/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2013 by Delphix. All rights reserved. */ /* * Virtual Device Labels * --------------------- * * The vdev label serves several distinct purposes: * * 1. Uniquely identify this device as part of a ZFS pool and confirm its * identity within the pool. * * 2. Verify that all the devices given in a configuration are present * within the pool. * * 3. Determine the uberblock for the pool. * * 4. In case of an import operation, determine the configuration of the * toplevel vdev of which it is a part. * * 5. If an import operation cannot find all the devices in the pool, * provide enough information to the administrator to determine which * devices are missing. * * It is important to note that while the kernel is responsible for writing the * label, it only consumes the information in the first three cases. The * latter information is only consumed in userland when determining the * configuration to import a pool. * * * Label Organization * ------------------ * * Before describing the contents of the label, it's important to understand how * the labels are written and updated with respect to the uberblock. * * When the pool configuration is altered, either because it was newly created * or a device was added, we want to update all the labels such that we can deal * with fatal failure at any point. To this end, each disk has two labels which * are updated before and after the uberblock is synced. Assuming we have * labels and an uberblock with the following transaction groups: * * L1 UB L2 * +------+ +------+ +------+ * | | | | | | * | t10 | | t10 | | t10 | * | | | | | | * +------+ +------+ +------+ * * In this stable state, the labels and the uberblock were all updated within * the same transaction group (10). Each label is mirrored and checksummed, so * that we can detect when we fail partway through writing the label. * * In order to identify which labels are valid, the labels are written in the * following manner: * * 1. For each vdev, update 'L1' to the new label * 2. Update the uberblock * 3. For each vdev, update 'L2' to the new label * * Given arbitrary failure, we can determine the correct label to use based on * the transaction group. If we fail after updating L1 but before updating the * UB, we will notice that L1's transaction group is greater than the uberblock, * so L2 must be valid. If we fail after writing the uberblock but before * writing L2, we will notice that L2's transaction group is less than L1, and * therefore L1 is valid. * * Another added complexity is that not every label is updated when the config * is synced. If we add a single device, we do not want to have to re-write * every label for every device in the pool. This means that both L1 and L2 may * be older than the pool uberblock, because the necessary information is stored * on another vdev. * * * On-disk Format * -------------- * * The vdev label consists of two distinct parts, and is wrapped within the * vdev_label_t structure. The label includes 8k of padding to permit legacy * VTOC disk labels, but is otherwise ignored. * * The first half of the label is a packed nvlist which contains pool wide * properties, per-vdev properties, and configuration information. It is * described in more detail below. * * The latter half of the label consists of a redundant array of uberblocks. * These uberblocks are updated whenever a transaction group is committed, * or when the configuration is updated. When a pool is loaded, we scan each * vdev for the 'best' uberblock. * * * Configuration Information * ------------------------- * * The nvlist describing the pool and vdev contains the following elements: * * version ZFS on-disk version * name Pool name * state Pool state * txg Transaction group in which this label was written * pool_guid Unique identifier for this pool * vdev_tree An nvlist describing vdev tree. * features_for_read * An nvlist of the features necessary for reading the MOS. * * Each leaf device label also contains the following: * * top_guid Unique ID for top-level vdev in which this is contained * guid Unique ID for the leaf vdev * * The 'vs' configuration follows the format described in 'spa_config.c'. */ #include #include #include #include #include #include #include #include #include #include #include #include /* * Basic routines to read and write from a vdev label. * Used throughout the rest of this file. */ uint64_t vdev_label_offset(uint64_t psize, int l, uint64_t offset) { ASSERT(offset < sizeof (vdev_label_t)); ASSERT(P2PHASE_TYPED(psize, sizeof (vdev_label_t), uint64_t) == 0); return (offset + l * sizeof (vdev_label_t) + (l < VDEV_LABELS / 2 ? 