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 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26 #pragma ident "%Z%%M% %I% %E% SMI" 27 28 /* 29 * Virtual Device Labels 30 * --------------------- 31 * 32 * The vdev label serves several distinct purposes: 33 * 34 * 1. Uniquely identify this device as part of a ZFS pool and confirm its 35 * identity within the pool. 36 * 37 * 2. Verify that all the devices given in a configuration are present 38 * within the pool. 39 * 40 * 3. Determine the uberblock for the pool. 41 * 42 * 4. In case of an import operation, determine the configuration of the 43 * toplevel vdev of which it is a part. 44 * 45 * 5. If an import operation cannot find all the devices in the pool, 46 * provide enough information to the administrator to determine which 47 * devices are missing. 48 * 49 * It is important to note that while the kernel is responsible for writing the 50 * label, it only consumes the information in the first three cases. The 51 * latter information is only consumed in userland when determining the 52 * configuration to import a pool. 53 * 54 * 55 * Label Organization 56 * ------------------ 57 * 58 * Before describing the contents of the label, it's important to understand how 59 * the labels are written and updated with respect to the uberblock. 60 * 61 * When the pool configuration is altered, either because it was newly created 62 * or a device was added, we want to update all the labels such that we can deal 63 * with fatal failure at any point. To this end, each disk has two labels which 64 * are updated before and after the uberblock is synced. Assuming we have 65 * labels and an uberblock with the following transaction groups: 66 * 67 * L1 UB L2 68 * +------+ +------+ +------+ 69 * | | | | | | 70 * | t10 | | t10 | | t10 | 71 * | | | | | | 72 * +------+ +------+ +------+ 73 * 74 * In this stable state, the labels and the uberblock were all updated within 75 * the same transaction group (10). Each label is mirrored and checksummed, so 76 * that we can detect when we fail partway through writing the label. 77 * 78 * In order to identify which labels are valid, the labels are written in the 79 * following manner: 80 * 81 * 1. For each vdev, update 'L1' to the new label 82 * 2. Update the uberblock 83 * 3. For each vdev, update 'L2' to the new label 84 * 85 * Given arbitrary failure, we can determine the correct label to use based on 86 * the transaction group. If we fail after updating L1 but before updating the 87 * UB, we will notice that L1's transaction group is greater than the uberblock, 88 * so L2 must be valid. If we fail after writing the uberblock but before 89 * writing L2, we will notice that L2's transaction group is less than L1, and 90 * therefore L1 is valid. 91 * 92 * Another added complexity is that not every label is updated when the config 93 * is synced. If we add a single device, we do not want to have to re-write 94 * every label for every device in the pool. This means that both L1 and L2 may 95 * be older than the pool uberblock, because the necessary information is stored 96 * on another vdev. 97 * 98 * 99 * On-disk Format 100 * -------------- 101 * 102 * The vdev label consists of two distinct parts, and is wrapped within the 103 * vdev_label_t structure. The label includes 8k of padding to permit legacy 104 * VTOC disk labels, but is otherwise ignored. 105 * 106 * The first half of the label is a packed nvlist which contains pool wide 107 * properties, per-vdev properties, and configuration information. It is 108 * described in more detail below. 109 * 110 * The latter half of the label consists of a redundant array of uberblocks. 111 * These uberblocks are updated whenever a transaction group is committed, 112 * or when the configuration is updated. When a pool is loaded, we scan each 113 * vdev for the 'best' uberblock. 