fs/zfs/vdev.c

/*
 * 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) 2011, 2018 by Delphix. All rights reserved.
 * Copyright 2017 Nexenta Systems, Inc.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2016 Toomas Soome <tsoome@me.com>
 * Copyright 2019 Joyent, Inc.
 * Copyright (c) 2017, Intel Corporation.
 * Copyright (c) 2019, Datto Inc. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/fm/fs/zfs.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/bpobj.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/dsl_dir.h>
#include <sys/vdev_impl.h>
#include <sys/uberblock_impl.h>
#include <sys/metaslab.h>
#include <sys/metaslab_impl.h>
#include <sys/space_map.h>
#include <sys/space_reftree.h>
#include <sys/zio.h>
#include <sys/zap.h>
#include <sys/fs/zfs.h>
#include <sys/arc.h>
#include <sys/zil.h>
#include <sys/dsl_scan.h>
#include <sys/abd.h>
#include <sys/vdev_initialize.h>
#include <sys/vdev_trim.h>

/*
 * Virtual device management.
 */

static vdev_ops_t *vdev_ops_table[] = {
	&vdev_root_ops,
	&vdev_raidz_ops,
	&vdev_mirror_ops,
	&vdev_replacing_ops,
	&vdev_spare_ops,
	&vdev_disk_ops,
	&vdev_file_ops,
	&vdev_missing_ops,
	&vdev_hole_ops,
	&vdev_indirect_ops,
	NULL
};

/* maximum scrub/resilver I/O queue per leaf vdev */
int zfs_scrub_limit = 10;

/* default target for number of metaslabs per top-level vdev */
int zfs_vdev_default_ms_count = 200;

/* minimum number of metaslabs per top-level vdev */
int zfs_vdev_min_ms_count = 16;

/* practical upper limit of total metaslabs per top-level vdev */
int zfs_vdev_ms_count_limit = 1ULL << 17;

/* lower limit for metaslab size (512M) */
int zfs_vdev_default_ms_shift = 29;

/* upper limit for metaslab size (16G) */
int zfs_vdev_max_ms_shift = 34;

boolean_t vdev_validate_skip = B_FALSE;

/*
 * Since the DTL space map of a vdev is not expected to have a lot of
 * entries, we default its block size to 4K.
 */
int zfs_vdev_dtl_sm_blksz = (1 << 12);

/*
 * Ignore errors during scrub/resilver.  Allows to work around resilver
 * upon import when there are pool errors.
 */
int zfs_scan_ignore_errors = 0;

/*
 * vdev-wide space maps that have lots of entries written to them at
 * the end of each transaction can benefit from a higher I/O bandwidth
 * (e.g. vdev_obsolete_sm), thus we default their block size to 128K.
 */
int zfs_vdev_standard_sm_blksz = (1 << 17);

int zfs_ashift_min;

/*PRINTFLIKE2*/
void
vdev_dbgmsg(vdev_t *vd, const char *fmt, ...)
{
	va_list adx;
	char buf[256];

	va_start(adx, fmt);
	(void) vsnprintf(buf, sizeof (buf), fmt, adx);
	va_end(adx);

	if (vd->vdev_path != NULL) {
		zfs_dbgmsg("%s vdev '%s': %s", vd->vdev_ops->vdev_op_type,
		    vd->vdev_path, buf);
	} else {
		zfs_dbgmsg("%s-%llu vdev (guid %llu): %s",
		    vd->vdev_ops->vdev_op_type,
		    (u_longlong_t)vd->vdev_id,
		    (u_longlong_t)vd->vdev_guid, buf);
	}
}

void
vdev_dbgmsg_print_tree(vdev_t *vd, int indent)
{
	char state[20];

	if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops) {
		zfs_dbgmsg("%*svdev %u: %s", indent, "", vd->vdev_id,
		    vd->vdev_ops->vdev_op_type);
		return;
	}

	switch (vd->vdev_state) {
	case VDEV_STATE_UNKNOWN:
		(void) snprintf(state, sizeof (state), "unknown");
		break;
	case VDEV_STATE_CLOSED:
		(void) snprintf(state, sizeof (state), "closed");
		break;
	case VDEV_STATE_OFFLINE:
		(void) snprintf(state, sizeof (state), "offline");
		break;
	case VDEV_STATE_REMOVED:
		(void) snprintf(state, sizeof (state), "removed");
		break;
	case VDEV_STATE_CANT_OPEN:
		(void) snprintf(state, sizeof (state), "can't open");
		break;
	case VDEV_STATE_FAULTED:
		(void) snprintf(state, sizeof (state), "faulted");
		break;
	case VDEV_STATE_DEGRADED:
		(void) snprintf(state, sizeof (state), "degraded");
		break;
	case VDEV_STATE_HEALTHY:
		(void) snprintf(state, sizeof (state), "healthy");
		break;
	default:
		(void) snprintf(state, sizeof (state), "<state %u>",
		    (uint_t)vd->vdev_state);
	}

	zfs_dbgmsg("%*svdev %u: %s%s, guid: %llu, path: %s, %s", indent,
	    "", (int)vd->vdev_id, vd->vdev_ops->vdev_op_type,
	    vd->vdev_islog ? " (log)" : "",
	    (u_longlong_t)vd->vdev_guid,
	    vd->vdev_path ? vd->vdev_path : "N/A", state);

	for (uint64_t i = 0; i < vd->vdev_children; i++)
		vdev_dbgmsg_print_tree(vd->vdev_child[i], indent + 2);
}

/*
 * Given a vdev type, return the appropriate ops vector.
 */
static vdev_ops_t *
vdev_getops(const char *type)
{
	vdev_ops_t *ops, **opspp;

	for (opspp = vdev_ops_table; (ops = *opspp) != NULL; opspp++)
		if (strcmp(ops->vdev_op_type, type) == 0)
			break;

	return (ops);
}

/*
 * Derive the enumerated alloction bias from string input.
 * String origin is either the per-vdev zap or zpool(1M).
 */
static vdev_alloc_bias_t
vdev_derive_alloc_bias(const char *bias)
{
	vdev_alloc_bias_t alloc_bias = VDEV_BIAS_NONE;

	if (strcmp(bias, VDEV_ALLOC_BIAS_LOG) == 0)
		alloc_bias = VDEV_BIAS_LOG;
	else if (strcmp(bias, VDEV_ALLOC_BIAS_SPECIAL) == 0)
		alloc_bias = VDEV_BIAS_SPECIAL;
	else if (strcmp(bias, VDEV_ALLOC_BIAS_DEDUP) == 0)
		alloc_bias = VDEV_BIAS_DEDUP;

	return (alloc_bias);
}

/* ARGSUSED */
void
vdev_default_xlate(vdev_t *vd, const range_seg64_t *in, range_seg64_t *res)
{
	res->rs_start = in->rs_start;
	res->rs_end = in->rs_end;
}

/*
 * Default asize function: return the MAX of psize with the asize of
 * all children.  This is what's used by anything other than RAID-Z.
 */
uint64_t
vdev_default_asize(vdev_t *vd, uint64_t psize)
{
	uint64_t asize = P2ROUNDUP(psize, 1ULL << vd->vdev_top->vdev_ashift);
	uint64_t csize;

	for (int c = 0; c < vd->vdev_children; c++) {
		csize = vdev_psize_to_asize(vd->vdev_child[c], psize);
		asize = MAX(asize, csize);
	}

	return (asize);
}

/*
 * Get the minimum allocatable size. We define the allocatable size as
 * the vdev's asize rounded to the nearest metaslab. This allows us to
 * replace or attach devices which don't have the same physical size but
 * can still satisfy the same number of allocations.
 */
uint64_t
vdev_get_min_asize(vdev_t *vd)
{
	vdev_t *pvd = vd->vdev_parent;

	/*
	 * If our parent is NULL (inactive spare or cache) or is the root,
	 * just return our own asize.
	 */
	if (pvd == NULL)
		return (vd->vdev_asize);

	/*
	 * The top-level vdev just returns the allocatable size rounded
	 * to the nearest metaslab.
	 */
	if (vd == vd->vdev_top)
		return (P2ALIGN(vd->vdev_asize, 1ULL << vd->vdev_ms_shift));

	/*
	 * The allocatable space for a raidz vdev is N * sizeof(smallest child),
	 * so each child must provide at least 1/Nth of its asize.
	 */
	if (pvd->vdev_ops == &vdev_raidz_ops)
		return ((pvd->vdev_min_asize + pvd->vdev_children - 1) /
		    pvd->vdev_children);

	return (pvd->vdev_min_asize);
}

void
vdev_set_min_asize(vdev_t *vd)
{
	vd->vdev_min_asize = vdev_get_min_asize(vd);

	for (int c = 0; c < vd->vdev_children; c++)
		vdev_set_min_asize(vd->vdev_child[c]);
}

vdev_t *
vdev_lookup_top(spa_t *spa, uint64_t vdev)
{
	vdev_t *rvd = spa->spa_root_vdev;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);

	if (vdev < rvd->vdev_children) {
		ASSERT(rvd->vdev_child[vdev] != NULL);
		return (rvd->vdev_child[vdev]);
	}

	return (NULL);
}

vdev_t *
vdev_lookup_by_guid(vdev_t *vd, uint64_t guid)
{
	vdev_t *mvd;

	if (vd->vdev_guid == guid)
		return (vd);

	for (int c = 0; c < vd->vdev_children; c++)
		if ((mvd = vdev_lookup_by_guid(vd->vdev_child[c], guid)) !=
		    NULL)
			return (mvd);

	return (NULL);
}

static int
vdev_count_leaves_impl(vdev_t *vd)
{
	int n = 0;

	if (vd->vdev_ops->vdev_op_leaf)
		return (1);

	for (int c = 0; c < vd->vdev_children; c++)
		n += vdev_count_leaves_impl(vd->vdev_child[c]);

	return (n);
}

int
vdev_count_leaves(spa_t *spa)
{
	return (vdev_count_leaves_impl(spa->spa_root_vdev));
}

void
vdev_add_child(vdev_t *pvd, vdev_t *cvd)
{
	size_t oldsize, newsize;
	uint64_t id = cvd->vdev_id;
	vdev_t **newchild;
	spa_t *spa = cvd->vdev_spa;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
	ASSERT(cvd->vdev_parent == NULL);

	cvd->vdev_parent = pvd;

	if (pvd == NULL)
		return;

	ASSERT(id >= pvd->vdev_children || pvd->vdev_child[id] == NULL);

	oldsize = pvd->vdev_children * sizeof (vdev_t *);
	pvd->vdev_children = MAX(pvd->vdev_children, id + 1);
	newsize = pvd->vdev_children * sizeof (vdev_t *);

	newchild = kmem_zalloc(newsize, KM_SLEEP);
	if (pvd->vdev_child != NULL) {
		bcopy(pvd->vdev_child, newchild, oldsize);
		kmem_free(pvd->vdev_child, oldsize);
	}

	pvd->vdev_child = newchild;
	pvd->vdev_child[id] = cvd;

	cvd->vdev_top = (pvd->vdev_top ? pvd->vdev_top: cvd);
	ASSERT(cvd->vdev_top->vdev_parent->vdev_parent == NULL);

	/*
	 * Walk up all ancestors to update guid sum.
	 */
	for (; pvd != NULL; pvd = pvd->vdev_parent)
		pvd->vdev_guid_sum += cvd->vdev_guid_sum;

	if (cvd->vdev_ops->vdev_op_leaf) {
		list_insert_head(&cvd->vdev_spa->spa_leaf_list, cvd);
		cvd->vdev_spa->spa_leaf_list_gen++;
	}
}

void
vdev_remove_child(vdev_t *pvd, vdev_t *cvd)
{
	int c;
	uint_t id = cvd->vdev_id;

	ASSERT(cvd->vdev_parent == pvd);

	if (pvd == NULL)
		return;

	ASSERT(id < pvd->vdev_children);
	ASSERT(pvd->vdev_child[id] == cvd);

	pvd->vdev_child[id] = NULL;
	cvd->vdev_parent = NULL;

	for (c = 0; c < pvd->vdev_children; c++)
		if (pvd->vdev_child[c])
			break;

	if (c == pvd->vdev_children) {
		kmem_free(pvd->vdev_child, c * sizeof (vdev_t *));
		pvd->vdev_child = NULL;
		pvd->vdev_children = 0;
	}

	if (cvd->vdev_ops->vdev_op_leaf) {
		spa_t *spa = cvd->vdev_spa;
		list_remove(&spa->spa_leaf_list, cvd);
		spa->spa_leaf_list_gen++;
	}

	/*
	 * Walk up all ancestors to update guid sum.
	 */
	for (; pvd != NULL; pvd = pvd->vdev_parent)
		pvd->vdev_guid_sum -= cvd->vdev_guid_sum;
}

/*
 * Remove any holes in the child array.
 */
void
vdev_compact_children(vdev_t *pvd)
{
	vdev_t **newchild, *cvd;
	int oldc = pvd->vdev_children;
	int newc;

	ASSERT(spa_config_held(pvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	for (int c = newc = 0; c < oldc; c++)
		if (pvd->vdev_child[c])
			newc++;

	newchild = kmem_alloc(newc * sizeof (vdev_t *), KM_SLEEP);

	for (int c = newc = 0; c < oldc; c++) {
		if ((cvd = pvd->vdev_child[c]) != NULL) {
			newchild[newc] = cvd;
			cvd->vdev_id = newc++;
		}
	}

	kmem_free(pvd->vdev_child, oldc * sizeof (vdev_t *));
	pvd->vdev_child = newchild;
	pvd->vdev_children = newc;
}

