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[FreeBSD/FreeBSD.git] / sys / cddl / contrib / opensolaris / uts / common / fs / zfs / spa.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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

/*
 * This file contains all the routines used when modifying on-disk SPA state.
 * This includes opening, importing, destroying, exporting a pool, and syncing a
 * pool.
 */

#include <sys/zfs_context.h>
#include <sys/fm/fs/zfs.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/dmu.h>
#include <sys/dmu_tx.h>
#include <sys/zap.h>
#include <sys/zil.h>
#include <sys/vdev_impl.h>
#include <sys/metaslab.h>
#include <sys/uberblock_impl.h>
#include <sys/txg.h>
#include <sys/avl.h>
#include <sys/dmu_traverse.h>
#include <sys/dmu_objset.h>
#include <sys/unique.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_synctask.h>
#include <sys/fs/zfs.h>
#include <sys/callb.h>

int zio_taskq_threads = 0;
SYSCTL_DECL(_vfs_zfs);
SYSCTL_NODE(_vfs_zfs, OID_AUTO, zio, CTLFLAG_RW, 0, "ZFS ZIO");
TUNABLE_INT("vfs.zfs.zio.taskq_threads", &zio_taskq_threads);
SYSCTL_INT(_vfs_zfs_zio, OID_AUTO, taskq_threads, CTLFLAG_RW,
    &zio_taskq_threads, 0, "Number of ZIO threads per ZIO type");


/*
 * ==========================================================================
 * SPA state manipulation (open/create/destroy/import/export)
 * ==========================================================================
 */

static int
spa_error_entry_compare(const void *a, const void *b)
{
        spa_error_entry_t *sa = (spa_error_entry_t *)a;
        spa_error_entry_t *sb = (spa_error_entry_t *)b;
        int ret;

        ret = bcmp(&sa->se_bookmark, &sb->se_bookmark,
            sizeof (zbookmark_t));

        if (ret < 0)
                return (-1);
        else if (ret > 0)
                return (1);
        else
                return (0);
}

/*
 * Utility function which retrieves copies of the current logs and
 * re-initializes them in the process.
 */
void
spa_get_errlists(spa_t *spa, avl_tree_t *last, avl_tree_t *scrub)
{
        ASSERT(MUTEX_HELD(&spa->spa_errlist_lock));

        bcopy(&spa->spa_errlist_last, last, sizeof (avl_tree_t));
        bcopy(&spa->spa_errlist_scrub, scrub, sizeof (avl_tree_t));

        avl_create(&spa->spa_errlist_scrub,
            spa_error_entry_compare, sizeof (spa_error_entry_t),
            offsetof(spa_error_entry_t, se_avl));
        avl_create(&spa->spa_errlist_last,
            spa_error_entry_compare, sizeof (spa_error_entry_t),
            offsetof(spa_error_entry_t, se_avl));
}

/*
 * Activate an uninitialized pool.
 */
static void
spa_activate(spa_t *spa)
{
        int t;
        int nthreads = zio_taskq_threads;
        char name[32];

        ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);

        spa->spa_state = POOL_STATE_ACTIVE;

        spa->spa_normal_class = metaslab_class_create();

        if (nthreads == 0)
                nthreads = max_ncpus;
        for (t = 0; t < ZIO_TYPES; t++) {
                snprintf(name, sizeof(name), "spa_zio_issue %d", t);
                spa->spa_zio_issue_taskq[t] = taskq_create(name, nthreads,
                    maxclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
                snprintf(name, sizeof(name), "spa_zio_intr %d", t);
                spa->spa_zio_intr_taskq[t] = taskq_create(name, nthreads,
                    maxclsyspri, 50, INT_MAX, TASKQ_PREPOPULATE);
        }

        rw_init(&spa->spa_traverse_lock, NULL, RW_DEFAULT, NULL);

        mutex_init(&spa->spa_uberblock_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_errlog_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_errlist_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_config_lock.scl_lock, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&spa->spa_config_lock.scl_cv, NULL, CV_DEFAULT, NULL);
        mutex_init(&spa->spa_sync_bplist.bpl_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_history_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&spa->spa_props_lock, NULL, MUTEX_DEFAULT, NULL);

        list_create(&spa->spa_dirty_list, sizeof (vdev_t),
            offsetof(vdev_t, vdev_dirty_node));

        txg_list_create(&spa->spa_vdev_txg_list,
            offsetof(struct vdev, vdev_txg_node));

        avl_create(&spa->spa_errlist_scrub,
            spa_error_entry_compare, sizeof (spa_error_entry_t),
            offsetof(spa_error_entry_t, se_avl));
        avl_create(&spa->spa_errlist_last,
            spa_error_entry_compare, sizeof (spa_error_entry_t),
            offsetof(spa_error_entry_t, se_avl));
}

/*
 * Opposite of spa_activate().
 */
static void
spa_deactivate(spa_t *spa)
{
        int t;

        ASSERT(spa->spa_sync_on == B_FALSE);
        ASSERT(spa->spa_dsl_pool == NULL);
        ASSERT(spa->spa_root_vdev == NULL);

        ASSERT(spa->spa_state != POOL_STATE_UNINITIALIZED);

        txg_list_destroy(&spa->spa_vdev_txg_list);

        list_destroy(&spa->spa_dirty_list);

        for (t = 0; t < ZIO_TYPES; t++) {
                taskq_destroy(spa->spa_zio_issue_taskq[t]);
                taskq_destroy(spa->spa_zio_intr_taskq[t]);
                spa->spa_zio_issue_taskq[t] = NULL;
                spa->spa_zio_intr_taskq[t] = NULL;
        }

        metaslab_class_destroy(spa->spa_normal_class);
        spa->spa_normal_class = NULL;

        /*
         * If this was part of an import or the open otherwise failed, we may
         * still have errors left in the queues.  Empty them just in case.
         */
        spa_errlog_drain(spa);

        avl_destroy(&spa->spa_errlist_scrub);
        avl_destroy(&spa->spa_errlist_last);

        rw_destroy(&spa->spa_traverse_lock);
        mutex_destroy(&spa->spa_uberblock_lock);
        mutex_destroy(&spa->spa_errlog_lock);
        mutex_destroy(&spa->spa_errlist_lock);
        mutex_destroy(&spa->spa_config_lock.scl_lock);
        cv_destroy(&spa->spa_config_lock.scl_cv);
        mutex_destroy(&spa->spa_sync_bplist.bpl_lock);
        mutex_destroy(&spa->spa_history_lock);
        mutex_destroy(&spa->spa_props_lock);

        spa->spa_state = POOL_STATE_UNINITIALIZED;
}

/*
 * Verify a pool configuration, and construct the vdev tree appropriately.  This
 * will create all the necessary vdevs in the appropriate layout, with each vdev
 * in the CLOSED state.  This will prep the pool before open/creation/import.
 * All vdev validation is done by the vdev_alloc() routine.
 */
static int
spa_config_parse(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent,
    uint_t id, int atype)
{
        nvlist_t **child;
        uint_t c, children;
        int error;

        if ((error = vdev_alloc(spa, vdp, nv, parent, id, atype)) != 0)
                return (error);

        if ((*vdp)->vdev_ops->vdev_op_leaf)
                return (0);

        if (nvlist_lookup_nvlist_array(nv, ZPOOL_CONFIG_CHILDREN,
            &child, &children) != 0) {
                vdev_free(*vdp);
                *vdp = NULL;
                return (EINVAL);
        }

        for (c = 0; c < children; c++) {
                vdev_t *vd;
                if ((error = spa_config_parse(spa, &vd, child[c], *vdp, c,
                    atype)) != 0) {
                        vdev_free(*vdp);
                        *vdp = NULL;
                        return (error);
                }
        }

        ASSERT(*vdp != NULL);

        return (0);
}

/*
 * Opposite of spa_load().
 */
static void
spa_unload(spa_t *spa)
{
        int i;

        /*
         * Stop async tasks.
         */
        spa_async_suspend(spa);

        /*
         * Stop syncing.
         */
        if (spa->spa_sync_on) {
                txg_sync_stop(spa->spa_dsl_pool);
                spa->spa_sync_on = B_FALSE;
        }

        /*
         * Wait for any outstanding prefetch I/O to complete.
         */
        spa_config_enter(spa, RW_WRITER, FTAG);
        spa_config_exit(spa, FTAG);

        /*
         * Close the dsl pool.
         */
        if (spa->spa_dsl_pool) {
                dsl_pool_close(spa->spa_dsl_pool);
                spa->spa_dsl_pool = NULL;
        }

        /*
         * Close all vdevs.
         */
        if (spa->spa_root_vdev)
                vdev_free(spa->spa_root_vdev);
        ASSERT(spa->spa_root_vdev == NULL);

        for (i = 0; i < spa->spa_nspares; i++)
                vdev_free(spa->spa_spares[i]);
        if (spa->spa_spares) {
                kmem_free(spa->spa_spares, spa->spa_nspares * sizeof (void *));
                spa->spa_spares = NULL;
        }
        if (spa->spa_sparelist) {
                nvlist_free(spa->spa_sparelist);
                spa->spa_sparelist = NULL;
        }

        spa->spa_async_suspended = 0;
}

/*
 * Load (or re-load) the current list of vdevs describing the active spares for
 * this pool.  When this is called, we have some form of basic information in
 * 'spa_sparelist'.  We parse this into vdevs, try to open them, and then
 * re-generate a more complete list including status information.
 */
static void
spa_load_spares(spa_t *spa)
{
        nvlist_t **spares;
        uint_t nspares;
        int i;
        vdev_t *vd, *tvd;

        /*
         * First, close and free any existing spare vdevs.
         */
        for (i = 0; i < spa->spa_nspares; i++) {
                vd = spa->spa_spares[i];

                /* Undo the call to spa_activate() below */
                if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid)) != NULL &&
                    tvd->vdev_isspare)
                        spa_spare_remove(tvd);
                vdev_close(vd);
                vdev_free(vd);
        }

        if (spa->spa_spares)
                kmem_free(spa->spa_spares, spa->spa_nspares * sizeof (void *));

        if (spa->spa_sparelist == NULL)
                nspares = 0;
        else
                VERIFY(nvlist_lookup_nvlist_array(spa->spa_sparelist,
                    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);

        spa->spa_nspares = (int)nspares;
        spa->spa_spares = NULL;

        if (nspares == 0)
                return;

        /*
         * Construct the array of vdevs, opening them to get status in the
         * process.   For each spare, there is potentially two different vdev_t
         * structures associated with it: one in the list of spares (used only
         * for basic validation purposes) and one in the active vdev
         * configuration (if it's spared in).  During this phase we open and
         * validate each vdev on the spare list.  If the vdev also exists in the
         * active configuration, then we also mark this vdev as an active spare.
         */
        spa->spa_spares = kmem_alloc(nspares * sizeof (void *), KM_SLEEP);
        for (i = 0; i < spa->spa_nspares; i++) {
                VERIFY(spa_config_parse(spa, &vd, spares[i], NULL, 0,
                    VDEV_ALLOC_SPARE) == 0);
                ASSERT(vd != NULL);

                spa->spa_spares[i] = vd;

                if ((tvd = spa_lookup_by_guid(spa, vd->vdev_guid)) != NULL) {
                        if (!tvd->vdev_isspare)
                                spa_spare_add(tvd);

                        /*
                         * We only mark the spare active if we were successfully
                         * able to load the vdev.  Otherwise, importing a pool
                         * with a bad active spare would result in strange
                         * behavior, because multiple pool would think the spare
                         * is actively in use.
                         *
                         * There is a vulnerability here to an equally bizarre
                         * circumstance, where a dead active spare is later
                         * brought back to life (onlined or otherwise).  Given
                         * the rarity of this scenario, and the extra complexity
                         * it adds, we ignore the possibility.
                         */
                        if (!vdev_is_dead(tvd))
                                spa_spare_activate(tvd);
                }

                if (vdev_open(vd) != 0)
                        continue;

                vd->vdev_top = vd;
                (void) vdev_validate_spare(vd);
        }

        /*
         * Recompute the stashed list of spares, with status information
         * this time.
         */
        VERIFY(nvlist_remove(spa->spa_sparelist, ZPOOL_CONFIG_SPARES,
            DATA_TYPE_NVLIST_ARRAY) == 0);

        spares = kmem_alloc(spa->spa_nspares * sizeof (void *), KM_SLEEP);
        for (i = 0; i < spa->spa_nspares; i++)
                spares[i] = vdev_config_generate(spa, spa->spa_spares[i],
                    B_TRUE, B_TRUE);
        VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist, ZPOOL_CONFIG_SPARES,
            spares, spa->spa_nspares) == 0);
        for (i = 0; i < spa->spa_nspares; i++)
                nvlist_free(spares[i]);
        kmem_free(spares, spa->spa_nspares * sizeof (void *));
}

static int
load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
{
        dmu_buf_t *db;
        char *packed = NULL;
        size_t nvsize = 0;
        int error;
        *value = NULL;

