TRUE) == 0);
375 375 if (vd->vdev_ishole)
376 376 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE,
377 377 B_TRUE) == 0);
378 378
379 379 switch (vd->vdev_stat.vs_aux) {
380 380 case VDEV_AUX_ERR_EXCEEDED:
381 381 aux = "err_exceeded";
382 382 break;
383 383
384 384 case VDEV_AUX_EXTERNAL:
385 385 aux = "external";
386 386 break;
387 387 }
388 388
389 389 if (aux != NULL)
390 390 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE,
391 391 aux) == 0);
392 392
393 393 if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
394 394 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
395 395 vd->vdev_orig_guid) == 0);
396 396 }
397 397 }
398 398
399 399 return (nv);
400 400 }
401 401
402 402 /*
403 403 * Generate a view of the top-level vdevs. If we currently have holes
404 404 * in the namespace, then generate an array which contains a list of holey
405 405 * vdevs. Additionally, add the number of top-level children that currently
406 406 * exist.
407 407 */
408 408 void
409 409 vdev_top_config_generate(spa_t *spa, nvlist_t *config)
410 410 {
411 411 vdev_t *rvd = spa->spa_root_vdev;
412 412 uint64_t *array;
413 413 uint_t c, idx;
414 414
415 415 array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP);
416 416
417 417 for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
418 418 vdev_t *tvd = rvd->vdev_child[c];
419 419
420 420 if (tvd->vdev_ishole)
421 421 array[idx++] = c;
422 422 }
423 423
424 424 if (idx) {
425 425 VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
426 426 array, idx) == 0);
427 427 }
428 428
429 429 VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
430 430 rvd->vdev_children) == 0);
431 431
432 432 kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
433 433 }
434 434
435 435 /*
436 436 * Returns the configuration from the label of the given vdev. For vdevs
437 437 * which don't have a txg value stored on their label (i.e. spares/cache)
438 438 * or have not been completely initialized (txg = 0) just return
439 439 * the configuration from the first valid label we find. Otherwise,
440 440 * find the most up-to-date label that does not exceed the specified
441 441 * 'txg' value.
442 442 */
443 443 nvlist_t *
444 444 vdev_label_read_config(vdev_t *vd, uint64_t txg)
445 445 {
446 446 spa_t *spa = vd->vdev_spa;
447 447 nvlist_t *config = NULL;
448 448 vdev_phys_t *vp;
449 449 zio_t *zio;
450 450 uint64_t best_txg = 0;
451 451 int error = 0;
452 452 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
453 453 ZIO_FLAG_SPECULATIVE;
454 454
455 455 ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
456 456
457 457 if (!vdev_readable(vd))
458 458 return (NULL);
459 459
460 460 vp = zio_buf_alloc(sizeof (vdev_phys_t));
461 461
462 462 retry:
463 463 for (int l = 0; l < VDEV_LABELS; l++) {
464 464 nvlist_t *label = NULL;
465 465
466 466 zio = zio_root(spa, NULL, NULL, flags);
467 467
468 468 vdev_label_read(zio, vd, l, vp,
469 469 offsetof(vdev_label_t, vl_vdev_phys),
470 470 sizeof (vdev_phys_t), NULL, NULL, flags);
471 471
472 472 if (zio_wait(zio) == 0 &&
473 473 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
474 474 &label, 0) == 0) {
475 475 uint64_t label_txg = 0;
476 476
477 477 /*
478 478 * Auxiliary vdevs won't have txg values in their
479 479 * labels and newly added vdevs may not have been
480 480 * completely initialized so just return the
481 481 * configuration from the first valid label we
482 482 * encounter.
483 483 */
484 484 error = nvlist_lookup_uint64(label,
485 485 ZPOOL_CONFIG_POOL_TXG, &label_txg);
486 486 if ((error || label_txg == 0) && !config) {
487 487 config = label;
488 488 break;
489 489 } else if (label_txg <= txg && label_txg > best_txg) {
490 490 best_txg = label_txg;
491 491 nvlist_free(config);
492 492 config = fnvlist_dup(label);
493 493 }
494 494 }
495 495
496 496 if (label != NULL) {
497 497 nvlist_free(label);
498 498 label = NULL;
499 499 }
500 500 }
501 501
502 502 if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
503 503 flags |= ZIO_FLAG_TRYHARD;
504 504 goto retry;
505 505 }
506 506
507 507 zio_buf_free(vp, sizeof (vdev_phys_t));
508 508
509 509 return (config);
510 510 }
511 511
512 512 /*
513 513 * Determine if a device is in use. The 'spare_guid' parameter will be filled
514 514 * in with the device guid if this spare is active elsewhere on the system.
