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.
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.
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]
23 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Copyright (c) 2013 by Delphix. All rights reserved.
28 * Virtual Device Labels
29 * ---------------------
31 * The vdev label serves several distinct purposes:
33 * 1. Uniquely identify this device as part of a ZFS pool and confirm its
34 * identity within the pool.
36 * 2. Verify that all the devices given in a configuration are present
39 * 3. Determine the uberblock for the pool.
41 * 4. In case of an import operation, determine the configuration of the
42 * toplevel vdev of which it is a part.
44 * 5. If an import operation cannot find all the devices in the pool,
45 * provide enough information to the administrator to determine which
46 * devices are missing.
48 * It is important to note that while the kernel is responsible for writing the
49 * label, it only consumes the information in the first three cases. The
50 * latter information is only consumed in userland when determining the
51 * configuration to import a pool.
57 * Before describing the contents of the label, it's important to understand how
58 * the labels are written and updated with respect to the uberblock.
60 * When the pool configuration is altered, either because it was newly created
61 * or a device was added, we want to update all the labels such that we can deal
62 * with fatal failure at any point. To this end, each disk has two labels which
63 * are updated before and after the uberblock is synced. Assuming we have
64 * labels and an uberblock with the following transaction groups:
67 * +------+ +------+ +------+
69 * | t10 | | t10 | | t10 |
71 * +------+ +------+ +------+
73 * In this stable state, the labels and the uberblock were all updated within
74 * the same transaction group (10). Each label is mirrored and checksummed, so
75 * that we can detect when we fail partway through writing the label.
77 * In order to identify which labels are valid, the labels are written in the
80 * 1. For each vdev, update 'L1' to the new label
81 * 2. Update the uberblock
82 * 3. For each vdev, update 'L2' to the new label
84 * Given arbitrary failure, we can determine the correct label to use based on
85 * the transaction group. If we fail after updating L1 but before updating the
86 * UB, we will notice that L1's transaction group is greater than the uberblock,
87 * so L2 must be valid. If we fail after writing the uberblock but before
88 * writing L2, we will notice that L2's transaction group is less than L1, and
89 * therefore L1 is valid.
91 * Another added complexity is that not every label is updated when the config
92 * is synced. If we add a single device, we do not want to have to re-write
93 * every label for every device in the pool. This means that both L1 and L2 may
94 * be older than the pool uberblock, because the necessary information is stored
101 * The vdev label consists of two distinct parts, and is wrapped within the
102 * vdev_label_t structure. The label includes 8k of padding to permit legacy
103 * VTOC disk labels, but is otherwise ignored.
105 * The first half of the label is a packed nvlist which contains pool wide
106 * properties, per-vdev properties, and configuration information. It is
107 * described in more detail below.
109 * The latter half of the label consists of a redundant array of uberblocks.
110 * These uberblocks are updated whenever a transaction group is committed,
111 * or when the configuration is updated. When a pool is loaded, we scan each
112 * vdev for the 'best' uberblock.
115 * Configuration Information
116 * -------------------------
118 * The nvlist describing the pool and vdev contains the following elements:
120 * version ZFS on-disk version
123 * txg Transaction group in which this label was written
124 * pool_guid Unique identifier for this pool
125 * vdev_tree An nvlist describing vdev tree.
127 * An nvlist of the features necessary for reading the MOS.
129 * Each leaf device label also contains the following:
131 * top_guid Unique ID for top-level vdev in which this is contained
132 * guid Unique ID for the leaf vdev
134 * The 'vs' configuration follows the format described in 'spa_config.c'.
137 #include <sys/zfs_context.h>
139 #include <sys/spa_impl.h>
142 #include <sys/vdev.h>
143 #include <sys/vdev_impl.h>
144 #include <sys/uberblock_impl.h>
145 #include <sys/metaslab.h>
147 #include <sys/dsl_scan.h>
148 #include <sys/fs/zfs.h>
151 * Basic routines to read and write from a vdev label.
152 * Used throughout the rest of this file.
155 vdev_label_offset(uint64_t psize, int l, uint64_t offset)
157 ASSERT(offset < sizeof (vdev_label_t));
158 ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0);
160 return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ?