        VERIFY(0 == dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db));
        nvsize = *(uint64_t *)db->db_data;
        dmu_buf_rele(db, FTAG);

        packed = kmem_alloc(nvsize, KM_SLEEP);
        error = dmu_read(spa->spa_meta_objset, obj, 0, nvsize, packed);
        if (error == 0)
                error = nvlist_unpack(packed, nvsize, value, 0);
        kmem_free(packed, nvsize);

        return (error);
}

/*
 * Load an existing storage pool, using the pool's builtin spa_config as a
 * source of configuration information.
 */
static int
spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
{
        int error = 0;
        nvlist_t *nvroot = NULL;
        vdev_t *rvd;
        uberblock_t *ub = &spa->spa_uberblock;
        uint64_t config_cache_txg = spa->spa_config_txg;
        uint64_t pool_guid;
        uint64_t version;
        zio_t *zio;

        spa->spa_load_state = state;

        if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvroot) ||
            nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid)) {
                error = EINVAL;
                goto out;
        }

        /*
         * Versioning wasn't explicitly added to the label until later, so if
         * it's not present treat it as the initial version.
         */
        if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION, &version) != 0)
                version = ZFS_VERSION_INITIAL;

        (void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG,
            &spa->spa_config_txg);

        if ((state == SPA_LOAD_IMPORT || state == SPA_LOAD_TRYIMPORT) &&
            spa_guid_exists(pool_guid, 0)) {
                error = EEXIST;
                goto out;
        }

        spa->spa_load_guid = pool_guid;

        /*
         * Parse the configuration into a vdev tree.  We explicitly set the
         * value that will be returned by spa_version() since parsing the
         * configuration requires knowing the version number.
         */
        spa_config_enter(spa, RW_WRITER, FTAG);
        spa->spa_ubsync.ub_version = version;
        error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, VDEV_ALLOC_LOAD);
        spa_config_exit(spa, FTAG);

        if (error != 0)
                goto out;

        ASSERT(spa->spa_root_vdev == rvd);
        ASSERT(spa_guid(spa) == pool_guid);

        /*
         * Try to open all vdevs, loading each label in the process.
         */
        if (vdev_open(rvd) != 0) {
                error = ENXIO;
                goto out;
        }

        /*
         * Validate the labels for all leaf vdevs.  We need to grab the config
         * lock because all label I/O is done with the ZIO_FLAG_CONFIG_HELD
         * flag.
         */
        spa_config_enter(spa, RW_READER, FTAG);
        error = vdev_validate(rvd);
        spa_config_exit(spa, FTAG);

        if (error != 0) {
                error = EBADF;
                goto out;
        }

        if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
                error = ENXIO;
                goto out;
        }

        /*
         * Find the best uberblock.
         */
        bzero(ub, sizeof (uberblock_t));

        zio = zio_root(spa, NULL, NULL,
            ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
        vdev_uberblock_load(zio, rvd, ub);
        error = zio_wait(zio);

        /*
         * If we weren't able to find a single valid uberblock, return failure.
         */
        if (ub->ub_txg == 0) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = ENXIO;
                goto out;
        }

        /*
         * If the pool is newer than the code, we can't open it.
         */
        if (ub->ub_version > ZFS_VERSION) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_VERSION_NEWER);
                error = ENOTSUP;
                goto out;
        }

        /*
         * If the vdev guid sum doesn't match the uberblock, we have an
         * incomplete configuration.
         */
        if (rvd->vdev_guid_sum != ub->ub_guid_sum && mosconfig) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_BAD_GUID_SUM);
                error = ENXIO;
                goto out;
        }

        /*
         * Initialize internal SPA structures.
         */
        spa->spa_state = POOL_STATE_ACTIVE;
        spa->spa_ubsync = spa->spa_uberblock;
        spa->spa_first_txg = spa_last_synced_txg(spa) + 1;
        error = dsl_pool_open(spa, spa->spa_first_txg, &spa->spa_dsl_pool);
        if (error) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                goto out;
        }
        spa->spa_meta_objset = spa->spa_dsl_pool->dp_meta_objset;

        if (zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CONFIG,
            sizeof (uint64_t), 1, &spa->spa_config_object) != 0) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        if (!mosconfig) {
                nvlist_t *newconfig;
                uint64_t hostid;

                if (load_nvlist(spa, spa->spa_config_object, &newconfig) != 0) {
                        vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                            VDEV_AUX_CORRUPT_DATA);
                        error = EIO;
                        goto out;
                }

                if (nvlist_lookup_uint64(newconfig, ZPOOL_CONFIG_HOSTID,
                    &hostid) == 0) {
                        char *hostname;
                        unsigned long myhostid = 0;

                        VERIFY(nvlist_lookup_string(newconfig,
                            ZPOOL_CONFIG_HOSTNAME, &hostname) == 0);

                        (void) ddi_strtoul(hw_serial, NULL, 10, &myhostid);
                        if ((unsigned long)hostid != myhostid) {
                                cmn_err(CE_WARN, "pool '%s' could not be "
                                    "loaded as it was last accessed by "
                                    "another system (host: %s hostid: 0x%lx).  "
                                    "See: http://www.sun.com/msg/ZFS-8000-EY",
                                    spa->spa_name, hostname,
                                    (unsigned long)hostid);
                                error = EBADF;
                                goto out;
                        }
                }

                spa_config_set(spa, newconfig);
                spa_unload(spa);
                spa_deactivate(spa);
                spa_activate(spa);

                return (spa_load(spa, newconfig, state, B_TRUE));
        }

        if (zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPLIST,
            sizeof (uint64_t), 1, &spa->spa_sync_bplist_obj) != 0) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        /*
         * Load the bit that tells us to use the new accounting function
         * (raid-z deflation).  If we have an older pool, this will not
         * be present.
         */
        error = zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
            sizeof (uint64_t), 1, &spa->spa_deflate);
        if (error != 0 && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        /*
         * Load the persistent error log.  If we have an older pool, this will
         * not be present.
         */
        error = zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_ERRLOG_LAST,
            sizeof (uint64_t), 1, &spa->spa_errlog_last);
        if (error != 0 && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        error = zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_ERRLOG_SCRUB,
            sizeof (uint64_t), 1, &spa->spa_errlog_scrub);
        if (error != 0 && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        /*
         * Load the history object.  If we have an older pool, this
         * will not be present.
         */
        error = zap_lookup(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_HISTORY,
            sizeof (uint64_t), 1, &spa->spa_history);
        if (error != 0 && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        /*
         * Load any hot spares for this pool.
         */
        error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_SPARES, sizeof (uint64_t), 1, &spa->spa_spares_object);
        if (error != 0 && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }
        if (error == 0) {
                ASSERT(spa_version(spa) >= ZFS_VERSION_SPARES);
                if (load_nvlist(spa, spa->spa_spares_object,
                    &spa->spa_sparelist) != 0) {
                        vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                            VDEV_AUX_CORRUPT_DATA);
                        error = EIO;
                        goto out;
                }

                spa_config_enter(spa, RW_WRITER, FTAG);
                spa_load_spares(spa);
                spa_config_exit(spa, FTAG);
        }

        error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
            DMU_POOL_PROPS, sizeof (uint64_t), 1, &spa->spa_pool_props_object);

        if (error && error != ENOENT) {
                vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
                error = EIO;
                goto out;
        }

        if (error == 0) {
                (void) zap_lookup(spa->spa_meta_objset,
                    spa->spa_pool_props_object,
                    zpool_prop_to_name(ZFS_PROP_BOOTFS),
                    sizeof (uint64_t), 1, &spa->spa_bootfs);
        }

        /*
         * Load the vdev state for all toplevel vdevs.
         */
        vdev_load(rvd);

        /*
         * Propagate the leaf DTLs we just loaded all the way up the tree.
         */
        spa_config_enter(spa, RW_WRITER, FTAG);
        vdev_dtl_reassess(rvd, 0, 0, B_FALSE);
        spa_config_exit(spa, FTAG);

        /*
         * Check the state of the root vdev.  If it can't be opened, it
         * indicates one or more toplevel vdevs are faulted.
         */
        if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
                error = ENXIO;
                goto out;
        }

        if ((spa_mode & FWRITE) && state != SPA_LOAD_TRYIMPORT) {
                dmu_tx_t *tx;
                int need_update = B_FALSE;
                int c;

                /*
                 * Claim log blocks that haven't been committed yet.
                 * This must all happen in a single txg.
                 */
                tx = dmu_tx_create_assigned(spa_get_dsl(spa),
                    spa_first_txg(spa));
                (void) dmu_objset_find(spa->spa_name,
                    zil_claim, tx, DS_FIND_CHILDREN);
                dmu_tx_commit(tx);

                spa->spa_sync_on = B_TRUE;
                txg_sync_start(spa->spa_dsl_pool);

                /*
                 * Wait for all claims to sync.
                 */
                txg_wait_synced(spa->spa_dsl_pool, 0);

                /*
                 * If the config cache is stale, or we have uninitialized
                 * metaslabs (see spa_vdev_add()), then update the config.
                 */
                if (config_cache_txg != spa->spa_config_txg ||
                    state == SPA_LOAD_IMPORT)
                        need_update = B_TRUE;

                for (c = 0; c < rvd->vdev_children; c++)
                        if (rvd->vdev_child[c]->vdev_ms_array == 0)
                                need_update = B_TRUE;

                /*
                 * Update the config cache asychronously in case we're the
                 * root pool, in which case the config cache isn't writable yet.
                 */
                if (need_update)
                        spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
        }

        error = 0;
out:
        if (error && error != EBADF)
                zfs_ereport_post(FM_EREPORT_ZFS_POOL, spa, NULL, NULL, 0, 0);
        spa->spa_load_state = SPA_LOAD_NONE;
        spa->spa_ena = 0;

        return (error);
}

/*
 * Pool Open/Import
 *
 * The import case is identical to an open except that the configuration is sent
 * down from userland, instead of grabbed from the configuration cache.  For the
 * case of an open, the pool configuration will exist in the
 * POOL_STATE_UNITIALIZED state.
 *
 * The stats information (gen/count/ustats) is used to gather vdev statistics at
 * the same time open the pool, without having to keep around the spa_t in some
 * ambiguous state.
 */
static int
spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t **config)
{
        spa_t *spa;
        int error;
        int loaded = B_FALSE;
        int locked = B_FALSE;

        *spapp = NULL;

        /*
         * As disgusting as this is, we need to support recursive calls to this
         * function because dsl_dir_open() is called during spa_load(), and ends
         * up calling spa_open() again.  The real fix is to figure out how to
         * avoid dsl_dir_open() calling this in the first place.
         */
        if (mutex_owner(&spa_namespace_lock) != curthread) {
                mutex_enter(&spa_namespace_lock);
                locked = B_TRUE;
        }

        if ((spa = spa_lookup(pool)) == NULL) {
                if (locked)
                        mutex_exit(&spa_namespace_lock);
                return (ENOENT);
        }
        if (spa->spa_state == POOL_STATE_UNINITIALIZED) {

                spa_activate(spa);

                error = spa_load(spa, spa->spa_config, SPA_LOAD_OPEN, B_FALSE);

                if (error == EBADF) {
                        /*
                         * If vdev_validate() returns failure (indicated by
                         * EBADF), it indicates that one of the vdevs indicates
                         * that the pool has been exported or destroyed.  If
                         * this is the case, the config cache is out of sync and
                         * we should remove the pool from the namespace.
                         */
                        zfs_post_ok(spa, NULL);
                        spa_unload(spa);
                        spa_deactivate(spa);
                        spa_remove(spa);
                        spa_config_sync();
                        if (locked)
                                mutex_exit(&spa_namespace_lock);
                        return (ENOENT);
                }

                if (error) {
                        /*
                         * We can't open the pool, but we still have useful
                         * information: the state of each vdev after the
                         * attempted vdev_open().  Return this to the user.
                         */
                        if (config != NULL && spa->spa_root_vdev != NULL) {
                                spa_config_enter(spa, RW_READER, FTAG);
                                *config = spa_config_generate(spa, NULL, -1ULL,
                                    B_TRUE);
                                spa_config_exit(spa, FTAG);
                        }
                        spa_unload(spa);
                        spa_deactivate(spa);
                        spa->spa_last_open_failed = B_TRUE;
                        if (locked)
                                mutex_exit(&spa_namespace_lock);
                        *spapp = NULL;
                        return (error);
                } else {
                        zfs_post_ok(spa, NULL);
                        spa->spa_last_open_failed = B_FALSE;
                }

                loaded = B_TRUE;
        }

        spa_open_ref(spa, tag);
        if (locked)
                mutex_exit(&spa_namespace_lock);

        *spapp = spa;

        if (config != NULL) {
                spa_config_enter(spa, RW_READER, FTAG);
                *config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);
                spa_config_exit(spa, FTAG);
        }