/*
 * Allocate and minimally initialize a vdev_t.
 */
vdev_t *
vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
{
	vdev_t *vd;
	vdev_indirect_config_t *vic;

	vd = kmem_zalloc(sizeof (vdev_t), KM_SLEEP);
	vic = &vd->vdev_indirect_config;

	if (spa->spa_root_vdev == NULL) {
		ASSERT(ops == &vdev_root_ops);
		spa->spa_root_vdev = vd;
		spa->spa_load_guid = spa_generate_guid(NULL);
	}

	if (guid == 0 && ops != &vdev_hole_ops) {
		if (spa->spa_root_vdev == vd) {
			/*
			 * The root vdev's guid will also be the pool guid,
			 * which must be unique among all pools.
			 */
			guid = spa_generate_guid(NULL);
		} else {
			/*
			 * Any other vdev's guid must be unique within the pool.
			 */
			guid = spa_generate_guid(spa);
		}
		ASSERT(!spa_guid_exists(spa_guid(spa), guid));
	}

	vd->vdev_spa = spa;
	vd->vdev_id = id;
	vd->vdev_guid = guid;
	vd->vdev_guid_sum = guid;
	vd->vdev_ops = ops;
	vd->vdev_state = VDEV_STATE_CLOSED;
	vd->vdev_ishole = (ops == &vdev_hole_ops);
	vic->vic_prev_indirect_vdev = UINT64_MAX;

	rw_init(&vd->vdev_indirect_rwlock, NULL, RW_DEFAULT, NULL);
	mutex_init(&vd->vdev_obsolete_lock, NULL, MUTEX_DEFAULT, NULL);
	vd->vdev_obsolete_segments = range_tree_create(NULL, RANGE_SEG64, NULL,
	    0, 0);

	list_link_init(&vd->vdev_initialize_node);
	list_link_init(&vd->vdev_leaf_node);
	list_link_init(&vd->vdev_trim_node);
	mutex_init(&vd->vdev_dtl_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_stat_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_probe_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_scan_io_queue_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_initialize_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_initialize_io_lock, NULL, MUTEX_DEFAULT, NULL);
	cv_init(&vd->vdev_initialize_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&vd->vdev_initialize_io_cv, NULL, CV_DEFAULT, NULL);
	mutex_init(&vd->vdev_trim_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_autotrim_lock, NULL, MUTEX_DEFAULT, NULL);
	mutex_init(&vd->vdev_trim_io_lock, NULL, MUTEX_DEFAULT, NULL);
	cv_init(&vd->vdev_trim_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&vd->vdev_autotrim_cv, NULL, CV_DEFAULT, NULL);
	cv_init(&vd->vdev_trim_io_cv, NULL, CV_DEFAULT, NULL);

	for (int t = 0; t < DTL_TYPES; t++) {
		vd->vdev_dtl[t] = range_tree_create(NULL, RANGE_SEG64, NULL, 0,
		    0);
	}
	txg_list_create(&vd->vdev_ms_list, spa,
	    offsetof(struct metaslab, ms_txg_node));
	txg_list_create(&vd->vdev_dtl_list, spa,
	    offsetof(struct vdev, vdev_dtl_node));
	vd->vdev_stat.vs_timestamp = gethrtime();
	vdev_queue_init(vd);
	vdev_cache_init(vd);

	return (vd);
}

/*
 * Allocate a new vdev.  The 'alloctype' is used to control whether we are
 * creating a new vdev or loading an existing one - the behavior is slightly
 * different for each case.
 */
int
vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
    int alloctype)
{
	vdev_ops_t *ops;
	char *type;
	uint64_t guid = 0, islog, nparity;
	vdev_t *vd;
	vdev_indirect_config_t *vic;
	vdev_alloc_bias_t alloc_bias = VDEV_BIAS_NONE;
	boolean_t top_level = (parent && !parent->vdev_parent);

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_TYPE, &type) != 0)
		return (SET_ERROR(EINVAL));

	if ((ops = vdev_getops(type)) == NULL)
		return (SET_ERROR(EINVAL));

	/*
	 * If this is a load, get the vdev guid from the nvlist.
	 * Otherwise, vdev_alloc_common() will generate one for us.
	 */
	if (alloctype == VDEV_ALLOC_LOAD) {
		uint64_t label_id;

		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ID, &label_id) ||
		    label_id != id)
			return (SET_ERROR(EINVAL));

		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
			return (SET_ERROR(EINVAL));
	} else if (alloctype == VDEV_ALLOC_SPARE) {
		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
			return (SET_ERROR(EINVAL));
	} else if (alloctype == VDEV_ALLOC_L2CACHE) {
		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
			return (SET_ERROR(EINVAL));
	} else if (alloctype == VDEV_ALLOC_ROOTPOOL) {
		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_GUID, &guid) != 0)
			return (SET_ERROR(EINVAL));
	}

	/*
	 * The first allocated vdev must be of type 'root'.
	 */
	if (ops != &vdev_root_ops && spa->spa_root_vdev == NULL)
		return (SET_ERROR(EINVAL));

	/*
	 * Determine whether we're a log vdev.
	 */
	islog = 0;
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_LOG, &islog);
	if (islog && spa_version(spa) < SPA_VERSION_SLOGS)
		return (SET_ERROR(ENOTSUP));

	if (ops == &vdev_hole_ops && spa_version(spa) < SPA_VERSION_HOLES)
		return (SET_ERROR(ENOTSUP));

	/*
	 * Set the nparity property for RAID-Z vdevs.
	 */
	nparity = -1ULL;
	if (ops == &vdev_raidz_ops) {
		if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NPARITY,
		    &nparity) == 0) {
			if (nparity == 0 || nparity > VDEV_RAIDZ_MAXPARITY)
				return (SET_ERROR(EINVAL));
			/*
			 * Previous versions could only support 1 or 2 parity
			 * device.
			 */
			if (nparity > 1 &&
			    spa_version(spa) < SPA_VERSION_RAIDZ2)
				return (SET_ERROR(ENOTSUP));
			if (nparity > 2 &&
			    spa_version(spa) < SPA_VERSION_RAIDZ3)
				return (SET_ERROR(ENOTSUP));
		} else {
			/*
			 * We require the parity to be specified for SPAs that
			 * support multiple parity levels.
			 */
			if (spa_version(spa) >= SPA_VERSION_RAIDZ2)
				return (SET_ERROR(EINVAL));
			/*
			 * Otherwise, we default to 1 parity device for RAID-Z.
			 */
			nparity = 1;
		}
	} else {
		nparity = 0;
	}
	ASSERT(nparity != -1ULL);

	/*
	 * If creating a top-level vdev, check for allocation classes input
	 */
	if (top_level && alloctype == VDEV_ALLOC_ADD) {
		char *bias;

		if (nvlist_lookup_string(nv, ZPOOL_CONFIG_ALLOCATION_BIAS,
		    &bias) == 0) {
			alloc_bias = vdev_derive_alloc_bias(bias);

			/* spa_vdev_add() expects feature to be enabled */
			if (alloc_bias != VDEV_BIAS_LOG &&
			    spa->spa_load_state != SPA_LOAD_CREATE &&
			    !spa_feature_is_enabled(spa,
			    SPA_FEATURE_ALLOCATION_CLASSES)) {
				return (SET_ERROR(ENOTSUP));
			}
		}
	}

	vd = vdev_alloc_common(spa, id, guid, ops);
	vic = &vd->vdev_indirect_config;

	vd->vdev_islog = islog;
	vd->vdev_nparity = nparity;
	if (top_level && alloc_bias != VDEV_BIAS_NONE)
		vd->vdev_alloc_bias = alloc_bias;

	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &vd->vdev_path) == 0)
		vd->vdev_path = spa_strdup(vd->vdev_path);
	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_DEVID, &vd->vdev_devid) == 0)
		vd->vdev_devid = spa_strdup(vd->vdev_devid);
	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PHYS_PATH,
	    &vd->vdev_physpath) == 0)
		vd->vdev_physpath = spa_strdup(vd->vdev_physpath);
	if (nvlist_lookup_string(nv, ZPOOL_CONFIG_FRU, &vd->vdev_fru) == 0)
		vd->vdev_fru = spa_strdup(vd->vdev_fru);

	/*
	 * Set the whole_disk property.  If it's not specified, leave the value
	 * as -1.
	 */
	if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_WHOLE_DISK,
	    &vd->vdev_wholedisk) != 0)
		vd->vdev_wholedisk = -1ULL;

	ASSERT0(vic->vic_mapping_object);
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_INDIRECT_OBJECT,
	    &vic->vic_mapping_object);
	ASSERT0(vic->vic_births_object);
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_INDIRECT_BIRTHS,
	    &vic->vic_births_object);
	ASSERT3U(vic->vic_prev_indirect_vdev, ==, UINT64_MAX);
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
	    &vic->vic_prev_indirect_vdev);

	/*
	 * Look for the 'not present' flag.  This will only be set if the device
	 * was not present at the time of import.
	 */
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_NOT_PRESENT,
	    &vd->vdev_not_present);

	/*
	 * Get the alignment requirement.
	 */
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASHIFT, &vd->vdev_ashift);

	/*
	 * Retrieve the vdev creation time.
	 */
	(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_CREATE_TXG,
	    &vd->vdev_crtxg);

	/*
	 * If we're a top-level vdev, try to load the allocation parameters.
	 */
	if (top_level &&
	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
		    &vd->vdev_ms_array);
		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_SHIFT,
		    &vd->vdev_ms_shift);
		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_ASIZE,
		    &vd->vdev_asize);
		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVING,
		    &vd->vdev_removing);
		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_VDEV_TOP_ZAP,
		    &vd->vdev_top_zap);
	} else {
		ASSERT0(vd->vdev_top_zap);
	}

	if (top_level && alloctype != VDEV_ALLOC_ATTACH) {
		ASSERT(alloctype == VDEV_ALLOC_LOAD ||
		    alloctype == VDEV_ALLOC_ADD ||
		    alloctype == VDEV_ALLOC_SPLIT ||
		    alloctype == VDEV_ALLOC_ROOTPOOL);
		/* Note: metaslab_group_create() is now deferred */
	}

	if (vd->vdev_ops->vdev_op_leaf &&
	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
		(void) nvlist_lookup_uint64(nv,
		    ZPOOL_CONFIG_VDEV_LEAF_ZAP, &vd->vdev_leaf_zap);
	} else {
		ASSERT0(vd->vdev_leaf_zap);
	}

	/*
	 * If we're a leaf vdev, try to load the DTL object and other state.
	 */

	if (vd->vdev_ops->vdev_op_leaf &&
	    (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_L2CACHE ||
	    alloctype == VDEV_ALLOC_ROOTPOOL)) {
		if (alloctype == VDEV_ALLOC_LOAD) {
			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DTL,
			    &vd->vdev_dtl_object);
			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_UNSPARE,
			    &vd->vdev_unspare);
		}

		if (alloctype == VDEV_ALLOC_ROOTPOOL) {
			uint64_t spare = 0;

			if (nvlist_lookup_uint64(nv, ZPOOL_CONFIG_IS_SPARE,
			    &spare) == 0 && spare)
				spa_spare_add(vd);
		}

		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_OFFLINE,
		    &vd->vdev_offline);

		(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
		    &vd->vdev_resilver_txg);

		if (nvlist_exists(nv, ZPOOL_CONFIG_RESILVER_DEFER))
			vdev_defer_resilver(vd);

		/*
		 * When importing a pool, we want to ignore the persistent fault
		 * state, as the diagnosis made on another system may not be
		 * valid in the current context.  Local vdevs will
		 * remain in the faulted state.
		 */
		if (spa_load_state(spa) == SPA_LOAD_OPEN) {
			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_FAULTED,
			    &vd->vdev_faulted);
			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DEGRADED,
			    &vd->vdev_degraded);
			(void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_REMOVED,
			    &vd->vdev_removed);

			if (vd->vdev_faulted || vd->vdev_degraded) {
				char *aux;

				vd->vdev_label_aux =
				    VDEV_AUX_ERR_EXCEEDED;
				if (nvlist_lookup_string(nv,
				    ZPOOL_CONFIG_AUX_STATE, &aux) == 0 &&
				    strcmp(aux, "external") == 0)
					vd->vdev_label_aux = VDEV_AUX_EXTERNAL;
			}
		}
	}

	/*
	 * Add ourselves to the parent's list of children.
	 */
	vdev_add_child(parent, vd);

	*vdp = vd;

	return (0);
}

void
vdev_free(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;

	ASSERT3P(vd->vdev_initialize_thread, ==, NULL);
	ASSERT3P(vd->vdev_trim_thread, ==, NULL);
	ASSERT3P(vd->vdev_autotrim_thread, ==, NULL);

	/*
	 * Scan queues are normally destroyed at the end of a scan. If the
	 * queue exists here, that implies the vdev is being removed while
	 * the scan is still running.
	 */
	if (vd->vdev_scan_io_queue != NULL) {
		mutex_enter(&vd->vdev_scan_io_queue_lock);
		dsl_scan_io_queue_destroy(vd->vdev_scan_io_queue);
		vd->vdev_scan_io_queue = NULL;
		mutex_exit(&vd->vdev_scan_io_queue_lock);
	}