161 0 : psize - VDEV_LABELS * sizeof (vdev_label_t)));
165 * Returns back the vdev label associated with the passed in offset.
168 vdev_label_number(uint64_t psize, uint64_t offset)
172 if (offset >= psize - VDEV_LABEL_END_SIZE) {
173 offset -= psize - VDEV_LABEL_END_SIZE;
174 offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t);
176 l = offset / sizeof (vdev_label_t);
177 return (l < VDEV_LABELS ? l : -1);
181 vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
182 uint64_t size, zio_done_func_t *done, void *private, int flags)
184 ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) ==
186 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
188 zio_nowait(zio_read_phys(zio, vd,
189 vdev_label_offset(vd->vdev_psize, l, offset),
190 size, buf, ZIO_CHECKSUM_LABEL, done, private,
191 ZIO_PRIORITY_SYNC_READ, flags, B_TRUE));
195 vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset,
196 uint64_t size, zio_done_func_t *done, void *private, int flags)
198 ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL ||
199 (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) ==
200 (SCL_CONFIG | SCL_STATE) &&
201 dsl_pool_sync_context(spa_get_dsl(zio->io_spa))));
202 ASSERT(flags & ZIO_FLAG_CONFIG_WRITER);
204 zio_nowait(zio_write_phys(zio, vd,
205 vdev_label_offset(vd->vdev_psize, l, offset),
206 size, buf, ZIO_CHECKSUM_LABEL, done, private,
207 ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE));
211 * Generate the nvlist representing this vdev's config.
214 vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
215 vdev_config_flag_t flags)
219 VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
221 fnvlist_add_string(nv, ZPOOL_CONFIG_TYPE, vd->vdev_ops->vdev_op_type);
222 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)))
223 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id);
224 fnvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid);
226 if (vd->vdev_path != NULL)
227 fnvlist_add_string(nv, ZPOOL_CONFIG_PATH, vd->vdev_path);
229 if (vd->vdev_devid != NULL)
230 fnvlist_add_string(nv, ZPOOL_CONFIG_DEVID, vd->vdev_devid);
232 if (vd->vdev_physpath != NULL)
233 fnvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH,
236 if (vd->vdev_fru != NULL)
237 fnvlist_add_string(nv, ZPOOL_CONFIG_FRU, vd->vdev_fru);
239 if (vd->vdev_nparity != 0) {
240 ASSERT(strcmp(vd->vdev_ops->vdev_op_type,
241 VDEV_TYPE_RAIDZ) == 0);
244 * Make sure someone hasn't managed to sneak a fancy new vdev
245 * into a crufty old storage pool.
247 ASSERT(vd->vdev_nparity == 1 ||
248 (vd->vdev_nparity <= 2 &&
249 spa_version(spa) >= SPA_VERSION_RAIDZ2) ||
250 (vd->vdev_nparity <= 3 &&
251 spa_version(spa) >= SPA_VERSION_RAIDZ3));
254 * Note that we'll add the nparity tag even on storage pools
255 * that only support a single parity device -- older software
256 * will just ignore it.