        /*
         * If we just loaded the pool, resilver anything that's out of date.
         */
        if (loaded && (spa_mode & FWRITE))
                VERIFY(spa_scrub(spa, POOL_SCRUB_RESILVER, B_TRUE) == 0);

        return (0);
}

int
spa_open(const char *name, spa_t **spapp, void *tag)
{
        return (spa_open_common(name, spapp, tag, NULL));
}

/*
 * Lookup the given spa_t, incrementing the inject count in the process,
 * preventing it from being exported or destroyed.
 */
spa_t *
spa_inject_addref(char *name)
{
        spa_t *spa;

        mutex_enter(&spa_namespace_lock);
        if ((spa = spa_lookup(name)) == NULL) {
                mutex_exit(&spa_namespace_lock);
                return (NULL);
        }
        spa->spa_inject_ref++;
        mutex_exit(&spa_namespace_lock);

        return (spa);
}

void
spa_inject_delref(spa_t *spa)
{
        mutex_enter(&spa_namespace_lock);
        spa->spa_inject_ref--;
        mutex_exit(&spa_namespace_lock);
}

static void
spa_add_spares(spa_t *spa, nvlist_t *config)
{
        nvlist_t **spares;
        uint_t i, nspares;
        nvlist_t *nvroot;
        uint64_t guid;
        vdev_stat_t *vs;
        uint_t vsc;
        uint64_t pool;

        if (spa->spa_nspares == 0)
                return;

        VERIFY(nvlist_lookup_nvlist(config,
            ZPOOL_CONFIG_VDEV_TREE, &nvroot) == 0);
        VERIFY(nvlist_lookup_nvlist_array(spa->spa_sparelist,
            ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);
        if (nspares != 0) {
                VERIFY(nvlist_add_nvlist_array(nvroot,
                    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                VERIFY(nvlist_lookup_nvlist_array(nvroot,
                    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);

                /*
                 * Go through and find any spares which have since been
                 * repurposed as an active spare.  If this is the case, update
                 * their status appropriately.
                 */
                for (i = 0; i < nspares; i++) {
                        VERIFY(nvlist_lookup_uint64(spares[i],
                            ZPOOL_CONFIG_GUID, &guid) == 0);
                        if (spa_spare_exists(guid, &pool) && pool != 0ULL) {
                                VERIFY(nvlist_lookup_uint64_array(
                                    spares[i], ZPOOL_CONFIG_STATS,
                                    (uint64_t **)&vs, &vsc) == 0);
                                vs->vs_state = VDEV_STATE_CANT_OPEN;
                                vs->vs_aux = VDEV_AUX_SPARED;
                        }
                }
        }
}

int
spa_get_stats(const char *name, nvlist_t **config, char *altroot, size_t buflen)
{
        int error;
        spa_t *spa;

        *config = NULL;
        error = spa_open_common(name, &spa, FTAG, config);

        if (spa && *config != NULL) {
                VERIFY(nvlist_add_uint64(*config, ZPOOL_CONFIG_ERRCOUNT,
                    spa_get_errlog_size(spa)) == 0);

                spa_add_spares(spa, *config);
        }

        /*
         * We want to get the alternate root even for faulted pools, so we cheat
         * and call spa_lookup() directly.
         */
        if (altroot) {
                if (spa == NULL) {
                        mutex_enter(&spa_namespace_lock);
                        spa = spa_lookup(name);
                        if (spa)
                                spa_altroot(spa, altroot, buflen);
                        else
                                altroot[0] = '\0';
                        spa = NULL;
                        mutex_exit(&spa_namespace_lock);
                } else {
                        spa_altroot(spa, altroot, buflen);
                }
        }

        if (spa != NULL)
                spa_close(spa, FTAG);

        return (error);
}

/*
 * Validate that the 'spares' array is well formed.  We must have an array of
 * nvlists, each which describes a valid leaf vdev.  If this is an import (mode
 * is VDEV_ALLOC_SPARE), then we allow corrupted spares to be specified, as long
 * as they are well-formed.
 */
static int
spa_validate_spares(spa_t *spa, nvlist_t *nvroot, uint64_t crtxg, int mode)
{
        nvlist_t **spares;
        uint_t i, nspares;
        vdev_t *vd;
        int error;

        /*
         * It's acceptable to have no spares specified.
         */
        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) != 0)
                return (0);

        if (nspares == 0)
                return (EINVAL);

        /*
         * Make sure the pool is formatted with a version that supports hot
         * spares.
         */
        if (spa_version(spa) < ZFS_VERSION_SPARES)
                return (ENOTSUP);

        /*
         * Set the pending spare list so we correctly handle device in-use
         * checking.
         */
        spa->spa_pending_spares = spares;
        spa->spa_pending_nspares = nspares;

        for (i = 0; i < nspares; i++) {
                if ((error = spa_config_parse(spa, &vd, spares[i], NULL, 0,
                    mode)) != 0)
                        goto out;

                if (!vd->vdev_ops->vdev_op_leaf) {
                        vdev_free(vd);
                        error = EINVAL;
                        goto out;
                }

                vd->vdev_top = vd;

                if ((error = vdev_open(vd)) == 0 &&
                    (error = vdev_label_init(vd, crtxg,
                    VDEV_LABEL_SPARE)) == 0) {
                        VERIFY(nvlist_add_uint64(spares[i], ZPOOL_CONFIG_GUID,
                            vd->vdev_guid) == 0);
                }

                vdev_free(vd);

                if (error && mode != VDEV_ALLOC_SPARE)
                        goto out;
                else
                        error = 0;
        }

out:
        spa->spa_pending_spares = NULL;
        spa->spa_pending_nspares = 0;
        return (error);
}

/*
 * Pool Creation
 */
int
spa_create(const char *pool, nvlist_t *nvroot, const char *altroot)
{
        spa_t *spa;
        vdev_t *rvd;
        dsl_pool_t *dp;
        dmu_tx_t *tx;
        int c, error = 0;
        uint64_t txg = TXG_INITIAL;
        nvlist_t **spares;
        uint_t nspares;

        /*
         * If this pool already exists, return failure.
         */
        mutex_enter(&spa_namespace_lock);
        if (spa_lookup(pool) != NULL) {
                mutex_exit(&spa_namespace_lock);
                return (EEXIST);
        }

        /*
         * Allocate a new spa_t structure.
         */
        spa = spa_add(pool, altroot);
        spa_activate(spa);

        spa->spa_uberblock.ub_txg = txg - 1;
        spa->spa_uberblock.ub_version = ZFS_VERSION;
        spa->spa_ubsync = spa->spa_uberblock;

        /*
         * Create the root vdev.
         */
        spa_config_enter(spa, RW_WRITER, FTAG);

        error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, VDEV_ALLOC_ADD);

        ASSERT(error != 0 || rvd != NULL);
        ASSERT(error != 0 || spa->spa_root_vdev == rvd);

        if (error == 0 && rvd->vdev_children == 0)
                error = EINVAL;

        if (error == 0 &&
            (error = vdev_create(rvd, txg, B_FALSE)) == 0 &&
            (error = spa_validate_spares(spa, nvroot, txg,
            VDEV_ALLOC_ADD)) == 0) {
                for (c = 0; c < rvd->vdev_children; c++)
                        vdev_init(rvd->vdev_child[c], txg);
                vdev_config_dirty(rvd);
        }

        spa_config_exit(spa, FTAG);

        if (error != 0) {
                spa_unload(spa);
                spa_deactivate(spa);
                spa_remove(spa);
                mutex_exit(&spa_namespace_lock);
                return (error);
        }

        /*
         * Get the list of spares, if specified.
         */
        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) == 0) {
                VERIFY(nvlist_alloc(&spa->spa_sparelist, NV_UNIQUE_NAME,
                    KM_SLEEP) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist,
                    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                spa_config_enter(spa, RW_WRITER, FTAG);
                spa_load_spares(spa);
                spa_config_exit(spa, FTAG);
                spa->spa_sync_spares = B_TRUE;
        }

        spa->spa_dsl_pool = dp = dsl_pool_create(spa, txg);
        spa->spa_meta_objset = dp->dp_meta_objset;

        tx = dmu_tx_create_assigned(dp, txg);

        /*
         * Create the pool config object.
         */
        spa->spa_config_object = dmu_object_alloc(spa->spa_meta_objset,
            DMU_OT_PACKED_NVLIST, 1 << 14,
            DMU_OT_PACKED_NVLIST_SIZE, sizeof (uint64_t), tx);

        if (zap_add(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CONFIG,
            sizeof (uint64_t), 1, &spa->spa_config_object, tx) != 0) {
                cmn_err(CE_PANIC, "failed to add pool config");
        }

        /* Newly created pools are always deflated. */
        spa->spa_deflate = TRUE;
        if (zap_add(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
            sizeof (uint64_t), 1, &spa->spa_deflate, tx) != 0) {
                cmn_err(CE_PANIC, "failed to add deflate");
        }

        /*
         * Create the deferred-free bplist object.  Turn off compression
         * because sync-to-convergence takes longer if the blocksize
         * keeps changing.
         */
        spa->spa_sync_bplist_obj = bplist_create(spa->spa_meta_objset,
            1 << 14, tx);
        dmu_object_set_compress(spa->spa_meta_objset, spa->spa_sync_bplist_obj,
            ZIO_COMPRESS_OFF, tx);

        if (zap_add(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPLIST,
            sizeof (uint64_t), 1, &spa->spa_sync_bplist_obj, tx) != 0) {
                cmn_err(CE_PANIC, "failed to add bplist");
        }

        /*
         * Create the pool's history object.
         */
        spa_history_create_obj(spa, tx);

        dmu_tx_commit(tx);

        spa->spa_bootfs = zfs_prop_default_numeric(ZFS_PROP_BOOTFS);
        spa->spa_sync_on = B_TRUE;
        txg_sync_start(spa->spa_dsl_pool);

        /*
         * We explicitly wait for the first transaction to complete so that our
         * bean counters are appropriately updated.
         */
        txg_wait_synced(spa->spa_dsl_pool, txg);

        spa_config_sync();

        mutex_exit(&spa_namespace_lock);

        return (0);
}

/*
 * Import the given pool into the system.  We set up the necessary spa_t and
 * then call spa_load() to do the dirty work.
 */
int
spa_import(const char *pool, nvlist_t *config, const char *altroot)
{
        spa_t *spa;
        int error;
        nvlist_t *nvroot;
        nvlist_t **spares;
        uint_t nspares;

        if (!(spa_mode & FWRITE))
                return (EROFS);

        /*
         * If a pool with this name exists, return failure.
         */
        mutex_enter(&spa_namespace_lock);
        if (spa_lookup(pool) != NULL) {
                mutex_exit(&spa_namespace_lock);
                return (EEXIST);
        }

        /*
         * Create and initialize the spa structure.
         */
        spa = spa_add(pool, altroot);
        spa_activate(spa);

        /*
         * Pass off the heavy lifting to spa_load().
         * Pass TRUE for mosconfig because the user-supplied config
         * is actually the one to trust when doing an import.
         */
        error = spa_load(spa, config, SPA_LOAD_IMPORT, B_TRUE);

        spa_config_enter(spa, RW_WRITER, FTAG);
        /*
         * Toss any existing sparelist, as it doesn't have any validity anymore,
         * and conflicts with spa_has_spare().
         */
        if (spa->spa_sparelist) {
                nvlist_free(spa->spa_sparelist);
                spa->spa_sparelist = NULL;
                spa_load_spares(spa);
        }

        VERIFY(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE,
            &nvroot) == 0);
        if (error == 0)
                error = spa_validate_spares(spa, nvroot, -1ULL,
                    VDEV_ALLOC_SPARE);
        spa_config_exit(spa, FTAG);

        if (error != 0) {
                spa_unload(spa);
                spa_deactivate(spa);
                spa_remove(spa);
                mutex_exit(&spa_namespace_lock);
                return (error);
        }

        /*
         * Override any spares as specified by the user, as these may have
         * correct device names/devids, etc.
         */
        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) == 0) {
                if (spa->spa_sparelist)
                        VERIFY(nvlist_remove(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, DATA_TYPE_NVLIST_ARRAY) == 0);
                else
                        VERIFY(nvlist_alloc(&spa->spa_sparelist,
                            NV_UNIQUE_NAME, KM_SLEEP) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist,
                    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                spa_config_enter(spa, RW_WRITER, FTAG);
                spa_load_spares(spa);
                spa_config_exit(spa, FTAG);
                spa->spa_sync_spares = B_TRUE;
        }

        /*
         * Update the config cache to include the newly-imported pool.
         */
        spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);

        mutex_exit(&spa_namespace_lock);

