--- old/usr/src/uts/common/fs/zfs/spa.c	Mon Aug  5 17:26:53 2019
+++ new/usr/src/uts/common/fs/zfs/spa.c	Mon Aug  5 17:26:53 2019
@@ -21,15 +21,14 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
- * Copyright (c) 2015, Nexenta Systems, Inc.  All rights reserved.
+ * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
+ * Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
  * Copyright 2013 Saso Kiselkov. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
  * Copyright 2016 Toomas Soome <tsoome@me.com>
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2018 Joyent, Inc.
  * Copyright (c) 2017 Datto Inc.
- * Copyright 2018 OmniOS Community Edition (OmniOSce) Association.
  */
 
 /*
@@ -51,15 +50,11 @@
 #include <sys/zil.h>
 #include <sys/ddt.h>
 #include <sys/vdev_impl.h>
-#include <sys/vdev_removal.h>
-#include <sys/vdev_indirect_mapping.h>
-#include <sys/vdev_indirect_births.h>
 #include <sys/metaslab.h>
 #include <sys/metaslab_impl.h>
 #include <sys/uberblock_impl.h>
 #include <sys/txg.h>
 #include <sys/avl.h>
-#include <sys/bpobj.h>
 #include <sys/dmu_traverse.h>
 #include <sys/dmu_objset.h>
 #include <sys/unique.h>
@@ -77,6 +72,9 @@
 #include <sys/dsl_scan.h>
 #include <sys/zfeature.h>
 #include <sys/dsl_destroy.h>
+#include <sys/cos.h>
+#include <sys/special.h>
+#include <sys/wbc.h>
 #include <sys/abd.h>
 
 #ifdef	_KERNEL
@@ -95,7 +93,7 @@
  * The interval, in seconds, at which failed configuration cache file writes
  * should be retried.
  */
-int zfs_ccw_retry_interval = 300;
+static int zfs_ccw_retry_interval = 300;
 
 typedef enum zti_modes {
 	ZTI_MODE_FIXED,			/* value is # of threads (min 1) */
@@ -148,12 +146,22 @@
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* IOCTL */
 };
 
+static sysevent_t *spa_event_create(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl,
+    const char *name);
+static void spa_event_notify_impl(sysevent_t *ev);
 static void spa_sync_version(void *arg, dmu_tx_t *tx);
 static void spa_sync_props(void *arg, dmu_tx_t *tx);
+static void spa_vdev_sync_props(void *arg, dmu_tx_t *tx);
+static int spa_vdev_prop_set_nosync(vdev_t *, nvlist_t *, boolean_t *);
 static boolean_t spa_has_active_shared_spare(spa_t *spa);
-static int spa_load_impl(spa_t *spa, spa_import_type_t type, char **ereport,
-    boolean_t reloading);
+static int spa_load_impl(spa_t *spa, uint64_t, nvlist_t *config,
+    spa_load_state_t state, spa_import_type_t type, boolean_t mosconfig,
+    char **ereport);
 static void spa_vdev_resilver_done(spa_t *spa);
+static void spa_auto_trim(spa_t *spa, uint64_t txg);
+static void spa_vdev_man_trim_done(spa_t *spa);
+static void spa_vdev_auto_trim_done(spa_t *spa);
+static uint64_t spa_min_trim_rate(spa_t *spa);
 
 uint_t		zio_taskq_batch_pct = 75;	/* 1 thread per cpu in pset */
 id_t		zio_taskq_psrset_bind = PS_NONE;
@@ -164,66 +172,6 @@
 extern int	zfs_sync_pass_deferred_free;
 
 /*
- * Report any spa_load_verify errors found, but do not fail spa_load.
- * This is used by zdb to analyze non-idle pools.
- */
-boolean_t	spa_load_verify_dryrun = B_FALSE;
-
-/*
- * 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"
-
-/*
- * For debugging purposes: print out vdev tree during pool import.
- */
-boolean_t	spa_load_print_vdev_tree = B_FALSE;
-
-/*
- * A non-zero value for zfs_max_missing_tvds means that we allow importing
- * pools with missing top-level vdevs. This is strictly intended for advanced
- * pool recovery cases since missing data is almost inevitable. Pools with
- * missing devices can only be imported read-only for safety reasons, and their
- * fail-mode will be automatically set to "continue".
- *
- * With 1 missing vdev we should be able to import the pool and mount all
- * datasets. User data that was not modified after the missing device has been
- * added should be recoverable. This means that snapshots created prior to the
- * addition of that device should be completely intact.
- *
- * With 2 missing vdevs, some datasets may fail to mount since there are
- * dataset statistics that are stored as regular metadata. Some data might be
- * recoverable if those vdevs were added recently.
- *
- * With 3 or more missing vdevs, the pool is severely damaged and MOS entries
- * may be missing entirely. Chances of data recovery are very low. Note that
- * there are also risks of performing an inadvertent rewind as we might be
- * missing all the vdevs with the latest uberblocks.
- */
-uint64_t	zfs_max_missing_tvds = 0;
-
-/*
- * The parameters below are similar to zfs_max_missing_tvds but are only
- * intended for a preliminary open of the pool with an untrusted config which
- * might be incomplete or out-dated.
- *
- * We are more tolerant for pools opened from a cachefile since we could have
- * an out-dated cachefile where a device removal was not registered.
- * We could have set the limit arbitrarily high but in the case where devices
- * are really missing we would want to return the proper error codes; we chose
- * SPA_DVAS_PER_BP - 1 so that some copies of the MOS would still be available
- * and we get a chance to retrieve the trusted config.
- */
-uint64_t	zfs_max_missing_tvds_cachefile = SPA_DVAS_PER_BP - 1;
-/*
- * In the case where config was assembled by scanning device paths (/dev/dsks
- * by default) we are less tolerant since all the existing devices should have
- * been detected and we want spa_load to return the right error codes.
- */
-uint64_t	zfs_max_missing_tvds_scan = 0;
-
-/*
  * ==========================================================================
  * SPA properties routines
  * ==========================================================================
@@ -259,6 +207,7 @@
 {
 	vdev_t *rvd = spa->spa_root_vdev;
 	dsl_pool_t *pool = spa->spa_dsl_pool;
+	spa_meta_placement_t *mp = &spa->spa_meta_policy;
 	uint64_t size, alloc, cap, version;
 	zprop_source_t src = ZPROP_SRC_NONE;
 	spa_config_dirent_t *dp;
@@ -274,7 +223,28 @@
 		spa_prop_add_list(*nvp, ZPOOL_PROP_ALLOCATED, NULL, alloc, src);
 		spa_prop_add_list(*nvp, ZPOOL_PROP_FREE, NULL,
 		    size - alloc, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_ENABLESPECIAL, NULL,
+		    (uint64_t)spa->spa_usesc, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_MINWATERMARK, NULL,
+		    spa->spa_minwat, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_HIWATERMARK, NULL,
+		    spa->spa_hiwat, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_LOWATERMARK, NULL,
+		    spa->spa_lowat, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUPMETA_DITTO, NULL,
+		    spa->spa_ddt_meta_copies, src);
 
+		spa_prop_add_list(*nvp, ZPOOL_PROP_META_PLACEMENT, NULL,
+		    mp->spa_enable_meta_placement_selection, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_SYNC_TO_SPECIAL, NULL,
+		    mp->spa_sync_to_special, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DDT_META_TO_METADEV, NULL,
+		    mp->spa_ddt_meta_to_special, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_ZFS_META_TO_METADEV,
+		    NULL, mp->spa_zfs_meta_to_special, src);
+		spa_prop_add_list(*nvp, ZPOOL_PROP_SMALL_DATA_TO_METADEV, NULL,
+		    mp->spa_small_data_to_special, src);
+
 		spa_prop_add_list(*nvp, ZPOOL_PROP_FRAGMENTATION, NULL,
 		    metaslab_class_fragmentation(mc), src);
 		spa_prop_add_list(*nvp, ZPOOL_PROP_EXPANDSZ, NULL,
@@ -282,12 +252,27 @@
 		spa_prop_add_list(*nvp, ZPOOL_PROP_READONLY, NULL,
 		    (spa_mode(spa) == FREAD), src);
 
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DDT_DESEGREGATION, NULL,
+		    (spa->spa_ddt_class_min == spa->spa_ddt_class_max), src);
+
 		cap = (size == 0) ? 0 : (alloc * 100 / size);
 		spa_prop_add_list(*nvp, ZPOOL_PROP_CAPACITY, NULL, cap, src);
 
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUP_BEST_EFFORT, NULL,
+		    spa->spa_dedup_best_effort, src);
+
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUP_LO_BEST_EFFORT, NULL,
+		    spa->spa_dedup_lo_best_effort, src);
+
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUP_HI_BEST_EFFORT, NULL,
+		    spa->spa_dedup_hi_best_effort, src);
+
 		spa_prop_add_list(*nvp, ZPOOL_PROP_DEDUPRATIO, NULL,
 		    ddt_get_pool_dedup_ratio(spa), src);
 
+		spa_prop_add_list(*nvp, ZPOOL_PROP_DDTCAPPED, NULL,
+		    spa->spa_ddt_capped, src);
+
 		spa_prop_add_list(*nvp, ZPOOL_PROP_HEALTH, NULL,
 		    rvd->vdev_state, src);
 
@@ -306,11 +291,12 @@
 		 */
 		if (pool->dp_free_dir != NULL) {
 			spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING, NULL,
-			    dsl_dir_phys(pool->dp_free_dir)->dd_used_bytes,
+			    dsl_dir_phys(pool->dp_free_dir)->dd_used_bytes +
+			    pool->dp_long_freeing_total,
 			    src);
 		} else {
 			spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING,
-			    NULL, 0, src);
+			    NULL, pool->dp_long_freeing_total, src);
 		}
 
 		if (pool->dp_leak_dir != NULL) {
@@ -390,7 +376,7 @@
 		zprop_source_t src = ZPROP_SRC_DEFAULT;
 		zpool_prop_t prop;
 
-		if ((prop = zpool_name_to_prop(za.za_name)) == ZPOOL_PROP_INVAL)
+		if ((prop = zpool_name_to_prop(za.za_name)) == ZPROP_INVAL)
 			continue;
 
 		switch (za.za_integer_length) {
@@ -469,6 +455,8 @@
 	int error = 0, reset_bootfs = 0;
 	uint64_t objnum = 0;
 	boolean_t has_feature = B_FALSE;
+	uint64_t lowat = spa->spa_lowat, hiwat = spa->spa_hiwat,
+	    minwat = spa->spa_minwat;
 
 	elem = NULL;
 	while ((elem = nvlist_next_nvpair(props, elem)) != NULL) {
@@ -476,9 +464,10 @@
 		char *strval, *slash, *check, *fname;
 		const char *propname = nvpair_name(elem);
 		zpool_prop_t prop = zpool_name_to_prop(propname);
+		spa_feature_t feature;
 
 		switch (prop) {
-		case ZPOOL_PROP_INVAL:
+		case ZPROP_INVAL:
 			if (!zpool_prop_feature(propname)) {
 				error = SET_ERROR(EINVAL);
 				break;
@@ -503,11 +492,17 @@
 			}
 
 			fname = strchr(propname, '@') + 1;
-			if (zfeature_lookup_name(fname, NULL) != 0) {
+			if (zfeature_lookup_name(fname, &feature) != 0) {
 				error = SET_ERROR(EINVAL);
 				break;
 			}
 
+			if (feature == SPA_FEATURE_WBC &&
+			    !spa_has_special(spa)) {
+				error = SET_ERROR(ENOTSUP);
+				break;
+			}
+
 			has_feature = B_TRUE;
 			break;
 
@@ -524,11 +519,35 @@
 		case ZPOOL_PROP_AUTOREPLACE:
 		case ZPOOL_PROP_LISTSNAPS:
 		case ZPOOL_PROP_AUTOEXPAND:
+		case ZPOOL_PROP_DEDUP_BEST_EFFORT:
+		case ZPOOL_PROP_DDT_DESEGREGATION:
+		case ZPOOL_PROP_META_PLACEMENT:
+		case ZPOOL_PROP_FORCETRIM:
+		case ZPOOL_PROP_AUTOTRIM:
 			error = nvpair_value_uint64(elem, &intval);
 			if (!error && intval > 1)
 				error = SET_ERROR(EINVAL);
 			break;
 
+		case ZPOOL_PROP_DDT_META_TO_METADEV:
+		case ZPOOL_PROP_ZFS_META_TO_METADEV:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && intval > META_PLACEMENT_DUAL)
+				error = SET_ERROR(EINVAL);
+			break;
+
+		case ZPOOL_PROP_SYNC_TO_SPECIAL:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && intval > SYNC_TO_SPECIAL_ALWAYS)
+				error = SET_ERROR(EINVAL);
+			break;
+
+		case ZPOOL_PROP_SMALL_DATA_TO_METADEV:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && intval > SPA_MAXBLOCKSIZE)
+				error = SET_ERROR(EINVAL);
+			break;
+
 		case ZPOOL_PROP_BOOTFS:
 			/*
 			 * If the pool version is less than SPA_VERSION_BOOTFS,
@@ -586,6 +605,20 @@
 			}
 			break;
 
+		case ZPOOL_PROP_DEDUP_LO_BEST_EFFORT:
+			error = nvpair_value_uint64(elem, &intval);
+			if ((intval < 0) || (intval > 100) ||
+			    (intval >= spa->spa_dedup_hi_best_effort))
+				error = SET_ERROR(EINVAL);
+			break;
+
+		case ZPOOL_PROP_DEDUP_HI_BEST_EFFORT:
+			error = nvpair_value_uint64(elem, &intval);
+			if ((intval < 0) || (intval > 100) ||
+			    (intval <= spa->spa_dedup_lo_best_effort))
+				error = SET_ERROR(EINVAL);
+			break;
+
 		case ZPOOL_PROP_FAILUREMODE:
 			error = nvpair_value_uint64(elem, &intval);
 			if (!error && (intval < ZIO_FAILURE_MODE_WAIT ||
@@ -647,7 +680,7 @@
 				}
 			}
 			if (strlen(strval) > ZPROP_MAX_COMMENT)
-				error = E2BIG;
+				error = SET_ERROR(E2BIG);
 			break;
 
 		case ZPOOL_PROP_DEDUPDITTO:
@@ -659,6 +692,36 @@
 			    intval != 0 && intval < ZIO_DEDUPDITTO_MIN)
 				error = SET_ERROR(EINVAL);
 			break;
+
+		case ZPOOL_PROP_MINWATERMARK:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && (intval > 100))
+				error = SET_ERROR(EINVAL);
+			minwat = intval;
+			break;
+		case ZPOOL_PROP_LOWATERMARK:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && (intval > 100))
+				error = SET_ERROR(EINVAL);
+			lowat = intval;
+			break;
+		case ZPOOL_PROP_HIWATERMARK:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && (intval > 100))
+				error = SET_ERROR(EINVAL);
+			hiwat = intval;
+			break;
+		case ZPOOL_PROP_DEDUPMETA_DITTO:
+			error = nvpair_value_uint64(elem, &intval);
+			if (!error && (intval > SPA_DVAS_PER_BP))
+				error = SET_ERROR(EINVAL);
+			break;
+		case ZPOOL_PROP_SCRUB_PRIO:
+		case ZPOOL_PROP_RESILVER_PRIO:
+			error = nvpair_value_uint64(elem, &intval);
+			if (error || intval > 100)
+				error = SET_ERROR(EINVAL);
+			break;
 		}
 
 		if (error)
@@ -665,6 +728,14 @@
 			break;
 	}
 
+	/* check if low watermark is less than high watermark */
+	if (lowat != 0 && lowat >= hiwat)
+		error = SET_ERROR(EINVAL);
+
+	/* check if min watermark is less than low watermark */
+	if (minwat != 0 && minwat >= lowat)
+		error = SET_ERROR(EINVAL);
+
 	if (!error && reset_bootfs) {
 		error = nvlist_remove(props,
 		    zpool_prop_to_name(ZPOOL_PROP_BOOTFS), DATA_TYPE_STRING);
@@ -721,7 +792,7 @@
 		    prop == ZPOOL_PROP_READONLY)
 			continue;
 
-		if (prop == ZPOOL_PROP_VERSION || prop == ZPOOL_PROP_INVAL) {
+		if (prop == ZPOOL_PROP_VERSION || prop == ZPROP_INVAL) {
 			uint64_t ver;
 
 			if (prop == ZPOOL_PROP_VERSION) {
@@ -840,7 +911,7 @@
 	    spa_change_guid_sync, &guid, 5, ZFS_SPACE_CHECK_RESERVED);
 
 	if (error == 0) {
-		spa_write_cachefile(spa, B_FALSE, B_TRUE);
+		spa_config_sync(spa, B_FALSE, B_TRUE);
 		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_REGUID);
 	}
 