515 515 */
516 516 static boolean_t
517 517 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
518 518 uint64_t *spare_guid, uint64_t *l2cache_guid)
519 519 {
520 520 spa_t *spa = vd->vdev_spa;
521 521 uint64_t state, pool_guid, device_guid, txg, spare_pool;
522 522 uint64_t vdtxg = 0;
523 523 nvlist_t *label;
524 524
525 525 if (spare_guid)
526 526 *spare_guid = 0ULL;
527 527 if (l2cache_guid)
528 528 *l2cache_guid = 0ULL;
529 529
530 530 /*
531 531 * Read the label, if any, and perform some basic sanity checks.
532 532 */
533 533 if ((label = vdev_label_read_config(vd, -1ULL)) == NULL)
534 534 return (B_FALSE);
535 535
536 536 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
537 537 &vdtxg);
538 538
539 539 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
540 540 &state) != 0 ||
541 541 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
542 542 &device_guid) != 0) {
543 543 nvlist_free(label);
544 544 return (B_FALSE);
545 545 }
546 546
547 547 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
548 548 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
549 549 &pool_guid) != 0 ||
550 550 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
551 551 &txg) != 0)) {
552 552 nvlist_free(label);
553 553 return (B_FALSE);
554 554 }
555 555
556 556 nvlist_free(label);
557 557
558 558 /*
559 559 * Check to see if this device indeed belongs to the pool it claims to
560 560 * be a part of. The only way this is allowed is if the device is a hot
561 561 * spare (which we check for later on).
562 562 */
563 563 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
564 564 !spa_guid_exists(pool_guid, device_guid) &&
565 565 !spa_spare_exists(device_guid, NULL, NULL) &&
566 566 !spa_l2cache_exists(device_guid, NULL))
567 567 return (B_FALSE);
568 568
569 569 /*
570 570 * If the transaction group is zero, then this an initialized (but
571 571 * unused) label. This is only an error if the create transaction
572 572 * on-disk is the same as the one we're using now, in which case the
573 573 * user has attempted to add the same vdev multiple times in the same
574 574 * transaction.
575 575 */
576 576 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
577 577 txg == 0 && vdtxg == crtxg)
578 578 return (B_TRUE);
579 579
580 580 /*
581 581 * Check to see if this is a spare device. We do an explicit check for
582 582 * spa_has_spare() here because it may be on our pending list of spares
583 583 * to add. We also check if it is an l2cache device.
584 584 */
585 585 if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
586 586 spa_has_spare(spa, device_guid)) {
587 587 if (spare_guid)
588 588 *spare_guid = device_guid;
589 589
590 590 switch (reason) {
591 591 case VDEV_LABEL_CREATE:
592 592 case VDEV_LABEL_L2CACHE:
593 593 return (B_TRUE);
594 594
595 595 case VDEV_LABEL_REPLACE:
596 596 return (!spa_has_spare(spa, device_guid) ||
597 597 spare_pool != 0ULL);
598 598
599 599 case VDEV_LABEL_SPARE:
600 600 return (spa_has_spare(spa, device_guid));
601 601 }
602 602 }
603 603
604 604 /*
605 605 * Check to see if this is an l2cache device.
606 606 */
607 607 if (spa_l2cache_exists(device_guid, NULL))
608 608 return (B_TRUE);
609 609
610 610 /*
611 611 * We can't rely on a pool's state if it's been imported
612 612 * read-only. Instead we look to see if the pools is marked
613 613 * read-only in the namespace and set the state to active.
614 614 */
615 615 if ((spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
616 616 spa_mode(spa) == FREAD)
617 617 state = POOL_STATE_ACTIVE;
618 618
619 619 /*
620 620 * If the device is marked ACTIVE, then this device is in use by another
621 621 * pool on the system.