114 * 115 * 116 * Configuration Information 117 * ------------------------- 118 * 119 * The nvlist describing the pool and vdev contains the following elements: 120 * 121 * version ZFS on-disk version 122 * name Pool name 123 * state Pool state 124 * txg Transaction group in which this label was written 125 * pool_guid Unique identifier for this pool 126 * vdev_tree An nvlist describing vdev tree. 127 * 128 * Each leaf device label also contains the following: 129 * 130 * top_guid Unique ID for top-level vdev in which this is contained 131 * guid Unique ID for the leaf vdev 132 * 133 * The 'vs' configuration follows the format described in 'spa_config.c'. 134 */ 135 136 #include <sys/zfs_context.h> 137 #include <sys/spa.h> 138 #include <sys/spa_impl.h> 139 #include <sys/dmu.h> 140 #include <sys/zap.h> 141 #include <sys/vdev.h> 142 #include <sys/vdev_impl.h> 143 #include <sys/uberblock_impl.h> 144 #include <sys/metaslab.h> 145 #include <sys/zio.h> 146 #include <sys/fs/zfs.h> 147 148 /* 149 * Basic routines to read and write from a vdev label. 150 * Used throughout the rest of this file. 151 */ 152 uint64_t 153 vdev_label_offset(uint64_t psize, int l, uint64_t offset) 154 { 155 ASSERT(offset < sizeof (vdev_label_t)); 156 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0); 157 158 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ? 159 0 : psize - VDEV_LABELS * sizeof (vdev_label_t))); 160 } 161 162 static void 163 vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset, 164 uint64_t size, zio_done_func_t *done, void *private) 165 { 166 ASSERT(vd->vdev_children == 0); 167 168 zio_nowait(zio_read_phys(zio, vd, 169 vdev_label_offset(vd->vdev_psize, l, offset), 170 size, buf, ZIO_CHECKSUM_LABEL, done, private, 171 ZIO_PRIORITY_SYNC_READ, 172 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE)); 173 } 174 175 static void 176 vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset, 177 uint64_t size, zio_done_func_t *done, void *private) 178 { 179 ASSERT(vd->vdev_children == 0); 180 181 zio_nowait(zio_write_phys(zio, vd, 182 vdev_label_offset(vd->vdev_psize, l, offset), 183 size, buf, ZIO_CHECKSUM_LABEL, done, private, 184 ZIO_PRIORITY_SYNC_WRITE, ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL)); 185 } 186 187 /* 188 * Generate the nvlist representing this vdev's config. 189 */ 190 nvlist_t * 191 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats, 192 boolean_t isspare) 193 { 194 nvlist_t *nv = NULL; 195 196 VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0); 197 198 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_TYPE, 199 vd->vdev_ops->vdev_op_type) == 0); 200 if (!isspare) 201 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id) 202 == 0); 203 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0); 204 205 if (vd->vdev_path != NULL) 206 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PATH, 207 vd->vdev_path) == 0); 208 209 if (vd->vdev_devid != NULL) 210 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_DEVID, 211 vd->vdev_devid) == 0); 212 213 if (vd->vdev_physpath != NULL) 214 VERIFY(nvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH, 215 vd->vdev_physpath) == 0); 216 217 if (vd->vdev_nparity != 0) { 218 ASSERT(strcmp(vd->vdev_ops->vdev_op_type, 219 VDEV_TYPE_RAIDZ) == 0); 220 221 /* 222 * Make sure someone hasn't managed to sneak a fancy new vdev 223 * into a crufty old storage pool. 224 */ 225 ASSERT(vd->vdev_nparity == 1 || 226 (vd->vdev_nparity == 2 && 227 spa_version(spa) >= SPA_VERSION_RAID6)); 228 229 /* 230 * Note that we'll add the nparity tag even on storage pools 231 * that only support a single parity device -- older software 232 * will just ignore it. 233 */ 234 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, 235 vd->vdev_nparity) == 0); 236 } 237 238 if (vd->vdev_wholedisk != -1ULL) 239 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK, 240 vd->vdev_wholedisk) == 0); 241 242 if (vd->vdev_not_present) 243 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1) == 0); 244 245 