258 fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vd->vdev_nparity);
261 if (vd->vdev_wholedisk != -1ULL)
262 fnvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
265 if (vd->vdev_not_present)
266 fnvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1);
268 if (vd->vdev_isspare)
269 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1);
271 if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) &&
272 vd == vd->vdev_top) {
273 fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
275 fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
277 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift);
278 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE,
280 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, vd->vdev_islog);
281 if (vd->vdev_removing)
282 fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING,
286 if (vd->vdev_dtl_smo.smo_object != 0)
287 fnvlist_add_uint64(nv, ZPOOL_CONFIG_DTL,
288 vd->vdev_dtl_smo.smo_object);
291 fnvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG, vd->vdev_crtxg);
297 vdev_get_stats(vd, &vs);
298 fnvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS,
299 (uint64_t *)&vs, sizeof (vs) / sizeof (uint64_t));
301 /* provide either current or previous scan information */
302 if (spa_scan_get_stats(spa, &ps) == 0) {
303 fnvlist_add_uint64_array(nv,
304 ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps,
305 sizeof (pool_scan_stat_t) / sizeof (uint64_t));
309 if (!vd->vdev_ops->vdev_op_leaf) {
313 ASSERT(!vd->vdev_ishole);
315 child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *),
318 for (c = 0, idx = 0; c < vd->vdev_children; c++) {
319 vdev_t *cvd = vd->vdev_child[c];
322 * If we're generating an nvlist of removing
323 * vdevs then skip over any device which is
326 if ((flags & VDEV_CONFIG_REMOVING) &&
330 child[idx++] = vdev_config_generate(spa, cvd,
335 fnvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
339 for (c = 0; c < idx; c++)
340 nvlist_free(child[c]);
342 kmem_free(child, vd->vdev_children * sizeof (nvlist_t *));
345 const char *aux = NULL;
347 if (vd->vdev_offline && !vd->vdev_tmpoffline)
348 fnvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE, B_TRUE);
349 if (vd->vdev_resilver_txg != 0)
350 fnvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
351 vd->vdev_resilver_txg);
352 if (vd->vdev_faulted)
353 fnvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, B_TRUE);
354 if (vd->vdev_degraded)
355 fnvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, B_TRUE);
356 if (vd->vdev_removed)
357 fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, B_TRUE);
358 if (vd->vdev_unspare)
359 fnvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, B_TRUE);
361 fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE, B_TRUE);
363 switch (vd->vdev_stat.vs_aux) {
364 case VDEV_AUX_ERR_EXCEEDED:
365 aux = "err_exceeded";
368 case VDEV_AUX_EXTERNAL:
374 fnvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE, aux);
376 if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) {
377 fnvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID,
386 * Generate a view of the top-level vdevs. If we currently have holes
387 * in the namespace, then generate an array which contains a list of holey
388 * vdevs. Additionally, add the number of top-level children that currently
392 vdev_top_config_generate(spa_t *spa, nvlist_t *config)
394 vdev_t *rvd = spa->spa_root_vdev;
398 array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_PUSHPAGE);
400 for (c = 0, idx = 0; c < rvd->vdev_children; c++) {
401 vdev_t *tvd = rvd->vdev_child[c];
403 if (tvd->vdev_ishole)
408 VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY,
412 VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
413 rvd->vdev_children) == 0);
415 kmem_free(array, rvd->vdev_children * sizeof (uint64_t));
419 * Returns the configuration from the label of the given vdev. For vdevs
420 * which don't have a txg value stored on their label (i.e. spares/cache)
421 * or have not been completely initialized (txg = 0) just return
422 * the configuration from the first valid label we find. Otherwise,
423 * find the most up-to-date label that does not exceed the specified
427 vdev_label_read_config(vdev_t *vd, uint64_t txg)
429 spa_t *spa = vd->vdev_spa;
430 nvlist_t *config = NULL;
433 uint64_t best_txg = 0;
435 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
436 ZIO_FLAG_SPECULATIVE;
439 ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
441 if (!vdev_readable(vd))
444 vp = zio_buf_alloc(sizeof (vdev_phys_t));
447 for (l = 0; l < VDEV_LABELS; l++) {
448 nvlist_t *label = NULL;
450 zio = zio_root(spa, NULL, NULL, flags);
452 vdev_label_read(zio, vd, l, vp,
453 offsetof(vdev_label_t, vl_vdev_phys),
454 sizeof (vdev_phys_t), NULL, NULL, flags);
456 if (zio_wait(zio) == 0 &&
457 nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist),
459 uint64_t label_txg = 0;
462 * Auxiliary vdevs won't have txg values in their
463 * labels and newly added vdevs may not have been
464 * completely initialized so just return the
465 * configuration from the first valid label we
468 error = nvlist_lookup_uint64(label,
469 ZPOOL_CONFIG_POOL_TXG, &label_txg);
470 if ((error || label_txg == 0) && !config) {
473 } else if (label_txg <= txg && label_txg > best_txg) {
474 best_txg = label_txg;
476 config = fnvlist_dup(label);
486 if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) {
487 flags |= ZIO_FLAG_TRYHARD;
491 zio_buf_free(vp, sizeof (vdev_phys_t));
497 * Determine if a device is in use. The 'spare_guid' parameter will be filled
498 * in with the device guid if this spare is active elsewhere on the system.