	/*
	 * vdev_free() implies closing the vdev first.  This is simpler than
	 * trying to ensure complicated semantics for all callers.
	 */
	vdev_close(vd);

	ASSERT(!list_link_active(&vd->vdev_config_dirty_node));
	ASSERT(!list_link_active(&vd->vdev_state_dirty_node));

	/*
	 * Free all children.
	 */
	for (int c = 0; c < vd->vdev_children; c++)
		vdev_free(vd->vdev_child[c]);

	ASSERT(vd->vdev_child == NULL);
	ASSERT(vd->vdev_guid_sum == vd->vdev_guid);

	/*
	 * Discard allocation state.
	 */
	if (vd->vdev_mg != NULL) {
		vdev_metaslab_fini(vd);
		metaslab_group_destroy(vd->vdev_mg);
		vd->vdev_mg = NULL;
	}

	ASSERT0(vd->vdev_stat.vs_space);
	ASSERT0(vd->vdev_stat.vs_dspace);
	ASSERT0(vd->vdev_stat.vs_alloc);

	/*
	 * Remove this vdev from its parent's child list.
	 */
	vdev_remove_child(vd->vdev_parent, vd);

	ASSERT(vd->vdev_parent == NULL);
	ASSERT(!list_link_active(&vd->vdev_leaf_node));

	/*
	 * Clean up vdev structure.
	 */
	vdev_queue_fini(vd);
	vdev_cache_fini(vd);

	if (vd->vdev_path)
		spa_strfree(vd->vdev_path);
	if (vd->vdev_devid)
		spa_strfree(vd->vdev_devid);
	if (vd->vdev_physpath)
		spa_strfree(vd->vdev_physpath);
	if (vd->vdev_fru)
		spa_strfree(vd->vdev_fru);

	if (vd->vdev_isspare)
		spa_spare_remove(vd);
	if (vd->vdev_isl2cache)
		spa_l2cache_remove(vd);

	txg_list_destroy(&vd->vdev_ms_list);
	txg_list_destroy(&vd->vdev_dtl_list);

	mutex_enter(&vd->vdev_dtl_lock);
	space_map_close(vd->vdev_dtl_sm);
	for (int t = 0; t < DTL_TYPES; t++) {
		range_tree_vacate(vd->vdev_dtl[t], NULL, NULL);
		range_tree_destroy(vd->vdev_dtl[t]);
	}
	mutex_exit(&vd->vdev_dtl_lock);

	EQUIV(vd->vdev_indirect_births != NULL,
	    vd->vdev_indirect_mapping != NULL);
	if (vd->vdev_indirect_births != NULL) {
		vdev_indirect_mapping_close(vd->vdev_indirect_mapping);
		vdev_indirect_births_close(vd->vdev_indirect_births);
	}

	if (vd->vdev_obsolete_sm != NULL) {
		ASSERT(vd->vdev_removing ||
		    vd->vdev_ops == &vdev_indirect_ops);
		space_map_close(vd->vdev_obsolete_sm);
		vd->vdev_obsolete_sm = NULL;
	}
	range_tree_destroy(vd->vdev_obsolete_segments);
	rw_destroy(&vd->vdev_indirect_rwlock);
	mutex_destroy(&vd->vdev_obsolete_lock);

	mutex_destroy(&vd->vdev_dtl_lock);
	mutex_destroy(&vd->vdev_stat_lock);
	mutex_destroy(&vd->vdev_probe_lock);
	mutex_destroy(&vd->vdev_scan_io_queue_lock);
	mutex_destroy(&vd->vdev_initialize_lock);
	mutex_destroy(&vd->vdev_initialize_io_lock);
	cv_destroy(&vd->vdev_initialize_io_cv);
	cv_destroy(&vd->vdev_initialize_cv);
	mutex_destroy(&vd->vdev_trim_lock);
	mutex_destroy(&vd->vdev_autotrim_lock);
	mutex_destroy(&vd->vdev_trim_io_lock);
	cv_destroy(&vd->vdev_trim_cv);
	cv_destroy(&vd->vdev_autotrim_cv);
	cv_destroy(&vd->vdev_trim_io_cv);

	if (vd == spa->spa_root_vdev)
		spa->spa_root_vdev = NULL;

	kmem_free(vd, sizeof (vdev_t));
}

/*
 * Transfer top-level vdev state from svd to tvd.
 */
static void
vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
{
	spa_t *spa = svd->vdev_spa;
	metaslab_t *msp;
	vdev_t *vd;
	int t;

	ASSERT(tvd == tvd->vdev_top);

	tvd->vdev_ms_array = svd->vdev_ms_array;
	tvd->vdev_ms_shift = svd->vdev_ms_shift;
	tvd->vdev_ms_count = svd->vdev_ms_count;
	tvd->vdev_top_zap = svd->vdev_top_zap;

	svd->vdev_ms_array = 0;
	svd->vdev_ms_shift = 0;
	svd->vdev_ms_count = 0;
	svd->vdev_top_zap = 0;

	if (tvd->vdev_mg)
		ASSERT3P(tvd->vdev_mg, ==, svd->vdev_mg);
	tvd->vdev_mg = svd->vdev_mg;
	tvd->vdev_ms = svd->vdev_ms;

	svd->vdev_mg = NULL;
	svd->vdev_ms = NULL;

	if (tvd->vdev_mg != NULL)
		tvd->vdev_mg->mg_vd = tvd;

	tvd->vdev_checkpoint_sm = svd->vdev_checkpoint_sm;
	svd->vdev_checkpoint_sm = NULL;

	tvd->vdev_alloc_bias = svd->vdev_alloc_bias;
	svd->vdev_alloc_bias = VDEV_BIAS_NONE;

	tvd->vdev_stat.vs_alloc = svd->vdev_stat.vs_alloc;
	tvd->vdev_stat.vs_space = svd->vdev_stat.vs_space;
	tvd->vdev_stat.vs_dspace = svd->vdev_stat.vs_dspace;

	svd->vdev_stat.vs_alloc = 0;
	svd->vdev_stat.vs_space = 0;
	svd->vdev_stat.vs_dspace = 0;

	/*
	 * State which may be set on a top-level vdev that's in the
	 * process of being removed.
	 */
	ASSERT0(tvd->vdev_indirect_config.vic_births_object);
	ASSERT0(tvd->vdev_indirect_config.vic_mapping_object);
	ASSERT3U(tvd->vdev_indirect_config.vic_prev_indirect_vdev, ==, -1ULL);
	ASSERT3P(tvd->vdev_indirect_mapping, ==, NULL);
	ASSERT3P(tvd->vdev_indirect_births, ==, NULL);
	ASSERT3P(tvd->vdev_obsolete_sm, ==, NULL);
	ASSERT0(tvd->vdev_removing);
	tvd->vdev_removing = svd->vdev_removing;
	tvd->vdev_indirect_config = svd->vdev_indirect_config;
	tvd->vdev_indirect_mapping = svd->vdev_indirect_mapping;
	tvd->vdev_indirect_births = svd->vdev_indirect_births;
	range_tree_swap(&svd->vdev_obsolete_segments,
	    &tvd->vdev_obsolete_segments);
	tvd->vdev_obsolete_sm = svd->vdev_obsolete_sm;
	svd->vdev_indirect_config.vic_mapping_object = 0;
	svd->vdev_indirect_config.vic_births_object = 0;
	svd->vdev_indirect_config.vic_prev_indirect_vdev = -1ULL;
	svd->vdev_indirect_mapping = NULL;
	svd->vdev_indirect_births = NULL;
	svd->vdev_obsolete_sm = NULL;
	svd->vdev_removing = 0;

	for (t = 0; t < TXG_SIZE; t++) {
		while ((msp = txg_list_remove(&svd->vdev_ms_list, t)) != NULL)
			(void) txg_list_add(&tvd->vdev_ms_list, msp, t);
		while ((vd = txg_list_remove(&svd->vdev_dtl_list, t)) != NULL)
			(void) txg_list_add(&tvd->vdev_dtl_list, vd, t);
		if (txg_list_remove_this(&spa->spa_vdev_txg_list, svd, t))
			(void) txg_list_add(&spa->spa_vdev_txg_list, tvd, t);
	}

	if (list_link_active(&svd->vdev_config_dirty_node)) {
		vdev_config_clean(svd);
		vdev_config_dirty(tvd);
	}

	if (list_link_active(&svd->vdev_state_dirty_node)) {
		vdev_state_clean(svd);
		vdev_state_dirty(tvd);
	}

	tvd->vdev_deflate_ratio = svd->vdev_deflate_ratio;
	svd->vdev_deflate_ratio = 0;

	tvd->vdev_islog = svd->vdev_islog;
	svd->vdev_islog = 0;

	dsl_scan_io_queue_vdev_xfer(svd, tvd);
}

static void
vdev_top_update(vdev_t *tvd, vdev_t *vd)
{
	if (vd == NULL)
		return;

	vd->vdev_top = tvd;

	for (int c = 0; c < vd->vdev_children; c++)
		vdev_top_update(tvd, vd->vdev_child[c]);
}

/*
 * Add a mirror/replacing vdev above an existing vdev.
 */
vdev_t *
vdev_add_parent(vdev_t *cvd, vdev_ops_t *ops)
{
	spa_t *spa = cvd->vdev_spa;
	vdev_t *pvd = cvd->vdev_parent;
	vdev_t *mvd;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	mvd = vdev_alloc_common(spa, cvd->vdev_id, 0, ops);

	mvd->vdev_asize = cvd->vdev_asize;
	mvd->vdev_min_asize = cvd->vdev_min_asize;
	mvd->vdev_max_asize = cvd->vdev_max_asize;
	mvd->vdev_psize = cvd->vdev_psize;
	mvd->vdev_ashift = cvd->vdev_ashift;
	mvd->vdev_state = cvd->vdev_state;
	mvd->vdev_crtxg = cvd->vdev_crtxg;

	vdev_remove_child(pvd, cvd);
	vdev_add_child(pvd, mvd);
	cvd->vdev_id = mvd->vdev_children;
	vdev_add_child(mvd, cvd);
	vdev_top_update(cvd->vdev_top, cvd->vdev_top);

	if (mvd == mvd->vdev_top)
		vdev_top_transfer(cvd, mvd);

	return (mvd);
}

/*
 * Remove a 1-way mirror/replacing vdev from the tree.
 */
void
vdev_remove_parent(vdev_t *cvd)
{
	vdev_t *mvd = cvd->vdev_parent;
	vdev_t *pvd = mvd->vdev_parent;

	ASSERT(spa_config_held(cvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);

	ASSERT(mvd->vdev_children == 1);
	ASSERT(mvd->vdev_ops == &vdev_mirror_ops ||
	    mvd->vdev_ops == &vdev_replacing_ops ||
	    mvd->vdev_ops == &vdev_spare_ops);
	cvd->vdev_ashift = mvd->vdev_ashift;

	vdev_remove_child(mvd, cvd);
	vdev_remove_child(pvd, mvd);

	/*
	 * If cvd will replace mvd as a top-level vdev, preserve mvd's guid.
	 * Otherwise, we could have detached an offline device, and when we
	 * go to import the pool we'll think we have two top-level vdevs,
	 * instead of a different version of the same top-level vdev.
	 */
	if (mvd->vdev_top == mvd) {
		uint64_t guid_delta = mvd->vdev_guid - cvd->vdev_guid;
		cvd->vdev_orig_guid = cvd->vdev_guid;
		cvd->vdev_guid += guid_delta;
		cvd->vdev_guid_sum += guid_delta;
	}
	cvd->vdev_id = mvd->vdev_id;
	vdev_add_child(pvd, cvd);
	vdev_top_update(cvd->vdev_top, cvd->vdev_top);

	if (cvd == cvd->vdev_top)
		vdev_top_transfer(mvd, cvd);

	ASSERT(mvd->vdev_children == 0);
	vdev_free(mvd);
}

static void
vdev_metaslab_group_create(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;

	/*
	 * metaslab_group_create was delayed until allocation bias was available
	 */
	if (vd->vdev_mg == NULL) {
		metaslab_class_t *mc;

		if (vd->vdev_islog && vd->vdev_alloc_bias == VDEV_BIAS_NONE)
			vd->vdev_alloc_bias = VDEV_BIAS_LOG;

		ASSERT3U(vd->vdev_islog, ==,
		    (vd->vdev_alloc_bias == VDEV_BIAS_LOG));

		switch (vd->vdev_alloc_bias) {
		case VDEV_BIAS_LOG:
			mc = spa_log_class(spa);
			break;
		case VDEV_BIAS_SPECIAL:
			mc = spa_special_class(spa);
			break;
		case VDEV_BIAS_DEDUP:
			mc = spa_dedup_class(spa);
			break;
		default:
			mc = spa_normal_class(spa);
		}

		vd->vdev_mg = metaslab_group_create(mc, vd,
		    spa->spa_alloc_count);