@@ -1108,6 +1179,7 @@
 
 	spa->spa_normal_class = metaslab_class_create(spa, zfs_metaslab_ops);
 	spa->spa_log_class = metaslab_class_create(spa, zfs_metaslab_ops);
+	spa->spa_special_class = metaslab_class_create(spa, zfs_metaslab_ops);
 
 	/* Try to create a covering process */
 	mutex_enter(&spa->spa_proc_lock);
@@ -1142,9 +1214,6 @@
 		spa_create_zio_taskqs(spa);
 	}
 
-	for (size_t i = 0; i < TXG_SIZE; i++)
-		spa->spa_txg_zio[i] = zio_root(spa, NULL, NULL, 0);
-
 	list_create(&spa->spa_config_dirty_list, sizeof (vdev_t),
 	    offsetof(vdev_t, vdev_config_dirty_node));
 	list_create(&spa->spa_evicting_os_list, sizeof (objset_t),
@@ -1189,12 +1258,6 @@
 		}
 	}
 
-	for (size_t i = 0; i < TXG_SIZE; i++) {
-		ASSERT3P(spa->spa_txg_zio[i], !=, NULL);
-		VERIFY0(zio_wait(spa->spa_txg_zio[i]));
-		spa->spa_txg_zio[i] = NULL;
-	}
-
 	metaslab_class_destroy(spa->spa_normal_class);
 	spa->spa_normal_class = NULL;
 
@@ -1201,6 +1264,9 @@
 	metaslab_class_destroy(spa->spa_log_class);
 	spa->spa_log_class = NULL;
 
+	metaslab_class_destroy(spa->spa_special_class);
+	spa->spa_special_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.
@@ -1295,7 +1361,15 @@
 
 	ASSERT(MUTEX_HELD(&spa_namespace_lock));
 
-	spa_load_note(spa, "UNLOADING");
+	/*
+	 * Stop manual trim before stopping spa sync, because manual trim
+	 * needs to execute a synctask (trim timestamp sync) at the end.
+	 */
+	mutex_enter(&spa->spa_auto_trim_lock);
+	mutex_enter(&spa->spa_man_trim_lock);
+	spa_trim_stop_wait(spa);
+	mutex_exit(&spa->spa_man_trim_lock);
+	mutex_exit(&spa->spa_auto_trim_lock);
 
 	/*
 	 * Stop async tasks.
@@ -1333,24 +1407,19 @@
 		spa->spa_async_zio_root = NULL;
 	}
 
-	if (spa->spa_vdev_removal != NULL) {
-		spa_vdev_removal_destroy(spa->spa_vdev_removal);
-		spa->spa_vdev_removal = NULL;
-	}
-
-	if (spa->spa_condense_zthr != NULL) {
-		ASSERT(!zthr_isrunning(spa->spa_condense_zthr));
-		zthr_destroy(spa->spa_condense_zthr);
-		spa->spa_condense_zthr = NULL;
-	}
-
-	spa_condense_fini(spa);
-
 	bpobj_close(&spa->spa_deferred_bpobj);
 
 	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
 
 	/*
+	 * Stop autotrim tasks.
+	 */
+	mutex_enter(&spa->spa_auto_trim_lock);
+	if (spa->spa_auto_trim_taskq)
+		spa_auto_trim_taskq_destroy(spa);
+	mutex_exit(&spa->spa_auto_trim_lock);
+
+	/*
 	 * Close all vdevs.
 	 */
 	if (spa->spa_root_vdev)
@@ -1403,8 +1472,6 @@
 
 	spa->spa_async_suspended = 0;
 
-	spa->spa_indirect_vdevs_loaded = B_FALSE;
-
 	if (spa->spa_comment != NULL) {
 		spa_strfree(spa->spa_comment);
 		spa->spa_comment = NULL;
@@ -1419,7 +1486,7 @@
  * 'spa_spares.sav_config'.  We parse this into vdevs, try to open them, and
  * then re-generate a more complete list including status information.
  */
-void
+static void
 spa_load_spares(spa_t *spa)
 {
 	nvlist_t **spares;
@@ -1536,7 +1603,7 @@
  * Devices which are already active have their details maintained, and are
  * not re-opened.
  */
-void
+static void
 spa_load_l2cache(spa_t *spa)
 {
 	nvlist_t **l2cache;
@@ -1607,8 +1674,14 @@
 
 			(void) vdev_validate_aux(vd);
 
-			if (!vdev_is_dead(vd))
-				l2arc_add_vdev(spa, vd);
+			if (!vdev_is_dead(vd)) {
+				boolean_t do_rebuild = B_FALSE;
+
+				(void) nvlist_lookup_boolean_value(l2cache[i],
+				    ZPOOL_CONFIG_L2CACHE_PERSISTENT,
+				    &do_rebuild);
+				l2arc_add_vdev(spa, vd, do_rebuild);
+			}
 		}
 	}
 
@@ -1686,27 +1759,6 @@
 }
 
 /*
- * Concrete top-level vdevs that are not missing and are not logs. At every
- * spa_sync we write new uberblocks to at least SPA_SYNC_MIN_VDEVS core tvds.
- */
-static uint64_t
-spa_healthy_core_tvds(spa_t *spa)
-{
-	vdev_t *rvd = spa->spa_root_vdev;
-	uint64_t tvds = 0;
-
-	for (uint64_t i = 0; i < rvd->vdev_children; i++) {
-		vdev_t *vd = rvd->vdev_child[i];
-		if (vd->vdev_islog)
-			continue;
-		if (vdev_is_concrete(vd) && !vdev_is_dead(vd))
-			tvds++;
-	}
-
-	return (tvds);
-}
-
-/*
  * Checks to see if the given vdev could not be opened, in which case we post a
  * sysevent to notify the autoreplace code that the device has been removed.
  */
@@ -1713,24 +1765,55 @@
 static void
 spa_check_removed(vdev_t *vd)
 {
-	for (uint64_t c = 0; c < vd->vdev_children; c++)
+	for (int c = 0; c < vd->vdev_children; c++)
 		spa_check_removed(vd->vdev_child[c]);
 
 	if (vd->vdev_ops->vdev_op_leaf && vdev_is_dead(vd) &&
-	    vdev_is_concrete(vd)) {
+	    !vd->vdev_ishole) {
 		zfs_post_autoreplace(vd->vdev_spa, vd);
 		spa_event_notify(vd->vdev_spa, vd, NULL, ESC_ZFS_VDEV_CHECK);
 	}
 }
 
-static int
-spa_check_for_missing_logs(spa_t *spa)
+static void
+spa_config_valid_zaps(vdev_t *vd, vdev_t *mvd)
 {
-	vdev_t *rvd = spa->spa_root_vdev;
+	ASSERT3U(vd->vdev_children, ==, mvd->vdev_children);
 
+	vd->vdev_top_zap = mvd->vdev_top_zap;
+	vd->vdev_leaf_zap = mvd->vdev_leaf_zap;
+
+	for (uint64_t i = 0; i < vd->vdev_children; i++) {
+		spa_config_valid_zaps(vd->vdev_child[i], mvd->vdev_child[i]);
+	}
+}
+
+/*
+ * Validate the current config against the MOS config
+ */
+static boolean_t
+spa_config_valid(spa_t *spa, nvlist_t *config)
+{
+	vdev_t *mrvd, *rvd = spa->spa_root_vdev;
+	nvlist_t *nv;
+
+	VERIFY(nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nv) == 0);
+
+	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+	VERIFY(spa_config_parse(spa, &mrvd, nv, NULL, 0, VDEV_ALLOC_LOAD) == 0);
+
 	/*
+	 * One of the earliest signs of a stale config is a mismatch
+	 * in the numbers of children vdev's
+	 */
+	if (rvd->vdev_children != mrvd->vdev_children) {
+		vdev_free(mrvd);
+		spa_config_exit(spa, SCL_ALL, FTAG);
+		return (B_FALSE);
+	}
+	/*
 	 * If we're doing a normal import, then build up any additional
-	 * diagnostic information about missing log devices.
+	 * diagnostic information about missing devices in this config.
 	 * We'll pass this up to the user for further processing.
 	 */
 	if (!(spa->spa_import_flags & ZFS_IMPORT_MISSING_LOG)) {
@@ -1741,52 +1824,106 @@
 		    KM_SLEEP);
 		VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
 
-		for (uint64_t c = 0; c < rvd->vdev_children; c++) {
+		for (int c = 0; c < rvd->vdev_children; c++) {
 			vdev_t *tvd = rvd->vdev_child[c];
+			vdev_t *mtvd  = mrvd->vdev_child[c];
 
-			/*
-			 * We consider a device as missing only if it failed
-			 * to open (i.e. offline or faulted is not considered
-			 * as missing).
-			 */
-			if (tvd->vdev_islog &&
-			    tvd->vdev_state == VDEV_STATE_CANT_OPEN) {
-				child[idx++] = vdev_config_generate(spa, tvd,
-				    B_FALSE, VDEV_CONFIG_MISSING);
-			}
+			if (tvd->vdev_ops == &vdev_missing_ops &&
+			    mtvd->vdev_ops != &vdev_missing_ops &&
+			    mtvd->vdev_islog)
+				child[idx++] = vdev_config_generate(spa, mtvd,
+				    B_FALSE, 0);
 		}
 
-		if (idx > 0) {
-			fnvlist_add_nvlist_array(nv,
-			    ZPOOL_CONFIG_CHILDREN, child, idx);
-			fnvlist_add_nvlist(spa->spa_load_info,
-			    ZPOOL_CONFIG_MISSING_DEVICES, nv);
+		if (idx) {
+			VERIFY(nvlist_add_nvlist_array(nv,
+			    ZPOOL_CONFIG_CHILDREN, child, idx) == 0);
+			VERIFY(nvlist_add_nvlist(spa->spa_load_info,
+			    ZPOOL_CONFIG_MISSING_DEVICES, nv) == 0);
 
-			for (uint64_t i = 0; i < idx; i++)
+			for (int i = 0; i < idx; i++)
 				nvlist_free(child[i]);
 		}
 		nvlist_free(nv);
 		kmem_free(child, rvd->vdev_children * sizeof (char **));
+	}
 
-		if (idx > 0) {
-			spa_load_failed(spa, "some log devices are missing");
-			return (SET_ERROR(ENXIO));
-		}
-	} else {
-		for (uint64_t c = 0; c < rvd->vdev_children; c++) {
-			vdev_t *tvd = rvd->vdev_child[c];
+	/*
+	 * Compare the root vdev tree with the information we have
+	 * from the MOS config (mrvd). Check each top-level vdev
+	 * with the corresponding MOS config top-level (mtvd).
+	 */
+	for (int c = 0; c < rvd->vdev_children; c++) {
+		vdev_t *tvd = rvd->vdev_child[c];
+		vdev_t *mtvd  = mrvd->vdev_child[c];
 
-			if (tvd->vdev_islog &&
-			    tvd->vdev_state == VDEV_STATE_CANT_OPEN) {
+		/*
+		 * Resolve any "missing" vdevs in the current configuration.
+		 * If we find that the MOS config has more accurate information
+		 * about the top-level vdev then use that vdev instead.
+		 */
+		if (tvd->vdev_ops == &vdev_missing_ops &&
+		    mtvd->vdev_ops != &vdev_missing_ops) {
+
+			if (!(spa->spa_import_flags & ZFS_IMPORT_MISSING_LOG))
+				continue;
+
+			/*
+			 * Device specific actions.
+			 */
+			if (mtvd->vdev_islog) {
 				spa_set_log_state(spa, SPA_LOG_CLEAR);
-				spa_load_note(spa, "some log devices are "
-				    "missing, ZIL is dropped.");
-				break;
+			} else {
+				/*
+				 * XXX - once we have 'readonly' pool
+				 * support we should be able to handle
+				 * missing data devices by transitioning
+				 * the pool to readonly.
+				 */
+				continue;
 			}
+
+			/*
+			 * Swap the missing vdev with the data we were
+			 * able to obtain from the MOS config.
+			 */
+			vdev_remove_child(rvd, tvd);
+			vdev_remove_child(mrvd, mtvd);
+
+			vdev_add_child(rvd, mtvd);
+			vdev_add_child(mrvd, tvd);
+
+			spa_config_exit(spa, SCL_ALL, FTAG);
+			vdev_load(mtvd);
+			spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+
+			vdev_reopen(rvd);
+		} else {
+			if (mtvd->vdev_islog) {
+				/*
+				 * Load the slog device's state from the MOS
+				 * config since it's possible that the label
+				 * does not contain the most up-to-date
+				 * information.
+				 */
+				vdev_load_log_state(tvd, mtvd);
+				vdev_reopen(tvd);
+			}
+
+			/*
+			 * Per-vdev ZAP info is stored exclusively in the MOS.
+			 */
+			spa_config_valid_zaps(tvd, mtvd);
 		}
 	}
 
-	return (0);
+	vdev_free(mrvd);
+	spa_config_exit(spa, SCL_ALL, FTAG);
+
+	/*
+	 * Ensure we were able to validate the config.
+	 */
+	return (rvd->vdev_guid_sum == spa->spa_uberblock.ub_guid_sum);
 }
 
 /*
@@ -1852,11 +1989,11 @@
 }
 
 int
-spa_reset_logs(spa_t *spa)
+spa_offline_log(spa_t *spa)
 {
 	int error;
 
-	error = dmu_objset_find(spa_name(spa), zil_reset,
+	error = dmu_objset_find(spa_name(spa), zil_vdev_offline,
 	    NULL, DS_FIND_CHILDREN);
 	if (error == 0) {
 		/*
@@ -1906,8 +2043,7 @@
 
 	abd_free(zio->io_abd);
 	if (error) {
-		if ((BP_GET_LEVEL(bp) != 0 || DMU_OT_IS_METADATA(type)) &&
-		    type != DMU_OT_INTENT_LOG)
+		if (BP_IS_METADATA(bp) && type != DMU_OT_INTENT_LOG)
 			atomic_inc_64(&sle->sle_meta_count);
 		else
 			atomic_inc_64(&sle->sle_data_count);
@@ -1996,16 +2132,10 @@
 	    ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
 
 	if (spa_load_verify_metadata) {
-		if (spa->spa_extreme_rewind) {
-			spa_load_note(spa, "performing a complete scan of the "
-			    "pool since extreme rewind is on. This may take "
-			    "a very long time.\n  (spa_load_verify_data=%u, "
-			    "spa_load_verify_metadata=%u)",
-			    spa_load_verify_data, spa_load_verify_metadata);
-		}
-		error = traverse_pool(spa, spa->spa_verify_min_txg,
+		zbookmark_phys_t zb = { 0 };
+		error = traverse_pool(spa, spa->spa_verify_min_txg, UINT64_MAX,
 		    TRAVERSE_PRE | TRAVERSE_PREFETCH_METADATA,
-		    spa_load_verify_cb, rio);
+		    spa_load_verify_cb, rio, &zb);
 	}
 
 	(void) zio_wait(rio);
@@ -2013,15 +2143,8 @@
 	spa->spa_load_meta_errors = sle.sle_meta_count;
 	spa->spa_load_data_errors = sle.sle_data_count;
 
-	if (sle.sle_meta_count != 0 || sle.sle_data_count != 0) {
-		spa_load_note(spa, "spa_load_verify found %llu metadata errors "
-		    "and %llu data errors", (u_longlong_t)sle.sle_meta_count,
-		    (u_longlong_t)sle.sle_data_count);
-	}
-
-	if (spa_load_verify_dryrun ||
-	    (!error && sle.sle_meta_count <= policy.zrp_maxmeta &&
-	    sle.sle_data_count <= policy.zrp_maxdata)) {
+	if (!error && sle.sle_meta_count <= policy.zrp_maxmeta &&
+	    sle.sle_data_count <= policy.zrp_maxdata) {
 		int64_t loss = 0;
 
 		verify_ok = B_TRUE;
@@ -2039,9 +2162,6 @@
 		spa->spa_load_max_txg = spa->spa_uberblock.ub_txg;
 	}
 
-	if (spa_load_verify_dryrun)
-		return (0);
-
 	if (error) {
 		if (error != ENXIO && error != EIO)
 			error = SET_ERROR(EIO);
@@ -2065,17 +2185,25 @@
  * Find a value in the pool directory object.
  */
 static int
-spa_dir_prop(spa_t *spa, const char *name, uint64_t *val, boolean_t log_enoent)
+spa_dir_prop(spa_t *spa, const char *name, uint64_t *val)
 {
-	int error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
-	    name, sizeof (uint64_t), 1, val);
+	return (zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    name, sizeof (uint64_t), 1, val));
+}
 