622 622 */
623 623 return (state == POOL_STATE_ACTIVE);
624 624 }
625 625
626 626 /*
627 627 * Initialize a vdev label. We check to make sure each leaf device is not in
628 628 * use, and writable. We put down an initial label which we will later
629 629 * overwrite with a complete label. Note that it's important to do this
630 630 * sequentially, not in parallel, so that we catch cases of multiple use of the
631 631 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
632 632 * itself.
633 633 */
634 634 int
635 635 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
636 636 {
637 637 spa_t *spa = vd->vdev_spa;
638 638 nvlist_t *label;
639 639 vdev_phys_t *vp;
640 640 char *pad2;
641 641 uberblock_t *ub;
642 642 zio_t *zio;
643 643 char *buf;
644 644 size_t buflen;
645 645 int error;
646 646 uint64_t spare_guid, l2cache_guid;
647 647 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
648 648
649 649 ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
650 650
651 651 for (int c = 0; c < vd->vdev_children; c++)
652 652 if ((error = vdev_label_init(vd->vdev_child[c],
653 653 crtxg, reason)) != 0)
654 654 return (error);
655 655
656 656 /* Track the creation time for this vdev */
657 657 vd->vdev_crtxg = crtxg;
658 658
659 659 if (!vd->vdev_ops->vdev_op_leaf)
660 660 return (0);
661 661
662 662 /*
663 663 * Dead vdevs cannot be initialized.
664 664 */
665 665 if (vdev_is_dead(vd))
666 666 return (SET_ERROR(EIO));
667 667
668 668 /*
669 669 * Determine if the vdev is in use.
670 670 */
671 671 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
672 672 vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
673 673 return (SET_ERROR(EBUSY));
674 674
675 675 /*
676 676 * If this is a request to add or replace a spare or l2cache device
677 677 * that is in use elsewhere on the system, then we must update the
678 678 * guid (which was initialized to a random value) to reflect the
679 679 * actual GUID (which is shared between multiple pools).
680 680 */
681 681 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
682 682 spare_guid != 0ULL) {
683 683 uint64_t guid_delta = spare_guid - vd->vdev_guid;
684 684
685 685 vd->vdev_guid += guid_delta;
686 686
687 687 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
688 688 pvd->vdev_guid_sum += guid_delta;
689 689
690 690 /*
691 691 * If this is a replacement, then we want to fallthrough to the
692 692 * rest of the code. If we're adding a spare, then it's already
693 693 * labeled appropriately and we can just return.
694 694 */
695 695 if (reason == VDEV_LABEL_SPARE)
696 696 return (0);
697 697 ASSERT(reason == VDEV_LABEL_REPLACE ||
698 698 reason == VDEV_LABEL_SPLIT);
699 699 }
700 700
701 701 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
702 702 l2cache_guid != 0ULL) {
703 703 uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
704 704
705 705 vd->vdev_guid += guid_delta;
706 706
707 707 for (vdev_t *pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
708 708 pvd->vdev_guid_sum += guid_delta;
709 709
710 710 /*
711 711 * If this is a replacement, then we want to fallthrough to the
712 712 * rest of the code. If we're adding an l2cache, then it's
713 713 * already labeled appropriately and we can just return.
714 714 */
715 715 if (reason == VDEV_LABEL_L2CACHE)
716 716 return (0);
717 717 ASSERT(reason == VDEV_LABEL_REPLACE);
718 718 }
719 719
720 720 /*
721 721 * Initialize its label.
722 722 */
723 723 vp = zio_buf_alloc(sizeof (vdev_phys_t));
724 724 bzero(vp, sizeof (vdev_phys_t));
725 725
726 726 /*
727 727 * Generate a label describing the pool and our top-level vdev.
728 728 * We mark it as being from txg 0 to indicate that it's not
729 729 * really part of an active pool just yet. The labels will
730 730 * be written again with a meaningful txg by spa_sync().
731 731 */
732 732 if (reason == VDEV_LABEL_SPARE ||
733 733 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
734 734 /*
735 735 * For inactive hot spares, we generate a special label that
736 736 * identifies as a mutually shared hot spare. We write the
737 737 * label if we are adding a hot spare, or if we are removing an
738 738 * active hot spare (in which case we want to revert the
739 739 * labels).