501 vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason,
502 uint64_t *spare_guid, uint64_t *l2cache_guid)
504 spa_t *spa = vd->vdev_spa;
505 uint64_t state, pool_guid, device_guid, txg, spare_pool;
512 *l2cache_guid = 0ULL;
515 * Read the label, if any, and perform some basic sanity checks.
517 if ((label = vdev_label_read_config(vd, -1ULL)) == NULL)
520 (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
523 if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
525 nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
526 &device_guid) != 0) {
531 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
532 (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID,
534 nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG,
543 * Check to see if this device indeed belongs to the pool it claims to
544 * be a part of. The only way this is allowed is if the device is a hot
545 * spare (which we check for later on).
547 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
548 !spa_guid_exists(pool_guid, device_guid) &&
549 !spa_spare_exists(device_guid, NULL, NULL) &&
550 !spa_l2cache_exists(device_guid, NULL))
554 * If the transaction group is zero, then this an initialized (but
555 * unused) label. This is only an error if the create transaction
556 * on-disk is the same as the one we're using now, in which case the
557 * user has attempted to add the same vdev multiple times in the same
560 if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE &&
561 txg == 0 && vdtxg == crtxg)
565 * Check to see if this is a spare device. We do an explicit check for
566 * spa_has_spare() here because it may be on our pending list of spares
567 * to add. We also check if it is an l2cache device.
569 if (spa_spare_exists(device_guid, &spare_pool, NULL) ||
570 spa_has_spare(spa, device_guid)) {
572 *spare_guid = device_guid;
575 case VDEV_LABEL_CREATE:
576 case VDEV_LABEL_L2CACHE:
579 case VDEV_LABEL_REPLACE:
580 return (!spa_has_spare(spa, device_guid) ||
583 case VDEV_LABEL_SPARE:
584 return (spa_has_spare(spa, device_guid));
591 * Check to see if this is an l2cache device.
593 if (spa_l2cache_exists(device_guid, NULL))
597 * We can't rely on a pool's state if it's been imported
598 * read-only. Instead we look to see if the pools is marked
599 * read-only in the namespace and set the state to active.
601 if ((spa = spa_by_guid(pool_guid, device_guid)) != NULL &&
602 spa_mode(spa) == FREAD)
603 state = POOL_STATE_ACTIVE;
606 * If the device is marked ACTIVE, then this device is in use by another
607 * pool on the system.
609 return (state == POOL_STATE_ACTIVE);
613 * Initialize a vdev label. We check to make sure each leaf device is not in
614 * use, and writable. We put down an initial label which we will later
615 * overwrite with a complete label. Note that it's important to do this
616 * sequentially, not in parallel, so that we catch cases of multiple use of the
617 * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with
621 vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
623 spa_t *spa = vd->vdev_spa;
632 uint64_t spare_guid = 0, l2cache_guid = 0;
633 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
637 ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
639 for (c = 0; c < vd->vdev_children; c++)
640 if ((error = vdev_label_init(vd->vdev_child[c],
641 crtxg, reason)) != 0)
644 /* Track the creation time for this vdev */
645 vd->vdev_crtxg = crtxg;
647 if (!vd->vdev_ops->vdev_op_leaf || !spa_writeable(spa))
651 * Dead vdevs cannot be initialized.
653 if (vdev_is_dead(vd))
654 return (SET_ERROR(EIO));
657 * Determine if the vdev is in use.
659 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT &&
660 vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid))
661 return (SET_ERROR(EBUSY));
664 * If this is a request to add or replace a spare or l2cache device
665 * that is in use elsewhere on the system, then we must update the
666 * guid (which was initialized to a random value) to reflect the
667 * actual GUID (which is shared between multiple pools).
669 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE &&
670 spare_guid != 0ULL) {
671 uint64_t guid_delta = spare_guid - vd->vdev_guid;
673 vd->vdev_guid += guid_delta;
675 for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
676 pvd->vdev_guid_sum += guid_delta;
679 * If this is a replacement, then we want to fallthrough to the
680 * rest of the code. If we're adding a spare, then it's already
681 * labeled appropriately and we can just return.