0 : psize - VDEV_LABELS * sizeof (vdev_label_t))); } /* * Returns back the vdev label associated with the passed in offset. */ int vdev_label_number(uint64_t psize, uint64_t offset) { int l; if (offset >= psize - VDEV_LABEL_END_SIZE) { offset -= psize - VDEV_LABEL_END_SIZE; offset += (VDEV_LABELS / 2) * sizeof (vdev_label_t); } l = offset / sizeof (vdev_label_t); return (l < VDEV_LABELS ? l : -1); } static void vdev_label_read(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset, uint64_t size, zio_done_func_t *done, void *private, int flags) { ASSERT(spa_config_held(zio->io_spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL); ASSERT(flags & ZIO_FLAG_CONFIG_WRITER); zio_nowait(zio_read_phys(zio, vd, vdev_label_offset(vd->vdev_psize, l, offset), size, buf, ZIO_CHECKSUM_LABEL, done, private, ZIO_PRIORITY_SYNC_READ, flags, B_TRUE)); } static void vdev_label_write(zio_t *zio, vdev_t *vd, int l, void *buf, uint64_t offset, uint64_t size, zio_done_func_t *done, void *private, int flags) { ASSERT(spa_config_held(zio->io_spa, SCL_ALL, RW_WRITER) == SCL_ALL || (spa_config_held(zio->io_spa, SCL_CONFIG | SCL_STATE, RW_READER) == (SCL_CONFIG | SCL_STATE) && dsl_pool_sync_context(spa_get_dsl(zio->io_spa)))); ASSERT(flags & ZIO_FLAG_CONFIG_WRITER); zio_nowait(zio_write_phys(zio, vd, vdev_label_offset(vd->vdev_psize, l, offset), size, buf, ZIO_CHECKSUM_LABEL, done, private, ZIO_PRIORITY_SYNC_WRITE, flags, B_TRUE)); } /* * Generate the nvlist representing this vdev's stats */ void vdev_config_generate_stats(vdev_t *vd, nvlist_t *nv) { nvlist_t *nvx; vdev_stat_t *vs; vdev_stat_ex_t *vsx; vs = kmem_alloc(sizeof (*vs), KM_SLEEP); vsx = kmem_alloc(sizeof (*vsx), KM_SLEEP); vdev_get_stats_ex(vd, vs, vsx); fnvlist_add_uint64_array(nv, ZPOOL_CONFIG_VDEV_STATS, (uint64_t *)vs, sizeof (*vs) / sizeof (uint64_t)); kmem_free(vs, sizeof (*vs)); /* * Add extended stats into a special extended stats nvlist. This keeps * all the extended stats nicely grouped together. The extended stats * nvlist is then added to the main nvlist. */ nvx = fnvlist_alloc(); /* ZIOs in flight to disk */ fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_ACTIVE_QUEUE, vsx->vsx_active_queue[ZIO_PRIORITY_SYNC_READ]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_ACTIVE_QUEUE, vsx->vsx_active_queue[ZIO_PRIORITY_SYNC_WRITE]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_ACTIVE_QUEUE, vsx->vsx_active_queue[ZIO_PRIORITY_ASYNC_READ]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_ACTIVE_QUEUE, vsx->vsx_active_queue[ZIO_PRIORITY_ASYNC_WRITE]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SCRUB_ACTIVE_QUEUE, vsx->vsx_active_queue[ZIO_PRIORITY_SCRUB]); /* ZIOs pending */ fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_PEND_QUEUE, vsx->vsx_pend_queue[ZIO_PRIORITY_SYNC_READ]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_PEND_QUEUE, vsx->vsx_pend_queue[ZIO_PRIORITY_SYNC_WRITE]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_PEND_QUEUE, vsx->vsx_pend_queue[ZIO_PRIORITY_ASYNC_READ]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_PEND_QUEUE, vsx->vsx_pend_queue[ZIO_PRIORITY_ASYNC_WRITE]); fnvlist_add_uint64(nvx, ZPOOL_CONFIG_VDEV_SCRUB_PEND_QUEUE, vsx->vsx_pend_queue[ZIO_PRIORITY_SCRUB]); /* Histograms */ fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_TOT_R_LAT_HISTO, vsx->vsx_total_histo[ZIO_TYPE_READ], ARRAY_SIZE(vsx->vsx_total_histo[ZIO_TYPE_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_TOT_W_LAT_HISTO, vsx->vsx_total_histo[ZIO_TYPE_WRITE], ARRAY_SIZE(vsx->vsx_total_histo[ZIO_TYPE_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_DISK_R_LAT_HISTO, vsx->vsx_disk_histo[ZIO_TYPE_READ], ARRAY_SIZE(vsx->vsx_disk_histo[ZIO_TYPE_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_DISK_W_LAT_HISTO, vsx->vsx_disk_histo[ZIO_TYPE_WRITE], ARRAY_SIZE(vsx->vsx_disk_histo[ZIO_TYPE_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_R_LAT_HISTO, vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_READ], ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_W_LAT_HISTO, vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_WRITE], ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_R_LAT_HISTO, vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_READ], ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_W_LAT_HISTO, vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_WRITE], ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_ASYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SCRUB_LAT_HISTO, vsx->vsx_queue_histo[ZIO_PRIORITY_SCRUB], ARRAY_SIZE(vsx->vsx_queue_histo[ZIO_PRIORITY_SCRUB])); /* Request sizes */ fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_IND_R_HISTO, vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_READ], ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_IND_W_HISTO, vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_WRITE], ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_IND_R_HISTO, vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_READ], ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_IND_W_HISTO, vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_WRITE], ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_ASYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_IND_SCRUB_HISTO, vsx->vsx_ind_histo[ZIO_PRIORITY_SCRUB], ARRAY_SIZE(vsx->vsx_ind_histo[ZIO_PRIORITY_SCRUB])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_AGG_R_HISTO, vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_READ], ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_SYNC_AGG_W_HISTO, vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_WRITE], ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_AGG_R_HISTO, vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_READ], ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_READ])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_ASYNC_AGG_W_HISTO, vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_WRITE], ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_ASYNC_WRITE])); fnvlist_add_uint64_array(nvx, ZPOOL_CONFIG_VDEV_AGG_SCRUB_HISTO, vsx->vsx_agg_histo[ZIO_PRIORITY_SCRUB], ARRAY_SIZE(vsx->vsx_agg_histo[ZIO_PRIORITY_SCRUB])); /* Add extended stats nvlist to main nvlist */ fnvlist_add_nvlist(nv, ZPOOL_CONFIG_VDEV_STATS_EX, nvx); fnvlist_free(nvx); kmem_free(vsx, sizeof (*vsx)); } /* * Generate the nvlist representing this vdev's config. */ nvlist_t * vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats, vdev_config_flag_t flags) { nvlist_t *nv = NULL; nv = fnvlist_alloc(); fnvlist_add_string(nv, ZPOOL_CONFIG_TYPE, vd->vdev_ops->vdev_op_type); if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE))) fnvlist_add_uint64(nv, ZPOOL_CONFIG_ID, vd->vdev_id); fnvlist_add_uint64(nv, ZPOOL_CONFIG_GUID, vd->vdev_guid); if (vd->vdev_path != NULL) fnvlist_add_string(nv, ZPOOL_CONFIG_PATH, vd->vdev_path); if (vd->vdev_devid != NULL) fnvlist_add_string(nv, ZPOOL_CONFIG_DEVID, vd->vdev_devid); if (vd->vdev_physpath != NULL) fnvlist_add_string(nv, ZPOOL_CONFIG_PHYS_PATH, vd->vdev_physpath); if (vd->vdev_fru != NULL) fnvlist_add_string(nv, ZPOOL_CONFIG_FRU, vd->vdev_fru); if (vd->vdev_nparity != 0) { ASSERT(strcmp(vd->vdev_ops->vdev_op_type, VDEV_TYPE_RAIDZ) == 0); /* * Make sure someone hasn't managed to sneak a fancy new vdev * into a crufty old storage pool. */ ASSERT(vd->vdev_nparity == 1 || (vd->vdev_nparity <= 2 && spa_version(spa) >= SPA_VERSION_RAIDZ2) || (vd->vdev_nparity <= 3 && spa_version(spa) >= SPA_VERSION_RAIDZ3)); /* * Note that we'll add the nparity tag even on storage pools * that only support a single parity device -- older software * will just ignore it. */ fnvlist_add_uint64(nv, ZPOOL_CONFIG_NPARITY, vd->vdev_nparity); } if (vd->vdev_wholedisk != -1ULL) fnvlist_add_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK, vd->vdev_wholedisk); if (vd->vdev_not_present) fnvlist_add_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT, 1); if (vd->vdev_isspare) fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_SPARE, 1); if (!(flags & (VDEV_CONFIG_SPARE | VDEV_CONFIG_L2CACHE)) && vd == vd->vdev_top) { fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY, vd->vdev_ms_array); fnvlist_add_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT, vd->vdev_ms_shift); fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASHIFT, vd->vdev_ashift); fnvlist_add_uint64(nv, ZPOOL_CONFIG_ASIZE, vd->vdev_asize); fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_LOG, vd->vdev_islog); if (vd->vdev_removing) fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVING, vd->vdev_removing); } if (vd->vdev_dtl_sm != NULL) { fnvlist_add_uint64(nv, ZPOOL_CONFIG_DTL, space_map_object(vd->vdev_dtl_sm)); } if (vd->vdev_crtxg) fnvlist_add_uint64(nv, ZPOOL_CONFIG_CREATE_TXG, vd->vdev_crtxg); if (flags & VDEV_CONFIG_MOS) { if (vd->vdev_leaf_zap != 0) { ASSERT(vd->vdev_ops->vdev_op_leaf); fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_LEAF_ZAP, vd->vdev_leaf_zap); } if (vd->vdev_top_zap != 0) { ASSERT(vd == vd->vdev_top); fnvlist_add_uint64(nv, ZPOOL_CONFIG_VDEV_TOP_ZAP, vd->vdev_top_zap); } } if (getstats) { pool_scan_stat_t ps; vdev_config_generate_stats(vd, nv); /* provide either current or previous scan information */ if (spa_scan_get_stats(spa, &ps) == 0) { fnvlist_add_uint64_array(nv, ZPOOL_CONFIG_SCAN_STATS, (uint64_t *)&ps, sizeof (pool_scan_stat_t) / sizeof (uint64_t)); } } if (!vd->vdev_ops->vdev_op_leaf) { nvlist_t **child; int c, idx; ASSERT(!vd->vdev_ishole); child = kmem_alloc(vd->vdev_children * sizeof (nvlist_t *), KM_SLEEP); for (c = 0, idx = 0; c < vd->vdev_children; c++) { vdev_t *cvd = vd->vdev_child[c]; /* * If we're generating an nvlist of removing * vdevs then skip over any device which is * not being removed. */ if ((flags & VDEV_CONFIG_REMOVING) && !cvd->vdev_removing) continue; child[idx++] = vdev_config_generate(spa, cvd, getstats, flags); } if (idx) { fnvlist_add_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN, child, idx); } for (c = 0; c < idx; c++) nvlist_free(child[c]); kmem_free(child, vd->vdev_children * sizeof (nvlist_t *)); } else { const char *aux = NULL; if (vd->vdev_offline && !vd->vdev_tmpoffline) fnvlist_add_uint64(nv, ZPOOL_CONFIG_OFFLINE, B_TRUE); if (vd->vdev_resilver_txg != 0) fnvlist_add_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG, vd->vdev_resilver_txg); if (vd->vdev_faulted) fnvlist_add_uint64(nv, ZPOOL_CONFIG_FAULTED, B_TRUE); if (vd->vdev_degraded) fnvlist_add_uint64(nv, ZPOOL_CONFIG_DEGRADED, B_TRUE); if (vd->vdev_removed) fnvlist_add_uint64(nv, ZPOOL_CONFIG_REMOVED, B_TRUE); if (vd->vdev_unspare) fnvlist_add_uint64(nv, ZPOOL_CONFIG_UNSPARE, B_TRUE); if (vd->vdev_ishole) fnvlist_add_uint64(nv, ZPOOL_CONFIG_IS_HOLE, B_TRUE); switch (vd->vdev_stat.vs_aux) { case VDEV_AUX_ERR_EXCEEDED: aux = "err_exceeded"; break; case VDEV_AUX_EXTERNAL: aux = "external"; break; } if (aux != NULL) fnvlist_add_string(nv, ZPOOL_CONFIG_AUX_STATE, aux); if (vd->vdev_splitting && vd->vdev_orig_guid != 0LL) { fnvlist_add_uint64(nv, ZPOOL_CONFIG_ORIG_GUID, vd->vdev_orig_guid); } } return (nv); } /* * Generate a view of the top-level vdevs. If we currently have holes * in the namespace, then generate an array which contains a list of holey * vdevs. Additionally, add the number of top-level children that currently * exist. */ void vdev_top_config_generate(spa_t *spa, nvlist_t *config) { vdev_t *rvd = spa->spa_root_vdev; uint64_t *array; uint_t c, idx; array = kmem_alloc(rvd->vdev_children * sizeof (uint64_t), KM_SLEEP); for (c = 0, idx = 0; c < rvd->vdev_children; c++) { vdev_t *tvd = rvd->vdev_child[c]; if (tvd->vdev_ishole) array[idx++] = c; } if (idx) { VERIFY(nvlist_add_uint64_array(config, ZPOOL_CONFIG_HOLE_ARRAY, array, idx) == 0); } VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN, rvd->vdev_children) == 0); kmem_free(array, rvd->vdev_children * sizeof (uint64_t)); } /* * Returns the configuration from the label of the given vdev. For vdevs * which don't have a txg value stored on their label (i.e. spares/cache) * or have not been completely initialized (txg = 0) just return * the configuration from the first valid label we find. Otherwise, * find the most up-to-date label that does not exceed the specified * 'txg' value. */ nvlist_t * vdev_label_read_config(vdev_t *vd, uint64_t txg) { spa_t *spa = vd->vdev_spa; nvlist_t *config = NULL; vdev_phys_t *vp; zio_t *zio; uint64_t best_txg = 0; int error = 0; int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE; int l; ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL); if (!vdev_readable(vd)) return (NULL); vp = zio_buf_alloc(sizeof (vdev_phys_t)); retry: for (l = 0; l < VDEV_LABELS; l++) { nvlist_t *label = NULL; zio = zio_root(spa, NULL, NULL, flags); vdev_label_read(zio, vd, l, vp, offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t), NULL, NULL, flags); if (zio_wait(zio) == 0 && nvlist_unpack(vp->vp_nvlist, sizeof (vp->vp_nvlist), &label, 0) == 0) { uint64_t label_txg = 0; /* * Auxiliary vdevs won't have txg values in their * labels and newly added vdevs may not have been * completely initialized so just return the * configuration from the first valid label we * encounter. */ error = nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG, &label_txg); if ((error || label_txg == 0) && !config) { config = label; break; } else if (label_txg <= txg && label_txg > best_txg) { best_txg = label_txg; nvlist_free(config); config = fnvlist_dup(label); } } if (label != NULL) { nvlist_free(label); label = NULL; } } if (config == NULL && !(flags & ZIO_FLAG_TRYHARD)) { flags |= ZIO_FLAG_TRYHARD; goto retry; } zio_buf_free(vp, sizeof (vdev_phys_t)); return (config); } /* * Determine if a device is in use. The 'spare_guid' parameter will be filled * in with the device guid if this spare is active elsewhere on the system. */ static boolean_t vdev_inuse(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason, uint64_t *spare_guid, uint64_t *l2cache_guid) { spa_t *spa = vd->vdev_spa; uint64_t state, pool_guid, device_guid, txg, spare_pool; uint64_t vdtxg = 0; nvlist_t *label; if (spare_guid) *spare_guid = 0ULL; if (l2cache_guid) *l2cache_guid = 0ULL; /* * Read the label, if any, and perform some basic sanity checks. */ if ((label = vdev_label_read_config(vd, -1ULL)) == NULL) return (B_FALSE); (void) nvlist_lookup_uint64(label, ZPOOL_CONFIG_CREATE_TXG, &vdtxg); if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, &state) != 0 || nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &device_guid) != 0) { nvlist_free(label); return (B_FALSE); } if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE && (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID, &pool_guid) != 0 || nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_TXG, &txg) != 0)) { nvlist_free(label); return (B_FALSE); } nvlist_free(label); /* * Check to see if this device indeed belongs to the pool it claims to * be a part of. The only way this is allowed is if the device is a hot * spare (which we check for later on). */ if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE && !spa_guid_exists(pool_guid, device_guid) && !spa_spare_exists(device_guid, NULL, NULL) && !spa_l2cache_exists(device_guid, NULL)) return (B_FALSE); /* * If the transaction group is zero, then this an initialized (but * unused) label. This is only an error if the create transaction * on-disk is the same as the one we're using now, in which case the * user has attempted to add the same vdev multiple times in the same * transaction. */ if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE && txg == 0 && vdtxg == crtxg) return (B_TRUE); /* * Check to see if this is a spare device. We do an explicit check for * spa_has_spare() here because it may be on our pending list of spares * to add. We also check if it is an l2cache device. */ if (spa_spare_exists(device_guid, &spare_pool, NULL) || spa_has_spare(spa, device_guid)) { if (spare_guid) *spare_guid = device_guid; switch (reason) { case VDEV_LABEL_CREATE: case VDEV_LABEL_L2CACHE: return (B_TRUE); case VDEV_LABEL_REPLACE: return (!spa_has_spare(spa, device_guid) || spare_pool != 0ULL); case VDEV_LABEL_SPARE: return (spa_has_spare(spa, device_guid)); default: break; } } /* * Check to see if this is an l2cache device. */ if (spa_l2cache_exists(device_guid, NULL)) return (B_TRUE); /* * We can't rely on a pool's state if it's been imported * read-only. Instead we look to see if the pools is marked * read-only in the namespace and set the state to active. */ if (state != POOL_STATE_SPARE && state != POOL_STATE_L2CACHE && (spa = spa_by_guid(pool_guid, device_guid)) != NULL && spa_mode(spa) == FREAD) state = POOL_STATE_ACTIVE; /* * If the device is marked ACTIVE, then this device is in use by another * pool on the system. */ return (state == POOL_STATE_ACTIVE); } /* * Initialize a vdev label. We check to make sure each leaf device is not in * use, and writable. We put down an initial label which we will later * overwrite with a complete label. Note that it's important to do this * sequentially, not in parallel, so that we catch cases of multiple use of the * same leaf vdev in the vdev we're creating -- e.g. mirroring a disk with * itself. */ int vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason) { spa_t *spa = vd->vdev_spa; nvlist_t *label; vdev_phys_t *vp; char *pad2; uberblock_t *ub; zio_t *zio; char *buf; size_t buflen; int error; uint64_t spare_guid = 0, l2cache_guid = 0; int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL; int c, l; vdev_t *pvd; ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL); for (c = 0; c < vd->vdev_children; c++) if ((error = vdev_label_init(vd->vdev_child[c], crtxg, reason)) != 0) return (error); /* Track the creation time for this vdev */ vd->vdev_crtxg = crtxg; if (!vd->vdev_ops->vdev_op_leaf || !spa_writeable(spa)) return (0); /* * Dead vdevs cannot be initialized. */ if (vdev_is_dead(vd)) return (SET_ERROR(EIO)); /* * Determine if the vdev is in use. */ if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPLIT && vdev_inuse(vd, crtxg, reason, &spare_guid, &l2cache_guid)) return (SET_ERROR(EBUSY)); /* * If this is a request to add or replace a spare or l2cache device * that is in use elsewhere on the system, then we must update the * guid (which was initialized to a random value) to reflect the * actual GUID (which is shared between multiple pools). */ if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_L2CACHE && spare_guid != 0ULL) { uint64_t guid_delta = spare_guid - vd->vdev_guid; vd->vdev_guid += guid_delta; for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent) pvd->vdev_guid_sum += guid_delta; /* * If this is a replacement, then we want to fallthrough to the * rest of the code. If we're adding a spare, then it's already * labeled appropriately and we can just return. */ if (reason == VDEV_LABEL_SPARE) return (0); ASSERT(reason == VDEV_LABEL_REPLACE || reason == VDEV_LABEL_SPLIT); } if (reason != VDEV_LABEL_REMOVE && reason != VDEV_LABEL_SPARE && l2cache_guid != 0ULL) { uint64_t guid_delta = l2cache_guid - vd->vdev_guid; vd->vdev_guid += guid_delta; for (pvd = vd; pvd != NULL; pvd = pvd->vdev_parent) pvd->vdev_guid_sum += guid_delta; /* * If this is a replacement, then we want to fallthrough to the * rest of the code. If we're adding an l2cache, then it's * already labeled appropriately and we can just return. */ if (reason == VDEV_LABEL_L2CACHE) return (0); ASSERT(reason == VDEV_LABEL_REPLACE); } /* * Initialize its label. */ vp = zio_buf_alloc(sizeof (vdev_phys_t)); bzero(vp, sizeof (vdev_phys_t)); /* * Generate a label describing the pool and our top-level vdev. * We mark it as being from txg 0 to indicate that it's not * really part of an active pool just yet. The labels will * be written again with a meaningful txg by spa_sync(). */ if (reason == VDEV_LABEL_SPARE || (reason == VDEV_LABEL_REMOVE && vd->vdev_isspare)) { /* * For inactive hot spares, we generate a special label