-	if (error != 0 && (error != ENOENT || log_enoent)) {
-		spa_load_failed(spa, "couldn't get '%s' value in MOS directory "
-		    "[error=%d]", name, error);
+static void
+spa_set_ddt_classes(spa_t *spa, int desegregation)
+{
+	/*
+	 * if desegregation is turned on then set up ddt_class restrictions
+	 */
+	if (desegregation) {
+		spa->spa_ddt_class_min = DDT_CLASS_DUPLICATE;
+		spa->spa_ddt_class_max = DDT_CLASS_DUPLICATE;
+	} else {
+		spa->spa_ddt_class_min = DDT_CLASS_DITTO;
+		spa->spa_ddt_class_max = DDT_CLASS_UNIQUE;
 	}
-
-	return (error);
 }
 
 static int
@@ -2082,19 +2210,9 @@
 spa_vdev_err(vdev_t *vdev, vdev_aux_t aux, int err)
 {
 	vdev_set_state(vdev, B_TRUE, VDEV_STATE_CANT_OPEN, aux);
-	return (SET_ERROR(err));
+	return (err);
 }
 
-static void
-spa_spawn_aux_threads(spa_t *spa)
-{
-	ASSERT(spa_writeable(spa));
-
-	ASSERT(MUTEX_HELD(&spa_namespace_lock));
-
-	spa_start_indirect_condensing_thread(spa);
-}
-
 /*
  * Fix up config after a partly-completed split.  This is done with the
  * ZPOOL_CONFIG_SPLIT nvlist.  Both the splitting pool and the split-off
@@ -2178,17 +2296,55 @@
 }
 
 static int
-spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type)
+spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type,
+    boolean_t mosconfig)
 {
+	nvlist_t *config = spa->spa_config;
 	char *ereport = FM_EREPORT_ZFS_POOL;
+	char *comment;
 	int error;
+	uint64_t pool_guid;
+	nvlist_t *nvl;
 
-	spa->spa_load_state = state;
+	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid))
+		return (SET_ERROR(EINVAL));
 
-	gethrestime(&spa->spa_loaded_ts);
-	error = spa_load_impl(spa, type, &ereport, B_FALSE);
+	ASSERT(spa->spa_comment == NULL);
+	if (nvlist_lookup_string(config, ZPOOL_CONFIG_COMMENT, &comment) == 0)
+		spa->spa_comment = spa_strdup(comment);
 
 	/*
+	 * 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,
+	    &spa->spa_ubsync.ub_version) != 0)
+		spa->spa_ubsync.ub_version = SPA_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 = SET_ERROR(EEXIST);
+	} else {
+		spa->spa_config_guid = pool_guid;
+
+		if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT,
+		    &nvl) == 0) {
+			VERIFY(nvlist_dup(nvl, &spa->spa_config_splitting,
+			    KM_SLEEP) == 0);
+		}
+
+		nvlist_free(spa->spa_load_info);
+		spa->spa_load_info = fnvlist_alloc();
+
+		gethrestime(&spa->spa_loaded_ts);
+		error = spa_load_impl(spa, pool_guid, config, state, type,
+		    mosconfig, &ereport);
+	}
+
+	/*
 	 * Don't count references from objsets that are already closed
 	 * and are making their way through the eviction process.
 	 */
@@ -2205,7 +2361,6 @@
 	}
 	spa->spa_load_state = error ? SPA_LOAD_ERROR : SPA_LOAD_NONE;
 	spa->spa_ena = 0;
-
 	return (error);
 }
 
@@ -2237,88 +2392,44 @@
 	return (total);
 }
 
+/*
+ * Load an existing storage pool, using the pool's builtin spa_config as a
+ * source of configuration information.
+ */
 static int
-spa_verify_host(spa_t *spa, nvlist_t *mos_config)
+spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
+    spa_load_state_t state, spa_import_type_t type, boolean_t mosconfig,
+    char **ereport)
 {
-	uint64_t hostid;
-	char *hostname;
-	uint64_t myhostid = 0;
-
-	if (!spa_is_root(spa) && nvlist_lookup_uint64(mos_config,
-	    ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
-		hostname = fnvlist_lookup_string(mos_config,
-		    ZPOOL_CONFIG_HOSTNAME);
-
-		myhostid = zone_get_hostid(NULL);
-
-		if (hostid != 0 && myhostid != 0 && hostid != myhostid) {
-			cmn_err(CE_WARN, "pool '%s' could not be "
-			    "loaded as it was last accessed by "
-			    "another system (host: %s hostid: 0x%llx). "
-			    "See: http://illumos.org/msg/ZFS-8000-EY",
-			    spa_name(spa), hostname, (u_longlong_t)hostid);
-			spa_load_failed(spa, "hostid verification failed: pool "
-			    "last accessed by host: %s (hostid: 0x%llx)",
-			    hostname, (u_longlong_t)hostid);
-			return (SET_ERROR(EBADF));
-		}
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_parse_config(spa_t *spa, spa_import_type_t type)
-{
 	int error = 0;
-	nvlist_t *nvtree, *nvl, *config = spa->spa_config;
-	int parse;
+	nvlist_t *nvroot = NULL;
+	nvlist_t *label;
 	vdev_t *rvd;
-	uint64_t pool_guid;
-	char *comment;
+	uberblock_t *ub = &spa->spa_uberblock;
+	uint64_t children, config_cache_txg = spa->spa_config_txg;
+	int orig_mode = spa->spa_mode;
+	int parse;
+	uint64_t obj;
+	boolean_t missing_feat_write = B_FALSE;
+	spa_meta_placement_t *mp;
 
 	/*
-	 * Versioning wasn't explicitly added to the label until later, so if
-	 * it's not present treat it as the initial version.
+	 * If this is an untrusted config, access the pool in read-only mode.
+	 * This prevents things like resilvering recently removed devices.
 	 */
-	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION,
-	    &spa->spa_ubsync.ub_version) != 0)
-		spa->spa_ubsync.ub_version = SPA_VERSION_INITIAL;
+	if (!mosconfig)
+		spa->spa_mode = FREAD;
 
-	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid)) {
-		spa_load_failed(spa, "invalid config provided: '%s' missing",
-		    ZPOOL_CONFIG_POOL_GUID);
-		return (SET_ERROR(EINVAL));
-	}
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
 
-	if ((spa->spa_load_state == SPA_LOAD_IMPORT || spa->spa_load_state ==
-	    SPA_LOAD_TRYIMPORT) && spa_guid_exists(pool_guid, 0)) {
-		spa_load_failed(spa, "a pool with guid %llu is already open",
-		    (u_longlong_t)pool_guid);
-		return (SET_ERROR(EEXIST));
-	}
+	spa->spa_load_state = state;
 
-	spa->spa_config_guid = pool_guid;
-
-	nvlist_free(spa->spa_load_info);
-	spa->spa_load_info = fnvlist_alloc();
-
-	ASSERT(spa->spa_comment == NULL);
-	if (nvlist_lookup_string(config, ZPOOL_CONFIG_COMMENT, &comment) == 0)
-		spa->spa_comment = spa_strdup(comment);
-
-	(void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG,
-	    &spa->spa_config_txg);
-
-	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT, &nvl) == 0)
-		spa->spa_config_splitting = fnvlist_dup(nvl);
-
-	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvtree)) {
-		spa_load_failed(spa, "invalid config provided: '%s' missing",
-		    ZPOOL_CONFIG_VDEV_TREE);
+	if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvroot))
 		return (SET_ERROR(EINVAL));
-	}
 
+	parse = (type == SPA_IMPORT_EXISTING ?
+	    VDEV_ALLOC_LOAD : VDEV_ALLOC_SPLIT);
+
 	/*
 	 * Create "The Godfather" zio to hold all async IOs
 	 */
@@ -2336,16 +2447,11 @@
 	 * configuration requires knowing the version number.
 	 */
 	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-	parse = (type == SPA_IMPORT_EXISTING ?
-	    VDEV_ALLOC_LOAD : VDEV_ALLOC_SPLIT);
-	error = spa_config_parse(spa, &rvd, nvtree, NULL, 0, parse);
+	error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, parse);
 	spa_config_exit(spa, SCL_ALL, FTAG);
 
-	if (error != 0) {
-		spa_load_failed(spa, "unable to parse config [error=%d]",
-		    error);
+	if (error != 0)
 		return (error);
-	}
 
 	ASSERT(spa->spa_root_vdev == rvd);
 	ASSERT3U(spa->spa_min_ashift, >=, SPA_MINBLOCKSHIFT);
@@ -2355,109 +2461,40 @@
 		ASSERT(spa_guid(spa) == pool_guid);
 	}
 
-	return (0);
-}
-
-/*
- * Recursively open all vdevs in the vdev tree. This function is called twice:
- * first with the untrusted config, then with the trusted config.
- */
-static int
-spa_ld_open_vdevs(spa_t *spa)
-{
-	int error = 0;
-
 	/*
-	 * spa_missing_tvds_allowed defines how many top-level vdevs can be
-	 * missing/unopenable for the root vdev to be still considered openable.
+	 * Try to open all vdevs, loading each label in the process.
 	 */
-	if (spa->spa_trust_config) {
-		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds;
-	} else if (spa->spa_config_source == SPA_CONFIG_SRC_CACHEFILE) {
-		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds_cachefile;
-	} else if (spa->spa_config_source == SPA_CONFIG_SRC_SCAN) {
-		spa->spa_missing_tvds_allowed = zfs_max_missing_tvds_scan;
-	} else {
-		spa->spa_missing_tvds_allowed = 0;
-	}
-
-	spa->spa_missing_tvds_allowed =
-	    MAX(zfs_max_missing_tvds, spa->spa_missing_tvds_allowed);
-
 	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-	error = vdev_open(spa->spa_root_vdev);
+	error = vdev_open(rvd);
 	spa_config_exit(spa, SCL_ALL, FTAG);
+	if (error != 0)
+		return (error);
 
-	if (spa->spa_missing_tvds != 0) {
-		spa_load_note(spa, "vdev tree has %lld missing top-level "
-		    "vdevs.", (u_longlong_t)spa->spa_missing_tvds);
-		if (spa->spa_trust_config && (spa->spa_mode & FWRITE)) {
-			/*
-			 * Although theoretically we could allow users to open
-			 * incomplete pools in RW mode, we'd need to add a lot
-			 * of extra logic (e.g. adjust pool space to account
-			 * for missing vdevs).
-			 * This limitation also prevents users from accidentally
-			 * opening the pool in RW mode during data recovery and
-			 * damaging it further.
-			 */
-			spa_load_note(spa, "pools with missing top-level "
-			    "vdevs can only be opened in read-only mode.");
-			error = SET_ERROR(ENXIO);
-		} else {
-			spa_load_note(spa, "current settings allow for maximum "
-			    "%lld missing top-level vdevs at this stage.",
-			    (u_longlong_t)spa->spa_missing_tvds_allowed);
-		}
-	}
-	if (error != 0) {
-		spa_load_failed(spa, "unable to open vdev tree [error=%d]",
-		    error);
-	}
-	if (spa->spa_missing_tvds != 0 || error != 0)
-		vdev_dbgmsg_print_tree(spa->spa_root_vdev, 2);
+	/*
+	 * We need to validate the vdev labels against the configuration that
+	 * we have in hand, which is dependent on the setting of mosconfig. If
+	 * mosconfig is true then we're validating the vdev labels based on
+	 * that config.  Otherwise, we're validating against the cached config
+	 * (zpool.cache) that was read when we loaded the zfs module, and then
+	 * later we will recursively call spa_load() and validate against
+	 * the vdev config.
+	 *
+	 * If we're assembling a new pool that's been split off from an
+	 * existing pool, the labels haven't yet been updated so we skip
+	 * validation for now.
+	 */
+	if (type != SPA_IMPORT_ASSEMBLE) {
+		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+		error = vdev_validate(rvd, mosconfig);
+		spa_config_exit(spa, SCL_ALL, FTAG);
 
-	return (error);
-}
+		if (error != 0)
+			return (error);
 
-/*
- * We need to validate the vdev labels against the configuration that
- * we have in hand. This function is called twice: first with an untrusted
- * config, then with a trusted config. The validation is more strict when the
- * config is trusted.
- */
-static int
-spa_ld_validate_vdevs(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
-	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-	error = vdev_validate(rvd);
-	spa_config_exit(spa, SCL_ALL, FTAG);
-
-	if (error != 0) {
-		spa_load_failed(spa, "vdev_validate failed [error=%d]", error);
-		return (error);
+		if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN)
+			return (SET_ERROR(ENXIO));
 	}
 
-	if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
-		spa_load_failed(spa, "cannot open vdev tree after invalidating "
-		    "some vdevs");
-		vdev_dbgmsg_print_tree(rvd, 2);
-		return (SET_ERROR(ENXIO));
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_select_uberblock(spa_t *spa, spa_import_type_t type)
-{
-	vdev_t *rvd = spa->spa_root_vdev;
-	nvlist_t *label;
-	uberblock_t *ub = &spa->spa_uberblock;
-
 	/*
 	 * Find the best uberblock.
 	 */
@@ -2468,20 +2505,14 @@
 	 */
 	if (ub->ub_txg == 0) {
 		nvlist_free(label);
-		spa_load_failed(spa, "no valid uberblock found");
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, ENXIO));
 	}
 
-	spa_load_note(spa, "using uberblock with txg=%llu",
-	    (u_longlong_t)ub->ub_txg);
-
 	/*
 	 * If the pool has an unsupported version we can't open it.
 	 */
 	if (!SPA_VERSION_IS_SUPPORTED(ub->ub_version)) {
 		nvlist_free(label);
-		spa_load_failed(spa, "version %llu is not supported",
-		    (u_longlong_t)ub->ub_version);
 		return (spa_vdev_err(rvd, VDEV_AUX_VERSION_NEWER, ENOTSUP));
 	}
 
@@ -2492,17 +2523,9 @@
 		 * If we weren't able to find what's necessary for reading the
 		 * MOS in the label, return failure.
 		 */
-		if (label == NULL) {
-			spa_load_failed(spa, "label config unavailable");
-			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
-			    ENXIO));
-		}
-
-		if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_FEATURES_FOR_READ,
-		    &features) != 0) {
+		if (label == NULL || nvlist_lookup_nvlist(label,
+		    ZPOOL_CONFIG_FEATURES_FOR_READ, &features) != 0) {
 			nvlist_free(label);
-			spa_load_failed(spa, "invalid label: '%s' missing",
-			    ZPOOL_CONFIG_FEATURES_FOR_READ);
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
 			    ENXIO));
 		}
@@ -2541,7 +2564,6 @@
 			VERIFY(nvlist_add_nvlist(spa->spa_load_info,
 			    ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat) == 0);
 			nvlist_free(unsup_feat);
-			spa_load_failed(spa, "some features are unsupported");
 			return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
 			    ENOTSUP));
 		}
@@ -2549,9 +2571,21 @@
 		nvlist_free(unsup_feat);
 	}
 
+	/*
+	 * If the vdev guid sum doesn't match the uberblock, we have an
+	 * incomplete configuration.  We first check to see if the pool
+	 * is aware of the complete config (i.e ZPOOL_CONFIG_VDEV_CHILDREN).
+	 * If it is, defer the vdev_guid_sum check till later so we
+	 * can handle missing vdevs.
+	 */
+	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VDEV_CHILDREN,
+	    &children) != 0 && mosconfig && type != SPA_IMPORT_ASSEMBLE &&
+	    rvd->vdev_guid_sum != ub->ub_guid_sum)
+		return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM, ENXIO));
+
 	if (type != SPA_IMPORT_ASSEMBLE && spa->spa_config_splitting) {
 		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-		spa_try_repair(spa, spa->spa_config);
+		spa_try_repair(spa, config);
 		spa_config_exit(spa, SCL_ALL, FTAG);
 		nvlist_free(spa->spa_config_splitting);
 		spa->spa_config_splitting = NULL;
@@ -2569,243 +2603,30 @@
 	spa->spa_claim_max_txg = spa->spa_first_txg;
 	spa->spa_prev_software_version = ub->ub_software_version;
 
-	return (0);
-}
-
-static int
-spa_ld_open_rootbp(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
 	error = dsl_pool_init(spa, spa->spa_first_txg, &spa->spa_dsl_pool);
-	if (error != 0) {
-		spa_load_failed(spa, "unable to open rootbp in dsl_pool_init "
-		    "[error=%d]", error);
+	if (error)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
 	spa->spa_meta_objset = spa->spa_dsl_pool->dp_meta_objset;
 