		/*
		 * The spa ashift values currently only reflect the
		 * general vdev classes. Class destination is late
		 * binding so ashift checking had to wait until now
		 */
		if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
		    mc == spa_normal_class(spa) && vd->vdev_aux == NULL) {
			if (vd->vdev_ashift > spa->spa_max_ashift)
				spa->spa_max_ashift = vd->vdev_ashift;
			if (vd->vdev_ashift < spa->spa_min_ashift)
				spa->spa_min_ashift = vd->vdev_ashift;
		}
	}
}

int
vdev_metaslab_init(vdev_t *vd, uint64_t txg)
{
	spa_t *spa = vd->vdev_spa;
	objset_t *mos = spa->spa_meta_objset;
	uint64_t m;
	uint64_t oldc = vd->vdev_ms_count;
	uint64_t newc = vd->vdev_asize >> vd->vdev_ms_shift;
	metaslab_t **mspp;
	int error;
	boolean_t expanding = (oldc != 0);

	ASSERT(txg == 0 || spa_config_held(spa, SCL_ALLOC, RW_WRITER));

	/*
	 * This vdev is not being allocated from yet or is a hole.
	 */
	if (vd->vdev_ms_shift == 0)
		return (0);

	ASSERT(!vd->vdev_ishole);

	ASSERT(oldc <= newc);

	mspp = kmem_zalloc(newc * sizeof (*mspp), KM_SLEEP);

	if (expanding) {
		bcopy(vd->vdev_ms, mspp, oldc * sizeof (*mspp));
		kmem_free(vd->vdev_ms, oldc * sizeof (*mspp));
	}

	vd->vdev_ms = mspp;
	vd->vdev_ms_count = newc;
	for (m = oldc; m < newc; m++) {
		uint64_t object = 0;

		/*
		 * vdev_ms_array may be 0 if we are creating the "fake"
		 * metaslabs for an indirect vdev for zdb's leak detection.
		 * See zdb_leak_init().
		 */
		if (txg == 0 && vd->vdev_ms_array != 0) {
			error = dmu_read(mos, vd->vdev_ms_array,
			    m * sizeof (uint64_t), sizeof (uint64_t), &object,
			    DMU_READ_PREFETCH);
			if (error != 0) {
				vdev_dbgmsg(vd, "unable to read the metaslab "
				    "array [error=%d]", error);
				return (error);
			}
		}

#ifndef _KERNEL
		/*
		 * To accomodate zdb_leak_init() fake indirect
		 * metaslabs, we allocate a metaslab group for
		 * indirect vdevs which normally don't have one.
		 */
		if (vd->vdev_mg == NULL) {
			ASSERT0(vdev_is_concrete(vd));
			vdev_metaslab_group_create(vd);
		}
#endif
		error = metaslab_init(vd->vdev_mg, m, object, txg,
		    &(vd->vdev_ms[m]));
		if (error != 0) {
			vdev_dbgmsg(vd, "metaslab_init failed [error=%d]",
			    error);
			return (error);
		}
	}

	if (txg == 0)
		spa_config_enter(spa, SCL_ALLOC, FTAG, RW_WRITER);

	/*
	 * If the vdev is being removed we don't activate
	 * the metaslabs since we want to ensure that no new
	 * allocations are performed on this device.
	 */
	if (!expanding && !vd->vdev_removing) {
		metaslab_group_activate(vd->vdev_mg);
	}

	if (txg == 0)
		spa_config_exit(spa, SCL_ALLOC, FTAG);

	/*
	 * Regardless whether this vdev was just added or it is being
	 * expanded, the metaslab count has changed. Recalculate the
	 * block limit.
	 */
	spa_log_sm_set_blocklimit(spa);

	return (0);
}

void
vdev_metaslab_fini(vdev_t *vd)
{
	if (vd->vdev_checkpoint_sm != NULL) {
		ASSERT(spa_feature_is_active(vd->vdev_spa,
		    SPA_FEATURE_POOL_CHECKPOINT));
		space_map_close(vd->vdev_checkpoint_sm);
		/*
		 * Even though we close the space map, we need to set its
		 * pointer to NULL. The reason is that vdev_metaslab_fini()
		 * may be called multiple times for certain operations
		 * (i.e. when destroying a pool) so we need to ensure that
		 * this clause never executes twice. This logic is similar
		 * to the one used for the vdev_ms clause below.
		 */
		vd->vdev_checkpoint_sm = NULL;
	}

	if (vd->vdev_ms != NULL) {
		metaslab_group_t *mg = vd->vdev_mg;
		metaslab_group_passivate(mg);

		uint64_t count = vd->vdev_ms_count;
		for (uint64_t m = 0; m < count; m++) {
			metaslab_t *msp = vd->vdev_ms[m];
			if (msp != NULL)
				metaslab_fini(msp);
		}
		kmem_free(vd->vdev_ms, count * sizeof (metaslab_t *));
		vd->vdev_ms = NULL;

		vd->vdev_ms_count = 0;

		for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
			ASSERT0(mg->mg_histogram[i]);
	}
	ASSERT0(vd->vdev_ms_count);
}

typedef struct vdev_probe_stats {
	boolean_t	vps_readable;
	boolean_t	vps_writeable;
	int		vps_flags;
} vdev_probe_stats_t;

static void
vdev_probe_done(zio_t *zio)
{
	spa_t *spa = zio->io_spa;
	vdev_t *vd = zio->io_vd;
	vdev_probe_stats_t *vps = zio->io_private;

	ASSERT(vd->vdev_probe_zio != NULL);

	if (zio->io_type == ZIO_TYPE_READ) {
		if (zio->io_error == 0)
			vps->vps_readable = 1;
		if (zio->io_error == 0 && spa_writeable(spa)) {
			zio_nowait(zio_write_phys(vd->vdev_probe_zio, vd,
			    zio->io_offset, zio->io_size, zio->io_abd,
			    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
			    ZIO_PRIORITY_SYNC_WRITE, vps->vps_flags, B_TRUE));
		} else {
			abd_free(zio->io_abd);
		}
	} else if (zio->io_type == ZIO_TYPE_WRITE) {
		if (zio->io_error == 0)
			vps->vps_writeable = 1;
		abd_free(zio->io_abd);
	} else if (zio->io_type == ZIO_TYPE_NULL) {
		zio_t *pio;

		vd->vdev_cant_read |= !vps->vps_readable;
		vd->vdev_cant_write |= !vps->vps_writeable;

		if (vdev_readable(vd) &&
		    (vdev_writeable(vd) || !spa_writeable(spa))) {
			zio->io_error = 0;
		} else {
			ASSERT(zio->io_error != 0);
			vdev_dbgmsg(vd, "failed probe");
			(void) zfs_ereport_post(FM_EREPORT_ZFS_PROBE_FAILURE,
			    spa, vd, NULL, NULL, 0, 0);
			zio->io_error = SET_ERROR(ENXIO);
		}

		mutex_enter(&vd->vdev_probe_lock);
		ASSERT(vd->vdev_probe_zio == zio);
		vd->vdev_probe_zio = NULL;
		mutex_exit(&vd->vdev_probe_lock);

		zio_link_t *zl = NULL;
		while ((pio = zio_walk_parents(zio, &zl)) != NULL)
			if (!vdev_accessible(vd, pio))
				pio->io_error = SET_ERROR(ENXIO);

		kmem_free(vps, sizeof (*vps));
	}
}

/*
 * Determine whether this device is accessible.
 *
 * Read and write to several known locations: the pad regions of each
 * vdev label but the first, which we leave alone in case it contains
 * a VTOC.
 */
zio_t *
vdev_probe(vdev_t *vd, zio_t *zio)
{
	spa_t *spa = vd->vdev_spa;
	vdev_probe_stats_t *vps = NULL;
	zio_t *pio;

	ASSERT(vd->vdev_ops->vdev_op_leaf);

	/*
	 * Don't probe the probe.
	 */
	if (zio && (zio->io_flags & ZIO_FLAG_PROBE))
		return (NULL);

	/*
	 * To prevent 'probe storms' when a device fails, we create
	 * just one probe i/o at a time.  All zios that want to probe
	 * this vdev will become parents of the probe io.
	 */
	mutex_enter(&vd->vdev_probe_lock);

	if ((pio = vd->vdev_probe_zio) == NULL) {
		vps = kmem_zalloc(sizeof (*vps), KM_SLEEP);

		vps->vps_flags = ZIO_FLAG_CANFAIL | ZIO_FLAG_PROBE |
		    ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_AGGREGATE |
		    ZIO_FLAG_TRYHARD;

		if (spa_config_held(spa, SCL_ZIO, RW_WRITER)) {
			/*
			 * vdev_cant_read and vdev_cant_write can only
			 * transition from TRUE to FALSE when we have the
			 * SCL_ZIO lock as writer; otherwise they can only
			 * transition from FALSE to TRUE.  This ensures that
			 * any zio looking at these values can assume that
			 * failures persist for the life of the I/O.  That's
			 * important because when a device has intermittent
			 * connectivity problems, we want to ensure that
			 * they're ascribed to the device (ENXIO) and not
			 * the zio (EIO).
			 *
			 * Since we hold SCL_ZIO as writer here, clear both
			 * values so the probe can reevaluate from first
			 * principles.
			 */
			vps->vps_flags |= ZIO_FLAG_CONFIG_WRITER;
			vd->vdev_cant_read = B_FALSE;
			vd->vdev_cant_write = B_FALSE;
		}

		vd->vdev_probe_zio = pio = zio_null(NULL, spa, vd,
		    vdev_probe_done, vps,
		    vps->vps_flags | ZIO_FLAG_DONT_PROPAGATE);

		/*
		 * We can't change the vdev state in this context, so we
		 * kick off an async task to do it on our behalf.
		 */
		if (zio != NULL) {
			vd->vdev_probe_wanted = B_TRUE;
			spa_async_request(spa, SPA_ASYNC_PROBE);
		}
	}

	if (zio != NULL)
		zio_add_child(zio, pio);

	mutex_exit(&vd->vdev_probe_lock);

	if (vps == NULL) {
		ASSERT(zio != NULL);
		return (NULL);
	}

	for (int l = 1; l < VDEV_LABELS; l++) {
		zio_nowait(zio_read_phys(pio, vd,
		    vdev_label_offset(vd->vdev_psize, l,
		    offsetof(vdev_label_t, vl_be)), VDEV_PAD_SIZE,
		    abd_alloc_for_io(VDEV_PAD_SIZE, B_TRUE),
		    ZIO_CHECKSUM_OFF, vdev_probe_done, vps,
		    ZIO_PRIORITY_SYNC_READ, vps->vps_flags, B_TRUE));
	}

	if (zio == NULL)
		return (pio);

	zio_nowait(pio);
	return (NULL);
}

static void
vdev_open_child(void *arg)
{
	vdev_t *vd = arg;

	vd->vdev_open_thread = curthread;
	vd->vdev_open_error = vdev_open(vd);
	vd->vdev_open_thread = NULL;
}

boolean_t
vdev_uses_zvols(vdev_t *vd)
{
	if (vd->vdev_path && strncmp(vd->vdev_path, ZVOL_DIR,
	    strlen(ZVOL_DIR)) == 0)
		return (B_TRUE);
	for (int c = 0; c < vd->vdev_children; c++)
		if (vdev_uses_zvols(vd->vdev_child[c]))
			return (B_TRUE);
	return (B_FALSE);
}

void
vdev_open_children(vdev_t *vd)
{
	taskq_t *tq;
	int children = vd->vdev_children;

	/*
	 * in order to handle pools on top of zvols, do the opens
	 * in a single thread so that the same thread holds the
	 * spa_namespace_lock
	 */
	if (vdev_uses_zvols(vd)) {
retry_sync:
		for (int c = 0; c < children; c++)
			vd->vdev_child[c]->vdev_open_error =
			    vdev_open(vd->vdev_child[c]);
	} else {
		tq = taskq_create("vdev_open", children, minclsyspri,
		    children, children, TASKQ_PREPOPULATE);
		if (tq == NULL)
			goto retry_sync;

		for (int c = 0; c < children; c++)
			VERIFY(taskq_dispatch(tq, vdev_open_child,
			    vd->vdev_child[c], TQ_SLEEP) != TASKQID_INVALID);

		taskq_destroy(tq);
	}

	vd->vdev_nonrot = B_TRUE;

	for (int c = 0; c < children; c++)
		vd->vdev_nonrot &= vd->vdev_child[c]->vdev_nonrot;
}

/*
 * Compute the raidz-deflation ratio.  Note, we hard-code
 * in 128k (1 << 17) because it is the "typical" blocksize.
 * Even though SPA_MAXBLOCKSIZE changed, this algorithm can not change,
 * otherwise it would inconsistently account for existing bp's.
 */
static void
vdev_set_deflate_ratio(vdev_t *vd)
{
	if (vd == vd->vdev_top && !vd->vdev_ishole && vd->vdev_ashift != 0) {
		vd->vdev_deflate_ratio = (1 << 17) /
		    (vdev_psize_to_asize(vd, 1 << 17) >> SPA_MINBLOCKSHIFT);
	}
}

/*
 * Prepare a virtual device for access.
 */
int
vdev_open(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	int error;
	uint64_t osize = 0;
	uint64_t max_osize = 0;
	uint64_t asize, max_asize, psize;
	uint64_t ashift = 0;

	ASSERT(vd->vdev_open_thread == curthread ||
	    spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
	ASSERT(vd->vdev_state == VDEV_STATE_CLOSED ||
	    vd->vdev_state == VDEV_STATE_CANT_OPEN ||
	    vd->vdev_state == VDEV_STATE_OFFLINE);

	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
	vd->vdev_cant_read = B_FALSE;
	vd->vdev_cant_write = B_FALSE;
	vd->vdev_min_asize = vdev_get_min_asize(vd);