740 740 */
741 741 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
742 742
743 743 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
744 744 spa_version(spa)) == 0);
745 745 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
746 746 POOL_STATE_SPARE) == 0);
747 747 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
748 748 vd->vdev_guid) == 0);
749 749 } else if (reason == VDEV_LABEL_L2CACHE ||
750 750 (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
751 751 /*
752 752 * For level 2 ARC devices, add a special label.
753 753 */
754 754 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0);
755 755
756 756 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
757 757 spa_version(spa)) == 0);
758 758 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
759 759 POOL_STATE_L2CACHE) == 0);
760 760 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
761 761 vd->vdev_guid) == 0);
762 762 } else {
763 763 uint64_t txg = 0ULL;
764 764
765 765 if (reason == VDEV_LABEL_SPLIT)
766 766 txg = spa->spa_uberblock.ub_txg;
767 767 label = spa_config_generate(spa, vd, txg, B_FALSE);
768 768
769 769 /*
770 770 * Add our creation time. This allows us to detect multiple
771 771 * vdev uses as described above, and automatically expires if we
772 772 * fail.
773 773 */
774 774 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
775 775 crtxg) == 0);
776 776 }
777 777
778 778 buf = vp->vp_nvlist;
779 779 buflen = sizeof (vp->vp_nvlist);
780 780
781 781 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP);
782 782 if (error != 0) {
783 783 nvlist_free(label);
784 784 zio_buf_free(vp, sizeof (vdev_phys_t));
785 785 /* EFAULT means nvlist_pack ran out of room */
786 786 return (error == EFAULT ? ENAMETOOLONG : EINVAL);
787 787 }
788 788
789 789 /*
790 790 * Initialize uberblock template.
791 791 */
792 792 ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
793 793 bzero(ub, VDEV_UBERBLOCK_RING);
794 794 *ub = spa->spa_uberblock;
795 795 ub->ub_txg = 0;
796 796
797 797 /* Initialize the 2nd padding area. */
798 798 pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
799 799 bzero(pad2, VDEV_PAD_SIZE);
800 800
801 801 /*
802 802 * Write everything in parallel.
803 803 */
804 804 retry:
805 805 zio = zio_root(spa, NULL, NULL, flags);
806 806
807 807 for (int l = 0; l < VDEV_LABELS; l++) {
808 808
809 809 vdev_label_write(zio, vd, l, vp,
810 810 offsetof(vdev_label_t, vl_vdev_phys),
811 811 sizeof (vdev_phys_t), NULL, NULL, flags);
812 812
813 813 /*
814 814 * Skip the 1st padding area.
815 815 * Zero out the 2nd padding area where it might have
816 816 * left over data from previous filesystem format.
817 817 */
818 818 vdev_label_write(zio, vd, l, pad2,
819 819 offsetof(vdev_label_t, vl_pad2),
820 820 VDEV_PAD_SIZE, NULL, NULL, flags);
821 821
822 822 vdev_label_write(zio, vd, l, ub,
823 823 offsetof(vdev_label_t, vl_uberblock),
824 824 VDEV_UBERBLOCK_RING, NULL, NULL, flags);
825 825 }
826 826
827 827 error = zio_wait(zio);
828 828
829 829 if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
830 830 flags |= ZIO_FLAG_TRYHARD;
831 831 goto retry;
832 832 }
833 833
834 834 nvlist_free(label);
835 835 zio_buf_free(pad2, VDEV_PAD_SIZE);
836 836 zio_buf_free(ub, VDEV_UBERBLOCK_RING);
837 837 zio_buf_free(vp, sizeof (vdev_phys_t));
838 838
839 839 /*
840 840 * If this vdev hasn't been previously identified as a spare, then we
841 841 * mark it as such only if a) we are labeling it as a spare, or b) it
842 842 * exists as a spare elsewhere in the system. Do the same for
843 843 * level 2 ARC devices.