-	return (0);
-}
-
-static int
-spa_ld_load_trusted_config(spa_t *spa, spa_import_type_t type,
-    boolean_t reloading)
-{
-	vdev_t *mrvd, *rvd = spa->spa_root_vdev;
-	nvlist_t *nv, *mos_config, *policy;
-	int error = 0, copy_error;
-	uint64_t healthy_tvds, healthy_tvds_mos;
-	uint64_t mos_config_txg;
-
-	if (spa_dir_prop(spa, DMU_POOL_CONFIG, &spa->spa_config_object, B_TRUE)
-	    != 0)
+	if (spa_dir_prop(spa, DMU_POOL_CONFIG, &spa->spa_config_object) != 0)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
-	/*
-	 * If we're assembling a pool from a split, the config provided is
-	 * already trusted so there is nothing to do.
-	 */
-	if (type == SPA_IMPORT_ASSEMBLE)
-		return (0);
-
-	healthy_tvds = spa_healthy_core_tvds(spa);
-
-	if (load_nvlist(spa, spa->spa_config_object, &mos_config)
-	    != 0) {
-		spa_load_failed(spa, "unable to retrieve MOS config");
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
-
-	/*
-	 * If we are doing an open, pool owner wasn't verified yet, thus do
-	 * the verification here.
-	 */
-	if (spa->spa_load_state == SPA_LOAD_OPEN) {
-		error = spa_verify_host(spa, mos_config);
-		if (error != 0) {
-			nvlist_free(mos_config);
-			return (error);
-		}
-	}
-
-	nv = fnvlist_lookup_nvlist(mos_config, ZPOOL_CONFIG_VDEV_TREE);
-
-	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-
-	/*
-	 * Build a new vdev tree from the trusted config
-	 */
-	VERIFY(spa_config_parse(spa, &mrvd, nv, NULL, 0, VDEV_ALLOC_LOAD) == 0);
-
-	/*
-	 * Vdev paths in the MOS may be obsolete. If the untrusted config was
-	 * obtained by scanning /dev/dsk, then it will have the right vdev
-	 * paths. We update the trusted MOS config with this information.
-	 * We first try to copy the paths with vdev_copy_path_strict, which
-	 * succeeds only when both configs have exactly the same vdev tree.
-	 * If that fails, we fall back to a more flexible method that has a
-	 * best effort policy.
-	 */
-	copy_error = vdev_copy_path_strict(rvd, mrvd);
-	if (copy_error != 0 || spa_load_print_vdev_tree) {
-		spa_load_note(spa, "provided vdev tree:");
-		vdev_dbgmsg_print_tree(rvd, 2);
-		spa_load_note(spa, "MOS vdev tree:");
-		vdev_dbgmsg_print_tree(mrvd, 2);
-	}
-	if (copy_error != 0) {
-		spa_load_note(spa, "vdev_copy_path_strict failed, falling "
-		    "back to vdev_copy_path_relaxed");
-		vdev_copy_path_relaxed(rvd, mrvd);
-	}
-
-	vdev_close(rvd);
-	vdev_free(rvd);
-	spa->spa_root_vdev = mrvd;
-	rvd = mrvd;
-	spa_config_exit(spa, SCL_ALL, FTAG);
-
-	/*
-	 * We will use spa_config if we decide to reload the spa or if spa_load
-	 * fails and we rewind. We must thus regenerate the config using the
-	 * MOS information with the updated paths. Rewind policy is an import
-	 * setting and is not in the MOS. We copy it over to our new, trusted
-	 * config.
-	 */
-	mos_config_txg = fnvlist_lookup_uint64(mos_config,
-	    ZPOOL_CONFIG_POOL_TXG);
-	nvlist_free(mos_config);
-	mos_config = spa_config_generate(spa, NULL, mos_config_txg, B_FALSE);
-	if (nvlist_lookup_nvlist(spa->spa_config, ZPOOL_REWIND_POLICY,
-	    &policy) == 0)
-		fnvlist_add_nvlist(mos_config, ZPOOL_REWIND_POLICY, policy);
-	spa_config_set(spa, mos_config);
-	spa->spa_config_source = SPA_CONFIG_SRC_MOS;
-
-	/*
-	 * Now that we got the config from the MOS, we should be more strict
-	 * in checking blkptrs and can make assumptions about the consistency
-	 * of the vdev tree. spa_trust_config must be set to true before opening
-	 * vdevs in order for them to be writeable.
-	 */
-	spa->spa_trust_config = B_TRUE;
-
-	/*
-	 * Open and validate the new vdev tree
-	 */
-	error = spa_ld_open_vdevs(spa);
-	if (error != 0)
-		return (error);
-
-	error = spa_ld_validate_vdevs(spa);
-	if (error != 0)
-		return (error);
-
-	if (copy_error != 0 || spa_load_print_vdev_tree) {
-		spa_load_note(spa, "final vdev tree:");
-		vdev_dbgmsg_print_tree(rvd, 2);
-	}
-
-	if (spa->spa_load_state != SPA_LOAD_TRYIMPORT &&
-	    !spa->spa_extreme_rewind && zfs_max_missing_tvds == 0) {
-		/*
-		 * Sanity check to make sure that we are indeed loading the
-		 * latest uberblock. If we missed SPA_SYNC_MIN_VDEVS tvds
-		 * in the config provided and they happened to be the only ones
-		 * to have the latest uberblock, we could involuntarily perform
-		 * an extreme rewind.
-		 */
-		healthy_tvds_mos = spa_healthy_core_tvds(spa);
-		if (healthy_tvds_mos - healthy_tvds >=
-		    SPA_SYNC_MIN_VDEVS) {
-			spa_load_note(spa, "config provided misses too many "
-			    "top-level vdevs compared to MOS (%lld vs %lld). ",
-			    (u_longlong_t)healthy_tvds,
-			    (u_longlong_t)healthy_tvds_mos);
-			spa_load_note(spa, "vdev tree:");
-			vdev_dbgmsg_print_tree(rvd, 2);
-			if (reloading) {
-				spa_load_failed(spa, "config was already "
-				    "provided from MOS. Aborting.");
-				return (spa_vdev_err(rvd,
-				    VDEV_AUX_CORRUPT_DATA, EIO));
-			}
-			spa_load_note(spa, "spa must be reloaded using MOS "
-			    "config");
-			return (SET_ERROR(EAGAIN));
-		}
-	}
-
-	error = spa_check_for_missing_logs(spa);
-	if (error != 0)
-		return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM, ENXIO));
-
-	if (rvd->vdev_guid_sum != spa->spa_uberblock.ub_guid_sum) {
-		spa_load_failed(spa, "uberblock guid sum doesn't match MOS "
-		    "guid sum (%llu != %llu)",
-		    (u_longlong_t)spa->spa_uberblock.ub_guid_sum,
-		    (u_longlong_t)rvd->vdev_guid_sum);
-		return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM,
-		    ENXIO));
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_open_indirect_vdev_metadata(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
-	/*
-	 * Everything that we read before spa_remove_init() must be stored
-	 * on concreted vdevs.  Therefore we do this as early as possible.
-	 */
-	error = spa_remove_init(spa);
-	if (error != 0) {
-		spa_load_failed(spa, "spa_remove_init failed [error=%d]",
-		    error);
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
-
-	/*
-	 * Retrieve information needed to condense indirect vdev mappings.
-	 */
-	error = spa_condense_init(spa);
-	if (error != 0) {
-		spa_load_failed(spa, "spa_condense_init failed [error=%d]",
-		    error);
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, error));
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_check_features(spa_t *spa, boolean_t *missing_feat_writep)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
 	if (spa_version(spa) >= SPA_VERSION_FEATURES) {
 		boolean_t missing_feat_read = B_FALSE;
 		nvlist_t *unsup_feat, *enabled_feat;
 
 		if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_READ,
-		    &spa->spa_feat_for_read_obj, B_TRUE) != 0) {
+		    &spa->spa_feat_for_read_obj) != 0) {
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 		}
 
 		if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_WRITE,
-		    &spa->spa_feat_for_write_obj, B_TRUE) != 0) {
+		    &spa->spa_feat_for_write_obj) != 0) {
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 		}
 
 		if (spa_dir_prop(spa, DMU_POOL_FEATURE_DESCRIPTIONS,
-		    &spa->spa_feat_desc_obj, B_TRUE) != 0) {
+		    &spa->spa_feat_desc_obj) != 0) {
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 		}
 
@@ -2816,11 +2637,10 @@
 		    unsup_feat, enabled_feat))
 			missing_feat_read = B_TRUE;
 
-		if (spa_writeable(spa) ||
-		    spa->spa_load_state == SPA_LOAD_TRYIMPORT) {
+		if (spa_writeable(spa) || state == SPA_LOAD_TRYIMPORT) {
 			if (!spa_features_check(spa, B_TRUE,
 			    unsup_feat, enabled_feat)) {
-				*missing_feat_writep = B_TRUE;
+				missing_feat_write = B_TRUE;
 			}
 		}
 
@@ -2859,9 +2679,8 @@
 		 * userland in order to know whether to display the
 		 * abovementioned note.
 		 */
-		if (missing_feat_read || (*missing_feat_writep &&
+		if (missing_feat_read || (missing_feat_write &&
 		    spa_writeable(spa))) {
-			spa_load_failed(spa, "pool uses unsupported features");
 			return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
 			    ENOTSUP));
 		}
@@ -2881,9 +2700,6 @@
 				spa->spa_feat_refcount_cache[i] =
 				    SPA_FEATURE_DISABLED;
 			} else {
-				spa_load_failed(spa, "error getting refcount "
-				    "for feature %s [error=%d]",
-				    spa_feature_table[i].fi_guid, error);
 				return (spa_vdev_err(rvd,
 				    VDEV_AUX_CORRUPT_DATA, EIO));
 			}
@@ -2892,37 +2708,65 @@
 
 	if (spa_feature_is_active(spa, SPA_FEATURE_ENABLED_TXG)) {
 		if (spa_dir_prop(spa, DMU_POOL_FEATURE_ENABLED_TXG,
-		    &spa->spa_feat_enabled_txg_obj, B_TRUE) != 0)
+		    &spa->spa_feat_enabled_txg_obj) != 0)
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 	}
 
-	return (0);
-}
-
-static int
-spa_ld_load_special_directories(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
 	spa->spa_is_initializing = B_TRUE;
 	error = dsl_pool_open(spa->spa_dsl_pool);
 	spa->spa_is_initializing = B_FALSE;
-	if (error != 0) {
-		spa_load_failed(spa, "dsl_pool_open failed [error=%d]", error);
+	if (error != 0)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
 
-	return (0);
-}
+	if (!mosconfig) {
+		uint64_t hostid;
+		nvlist_t *policy = NULL, *nvconfig;
 
-static int
-spa_ld_get_props(spa_t *spa)
-{
-	int error = 0;
-	uint64_t obj;
-	vdev_t *rvd = spa->spa_root_vdev;
+		if (load_nvlist(spa, spa->spa_config_object, &nvconfig) != 0)
+			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
+		if (!spa_is_root(spa) && nvlist_lookup_uint64(nvconfig,
+		    ZPOOL_CONFIG_HOSTID, &hostid) == 0) {
+			char *hostname;
+			unsigned long myhostid = 0;
+
+			VERIFY(nvlist_lookup_string(nvconfig,
+			    ZPOOL_CONFIG_HOSTNAME, &hostname) == 0);
+
+#ifdef	_KERNEL
+			myhostid = zone_get_hostid(NULL);
+#else	/* _KERNEL */
+			/*
+			 * We're emulating the system's hostid in userland, so
+			 * we can't use zone_get_hostid().
+			 */
+			(void) ddi_strtoul(hw_serial, NULL, 10, &myhostid);
+#endif	/* _KERNEL */
+			if (hostid != 0 && myhostid != 0 &&
+			    hostid != myhostid) {
+				nvlist_free(nvconfig);
+				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://illumos.org/msg/ZFS-8000-EY",
+				    spa_name(spa), hostname,
+				    (unsigned long)hostid);
+				return (SET_ERROR(EBADF));
+			}
+		}
+		if (nvlist_lookup_nvlist(spa->spa_config,
+		    ZPOOL_REWIND_POLICY, &policy) == 0)
+			VERIFY(nvlist_add_nvlist(nvconfig,
+			    ZPOOL_REWIND_POLICY, policy) == 0);
+
+		spa_config_set(spa, nvconfig);
+		spa_unload(spa);
+		spa_deactivate(spa);
+		spa_activate(spa, orig_mode);
+
+		return (spa_load(spa, state, SPA_IMPORT_EXISTING, B_TRUE));
+	}
+
 	/* Grab the secret checksum salt from the MOS. */
 	error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
 	    DMU_POOL_CHECKSUM_SALT, 1,
@@ -2933,19 +2777,14 @@
 		(void) random_get_pseudo_bytes(spa->spa_cksum_salt.zcs_bytes,
 		    sizeof (spa->spa_cksum_salt.zcs_bytes));
 	} else if (error != 0) {
-		spa_load_failed(spa, "unable to retrieve checksum salt from "
-		    "MOS [error=%d]", error);
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 	}
 
-	if (spa_dir_prop(spa, DMU_POOL_SYNC_BPOBJ, &obj, B_TRUE) != 0)
+	if (spa_dir_prop(spa, DMU_POOL_SYNC_BPOBJ, &obj) != 0)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 	error = bpobj_open(&spa->spa_deferred_bpobj, spa->spa_meta_objset, obj);
-	if (error != 0) {
-		spa_load_failed(spa, "error opening deferred-frees bpobj "
-		    "[error=%d]", error);
+	if (error != 0)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
 
 	/*
 	 * Load the bit that tells us to use the new accounting function
@@ -2952,12 +2791,12 @@
 	 * (raid-z deflation).  If we have an older pool, this will not
 	 * be present.
 	 */
-	error = spa_dir_prop(spa, DMU_POOL_DEFLATE, &spa->spa_deflate, B_FALSE);
+	error = spa_dir_prop(spa, DMU_POOL_DEFLATE, &spa->spa_deflate);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
 	error = spa_dir_prop(spa, DMU_POOL_CREATION_VERSION,
-	    &spa->spa_creation_version, B_FALSE);
+	    &spa->spa_creation_version);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
@@ -2965,13 +2804,12 @@
 	 * Load the persistent error log.  If we have an older pool, this will
 	 * not be present.
 	 */
-	error = spa_dir_prop(spa, DMU_POOL_ERRLOG_LAST, &spa->spa_errlog_last,
-	    B_FALSE);
+	error = spa_dir_prop(spa, DMU_POOL_ERRLOG_LAST, &spa->spa_errlog_last);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
 	error = spa_dir_prop(spa, DMU_POOL_ERRLOG_SCRUB,
-	    &spa->spa_errlog_scrub, B_FALSE);
+	    &spa->spa_errlog_scrub);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
@@ -2979,7 +2817,7 @@
 	 * Load the history object.  If we have an older pool, this
 	 * will not be present.
 	 */
-	error = spa_dir_prop(spa, DMU_POOL_HISTORY, &spa->spa_history, B_FALSE);
+	error = spa_dir_prop(spa, DMU_POOL_HISTORY, &spa->spa_history);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
@@ -2992,13 +2830,11 @@
 
 	/* The sentinel is only available in the MOS config. */
 	nvlist_t *mos_config;
-	if (load_nvlist(spa, spa->spa_config_object, &mos_config) != 0) {
-		spa_load_failed(spa, "unable to retrieve MOS config");
+	if (load_nvlist(spa, spa->spa_config_object, &mos_config) != 0)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
 
 	error = spa_dir_prop(spa, DMU_POOL_VDEV_ZAP_MAP,
-	    &spa->spa_all_vdev_zaps, B_FALSE);
+	    &spa->spa_all_vdev_zaps);
 
 	if (error == ENOENT) {
 		VERIFY(!nvlist_exists(mos_config,
@@ -3022,50 +2858,7 @@
 	}
 	nvlist_free(mos_config);
 
-	spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);
-
-	error = spa_dir_prop(spa, DMU_POOL_PROPS, &spa->spa_pool_props_object,
-	    B_FALSE);
-	if (error && error != ENOENT)
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-
-	if (error == 0) {
-		uint64_t autoreplace;
-
-		spa_prop_find(spa, ZPOOL_PROP_BOOTFS, &spa->spa_bootfs);
-		spa_prop_find(spa, ZPOOL_PROP_AUTOREPLACE, &autoreplace);
-		spa_prop_find(spa, ZPOOL_PROP_DELEGATION, &spa->spa_delegation);
-		spa_prop_find(spa, ZPOOL_PROP_FAILUREMODE, &spa->spa_failmode);
-		spa_prop_find(spa, ZPOOL_PROP_AUTOEXPAND, &spa->spa_autoexpand);
-		spa_prop_find(spa, ZPOOL_PROP_DEDUPDITTO,
-		    &spa->spa_dedup_ditto);
-
-		spa->spa_autoreplace = (autoreplace != 0);
-	}
-
 	/*
-	 * If we are importing a pool with missing top-level vdevs,
-	 * we enforce that the pool doesn't panic or get suspended on
-	 * error since the likelihood of missing data is extremely high.
-	 */
-	if (spa->spa_missing_tvds > 0 &&
-	    spa->spa_failmode != ZIO_FAILURE_MODE_CONTINUE &&
-	    spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
-		spa_load_note(spa, "forcing failmode to 'continue' "
-		    "as some top level vdevs are missing");
-		spa->spa_failmode = ZIO_FAILURE_MODE_CONTINUE;
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_open_aux_vdevs(spa_t *spa, spa_import_type_t type)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
-	/*
 	 * If we're assembling the pool from the split-off vdevs of
 	 * an existing pool, we don't want to attach the spares & cache
 	 * devices.
@@ -3074,17 +2867,14 @@
 	/*
 	 * Load any hot spares for this pool.
 	 */
-	error = spa_dir_prop(spa, DMU_POOL_SPARES, &spa->spa_spares.sav_object,
-	    B_FALSE);
+	error = spa_dir_prop(spa, DMU_POOL_SPARES, &spa->spa_spares.sav_object);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 	if (error == 0 && type != SPA_IMPORT_ASSEMBLE) {
 		ASSERT(spa_version(spa) >= SPA_VERSION_SPARES);
 		if (load_nvlist(spa, spa->spa_spares.sav_object,
-		    &spa->spa_spares.sav_config) != 0) {
-			spa_load_failed(spa, "error loading spares nvlist");
+		    &spa->spa_spares.sav_config) != 0)
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-		}
 