683 if (reason == VDEV_LABEL_SPARE)
685 ASSERT(reason == VDEV_LABEL_REPLACE ||
686 reason == VDEV_LABEL_SPLIT);
689 if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE &&
690 l2cache_guid != 0ULL) {
691 uint64_t guid_delta = l2cache_guid - vd->vdev_guid;
693 vd->vdev_guid += guid_delta;
695 for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent)
696 pvd->vdev_guid_sum += guid_delta;
699 * If this is a replacement, then we want to fallthrough to the
700 * rest of the code. If we're adding an l2cache, then it's
701 * already labeled appropriately and we can just return.
703 if (reason == VDEV_LABEL_L2CACHE)
705 ASSERT(reason == VDEV_LABEL_REPLACE);
709 * Initialize its label.
711 vp = zio_buf_alloc(sizeof (vdev_phys_t));
712 bzero(vp, sizeof (vdev_phys_t));
715 * Generate a label describing the pool and our top-level vdev.
716 * We mark it as being from txg 0 to indicate that it's not
717 * really part of an active pool just yet. The labels will
718 * be written again with a meaningful txg by spa_sync().
720 if (reason == VDEV_LABEL_SPARE ||
721 (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) {
723 * For inactive hot spares, we generate a special label that
724 * identifies as a mutually shared hot spare. We write the
725 * label if we are adding a hot spare, or if we are removing an
726 * active hot spare (in which case we want to revert the
729 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
731 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
732 spa_version(spa)) == 0);
733 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
734 POOL_STATE_SPARE) == 0);
735 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
736 vd->vdev_guid) == 0);
737 } else if (reason == VDEV_LABEL_L2CACHE ||
738 (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) {
740 * For level 2 ARC devices, add a special label.
742 VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
744 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION,
745 spa_version(spa)) == 0);
746 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE,
747 POOL_STATE_L2CACHE) == 0);
748 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
749 vd->vdev_guid) == 0);
753 if (reason == VDEV_LABEL_SPLIT)
754 txg = spa->spa_uberblock.ub_txg;
755 label = spa_config_generate(spa, vd, txg, B_FALSE);
758 * Add our creation time. This allows us to detect multiple
759 * vdev uses as described above, and automatically expires if we
762 VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG,
767 buflen = sizeof (vp->vp_nvlist);
769 error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_PUSHPAGE);
772 zio_buf_free(vp, sizeof (vdev_phys_t));
773 /* EFAULT means nvlist_pack ran out of room */
774 return (error == EFAULT ? ENAMETOOLONG : EINVAL);
778 * Initialize uberblock template.
780 ub = zio_buf_alloc(VDEV_UBERBLOCK_RING);
781 bzero(ub, VDEV_UBERBLOCK_RING);
782 *ub = spa->spa_uberblock;
785 /* Initialize the 2nd padding area. */
786 pad2 = zio_buf_alloc(VDEV_PAD_SIZE);
787 bzero(pad2, VDEV_PAD_SIZE);
790 * Write everything in parallel.
793 zio = zio_root(spa, NULL, NULL, flags);
795 for (l = 0; l < VDEV_LABELS; l++) {
797 vdev_label_write(zio, vd, l, vp,
798 offsetof(vdev_label_t, vl_vdev_phys),
799 sizeof (vdev_phys_t), NULL, NULL, flags);
802 * Skip the 1st padding area.
803 * Zero out the 2nd padding area where it might have
804 * left over data from previous filesystem format.
806 vdev_label_write(zio, vd, l, pad2,
807 offsetof(vdev_label_t, vl_pad2),
808 VDEV_PAD_SIZE, NULL, NULL, flags);
810 vdev_label_write(zio, vd, l, ub,
811 offsetof(vdev_label_t, vl_uberblock),
812 VDEV_UBERBLOCK_RING, NULL, NULL, flags);
815 error = zio_wait(zio);
817 if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) {
818 flags |= ZIO_FLAG_TRYHARD;
823 zio_buf_free(pad2, VDEV_PAD_SIZE);
824 zio_buf_free(ub, VDEV_UBERBLOCK_RING);
825 zio_buf_free(vp, sizeof (vdev_phys_t));
828 * If this vdev hasn't been previously identified as a spare, then we
829 * mark it as such only if a) we are labeling it as a spare, or b) it
830 * exists as a spare elsewhere in the system. Do the same for
831 * level 2 ARC devices.