844 844 */
845 845 if (error == 0 && !vd->vdev_isspare &&
846 846 (reason == VDEV_LABEL_SPARE ||
847 847 spa_spare_exists(vd->vdev_guid, NULL, NULL)))
848 848 spa_spare_add(vd);
849 849
850 850 if (error == 0 && !vd->vdev_isl2cache &&
851 851 (reason == VDEV_LABEL_L2CACHE ||
852 852 spa_l2cache_exists(vd->vdev_guid, NULL)))
853 853 spa_l2cache_add(vd);
854 854
855 855 return (error);
856 856 }
857 857
858 858 /*
859 859 * ==========================================================================
860 860 * uberblock load/sync
861 861 * ==========================================================================
862 862 */
863 863
864 864 /*
865 865 * Consider the following situation: txg is safely synced to disk. We've
866 866 * written the first uberblock for txg + 1, and then we lose power. When we
867 867 * come back up, we fail to see the uberblock for txg + 1 because, say,
868 868 * it was on a mirrored device and the replica to which we wrote txg + 1
869 869 * is now offline. If we then make some changes and sync txg + 1, and then
870 870 * the missing replica comes back, then for a few seconds we'll have two
871 871 * conflicting uberblocks on disk with the same txg. The solution is simple:
872 872 * among uberblocks with equal txg, choose the one with the latest timestamp.
873 873 */
874 874 static int
875 875 vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
876 876 {
877 877 if (ub1->ub_txg < ub2->ub_txg)
878 878 return (-1);
879 879 if (ub1->ub_txg > ub2->ub_txg)
880 880 return (1);
881 881
882 882 if (ub1->ub_timestamp < ub2->ub_timestamp)
883 883 return (-1);
884 884 if (ub1->ub_timestamp > ub2->ub_timestamp)
885 885 return (1);
886 886
887 887 return (0);
888 888 }
889 889
890 890 struct ubl_cbdata {
891 891 uberblock_t *ubl_ubbest; /* Best uberblock */
892 892 vdev_t *ubl_vd; /* vdev associated with the above */
893 893 };
894 894
895 895 static void
896 896 vdev_uberblock_load_done(zio_t *zio)
897 897 {
898 898 vdev_t *vd = zio->io_vd;
899 899 spa_t *spa = zio->io_spa;
900 900 zio_t *rio = zio->io_private;
901 901 uberblock_t *ub = zio->io_data;
902 902 struct ubl_cbdata *cbp = rio->io_private;
903 903
904 904 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
905 905
906 906 if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
907 907 mutex_enter(&rio->io_lock);
908 908 if (ub->ub_txg <= spa->spa_load_max_txg &&
909 909 vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
910 910 /*
911 911 * Keep track of the vdev in which this uberblock
912 912 * was found. We will use this information later
913 913 * to obtain the config nvlist associated with
914 914 * this uberblock.
915 915 */
916 916 *cbp->ubl_ubbest = *ub;
917 917 cbp->ubl_vd = vd;
918 918 }
919 919 mutex_exit(&rio->io_lock);
920 920 }
921 921
922 922 zio_buf_free(zio->io_data, zio->io_size);
923 923 }
924 924
925 925 static void
926 926 vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
927 927 struct ubl_cbdata *cbp)
928 928 {
929 929 for (int c = 0; c < vd->vdev_children; c++)
930 930 vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp);
931 931
932 932 if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
933 933 for (int l = 0; l < VDEV_LABELS; l++) {
934 934 for (int n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
935 935 vdev_label_read(zio, vd, l,
936 936 zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
937 937 VDEV_UBERBLOCK_OFFSET(vd, n),
938 938 VDEV_UBERBLOCK_SIZE(vd),
939 939 vdev_uberblock_load_done, zio, flags);
940 940 }
941 941 }
942 942 }
943 943 }
944 944
945 945 /*
946 946 * Reads the 'best' uberblock from disk along with its associated
947 947 * configuration. First, we read the uberblock array of each label of each
948 948 * vdev, keeping track of the uberblock with the highest txg in each array.
949 949 * Then, we read the configuration from the same vdev as the best uberblock.
950 950 */
951 951 void
952 952 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
953 953 {
954 954 zio_t *zio;
955 955 spa_t *spa = rvd->vdev_spa;
956 956 struct ubl_cbdata cb;
957 957 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
958 958 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
959 959
960 960 ASSERT(ub);
961 961 ASSERT(config);
962 962
963 963 bzero(ub, sizeof (uberblock_t));
964 964 *config = NULL;
965 965
966 966 cb.ubl_ubbest = ub;
967 967 cb.ubl_vd = NULL;
968 968
969 969 spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
970 970 zio = zio_root(spa, NULL, &cb, flags);
971 971 vdev_uberblock_load_impl(zio, rvd, flags, &cb);
972 972 (void) zio_wait(zio);
973 973
974 974 /*
975 975 * It's possible that the best uberblock was discovered on a label
976 976 * that has a configuration which was written in a future txg.