        /*
         * Resilver anything that's out of date.
         */
        if (spa_mode & FWRITE)
                VERIFY(spa_scrub(spa, POOL_SCRUB_RESILVER, B_TRUE) == 0);

        return (0);
}

/*
 * This (illegal) pool name is used when temporarily importing a spa_t in order
 * to get the vdev stats associated with the imported devices.
 */
#define TRYIMPORT_NAME  "$import"

nvlist_t *
spa_tryimport(nvlist_t *tryconfig)
{
        nvlist_t *config = NULL;
        char *poolname;
        spa_t *spa;
        uint64_t state;

        if (nvlist_lookup_string(tryconfig, ZPOOL_CONFIG_POOL_NAME, &poolname))
                return (NULL);

        if (nvlist_lookup_uint64(tryconfig, ZPOOL_CONFIG_POOL_STATE, &state))
                return (NULL);

        /*
         * Create and initialize the spa structure.
         */
        mutex_enter(&spa_namespace_lock);
        spa = spa_add(TRYIMPORT_NAME, NULL);
        spa_activate(spa);

        /*
         * Pass off the heavy lifting to spa_load().
         * Pass TRUE for mosconfig because the user-supplied config
         * is actually the one to trust when doing an import.
         */
        (void) spa_load(spa, tryconfig, SPA_LOAD_TRYIMPORT, B_TRUE);

        /*
         * If 'tryconfig' was at least parsable, return the current config.
         */
        if (spa->spa_root_vdev != NULL) {
                spa_config_enter(spa, RW_READER, FTAG);
                config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);
                spa_config_exit(spa, FTAG);
                VERIFY(nvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME,
                    poolname) == 0);
                VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE,
                    state) == 0);
                VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_TIMESTAMP,
                    spa->spa_uberblock.ub_timestamp) == 0);

                /*
                 * Add the list of hot spares.
                 */
                spa_add_spares(spa, config);
        }

        spa_unload(spa);
        spa_deactivate(spa);
        spa_remove(spa);
        mutex_exit(&spa_namespace_lock);

        return (config);
}

/*
 * Pool export/destroy
 *
 * The act of destroying or exporting a pool is very simple.  We make sure there
 * is no more pending I/O and any references to the pool are gone.  Then, we
 * update the pool state and sync all the labels to disk, removing the
 * configuration from the cache afterwards.
 */
static int
spa_export_common(char *pool, int new_state, nvlist_t **oldconfig)
{
        spa_t *spa;

        if (oldconfig)
                *oldconfig = NULL;

        if (!(spa_mode & FWRITE))
                return (EROFS);

        mutex_enter(&spa_namespace_lock);
        if ((spa = spa_lookup(pool)) == NULL) {
                mutex_exit(&spa_namespace_lock);
                return (ENOENT);
        }

        /*
         * Put a hold on the pool, drop the namespace lock, stop async tasks,
         * reacquire the namespace lock, and see if we can export.
         */
        spa_open_ref(spa, FTAG);
        mutex_exit(&spa_namespace_lock);
        spa_async_suspend(spa);
        mutex_enter(&spa_namespace_lock);
        spa_close(spa, FTAG);

        /*
         * The pool will be in core if it's openable,
         * in which case we can modify its state.
         */
        if (spa->spa_state != POOL_STATE_UNINITIALIZED && spa->spa_sync_on) {
                /*
                 * Objsets may be open only because they're dirty, so we
                 * have to force it to sync before checking spa_refcnt.
                 */
                spa_scrub_suspend(spa);
                txg_wait_synced(spa->spa_dsl_pool, 0);

                /*
                 * A pool cannot be exported or destroyed if there are active
                 * references.  If we are resetting a pool, allow references by
                 * fault injection handlers.
                 */
                if (!spa_refcount_zero(spa) ||
                    (spa->spa_inject_ref != 0 &&
                    new_state != POOL_STATE_UNINITIALIZED)) {
                        spa_scrub_resume(spa);
                        spa_async_resume(spa);
                        mutex_exit(&spa_namespace_lock);
                        return (EBUSY);
                }

                spa_scrub_resume(spa);
                VERIFY(spa_scrub(spa, POOL_SCRUB_NONE, B_TRUE) == 0);

                /*
                 * We want this to be reflected on every label,
                 * so mark them all dirty.  spa_unload() will do the
                 * final sync that pushes these changes out.
                 */
                if (new_state != POOL_STATE_UNINITIALIZED) {
                        spa_config_enter(spa, RW_WRITER, FTAG);
                        spa->spa_state = new_state;
                        spa->spa_final_txg = spa_last_synced_txg(spa) + 1;
                        vdev_config_dirty(spa->spa_root_vdev);
                        spa_config_exit(spa, FTAG);
                }
        }

        if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
                spa_unload(spa);
                spa_deactivate(spa);
        }

        if (oldconfig && spa->spa_config)
                VERIFY(nvlist_dup(spa->spa_config, oldconfig, 0) == 0);

        if (new_state != POOL_STATE_UNINITIALIZED) {
                spa_remove(spa);
                spa_config_sync();
        }
        mutex_exit(&spa_namespace_lock);

        return (0);
}

/*
 * Destroy a storage pool.
 */
int
spa_destroy(char *pool)
{
        return (spa_export_common(pool, POOL_STATE_DESTROYED, NULL));
}

/*
 * Export a storage pool.
 */
int
spa_export(char *pool, nvlist_t **oldconfig)
{
        return (spa_export_common(pool, POOL_STATE_EXPORTED, oldconfig));
}

/*
 * Similar to spa_export(), this unloads the spa_t without actually removing it
 * from the namespace in any way.
 */
int
spa_reset(char *pool)
{
        return (spa_export_common(pool, POOL_STATE_UNINITIALIZED, NULL));
}


/*
 * ==========================================================================
 * Device manipulation
 * ==========================================================================
 */

/*
 * Add capacity to a storage pool.
 */
int
spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
{
        uint64_t txg;
        int c, error;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *vd, *tvd;
        nvlist_t **spares;
        uint_t i, nspares;

        txg = spa_vdev_enter(spa);

        if ((error = spa_config_parse(spa, &vd, nvroot, NULL, 0,
            VDEV_ALLOC_ADD)) != 0)
                return (spa_vdev_exit(spa, NULL, txg, error));

        spa->spa_pending_vdev = vd;

        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) != 0)
                nspares = 0;

        if (vd->vdev_children == 0 && nspares == 0) {
                spa->spa_pending_vdev = NULL;
                return (spa_vdev_exit(spa, vd, txg, EINVAL));
        }

        if (vd->vdev_children != 0) {
                if ((error = vdev_create(vd, txg, B_FALSE)) != 0) {
                        spa->spa_pending_vdev = NULL;
                        return (spa_vdev_exit(spa, vd, txg, error));
                }
        }

        /*
         * We must validate the spares after checking the children.  Otherwise,
         * vdev_inuse() will blindly overwrite the spare.
         */
        if ((error = spa_validate_spares(spa, nvroot, txg,
            VDEV_ALLOC_ADD)) != 0) {
                spa->spa_pending_vdev = NULL;
                return (spa_vdev_exit(spa, vd, txg, error));
        }

        spa->spa_pending_vdev = NULL;

        /*
         * Transfer each new top-level vdev from vd to rvd.
         */
        for (c = 0; c < vd->vdev_children; c++) {
                tvd = vd->vdev_child[c];
                vdev_remove_child(vd, tvd);
                tvd->vdev_id = rvd->vdev_children;
                vdev_add_child(rvd, tvd);
                vdev_config_dirty(tvd);
        }

        if (nspares != 0) {
                if (spa->spa_sparelist != NULL) {
                        nvlist_t **oldspares;
                        uint_t oldnspares;
                        nvlist_t **newspares;

                        VERIFY(nvlist_lookup_nvlist_array(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, &oldspares, &oldnspares) == 0);

                        newspares = kmem_alloc(sizeof (void *) *
                            (nspares + oldnspares), KM_SLEEP);
                        for (i = 0; i < oldnspares; i++)
                                VERIFY(nvlist_dup(oldspares[i],
                                    &newspares[i], KM_SLEEP) == 0);
                        for (i = 0; i < nspares; i++)
                                VERIFY(nvlist_dup(spares[i],
                                    &newspares[i + oldnspares],
                                    KM_SLEEP) == 0);

                        VERIFY(nvlist_remove(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, DATA_TYPE_NVLIST_ARRAY) == 0);

                        VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, newspares,
                            nspares + oldnspares) == 0);
                        for (i = 0; i < oldnspares + nspares; i++)
                                nvlist_free(newspares[i]);
                        kmem_free(newspares, (oldnspares + nspares) *
                            sizeof (void *));
                } else {
                        VERIFY(nvlist_alloc(&spa->spa_sparelist,
                            NV_UNIQUE_NAME, KM_SLEEP) == 0);
                        VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                }

                spa_load_spares(spa);
                spa->spa_sync_spares = B_TRUE;
        }

        /*
         * We have to be careful when adding new vdevs to an existing pool.
         * If other threads start allocating from these vdevs before we
         * sync the config cache, and we lose power, then upon reboot we may
         * fail to open the pool because there are DVAs that the config cache
         * can't translate.  Therefore, we first add the vdevs without
         * initializing metaslabs; sync the config cache (via spa_vdev_exit());
         * and then let spa_config_update() initialize the new metaslabs.
         *
         * spa_load() checks for added-but-not-initialized vdevs, so that
         * if we lose power at any point in this sequence, the remaining
         * steps will be completed the next time we load the pool.
         */
        (void) spa_vdev_exit(spa, vd, txg, 0);

        mutex_enter(&spa_namespace_lock);
        spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
        mutex_exit(&spa_namespace_lock);

        return (0);
}

/*
 * Attach a device to a mirror.  The arguments are the path to any device
 * in the mirror, and the nvroot for the new device.  If the path specifies
 * a device that is not mirrored, we automatically insert the mirror vdev.
 *
 * If 'replacing' is specified, the new device is intended to replace the
 * existing device; in this case the two devices are made into their own
 * mirror using the 'replacing' vdev, which is functionally idendical to
 * the mirror vdev (it actually reuses all the same ops) but has a few
 * extra rules: you can't attach to it after it's been created, and upon
 * completion of resilvering, the first disk (the one being replaced)
 * is automatically detached.
 */
int
spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
{
        uint64_t txg, open_txg;
        int error;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *oldvd, *newvd, *newrootvd, *pvd, *tvd;
        vdev_ops_t *pvops;

        txg = spa_vdev_enter(spa);

        oldvd = vdev_lookup_by_guid(rvd, guid);

        if (oldvd == NULL)
                return (spa_vdev_exit(spa, NULL, txg, ENODEV));

        if (!oldvd->vdev_ops->vdev_op_leaf)
                return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

        pvd = oldvd->vdev_parent;

        if ((error = spa_config_parse(spa, &newrootvd, nvroot, NULL, 0,
            VDEV_ALLOC_ADD)) != 0 || newrootvd->vdev_children != 1)
                return (spa_vdev_exit(spa, newrootvd, txg, EINVAL));

        newvd = newrootvd->vdev_child[0];

        if (!newvd->vdev_ops->vdev_op_leaf)
                return (spa_vdev_exit(spa, newrootvd, txg, EINVAL));

        if ((error = vdev_create(newrootvd, txg, replacing)) != 0)
                return (spa_vdev_exit(spa, newrootvd, txg, error));

        if (!replacing) {
                /*
                 * For attach, the only allowable parent is a mirror or the root
                 * vdev.
                 */
                if (pvd->vdev_ops != &vdev_mirror_ops &&
                    pvd->vdev_ops != &vdev_root_ops)
                        return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));

                pvops = &vdev_mirror_ops;
        } else {
                /*
                 * Active hot spares can only be replaced by inactive hot
                 * spares.
                 */
                if (pvd->vdev_ops == &vdev_spare_ops &&
                    pvd->vdev_child[1] == oldvd &&
                    !spa_has_spare(spa, newvd->vdev_guid))
                        return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));

                /*
                 * If the source is a hot spare, and the parent isn't already a
                 * spare, then we want to create a new hot spare.  Otherwise, we
                 * want to create a replacing vdev.  The user is not allowed to
                 * attach to a spared vdev child unless the 'isspare' state is
                 * the same (spare replaces spare, non-spare replaces
                 * non-spare).
                 */
                if (pvd->vdev_ops == &vdev_replacing_ops)
                        return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
                else if (pvd->vdev_ops == &vdev_spare_ops &&
                    newvd->vdev_isspare != oldvd->vdev_isspare)
                        return (spa_vdev_exit(spa, newrootvd, txg, ENOTSUP));
                else if (pvd->vdev_ops != &vdev_spare_ops &&
                    newvd->vdev_isspare)
                        pvops = &vdev_spare_ops;
                else
                        pvops = &vdev_replacing_ops;
        }

        /*
         * Compare the new device size with the replaceable/attachable
         * device size.
         */
        if (newvd->vdev_psize < vdev_get_rsize(oldvd))
                return (spa_vdev_exit(spa, newrootvd, txg, EOVERFLOW));