if (vd->vdev_isspare) 246 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1) == 0); 247 248 if (!isspare && vd == vd->vdev_top) { 249 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY, 250 vd->vdev_ms_array) == 0); 251 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT, 252 vd->vdev_ms_shift) == 0); 253 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, 254 vd->vdev_ashift) == 0); 255 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE, 256 vd->vdev_asize) == 0); 257 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, 258 vd->vdev_islog) == 0); 259 } 260 261 if (vd->vdev_dtl.smo_object != 0) 262 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DTL, 263 vd->vdev_dtl.smo_object) == 0); 264 265 if (getstats) { 266 vdev_stat_t vs; 267 vdev_get_stats(vd, &vs); 268 VERIFY(nvlist_add_uint64_array(nv, ZPOOL_CONFIG_STATS, 269 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t)) == 0); 270 } 271 272 if (!vd->vdev_ops->vdev_op_leaf) { 273 nvlist_t **child; 274 int c; 275 276 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *), 277 KM_SLEEP); 278 279 for (c = 0; c < vd->vdev_children; c++) 280 child[c] = vdev_config_generate(spa, vd->vdev_child[c], 281 getstats, isspare); 282 283 VERIFY(nvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN, 284 child, vd->vdev_children) == 0); 285 286 for (c = 0; c < vd->vdev_children; c++) 287 nvlist_free(child[c]); 288 289 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *)); 290 291 } else { 292 if (vd->vdev_offline && !vd->vdev_tmpoffline) 293 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE, 294 B_TRUE) == 0); 295 if (vd->vdev_faulted) 296 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, 297 B_TRUE) == 0); 298 if (vd->vdev_degraded) 299 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, 300 B_TRUE) == 0); 301 if (vd->vdev_removed) 302 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, 303 B_TRUE) == 0); 304 if (vd->vdev_unspare) 305 VERIFY(nvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, 306 B_TRUE) == 0); 307 } 308 309 return (nv); 310 } 311 312 nvlist_t * 313 vdev_label_read_config(vdev_t *vd) 314 { 315 spa_t *spa = vd->vdev_spa; 316 nvlist_t *config = NULL; 317 vdev_phys_t *vp; 318 zio_t *zio; 319 int l; 320 321 ASSERT(spa_config_held(spa, RW_READER) || 322 spa_config_held(spa, RW_WRITER)); 323 324 if (vdev_is_dead(vd)) 325 return (NULL); 326 327 vp = zio_buf_alloc(sizeof (vdev_phys_t)); 328 329 for (l = 0; l < VDEV_LABELS; l++) { 330 331 zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL | 332 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_CONFIG_HELD); 333 334 vdev_label_read(zio, vd, l, vp, 335 offsetof(vdev_label_t, vl_vdev_phys), 336 sizeof (vdev_phys_t), NULL, NULL); 337 338 if (zio_wait(zio) == 0 && 339 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist), 340 &config, 0) == 0) 341 break; 342 343 if (config != NULL) { 344 nvlist_free(config); 345 config = NULL; 346 } 347 } 348 349 zio_buf_free(vp, sizeof (vdev_phys_t)); 350 351 return (config); 352 } 353 354 /* 355 * Determine if a device is in use. The 'spare_guid' parameter will be filled 356 * in with the device guid if this spare is active elsewhere on the system. 357 */ 358 static boolean_t 359 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason, 360 uint64_t *spare_guid) 361 { 362 spa_t *spa = vd->vdev_spa; 363 uint64_t state, pool_guid, device_guid, txg, spare_pool; 364 uint64_t vdtxg = 0; 365 nvlist_t *label; 366 367 if (spare_guid) 368 *spare_guid = 0ULL; 369 370 /* 371 * Read the label, if any, and perform some basic sanity checks. 