	/*
	 * If this vdev is not removed, check its fault status.  If it's
	 * faulted, bail out of the open.
	 */
	if (!vd->vdev_removed && vd->vdev_faulted) {
		ASSERT(vd->vdev_children == 0);
		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
		    vd->vdev_label_aux);
		return (SET_ERROR(ENXIO));
	} else if (vd->vdev_offline) {
		ASSERT(vd->vdev_children == 0);
		vdev_set_state(vd, B_TRUE, VDEV_STATE_OFFLINE, VDEV_AUX_NONE);
		return (SET_ERROR(ENXIO));
	}

	error = vd->vdev_ops->vdev_op_open(vd, &osize, &max_osize, &ashift);

	/*
	 * Reset the vdev_reopening flag so that we actually close
	 * the vdev on error.
	 */
	vd->vdev_reopening = B_FALSE;
	if (zio_injection_enabled && error == 0)
		error = zio_handle_device_injection(vd, NULL, ENXIO);

	if (error) {
		if (vd->vdev_removed &&
		    vd->vdev_stat.vs_aux != VDEV_AUX_OPEN_FAILED)
			vd->vdev_removed = B_FALSE;

		if (vd->vdev_stat.vs_aux == VDEV_AUX_CHILDREN_OFFLINE) {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_OFFLINE,
			    vd->vdev_stat.vs_aux);
		} else {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
			    vd->vdev_stat.vs_aux);
		}
		return (error);
	}

	vd->vdev_removed = B_FALSE;

	/*
	 * Recheck the faulted flag now that we have confirmed that
	 * the vdev is accessible.  If we're faulted, bail.
	 */
	if (vd->vdev_faulted) {
		ASSERT(vd->vdev_children == 0);
		ASSERT(vd->vdev_label_aux == VDEV_AUX_ERR_EXCEEDED ||
		    vd->vdev_label_aux == VDEV_AUX_EXTERNAL);
		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
		    vd->vdev_label_aux);
		return (SET_ERROR(ENXIO));
	}

	if (vd->vdev_degraded) {
		ASSERT(vd->vdev_children == 0);
		vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
		    VDEV_AUX_ERR_EXCEEDED);
	} else {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_HEALTHY, 0);
	}

	/*
	 * For hole or missing vdevs we just return success.
	 */
	if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops)
		return (0);

	for (int c = 0; c < vd->vdev_children; c++) {
		if (vd->vdev_child[c]->vdev_state != VDEV_STATE_HEALTHY) {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
			    VDEV_AUX_NONE);
			break;
		}
	}

	osize = P2ALIGN(osize, (uint64_t)sizeof (vdev_label_t));
	max_osize = P2ALIGN(max_osize, (uint64_t)sizeof (vdev_label_t));

	if (vd->vdev_children == 0) {
		if (osize < SPA_MINDEVSIZE) {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_TOO_SMALL);
			return (SET_ERROR(EOVERFLOW));
		}
		psize = osize;
		asize = osize - (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE);
		max_asize = max_osize - (VDEV_LABEL_START_SIZE +
		    VDEV_LABEL_END_SIZE);
	} else {
		if (vd->vdev_parent != NULL && osize < SPA_MINDEVSIZE -
		    (VDEV_LABEL_START_SIZE + VDEV_LABEL_END_SIZE)) {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_TOO_SMALL);
			return (SET_ERROR(EOVERFLOW));
		}
		psize = 0;
		asize = osize;
		max_asize = max_osize;
	}

	vd->vdev_psize = psize;

	/*
	 * Make sure the allocatable size hasn't shrunk too much.
	 */
	if (asize < vd->vdev_min_asize) {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_BAD_LABEL);
		return (SET_ERROR(EINVAL));
	}

	if (vd->vdev_asize == 0) {
		/*
		 * This is the first-ever open, so use the computed values.
		 * For compatibility, a different ashift can be requested.
		 */
		vd->vdev_asize = asize;
		vd->vdev_max_asize = max_asize;
		if (vd->vdev_ashift == 0) {
			vd->vdev_ashift = ashift; /* use detected value */
		}
		if (vd->vdev_ashift != 0 && (vd->vdev_ashift < ASHIFT_MIN ||
		    vd->vdev_ashift > ASHIFT_MAX)) {
			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_BAD_ASHIFT);
			return (SET_ERROR(EDOM));
		}
	} else {
		/*
		 * Detect if the alignment requirement has increased.
		 * We don't want to make the pool unavailable, just
		 * post an event instead.
		 */
		if (ashift > vd->vdev_top->vdev_ashift &&
		    vd->vdev_ops->vdev_op_leaf) {
			(void) zfs_ereport_post(
			    FM_EREPORT_ZFS_DEVICE_BAD_ASHIFT,
			    spa, vd, NULL, NULL, 0, 0);
		}

		vd->vdev_max_asize = max_asize;
	}

	/*
	 * If all children are healthy we update asize if either:
	 * The asize has increased, due to a device expansion caused by dynamic
	 * LUN growth or vdev replacement, and automatic expansion is enabled;
	 * making the additional space available.
	 *
	 * The asize has decreased, due to a device shrink usually caused by a
	 * vdev replace with a smaller device. This ensures that calculations
	 * based of max_asize and asize e.g. esize are always valid. It's safe
	 * to do this as we've already validated that asize is greater than
	 * vdev_min_asize.
	 */
	if (vd->vdev_state == VDEV_STATE_HEALTHY &&
	    ((asize > vd->vdev_asize &&
	    (vd->vdev_expanding || spa->spa_autoexpand)) ||
	    (asize < vd->vdev_asize)))
		vd->vdev_asize = asize;

	vdev_set_min_asize(vd);

	/*
	 * Ensure we can issue some IO before declaring the
	 * vdev open for business.
	 */
	if (vd->vdev_ops->vdev_op_leaf &&
	    (error = zio_wait(vdev_probe(vd, NULL))) != 0) {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_FAULTED,
		    VDEV_AUX_ERR_EXCEEDED);
		return (error);
	}

	/*
	 * Track the min and max ashift values for normal data devices.
	 *
	 * DJB - TBD these should perhaps be tracked per allocation class
	 * (e.g. spa_min_ashift is used to round up post compression buffers)
	 */
	if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
	    vd->vdev_alloc_bias == VDEV_BIAS_NONE &&
	    vd->vdev_aux == NULL) {
		if (vd->vdev_ashift > spa->spa_max_ashift)
			spa->spa_max_ashift = vd->vdev_ashift;
		if (vd->vdev_ashift < spa->spa_min_ashift)
			spa->spa_min_ashift = vd->vdev_ashift;
	}

	/*
	 * If this is a leaf vdev, assess whether a resilver is needed.
	 * But don't do this if we are doing a reopen for a scrub, since
	 * this would just restart the scrub we are already doing.
	 */
	if (vd->vdev_ops->vdev_op_leaf && !spa->spa_scrub_reopen)
		dsl_scan_assess_vdev(spa->spa_dsl_pool, vd);

	return (0);
}

/*
 * Called once the vdevs are all opened, this routine validates the label
 * contents. This needs to be done before vdev_load() so that we don't
 * inadvertently do repair I/Os to the wrong device.
 *
 * This function will only return failure if one of the vdevs indicates that it
 * has since been destroyed or exported.  This is only possible if
 * /etc/zfs/zpool.cache was readonly at the time.  Otherwise, the vdev state
 * will be updated but the function will return 0.
 */
int
vdev_validate(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	nvlist_t *label;
	uint64_t guid = 0, aux_guid = 0, top_guid;
	uint64_t state;
	nvlist_t *nvl;
	uint64_t txg;

	if (vdev_validate_skip)
		return (0);

	for (uint64_t c = 0; c < vd->vdev_children; c++)
		if (vdev_validate(vd->vdev_child[c]) != 0)
			return (SET_ERROR(EBADF));

	/*
	 * If the device has already failed, or was marked offline, don't do
	 * any further validation.  Otherwise, label I/O will fail and we will
	 * overwrite the previous state.
	 */
	if (!vd->vdev_ops->vdev_op_leaf || !vdev_readable(vd))
		return (0);

	/*
	 * If we are performing an extreme rewind, we allow for a label that
	 * was modified at a point after the current txg.
	 * If config lock is not held do not check for the txg. spa_sync could
	 * be updating the vdev's label before updating spa_last_synced_txg.
	 */
	if (spa->spa_extreme_rewind || spa_last_synced_txg(spa) == 0 ||
	    spa_config_held(spa, SCL_CONFIG, RW_WRITER) != SCL_CONFIG)
		txg = UINT64_MAX;
	else
		txg = spa_last_synced_txg(spa);

	if ((label = vdev_label_read_config(vd, txg)) == NULL) {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_BAD_LABEL);
		vdev_dbgmsg(vd, "vdev_validate: failed reading config for "
		    "txg %llu", (u_longlong_t)txg);
		return (0);
	}

	/*
	 * Determine if this vdev has been split off into another
	 * pool.  If so, then refuse to open it.
	 */
	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_SPLIT_GUID,
	    &aux_guid) == 0 && aux_guid == spa_guid(spa)) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_SPLIT_POOL);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: vdev split into other pool");
		return (0);
	}

	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID, &guid) != 0) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
		    ZPOOL_CONFIG_POOL_GUID);
		return (0);
	}

	/*
	 * If config is not trusted then ignore the spa guid check. This is
	 * necessary because if the machine crashed during a re-guid the new
	 * guid might have been written to all of the vdev labels, but not the
	 * cached config. The check will be performed again once we have the
	 * trusted config from the MOS.
	 */
	if (spa->spa_trust_config && guid != spa_guid(spa)) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: vdev label pool_guid doesn't "
		    "match config (%llu != %llu)", (u_longlong_t)guid,
		    (u_longlong_t)spa_guid(spa));
		return (0);
	}

	if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_VDEV_TREE, &nvl)
	    != 0 || nvlist_lookup_uint64(nvl, ZPOOL_CONFIG_ORIG_GUID,
	    &aux_guid) != 0)
		aux_guid = 0;

	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) != 0) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
		    ZPOOL_CONFIG_GUID);
		return (0);
	}

	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_TOP_GUID, &top_guid)
	    != 0) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
		    ZPOOL_CONFIG_TOP_GUID);
		return (0);
	}

	/*
	 * If this vdev just became a top-level vdev because its sibling was
	 * detached, it will have adopted the parent's vdev guid -- but the
	 * label may or may not be on disk yet. Fortunately, either version
	 * of the label will have the same top guid, so if we're a top-level
	 * vdev, we can safely compare to that instead.
	 * However, if the config comes from a cachefile that failed to update
	 * after the detach, a top-level vdev will appear as a non top-level
	 * vdev in the config. Also relax the constraints if we perform an
	 * extreme rewind.
	 *
	 * If we split this vdev off instead, then we also check the
	 * original pool's guid. We don't want to consider the vdev
	 * corrupt if it is partway through a split operation.
	 */
	if (vd->vdev_guid != guid && vd->vdev_guid != aux_guid) {
		boolean_t mismatch = B_FALSE;
		if (spa->spa_trust_config && !spa->spa_extreme_rewind) {
			if (vd != vd->vdev_top || vd->vdev_guid != top_guid)
				mismatch = B_TRUE;
		} else {
			if (vd->vdev_guid != top_guid &&
			    vd->vdev_top->vdev_guid != guid)
				mismatch = B_TRUE;
		}

		if (mismatch) {
			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_CORRUPT_DATA);
			nvlist_free(label);
			vdev_dbgmsg(vd, "vdev_validate: config guid "
			    "doesn't match label guid");
			vdev_dbgmsg(vd, "CONFIG: guid %llu, top_guid %llu",
			    (u_longlong_t)vd->vdev_guid,
			    (u_longlong_t)vd->vdev_top->vdev_guid);
			vdev_dbgmsg(vd, "LABEL: guid %llu, top_guid %llu, "
			    "aux_guid %llu", (u_longlong_t)guid,
			    (u_longlong_t)top_guid, (u_longlong_t)aux_guid);
			return (0);
		}
	}

	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
	    &state) != 0) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
		    ZPOOL_CONFIG_POOL_STATE);
		return (0);
	}

	nvlist_free(label);

	/*
	 * If this is a verbatim import, no need to check the
	 * state of the pool.
	 */
	if (!(spa->spa_import_flags & ZFS_IMPORT_VERBATIM) &&
	    spa_load_state(spa) == SPA_LOAD_OPEN &&
	    state != POOL_STATE_ACTIVE) {
		vdev_dbgmsg(vd, "vdev_validate: invalid pool state (%llu) "
		    "for spa %s", (u_longlong_t)state, spa->spa_name);
		return (SET_ERROR(EBADF));
	}

	/*
	 * If we were able to open and validate a vdev that was
	 * previously marked permanently unavailable, clear that state
	 * now.
	 */
	if (vd->vdev_not_present)
		vd->vdev_not_present = 0;

	return (0);
}

static void
vdev_copy_path_impl(vdev_t *svd, vdev_t *dvd)
{
	if (svd->vdev_path != NULL && dvd->vdev_path != NULL) {
		if (strcmp(svd->vdev_path, dvd->vdev_path) != 0) {
			zfs_dbgmsg("vdev_copy_path: vdev %llu: path changed "
			    "from '%s' to '%s'", (u_longlong_t)dvd->vdev_guid,
			    dvd->vdev_path, svd->vdev_path);
			spa_strfree(dvd->vdev_path);
			dvd->vdev_path = spa_strdup(svd->vdev_path);
		}
	} else if (svd->vdev_path != NULL) {
		dvd->vdev_path = spa_strdup(svd->vdev_path);
		zfs_dbgmsg("vdev_copy_path: vdev %llu: path set to '%s'",
		    (u_longlong_t)dvd->vdev_guid, dvd->vdev_path);
	}
}