977 977 * Search all labels on this vdev to find the configuration that
978 978 * matches the txg for our uberblock.
979 979 */
980 980 if (cb.ubl_vd != NULL)
981 981 *config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg);
982 982 spa_config_exit(spa, SCL_ALL, FTAG);
983 983 }
984 984
985 985 /*
986 986 * On success, increment root zio's count of good writes.
987 987 * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
988 988 */
989 989 static void
990 990 vdev_uberblock_sync_done(zio_t *zio)
991 991 {
992 992 uint64_t *good_writes = zio->io_private;
993 993
994 994 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
995 995 atomic_add_64(good_writes, 1);
996 996 }
997 997
998 998 /*
999 999 * Write the uberblock to all labels of all leaves of the specified vdev.
1000 1000 */
1001 1001 static void
1002 1002 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
1003 1003 {
1004 1004 uberblock_t *ubbuf;
1005 1005 int n;
1006 1006
1007 1007 for (int c = 0; c < vd->vdev_children; c++)
1008 1008 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
1009 1009
1010 1010 if (!vd->vdev_ops->vdev_op_leaf)
1011 1011 return;
1012 1012
1013 1013 if (!vdev_writeable(vd))
1014 1014 return;
1015 1015
1016 1016 n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
1017 1017
1018 1018 ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
1019 1019 bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
1020 1020 *ubbuf = *ub;
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1021 1021
1022 1022 for (int l = 0; l < VDEV_LABELS; l++)
1023 1023 vdev_label_write(zio, vd, l, ubbuf,
1024 1024 VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1025 1025 vdev_uberblock_sync_done, zio->io_private,
1026 1026 flags | ZIO_FLAG_DONT_PROPAGATE);
1027 1027
1028 1028 zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
1029 1029 }
1030 1030
1031 +/* Sync the uberblocks to all vdevs in svd[] */
1031 1032 int
1032 1033 vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
1033 1034 {
1034 1035 spa_t *spa = svd[0]->vdev_spa;
1035 1036 zio_t *zio;
1036 1037 uint64_t good_writes = 0;
1037 1038
1038 1039 zio = zio_root(spa, NULL, &good_writes, flags);
1039 1040
1040 1041 for (int v = 0; v < svdcount; v++)
1041 1042 vdev_uberblock_sync(zio, ub, svd[v], flags);
1042 1043
1043 1044 (void) zio_wait(zio);
1044 1045
1045 1046 /*
1046 1047 * Flush the uberblocks to disk. This ensures that the odd labels
1047 1048 * are no longer needed (because the new uberblocks and the even
1048 1049 * labels are safely on disk), so it is safe to overwrite them.
1049 1050 */
1050 1051 zio = zio_root(spa, NULL, NULL, flags);
1051 1052
1052 1053 for (int v = 0; v < svdcount; v++)
1053 1054 zio_flush(zio, svd[v]);
1054 1055
1055 1056 (void) zio_wait(zio);
1056 1057
1057 1058 return (good_writes >= 1 ? 0 : EIO);
1058 1059 }
1059 1060
1060 1061 /*
1061 1062 * On success, increment the count of good writes for our top-level vdev.
1062 1063 */
1063 1064 static void
1064 1065 vdev_label_sync_done(zio_t *zio)
1065 1066 {
1066 1067 uint64_t *good_writes = zio->io_private;
1067 1068
1068 1069 if (zio->io_error == 0)
1069 1070 atomic_add_64(good_writes, 1);
1070 1071 }
1071 1072
1072 1073 /*
1073 1074 * If there weren't enough good writes, indicate failure to the parent.
1074 1075 */
1075 1076 static void
1076 1077 vdev_label_sync_top_done(zio_t *zio)
1077 1078 {
1078 1079 uint64_t *good_writes = zio->io_private;
1079 1080
1080 1081 if (*good_writes == 0)
1081 1082 zio->io_error = SET_ERROR(EIO);
1082 1083
1083 1084 kmem_free(good_writes, sizeof (uint64_t));
1084 1085 }
1085 1086
1086 1087 /*
1087 1088 * We ignore errors for log and cache devices, simply free the private data.