372 */ 373 if ((label = vdev_label_read_config(vd)) == NULL) 374 return (B_FALSE); 375 376 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG, 377 &vdtxg); 378 379 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, 380 &state) != 0 || 381 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, 382 &device_guid) != 0) { 383 nvlist_free(label); 384 return (B_FALSE); 385 } 386 387 if (state != POOL_STATE_SPARE && 388 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID, 389 &pool_guid) != 0 || 390 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG, 391 &txg) != 0)) { 392 nvlist_free(label); 393 return (B_FALSE); 394 } 395 396 nvlist_free(label); 397 398 /* 399 * Check to see if this device indeed belongs to the pool it claims to 400 * be a part of. The only way this is allowed is if the device is a hot 401 * spare (which we check for later on). 402 */ 403 if (state != POOL_STATE_SPARE && 404 !spa_guid_exists(pool_guid, device_guid) && 405 !spa_spare_exists(device_guid, NULL)) 406 return (B_FALSE); 407 408 /* 409 * If the transaction group is zero, then this an initialized (but 410 * unused) label. This is only an error if the create transaction 411 * on-disk is the same as the one we're using now, in which case the 412 * user has attempted to add the same vdev multiple times in the same 413 * transaction. 414 */ 415 if (state != POOL_STATE_SPARE && txg == 0 && vdtxg == crtxg) 416 return (B_TRUE); 417 418 /* 419 * Check to see if this is a spare device. We do an explicit check for 420 * spa_has_spare() here because it may be on our pending list of spares 421 * to add. 422 */ 423 if (spa_spare_exists(device_guid, &spare_pool) || 424 spa_has_spare(spa, device_guid)) { 425 if (spare_guid) 426 *spare_guid = device_guid; 427 428 switch (reason) { 429 case VDEV_LABEL_CREATE: 430 return (B_TRUE); 431 432 case VDEV_LABEL_REPLACE: 433 return (!spa_has_spare(spa, device_guid) || 434 spare_pool != 0ULL); 435 436 case VDEV_LABEL_SPARE: 437 return (spa_has_spare(spa, device_guid)); 438 } 439 } 440 441 /* 442 * If the device is marked ACTIVE, then this device is in use by another 443 * pool on the system. 444 */ 445 return (state == POOL_STATE_ACTIVE); 446 } 447 448 /* 449 * Initialize a vdev label. We check to make sure each leaf device is not in 450 * use, and writable. We put down an initial label which we will later 451 * overwrite with a complete label. Note that it's important to do this 452 * sequentially, not in parallel, so that we catch cases of multiple use of the 453 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with 454 * itself. 455 */ 456 int 457 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason) 458 { 459 spa_t *spa = vd->vdev_spa; 460 nvlist_t *label; 461 vdev_phys_t *vp; 462 vdev_boot_header_t *vb; 463 uberblock_t *ub; 464 zio_t *zio; 465 int l, c, n; 466 char *buf; 467 size_t buflen; 468 int error; 469 uint64_t spare_guid; 470 471 ASSERT(spa_config_held(spa, RW_WRITER)); 472 473 for (c = 0; c < vd->vdev_children; c++) 474 if ((error = vdev_label_init(vd->vdev_child[c], 475 crtxg, reason)) != 0) 476 return (error); 477 478 if (!vd->vdev_ops->vdev_op_leaf) 479 return (0); 480 481 /* 482 * Dead vdevs cannot be initialized. 483 */ 484 if (vdev_is_dead(vd)) 485 return (EIO); 486 487 /* 488 * Determine if the vdev is in use. 489 */ 490 if (reason != VDEV_LABEL_REMOVE && 491 vdev_inuse(vd, crtxg, reason, &spare_guid)) 492 return (EBUSY); 493 494 ASSERT(reason != VDEV_LABEL_REMOVE || 495 vdev_inuse(vd, crtxg, reason, NULL)); 496 497 /* 498 * If this is a request to add or replace a spare that is in use 499 * elsewhere on the system, then we must update the guid (which was 500 * initialized to a random value) to reflect the actual GUID (which is 501 * shared between multiple pools). 502 */ 503 if (reason != VDEV_LABEL_REMOVE && spare_guid != 0ULL) { 504 vdev_t *pvd = vd->vdev_parent; 505 506 for (; pvd != NULL; pvd = pvd->vdev_parent) { 507 pvd->vdev_guid_sum -= vd->vdev_guid; 508 pvd->vdev_guid_sum += spare_guid; 509 } 510 511 vd->vdev_guid = vd->vdev_guid_sum = spare_guid; 512 513 /* 514 * If this is a replacement, then we want to fallthrough to the 515 * rest of the code. If we're adding a spare, then it's already 516 * labeled appropriately and we can just return. 