/*
 * Recursively copy vdev paths from one vdev to another. Source and destination
 * vdev trees must have same geometry otherwise return error. Intended to copy
 * paths from userland config into MOS config.
 */
int
vdev_copy_path_strict(vdev_t *svd, vdev_t *dvd)
{
	if ((svd->vdev_ops == &vdev_missing_ops) ||
	    (svd->vdev_ishole && dvd->vdev_ishole) ||
	    (dvd->vdev_ops == &vdev_indirect_ops))
		return (0);

	if (svd->vdev_ops != dvd->vdev_ops) {
		vdev_dbgmsg(svd, "vdev_copy_path: vdev type mismatch: %s != %s",
		    svd->vdev_ops->vdev_op_type, dvd->vdev_ops->vdev_op_type);
		return (SET_ERROR(EINVAL));
	}

	if (svd->vdev_guid != dvd->vdev_guid) {
		vdev_dbgmsg(svd, "vdev_copy_path: guids mismatch (%llu != "
		    "%llu)", (u_longlong_t)svd->vdev_guid,
		    (u_longlong_t)dvd->vdev_guid);
		return (SET_ERROR(EINVAL));
	}

	if (svd->vdev_children != dvd->vdev_children) {
		vdev_dbgmsg(svd, "vdev_copy_path: children count mismatch: "
		    "%llu != %llu", (u_longlong_t)svd->vdev_children,
		    (u_longlong_t)dvd->vdev_children);
		return (SET_ERROR(EINVAL));
	}

	for (uint64_t i = 0; i < svd->vdev_children; i++) {
		int error = vdev_copy_path_strict(svd->vdev_child[i],
		    dvd->vdev_child[i]);
		if (error != 0)
			return (error);
	}

	if (svd->vdev_ops->vdev_op_leaf)
		vdev_copy_path_impl(svd, dvd);

	return (0);
}

static void
vdev_copy_path_search(vdev_t *stvd, vdev_t *dvd)
{
	ASSERT(stvd->vdev_top == stvd);
	ASSERT3U(stvd->vdev_id, ==, dvd->vdev_top->vdev_id);

	for (uint64_t i = 0; i < dvd->vdev_children; i++) {
		vdev_copy_path_search(stvd, dvd->vdev_child[i]);
	}

	if (!dvd->vdev_ops->vdev_op_leaf || !vdev_is_concrete(dvd))
		return;

	/*
	 * The idea here is that while a vdev can shift positions within
	 * a top vdev (when replacing, attaching mirror, etc.) it cannot
	 * step outside of it.
	 */
	vdev_t *vd = vdev_lookup_by_guid(stvd, dvd->vdev_guid);

	if (vd == NULL || vd->vdev_ops != dvd->vdev_ops)
		return;

	ASSERT(vd->vdev_ops->vdev_op_leaf);

	vdev_copy_path_impl(vd, dvd);
}

/*
 * Recursively copy vdev paths from one root vdev to another. Source and
 * destination vdev trees may differ in geometry. For each destination leaf
 * vdev, search a vdev with the same guid and top vdev id in the source.
 * Intended to copy paths from userland config into MOS config.
 */
void
vdev_copy_path_relaxed(vdev_t *srvd, vdev_t *drvd)
{
	uint64_t children = MIN(srvd->vdev_children, drvd->vdev_children);
	ASSERT(srvd->vdev_ops == &vdev_root_ops);
	ASSERT(drvd->vdev_ops == &vdev_root_ops);

	for (uint64_t i = 0; i < children; i++) {
		vdev_copy_path_search(srvd->vdev_child[i],
		    drvd->vdev_child[i]);
	}
}

/*
 * Close a virtual device.
 */
void
vdev_close(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	vdev_t *pvd = vd->vdev_parent;

	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);

	/*
	 * If our parent is reopening, then we are as well, unless we are
	 * going offline.
	 */
	if (pvd != NULL && pvd->vdev_reopening)
		vd->vdev_reopening = (pvd->vdev_reopening && !vd->vdev_offline);

	vd->vdev_ops->vdev_op_close(vd);

	vdev_cache_purge(vd);

	/*
	 * We record the previous state before we close it, so that if we are
	 * doing a reopen(), we don't generate FMA ereports if we notice that
	 * it's still faulted.
	 */
	vd->vdev_prevstate = vd->vdev_state;

	if (vd->vdev_offline)
		vd->vdev_state = VDEV_STATE_OFFLINE;
	else
		vd->vdev_state = VDEV_STATE_CLOSED;
	vd->vdev_stat.vs_aux = VDEV_AUX_NONE;
}

void
vdev_hold(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;

	ASSERT(spa_is_root(spa));
	if (spa->spa_state == POOL_STATE_UNINITIALIZED)
		return;

	for (int c = 0; c < vd->vdev_children; c++)
		vdev_hold(vd->vdev_child[c]);

	if (vd->vdev_ops->vdev_op_leaf && vd->vdev_ops->vdev_op_hold != NULL)
		vd->vdev_ops->vdev_op_hold(vd);
}

void
vdev_rele(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;

	ASSERT(spa_is_root(spa));
	for (int c = 0; c < vd->vdev_children; c++)
		vdev_rele(vd->vdev_child[c]);

	if (vd->vdev_ops->vdev_op_leaf && vd->vdev_ops->vdev_op_rele != NULL)
		vd->vdev_ops->vdev_op_rele(vd);
}

/*
 * Reopen all interior vdevs and any unopened leaves.  We don't actually
 * reopen leaf vdevs which had previously been opened as they might deadlock
 * on the spa_config_lock.  Instead we only obtain the leaf's physical size.
 * If the leaf has never been opened then open it, as usual.
 */
void
vdev_reopen(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;

	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);

	/* set the reopening flag unless we're taking the vdev offline */
	vd->vdev_reopening = !vd->vdev_offline;
	vdev_close(vd);
	(void) vdev_open(vd);

	/*
	 * Call vdev_validate() here to make sure we have the same device.
	 * Otherwise, a device with an invalid label could be successfully
	 * opened in response to vdev_reopen().
	 */
	if (vd->vdev_aux) {
		(void) vdev_validate_aux(vd);
		if (vdev_readable(vd) && vdev_writeable(vd) &&
		    vd->vdev_aux == &spa->spa_l2cache) {
			/*
			 * When reopening we can assume the device label has
			 * already the attribute l2cache_persistent, since we've
			 * opened the device in the past and updated the label.
			 * In case the vdev is present we should evict all ARC
			 * buffers and pointers to log blocks and reclaim their
			 * space before restoring its contents to L2ARC.
			 */
			if (l2arc_vdev_present(vd)) {
				l2arc_rebuild_vdev(vd, B_TRUE);
			} else {
				l2arc_add_vdev(spa, vd);
			}
			spa_async_request(spa, SPA_ASYNC_L2CACHE_REBUILD);
		}
	} else {
		(void) vdev_validate(vd);
	}

	/*
	 * Reassess parent vdev's health.
	 */
	vdev_propagate_state(vd);
}

int
vdev_create(vdev_t *vd, uint64_t txg, boolean_t isreplacing)
{
	int error;

	/*
	 * Normally, partial opens (e.g. of a mirror) are allowed.
	 * For a create, however, we want to fail the request if
	 * there are any components we can't open.
	 */
	error = vdev_open(vd);

	if (error || vd->vdev_state != VDEV_STATE_HEALTHY) {
		vdev_close(vd);
		return (error ? error : ENXIO);
	}

	/*
	 * Recursively load DTLs and initialize all labels.
	 */
	if ((error = vdev_dtl_load(vd)) != 0 ||
	    (error = vdev_label_init(vd, txg, isreplacing ?
	    VDEV_LABEL_REPLACE : VDEV_LABEL_CREATE)) != 0) {
		vdev_close(vd);
		return (error);
	}

	return (0);
}

void
vdev_metaslab_set_size(vdev_t *vd)
{
	uint64_t asize = vd->vdev_asize;
	uint64_t ms_count = asize >> zfs_vdev_default_ms_shift;
	uint64_t ms_shift;

	/* BEGIN CSTYLED */
	/*
	 * There are two dimensions to the metaslab sizing calculation:
	 * the size of the metaslab and the count of metaslabs per vdev.
	 *
	 * The default values used below are a good balance between memory
	 * usage (larger metaslab size means more memory needed for loaded
	 * metaslabs; more metaslabs means more memory needed for the
	 * metaslab_t structs), metaslab load time (larger metaslabs take
	 * longer to load), and metaslab sync time (more metaslabs means
	 * more time spent syncing all of them).
	 *
	 * In general, we aim for zfs_vdev_default_ms_count (200) metaslabs.
	 * The range of the dimensions are as follows:
	 *
	 *	2^29 <= ms_size  <= 2^34
	 *	  16 <= ms_count <= 131,072
	 *
	 * On the lower end of vdev sizes, we aim for metaslabs sizes of
	 * at least 512MB (2^29) to minimize fragmentation effects when
	 * testing with smaller devices.  However, the count constraint
	 * of at least 16 metaslabs will override this minimum size goal.
	 *
	 * On the upper end of vdev sizes, we aim for a maximum metaslab
	 * size of 16GB.  However, we will cap the total count to 2^17
	 * metaslabs to keep our memory footprint in check and let the
	 * metaslab size grow from there if that limit is hit.
	 *
	 * The net effect of applying above constrains is summarized below.
	 *
	 *   vdev size	    metaslab count
	 *  --------------|-----------------
	 *	< 8GB		~16
	 *  8GB   - 100GB	one per 512MB
	 *  100GB - 3TB		~200
	 *  3TB   - 2PB		one per 16GB
	 *	> 2PB		~131,072
	 *  --------------------------------
	 *
	 *  Finally, note that all of the above calculate the initial
	 *  number of metaslabs. Expanding a top-level vdev will result
	 *  in additional metaslabs being allocated making it possible
	 *  to exceed the zfs_vdev_ms_count_limit.
	 */
	/* END CSTYLED */

	if (ms_count < zfs_vdev_min_ms_count)
		ms_shift = highbit64(asize / zfs_vdev_min_ms_count);
	else if (ms_count > zfs_vdev_default_ms_count)
		ms_shift = highbit64(asize / zfs_vdev_default_ms_count);
	else
		ms_shift = zfs_vdev_default_ms_shift;

	if (ms_shift < SPA_MAXBLOCKSHIFT) {
		ms_shift = SPA_MAXBLOCKSHIFT;
	} else if (ms_shift > zfs_vdev_max_ms_shift) {
		ms_shift = zfs_vdev_max_ms_shift;
		/* cap the total count to constrain memory footprint */
		if ((asize >> ms_shift) > zfs_vdev_ms_count_limit)
			ms_shift = highbit64(asize / zfs_vdev_ms_count_limit);
	}

	vd->vdev_ms_shift = ms_shift;
	ASSERT3U(vd->vdev_ms_shift, >=, SPA_MAXBLOCKSHIFT);
}

void
vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
{
	ASSERT(vd == vd->vdev_top);
	/* indirect vdevs don't have metaslabs or dtls */
	ASSERT(vdev_is_concrete(vd) || flags == 0);
	ASSERT(ISP2(flags));
	ASSERT(spa_writeable(vd->vdev_spa));

	if (flags & VDD_METASLAB)
		(void) txg_list_add(&vd->vdev_ms_list, arg, txg);

	if (flags & VDD_DTL)
		(void) txg_list_add(&vd->vdev_dtl_list, arg, txg);

	(void) txg_list_add(&vd->vdev_spa->spa_vdev_txg_list, vd, txg);
}

void
vdev_dirty_leaves(vdev_t *vd, int flags, uint64_t txg)
{
	for (int c = 0; c < vd->vdev_children; c++)
		vdev_dirty_leaves(vd->vdev_child[c], flags, txg);

	if (vd->vdev_ops->vdev_op_leaf)
		vdev_dirty(vd->vdev_top, flags, vd, txg);
}

/*
 * DTLs.
 *
 * A vdev's DTL (dirty time log) is the set of transaction groups for which
 * the vdev has less than perfect replication.  There are four kinds of DTL:
 *
 * DTL_MISSING: txgs for which the vdev has no valid copies of the data
 *
 * DTL_PARTIAL: txgs for which data is available, but not fully replicated
 *
 * DTL_SCRUB: the txgs that could not be repaired by the last scrub; upon
 *	scrub completion, DTL_SCRUB replaces DTL_MISSING in the range of
 *	txgs that was scrubbed.
 *
 * DTL_OUTAGE: txgs which cannot currently be read, whether due to
 *	persistent errors or just some device being offline.
 *	Unlike the other three, the DTL_OUTAGE map is not generally
 *	maintained; it's only computed when needed, typically to
 *	determine whether a device can be detached.
 *
 * For leaf vdevs, DTL_MISSING and DTL_PARTIAL are identical: the device
 * either has the data or it doesn't.
 *
 * For interior vdevs such as mirror and RAID-Z the picture is more complex.
 * A vdev's DTL_PARTIAL is the union of its children's DTL_PARTIALs, because
 * if any child is less than fully replicated, then so is its parent.
 * A vdev's DTL_MISSING is a modified union of its children's DTL_MISSINGs,
 * comprising only those txgs which appear in 'maxfaults' or more children;
 * those are the txgs we don't have enough replication to read.  For example,
 * double-parity RAID-Z can tolerate up to two missing devices (maxfaults == 2);
 * thus, its DTL_MISSING consists of the set of txgs that appear in more than
 * two child DTL_MISSING maps.
 *
 * It should be clear from the above that to compute the DTLs and outage maps
 * for all vdevs, it suffices to know just the leaf vdevs' DTL_MISSING maps.
 * Therefore, that is all we keep on disk.  When loading the pool, or after
 * a configuration change, we generate all other DTLs from first principles.
 */
void
vdev_dtl_dirty(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
{
	range_tree_t *rt = vd->vdev_dtl[t];