1088 1089 */
1089 1090 static void
1090 1091 vdev_label_sync_ignore_done(zio_t *zio)
1091 1092 {
1092 1093 kmem_free(zio->io_private, sizeof (uint64_t));
1093 1094 }
1094 1095
1095 1096 /*
1096 1097 * Write all even or odd labels to all leaves of the specified vdev.
1097 1098 */
1098 1099 static void
1099 1100 vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
1100 1101 {
1101 1102 nvlist_t *label;
1102 1103 vdev_phys_t *vp;
1103 1104 char *buf;
1104 1105 size_t buflen;
1105 1106
1106 1107 for (int c = 0; c < vd->vdev_children; c++)
1107 1108 vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
1108 1109
1109 1110 if (!vd->vdev_ops->vdev_op_leaf)
1110 1111 return;
1111 1112
1112 1113 if (!vdev_writeable(vd))
1113 1114 return;
1114 1115
1115 1116 /*
1116 1117 * Generate a label describing the top-level config to which we belong.
1117 1118 */
1118 1119 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1119 1120
1120 1121 vp = zio_buf_alloc(sizeof (vdev_phys_t));
1121 1122 bzero(vp, sizeof (vdev_phys_t));
1122 1123
1123 1124 buf = vp->vp_nvlist;
1124 1125 buflen = sizeof (vp->vp_nvlist);
1125 1126
1126 1127 if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) {
1127 1128 for (; l < VDEV_LABELS; l += 2) {
1128 1129 vdev_label_write(zio, vd, l, vp,
1129 1130 offsetof(vdev_label_t, vl_vdev_phys),
1130 1131 sizeof (vdev_phys_t),
1131 1132 vdev_label_sync_done, zio->io_private,
1132 1133 flags | ZIO_FLAG_DONT_PROPAGATE);
1133 1134 }
1134 1135 }
1135 1136
1136 1137 zio_buf_free(vp, sizeof (vdev_phys_t));
1137 1138 nvlist_free(label);
1138 1139 }
1139 1140
1140 1141 int
1141 1142 vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
1142 1143 {
1143 1144 list_t *dl = &spa->spa_config_dirty_list;
1144 1145 vdev_t *vd;
1145 1146 zio_t *zio;
1146 1147 int error;
1147 1148
1148 1149 /*
1149 1150 * Write the new labels to disk.
1150 1151 */
1151 1152 zio = zio_root(spa, NULL, NULL, flags);
1152 1153
1153 1154 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
1154 1155 uint64_t *good_writes = kmem_zalloc(sizeof (uint64_t),
1155 1156 KM_SLEEP);
1156 1157
1157 1158 ASSERT(!vd->vdev_ishole);
1158 1159
1159 1160 zio_t *vio = zio_null(zio, spa, NULL,
1160 1161 (vd->vdev_islog || vd->vdev_aux != NULL) ?
1161 1162 vdev_label_sync_ignore_done : vdev_label_sync_top_done,
1162 1163 good_writes, flags);
1163 1164 vdev_label_sync(vio, vd, l, txg, flags);
1164 1165 zio_nowait(vio);
1165 1166 }
1166 1167
1167 1168 error = zio_wait(zio);
1168 1169
1169 1170 /*
1170 1171 * Flush the new labels to disk.
1171 1172 */
1172 1173 zio = zio_root(spa, NULL, NULL, flags);
1173 1174
1174 1175 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
1175 1176 zio_flush(zio, vd);
1176 1177
1177 1178 (void) zio_wait(zio);
1178 1179
1179 1180 return (error);
1180 1181 }
1181 1182
1182 1183 /*
1183 1184 * Sync the uberblock and any changes to the vdev configuration.
1184 1185 *
1185 1186 * The order of operations is carefully crafted to ensure that
1186 1187 * if the system panics or loses power at any time, the state on disk
1187 1188 * is still transactionally consistent. The in-line comments below
1188 1189 * describe the failure semantics at each stage.
1189 1190 *
1190 1191 * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1191 1192 * at any time, you can just call it again, and it will resume its work.