833 if (error == 0 && !vd->vdev_isspare &&
834 (reason == VDEV_LABEL_SPARE ||
835 spa_spare_exists(vd->vdev_guid, NULL, NULL)))
838 if (error == 0 && !vd->vdev_isl2cache &&
839 (reason == VDEV_LABEL_L2CACHE ||
840 spa_l2cache_exists(vd->vdev_guid, NULL)))
847 * ==========================================================================
848 * uberblock load/sync
849 * ==========================================================================
853 * Consider the following situation: txg is safely synced to disk. We've
854 * written the first uberblock for txg + 1, and then we lose power. When we
855 * come back up, we fail to see the uberblock for txg + 1 because, say,
856 * it was on a mirrored device and the replica to which we wrote txg + 1
857 * is now offline. If we then make some changes and sync txg + 1, and then
858 * the missing replica comes back, then for a few seconds we'll have two
859 * conflicting uberblocks on disk with the same txg. The solution is simple:
860 * among uberblocks with equal txg, choose the one with the latest timestamp.
863 vdev_uberblock_compare(uberblock_t *ub1, uberblock_t *ub2)
865 if (ub1->ub_txg < ub2->ub_txg)
867 if (ub1->ub_txg > ub2->ub_txg)
870 if (ub1->ub_timestamp < ub2->ub_timestamp)
872 if (ub1->ub_timestamp > ub2->ub_timestamp)
879 uberblock_t *ubl_ubbest; /* Best uberblock */
880 vdev_t *ubl_vd; /* vdev associated with the above */
884 vdev_uberblock_load_done(zio_t *zio)
886 vdev_t *vd = zio->io_vd;
887 spa_t *spa = zio->io_spa;
888 zio_t *rio = zio->io_private;
889 uberblock_t *ub = zio->io_data;
890 struct ubl_cbdata *cbp = rio->io_private;
892 ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd));
894 if (zio->io_error == 0 && uberblock_verify(ub) == 0) {
895 mutex_enter(&rio->io_lock);
896 if (ub->ub_txg <= spa->spa_load_max_txg &&
897 vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) {
899 * Keep track of the vdev in which this uberblock
900 * was found. We will use this information later
901 * to obtain the config nvlist associated with
904 *cbp->ubl_ubbest = *ub;
907 mutex_exit(&rio->io_lock);
910 zio_buf_free(zio->io_data, zio->io_size);
914 vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags,
915 struct ubl_cbdata *cbp)
919 for (c = 0; c < vd->vdev_children; c++)
920 vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp);
922 if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
923 for (l = 0; l < VDEV_LABELS; l++) {
924 for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) {
925 vdev_label_read(zio, vd, l,
926 zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)),
927 VDEV_UBERBLOCK_OFFSET(vd, n),
928 VDEV_UBERBLOCK_SIZE(vd),
929 vdev_uberblock_load_done, zio, flags);
936 * Reads the 'best' uberblock from disk along with its associated
937 * configuration. First, we read the uberblock array of each label of each
938 * vdev, keeping track of the uberblock with the highest txg in each array.
939 * Then, we read the configuration from the same vdev as the best uberblock.
942 vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config)
945 spa_t *spa = rvd->vdev_spa;
946 struct ubl_cbdata cb;
947 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL |
948 ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD;
953 bzero(ub, sizeof (uberblock_t));
959 spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
960 zio = zio_root(spa, NULL, &cb, flags);
961 vdev_uberblock_load_impl(zio, rvd, flags, &cb);
962 (void) zio_wait(zio);
965 * It's possible that the best uberblock was discovered on a label
966 * that has a configuration which was written in a future txg.
967 * Search all labels on this vdev to find the configuration that
968 * matches the txg for our uberblock.