that * identifies as a mutually shared hot spare. We write the * label if we are adding a hot spare, or if we are removing an * active hot spare (in which case we want to revert the * labels). */ VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION, spa_version(spa)) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE, POOL_STATE_SPARE) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0); } else if (reason == VDEV_LABEL_L2CACHE || (reason == VDEV_LABEL_REMOVE && vd->vdev_isl2cache)) { /* * For level 2 ARC devices, add a special label. */ VERIFY(nvlist_alloc(&label, NV_UNIQUE_NAME, KM_SLEEP) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_VERSION, spa_version(spa)) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_POOL_STATE, POOL_STATE_L2CACHE) == 0); VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID, vd->vdev_guid) == 0); } else { uint64_t txg = 0ULL; if (reason == VDEV_LABEL_SPLIT) txg = spa->spa_uberblock.ub_txg; label = spa_config_generate(spa, vd, txg, B_FALSE); /* * Add our creation time. This allows us to detect multiple * vdev uses as described above, and automatically expires if we * fail. */ VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_CREATE_TXG, crtxg) == 0); } buf = vp->vp_nvlist; buflen = sizeof (vp->vp_nvlist); error = nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP); if (error != 0) { nvlist_free(label); zio_buf_free(vp, sizeof (vdev_phys_t)); /* EFAULT means nvlist_pack ran out of room */ return (error == EFAULT ? ENAMETOOLONG : EINVAL); } /* * Initialize uberblock template. */ ub = zio_buf_alloc(VDEV_UBERBLOCK_RING); bzero(ub, VDEV_UBERBLOCK_RING); *ub = spa->spa_uberblock; ub->ub_txg = 0; /* Initialize the 2nd padding area. */ pad2 = zio_buf_alloc(VDEV_PAD_SIZE); bzero(pad2, VDEV_PAD_SIZE); /* * Write everything in parallel. */ retry: zio = zio_root(spa, NULL, NULL, flags); for (l = 0; l < VDEV_LABELS; l++) { vdev_label_write(zio, vd, l, vp, offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t), NULL, NULL, flags); /* * Skip the 1st padding area. * Zero out the 2nd padding area where it might have * left over data from previous filesystem format. */ vdev_label_write(zio, vd, l, pad2, offsetof(vdev_label_t, vl_pad2), VDEV_PAD_SIZE, NULL, NULL, flags); vdev_label_write(zio, vd, l, ub, offsetof(vdev_label_t, vl_uberblock), VDEV_UBERBLOCK_RING, NULL, NULL, flags); } error = zio_wait(zio); if (error != 0 && !(flags & ZIO_FLAG_TRYHARD)) { flags |= ZIO_FLAG_TRYHARD; goto retry; } nvlist_free(label); zio_buf_free(pad2, VDEV_PAD_SIZE); zio_buf_free(ub, VDEV_UBERBLOCK_RING); zio_buf_free(vp, sizeof (vdev_phys_t)); /* * If this vdev hasn't been previously identified as a spare, then we * mark it as such only if a) we are labeling it as a spare, or b) it * exists as a spare elsewhere in the system. Do the same for * level 2 ARC devices. */ if (error == 0 && !vd->vdev_isspare && (reason == VDEV_LABEL_SPARE || spa_spare_exists(vd->vdev_guid, NULL, NULL))) spa_spare_add(vd); if (error == 0 && !vd->vdev_isl2cache && (reason == VDEV_LABEL_L2CACHE || spa_l2cache_exists(vd->vdev_guid, NULL))) spa_l2cache_add(vd); return (error); } /* * ========================================================================== * uberblock load/sync * ========================================================================== */ /* * Consider the following situation: txg is safely synced to disk. We've * written the first uberblock for txg + 1, and then we lose power. When we * come back up, we fail to see the uberblock for txg + 1 because, say, * it was on a mirrored device and the replica to which we wrote txg + 1 * is now offline. If we then make some changes and sync txg + 1, and then * the missing replica comes back, then for a few seconds we'll have two * conflicting uberblocks on disk with the same txg. The solution is simple: * among uberblocks with equal txg, choose the one with the latest timestamp. */ static int vdev_uberblock_compare(const uberblock_t *ub1, const uberblock_t *ub2) { int cmp = AVL_CMP(ub1->ub_txg, ub2->ub_txg); if (likely(cmp)) return (cmp); return (AVL_CMP(ub1->ub_timestamp, ub2->ub_timestamp)); } struct ubl_cbdata { uberblock_t *ubl_ubbest; /* Best uberblock */ vdev_t *ubl_vd; /* vdev associated with the above */ }; static void vdev_uberblock_load_done(zio_t *zio) { vdev_t *vd = zio->io_vd; spa_t *spa = zio->io_spa; zio_t *rio = zio->io_private; uberblock_t *ub = zio->io_data; struct ubl_cbdata *cbp = rio->io_private; ASSERT3U(zio->io_size, ==, VDEV_UBERBLOCK_SIZE(vd)); if (zio->io_error == 0 && uberblock_verify(ub) == 0) { mutex_enter(&rio->io_lock); if (ub->ub_txg <= spa->spa_load_max_txg && vdev_uberblock_compare(ub, cbp->ubl_ubbest) > 0) { /* * Keep track of the vdev in which this uberblock * was found. We will use this information later * to obtain the config nvlist associated with * this uberblock. */ *cbp->ubl_ubbest = *ub; cbp->ubl_vd = vd; } mutex_exit(&rio->io_lock); } zio_buf_free(zio->io_data, zio->io_size); } static void vdev_uberblock_load_impl(zio_t *zio, vdev_t *vd, int flags, struct ubl_cbdata *cbp) { int c, l, n; for (c = 0; c < vd->vdev_children; c++) vdev_uberblock_load_impl(zio, vd->vdev_child[c], flags, cbp); if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) { for (l = 0; l < VDEV_LABELS; l++) { for (n = 0; n < VDEV_UBERBLOCK_COUNT(vd); n++) { vdev_label_read(zio, vd, l, zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)), VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd), vdev_uberblock_load_done, zio, flags); } } } } /* * Reads the 'best' uberblock from disk along with its associated * configuration. First, we read the uberblock array of each label of each * vdev, keeping track of the uberblock with the highest txg in each array. * Then, we read the configuration from the same vdev as the best uberblock. */ void vdev_uberblock_load(vdev_t *rvd, uberblock_t *ub, nvlist_t **config) { zio_t *zio; spa_t *spa = rvd->vdev_spa; struct ubl_cbdata cb; int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_TRYHARD; ASSERT(ub); ASSERT(config); bzero(ub, sizeof (uberblock_t)); *config = NULL; cb.ubl_ubbest = ub; cb.ubl_vd = NULL; spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER); zio = zio_root(spa, NULL, &cb, flags); vdev_uberblock_load_impl(zio, rvd, flags, &cb); (void) zio_wait(zio); /* * It's possible that the best uberblock was discovered on a label * that has a configuration which was written in a future txg. * Search all labels on this vdev to find the configuration that * matches the txg for our uberblock. */ if (cb.ubl_vd != NULL) *config = vdev_label_read_config(cb.ubl_vd, ub->ub_txg); spa_config_exit(spa, SCL_ALL, FTAG); } /* * On success, increment root zio's count of good writes. * We only get credit for writes to known-visible vdevs; see spa_vdev_add(). */ static void vdev_uberblock_sync_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (zio->io_error == 0 && zio->io_vd->vdev_top->vdev_ms_array != 0) atomic_inc_64(good_writes); } /* * Write the uberblock to all labels of all leaves of the specified vdev. */ static void vdev_uberblock_sync(zio_t *zio, uberblock_t *ub, vdev_t *vd, int flags) { uberblock_t *ubbuf; int c, l, n; for (c = 0; c < vd->vdev_children; c++) vdev_uberblock_sync(zio, ub, vd->vdev_child[c], flags); if (!vd->vdev_ops->vdev_op_leaf) return; if (!vdev_writeable(vd)) return; n = ub->ub_txg & (VDEV_UBERBLOCK_COUNT(vd) - 1); ubbuf = zio_buf_alloc(VDEV_UBERBLOCK_SIZE(vd)); bzero(ubbuf, VDEV_UBERBLOCK_SIZE(vd)); *ubbuf = *ub; for (l = 0; l < VDEV_LABELS; l++) vdev_label_write(zio, vd, l, ubbuf, VDEV_UBERBLOCK_OFFSET(vd, n), VDEV_UBERBLOCK_SIZE(vd), vdev_uberblock_sync_done, zio->io_private, flags | ZIO_FLAG_DONT_PROPAGATE); zio_buf_free(ubbuf, VDEV_UBERBLOCK_SIZE(vd)); } /* Sync the uberblocks to all vdevs in svd[] */ int vdev_uberblock_sync_list(vdev_t **svd, int svdcount, uberblock_t *ub, int flags) { spa_t *spa = svd[0]->vdev_spa; zio_t *zio; uint64_t good_writes = 0; int v; zio = zio_root(spa, NULL, &good_writes, flags); for (v = 0; v < svdcount; v++) vdev_uberblock_sync(zio, ub, svd[v], flags); (void) zio_wait(zio); /* * Flush the uberblocks to disk. This ensures that the odd labels * are no longer needed (because the new uberblocks and the even * labels are safely on disk), so it is safe to overwrite them. */ zio = zio_root(spa, NULL, NULL, flags); for (v = 0; v < svdcount; v++) zio_flush(zio, svd[v]); (void) zio_wait(zio); return (good_writes >= 1 ? 0 : EIO); } /* * On success, increment the count of good writes for our top-level vdev. */ static void vdev_label_sync_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (zio->io_error == 0) atomic_inc_64(good_writes); } /* * If there weren't enough good writes, indicate failure to the parent. */ static void vdev_label_sync_top_done(zio_t *zio) { uint64_t *good_writes = zio->io_private; if (*good_writes == 0) zio->io_error = SET_ERROR(EIO); kmem_free(good_writes, sizeof (uint64_t)); } /* * We ignore errors for log and cache devices, simply free the private data. */ static void vdev_label_sync_ignore_done(zio_t *zio) { kmem_free(zio->io_private, sizeof (uint64_t)); } /* * Write all even or odd labels to all leaves of the specified vdev. */ static void vdev_label_sync(zio_t *zio, vdev_t *vd, int l, uint64_t txg, int flags) { nvlist_t *label; vdev_phys_t *vp; char *buf; size_t buflen; int c; for (c = 0; c < vd->vdev_children; c++) vdev_label_sync(zio, vd->vdev_child[c], l, txg, flags); if (!vd->vdev_ops->vdev_op_leaf) return; if (!vdev_writeable(vd)) return; /* * Generate a label describing the top-level config to which we belong. */ label = spa_config_generate(vd->vdev_spa, vd, txg, B_FALSE); vp = zio_buf_alloc(sizeof (vdev_phys_t)); bzero(vp, sizeof (vdev_phys_t)); buf = vp->vp_nvlist; buflen = sizeof (vp->vp_nvlist); if (!nvlist_pack(label, &buf, &buflen, NV_ENCODE_XDR, KM_SLEEP)) { for (; l < VDEV_LABELS; l += 2) { vdev_label_write(zio, vd, l, vp, offsetof(vdev_label_t, vl_vdev_phys), sizeof (vdev_phys_t), vdev_label_sync_done, zio->io_private, flags | ZIO_FLAG_DONT_PROPAGATE); } } zio_buf_free(vp, sizeof (vdev_phys_t)); nvlist_free(label); } int vdev_label_sync_list(spa_t *spa, int l, uint64_t txg, int flags) { list_t *dl = &spa->spa_config_dirty_list; vdev_t *vd; zio_t *zio; int error; /* * Write the new labels to disk. */ zio = zio_root(spa, NULL, NULL, flags); for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) { uint64_t *good_writes; zio_t *vio; ASSERT(!vd->vdev_ishole); good_writes = kmem_zalloc(sizeof (uint64_t), KM_SLEEP); vio = zio_null(zio, spa, NULL, (vd->vdev_islog || vd->vdev_aux != NULL) ? vdev_label_sync_ignore_done : vdev_label_sync_top_done, good_writes, flags); vdev_label_sync(vio, vd, l, txg, flags); zio_nowait(vio); } error = zio_wait(zio); /* * Flush the new labels to disk. */ zio = zio_root(spa, NULL, NULL, flags); for (vd = list_head(dl); vd != NULL; vd = list_next(dl, vd)) zio_flush(zio, vd); (void) zio_wait(zio); return (error); } /* * Sync the uberblock and any changes to the vdev configuration. * * The order of operations is carefully crafted to ensure that * if the system panics or loses power at any time, the state on disk * is still transactionally consistent. The in-line comments below * describe the failure semantics at each stage. * * Moreover, vdev_config_sync() is designed to be idempotent: if it fails * at any time, you can just call it again, and it will resume its work. */ int vdev_config_sync(vdev_t **svd, int svdcount, uint64_t txg) { spa_t *spa = svd[0]->vdev_spa; uberblock_t *ub = &spa->spa_uberblock; vdev_t *vd; zio_t *zio; int error = 0; int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL; retry: /* * Normally, we don't want to try too hard to write every label and * uberblock. If there is a flaky disk, we don't want the rest of the * sync process to block while we retry. But if we can't write a * single label out, we should retry with ZIO_FLAG_TRYHARD before * bailing out and declaring the pool faulted. */ if (error != 0) { if ((flags & ZIO_FLAG_TRYHARD) != 0) return (error); flags |= ZIO_FLAG_TRYHARD; } ASSERT(ub->ub_txg <= txg); /* * If this isn't a resync due to I/O errors, * and nothing changed in this transaction group, * and the vdev configuration hasn't changed, * then there's nothing to do. */ if (ub->ub_txg < txg && uberblock_update(ub, spa->spa_root_vdev, txg) == B_FALSE && list_is_empty(&spa->spa_config_dirty_list)) return (0); if (txg > spa_freeze_txg(spa)) return (0); ASSERT(txg <= spa->spa_final_txg); /* * Flush the write cache of every disk that's been written to * in this transaction group. This ensures that all blocks * written in this txg will be committed to stable storage * before any uberblock that references them. */ zio = zio_root(spa, NULL, NULL, flags); for (vd = txg_list_head(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)); vd; vd = txg_list_next(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg))) zio_flush(zio, vd); (void) zio_wait(zio); /* * Sync out the even labels (L0, L2) for every dirty vdev. If the * system dies in the middle of this process, that's OK: all of the * even labels that made it to disk will be newer than any uberblock, * and will therefore be considered invalid. The odd labels (L1, L3), * which have not yet been touched, will still be valid. We flush * the new labels to disk to ensure that all even-label updates * are committed to stable storage before the uberblock update. */ if ((error = vdev_label_sync_list(spa, 0, txg, flags)) != 0) goto retry; /* * Sync the uberblocks to all vdevs in svd[]. * If the system dies in the middle of this step, there are two cases * to consider, and the on-disk state is consistent either way: * * (1) If none of the new uberblocks made it to disk, then the * previous uberblock will be the newest, and the odd labels * (which had not yet been touched) will be valid with respect * to that uberblock. * * (2) If one or more new uberblocks made it to disk, then they * will be the newest, and the even labels (which had all * been successfully committed) will be valid with respect * to the new uberblocks. */ if ((error = vdev_uberblock_sync_list(svd, svdcount, ub, flags)) != 0) goto retry; /* * Sync out odd labels for every dirty vdev. If the system dies * in the middle of this process, the even labels and the new * uberblocks will suffice to open the pool. The next time * the pool is opened, the first thing we'll do -- before any * user data is modified -- is mark every vdev dirty so that * all labels will be brought up to date. We flush the new labels * to disk to ensure that all odd-label updates are committed to * stable storage before the next transaction group begins. */ if ((error = vdev_label_sync_list(spa, 1, txg, flags)) != 0) goto retry; return (0); }