517 */ 518 if (reason == VDEV_LABEL_SPARE) 519 return (0); 520 ASSERT(reason == VDEV_LABEL_REPLACE); 521 } 522 523 /* 524 * Initialize its label. 525 */ 526 vp = zio_buf_alloc(sizeof (vdev_phys_t)); 527 bzero(vp, sizeof (vdev_phys_t)); 528 529 /* 530 * Generate a label describing the pool and our top-level vdev. 531 * We mark it as being from txg 0 to indicate that it's not 532 * really part of an active pool just yet. The labels will 533 * be written again with a meaningful txg by spa_sync(). 534 */ 535 if (reason == VDEV_LABEL_SPARE || 536 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) { 537 /* 538 * For inactive hot spares, we generate a special label that 539 * identifies as a mutually shared hot spare. We write the 540 * label if we are adding a hot spare, or if we are removing an 541 * active hot spare (in which case we want to revert the 542 * labels). 543 */ 544 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0); 545 546 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION, 547 spa_version(spa)) == 0); 548 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE, 549 POOL_STATE_SPARE) == 0); 550 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID, 551 vd->vdev_guid) == 0); 552 } else { 553 label = spa_config_generate(spa, vd, 0ULL, B_FALSE); 554 555 /* 556 * Add our creation time. This allows us to detect multiple 557 * vdev uses as described above, and automatically expires if we 558 * fail. 559 */ 560 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG, 561 crtxg) == 0); 562 } 563 564 buf = vp->vp_nvlist; 565 buflen = sizeof (vp->vp_nvlist); 566 567 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP); 568 if (error != 0) { 569 nvlist_free(label); 570 zio_buf_free(vp, sizeof (vdev_phys_t)); 571 /* EFAULT means nvlist_pack ran out of room */ 572 return (error == EFAULT ? ENAMETOOLONG : EINVAL); 573 } 574 575 /* 576 * Initialize boot block header. 577 */ 578 vb = zio_buf_alloc(sizeof (vdev_boot_header_t)); 579 bzero(vb, sizeof (vdev_boot_header_t)); 580 vb->vb_magic = VDEV_BOOT_MAGIC; 581 vb->vb_version = VDEV_BOOT_VERSION; 582 vb->vb_offset = VDEV_BOOT_OFFSET; 583 vb->vb_size = VDEV_BOOT_SIZE; 584 585 /* 586 * Initialize uberblock template. 587 */ 588 ub = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)); 589 bzero(ub, VDEV_UBERBLOCK_SIZE(vd)); 590 *ub = spa->spa_uberblock; 591 ub->ub_txg = 0; 592 593 /* 594 * Write everything in parallel. 595 */ 596 zio = zio_root(spa, NULL, NULL, 597 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 598 599 for (l = 0; l < VDEV_LABELS; l++) { 600 601 vdev_label_write(zio, vd, l, vp, 602 offsetof(vdev_label_t, vl_vdev_phys), 603 sizeof (vdev_phys_t), NULL, NULL); 604 605 vdev_label_write(zio, vd, l, vb, 606 offsetof(vdev_label_t, vl_boot_header), 607 sizeof (vdev_boot_header_t), NULL, NULL); 608 609 for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) { 610 vdev_label_write(zio, vd, l, ub, 611 VDEV_UBERBLOCK_OFFSET(vd, n), 612 VDEV_UBERBLOCK_SIZE(vd), NULL, NULL); 613 } 614 } 615 616 error = zio_wait(zio); 617 618 nvlist_free(label); 619 zio_buf_free(ub, VDEV_UBERBLOCK_SIZE(vd)); 620 zio_buf_free(vb, sizeof (vdev_boot_header_t)); 621 zio_buf_free(vp, sizeof (vdev_phys_t)); 622 623 /* 624 * If this vdev hasn't been previously identified as a spare, then we 625 * mark it as such only if a) we are labeling it as a spare, or b) it 626 * exists as a spare elsewhere in the system. 627 */ 628 if (error == 0 && !vd->vdev_isspare && 629 (reason == VDEV_LABEL_SPARE || 630 spa_spare_exists(vd->vdev_guid, NULL))) 631 spa_spare_add(vd); 632 633 return (error); 634 } 635 636 /* 637 * ========================================================================== 638 * uberblock load/sync 639 * ========================================================================== 640 */ 641 642 /* 643 * Consider the following situation: txg is safely synced to disk. We've 644 * written the first uberblock for txg + 1, and then we lose power. When we 645 * come back up, we fail to see the uberblock for txg + 1 because, say, 646 * it was on a mirrored device and the replica to which we wrote txg + 1 647 * is now offline. If we then make some changes and sync txg + 1, and then 648 * the missing replica comes back, then for a new seconds we'll have two 649 * conflicting uberblocks on disk with the same txg. The solution is simple: 650 * among uberblocks with equal txg, choose the one with the latest timestamp. 