        /*
         * The new device cannot have a higher alignment requirement
         * than the top-level vdev.
         */
        if (newvd->vdev_ashift > oldvd->vdev_top->vdev_ashift)
                return (spa_vdev_exit(spa, newrootvd, txg, EDOM));

        /*
         * If this is an in-place replacement, update oldvd's path and devid
         * to make it distinguishable from newvd, and unopenable from now on.
         */
        if (strcmp(oldvd->vdev_path, newvd->vdev_path) == 0) {
                spa_strfree(oldvd->vdev_path);
                oldvd->vdev_path = kmem_alloc(strlen(newvd->vdev_path) + 5,
                    KM_SLEEP);
                (void) sprintf(oldvd->vdev_path, "%s/%s",
                    newvd->vdev_path, "old");
                if (oldvd->vdev_devid != NULL) {
                        spa_strfree(oldvd->vdev_devid);
                        oldvd->vdev_devid = NULL;
                }
        }

        /*
         * If the parent is not a mirror, or if we're replacing, insert the new
         * mirror/replacing/spare vdev above oldvd.
         */
        if (pvd->vdev_ops != pvops)
                pvd = vdev_add_parent(oldvd, pvops);

        ASSERT(pvd->vdev_top->vdev_parent == rvd);
        ASSERT(pvd->vdev_ops == pvops);
        ASSERT(oldvd->vdev_parent == pvd);

        /*
         * Extract the new device from its root and add it to pvd.
         */
        vdev_remove_child(newrootvd, newvd);
        newvd->vdev_id = pvd->vdev_children;
        vdev_add_child(pvd, newvd);

        /*
         * If newvd is smaller than oldvd, but larger than its rsize,
         * the addition of newvd may have decreased our parent's asize.
         */
        pvd->vdev_asize = MIN(pvd->vdev_asize, newvd->vdev_asize);

        tvd = newvd->vdev_top;
        ASSERT(pvd->vdev_top == tvd);
        ASSERT(tvd->vdev_parent == rvd);

        vdev_config_dirty(tvd);

        /*
         * Set newvd's DTL to [TXG_INITIAL, open_txg].  It will propagate
         * upward when spa_vdev_exit() calls vdev_dtl_reassess().
         */
        open_txg = txg + TXG_CONCURRENT_STATES - 1;

        mutex_enter(&newvd->vdev_dtl_lock);
        space_map_add(&newvd->vdev_dtl_map, TXG_INITIAL,
            open_txg - TXG_INITIAL + 1);
        mutex_exit(&newvd->vdev_dtl_lock);

        if (newvd->vdev_isspare)
                spa_spare_activate(newvd);

        /*
         * Mark newvd's DTL dirty in this txg.
         */
        vdev_dirty(tvd, VDD_DTL, newvd, txg);

        (void) spa_vdev_exit(spa, newrootvd, open_txg, 0);

        /*
         * Kick off a resilver to update newvd.
         */
        VERIFY(spa_scrub(spa, POOL_SCRUB_RESILVER, B_TRUE) == 0);

        return (0);
}

/*
 * Detach a device from a mirror or replacing vdev.
 * If 'replace_done' is specified, only detach if the parent
 * is a replacing vdev.
 */
int
spa_vdev_detach(spa_t *spa, uint64_t guid, int replace_done)
{
        uint64_t txg;
        int c, t, error;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *vd, *pvd, *cvd, *tvd;
        boolean_t unspare = B_FALSE;
        uint64_t unspare_guid;

        txg = spa_vdev_enter(spa);

        vd = vdev_lookup_by_guid(rvd, guid);

        if (vd == NULL)
                return (spa_vdev_exit(spa, NULL, txg, ENODEV));

        if (!vd->vdev_ops->vdev_op_leaf)
                return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

        pvd = vd->vdev_parent;

        /*
         * If replace_done is specified, only remove this device if it's
         * the first child of a replacing vdev.  For the 'spare' vdev, either
         * disk can be removed.
         */
        if (replace_done) {
                if (pvd->vdev_ops == &vdev_replacing_ops) {
                        if (vd->vdev_id != 0)
                                return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));
                } else if (pvd->vdev_ops != &vdev_spare_ops) {
                        return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));
                }
        }

        ASSERT(pvd->vdev_ops != &vdev_spare_ops ||
            spa_version(spa) >= ZFS_VERSION_SPARES);

        /*
         * Only mirror, replacing, and spare vdevs support detach.
         */
        if (pvd->vdev_ops != &vdev_replacing_ops &&
            pvd->vdev_ops != &vdev_mirror_ops &&
            pvd->vdev_ops != &vdev_spare_ops)
                return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

        /*
         * If there's only one replica, you can't detach it.
         */
        if (pvd->vdev_children <= 1)
                return (spa_vdev_exit(spa, NULL, txg, EBUSY));

        /*
         * If all siblings have non-empty DTLs, this device may have the only
         * valid copy of the data, which means we cannot safely detach it.
         *
         * XXX -- as in the vdev_offline() case, we really want a more
         * precise DTL check.
         */
        for (c = 0; c < pvd->vdev_children; c++) {
                uint64_t dirty;

                cvd = pvd->vdev_child[c];
                if (cvd == vd)
                        continue;
                if (vdev_is_dead(cvd))
                        continue;
                mutex_enter(&cvd->vdev_dtl_lock);
                dirty = cvd->vdev_dtl_map.sm_space |
                    cvd->vdev_dtl_scrub.sm_space;
                mutex_exit(&cvd->vdev_dtl_lock);
                if (!dirty)
                        break;
        }

        /*
         * If we are a replacing or spare vdev, then we can always detach the
         * latter child, as that is how one cancels the operation.
         */
        if ((pvd->vdev_ops == &vdev_mirror_ops || vd->vdev_id != 1) &&
            c == pvd->vdev_children)
                return (spa_vdev_exit(spa, NULL, txg, EBUSY));

        /*
         * If we are detaching the original disk from a spare, then it implies
         * that the spare should become a real disk, and be removed from the
         * active spare list for the pool.
         */
        if (pvd->vdev_ops == &vdev_spare_ops &&
            vd->vdev_id == 0)
                unspare = B_TRUE;

        /*
         * Erase the disk labels so the disk can be used for other things.
         * This must be done after all other error cases are handled,
         * but before we disembowel vd (so we can still do I/O to it).
         * But if we can't do it, don't treat the error as fatal --
         * it may be that the unwritability of the disk is the reason
         * it's being detached!
         */
        error = vdev_label_init(vd, 0, VDEV_LABEL_REMOVE);

        /*
         * Remove vd from its parent and compact the parent's children.
         */
        vdev_remove_child(pvd, vd);
        vdev_compact_children(pvd);

        /*
         * Remember one of the remaining children so we can get tvd below.
         */
        cvd = pvd->vdev_child[0];

        /*
         * If we need to remove the remaining child from the list of hot spares,
         * do it now, marking the vdev as no longer a spare in the process.  We
         * must do this before vdev_remove_parent(), because that can change the
         * GUID if it creates a new toplevel GUID.
         */
        if (unspare) {
                ASSERT(cvd->vdev_isspare);
                spa_spare_remove(cvd);
                unspare_guid = cvd->vdev_guid;
        }

        /*
         * If the parent mirror/replacing vdev only has one child,
         * the parent is no longer needed.  Remove it from the tree.
         */
        if (pvd->vdev_children == 1)
                vdev_remove_parent(cvd);

        /*
         * We don't set tvd until now because the parent we just removed
         * may have been the previous top-level vdev.
         */
        tvd = cvd->vdev_top;
        ASSERT(tvd->vdev_parent == rvd);

        /*
         * Reevaluate the parent vdev state.
         */
        vdev_propagate_state(cvd->vdev_parent);

        /*
         * If the device we just detached was smaller than the others, it may be
         * possible to add metaslabs (i.e. grow the pool).  vdev_metaslab_init()
         * can't fail because the existing metaslabs are already in core, so
         * there's nothing to read from disk.
         */
        VERIFY(vdev_metaslab_init(tvd, txg) == 0);

        vdev_config_dirty(tvd);

        /*
         * Mark vd's DTL as dirty in this txg.  vdev_dtl_sync() will see that
         * vd->vdev_detached is set and free vd's DTL object in syncing context.
         * But first make sure we're not on any *other* txg's DTL list, to
         * prevent vd from being accessed after it's freed.
         */
        for (t = 0; t < TXG_SIZE; t++)
                (void) txg_list_remove_this(&tvd->vdev_dtl_list, vd, t);
        vd->vdev_detached = B_TRUE;
        vdev_dirty(tvd, VDD_DTL, vd, txg);

        error = spa_vdev_exit(spa, vd, txg, 0);

        /*
         * If this was the removal of the original device in a hot spare vdev,
         * then we want to go through and remove the device from the hot spare
         * list of every other pool.
         */
        if (unspare) {
                spa = NULL;
                mutex_enter(&spa_namespace_lock);
                while ((spa = spa_next(spa)) != NULL) {
                        if (spa->spa_state != POOL_STATE_ACTIVE)
                                continue;

                        (void) spa_vdev_remove(spa, unspare_guid, B_TRUE);
                }
                mutex_exit(&spa_namespace_lock);
        }

        return (error);
}

/*
 * Remove a device from the pool.  Currently, this supports removing only hot
 * spares.
 */
int
spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
{
        vdev_t *vd;
        nvlist_t **spares, *nv, **newspares;
        uint_t i, j, nspares;
        int ret = 0;

        spa_config_enter(spa, RW_WRITER, FTAG);

        vd = spa_lookup_by_guid(spa, guid);

        nv = NULL;
        if (spa->spa_spares != NULL &&
            nvlist_lookup_nvlist_array(spa->spa_sparelist, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) == 0) {
                for (i = 0; i < nspares; i++) {
                        uint64_t theguid;

                        VERIFY(nvlist_lookup_uint64(spares[i],
                            ZPOOL_CONFIG_GUID, &theguid) == 0);
                        if (theguid == guid) {
                                nv = spares[i];
                                break;
                        }
                }
        }

        /*
         * We only support removing a hot spare, and only if it's not currently
         * in use in this pool.
         */
        if (nv == NULL && vd == NULL) {
                ret = ENOENT;
                goto out;
        }

        if (nv == NULL && vd != NULL) {
                ret = ENOTSUP;
                goto out;
        }

        if (!unspare && nv != NULL && vd != NULL) {
                ret = EBUSY;
                goto out;
        }

        if (nspares == 1) {
                newspares = NULL;
        } else {
                newspares = kmem_alloc((nspares - 1) * sizeof (void *),
                    KM_SLEEP);
                for (i = 0, j = 0; i < nspares; i++) {
                        if (spares[i] != nv)
                                VERIFY(nvlist_dup(spares[i],
                                    &newspares[j++], KM_SLEEP) == 0);
                }
        }

        VERIFY(nvlist_remove(spa->spa_sparelist, ZPOOL_CONFIG_SPARES,
            DATA_TYPE_NVLIST_ARRAY) == 0);
        VERIFY(nvlist_add_nvlist_array(spa->spa_sparelist, ZPOOL_CONFIG_SPARES,
            newspares, nspares - 1) == 0);
        for (i = 0; i < nspares - 1; i++)
                nvlist_free(newspares[i]);
        kmem_free(newspares, (nspares - 1) * sizeof (void *));
        spa_load_spares(spa);
        spa->spa_sync_spares = B_TRUE;

out:
        spa_config_exit(spa, FTAG);

        return (ret);
}

/*
 * Find any device that's done replacing, so we can detach it.
 */
static vdev_t *
spa_vdev_replace_done_hunt(vdev_t *vd)
{
        vdev_t *newvd, *oldvd;
        int c;

        for (c = 0; c < vd->vdev_children; c++) {
                oldvd = spa_vdev_replace_done_hunt(vd->vdev_child[c]);
                if (oldvd != NULL)
                        return (oldvd);
        }

        if (vd->vdev_ops == &vdev_replacing_ops && vd->vdev_children == 2) {
                oldvd = vd->vdev_child[0];
                newvd = vd->vdev_child[1];

                mutex_enter(&newvd->vdev_dtl_lock);
                if (newvd->vdev_dtl_map.sm_space == 0 &&
                    newvd->vdev_dtl_scrub.sm_space == 0) {
                        mutex_exit(&newvd->vdev_dtl_lock);
                        return (oldvd);
                }
                mutex_exit(&newvd->vdev_dtl_lock);
        }

        return (NULL);
}

static void
spa_vdev_replace_done(spa_t *spa)
{
        vdev_t *vd;
        vdev_t *pvd;
        uint64_t guid;
        uint64_t pguid = 0;

        spa_config_enter(spa, RW_READER, FTAG);

        while ((vd = spa_vdev_replace_done_hunt(spa->spa_root_vdev)) != NULL) {
                guid = vd->vdev_guid;
                /*
                 * If we have just finished replacing a hot spared device, then
                 * we need to detach the parent's first child (the original hot
                 * spare) as well.
                 */
                pvd = vd->vdev_parent;
                if (pvd->vdev_parent->vdev_ops == &vdev_spare_ops &&
                    pvd->vdev_id == 0) {
                        ASSERT(pvd->vdev_ops == &vdev_replacing_ops);
                        ASSERT(pvd->vdev_parent->vdev_children == 2);
                        pguid = pvd->vdev_parent->vdev_child[1]->vdev_guid;
                }
                spa_config_exit(spa, FTAG);
                if (spa_vdev_detach(spa, guid, B_TRUE) != 0)
                        return;
                if (pguid != 0 && spa_vdev_detach(spa, pguid, B_TRUE) != 0)
                        return;
                spa_config_enter(spa, RW_READER, FTAG);
        }

        spa_config_exit(spa, FTAG);
}

/*
 * Update the stored path for this vdev.  Dirty the vdev configuration, relying
 * on spa_vdev_enter/exit() to synchronize the labels and cache.
 */
int
spa_vdev_setpath(spa_t *spa, uint64_t guid, const char *newpath)
{
        vdev_t *rvd, *vd;
        uint64_t txg;

        rvd = spa->spa_root_vdev;

        txg = spa_vdev_enter(spa);

        if ((vd = vdev_lookup_by_guid(rvd, guid)) == NULL) {
                /*
                 * Determine if this is a reference to a hot spare.  In that
                 * case, update the path as stored in the spare list.
                 */
                nvlist_t **spares;
                uint_t i, nspares;
                if (spa->spa_sparelist != NULL) {
                        VERIFY(nvlist_lookup_nvlist_array(spa->spa_sparelist,
                            ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0);
                        for (i = 0; i < nspares; i++) {
                                uint64_t theguid;
                                VERIFY(nvlist_lookup_uint64(spares[i],
                                    ZPOOL_CONFIG_GUID, &theguid) == 0);
                                if (theguid == guid)
                                        break;
                        }