	ASSERT(t < DTL_TYPES);
	ASSERT(vd != vd->vdev_spa->spa_root_vdev);
	ASSERT(spa_writeable(vd->vdev_spa));

	mutex_enter(&vd->vdev_dtl_lock);
	if (!range_tree_contains(rt, txg, size))
		range_tree_add(rt, txg, size);
	mutex_exit(&vd->vdev_dtl_lock);
}

boolean_t
vdev_dtl_contains(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
{
	range_tree_t *rt = vd->vdev_dtl[t];
	boolean_t dirty = B_FALSE;

	ASSERT(t < DTL_TYPES);
	ASSERT(vd != vd->vdev_spa->spa_root_vdev);

	/*
	 * While we are loading the pool, the DTLs have not been loaded yet.
	 * Ignore the DTLs and try all devices.  This avoids a recursive
	 * mutex enter on the vdev_dtl_lock, and also makes us try hard
	 * when loading the pool (relying on the checksum to ensure that
	 * we get the right data -- note that we while loading, we are
	 * only reading the MOS, which is always checksummed).
	 */
	if (vd->vdev_spa->spa_load_state != SPA_LOAD_NONE)
		return (B_FALSE);

	mutex_enter(&vd->vdev_dtl_lock);
	if (!range_tree_is_empty(rt))
		dirty = range_tree_contains(rt, txg, size);
	mutex_exit(&vd->vdev_dtl_lock);

	return (dirty);
}

boolean_t
vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t t)
{
	range_tree_t *rt = vd->vdev_dtl[t];
	boolean_t empty;

	mutex_enter(&vd->vdev_dtl_lock);
	empty = range_tree_is_empty(rt);
	mutex_exit(&vd->vdev_dtl_lock);

	return (empty);
}

/*
 * Returns B_TRUE if vdev determines offset needs to be resilvered.
 */
boolean_t
vdev_dtl_need_resilver(vdev_t *vd, uint64_t offset, size_t psize)
{
	ASSERT(vd != vd->vdev_spa->spa_root_vdev);

	if (vd->vdev_ops->vdev_op_need_resilver == NULL ||
	    vd->vdev_ops->vdev_op_leaf)
		return (B_TRUE);

	return (vd->vdev_ops->vdev_op_need_resilver(vd, offset, psize));
}

/*
 * Returns the lowest txg in the DTL range.
 */
static uint64_t
vdev_dtl_min(vdev_t *vd)
{
	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
	ASSERT0(vd->vdev_children);

	return (range_tree_min(vd->vdev_dtl[DTL_MISSING]) - 1);
}

/*
 * Returns the highest txg in the DTL.
 */
static uint64_t
vdev_dtl_max(vdev_t *vd)
{
	ASSERT(MUTEX_HELD(&vd->vdev_dtl_lock));
	ASSERT3U(range_tree_space(vd->vdev_dtl[DTL_MISSING]), !=, 0);
	ASSERT0(vd->vdev_children);

	return (range_tree_max(vd->vdev_dtl[DTL_MISSING]));
}

/*
 * Determine if a resilvering vdev should remove any DTL entries from
 * its range. If the vdev was resilvering for the entire duration of the
 * scan then it should excise that range from its DTLs. Otherwise, this
 * vdev is considered partially resilvered and should leave its DTL
 * entries intact. The comment in vdev_dtl_reassess() describes how we
 * excise the DTLs.
 */
static boolean_t
vdev_dtl_should_excise(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;

	ASSERT0(vd->vdev_children);

	if (vd->vdev_state < VDEV_STATE_DEGRADED)
		return (B_FALSE);

	if (vd->vdev_resilver_deferred)
		return (B_FALSE);

	if (vd->vdev_resilver_txg == 0 ||
	    range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]))
		return (B_TRUE);

	/*
	 * When a resilver is initiated the scan will assign the scn_max_txg
	 * value to the highest txg value that exists in all DTLs. If this
	 * device's max DTL is not part of this scan (i.e. it is not in
	 * the range (scn_min_txg, scn_max_txg] then it is not eligible
	 * for excision.
	 */
	if (vdev_dtl_max(vd) <= scn->scn_phys.scn_max_txg) {
		ASSERT3U(scn->scn_phys.scn_min_txg, <=, vdev_dtl_min(vd));
		ASSERT3U(scn->scn_phys.scn_min_txg, <, vd->vdev_resilver_txg);
		ASSERT3U(vd->vdev_resilver_txg, <=, scn->scn_phys.scn_max_txg);
		return (B_TRUE);
	}
	return (B_FALSE);
}

/*
 * Reassess DTLs after a config change or scrub completion.
 */
void
vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
{
	spa_t *spa = vd->vdev_spa;
	avl_tree_t reftree;
	int minref;

	ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);

	for (int c = 0; c < vd->vdev_children; c++)
		vdev_dtl_reassess(vd->vdev_child[c], txg,
		    scrub_txg, scrub_done);

	if (vd == spa->spa_root_vdev || !vdev_is_concrete(vd) || vd->vdev_aux)
		return;

	if (vd->vdev_ops->vdev_op_leaf) {
		dsl_scan_t *scn = spa->spa_dsl_pool->dp_scan;
		boolean_t wasempty = B_TRUE;

		mutex_enter(&vd->vdev_dtl_lock);

		/*
		 * If requested, pretend the scan completed cleanly.
		 */
		if (zfs_scan_ignore_errors && scn)
			scn->scn_phys.scn_errors = 0;

		if (scrub_txg != 0 &&
		    !range_tree_is_empty(vd->vdev_dtl[DTL_MISSING])) {
			wasempty = B_FALSE;
			zfs_dbgmsg("guid:%llu txg:%llu scrub:%llu started:%d "
			    "dtl:%llu/%llu errors:%llu",
			    (u_longlong_t)vd->vdev_guid, (u_longlong_t)txg,
			    (u_longlong_t)scrub_txg, spa->spa_scrub_started,
			    (u_longlong_t)vdev_dtl_min(vd),
			    (u_longlong_t)vdev_dtl_max(vd),
			    (u_longlong_t)(scn ? scn->scn_phys.scn_errors : 0));
		}

		/*
		 * If we've completed a scan cleanly then determine
		 * if this vdev should remove any DTLs. We only want to
		 * excise regions on vdevs that were available during
		 * the entire duration of this scan.
		 */
		if (scrub_txg != 0 &&
		    (spa->spa_scrub_started ||
		    (scn != NULL && scn->scn_phys.scn_errors == 0)) &&
		    vdev_dtl_should_excise(vd)) {
			/*
			 * We completed a scrub up to scrub_txg.  If we
			 * did it without rebooting, then the scrub dtl
			 * will be valid, so excise the old region and
			 * fold in the scrub dtl.  Otherwise, leave the
			 * dtl as-is if there was an error.
			 *
			 * There's little trick here: to excise the beginning
			 * of the DTL_MISSING map, we put it into a reference
			 * tree and then add a segment with refcnt -1 that
			 * covers the range [0, scrub_txg).  This means
			 * that each txg in that range has refcnt -1 or 0.
			 * We then add DTL_SCRUB with a refcnt of 2, so that
			 * entries in the range [0, scrub_txg) will have a
			 * positive refcnt -- either 1 or 2.  We then convert
			 * the reference tree into the new DTL_MISSING map.
			 */
			space_reftree_create(&reftree);
			space_reftree_add_map(&reftree,
			    vd->vdev_dtl[DTL_MISSING], 1);
			space_reftree_add_seg(&reftree, 0, scrub_txg, -1);
			space_reftree_add_map(&reftree,
			    vd->vdev_dtl[DTL_SCRUB], 2);
			space_reftree_generate_map(&reftree,
			    vd->vdev_dtl[DTL_MISSING], 1);
			space_reftree_destroy(&reftree);

			if (!range_tree_is_empty(vd->vdev_dtl[DTL_MISSING])) {
				zfs_dbgmsg("update DTL_MISSING:%llu/%llu",
				    (u_longlong_t)vdev_dtl_min(vd),
				    (u_longlong_t)vdev_dtl_max(vd));
			} else if (!wasempty) {
				zfs_dbgmsg("DTL_MISSING is now empty");
			}
		}
		range_tree_vacate(vd->vdev_dtl[DTL_PARTIAL], NULL, NULL);
		range_tree_walk(vd->vdev_dtl[DTL_MISSING],
		    range_tree_add, vd->vdev_dtl[DTL_PARTIAL]);
		if (scrub_done)
			range_tree_vacate(vd->vdev_dtl[DTL_SCRUB], NULL, NULL);
		range_tree_vacate(vd->vdev_dtl[DTL_OUTAGE], NULL, NULL);
		if (!vdev_readable(vd))
			range_tree_add(vd->vdev_dtl[DTL_OUTAGE], 0, -1ULL);
		else
			range_tree_walk(vd->vdev_dtl[DTL_MISSING],
			    range_tree_add, vd->vdev_dtl[DTL_OUTAGE]);

		/*
		 * If the vdev was resilvering and no longer has any
		 * DTLs then reset its resilvering flag.
		 */
		if (vd->vdev_resilver_txg != 0 &&
		    range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]) &&
		    range_tree_is_empty(vd->vdev_dtl[DTL_OUTAGE]))
			vd->vdev_resilver_txg = 0;

		mutex_exit(&vd->vdev_dtl_lock);

		if (txg != 0)
			vdev_dirty(vd->vdev_top, VDD_DTL, vd, txg);
		return;
	}

	mutex_enter(&vd->vdev_dtl_lock);
	for (int t = 0; t < DTL_TYPES; t++) {
		/* account for child's outage in parent's missing map */
		int s = (t == DTL_MISSING) ? DTL_OUTAGE: t;
		if (t == DTL_SCRUB)
			continue;			/* leaf vdevs only */
		if (t == DTL_PARTIAL)
			minref = 1;			/* i.e. non-zero */
		else if (vd->vdev_nparity != 0)
			minref = vd->vdev_nparity + 1;	/* RAID-Z */
		else
			minref = vd->vdev_children;	/* any kind of mirror */
		space_reftree_create(&reftree);
		for (int c = 0; c < vd->vdev_children; c++) {
			vdev_t *cvd = vd->vdev_child[c];
			mutex_enter(&cvd->vdev_dtl_lock);
			space_reftree_add_map(&reftree, cvd->vdev_dtl[s], 1);
			mutex_exit(&cvd->vdev_dtl_lock);
		}
		space_reftree_generate_map(&reftree, vd->vdev_dtl[t], minref);
		space_reftree_destroy(&reftree);
	}
	mutex_exit(&vd->vdev_dtl_lock);
}

int
vdev_dtl_load(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	objset_t *mos = spa->spa_meta_objset;
	int error = 0;

	if (vd->vdev_ops->vdev_op_leaf && vd->vdev_dtl_object != 0) {
		ASSERT(vdev_is_concrete(vd));

		error = space_map_open(&vd->vdev_dtl_sm, mos,
		    vd->vdev_dtl_object, 0, -1ULL, 0);
		if (error)
			return (error);
		ASSERT(vd->vdev_dtl_sm != NULL);

		mutex_enter(&vd->vdev_dtl_lock);
		error = space_map_load(vd->vdev_dtl_sm,
		    vd->vdev_dtl[DTL_MISSING], SM_ALLOC);
		mutex_exit(&vd->vdev_dtl_lock);

		return (error);
	}

	for (int c = 0; c < vd->vdev_children; c++) {
		error = vdev_dtl_load(vd->vdev_child[c]);
		if (error != 0)
			break;
	}

	return (error);
}

static void
vdev_zap_allocation_data(vdev_t *vd, dmu_tx_t *tx)
{
	spa_t *spa = vd->vdev_spa;
	objset_t *mos = spa->spa_meta_objset;
	vdev_alloc_bias_t alloc_bias = vd->vdev_alloc_bias;
	const char *string;

	ASSERT(alloc_bias != VDEV_BIAS_NONE);

	string =
	    (alloc_bias == VDEV_BIAS_LOG) ? VDEV_ALLOC_BIAS_LOG :
	    (alloc_bias == VDEV_BIAS_SPECIAL) ? VDEV_ALLOC_BIAS_SPECIAL :
	    (alloc_bias == VDEV_BIAS_DEDUP) ? VDEV_ALLOC_BIAS_DEDUP : NULL;