 		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
 		spa_load_spares(spa);
@@ -3097,16 +2887,14 @@
 	 * Load any level 2 ARC devices for this pool.
 	 */
 	error = spa_dir_prop(spa, DMU_POOL_L2CACHE,
-	    &spa->spa_l2cache.sav_object, B_FALSE);
+	    &spa->spa_l2cache.sav_object);
 	if (error != 0 && error != ENOENT)
 		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 	if (error == 0 && type != SPA_IMPORT_ASSEMBLE) {
 		ASSERT(spa_version(spa) >= SPA_VERSION_L2CACHE);
 		if (load_nvlist(spa, spa->spa_l2cache.sav_object,
-		    &spa->spa_l2cache.sav_config) != 0) {
-			spa_load_failed(spa, "error loading l2cache nvlist");
+		    &spa->spa_l2cache.sav_config) != 0)
 			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-		}
 
 		spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
 		spa_load_l2cache(spa);
@@ -3115,15 +2903,106 @@
 		spa->spa_l2cache.sav_sync = B_TRUE;
 	}
 
-	return (0);
-}
+	mp = &spa->spa_meta_policy;
 
-static int
-spa_ld_load_vdev_metadata(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
+	spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);
+	spa->spa_hiwat = zpool_prop_default_numeric(ZPOOL_PROP_HIWATERMARK);
+	spa->spa_lowat = zpool_prop_default_numeric(ZPOOL_PROP_LOWATERMARK);
+	spa->spa_minwat = zpool_prop_default_numeric(ZPOOL_PROP_MINWATERMARK);
+	spa->spa_dedup_lo_best_effort =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUP_LO_BEST_EFFORT);
+	spa->spa_dedup_hi_best_effort =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUP_HI_BEST_EFFORT);
 
+	mp->spa_enable_meta_placement_selection =
+	    zpool_prop_default_numeric(ZPOOL_PROP_META_PLACEMENT);
+	mp->spa_sync_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_SYNC_TO_SPECIAL);
+	mp->spa_ddt_meta_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DDT_META_TO_METADEV);
+	mp->spa_zfs_meta_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_ZFS_META_TO_METADEV);
+	mp->spa_small_data_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_SMALL_DATA_TO_METADEV);
+	spa_set_ddt_classes(spa,
+	    zpool_prop_default_numeric(ZPOOL_PROP_DDT_DESEGREGATION));
+
+	spa->spa_resilver_prio =
+	    zpool_prop_default_numeric(ZPOOL_PROP_RESILVER_PRIO);
+	spa->spa_scrub_prio = zpool_prop_default_numeric(ZPOOL_PROP_SCRUB_PRIO);
+
+	error = spa_dir_prop(spa, DMU_POOL_PROPS, &spa->spa_pool_props_object);
+	if (error && error != ENOENT)
+		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+
+	if (error == 0) {
+		uint64_t autoreplace;
+		uint64_t val = 0;
+
+		spa_prop_find(spa, ZPOOL_PROP_BOOTFS, &spa->spa_bootfs);
+		spa_prop_find(spa, ZPOOL_PROP_AUTOREPLACE, &autoreplace);
+		spa_prop_find(spa, ZPOOL_PROP_DELEGATION, &spa->spa_delegation);
+		spa_prop_find(spa, ZPOOL_PROP_FAILUREMODE, &spa->spa_failmode);
+		spa_prop_find(spa, ZPOOL_PROP_AUTOEXPAND, &spa->spa_autoexpand);
+		spa_prop_find(spa, ZPOOL_PROP_BOOTSIZE, &spa->spa_bootsize);
+		spa_prop_find(spa, ZPOOL_PROP_DEDUPDITTO,
+		    &spa->spa_dedup_ditto);
+		spa_prop_find(spa, ZPOOL_PROP_FORCETRIM, &spa->spa_force_trim);
+
+		mutex_enter(&spa->spa_auto_trim_lock);
+		spa_prop_find(spa, ZPOOL_PROP_AUTOTRIM, &spa->spa_auto_trim);
+		if (spa->spa_auto_trim == SPA_AUTO_TRIM_ON)
+			spa_auto_trim_taskq_create(spa);
+		mutex_exit(&spa->spa_auto_trim_lock);
+
+		spa_prop_find(spa, ZPOOL_PROP_HIWATERMARK, &spa->spa_hiwat);
+		spa_prop_find(spa, ZPOOL_PROP_LOWATERMARK, &spa->spa_lowat);
+		spa_prop_find(spa, ZPOOL_PROP_MINWATERMARK, &spa->spa_minwat);
+		spa_prop_find(spa, ZPOOL_PROP_DEDUPMETA_DITTO,
+		    &spa->spa_ddt_meta_copies);
+		spa_prop_find(spa, ZPOOL_PROP_DDT_DESEGREGATION, &val);
+		spa_set_ddt_classes(spa, val);
+
+		spa_prop_find(spa, ZPOOL_PROP_RESILVER_PRIO,
+		    &spa->spa_resilver_prio);
+		spa_prop_find(spa, ZPOOL_PROP_SCRUB_PRIO,
+		    &spa->spa_scrub_prio);
+
+		spa_prop_find(spa, ZPOOL_PROP_DEDUP_BEST_EFFORT,
+		    &spa->spa_dedup_best_effort);
+		spa_prop_find(spa, ZPOOL_PROP_DEDUP_LO_BEST_EFFORT,
+		    &spa->spa_dedup_lo_best_effort);
+		spa_prop_find(spa, ZPOOL_PROP_DEDUP_HI_BEST_EFFORT,
+		    &spa->spa_dedup_hi_best_effort);
+
+		spa_prop_find(spa, ZPOOL_PROP_META_PLACEMENT,
+		    &mp->spa_enable_meta_placement_selection);
+		spa_prop_find(spa, ZPOOL_PROP_SYNC_TO_SPECIAL,
+		    &mp->spa_sync_to_special);
+		spa_prop_find(spa, ZPOOL_PROP_DDT_META_TO_METADEV,
+		    &mp->spa_ddt_meta_to_special);
+		spa_prop_find(spa, ZPOOL_PROP_ZFS_META_TO_METADEV,
+		    &mp->spa_zfs_meta_to_special);
+		spa_prop_find(spa, ZPOOL_PROP_SMALL_DATA_TO_METADEV,
+		    &mp->spa_small_data_to_special);
+
+		spa->spa_autoreplace = (autoreplace != 0);
+	}
+
+	error = spa_dir_prop(spa, DMU_POOL_COS_PROPS,
+	    &spa->spa_cos_props_object);
+	if (error == 0)
+		(void) spa_load_cos_props(spa);
+	error = spa_dir_prop(spa, DMU_POOL_VDEV_PROPS,
+	    &spa->spa_vdev_props_object);
+	if (error == 0)
+		(void) spa_load_vdev_props(spa);
+
+	(void) spa_dir_prop(spa, DMU_POOL_TRIM_START_TIME,
+	    &spa->spa_man_trim_start_time);
+	(void) spa_dir_prop(spa, DMU_POOL_TRIM_STOP_TIME,
+	    &spa->spa_man_trim_stop_time);
+
 	/*
 	 * If the 'autoreplace' property is set, then post a resource notifying
 	 * the ZFS DE that it should not issue any faults for unopenable
@@ -3131,7 +3010,7 @@
 	 * unopenable vdevs so that the normal autoreplace handler can take
 	 * over.
 	 */
-	if (spa->spa_autoreplace && spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
+	if (spa->spa_autoreplace && state != SPA_LOAD_TRYIMPORT) {
 		spa_check_removed(spa->spa_root_vdev);
 		/*
 		 * For the import case, this is done in spa_import(), because
@@ -3138,7 +3017,7 @@
 		 * at this point we're using the spare definitions from
 		 * the MOS config, not necessarily from the userland config.
 		 */
-		if (spa->spa_load_state != SPA_LOAD_IMPORT) {
+		if (state != SPA_LOAD_IMPORT) {
 			spa_aux_check_removed(&spa->spa_spares);
 			spa_aux_check_removed(&spa->spa_l2cache);
 		}
@@ -3145,325 +3024,62 @@
 	}
 
 	/*
-	 * Load the vdev metadata such as metaslabs, DTLs, spacemap object, etc.
+	 * Load the vdev state for all toplevel vdevs.
 	 */
-	error = vdev_load(rvd);
-	if (error != 0) {
-		spa_load_failed(spa, "vdev_load failed [error=%d]", error);
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, error));
-	}
+	vdev_load(rvd);
 
 	/*
-	 * Propagate the leaf DTLs we just loaded all the way up the vdev tree.
+	 * Propagate the leaf DTLs we just loaded all the way up the tree.
 	 */
 	spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
 	vdev_dtl_reassess(rvd, 0, 0, B_FALSE);
 	spa_config_exit(spa, SCL_ALL, FTAG);
 
-	return (0);
-}
-
-static int
-spa_ld_load_dedup_tables(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
-	error = ddt_load(spa);
-	if (error != 0) {
-		spa_load_failed(spa, "ddt_load failed [error=%d]", error);
-		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_verify_logs(spa_t *spa, spa_import_type_t type, char **ereport)
-{
-	vdev_t *rvd = spa->spa_root_vdev;
-
-	if (type != SPA_IMPORT_ASSEMBLE && spa_writeable(spa)) {
-		boolean_t missing = spa_check_logs(spa);
-		if (missing) {
-			if (spa->spa_missing_tvds != 0) {
-				spa_load_note(spa, "spa_check_logs failed "
-				    "so dropping the logs");
-			} else {
-				*ereport = FM_EREPORT_ZFS_LOG_REPLAY;
-				spa_load_failed(spa, "spa_check_logs failed");
-				return (spa_vdev_err(rvd, VDEV_AUX_BAD_LOG,
-				    ENXIO));
-			}
-		}
-	}
-
-	return (0);
-}
-
-static int
-spa_ld_verify_pool_data(spa_t *spa)
-{
-	int error = 0;
-	vdev_t *rvd = spa->spa_root_vdev;
-
 	/*
-	 * We've successfully opened the pool, verify that we're ready
-	 * to start pushing transactions.
+	 * Load the DDTs (dedup tables).
 	 */
-	if (spa->spa_load_state != SPA_LOAD_TRYIMPORT) {
-		error = spa_load_verify(spa);
-		if (error != 0) {
-			spa_load_failed(spa, "spa_load_verify failed "
-			    "[error=%d]", error);
-			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
-			    error));
-		}
-	}
-
-	return (0);
-}
-
-static void
-spa_ld_claim_log_blocks(spa_t *spa)
-{
-	dmu_tx_t *tx;
-	dsl_pool_t *dp = spa_get_dsl(spa);
-
-	/*
-	 * Claim log blocks that haven't been committed yet.
-	 * This must all happen in a single txg.
-	 * Note: spa_claim_max_txg is updated by spa_claim_notify(),
-	 * invoked from zil_claim_log_block()'s i/o done callback.
-	 * Price of rollback is that we abandon the log.
-	 */
-	spa->spa_claiming = B_TRUE;
-
-	tx = dmu_tx_create_assigned(dp, spa_first_txg(spa));
-	(void) dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
-	    zil_claim, tx, DS_FIND_CHILDREN);
-	dmu_tx_commit(tx);
-
-	spa->spa_claiming = B_FALSE;
-
-	spa_set_log_state(spa, SPA_LOG_GOOD);
-}
-
-static void
-spa_ld_check_for_config_update(spa_t *spa, uint64_t config_cache_txg,
-    boolean_t reloading)
-{
-	vdev_t *rvd = spa->spa_root_vdev;
-	int need_update = B_FALSE;
-
-	/*
-	 * If the config cache is stale, or we have uninitialized
-	 * metaslabs (see spa_vdev_add()), then update the config.
-	 *
-	 * If this is a verbatim import, trust the current
-	 * in-core spa_config and update the disk labels.
-	 */
-	if (reloading || config_cache_txg != spa->spa_config_txg ||
-	    spa->spa_load_state == SPA_LOAD_IMPORT ||
-	    spa->spa_load_state == SPA_LOAD_RECOVER ||
-	    (spa->spa_import_flags & ZFS_IMPORT_VERBATIM))
-		need_update = B_TRUE;
-
-	for (int 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);
-}
-
-static void
-spa_ld_prepare_for_reload(spa_t *spa)
-{
-	int mode = spa->spa_mode;
-	int async_suspended = spa->spa_async_suspended;
-
-	spa_unload(spa);
-	spa_deactivate(spa);
-	spa_activate(spa, mode);
-
-	/*
-	 * We save the value of spa_async_suspended as it gets reset to 0 by
-	 * spa_unload(). We want to restore it back to the original value before
-	 * returning as we might be calling spa_async_resume() later.
-	 */
-	spa->spa_async_suspended = async_suspended;
-}
-
-/*
- * Load an existing storage pool, using the config provided. This config
- * describes which vdevs are part of the pool and is later validated against
- * partial configs present in each vdev's label and an entire copy of the
- * config stored in the MOS.
- */
-static int
-spa_load_impl(spa_t *spa, spa_import_type_t type, char **ereport,
-    boolean_t reloading)
-{
-	int error = 0;
-	boolean_t missing_feat_write = B_FALSE;
-
-	ASSERT(MUTEX_HELD(&spa_namespace_lock));
-	ASSERT(spa->spa_config_source != SPA_CONFIG_SRC_NONE);
-
-	/*
-	 * Never trust the config that is provided unless we are assembling
-	 * a pool following a split.
-	 * This means don't trust blkptrs and the vdev tree in general. This
-	 * also effectively puts the spa in read-only mode since
-	 * spa_writeable() checks for spa_trust_config to be true.
-	 * We will later load a trusted config from the MOS.
-	 */
-	if (type != SPA_IMPORT_ASSEMBLE)
-		spa->spa_trust_config = B_FALSE;
-
-	if (reloading)
-		spa_load_note(spa, "RELOADING");
-	else
-		spa_load_note(spa, "LOADING");
-
-	/*
-	 * Parse the config provided to create a vdev tree.
-	 */
-	error = spa_ld_parse_config(spa, type);
+	error = ddt_load(spa);
 	if (error != 0)
-		return (error);
+		return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
-	/*
-	 * Now that we have the vdev tree, try to open each vdev. This involves
-	 * opening the underlying physical device, retrieving its geometry and
-	 * probing the vdev with a dummy I/O. The state of each vdev will be set
-	 * based on the success of those operations. After this we'll be ready
-	 * to read from the vdevs.
-	 */
-	error = spa_ld_open_vdevs(spa);
-	if (error != 0)
-		return (error);
+	spa_update_dspace(spa);
 
 	/*
-	 * Read the label of each vdev and make sure that the GUIDs stored
-	 * there match the GUIDs in the config provided.
-	 * If we're assembling a new pool that's been split off from an
-	 * existing pool, the labels haven't yet been updated so we skip
-	 * validation for now.
+	 * Validate the config, using the MOS config to fill in any
+	 * information which might be missing.  If we fail to validate
+	 * the config then declare the pool unfit for use. If we're
+	 * assembling a pool from a split, the log is not transferred
+	 * over.
 	 */
 	if (type != SPA_IMPORT_ASSEMBLE) {
-		error = spa_ld_validate_vdevs(spa);
-		if (error != 0)
-			return (error);
-	}
+		nvlist_t *nvconfig;
 