                        if (i == nspares)
                                return (spa_vdev_exit(spa, NULL, txg, ENOENT));

                        VERIFY(nvlist_add_string(spares[i],
                            ZPOOL_CONFIG_PATH, newpath) == 0);
                        spa_load_spares(spa);
                        spa->spa_sync_spares = B_TRUE;
                        return (spa_vdev_exit(spa, NULL, txg, 0));
                } else {
                        return (spa_vdev_exit(spa, NULL, txg, ENOENT));
                }
        }

        if (!vd->vdev_ops->vdev_op_leaf)
                return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));

        spa_strfree(vd->vdev_path);
        vd->vdev_path = spa_strdup(newpath);

        vdev_config_dirty(vd->vdev_top);

        return (spa_vdev_exit(spa, NULL, txg, 0));
}

/*
 * ==========================================================================
 * SPA Scrubbing
 * ==========================================================================
 */

static void
spa_scrub_io_done(zio_t *zio)
{
        spa_t *spa = zio->io_spa;

        zio_data_buf_free(zio->io_data, zio->io_size);

        mutex_enter(&spa->spa_scrub_lock);
        if (zio->io_error && !(zio->io_flags & ZIO_FLAG_SPECULATIVE)) {
                vdev_t *vd = zio->io_vd ? zio->io_vd : spa->spa_root_vdev;
                spa->spa_scrub_errors++;
                mutex_enter(&vd->vdev_stat_lock);
                vd->vdev_stat.vs_scrub_errors++;
                mutex_exit(&vd->vdev_stat_lock);
        }

        if (--spa->spa_scrub_inflight < spa->spa_scrub_maxinflight)
                cv_broadcast(&spa->spa_scrub_io_cv);

        ASSERT(spa->spa_scrub_inflight >= 0);

        mutex_exit(&spa->spa_scrub_lock);
}

static void
spa_scrub_io_start(spa_t *spa, blkptr_t *bp, int priority, int flags,
    zbookmark_t *zb)
{
        size_t size = BP_GET_LSIZE(bp);
        void *data;

        mutex_enter(&spa->spa_scrub_lock);
        /*
         * Do not give too much work to vdev(s).
         */
        while (spa->spa_scrub_inflight >= spa->spa_scrub_maxinflight) {
                cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
        }
        spa->spa_scrub_inflight++;
        mutex_exit(&spa->spa_scrub_lock);

        data = zio_data_buf_alloc(size);

        if (zb->zb_level == -1 && BP_GET_TYPE(bp) != DMU_OT_OBJSET)
                flags |= ZIO_FLAG_SPECULATIVE;  /* intent log block */

        flags |= ZIO_FLAG_SCRUB_THREAD | ZIO_FLAG_CANFAIL;

        zio_nowait(zio_read(NULL, spa, bp, data, size,
            spa_scrub_io_done, NULL, priority, flags, zb));
}

/* ARGSUSED */
static int
spa_scrub_cb(traverse_blk_cache_t *bc, spa_t *spa, void *a)
{
        blkptr_t *bp = &bc->bc_blkptr;
        vdev_t *vd = spa->spa_root_vdev;
        dva_t *dva = bp->blk_dva;
        int needs_resilver = B_FALSE;
        int d;

        if (bc->bc_errno) {
                /*
                 * We can't scrub this block, but we can continue to scrub
                 * the rest of the pool.  Note the error and move along.
                 */
                mutex_enter(&spa->spa_scrub_lock);
                spa->spa_scrub_errors++;
                mutex_exit(&spa->spa_scrub_lock);

                mutex_enter(&vd->vdev_stat_lock);
                vd->vdev_stat.vs_scrub_errors++;
                mutex_exit(&vd->vdev_stat_lock);

                return (ERESTART);
        }

        ASSERT(bp->blk_birth < spa->spa_scrub_maxtxg);

        for (d = 0; d < BP_GET_NDVAS(bp); d++) {
                vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dva[d]));

                ASSERT(vd != NULL);

                /*
                 * Keep track of how much data we've examined so that
                 * zpool(1M) status can make useful progress reports.
                 */
                mutex_enter(&vd->vdev_stat_lock);
                vd->vdev_stat.vs_scrub_examined += DVA_GET_ASIZE(&dva[d]);
                mutex_exit(&vd->vdev_stat_lock);

                if (spa->spa_scrub_type == POOL_SCRUB_RESILVER) {
                        if (DVA_GET_GANG(&dva[d])) {
                                /*
                                 * Gang members may be spread across multiple
                                 * vdevs, so the best we can do is look at the
                                 * pool-wide DTL.
                                 * XXX -- it would be better to change our
                                 * allocation policy to ensure that this can't
                                 * happen.
                                 */
                                vd = spa->spa_root_vdev;
                        }
                        if (vdev_dtl_contains(&vd->vdev_dtl_map,
                            bp->blk_birth, 1))
                                needs_resilver = B_TRUE;
                }
        }

        if (spa->spa_scrub_type == POOL_SCRUB_EVERYTHING)
                spa_scrub_io_start(spa, bp, ZIO_PRIORITY_SCRUB,
                    ZIO_FLAG_SCRUB, &bc->bc_bookmark);
        else if (needs_resilver)
                spa_scrub_io_start(spa, bp, ZIO_PRIORITY_RESILVER,
                    ZIO_FLAG_RESILVER, &bc->bc_bookmark);

        return (0);
}

static void
spa_scrub_thread(void *arg)
{
        spa_t *spa = arg;
        callb_cpr_t cprinfo;
        traverse_handle_t *th = spa->spa_scrub_th;
        vdev_t *rvd = spa->spa_root_vdev;
        pool_scrub_type_t scrub_type = spa->spa_scrub_type;
        int error = 0;
        boolean_t complete;

        CALLB_CPR_INIT(&cprinfo, &spa->spa_scrub_lock, callb_generic_cpr, FTAG);

        /*
         * If we're restarting due to a snapshot create/delete,
         * wait for that to complete.
         */
        txg_wait_synced(spa_get_dsl(spa), 0);

        dprintf("start %s mintxg=%llu maxtxg=%llu\n",
            scrub_type == POOL_SCRUB_RESILVER ? "resilver" : "scrub",
            spa->spa_scrub_mintxg, spa->spa_scrub_maxtxg);

        spa_config_enter(spa, RW_WRITER, FTAG);
        vdev_reopen(rvd);               /* purge all vdev caches */
        vdev_config_dirty(rvd);         /* rewrite all disk labels */
        vdev_scrub_stat_update(rvd, scrub_type, B_FALSE);
        spa_config_exit(spa, FTAG);

        mutex_enter(&spa->spa_scrub_lock);
        spa->spa_scrub_errors = 0;
        spa->spa_scrub_active = 1;
        ASSERT(spa->spa_scrub_inflight == 0);

        while (!spa->spa_scrub_stop) {
                CALLB_CPR_SAFE_BEGIN(&cprinfo);
                while (spa->spa_scrub_suspended) {
                        spa->spa_scrub_active = 0;
                        cv_broadcast(&spa->spa_scrub_cv);
                        cv_wait(&spa->spa_scrub_cv, &spa->spa_scrub_lock);
                        spa->spa_scrub_active = 1;
                }
                CALLB_CPR_SAFE_END(&cprinfo, &spa->spa_scrub_lock);

                if (spa->spa_scrub_restart_txg != 0)
                        break;

                mutex_exit(&spa->spa_scrub_lock);
                error = traverse_more(th);
                mutex_enter(&spa->spa_scrub_lock);
                if (error != EAGAIN)
                        break;
        }

        while (spa->spa_scrub_inflight)
                cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);

        spa->spa_scrub_active = 0;
        cv_broadcast(&spa->spa_scrub_cv);

        mutex_exit(&spa->spa_scrub_lock);

        spa_config_enter(spa, RW_WRITER, FTAG);

        mutex_enter(&spa->spa_scrub_lock);

        /*
         * Note: we check spa_scrub_restart_txg under both spa_scrub_lock
         * AND the spa config lock to synchronize with any config changes
         * that revise the DTLs under spa_vdev_enter() / spa_vdev_exit().
         */
        if (spa->spa_scrub_restart_txg != 0)
                error = ERESTART;

        if (spa->spa_scrub_stop)
                error = EINTR;

        /*
         * Even if there were uncorrectable errors, we consider the scrub
         * completed.  The downside is that if there is a transient error during
         * a resilver, we won't resilver the data properly to the target.  But
         * if the damage is permanent (more likely) we will resilver forever,
         * which isn't really acceptable.  Since there is enough information for
         * the user to know what has failed and why, this seems like a more
         * tractable approach.
         */
        complete = (error == 0);

        dprintf("end %s to maxtxg=%llu %s, traverse=%d, %llu errors, stop=%u\n",
            scrub_type == POOL_SCRUB_RESILVER ? "resilver" : "scrub",
            spa->spa_scrub_maxtxg, complete ? "done" : "FAILED",
            error, spa->spa_scrub_errors, spa->spa_scrub_stop);

        mutex_exit(&spa->spa_scrub_lock);

        /*
         * If the scrub/resilver completed, update all DTLs to reflect this.
         * Whether it succeeded or not, vacate all temporary scrub DTLs.
         */
        vdev_dtl_reassess(rvd, spa_last_synced_txg(spa) + 1,
            complete ? spa->spa_scrub_maxtxg : 0, B_TRUE);
        vdev_scrub_stat_update(rvd, POOL_SCRUB_NONE, complete);
        spa_errlog_rotate(spa);

        spa_config_exit(spa, FTAG);

        mutex_enter(&spa->spa_scrub_lock);

        /*
         * We may have finished replacing a device.
         * Let the async thread assess this and handle the detach.
         */
        spa_async_request(spa, SPA_ASYNC_REPLACE_DONE);

        /*
         * If we were told to restart, our final act is to start a new scrub.
         */
        if (error == ERESTART)
                spa_async_request(spa, scrub_type == POOL_SCRUB_RESILVER ?
                    SPA_ASYNC_RESILVER : SPA_ASYNC_SCRUB);

        spa->spa_scrub_type = POOL_SCRUB_NONE;
        spa->spa_scrub_active = 0;
        spa->spa_scrub_thread = NULL;
        cv_broadcast(&spa->spa_scrub_cv);
        CALLB_CPR_EXIT(&cprinfo);       /* drops &spa->spa_scrub_lock */
        thread_exit();
}

void
spa_scrub_suspend(spa_t *spa)
{
        mutex_enter(&spa->spa_scrub_lock);
        spa->spa_scrub_suspended++;
        while (spa->spa_scrub_active) {
                cv_broadcast(&spa->spa_scrub_cv);
                cv_wait(&spa->spa_scrub_cv, &spa->spa_scrub_lock);
        }
        while (spa->spa_scrub_inflight)
                cv_wait(&spa->spa_scrub_io_cv, &spa->spa_scrub_lock);
        mutex_exit(&spa->spa_scrub_lock);
}

void
spa_scrub_resume(spa_t *spa)
{
        mutex_enter(&spa->spa_scrub_lock);
        ASSERT(spa->spa_scrub_suspended != 0);
        if (--spa->spa_scrub_suspended == 0)
                cv_broadcast(&spa->spa_scrub_cv);
        mutex_exit(&spa->spa_scrub_lock);
}

void
spa_scrub_restart(spa_t *spa, uint64_t txg)
{
        /*
         * Something happened (e.g. snapshot create/delete) that means
         * we must restart any in-progress scrubs.  The itinerary will
         * fix this properly.
         */
        mutex_enter(&spa->spa_scrub_lock);
        spa->spa_scrub_restart_txg = txg;
        mutex_exit(&spa->spa_scrub_lock);
}

int
spa_scrub(spa_t *spa, pool_scrub_type_t type, boolean_t force)
{
        space_seg_t *ss;
        uint64_t mintxg, maxtxg;
        vdev_t *rvd = spa->spa_root_vdev;

        if ((uint_t)type >= POOL_SCRUB_TYPES)
                return (ENOTSUP);

        mutex_enter(&spa->spa_scrub_lock);