1192 1193 */
1193 1194 int
1194 1195 vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg, boolean_t tryhard)
1195 1196 {
1196 1197 spa_t *spa = svd[0]->vdev_spa;
1197 1198 uberblock_t *ub = &spa->spa_uberblock;
1198 1199 vdev_t *vd;
1199 1200 zio_t *zio;
1200 1201 int error;
1201 1202 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1202 1203
1203 1204 /*
1204 1205 * Normally, we don't want to try too hard to write every label and
1205 1206 * uberblock. If there is a flaky disk, we don't want the rest of the
1206 1207 * sync process to block while we retry. But if we can't write a
1207 1208 * single label out, we should retry with ZIO_FLAG_TRYHARD before
1208 1209 * bailing out and declaring the pool faulted.
1209 1210 */
1210 1211 if (tryhard)
1211 1212 flags |= ZIO_FLAG_TRYHARD;
1212 1213
1213 1214 ASSERT(ub->ub_txg <= txg);
1214 1215
1215 1216 /*
1216 1217 * If this isn't a resync due to I/O errors,
1217 1218 * and nothing changed in this transaction group,
1218 1219 * and the vdev configuration hasn't changed,
1219 1220 * then there's nothing to do.
1220 1221 */
1221 1222 if (ub->ub_txg < txg &&
1222 1223 uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
1223 1224 list_is_empty(&spa->spa_config_dirty_list))
1224 1225 return (0);
1225 1226
1226 1227 if (txg > spa_freeze_txg(spa))
1227 1228 return (0);
1228 1229
1229 1230 ASSERT(txg <= spa->spa_final_txg);
1230 1231
1231 1232 /*
1232 1233 * Flush the write cache of every disk that's been written to
1233 1234 * in this transaction group. This ensures that all blocks
1234 1235 * written in this txg will be committed to stable storage
1235 1236 * before any uberblock that references them.
1236 1237 */
1237 1238 zio = zio_root(spa, NULL, NULL, flags);
1238 1239
1239 1240 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
1240 1241 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
1241 1242 zio_flush(zio, vd);
1242 1243
1243 1244 (void) zio_wait(zio);
1244 1245
1245 1246 /*
1246 1247 * Sync out the even labels (L0, L2) for every dirty vdev. If the
1247 1248 * system dies in the middle of this process, that's OK: all of the
1248 1249 * even labels that made it to disk will be newer than any uberblock,
1249 1250 * and will therefore be considered invalid. The odd labels (L1, L3),
1250 1251 * which have not yet been touched, will still be valid. We flush
1251 1252 * the new labels to disk to ensure that all even-label updates
1252 1253 * are committed to stable storage before the uberblock update.
1253 1254 */
1254 1255 if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
1255 1256 return (error);
1256 1257
1257 1258 /*
1258 1259 * Sync the uberblocks to all vdevs in svd[].
1259 1260 * If the system dies in the middle of this step, there are two cases
1260 1261 * to consider, and the on-disk state is consistent either way:
1261 1262 *
1262 1263 * (1) If none of the new uberblocks made it to disk, then the
1263 1264 * previous uberblock will be the newest, and the odd labels
1264 1265 * (which had not yet been touched) will be valid with respect
1265 1266 * to that uberblock.
1266 1267 *
1267 1268 * (2) If one or more new uberblocks made it to disk, then they
1268 1269 * will be the newest, and the even labels (which had all
1269 1270 * been successfully committed) will be valid with respect
1270 1271 * to the new uberblocks.
1271 1272 */
1272 1273 if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1273 1274 return (error);
1274 1275
1275 1276 /*
1276 1277 * Sync out odd labels for every dirty vdev. If the system dies
1277 1278 * in the middle of this process, the even labels and the new
1278 1279 * uberblocks will suffice to open the pool. The next time
1279 1280 * the pool is opened, the first thing we'll do -- before any
1280 1281 * user data is modified -- is mark every vdev dirty so that
1281 1282 * all labels will be brought up to date. We flush the new labels
1282 1283 * to disk to ensure that all odd-label updates are committed to
1283 1284 * stable storage before the next transaction group begins.
1284 1285 */
1285 1286 return (vdev_label_sync_list(spa, 1, txg, flags));
1286 1287 }
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