651 */ 652 static int 653 vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2) 654 { 655 if (ub1->ub_txg < ub2->ub_txg) 656 return (-1); 657 if (ub1->ub_txg > ub2->ub_txg) 658 return (1); 659 660 if (ub1->ub_timestamp < ub2->ub_timestamp) 661 return (-1); 662 if (ub1->ub_timestamp > ub2->ub_timestamp) 663 return (1); 664 665 return (0); 666 } 667 668 static void 669 vdev_uberblock_load_done(zio_t *zio) 670 { 671 uberblock_t *ub = zio->io_data; 672 uberblock_t *ubbest = zio->io_private; 673 spa_t *spa = zio->io_spa; 674 675 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(zio->io_vd)); 676 677 if (zio->io_error == 0 && uberblock_verify(ub) == 0) { 678 mutex_enter(&spa->spa_uberblock_lock); 679 if (vdev_uberblock_compare(ub, ubbest) > 0) 680 *ubbest = *ub; 681 mutex_exit(&spa->spa_uberblock_lock); 682 } 683 684 zio_buf_free(zio->io_data, zio->io_size); 685 } 686 687 void 688 vdev_uberblock_load(zio_t *zio, vdev_t *vd, uberblock_t *ubbest) 689 { 690 int l, c, n; 691 692 for (c = 0; c < vd->vdev_children; c++) 693 vdev_uberblock_load(zio, vd->vdev_child[c], ubbest); 694 695 if (!vd->vdev_ops->vdev_op_leaf) 696 return; 697 698 if (vdev_is_dead(vd)) 699 return; 700 701 for (l = 0; l < VDEV_LABELS; l++) { 702 for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) { 703 vdev_label_read(zio, vd, l, 704 zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)), 705 VDEV_UBERBLOCK_OFFSET(vd, n), 706 VDEV_UBERBLOCK_SIZE(vd), 707 vdev_uberblock_load_done, ubbest); 708 } 709 } 710 } 711 712 /* 713 * Write the uberblock to both labels of all leaves of the specified vdev. 714 * We only get credit for writes to known-visible vdevs; see spa_vdev_add(). 715 */ 716 static void 717 vdev_uberblock_sync_done(zio_t *zio) 718 { 719 uint64_t *good_writes = zio->io_root->io_private; 720 721 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0) 722 atomic_add_64(good_writes, 1); 723 } 724 725 static void 726 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, uint64_t txg) 727 { 728 int l, c, n; 729 730 for (c = 0; c < vd->vdev_children; c++) 731 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], txg); 732 733 if (!vd->vdev_ops->vdev_op_leaf) 734 return; 735 736 if (vdev_is_dead(vd)) 737 return; 738 739 n = txg & (VDEV_UBERBLOCK_COUNT(vd) - 1); 740 741 ASSERT(ub->ub_txg == txg); 742 743 for (l = 0; l < VDEV_LABELS; l++) 744 vdev_label_write(zio, vd, l, ub, 745 VDEV_UBERBLOCK_OFFSET(vd, n), 746 VDEV_UBERBLOCK_SIZE(vd), 747 vdev_uberblock_sync_done, NULL); 748 749 dprintf("vdev %s in txg %llu\n", vdev_description(vd), txg); 750 } 751 752 static int 753 vdev_uberblock_sync_tree(spa_t *spa, uberblock_t *ub, vdev_t *vd, uint64_t txg) 754 { 755 uberblock_t *ubbuf; 756 size_t size = vd->vdev_top ? VDEV_UBERBLOCK_SIZE(vd) : SPA_MAXBLOCKSIZE; 757 uint64_t *good_writes; 758 zio_t *zio; 759 int error; 760 761 ubbuf = zio_buf_alloc(size); 762 bzero(ubbuf, size); 763 *ubbuf = *ub; 764 765 good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP); 766 767 zio = zio_root(spa, NULL, good_writes, 768 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 769 770 vdev_uberblock_sync(zio, ubbuf, vd, txg); 771 772 error = zio_wait(zio); 773 774 if (error && *good_writes != 0) { 775 dprintf("partial success: good_writes = %llu\n", *good_writes); 776 error = 0; 777 } 778 779 /* 780 * It's possible to have no good writes and no error if every vdev is in 781 * the CANT_OPEN state. 