-	/*
-	 * Read vdev labels to find the best uberblock (i.e. latest, unless
-	 * spa_load_max_txg is set) and store it in spa_uberblock. We get the
-	 * list of features required to read blkptrs in the MOS from the vdev
-	 * label with the best uberblock and verify that our version of zfs
-	 * supports them all.
-	 */
-	error = spa_ld_select_uberblock(spa, type);
-	if (error != 0)
-		return (error);
+		if (load_nvlist(spa, spa->spa_config_object, &nvconfig) != 0)
+			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
-	/*
-	 * Pass that uberblock to the dsl_pool layer which will open the root
-	 * blkptr. This blkptr points to the latest version of the MOS and will
-	 * allow us to read its contents.
-	 */
-	error = spa_ld_open_rootbp(spa);
-	if (error != 0)
-		return (error);
+		if (!spa_config_valid(spa, nvconfig)) {
+			nvlist_free(nvconfig);
+			return (spa_vdev_err(rvd, VDEV_AUX_BAD_GUID_SUM,
+			    ENXIO));
+		}
+		nvlist_free(nvconfig);
 
-	/*
-	 * Retrieve the trusted config stored in the MOS and use it to create
-	 * a new, exact version of the vdev tree, then reopen all vdevs.
-	 */
-	error = spa_ld_load_trusted_config(spa, type, reloading);
-	if (error == EAGAIN) {
-		VERIFY(!reloading);
 		/*
-		 * Redo the loading process with the trusted config if it is
-		 * too different from the untrusted config.
+		 * Now that we've validated the config, check the state of the
+		 * root vdev.  If it can't be opened, it indicates one or
+		 * more toplevel vdevs are faulted.
 		 */
-		spa_ld_prepare_for_reload(spa);
-		return (spa_load_impl(spa, type, ereport, B_TRUE));
-	} else if (error != 0) {
-		return (error);
+		if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN)
+			return (SET_ERROR(ENXIO));
+
+		if (spa_writeable(spa) && spa_check_logs(spa)) {
+			*ereport = FM_EREPORT_ZFS_LOG_REPLAY;
+			return (spa_vdev_err(rvd, VDEV_AUX_BAD_LOG, ENXIO));
+		}
 	}
 
-	/*
-	 * Retrieve the mapping of indirect vdevs. Those vdevs were removed
-	 * from the pool and their contents were re-mapped to other vdevs. Note
-	 * that everything that we read before this step must have been
-	 * rewritten on concrete vdevs after the last device removal was
-	 * initiated. Otherwise we could be reading from indirect vdevs before
-	 * we have loaded their mappings.
-	 */
-	error = spa_ld_open_indirect_vdev_metadata(spa);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Retrieve the full list of active features from the MOS and check if
-	 * they are all supported.
-	 */
-	error = spa_ld_check_features(spa, &missing_feat_write);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Load several special directories from the MOS needed by the dsl_pool
-	 * layer.
-	 */
-	error = spa_ld_load_special_directories(spa);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Retrieve pool properties from the MOS.
-	 */
-	error = spa_ld_get_props(spa);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Retrieve the list of auxiliary devices - cache devices and spares -
-	 * and open them.
-	 */
-	error = spa_ld_open_aux_vdevs(spa, type);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Load the metadata for all vdevs. Also check if unopenable devices
-	 * should be autoreplaced.
-	 */
-	error = spa_ld_load_vdev_metadata(spa);
-	if (error != 0)
-		return (error);
-
-	error = spa_ld_load_dedup_tables(spa);
-	if (error != 0)
-		return (error);
-
-	/*
-	 * Verify the logs now to make sure we don't have any unexpected errors
-	 * when we claim log blocks later.
-	 */
-	error = spa_ld_verify_logs(spa, type, ereport);
-	if (error != 0)
-		return (error);
-
 	if (missing_feat_write) {
-		ASSERT(spa->spa_load_state == SPA_LOAD_TRYIMPORT);
+		ASSERT(state == SPA_LOAD_TRYIMPORT);
 
 		/*
 		 * At this point, we know that we can open the pool in
@@ -3470,45 +3086,45 @@
 		 * read-only mode but not read-write mode. We now have enough
 		 * information and can return to userland.
 		 */
-		return (spa_vdev_err(spa->spa_root_vdev, VDEV_AUX_UNSUP_FEAT,
-		    ENOTSUP));
+		return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT, ENOTSUP));
 	}
 
 	/*
-	 * Traverse the last txgs to make sure the pool was left off in a safe
-	 * state. When performing an extreme rewind, we verify the whole pool,
-	 * which can take a very long time.
+	 * We've successfully opened the pool, verify that we're ready
+	 * to start pushing transactions.
 	 */
-	error = spa_ld_verify_pool_data(spa);
-	if (error != 0)
-		return (error);
+	if (state != SPA_LOAD_TRYIMPORT) {
+		if (error = spa_load_verify(spa)) {
+			return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
+			    error));
+		}
+	}
 
-	/*
-	 * Calculate the deflated space for the pool. This must be done before
-	 * we write anything to the pool because we'd need to update the space
-	 * accounting using the deflated sizes.
-	 */
-	spa_update_dspace(spa);
-
-	/*
-	 * We have now retrieved all the information we needed to open the
-	 * pool. If we are importing the pool in read-write mode, a few
-	 * additional steps must be performed to finish the import.
-	 */
-	if (spa_writeable(spa) && (spa->spa_load_state == SPA_LOAD_RECOVER ||
+	if (spa_writeable(spa) && (state == SPA_LOAD_RECOVER ||
 	    spa->spa_load_max_txg == UINT64_MAX)) {
-		uint64_t config_cache_txg = spa->spa_config_txg;
+		dmu_tx_t *tx;
+		int need_update = B_FALSE;
+		dsl_pool_t *dp = spa_get_dsl(spa);
 
-		ASSERT(spa->spa_load_state != SPA_LOAD_TRYIMPORT);
+		ASSERT(state != SPA_LOAD_TRYIMPORT);
 
 		/*
-		 * Traverse the ZIL and claim all blocks.
+		 * Claim log blocks that haven't been committed yet.
+		 * This must all happen in a single txg.
+		 * Note: spa_claim_max_txg is updated by spa_claim_notify(),
+		 * invoked from zil_claim_log_block()'s i/o done callback.
+		 * Price of rollback is that we abandon the log.
 		 */
-		spa_ld_claim_log_blocks(spa);
+		spa->spa_claiming = B_TRUE;
 
-		/*
-		 * Kick-off the syncing thread.
-		 */
+		tx = dmu_tx_create_assigned(dp, spa_first_txg(spa));
+		(void) dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
+		    zil_claim, tx, DS_FIND_CHILDREN);
+		dmu_tx_commit(tx);
+
+		spa->spa_claiming = B_FALSE;
+
+		spa_set_log_state(spa, SPA_LOG_GOOD);
 		spa->spa_sync_on = B_TRUE;
 		txg_sync_start(spa->spa_dsl_pool);
 
@@ -3516,24 +3132,40 @@
 		 * Wait for all claims to sync.  We sync up to the highest
 		 * claimed log block birth time so that claimed log blocks
 		 * don't appear to be from the future.  spa_claim_max_txg
-		 * will have been set for us by ZIL traversal operations
-		 * performed above.
+		 * will have been set for us by either zil_check_log_chain()
+		 * (invoked from spa_check_logs()) or zil_claim() above.
 		 */
 		txg_wait_synced(spa->spa_dsl_pool, spa->spa_claim_max_txg);
 
 		/*
-		 * Check if we need to request an update of the config. On the
-		 * next sync, we would update the config stored in vdev labels
-		 * and the cachefile (by default /etc/zfs/zpool.cache).
+		 * If the config cache is stale, or we have uninitialized
+		 * metaslabs (see spa_vdev_add()), then update the config.
+		 *
+		 * If this is a verbatim import, trust the current
+		 * in-core spa_config and update the disk labels.
 		 */
-		spa_ld_check_for_config_update(spa, config_cache_txg,
-		    reloading);
+		if (config_cache_txg != spa->spa_config_txg ||
+		    state == SPA_LOAD_IMPORT ||
+		    state == SPA_LOAD_RECOVER ||
+		    (spa->spa_import_flags & ZFS_IMPORT_VERBATIM))
+			need_update = B_TRUE;
 
+		for (int 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);
+
+		/*
 		 * Check all DTLs to see if anything needs resilvering.
 		 */
 		if (!dsl_scan_resilvering(spa->spa_dsl_pool) &&
-		    vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL))
+		    vdev_resilver_needed(rvd, NULL, NULL))
 			spa_async_request(spa, SPA_ASYNC_RESILVER);
 
 		/*
@@ -3542,29 +3174,21 @@
 		 */
 		spa_history_log_version(spa, "open");
 
-		/*
-		 * Delete any inconsistent datasets.
-		 */
-		(void) dmu_objset_find(spa_name(spa),
-		    dsl_destroy_inconsistent, NULL, DS_FIND_CHILDREN);
+		dsl_destroy_inconsistent(spa_get_dsl(spa));
 
 		/*
 		 * Clean up any stale temporary dataset userrefs.
 		 */
 		dsl_pool_clean_tmp_userrefs(spa->spa_dsl_pool);
-
-		spa_restart_removal(spa);
-
-		spa_spawn_aux_threads(spa);
 	}
 
-	spa_load_note(spa, "LOADED");
+	spa_async_request(spa, SPA_ASYNC_L2CACHE_REBUILD);
 
 	return (0);
 }
 
 static int
-spa_load_retry(spa_t *spa, spa_load_state_t state)
+spa_load_retry(spa_t *spa, spa_load_state_t state, int mosconfig)
 {
 	int mode = spa->spa_mode;
 
@@ -3576,10 +3200,7 @@
 	spa_activate(spa, mode);
 	spa_async_suspend(spa);
 
-	spa_load_note(spa, "spa_load_retry: rewind, max txg: %llu",
-	    (u_longlong_t)spa->spa_load_max_txg);
-
-	return (spa_load(spa, state, SPA_IMPORT_EXISTING));
+	return (spa_load(spa, state, SPA_IMPORT_EXISTING, mosconfig));
 }
 
 /*
@@ -3590,8 +3211,8 @@
  * spa_load().
  */
 static int
-spa_load_best(spa_t *spa, spa_load_state_t state, uint64_t max_request,
-    int rewind_flags)
+spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
+    uint64_t max_request, int rewind_flags)
 {
 	nvlist_t *loadinfo = NULL;
 	nvlist_t *config = NULL;
@@ -3608,7 +3229,8 @@
 			spa->spa_extreme_rewind = B_TRUE;
 	}
 
-	load_error = rewind_error = spa_load(spa, state, SPA_IMPORT_EXISTING);
+	load_error = rewind_error = spa_load(spa, state, SPA_IMPORT_EXISTING,
+	    mosconfig);
 	if (load_error == 0)
 		return (0);
 
@@ -3649,7 +3271,7 @@
 	    spa->spa_uberblock.ub_txg <= spa->spa_load_max_txg) {
 		if (spa->spa_load_max_txg < safe_rewind_txg)
 			spa->spa_extreme_rewind = B_TRUE;
-		rewind_error = spa_load_retry(spa, state);
+		rewind_error = spa_load_retry(spa, state, mosconfig);
 	}
 
 	spa->spa_extreme_rewind = B_FALSE;
@@ -3696,6 +3318,7 @@
 	spa_load_state_t state = SPA_LOAD_OPEN;
 	int error;
 	int locked = B_FALSE;
+	boolean_t open_with_activation = B_FALSE;
 
 	*spapp = NULL;
 
@@ -3728,10 +3351,8 @@
 
 		if (state != SPA_LOAD_RECOVER)
 			spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
-		spa->spa_config_source = SPA_CONFIG_SRC_CACHEFILE;
 
-		zfs_dbgmsg("spa_open_common: opening %s", pool);
-		error = spa_load_best(spa, state, policy.zrp_txg,
+		error = spa_load_best(spa, state, B_FALSE, policy.zrp_txg,
 		    policy.zrp_request);
 
 		if (error == EBADF) {
@@ -3744,7 +3365,7 @@
 			 */
 			spa_unload(spa);
 			spa_deactivate(spa);
-			spa_write_cachefile(spa, B_TRUE, B_TRUE);
+			spa_config_sync(spa, B_TRUE, B_TRUE);
 			spa_remove(spa);
 			if (locked)
 				mutex_exit(&spa_namespace_lock);
@@ -3772,6 +3393,8 @@
 			*spapp = NULL;
 			return (error);
 		}
+
+		open_with_activation = B_TRUE;
 	}
 
 	spa_open_ref(spa, tag);
@@ -3795,6 +3418,9 @@
 		mutex_exit(&spa_namespace_lock);
 	}
 
+	if (open_with_activation)
+		wbc_activate(spa, B_FALSE);
+
 	*spapp = spa;
 
 	return (0);
@@ -4244,7 +3870,8 @@
 	nvlist_t **spares, **l2cache;
 	uint_t nspares, nl2cache;
 	uint64_t version, obj;
-	boolean_t has_features;
+	boolean_t has_features = B_FALSE, wbc_feature_exists = B_FALSE;
+	spa_meta_placement_t *mp;
 
 	/*
 	 * If this pool already exists, return failure.
@@ -4263,20 +3890,46 @@
 	spa = spa_add(pool, NULL, altroot);
 	spa_activate(spa, spa_mode_global);
 
-	if (props && (error = spa_prop_validate(spa, props))) {
-		spa_deactivate(spa);
-		spa_remove(spa);
-		mutex_exit(&spa_namespace_lock);
-		return (error);
-	}
+	if (props != NULL) {
+		nvpair_t *wbc_feature_nvp = NULL;
 
-	has_features = B_FALSE;
-	for (nvpair_t *elem = nvlist_next_nvpair(props, NULL);
-	    elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
-		if (zpool_prop_feature(nvpair_name(elem)))
-			has_features = B_TRUE;
+		for (nvpair_t *elem = nvlist_next_nvpair(props, NULL);
+		    elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
+			const char *propname = nvpair_name(elem);
+			if (zpool_prop_feature(propname)) {
+				spa_feature_t feature;
+				int err;
+				const char *fname = strchr(propname, '@') + 1;
+
+				err = zfeature_lookup_name(fname, &feature);
+				if (err == 0 && feature == SPA_FEATURE_WBC) {
+					wbc_feature_nvp = elem;
+					wbc_feature_exists = B_TRUE;
+				}
+
+				has_features = B_TRUE;
+			}
+		}
+
+		/*
+		 * We do not want to enabled feature@wbc if
+		 * this pool does not have special vdev.
+		 * At this stage we remove this feature from common list,
+		 * but later after check that special vdev available this
+		 * feature will be enabled
+		 */
+		if (wbc_feature_nvp != NULL)
+			fnvlist_remove_nvpair(props, wbc_feature_nvp);
+
+		if ((error = spa_prop_validate(spa, props)) != 0) {
+			spa_deactivate(spa);
+			spa_remove(spa);
+			mutex_exit(&spa_namespace_lock);
+			return (error);
+		}
 	}
 
+
 	if (has_features || nvlist_lookup_uint64(props,
 	    zpool_prop_to_name(ZPOOL_PROP_VERSION), &version) != 0) {
 		version = SPA_VERSION;
@@ -4288,9 +3941,6 @@
 	spa->spa_uberblock.ub_version = version;
 	spa->spa_ubsync = spa->spa_uberblock;
 	spa->spa_load_state = SPA_LOAD_CREATE;
-	spa->spa_removing_phys.sr_state = DSS_NONE;
-	spa->spa_removing_phys.sr_removing_vdev = -1;
-	spa->spa_removing_phys.sr_prev_indirect_vdev = -1;
 
 	/*
 	 * Create "The Godfather" zio to hold all async IOs
@@ -4434,6 +4084,8 @@
 	if (version >= SPA_VERSION_ZPOOL_HISTORY)
 		spa_history_create_obj(spa, tx);
 
+	mp = &spa->spa_meta_policy;
+
 	/*
 	 * Generate some random noise for salted checksums to operate on.
 	 */
@@ -4447,12 +4099,55 @@
 	spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);
 	spa->spa_failmode = zpool_prop_default_numeric(ZPOOL_PROP_FAILUREMODE);
 	spa->spa_autoexpand = zpool_prop_default_numeric(ZPOOL_PROP_AUTOEXPAND);
+	spa->spa_minwat = zpool_prop_default_numeric(ZPOOL_PROP_MINWATERMARK);
+	spa->spa_hiwat = zpool_prop_default_numeric(ZPOOL_PROP_HIWATERMARK);
+	spa->spa_lowat = zpool_prop_default_numeric(ZPOOL_PROP_LOWATERMARK);
+	spa->spa_ddt_meta_copies =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUPMETA_DITTO);
+	spa->spa_dedup_best_effort =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUP_BEST_EFFORT);
+	spa->spa_dedup_lo_best_effort =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUP_LO_BEST_EFFORT);
+	spa->spa_dedup_hi_best_effort =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DEDUP_HI_BEST_EFFORT);
+	spa->spa_force_trim = zpool_prop_default_numeric(ZPOOL_PROP_FORCETRIM);
 