970 if (cb.ubl_vd != NULL)
971 *config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg);
972 spa_config_exit(spa, SCL_ALL, FTAG);
976 * On success, increment root zio's count of good writes.
977 * We only get credit for writes to known-visible vdevs; see spa_vdev_add().
980 vdev_uberblock_sync_done(zio_t *zio)
982 uint64_t *good_writes = zio->io_private;
984 if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0)
985 atomic_add_64(good_writes, 1);
989 * Write the uberblock to all labels of all leaves of the specified vdev.
992 vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags)
997 for (c = 0; c < vd->vdev_children; c++)
998 vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags);
1000 if (!vd->vdev_ops->vdev_op_leaf)
1003 if (!vdev_writeable(vd))
1006 n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1);
1008 ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd));
1009 bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
1012 for (l = 0; l < VDEV_LABELS; l++)
1013 vdev_label_write(zio, vd, l, ubbuf,
1014 VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd),
1015 vdev_uberblock_sync_done, zio->io_private,
1016 flags | ZIO_FLAG_DONT_PROPAGATE);
1018 zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd));
1021 /* Sync the uberblocks to all vdevs in svd[] */
1023 vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags)
1025 spa_t *spa = svd[0]->vdev_spa;
1027 uint64_t good_writes = 0;
1030 zio = zio_root(spa, NULL, &good_writes, flags);
1032 for (v = 0; v < svdcount; v++)
1033 vdev_uberblock_sync(zio, ub, svd[v], flags);
1035 (void) zio_wait(zio);
1038 * Flush the uberblocks to disk. This ensures that the odd labels
1039 * are no longer needed (because the new uberblocks and the even
1040 * labels are safely on disk), so it is safe to overwrite them.
1042 zio = zio_root(spa, NULL, NULL, flags);
1044 for (v = 0; v < svdcount; v++)
1045 zio_flush(zio, svd[v]);
1047 (void) zio_wait(zio);
1049 return (good_writes >= 1 ? 0 : EIO);
1053 * On success, increment the count of good writes for our top-level vdev.
1056 vdev_label_sync_done(zio_t *zio)
1058 uint64_t *good_writes = zio->io_private;
1060 if (zio->io_error == 0)
1061 atomic_add_64(good_writes, 1);
1065 * If there weren't enough good writes, indicate failure to the parent.
1068 vdev_label_sync_top_done(zio_t *zio)
1070 uint64_t *good_writes = zio->io_private;
1072 if (*good_writes == 0)
1073 zio->io_error = SET_ERROR(EIO);
1075 kmem_free(good_writes, sizeof (uint64_t));
1079 * We ignore errors for log and cache devices, simply free the private data.
1082 vdev_label_sync_ignore_done(zio_t *zio)
1084 kmem_free(zio->io_private, sizeof (uint64_t));
1088 * Write all even or odd labels to all leaves of the specified vdev.
1091 vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags)
1099 for (c = 0; c < vd->vdev_children; c++)
1100 vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags);
1102 if (!vd->vdev_ops->vdev_op_leaf)
1105 if (!vdev_writeable(vd))
1109 * Generate a label describing the top-level config to which we belong.
1111 label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE);
1113 vp = zio_buf_alloc(sizeof (vdev_phys_t));
1114 bzero(vp, sizeof (vdev_phys_t));
1116 buf = vp->vp_nvlist;
1117 buflen = sizeof (vp->vp_nvlist);
1119 if (!nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_PUSHPAGE)) {
1120 for (; l < VDEV_LABELS; l += 2) {
1121 vdev_label_write(zio, vd, l, vp,
1122 offsetof(vdev_label_t, vl_vdev_phys),
1123 sizeof (vdev_phys_t),
1124 vdev_label_sync_done, zio->io_private,
1125 flags | ZIO_FLAG_DONT_PROPAGATE);
1129 zio_buf_free(vp, sizeof (vdev_phys_t));
1134 vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags)
1136 list_t *dl = &spa->spa_config_dirty_list;
1142 * Write the new labels to disk.