782 */ 783 if (*good_writes == 0 && error == 0) 784 error = EIO; 785 786 kmem_free(good_writes, sizeof (uint64_t)); 787 zio_buf_free(ubbuf, size); 788 789 return (error); 790 } 791 792 /* 793 * Sync out an individual vdev. 794 */ 795 static void 796 vdev_sync_label_done(zio_t *zio) 797 { 798 uint64_t *good_writes = zio->io_root->io_private; 799 800 if (zio->io_error == 0) 801 atomic_add_64(good_writes, 1); 802 } 803 804 static void 805 vdev_sync_label(zio_t *zio, vdev_t *vd, int l, uint64_t txg) 806 { 807 nvlist_t *label; 808 vdev_phys_t *vp; 809 char *buf; 810 size_t buflen; 811 int c; 812 813 for (c = 0; c < vd->vdev_children; c++) 814 vdev_sync_label(zio, vd->vdev_child[c], l, txg); 815 816 if (!vd->vdev_ops->vdev_op_leaf) 817 return; 818 819 if (vdev_is_dead(vd)) 820 return; 821 822 /* 823 * Generate a label describing the top-level config to which we belong. 824 */ 825 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE); 826 827 vp = zio_buf_alloc(sizeof (vdev_phys_t)); 828 bzero(vp, sizeof (vdev_phys_t)); 829 830 buf = vp->vp_nvlist; 831 buflen = sizeof (vp->vp_nvlist); 832 833 if (nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP) == 0) 834 vdev_label_write(zio, vd, l, vp, 835 offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t), 836 vdev_sync_label_done, NULL); 837 838 zio_buf_free(vp, sizeof (vdev_phys_t)); 839 nvlist_free(label); 840 841 dprintf("%s label %d txg %llu\n", vdev_description(vd), l, txg); 842 } 843 844 static int 845 vdev_sync_labels(vdev_t *vd, int l, uint64_t txg) 846 { 847 uint64_t *good_writes; 848 zio_t *zio; 849 int error; 850 851 ASSERT(vd == vd->vdev_top); 852 853 good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP); 854 855 zio = zio_root(vd->vdev_spa, NULL, good_writes, 856 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 857 858 /* 859 * Recursively kick off writes to all labels. 860 */ 861 vdev_sync_label(zio, vd, l, txg); 862 863 error = zio_wait(zio); 864 865 if (error && *good_writes != 0) { 866 dprintf("partial success: good_writes = %llu\n", *good_writes); 867 error = 0; 868 } 869 870 if (*good_writes == 0 && error == 0) 871 error = ENODEV; 872 873 /* 874 * Failure to write a label can be fatal for a 875 * top level vdev. We don't want this for slogs 876 * as we use the main pool if they go away. 877 */ 878 if (vd->vdev_islog) 879 error = 0; 880 881 kmem_free(good_writes, sizeof (uint64_t)); 882 883 return (error); 884 } 885 886 /* 887 * Sync the entire vdev configuration. 888 * 889 * The order of operations is carefully crafted to ensure that 890 * if the system panics or loses power at any time, the state on disk 891 * is still transactionally consistent. The in-line comments below 892 * describe the failure semantics at each stage. 893 * 894 * Moreover, it is designed to be idempotent: if spa_sync_labels() fails 895 * at any time, you can just call it again, and it will resume its work. 896 */ 897 int 898 vdev_config_sync(vdev_t *uvd, uint64_t txg) 899 { 900 spa_t *spa = uvd->vdev_spa; 901 uberblock_t *ub = &spa->spa_uberblock; 902 vdev_t *rvd = spa->spa_root_vdev; 903 vdev_t *vd; 904 zio_t *zio; 905 int l, error; 906 907 ASSERT(ub->ub_txg <= txg); 908 909 /* 910 * If this isn't a resync due to I/O errors, and nothing changed 911 * in this transaction group, and the vdev configuration hasn't changed, 912 * then there's nothing to do. 913 */ 914 if (ub->ub_txg < txg && uberblock_update(ub, rvd, txg) == B_FALSE && 915 list_is_empty(&spa->spa_dirty_list)) { 916 dprintf("nothing to sync in %s in txg %llu\n", 917 spa_name(spa), txg); 918 return (0); 919 } 920 921 if (txg > spa_freeze_txg(spa)) 922 return (0); 923 924 ASSERT(txg <= spa->spa_final_txg); 925 926 dprintf("syncing %s txg %llu\n", spa_name(spa), txg); 927 928 /* 929 * Flush the write cache of every disk that's been written to 930 * in this transaction group. This ensures that all blocks 931 * written in this txg will be committed to stable storage 932 * before any uberblock that references them. 933 */ 934 zio = zio_root(spa, NULL, NULL, 935 