+	spa->spa_resilver_prio =
+	    zpool_prop_default_numeric(ZPOOL_PROP_RESILVER_PRIO);
+	spa->spa_scrub_prio = zpool_prop_default_numeric(ZPOOL_PROP_SCRUB_PRIO);
+
+	mutex_enter(&spa->spa_auto_trim_lock);
+	spa->spa_auto_trim = zpool_prop_default_numeric(ZPOOL_PROP_AUTOTRIM);
+	if (spa->spa_auto_trim == SPA_AUTO_TRIM_ON)
+		spa_auto_trim_taskq_create(spa);
+	mutex_exit(&spa->spa_auto_trim_lock);
+
+	mp->spa_enable_meta_placement_selection =
+	    zpool_prop_default_numeric(ZPOOL_PROP_META_PLACEMENT);
+	mp->spa_sync_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_SYNC_TO_SPECIAL);
+	mp->spa_ddt_meta_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_DDT_META_TO_METADEV);
+	mp->spa_zfs_meta_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_ZFS_META_TO_METADEV);
+	mp->spa_small_data_to_special =
+	    zpool_prop_default_numeric(ZPOOL_PROP_SMALL_DATA_TO_METADEV);
+
+	spa_set_ddt_classes(spa, 0);
+
 	if (props != NULL) {
 		spa_configfile_set(spa, props, B_FALSE);
 		spa_sync_props(props, tx);
 	}
 
+	if (spa_has_special(spa)) {
+		spa_feature_enable(spa, SPA_FEATURE_META_DEVICES, tx);
+		spa_feature_incr(spa, SPA_FEATURE_META_DEVICES, tx);
+
+		if (wbc_feature_exists)
+			spa_feature_enable(spa, SPA_FEATURE_WBC, tx);
+	}
+
 	dmu_tx_commit(tx);
 
 	spa->spa_sync_on = B_TRUE;
@@ -4464,9 +4159,7 @@
 	 */
 	txg_wait_synced(spa->spa_dsl_pool, txg);
 
-	spa_spawn_aux_threads(spa);
-
-	spa_write_cachefile(spa, B_FALSE, B_TRUE);
+	spa_config_sync(spa, B_FALSE, B_TRUE);
 	spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_CREATE);
 
 	spa_history_log_version(spa, "create");
@@ -4481,9 +4174,57 @@
 
 	mutex_exit(&spa_namespace_lock);
 
+	wbc_activate(spa, B_TRUE);
+
 	return (0);
 }
 
+
+/*
+ * See if the pool has special tier, and if so, enable/activate
+ * the feature as needed. Activation is not reference counted.
+ */
+static void
+spa_check_special_feature(spa_t *spa)
+{
+	if (spa_has_special(spa)) {
+		nvlist_t *props = NULL;
+
+		if (!spa_feature_is_enabled(spa, SPA_FEATURE_META_DEVICES)) {
+			VERIFY(nvlist_alloc(&props, NV_UNIQUE_NAME, 0) == 0);
+			VERIFY(nvlist_add_uint64(props,
+			    FEATURE_META_DEVICES, 0) == 0);
+			VERIFY(spa_prop_set(spa, props) == 0);
+			nvlist_free(props);
+		}
+
+		if (!spa_feature_is_active(spa, SPA_FEATURE_META_DEVICES)) {
+			dmu_tx_t *tx =
+			    dmu_tx_create_dd(spa->spa_dsl_pool->dp_mos_dir);
+
+			VERIFY(dmu_tx_assign(tx, TXG_WAIT) == 0);
+			spa_feature_incr(spa, SPA_FEATURE_META_DEVICES, tx);
+			dmu_tx_commit(tx);
+		}
+	}
+}
+
+static void
+spa_special_feature_activate(void *arg, dmu_tx_t *tx)
+{
+	spa_t *spa = (spa_t *)arg;
+
+	if (spa_has_special(spa)) {
+		/* enable and activate as needed */
+		spa_feature_enable(spa, SPA_FEATURE_META_DEVICES, tx);
+		if (!spa_feature_is_active(spa, SPA_FEATURE_META_DEVICES)) {
+			spa_feature_incr(spa, SPA_FEATURE_META_DEVICES, tx);
+		}
+
+		spa_feature_enable(spa, SPA_FEATURE_WBC, tx);
+	}
+}
+
 #ifdef _KERNEL
 /*
  * Get the root pool information from the root disk, then import the root pool
@@ -4609,7 +4350,7 @@
 	VERIFY(nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG, &txg) == 0);
 
 	mutex_enter(&spa_namespace_lock);
-	if ((spa = spa_lookup(pname)) != NULL) {
+	if ((spa = spa_lookup(pname)) != NULL || spa_config_guid_exists(guid)) {
 		/*
 		 * Remove the existing root pool from the namespace so that we
 		 * can replace it with the correct config we just read in.
@@ -4620,9 +4361,6 @@
 	spa = spa_add(pname, config, NULL);
 	spa->spa_is_root = B_TRUE;
 	spa->spa_import_flags = ZFS_IMPORT_VERBATIM;
-	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION,
-	    &spa->spa_ubsync.ub_version) != 0)
-		spa->spa_ubsync.ub_version = SPA_VERSION_INITIAL;
 
 	/*
 	 * Build up a vdev tree based on the boot device's label config.
@@ -4706,12 +4444,16 @@
 	nvlist_t *nvroot;
 	nvlist_t **spares, **l2cache;
 	uint_t nspares, nl2cache;
+	uint64_t guid;
 
+	if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &guid) != 0)
+		return (SET_ERROR(EINVAL));
+
 	/*
 	 * If a pool with this name exists, return failure.
 	 */
 	mutex_enter(&spa_namespace_lock);
-	if (spa_lookup(pool) != NULL) {
+	if (spa_lookup(pool) != NULL || spa_config_guid_exists(guid)) {
 		mutex_exit(&spa_namespace_lock);
 		return (SET_ERROR(EEXIST));
 	}
@@ -4736,9 +4478,9 @@
 		if (props != NULL)
 			spa_configfile_set(spa, props, B_FALSE);
 
-		spa_write_cachefile(spa, B_FALSE, B_TRUE);
+		spa_config_sync(spa, B_FALSE, B_TRUE);
 		spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_IMPORT);
-		zfs_dbgmsg("spa_import: verbatim import of %s", pool);
+
 		mutex_exit(&spa_namespace_lock);
 		return (0);
 	}
@@ -4754,17 +4496,17 @@
 	if (policy.zrp_request & ZPOOL_DO_REWIND)
 		state = SPA_LOAD_RECOVER;
 
-	spa->spa_config_source = SPA_CONFIG_SRC_TRYIMPORT;
-
-	if (state != SPA_LOAD_RECOVER) {
+	/*
+	 * 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.
+	 */
+	if (state != SPA_LOAD_RECOVER)
 		spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
-		zfs_dbgmsg("spa_import: importing %s", pool);
-	} else {
-		zfs_dbgmsg("spa_import: importing %s, max_txg=%lld "
-		    "(RECOVERY MODE)", pool, (longlong_t)policy.zrp_txg);
-	}
-	error = spa_load_best(spa, state, policy.zrp_txg, policy.zrp_request);
 
+	error = spa_load_best(spa, state, B_TRUE, policy.zrp_txg,
+	    policy.zrp_request);
+
 	/*
 	 * Propagate anything learned while loading the pool and pass it
 	 * back to caller (i.e. rewind info, missing devices, etc).
@@ -4810,8 +4552,6 @@
 		return (error);
 	}
 
-	spa_async_resume(spa);
-
 	/*
 	 * Override any spares and level 2 cache devices as specified by
 	 * the user, as these may have correct device names/devids, etc.
@@ -4847,6 +4587,9 @@
 		spa->spa_l2cache.sav_sync = B_TRUE;
 	}
 
+	/* At this point, we can load spare props */
+	(void) spa_load_vdev_props(spa);
+
 	/*
 	 * Check for any removed devices.
 	 */
@@ -4863,11 +4606,22 @@
 	}
 
 	/*
+	 * Start async resume as late as possible to reduce I/O activity when
+	 * importing a pool. This will let any pending txgs (e.g. from scrub
+	 * or resilver) to complete quickly thereby reducing import times in
+	 * such cases.
+	 */
+	spa_async_resume(spa);
+
+	/*
 	 * It's possible that the pool was expanded while it was exported.
 	 * We kick off an async task to handle this for us.
 	 */
 	spa_async_request(spa, SPA_ASYNC_AUTOEXPAND);
 
+	/* Set/activate meta feature as needed */
+	if (!spa_writeable(spa))
+		spa_check_special_feature(spa);
 	spa_history_log_version(spa, "import");
 
 	spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_IMPORT);
@@ -4874,7 +4628,13 @@
 
 	mutex_exit(&spa_namespace_lock);
 
-	return (0);
+	if (!spa_writeable(spa))
+		return (0);
+
+	wbc_activate(spa, B_FALSE);
+
+	return (dsl_sync_task(spa->spa_name, NULL, spa_special_feature_activate,
+	    spa, 3, ZFS_SPACE_CHECK_RESERVED));
 }
 
 nvlist_t *
@@ -4881,11 +4641,10 @@
 spa_tryimport(nvlist_t *tryconfig)
 {
 	nvlist_t *config = NULL;
-	char *poolname, *cachefile;
+	char *poolname;
 	spa_t *spa;
 	uint64_t state;
 	int error;
-	zpool_rewind_policy_t policy;
 
 	if (nvlist_lookup_string(tryconfig, ZPOOL_CONFIG_POOL_NAME, &poolname))
 		return (NULL);
@@ -4901,30 +4660,12 @@
 	spa_activate(spa, FREAD);
 
 	/*
-	 * Rewind pool if a max txg was provided. Note that even though we
-	 * retrieve the complete rewind policy, only the rewind txg is relevant
-	 * for tryimport.
+	 * 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.
 	 */
-	zpool_get_rewind_policy(spa->spa_config, &policy);
-	if (policy.zrp_txg != UINT64_MAX) {
-		spa->spa_load_max_txg = policy.zrp_txg;
-		spa->spa_extreme_rewind = B_TRUE;
-		zfs_dbgmsg("spa_tryimport: importing %s, max_txg=%lld",
-		    poolname, (longlong_t)policy.zrp_txg);
-	} else {
-		zfs_dbgmsg("spa_tryimport: importing %s", poolname);
-	}
+	error = spa_load(spa, SPA_LOAD_TRYIMPORT, SPA_IMPORT_EXISTING, B_TRUE);
 
-	if (nvlist_lookup_string(tryconfig, ZPOOL_CONFIG_CACHEFILE, &cachefile)
-	    == 0) {
-		zfs_dbgmsg("spa_tryimport: using cachefile '%s'", cachefile);
-		spa->spa_config_source = SPA_CONFIG_SRC_CACHEFILE;
-	} else {
-		spa->spa_config_source = SPA_CONFIG_SRC_SCAN;
-	}
-
-	error = spa_load(spa, SPA_LOAD_TRYIMPORT, SPA_IMPORT_EXISTING);
-
 	/*
 	 * If 'tryconfig' was at least parsable, return the current config.
 	 */
@@ -4999,9 +4740,11 @@
  */
 static int
 spa_export_common(char *pool, int new_state, nvlist_t **oldconfig,
-    boolean_t force, boolean_t hardforce)
+    boolean_t force, boolean_t hardforce, boolean_t saveconfig)
 {
 	spa_t *spa;
+	zfs_autosnap_t *autosnap;
+	boolean_t wbcthr_stopped = B_FALSE;
 
 	if (oldconfig)
 		*oldconfig = NULL;
@@ -5016,11 +4759,27 @@
 	}
 
 	/*
-	 * Put a hold on the pool, drop the namespace lock, stop async tasks,
-	 * reacquire the namespace lock, and see if we can export.
+	 * Put a hold on the pool, drop the namespace lock, stop async tasks
+	 * and write cache thread, reacquire the namespace lock, and see
+	 * if we can export.
 	 */
 	spa_open_ref(spa, FTAG);
 	mutex_exit(&spa_namespace_lock);
+
+	autosnap = spa_get_autosnap(spa);
+	mutex_enter(&autosnap->autosnap_lock);
+
+	if (autosnap_has_children_zone(autosnap,
+	    spa_name(spa), B_TRUE)) {
+		mutex_exit(&autosnap->autosnap_lock);
+		spa_close(spa, FTAG);
+		return (EBUSY);
+	}
+
+	mutex_exit(&autosnap->autosnap_lock);
+
+	wbcthr_stopped = wbc_stop_thread(spa); /* stop write cache thread */
+	autosnap_destroyer_thread_stop(spa);
 	spa_async_suspend(spa);
 	mutex_enter(&spa_namespace_lock);
 	spa_close(spa, FTAG);
@@ -5047,6 +4806,9 @@
 		    new_state != POOL_STATE_UNINITIALIZED)) {
 			spa_async_resume(spa);
 			mutex_exit(&spa_namespace_lock);
+			if (wbcthr_stopped)
+				(void) wbc_start_thread(spa);
+			autosnap_destroyer_thread_start(spa);
 			return (SET_ERROR(EBUSY));
 		}
 
@@ -5060,6 +4822,9 @@
 		    spa_has_active_shared_spare(spa)) {
 			spa_async_resume(spa);
 			mutex_exit(&spa_namespace_lock);
+			if (wbcthr_stopped)
+				(void) wbc_start_thread(spa);
+			autosnap_destroyer_thread_start(spa);
 			return (SET_ERROR(EXDEV));
 		}
 
@@ -5081,6 +4846,8 @@
 	spa_event_notify(spa, NULL, NULL, ESC_ZFS_POOL_DESTROY);
 
 	if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
+		wbc_deactivate(spa);
+
 		spa_unload(spa);
 		spa_deactivate(spa);
 	}
@@ -5090,7 +4857,8 @@
 
 	if (new_state != POOL_STATE_UNINITIALIZED) {
 		if (!hardforce)
-			spa_write_cachefile(spa, B_TRUE, B_TRUE);
+			spa_config_sync(spa, !saveconfig, B_TRUE);
+
 		spa_remove(spa);
 	}
 	mutex_exit(&spa_namespace_lock);
@@ -5105,7 +4873,7 @@
 spa_destroy(char *pool)
 {
 	return (spa_export_common(pool, POOL_STATE_DESTROYED, NULL,
-	    B_FALSE, B_FALSE));
+	    B_FALSE, B_FALSE, B_FALSE));
 }
 
 /*
@@ -5113,10 +4881,10 @@
  */
 int
 spa_export(char *pool, nvlist_t **oldconfig, boolean_t force,
-    boolean_t hardforce)
+    boolean_t hardforce, boolean_t saveconfig)
 {
 	return (spa_export_common(pool, POOL_STATE_EXPORTED, oldconfig,
-	    force, hardforce));
+	    force, hardforce, saveconfig));
 }
 
 /*
@@ -5127,7 +4895,7 @@
 spa_reset(char *pool)
 {
 	return (spa_export_common(pool, POOL_STATE_UNINITIALIZED, NULL,
-	    B_FALSE, B_FALSE));
+	    B_FALSE, B_FALSE, B_FALSE));
 }
 
 /*
@@ -5148,6 +4916,7 @@
 	vdev_t *vd, *tvd;
 	nvlist_t **spares, **l2cache;
 	uint_t nspares, nl2cache;
+	dmu_tx_t *tx = NULL;
 
 	ASSERT(spa_writeable(spa));
 
@@ -5182,41 +4951,8 @@
 		return (spa_vdev_exit(spa, vd, txg, error));
 
 	/*
-	 * If we are in the middle of a device removal, we can only add
-	 * devices which match the existing devices in the pool.
-	 * If we are in the middle of a removal, or have some indirect
-	 * vdevs, we can not add raidz toplevels.
+	 * Transfer each new top-level vdev from vd to rvd.
 	 */
-	if (spa->spa_vdev_removal != NULL ||
-	    spa->spa_removing_phys.sr_prev_indirect_vdev != -1) {
-		for (int c = 0; c < vd->vdev_children; c++) {
-			tvd = vd->vdev_child[c];
-			if (spa->spa_vdev_removal != NULL &&
-			    tvd->vdev_ashift !=
-			    spa->spa_vdev_removal->svr_vdev->vdev_ashift) {
-				return (spa_vdev_exit(spa, vd, txg, EINVAL));
-			}
-			/* Fail if top level vdev is raidz */
-			if (tvd->vdev_ops == &vdev_raidz_ops) {
-				return (spa_vdev_exit(spa, vd, txg, EINVAL));
-			}
-			/*
-			 * Need the top level mirror to be
-			 * a mirror of leaf vdevs only
-			 */
-			if (tvd->vdev_ops == &vdev_mirror_ops) {
-				for (uint64_t cid = 0;
-				    cid < tvd->vdev_children; cid++) {
-					vdev_t *cvd = tvd->vdev_child[cid];
-					if (!cvd->vdev_ops->vdev_op_leaf) {
-						return (spa_vdev_exit(spa, vd,
-						    txg, EINVAL));
-					}
-				}
-			}
-		}
-	}
-
 	for (int c = 0; c < vd->vdev_children; c++) {
 