        /*
         * If there's a scrub or resilver already in progress, stop it.
         */
        while (spa->spa_scrub_thread != NULL) {
                /*
                 * Don't stop a resilver unless forced.
                 */
                if (spa->spa_scrub_type == POOL_SCRUB_RESILVER && !force) {
                        mutex_exit(&spa->spa_scrub_lock);
                        return (EBUSY);
                }
                spa->spa_scrub_stop = 1;
                cv_broadcast(&spa->spa_scrub_cv);
                cv_wait(&spa->spa_scrub_cv, &spa->spa_scrub_lock);
        }

        /*
         * Terminate the previous traverse.
         */
        if (spa->spa_scrub_th != NULL) {
                traverse_fini(spa->spa_scrub_th);
                spa->spa_scrub_th = NULL;
        }

        if (rvd == NULL) {
                ASSERT(spa->spa_scrub_stop == 0);
                ASSERT(spa->spa_scrub_type == type);
                ASSERT(spa->spa_scrub_restart_txg == 0);
                mutex_exit(&spa->spa_scrub_lock);
                return (0);
        }

        mintxg = TXG_INITIAL - 1;
        maxtxg = spa_last_synced_txg(spa) + 1;

        mutex_enter(&rvd->vdev_dtl_lock);

        if (rvd->vdev_dtl_map.sm_space == 0) {
                /*
                 * The pool-wide DTL is empty.
                 * If this is a resilver, there's nothing to do except
                 * check whether any in-progress replacements have completed.
                 */
                if (type == POOL_SCRUB_RESILVER) {
                        type = POOL_SCRUB_NONE;
                        spa_async_request(spa, SPA_ASYNC_REPLACE_DONE);
                }
        } else {
                /*
                 * The pool-wide DTL is non-empty.
                 * If this is a normal scrub, upgrade to a resilver instead.
                 */
                if (type == POOL_SCRUB_EVERYTHING)
                        type = POOL_SCRUB_RESILVER;
        }

        if (type == POOL_SCRUB_RESILVER) {
                /*
                 * Determine the resilvering boundaries.
                 *
                 * Note: (mintxg, maxtxg) is an open interval,
                 * i.e. mintxg and maxtxg themselves are not included.
                 *
                 * Note: for maxtxg, we MIN with spa_last_synced_txg(spa) + 1
                 * so we don't claim to resilver a txg that's still changing.
                 */
                ss = avl_first(&rvd->vdev_dtl_map.sm_root);
                mintxg = ss->ss_start - 1;
                ss = avl_last(&rvd->vdev_dtl_map.sm_root);
                maxtxg = MIN(ss->ss_end, maxtxg);
        }

        mutex_exit(&rvd->vdev_dtl_lock);

        spa->spa_scrub_stop = 0;
        spa->spa_scrub_type = type;
        spa->spa_scrub_restart_txg = 0;

        if (type != POOL_SCRUB_NONE) {
                spa->spa_scrub_mintxg = mintxg;
                spa->spa_scrub_maxtxg = maxtxg;
                spa->spa_scrub_th = traverse_init(spa, spa_scrub_cb, NULL,
                    ADVANCE_PRE | ADVANCE_PRUNE | ADVANCE_ZIL,
                    ZIO_FLAG_CANFAIL);
                traverse_add_pool(spa->spa_scrub_th, mintxg, maxtxg);
                spa->spa_scrub_thread = thread_create(NULL, 0,
                    spa_scrub_thread, spa, 0, &p0, TS_RUN, minclsyspri);
        }

        mutex_exit(&spa->spa_scrub_lock);

        return (0);
}

/*
 * ==========================================================================
 * SPA async task processing
 * ==========================================================================
 */

static void
spa_async_reopen(spa_t *spa)
{
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *tvd;
        int c;

        spa_config_enter(spa, RW_WRITER, FTAG);

        for (c = 0; c < rvd->vdev_children; c++) {
                tvd = rvd->vdev_child[c];
                if (tvd->vdev_reopen_wanted) {
                        tvd->vdev_reopen_wanted = 0;
                        vdev_reopen(tvd);
                }
        }

        spa_config_exit(spa, FTAG);
}

static void
spa_async_thread(void *arg)
{
        spa_t *spa = arg;
        int tasks;

        ASSERT(spa->spa_sync_on);

        mutex_enter(&spa->spa_async_lock);
        tasks = spa->spa_async_tasks;
        spa->spa_async_tasks = 0;
        mutex_exit(&spa->spa_async_lock);

        /*
         * See if the config needs to be updated.
         */
        if (tasks & SPA_ASYNC_CONFIG_UPDATE) {
                mutex_enter(&spa_namespace_lock);
                spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
                mutex_exit(&spa_namespace_lock);
        }

        /*
         * See if any devices need to be reopened.
         */
        if (tasks & SPA_ASYNC_REOPEN)
                spa_async_reopen(spa);

        /*
         * If any devices are done replacing, detach them.
         */
        if (tasks & SPA_ASYNC_REPLACE_DONE)
                spa_vdev_replace_done(spa);

        /*
         * Kick off a scrub.
         */
        if (tasks & SPA_ASYNC_SCRUB)
                VERIFY(spa_scrub(spa, POOL_SCRUB_EVERYTHING, B_TRUE) == 0);

        /*
         * Kick off a resilver.
         */
        if (tasks & SPA_ASYNC_RESILVER)
                VERIFY(spa_scrub(spa, POOL_SCRUB_RESILVER, B_TRUE) == 0);

        /*
         * Let the world know that we're done.
         */
        mutex_enter(&spa->spa_async_lock);
        spa->spa_async_thread = NULL;
        cv_broadcast(&spa->spa_async_cv);
        mutex_exit(&spa->spa_async_lock);
        thread_exit();
}

void
spa_async_suspend(spa_t *spa)
{
        mutex_enter(&spa->spa_async_lock);
        spa->spa_async_suspended++;
        while (spa->spa_async_thread != NULL)
                cv_wait(&spa->spa_async_cv, &spa->spa_async_lock);
        mutex_exit(&spa->spa_async_lock);
}

void
spa_async_resume(spa_t *spa)
{
        mutex_enter(&spa->spa_async_lock);
        ASSERT(spa->spa_async_suspended != 0);
        spa->spa_async_suspended--;
        mutex_exit(&spa->spa_async_lock);
}

static void
spa_async_dispatch(spa_t *spa)
{
        mutex_enter(&spa->spa_async_lock);
        if (spa->spa_async_tasks && !spa->spa_async_suspended &&
            spa->spa_async_thread == NULL &&
            rootdir != NULL && !vn_is_readonly(rootdir))
                spa->spa_async_thread = thread_create(NULL, 0,
                    spa_async_thread, spa, 0, &p0, TS_RUN, maxclsyspri);
        mutex_exit(&spa->spa_async_lock);
}

void
spa_async_request(spa_t *spa, int task)
{
        mutex_enter(&spa->spa_async_lock);
        spa->spa_async_tasks |= task;
        mutex_exit(&spa->spa_async_lock);
}

/*
 * ==========================================================================
 * SPA syncing routines
 * ==========================================================================
 */

static void
spa_sync_deferred_frees(spa_t *spa, uint64_t txg)
{
        bplist_t *bpl = &spa->spa_sync_bplist;
        dmu_tx_t *tx;
        blkptr_t blk;
        uint64_t itor = 0;
        zio_t *zio;
        int error;
        uint8_t c = 1;

        zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CONFIG_HELD);

        while (bplist_iterate(bpl, &itor, &blk) == 0)
                zio_nowait(zio_free(zio, spa, txg, &blk, NULL, NULL));

        error = zio_wait(zio);
        ASSERT3U(error, ==, 0);

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

        /*
         * Pre-dirty the first block so we sync to convergence faster.
         * (Usually only the first block is needed.)
         */
        dmu_write(spa->spa_meta_objset, spa->spa_sync_bplist_obj, 0, 1, &c, tx);
        dmu_tx_commit(tx);
}

static void
spa_sync_nvlist(spa_t *spa, uint64_t obj, nvlist_t *nv, dmu_tx_t *tx)
{
        char *packed = NULL;
        size_t nvsize = 0;
        dmu_buf_t *db;

        VERIFY(nvlist_size(nv, &nvsize, NV_ENCODE_XDR) == 0);

        packed = kmem_alloc(nvsize, KM_SLEEP);

        VERIFY(nvlist_pack(nv, &packed, &nvsize, NV_ENCODE_XDR,
            KM_SLEEP) == 0);

        dmu_write(spa->spa_meta_objset, obj, 0, nvsize, packed, tx);

        kmem_free(packed, nvsize);

        VERIFY(0 == dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db));
        dmu_buf_will_dirty(db, tx);
        *(uint64_t *)db->db_data = nvsize;
        dmu_buf_rele(db, FTAG);
}

static void
spa_sync_spares(spa_t *spa, dmu_tx_t *tx)
{
        nvlist_t *nvroot;
        nvlist_t **spares;
        int i;

        if (!spa->spa_sync_spares)
                return;

        /*
         * Update the MOS nvlist describing the list of available spares.
         * spa_validate_spares() will have already made sure this nvlist is
         * valid and the vdevs are labelled appropriately.
         */
        if (spa->spa_spares_object == 0) {
                spa->spa_spares_object = dmu_object_alloc(spa->spa_meta_objset,
                    DMU_OT_PACKED_NVLIST, 1 << 14,
                    DMU_OT_PACKED_NVLIST_SIZE, sizeof (uint64_t), tx);
                VERIFY(zap_update(spa->spa_meta_objset,
                    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SPARES,
                    sizeof (uint64_t), 1, &spa->spa_spares_object, tx) == 0);
        }

        VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_SLEEP) == 0);
        if (spa->spa_nspares == 0) {
                VERIFY(nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
                    NULL, 0) == 0);
        } else {
                spares = kmem_alloc(spa->spa_nspares * sizeof (void *),
                    KM_SLEEP);
                for (i = 0; i < spa->spa_nspares; i++)
                        spares[i] = vdev_config_generate(spa,
                            spa->spa_spares[i], B_FALSE, B_TRUE);
                VERIFY(nvlist_add_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
                    spares, spa->spa_nspares) == 0);
                for (i = 0; i < spa->spa_nspares; i++)
                        nvlist_free(spares[i]);
                kmem_free(spares, spa->spa_nspares * sizeof (void *));
        }

        spa_sync_nvlist(spa, spa->spa_spares_object, nvroot, tx);
        nvlist_free(nvroot);

        spa->spa_sync_spares = B_FALSE;
}

static void
spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
{
        nvlist_t *config;

        if (list_is_empty(&spa->spa_dirty_list))
                return;

        config = spa_config_generate(spa, NULL, dmu_tx_get_txg(tx), B_FALSE);

        if (spa->spa_config_syncing)
                nvlist_free(spa->spa_config_syncing);
        spa->spa_config_syncing = config;

        spa_sync_nvlist(spa, spa->spa_config_object, config, tx);
}

static void
spa_sync_props(void *arg1, void *arg2, dmu_tx_t *tx)
{
        spa_t *spa = arg1;
        nvlist_t *nvp = arg2;
        nvpair_t *nvpair;
        objset_t *mos = spa->spa_meta_objset;
        uint64_t zapobj;

        mutex_enter(&spa->spa_props_lock);
        if (spa->spa_pool_props_object == 0) {
                zapobj = zap_create(mos, DMU_OT_POOL_PROPS, DMU_OT_NONE, 0, tx);
                VERIFY(zapobj > 0);

                spa->spa_pool_props_object = zapobj;