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 936 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd; 937 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg))) { 938 zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE, 939 NULL, NULL, ZIO_PRIORITY_NOW, 940 ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY)); 941 } 942 (void) zio_wait(zio); 943 944 /* 945 * Sync out the even labels (L0, L2) for every dirty vdev. If the 946 * system dies in the middle of this process, that's OK: all of the 947 * even labels that made it to disk will be newer than any uberblock, 948 * and will therefore be considered invalid. The odd labels (L1, L3), 949 * which have not yet been touched, will still be valid. 950 */ 951 for (vd = list_head(&spa->spa_dirty_list); vd != NULL; 952 vd = list_next(&spa->spa_dirty_list, vd)) { 953 for (l = 0; l < VDEV_LABELS; l++) { 954 if (l & 1) 955 continue; 956 if ((error = vdev_sync_labels(vd, l, txg)) != 0) 957 return (error); 958 } 959 } 960 961 /* 962 * Flush the new labels to disk. This ensures that all even-label 963 * updates are committed to stable storage before the uberblock update. 964 */ 965 zio = zio_root(spa, NULL, NULL, 966 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 967 for (vd = list_head(&spa->spa_dirty_list); vd != NULL; 968 vd = list_next(&spa->spa_dirty_list, vd)) { 969 zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE, 970 NULL, NULL, ZIO_PRIORITY_NOW, 971 ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY)); 972 } 973 (void) zio_wait(zio); 974 975 /* 976 * Sync the uberblocks to all vdevs in the tree specified by uvd. 977 * If the system dies in the middle of this step, there are two cases 978 * to consider, and the on-disk state is consistent either way: 979 * 980 * (1) If none of the new uberblocks made it to disk, then the 981 * previous uberblock will be the newest, and the odd labels 982 * (which had not yet been touched) will be valid with respect 983 * to that uberblock. 984 * 985 * (2) If one or more new uberblocks made it to disk, then they 986 * will be the newest, and the even labels (which had all 987 * been successfully committed) will be valid with respect 988 * to the new uberblocks. 989 */ 990 if ((error = vdev_uberblock_sync_tree(spa, ub, uvd, txg)) != 0) 991 return (error); 992 993 /* 994 * Flush the uberblocks to disk. This ensures that the odd labels 995 * are no longer needed (because the new uberblocks and the even 996 * labels are safely on disk), so it is safe to overwrite them. 997 */ 998 (void) zio_wait(zio_ioctl(NULL, spa, uvd, DKIOCFLUSHWRITECACHE, 999 NULL, NULL, ZIO_PRIORITY_NOW, 1000 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY)); 1001 1002 /* 1003 * Sync out odd labels for every dirty vdev. If the system dies 1004 * in the middle of this process, the even labels and the new 1005 * uberblocks will suffice to open the pool. The next time 1006 * the pool is opened, the first thing we'll do -- before any 1007 * user data is modified -- is mark every vdev dirty so that 1008 * all labels will be brought up to date. 1009 */ 1010 for (vd = list_head(&spa->spa_dirty_list); vd != NULL; 1011 vd = list_next(&spa->spa_dirty_list, vd)) { 1012 for (l = 0; l < VDEV_LABELS; l++) { 1013 if ((l & 1) == 0) 1014 continue; 1015 if ((error = vdev_sync_labels(vd, l, txg)) != 0) 1016 return (error); 1017 } 1018 } 1019 1020 /* 1021 * Flush the new labels to disk. This ensures that all odd-label 1022 * updates are committed to stable storage before the next 1023 * transaction group begins. 1024 */ 1025 zio = zio_root(spa, NULL, NULL, 1026 ZIO_FLAG_CONFIG_HELD | ZIO_FLAG_CANFAIL); 1027 for (vd = list_head(&spa->spa_dirty_list); vd != NULL; 1028 vd = list_next(&spa->spa_dirty_list, vd)) { 1029 zio_nowait(zio_ioctl(zio, spa, vd, DKIOCFLUSHWRITECACHE, 1030 NULL, NULL, ZIO_PRIORITY_NOW, 1031 ZIO_FLAG_CANFAIL | ZIO_FLAG_DONT_RETRY)); 1032 } 1033 (void) zio_wait(zio); 1034 1035 return (0); 1036 } 1037