	ASSERT(string != NULL);
	VERIFY0(zap_add(mos, vd->vdev_top_zap, VDEV_TOP_ZAP_ALLOCATION_BIAS,
	    1, strlen(string) + 1, string, tx));

	if (alloc_bias == VDEV_BIAS_SPECIAL || alloc_bias == VDEV_BIAS_DEDUP) {
		spa_activate_allocation_classes(spa, tx);
	}
}

void
vdev_destroy_unlink_zap(vdev_t *vd, uint64_t zapobj, dmu_tx_t *tx)
{
	spa_t *spa = vd->vdev_spa;

	VERIFY0(zap_destroy(spa->spa_meta_objset, zapobj, tx));
	VERIFY0(zap_remove_int(spa->spa_meta_objset, spa->spa_all_vdev_zaps,
	    zapobj, tx));
}

uint64_t
vdev_create_link_zap(vdev_t *vd, dmu_tx_t *tx)
{
	spa_t *spa = vd->vdev_spa;
	uint64_t zap = zap_create(spa->spa_meta_objset, DMU_OTN_ZAP_METADATA,
	    DMU_OT_NONE, 0, tx);

	ASSERT(zap != 0);
	VERIFY0(zap_add_int(spa->spa_meta_objset, spa->spa_all_vdev_zaps,
	    zap, tx));

	return (zap);
}

void
vdev_construct_zaps(vdev_t *vd, dmu_tx_t *tx)
{
	if (vd->vdev_ops != &vdev_hole_ops &&
	    vd->vdev_ops != &vdev_missing_ops &&
	    vd->vdev_ops != &vdev_root_ops &&
	    !vd->vdev_top->vdev_removing) {
		if (vd->vdev_ops->vdev_op_leaf && vd->vdev_leaf_zap == 0) {
			vd->vdev_leaf_zap = vdev_create_link_zap(vd, tx);
		}
		if (vd == vd->vdev_top && vd->vdev_top_zap == 0) {
			vd->vdev_top_zap = vdev_create_link_zap(vd, tx);
			if (vd->vdev_alloc_bias != VDEV_BIAS_NONE)
				vdev_zap_allocation_data(vd, tx);
		}
	}

	for (uint64_t i = 0; i < vd->vdev_children; i++) {
		vdev_construct_zaps(vd->vdev_child[i], tx);
	}
}

void
vdev_dtl_sync(vdev_t *vd, uint64_t txg)
{
	spa_t *spa = vd->vdev_spa;
	range_tree_t *rt = vd->vdev_dtl[DTL_MISSING];
	objset_t *mos = spa->spa_meta_objset;
	range_tree_t *rtsync;
	dmu_tx_t *tx;
	uint64_t object = space_map_object(vd->vdev_dtl_sm);

	ASSERT(vdev_is_concrete(vd));
	ASSERT(vd->vdev_ops->vdev_op_leaf);

	tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);

	if (vd->vdev_detached || vd->vdev_top->vdev_removing) {
		mutex_enter(&vd->vdev_dtl_lock);
		space_map_free(vd->vdev_dtl_sm, tx);
		space_map_close(vd->vdev_dtl_sm);
		vd->vdev_dtl_sm = NULL;
		mutex_exit(&vd->vdev_dtl_lock);

		/*
		 * We only destroy the leaf ZAP for detached leaves or for
		 * removed log devices. Removed data devices handle leaf ZAP
		 * cleanup later, once cancellation is no longer possible.
		 */
		if (vd->vdev_leaf_zap != 0 && (vd->vdev_detached ||
		    vd->vdev_top->vdev_islog)) {
			vdev_destroy_unlink_zap(vd, vd->vdev_leaf_zap, tx);
			vd->vdev_leaf_zap = 0;
		}

		dmu_tx_commit(tx);
		return;
	}

	if (vd->vdev_dtl_sm == NULL) {
		uint64_t new_object;

		new_object = space_map_alloc(mos, zfs_vdev_dtl_sm_blksz, tx);
		VERIFY3U(new_object, !=, 0);

		VERIFY0(space_map_open(&vd->vdev_dtl_sm, mos, new_object,
		    0, -1ULL, 0));
		ASSERT(vd->vdev_dtl_sm != NULL);
	}

	rtsync = range_tree_create(NULL, RANGE_SEG64, NULL, 0, 0);

	mutex_enter(&vd->vdev_dtl_lock);
	range_tree_walk(rt, range_tree_add, rtsync);
	mutex_exit(&vd->vdev_dtl_lock);

	space_map_truncate(vd->vdev_dtl_sm, zfs_vdev_dtl_sm_blksz, tx);
	space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, SM_NO_VDEVID, tx);
	range_tree_vacate(rtsync, NULL, NULL);

	range_tree_destroy(rtsync);

	/*
	 * If the object for the space map has changed then dirty
	 * the top level so that we update the config.
	 */
	if (object != space_map_object(vd->vdev_dtl_sm)) {
		vdev_dbgmsg(vd, "txg %llu, spa %s, DTL old object %llu, "
		    "new object %llu", (u_longlong_t)txg, spa_name(spa),
		    (u_longlong_t)object,
		    (u_longlong_t)space_map_object(vd->vdev_dtl_sm));
		vdev_config_dirty(vd->vdev_top);
	}

	dmu_tx_commit(tx);
}

/*
 * Determine whether the specified vdev can be offlined/detached/removed
 * without losing data.
 */
boolean_t
vdev_dtl_required(vdev_t *vd)
{
	spa_t *spa = vd->vdev_spa;
	vdev_t *tvd = vd->vdev_top;
	uint8_t cant_read = vd->vdev_cant_read;
	boolean_t required;

	ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);

	if (vd == spa->spa_root_vdev || vd == tvd)
		return (B_TRUE);

	/*
	 * Temporarily mark the device as unreadable, and then determine
	 * whether this results in any DTL outages in the top-level vdev.
	 * If not, we can safely offline/detach/remove the device.
	 */
	vd->vdev_cant_read = B_TRUE;
	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);
	required = !vdev_dtl_empty(tvd, DTL_OUTAGE);
	vd->vdev_cant_read = cant_read;
	vdev_dtl_reassess(tvd, 0, 0, B_FALSE);

	if (!required && zio_injection_enabled)
		required = !!zio_handle_device_injection(vd, NULL, ECHILD);

	return (required);
}

/*
 * Determine if resilver is needed, and if so the txg range.
 */
boolean_t
vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
{
	boolean_t needed = B_FALSE;
	uint64_t thismin = UINT64_MAX;
	uint64_t thismax = 0;

	if (vd->vdev_children == 0) {
		mutex_enter(&vd->vdev_dtl_lock);
		if (!range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]) &&
		    vdev_writeable(vd)) {

			thismin = vdev_dtl_min(vd);
			thismax = vdev_dtl_max(vd);
			needed = B_TRUE;
		}
		mutex_exit(&vd->vdev_dtl_lock);
	} else {
		for (int c = 0; c < vd->vdev_children; c++) {
			vdev_t *cvd = vd->vdev_child[c];
			uint64_t cmin, cmax;

			if (vdev_resilver_needed(cvd, &cmin, &cmax)) {
				thismin = MIN(thismin, cmin);
				thismax = MAX(thismax, cmax);
				needed = B_TRUE;
			}
		}
	}

	if (needed && minp) {
		*minp = thismin;
		*maxp = thismax;
	}
	return (needed);
}

/*
 * Gets the checkpoint space map object from the vdev's ZAP.
 * Returns the spacemap object, or 0 if it wasn't in the ZAP
 * or the ZAP doesn't exist yet.
 */
int
vdev_checkpoint_sm_object(vdev_t *vd)
{
	ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
	if (vd->vdev_top_zap == 0) {
		return (0);
	}

	uint64_t sm_obj = 0;
	int err = zap_lookup(spa_meta_objset(vd->vdev_spa), vd->vdev_top_zap,
	    VDEV_TOP_ZAP_POOL_CHECKPOINT_SM, sizeof (uint64_t), 1, &sm_obj);

	ASSERT(err == 0 || err == ENOENT);

	return (sm_obj);
}

int
vdev_load(vdev_t *vd)
{
	int error = 0;
	/*
	 * Recursively load all children.
	 */
	for (int c = 0; c < vd->vdev_children; c++) {
		error = vdev_load(vd->vdev_child[c]);
		if (error != 0) {
			return (error);
		}
	}

	vdev_set_deflate_ratio(vd);

	/*
	 * On spa_load path, grab the allocation bias from our zap
	 */
	if (vd == vd->vdev_top && vd->vdev_top_zap != 0) {
		spa_t *spa = vd->vdev_spa;
		char bias_str[64];

		if (zap_lookup(spa->spa_meta_objset, vd->vdev_top_zap,
		    VDEV_TOP_ZAP_ALLOCATION_BIAS, 1, sizeof (bias_str),
		    bias_str) == 0) {
			ASSERT(vd->vdev_alloc_bias == VDEV_BIAS_NONE);
			vd->vdev_alloc_bias = vdev_derive_alloc_bias(bias_str);
		}
	}

	/*
	 * If this is a top-level vdev, initialize its metaslabs.
	 */
	if (vd == vd->vdev_top && vdev_is_concrete(vd)) {
		vdev_metaslab_group_create(vd);

		if (vd->vdev_ashift == 0 || vd->vdev_asize == 0) {
			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_CORRUPT_DATA);
			vdev_dbgmsg(vd, "vdev_load: invalid size. ashift=%llu, "
			    "asize=%llu", (u_longlong_t)vd->vdev_ashift,
			    (u_longlong_t)vd->vdev_asize);
			return (SET_ERROR(ENXIO));
		}

		error = vdev_metaslab_init(vd, 0);
		if (error != 0) {
			vdev_dbgmsg(vd, "vdev_load: metaslab_init failed "
			    "[error=%d]", error);
			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_CORRUPT_DATA);
			return (error);
		}

		uint64_t checkpoint_sm_obj = vdev_checkpoint_sm_object(vd);
		if (checkpoint_sm_obj != 0) {
			objset_t *mos = spa_meta_objset(vd->vdev_spa);
			ASSERT(vd->vdev_asize != 0);
			ASSERT3P(vd->vdev_checkpoint_sm, ==, NULL);

			error = space_map_open(&vd->vdev_checkpoint_sm,
			    mos, checkpoint_sm_obj, 0, vd->vdev_asize,
			    vd->vdev_ashift);
			if (error != 0) {
				vdev_dbgmsg(vd, "vdev_load: space_map_open "
				    "failed for checkpoint spacemap (obj %llu) "
				    "[error=%d]",
				    (u_longlong_t)checkpoint_sm_obj, error);
				return (error);
			}
			ASSERT3P(vd->vdev_checkpoint_sm, !=, NULL);

			/*
			 * Since the checkpoint_sm contains free entries
			 * exclusively we can use space_map_allocated() to
			 * indicate the cumulative checkpointed space that
			 * has been freed.
			 */
			vd->vdev_stat.vs_checkpoint_space =
			    -space_map_allocated(vd->vdev_checkpoint_sm);
			vd->vdev_spa->spa_checkpoint_info.sci_dspace +=
			    vd->vdev_stat.vs_checkpoint_space;
		}
	}

	/*
	 * If this is a leaf vdev, load its DTL.
	 */
	if (vd->vdev_ops->vdev_op_leaf && (error = vdev_dtl_load(vd)) != 0) {
		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		vdev_dbgmsg(vd, "vdev_load: vdev_dtl_load failed "
		    "[error=%d]", error);
		return (error);
	}

	uint64_t obsolete_sm_object = vdev_obsolete_sm_object(vd);
	if (obsolete_sm_object != 0) {
		objset_t *mos = vd->vdev_spa->spa_meta_objset;
		ASSERT(vd->vdev_asize != 0);
		ASSERT3P(vd->vdev_obsolete_sm, ==, NULL);

		if ((error = space_map_open(&vd->vdev_obsolete_sm, mos,
		    obsolete_sm_object, 0, vd->vdev_asize, 0))) {
			vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
			    VDEV_AUX_CORRUPT_DATA);
			vdev_dbgmsg(vd, "vdev_load: space_map_open failed for "
			    "obsolete spacemap (obj %llu) [error=%d]",
			    (u_longlong_t)obsolete_sm_object, error);
			return (error);
		}
	}

	return (0);
}

/*
 * The special vdev case is used for hot spares and l2cache devices.  Its
 * sole purpose it to set the vdev state for the associated vdev.  To do this,
 * we make sure that we can open the underlying device, then try to read the
 * label, and make sure that the label is sane and that it hasn't been
 * repurposed to another pool.
 */
int
vdev_validate_aux(vdev_t *vd)
{
	nvlist_t *label;
	uint64_t guid, version;
	uint64_t state;

	if (!vdev_readable(vd))
		return (0);

	if ((label = vdev_label_read_config(vd, -1ULL)) == NULL) {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		return (-1);
	}

	if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_VERSION, &version) != 0 ||
	    !SPA_VERSION_IS_SUPPORTED(version) ||
	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) != 0 ||
	    guid != vd->vdev_guid ||
	    nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE, &state) != 0) {
		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
		    VDEV_AUX_CORRUPT_DATA);
		nvlist_free(label);
		return (-1);
	}

	/*
	 * We don't actually check the pool state here.  If it's in fact in
	 * use by another pool, we update this fact on the fly when requested.
	 */
	nvlist_free(label);
	return (0);
}