1144 zio = zio_root(spa, NULL, NULL, flags);
1146 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) {
1147 uint64_t *good_writes;
1150 ASSERT(!vd->vdev_ishole);
1152 good_writes = kmem_zalloc(sizeof (uint64_t), KM_PUSHPAGE);
1153 vio = zio_null(zio, spa, NULL,
1154 (vd->vdev_islog || vd->vdev_aux != NULL) ?
1155 vdev_label_sync_ignore_done : vdev_label_sync_top_done,
1156 good_writes, flags);
1157 vdev_label_sync(vio, vd, l, txg, flags);
1161 error = zio_wait(zio);
1164 * Flush the new labels to disk.
1166 zio = zio_root(spa, NULL, NULL, flags);
1168 for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd))
1171 (void) zio_wait(zio);
1177 * Sync the uberblock and any changes to the vdev configuration.
1179 * The order of operations is carefully crafted to ensure that
1180 * if the system panics or loses power at any time, the state on disk
1181 * is still transactionally consistent. The in-line comments below
1182 * describe the failure semantics at each stage.
1184 * Moreover, vdev_config_sync() is designed to be idempotent: if it fails
1185 * at any time, you can just call it again, and it will resume its work.
1188 vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg, boolean_t tryhard)
1190 spa_t *spa = svd[0]->vdev_spa;
1191 uberblock_t *ub = &spa->spa_uberblock;
1195 int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
1198 * Normally, we don't want to try too hard to write every label and
1199 * uberblock. If there is a flaky disk, we don't want the rest of the
1200 * sync process to block while we retry. But if we can't write a
1201 * single label out, we should retry with ZIO_FLAG_TRYHARD before
1202 * bailing out and declaring the pool faulted.
1205 flags |= ZIO_FLAG_TRYHARD;
1207 ASSERT(ub->ub_txg <= txg);
1210 * If this isn't a resync due to I/O errors,
1211 * and nothing changed in this transaction group,
1212 * and the vdev configuration hasn't changed,
1213 * then there's nothing to do.
1215 if (ub->ub_txg < txg &&
1216 uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE &&
1217 list_is_empty(&spa->spa_config_dirty_list))
1220 if (txg > spa_freeze_txg(spa))
1223 ASSERT(txg <= spa->spa_final_txg);
1226 * Flush the write cache of every disk that's been written to
1227 * in this transaction group. This ensures that all blocks
1228 * written in this txg will be committed to stable storage
1229 * before any uberblock that references them.
1231 zio = zio_root(spa, NULL, NULL, flags);
1233 for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd;
1234 vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg)))
1237 (void) zio_wait(zio);
1240 * Sync out the even labels (L0, L2) for every dirty vdev. If the
1241 * system dies in the middle of this process, that's OK: all of the
1242 * even labels that made it to disk will be newer than any uberblock,
1243 * and will therefore be considered invalid. The odd labels (L1, L3),
1244 * which have not yet been touched, will still be valid. We flush
1245 * the new labels to disk to ensure that all even-label updates
1246 * are committed to stable storage before the uberblock update.
1248 if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0)
1252 * Sync the uberblocks to all vdevs in svd[].
1253 * If the system dies in the middle of this step, there are two cases
1254 * to consider, and the on-disk state is consistent either way:
1256 * (1) If none of the new uberblocks made it to disk, then the
1257 * previous uberblock will be the newest, and the odd labels
1258 * (which had not yet been touched) will be valid with respect
1259 * to that uberblock.
1261 * (2) If one or more new uberblocks made it to disk, then they
1262 * will be the newest, and the even labels (which had all
1263 * been successfully committed) will be valid with respect
1264 * to the new uberblocks.
1266 if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0)
1270 * Sync out odd labels for every dirty vdev. If the system dies
1271 * in the middle of this process, the even labels and the new
1272 * uberblocks will suffice to open the pool. The next time
1273 * the pool is opened, the first thing we'll do -- before any
1274 * user data is modified -- is mark every vdev dirty so that
1275 * all labels will be brought up to date. We flush the new labels
1276 * to disk to ensure that all odd-label updates are committed to
1277 * stable storage before the next transaction group begins.
1279 return (vdev_label_sync_list(spa, 1, txg, flags));