                VERIFY(zap_update(mos, DMU_POOL_DIRECTORY_OBJECT,
                    DMU_POOL_PROPS, 8, 1,
                    &spa->spa_pool_props_object, tx) == 0);
        }
        mutex_exit(&spa->spa_props_lock);

        nvpair = NULL;
        while ((nvpair = nvlist_next_nvpair(nvp, nvpair))) {
                switch (zpool_name_to_prop(nvpair_name(nvpair))) {
                case ZFS_PROP_BOOTFS:
                        VERIFY(nvlist_lookup_uint64(nvp,
                            nvpair_name(nvpair), &spa->spa_bootfs) == 0);
                        VERIFY(zap_update(mos,
                            spa->spa_pool_props_object,
                            zpool_prop_to_name(ZFS_PROP_BOOTFS), 8, 1,
                            &spa->spa_bootfs, tx) == 0);
                        break;
                }
        }
}

/*
 * Sync the specified transaction group.  New blocks may be dirtied as
 * part of the process, so we iterate until it converges.
 */
void
spa_sync(spa_t *spa, uint64_t txg)
{
        dsl_pool_t *dp = spa->spa_dsl_pool;
        objset_t *mos = spa->spa_meta_objset;
        bplist_t *bpl = &spa->spa_sync_bplist;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *vd;
        dmu_tx_t *tx;
        int dirty_vdevs;

        /*
         * Lock out configuration changes.
         */
        spa_config_enter(spa, RW_READER, FTAG);

        spa->spa_syncing_txg = txg;
        spa->spa_sync_pass = 0;

        VERIFY(0 == bplist_open(bpl, mos, spa->spa_sync_bplist_obj));

        tx = dmu_tx_create_assigned(dp, txg);

        /*
         * If we are upgrading to ZFS_VERSION_RAIDZ_DEFLATE this txg,
         * set spa_deflate if we have no raid-z vdevs.
         */
        if (spa->spa_ubsync.ub_version < ZFS_VERSION_RAIDZ_DEFLATE &&
            spa->spa_uberblock.ub_version >= ZFS_VERSION_RAIDZ_DEFLATE) {
                int i;

                for (i = 0; i < rvd->vdev_children; i++) {
                        vd = rvd->vdev_child[i];
                        if (vd->vdev_deflate_ratio != SPA_MINBLOCKSIZE)
                                break;
                }
                if (i == rvd->vdev_children) {
                        spa->spa_deflate = TRUE;
                        VERIFY(0 == zap_add(spa->spa_meta_objset,
                            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
                            sizeof (uint64_t), 1, &spa->spa_deflate, tx));
                }
        }

        /*
         * If anything has changed in this txg, push the deferred frees
         * from the previous txg.  If not, leave them alone so that we
         * don't generate work on an otherwise idle system.
         */
        if (!txg_list_empty(&dp->dp_dirty_datasets, txg) ||
            !txg_list_empty(&dp->dp_dirty_dirs, txg) ||
            !txg_list_empty(&dp->dp_sync_tasks, txg))
                spa_sync_deferred_frees(spa, txg);

        /*
         * Iterate to convergence.
         */
        do {
                spa->spa_sync_pass++;

                spa_sync_config_object(spa, tx);
                spa_sync_spares(spa, tx);
                spa_errlog_sync(spa, txg);
                dsl_pool_sync(dp, txg);

                dirty_vdevs = 0;
                while (vd = txg_list_remove(&spa->spa_vdev_txg_list, txg)) {
                        vdev_sync(vd, txg);
                        dirty_vdevs++;
                }

                bplist_sync(bpl, tx);
        } while (dirty_vdevs);

        bplist_close(bpl);

        dprintf("txg %llu passes %d\n", txg, spa->spa_sync_pass);

        /*
         * Rewrite the vdev configuration (which includes the uberblock)
         * to commit the transaction group.
         *
         * If there are any dirty vdevs, sync the uberblock to all vdevs.
         * Otherwise, pick a random top-level vdev that's known to be
         * visible in the config cache (see spa_vdev_add() for details).
         * If the write fails, try the next vdev until we're tried them all.
         */
        if (!list_is_empty(&spa->spa_dirty_list)) {
                VERIFY(vdev_config_sync(rvd, txg) == 0);
        } else {
                int children = rvd->vdev_children;
                int c0 = spa_get_random(children);
                int c;

                for (c = 0; c < children; c++) {
                        vd = rvd->vdev_child[(c0 + c) % children];
                        if (vd->vdev_ms_array == 0)
                                continue;
                        if (vdev_config_sync(vd, txg) == 0)
                                break;
                }
                if (c == children)
                        VERIFY(vdev_config_sync(rvd, txg) == 0);
        }

        dmu_tx_commit(tx);

        /*
         * Clear the dirty config list.
         */
        while ((vd = list_head(&spa->spa_dirty_list)) != NULL)
                vdev_config_clean(vd);

        /*
         * Now that the new config has synced transactionally,
         * let it become visible to the config cache.
         */
        if (spa->spa_config_syncing != NULL) {
                spa_config_set(spa, spa->spa_config_syncing);
                spa->spa_config_txg = txg;
                spa->spa_config_syncing = NULL;
        }

        /*
         * Make a stable copy of the fully synced uberblock.
         * We use this as the root for pool traversals.
         */
        spa->spa_traverse_wanted = 1;   /* tells traverse_more() to stop */

        spa_scrub_suspend(spa);         /* stop scrubbing and finish I/Os */

        rw_enter(&spa->spa_traverse_lock, RW_WRITER);
        spa->spa_traverse_wanted = 0;
        spa->spa_ubsync = spa->spa_uberblock;
        rw_exit(&spa->spa_traverse_lock);

        spa_scrub_resume(spa);          /* resume scrub with new ubsync */

        /*
         * Clean up the ZIL records for the synced txg.
         */
        dsl_pool_zil_clean(dp);

        /*
         * Update usable space statistics.
         */
        while (vd = txg_list_remove(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)))
                vdev_sync_done(vd, txg);

        /*
         * It had better be the case that we didn't dirty anything
         * since vdev_config_sync().
         */
        ASSERT(txg_list_empty(&dp->dp_dirty_datasets, txg));
        ASSERT(txg_list_empty(&dp->dp_dirty_dirs, txg));
        ASSERT(txg_list_empty(&spa->spa_vdev_txg_list, txg));
        ASSERT(bpl->bpl_queue == NULL);

        spa_config_exit(spa, FTAG);

        /*
         * If any async tasks have been requested, kick them off.
         */
        spa_async_dispatch(spa);
}

/*
 * Sync all pools.  We don't want to hold the namespace lock across these
 * operations, so we take a reference on the spa_t and drop the lock during the
 * sync.
 */
void
spa_sync_allpools(void)
{
        spa_t *spa = NULL;
        mutex_enter(&spa_namespace_lock);
        while ((spa = spa_next(spa)) != NULL) {
                if (spa_state(spa) != POOL_STATE_ACTIVE)
                        continue;
                spa_open_ref(spa, FTAG);
                mutex_exit(&spa_namespace_lock);
                txg_wait_synced(spa_get_dsl(spa), 0);
                mutex_enter(&spa_namespace_lock);
                spa_close(spa, FTAG);
        }
        mutex_exit(&spa_namespace_lock);
}

/*
 * ==========================================================================
 * Miscellaneous routines
 * ==========================================================================
 */

/*
 * Remove all pools in the system.
 */
void
spa_evict_all(void)
{
        spa_t *spa;

        /*
         * Remove all cached state.  All pools should be closed now,
         * so every spa in the AVL tree should be unreferenced.
         */
        mutex_enter(&spa_namespace_lock);
        while ((spa = spa_next(NULL)) != NULL) {
                /*
                 * Stop async tasks.  The async thread may need to detach
                 * a device that's been replaced, which requires grabbing
                 * spa_namespace_lock, so we must drop it here.
                 */
                spa_open_ref(spa, FTAG);
                mutex_exit(&spa_namespace_lock);
                spa_async_suspend(spa);
                VERIFY(spa_scrub(spa, POOL_SCRUB_NONE, B_TRUE) == 0);
                mutex_enter(&spa_namespace_lock);
                spa_close(spa, FTAG);

                if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
                        spa_unload(spa);
                        spa_deactivate(spa);
                }
                spa_remove(spa);
        }
        mutex_exit(&spa_namespace_lock);
}

vdev_t *
spa_lookup_by_guid(spa_t *spa, uint64_t guid)
{
        return (vdev_lookup_by_guid(spa->spa_root_vdev, guid));
}

void
spa_upgrade(spa_t *spa)
{
        spa_config_enter(spa, RW_WRITER, FTAG);

        /*
         * This should only be called for a non-faulted pool, and since a
         * future version would result in an unopenable pool, this shouldn't be
         * possible.
         */
        ASSERT(spa->spa_uberblock.ub_version <= ZFS_VERSION);

        spa->spa_uberblock.ub_version = ZFS_VERSION;
        vdev_config_dirty(spa->spa_root_vdev);

        spa_config_exit(spa, FTAG);

        txg_wait_synced(spa_get_dsl(spa), 0);
}

boolean_t
spa_has_spare(spa_t *spa, uint64_t guid)
{
        int i;
        uint64_t spareguid;

        for (i = 0; i < spa->spa_nspares; i++)
                if (spa->spa_spares[i]->vdev_guid == guid)
                        return (B_TRUE);

        for (i = 0; i < spa->spa_pending_nspares; i++) {
                if (nvlist_lookup_uint64(spa->spa_pending_spares[i],
                    ZPOOL_CONFIG_GUID, &spareguid) == 0 &&
                    spareguid == guid)
                        return (B_TRUE);
        }

        return (B_FALSE);
}

int
spa_set_props(spa_t *spa, nvlist_t *nvp)
{
        return (dsl_sync_task_do(spa_get_dsl(spa), NULL, spa_sync_props,
            spa, nvp, 3));
}

int
spa_get_props(spa_t *spa, nvlist_t **nvp)
{
        zap_cursor_t zc;
        zap_attribute_t za;
        objset_t *mos = spa->spa_meta_objset;
        zfs_source_t src;
        zfs_prop_t prop;
        nvlist_t *propval;
        uint64_t value;
        int err;

        VERIFY(nvlist_alloc(nvp, NV_UNIQUE_NAME, KM_SLEEP) == 0);

        mutex_enter(&spa->spa_props_lock);
        /* If no props object, then just return empty nvlist */
        if (spa->spa_pool_props_object == 0) {
                mutex_exit(&spa->spa_props_lock);
                return (0);
        }

        for (zap_cursor_init(&zc, mos, spa->spa_pool_props_object);
            (err = zap_cursor_retrieve(&zc, &za)) == 0;
            zap_cursor_advance(&zc)) {

                if ((prop = zpool_name_to_prop(za.za_name)) == ZFS_PROP_INVAL)
                        continue;

                VERIFY(nvlist_alloc(&propval, NV_UNIQUE_NAME, KM_SLEEP) == 0);
                switch (za.za_integer_length) {
                case 8:
                        if (zfs_prop_default_numeric(prop) ==
                            za.za_first_integer)
                                src = ZFS_SRC_DEFAULT;
                        else
                                src = ZFS_SRC_LOCAL;
                        value = za.za_first_integer;

                        if (prop == ZFS_PROP_BOOTFS) {
                                dsl_pool_t *dp;
                                dsl_dataset_t *ds = NULL;
                                char strval[MAXPATHLEN];

                                dp = spa_get_dsl(spa);
                                rw_enter(&dp->dp_config_rwlock, RW_READER);
                                if ((err = dsl_dataset_open_obj(dp,
                                    za.za_first_integer, NULL, DS_MODE_NONE,
                                    FTAG, &ds)) != 0) {
                                        rw_exit(&dp->dp_config_rwlock);
                                        break;
                                }
                                dsl_dataset_name(ds, strval);
                                dsl_dataset_close(ds, DS_MODE_NONE, FTAG);
                                rw_exit(&dp->dp_config_rwlock);

                                VERIFY(nvlist_add_uint64(propval,
                                    ZFS_PROP_SOURCE, src) == 0);
                                VERIFY(nvlist_add_string(propval,
                                    ZFS_PROP_VALUE, strval) == 0);
                        } else {
                                VERIFY(nvlist_add_uint64(propval,
                                    ZFS_PROP_SOURCE, src) == 0);
                                VERIFY(nvlist_add_uint64(propval,
                                    ZFS_PROP_VALUE, value) == 0);
                        }
                        VERIFY(nvlist_add_nvlist(*nvp, za.za_name,
                            propval) == 0);
                        break;
                }
                nvlist_free(propval);
        }
        zap_cursor_fini(&zc);
        mutex_exit(&spa->spa_props_lock);
        if (err && err != ENOENT) {
                nvlist_free(*nvp);
                return (err);
        }

        return (0);
}

/*
 * If the bootfs property value is dsobj, clear it.
 */
void
spa_clear_bootfs(spa_t *spa, uint64_t dsobj, dmu_tx_t *tx)
{
        if (spa->spa_bootfs == dsobj && spa->spa_pool_props_object != 0) {
                VERIFY(zap_remove(spa->spa_meta_objset,
                    spa->spa_pool_props_object,
                    zpool_prop_to_name(ZFS_PROP_BOOTFS), tx) == 0);
                spa->spa_bootfs = 0;
        }
}