 		/*
@@ -5269,6 +5005,19 @@
 	spa_event_notify(spa, NULL, NULL, ESC_ZFS_VDEV_ADD);
 	mutex_exit(&spa_namespace_lock);
 
+	/*
+	 * "spa_last_synced_txg(spa) + 1" is used because:
+	 *   - spa_vdev_exit() calls txg_wait_synced() for "txg"
+	 *   - spa_config_update() calls txg_wait_synced() for
+	 *     "spa_last_synced_txg(spa) + 1"
+	 */
+	tx = dmu_tx_create_assigned(spa_get_dsl(spa),
+	    spa_last_synced_txg(spa) + 1);
+	spa_special_feature_activate(spa, tx);
+	dmu_tx_commit(tx);
+
+	wbc_activate(spa, B_FALSE);
+
 	return (0);
 }
 
@@ -5302,11 +5051,6 @@
 
 	oldvd = spa_lookup_by_guid(spa, guid, B_FALSE);
 
-	if (spa->spa_vdev_removal != NULL ||
-	    spa->spa_removing_phys.sr_prev_indirect_vdev != -1) {
-		return (spa_vdev_exit(spa, NULL, txg, EBUSY));
-	}
-
 	if (oldvd == NULL)
 		return (spa_vdev_exit(spa, NULL, txg, ENODEV));
 
@@ -5472,6 +5216,14 @@
 	spa_event_notify(spa, newvd, NULL, ESC_ZFS_VDEV_ATTACH);
 
 	/*
+	 * Check CoS property of the old vdev, add reference by new vdev
+	 */
+	if (oldvd->vdev_queue.vq_cos) {
+		cos_hold(oldvd->vdev_queue.vq_cos);
+		newvd->vdev_queue.vq_cos = oldvd->vdev_queue.vq_cos;
+	}
+
+	/*
 	 * Commit the config
 	 */
 	(void) spa_vdev_exit(spa, newrootvd, dtl_max_txg, 0);
@@ -5685,6 +5437,14 @@
 
 	spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE);
 
+	/*
+	 * Release the references to CoS descriptors if any
+	 */
+	if (vd->vdev_queue.vq_cos) {
+		cos_rele(vd->vdev_queue.vq_cos);
+		vd->vdev_queue.vq_cos = NULL;
+	}
+
 	/* hang on to the spa before we release the lock */
 	spa_open_ref(spa, FTAG);
 
@@ -5747,12 +5507,19 @@
 
 	ASSERT(spa_writeable(spa));
 
+	/*
+	 * split for pools with activated WBC
+	 * will be implemented in the next release
+	 */
+	if (spa_feature_is_active(spa, SPA_FEATURE_WBC))
+		return (SET_ERROR(ENOTSUP));
+
 	txg = spa_vdev_enter(spa);
 
 	/* clear the log and flush everything up to now */
 	activate_slog = spa_passivate_log(spa);
 	(void) spa_vdev_config_exit(spa, NULL, txg, 0, FTAG);
-	error = spa_reset_logs(spa);
+	error = spa_offline_log(spa);
 	txg = spa_vdev_config_enter(spa);
 
 	if (activate_slog)
@@ -5780,7 +5547,7 @@
 		vdev_t *vd = rvd->vdev_child[c];
 
 		/* don't count the holes & logs as children */
-		if (vd->vdev_islog || !vdev_is_concrete(vd)) {
+		if (vd->vdev_islog || vd->vdev_ishole) {
 			if (lastlog == 0)
 				lastlog = c;
 			continue;
@@ -5833,7 +5600,7 @@
 		/* make sure there's nothing stopping the split */
 		if (vml[c]->vdev_parent->vdev_ops != &vdev_mirror_ops ||
 		    vml[c]->vdev_islog ||
-		    !vdev_is_concrete(vml[c]) ||
+		    vml[c]->vdev_ishole ||
 		    vml[c]->vdev_isspare ||
 		    vml[c]->vdev_isl2cache ||
 		    !vdev_writeable(vml[c]) ||
@@ -5928,10 +5695,8 @@
 	spa_activate(newspa, spa_mode_global);
 	spa_async_suspend(newspa);
 
-	newspa->spa_config_source = SPA_CONFIG_SRC_SPLIT;
-
 	/* create the new pool from the disks of the original pool */
-	error = spa_load(newspa, SPA_LOAD_IMPORT, SPA_IMPORT_ASSEMBLE);
+	error = spa_load(newspa, SPA_LOAD_IMPORT, SPA_IMPORT_ASSEMBLE, B_TRUE);
 	if (error)
 		goto out;
 
@@ -5971,6 +5736,18 @@
 		dmu_tx_abort(tx);
 	for (c = 0; c < children; c++) {
 		if (vml[c] != NULL) {
+			vdev_t *tvd = vml[c]->vdev_top;
+
+			/*
+			 * Need to be sure the detachable VDEV is not
+			 * on any *other* txg's DTL list to prevent it
+			 * from being accessed after it's freed.
+			 */
+			for (int t = 0; t < TXG_SIZE; t++) {
+				(void) txg_list_remove_this(
+				    &tvd->vdev_dtl_list, vml[c], t);
+			}
+
 			vdev_split(vml[c]);
 			if (error == 0)
 				spa_history_log_internal(spa, "detach", tx,
@@ -5999,7 +5776,7 @@
 	/* if we're not going to mount the filesystems in userland, export */
 	if (exp)
 		error = spa_export_common(newname, POOL_STATE_EXPORTED, NULL,
-		    B_FALSE, B_FALSE);
+		    B_FALSE, B_FALSE, B_FALSE);
 
 	return (error);
 
@@ -6025,7 +5802,304 @@
 	return (error);
 }
 
+static nvlist_t *
+spa_nvlist_lookup_by_guid(nvlist_t **nvpp, int count, uint64_t target_guid)
+{
+	for (int i = 0; i < count; i++) {
+		uint64_t guid;
+
+		VERIFY(nvlist_lookup_uint64(nvpp[i], ZPOOL_CONFIG_GUID,
+		    &guid) == 0);
+
+		if (guid == target_guid)
+			return (nvpp[i]);
+	}
+
+	return (NULL);
+}
+
+static void
+spa_vdev_remove_aux(nvlist_t *config, char *name, nvlist_t **dev, int count,
+    nvlist_t *dev_to_remove)
+{
+	nvlist_t **newdev = NULL;
+
+	if (count > 1)
+		newdev = kmem_alloc((count - 1) * sizeof (void *), KM_SLEEP);
+
+	for (int i = 0, j = 0; i < count; i++) {
+		if (dev[i] == dev_to_remove)
+			continue;
+		VERIFY(nvlist_dup(dev[i], &newdev[j++], KM_SLEEP) == 0);
+	}
+
+	VERIFY(nvlist_remove(config, name, DATA_TYPE_NVLIST_ARRAY) == 0);
+	VERIFY(nvlist_add_nvlist_array(config, name, newdev, count - 1) == 0);
+
+	for (int i = 0; i < count - 1; i++)
+		nvlist_free(newdev[i]);
+
+	if (count > 1)
+		kmem_free(newdev, (count - 1) * sizeof (void *));
+}
+
 /*
+ * Evacuate the device.
+ */
+static int
+spa_vdev_remove_evacuate(spa_t *spa, vdev_t *vd)
+{
+	uint64_t txg;
+	int error = 0;
+
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
+	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);
+	ASSERT(vd == vd->vdev_top);
+
+	/*
+	 * Evacuate the device.  We don't hold the config lock as writer
+	 * since we need to do I/O but we do keep the
+	 * spa_namespace_lock held.  Once this completes the device
+	 * should no longer have any blocks allocated on it.
+	 */
+	if (vd->vdev_islog) {
+		if (vd->vdev_stat.vs_alloc != 0)
+			error = spa_offline_log(spa);
+	} else {
+		error = SET_ERROR(ENOTSUP);
+	}
+
+	if (error)
+		return (error);
+
+	/*
+	 * The evacuation succeeded.  Remove any remaining MOS metadata
+	 * associated with this vdev, and wait for these changes to sync.
+	 */
+	ASSERT0(vd->vdev_stat.vs_alloc);
+	txg = spa_vdev_config_enter(spa);
+	vd->vdev_removing = B_TRUE;
+	vdev_dirty_leaves(vd, VDD_DTL, txg);
+	vdev_config_dirty(vd);
+	spa_vdev_config_exit(spa, NULL, txg, 0, FTAG);
+
+	return (0);
+}
+
+/*
+ * Complete the removal by cleaning up the namespace.
+ */
+static void
+spa_vdev_remove_from_namespace(spa_t *spa, vdev_t *vd)
+{
+	vdev_t *rvd = spa->spa_root_vdev;
+	uint64_t id = vd->vdev_id;
+	boolean_t last_vdev = (id == (rvd->vdev_children - 1));
+
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
+	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
+	ASSERT(vd == vd->vdev_top);
+
+	/*
+	 * Only remove any devices which are empty.
+	 */
+	if (vd->vdev_stat.vs_alloc != 0)
+		return;
+
+	(void) vdev_label_init(vd, 0, VDEV_LABEL_REMOVE);
+
+	if (list_link_active(&vd->vdev_state_dirty_node))
+		vdev_state_clean(vd);
+	if (list_link_active(&vd->vdev_config_dirty_node))
+		vdev_config_clean(vd);
+
+	vdev_free(vd);
+
+	if (last_vdev) {
+		vdev_compact_children(rvd);
+	} else {
+		vd = vdev_alloc_common(spa, id, 0, &vdev_hole_ops);
+		vdev_add_child(rvd, vd);
+	}
+	vdev_config_dirty(rvd);
+
+	/*
+	 * Reassess the health of our root vdev.
+	 */
+	vdev_reopen(rvd);
+}
+
+/*
+ * Remove a device from the pool -
+ *
+ * Removing a device from the vdev namespace requires several steps
+ * and can take a significant amount of time.  As a result we use
+ * the spa_vdev_config_[enter/exit] functions which allow us to
+ * grab and release the spa_config_lock while still holding the namespace
+ * lock.  During each step the configuration is synced out.
+ *
+ * Currently, this supports removing only hot spares, slogs, level 2 ARC
+ * and special devices.
+ */
+int
+spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
+{
+	vdev_t *vd;
+	sysevent_t *ev = NULL;
+	metaslab_group_t *mg;
+	nvlist_t **spares, **l2cache, *nv;
+	uint64_t txg = 0;
+	uint_t nspares, nl2cache;
+	int error = 0;
+	boolean_t locked = MUTEX_HELD(&spa_namespace_lock);
+
+	ASSERT(spa_writeable(spa));
+
+	if (!locked)
+		txg = spa_vdev_enter(spa);
+
+	vd = spa_lookup_by_guid(spa, guid, B_FALSE);
+
+	if (spa->spa_spares.sav_vdevs != NULL &&
+	    nvlist_lookup_nvlist_array(spa->spa_spares.sav_config,
+	    ZPOOL_CONFIG_SPARES, &spares, &nspares) == 0 &&
+	    (nv = spa_nvlist_lookup_by_guid(spares, nspares, guid)) != NULL) {
+		/*
+		 * Only remove the hot spare if it's not currently in use
+		 * in this pool.
+		 */
+		if (vd == NULL || unspare) {
+			if (vd == NULL)
+				vd = spa_lookup_by_guid(spa, guid, B_TRUE);
+
+			/*
+			 * Release the references to CoS descriptors if any
+			 */
+			if (vd != NULL && vd->vdev_queue.vq_cos) {
+				cos_rele(vd->vdev_queue.vq_cos);
+				vd->vdev_queue.vq_cos = NULL;
+			}
+
+			ev = spa_event_create(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE_AUX);
+			spa_vdev_remove_aux(spa->spa_spares.sav_config,
+			    ZPOOL_CONFIG_SPARES, spares, nspares, nv);
+			spa_load_spares(spa);
+			spa->spa_spares.sav_sync = B_TRUE;
+		} else {
+			error = SET_ERROR(EBUSY);
+		}
+	} else if (spa->spa_l2cache.sav_vdevs != NULL &&
+	    nvlist_lookup_nvlist_array(spa->spa_l2cache.sav_config,
+	    ZPOOL_CONFIG_L2CACHE, &l2cache, &nl2cache) == 0 &&
+	    (nv = spa_nvlist_lookup_by_guid(l2cache, nl2cache, guid)) != NULL) {
+		/*
+		 * Cache devices can always be removed.
+		 */
+		if (vd == NULL)
+			vd = spa_lookup_by_guid(spa, guid, B_TRUE);
+		/*
+		 * Release the references to CoS descriptors if any
+		 */
+		if (vd != NULL && vd->vdev_queue.vq_cos) {
+			cos_rele(vd->vdev_queue.vq_cos);
+			vd->vdev_queue.vq_cos = NULL;
+		}
+
+		ev = spa_event_create(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE_AUX);
+		spa_vdev_remove_aux(spa->spa_l2cache.sav_config,
+		    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache, nv);
+		spa_load_l2cache(spa);
+		spa->spa_l2cache.sav_sync = B_TRUE;
+	} else if (vd != NULL && vd->vdev_islog) {
+		ASSERT(!locked);
+
+		if (vd != vd->vdev_top)
+			return (spa_vdev_exit(spa, NULL, txg, SET_ERROR(ENOTSUP)));
+
+		mg = vd->vdev_mg;
+
+		/*
+		 * Stop allocating from this vdev.
+		 */
+		metaslab_group_passivate(mg);
+
+		/*
+		 * Wait for the youngest allocations and frees to sync,
+		 * and then wait for the deferral of those frees to finish.
+		 */
+		spa_vdev_config_exit(spa, NULL,
+		    txg + TXG_CONCURRENT_STATES + TXG_DEFER_SIZE, 0, FTAG);
+
+		/*
+		 * Attempt to evacuate the vdev.
+		 */
+		error = spa_vdev_remove_evacuate(spa, vd);
+
+		txg = spa_vdev_config_enter(spa);
+
+		/*
+		 * If we couldn't evacuate the vdev, unwind.
+		 */
+		if (error) {
+			metaslab_group_activate(mg);
+			return (spa_vdev_exit(spa, NULL, txg, error));
+		}
+
+		/*
+		 * Release the references to CoS descriptors if any
+		 */
+		if (vd->vdev_queue.vq_cos) {
+			cos_rele(vd->vdev_queue.vq_cos);
+			vd->vdev_queue.vq_cos = NULL;
+		}
+
+		ev = spa_event_create(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE_DEV);
+
+		/*
+		 * Clean up the vdev namespace.
+		 */
+		ev = spa_event_create(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE_DEV);
+		spa_vdev_remove_from_namespace(spa, vd);
+
+	} else if (vd != NULL && vdev_is_special(vd)) {
+		ASSERT(!locked);
+
+		if (vd != vd->vdev_top)
+			return (spa_vdev_exit(spa, NULL, txg, SET_ERROR(ENOTSUP)));
+
+		error = spa_special_vdev_remove(spa, vd, &txg);
+		if (error == 0) {
+			ev = spa_event_create(spa, vd, NULL, ESC_ZFS_VDEV_REMOVE_DEV);
+			spa_vdev_remove_from_namespace(spa, vd);
+
+			/*
+			 * User sees this field as 'enablespecial'
+			 * pool-level property
+			 */
+			spa->spa_usesc = B_FALSE;
+		}
+	} else if (vd != NULL) {
+		/*
+		 * Normal vdevs cannot be removed (yet).
+		 */
+		error = SET_ERROR(ENOTSUP);
+	} else {
+		/*
+		 * There is no vdev of any kind with the specified guid.
+		 */
+		error = SET_ERROR(ENOENT);
+	}
+
+	if (!locked)
+		error = spa_vdev_exit(spa, NULL, txg, error);
+
+	if (ev)
+		spa_event_notify_impl(ev);
+
+	return (error);
+}
+
+/*
  * Find any device that's done replacing, or a vdev marked 'unspare' that's
  * currently spared, so we can detach it.
  */
@@ -6062,6 +6136,7 @@
 
 	/*
 	 * Check for a completed resilver with the 'unspare' flag set.
+	 * Also potentially update faulted state.
 	 */
 	if (vd->vdev_ops == &vdev_spare_ops) {
 		vdev_t *first = vd->vdev_child[0];
@@ -6083,6 +6158,8 @@
 		    !vdev_dtl_required(oldvd))
 			return (oldvd);
 
+		vdev_propagate_state(vd);
+
 		/*
 		 * If there are more than two spares attached to a disk,
 		 * and those spares are not required, then we want to
@@ -6143,58 +6220,6 @@
 }
 
 /*
- * Update the stored path or FRU for this vdev.
- */
-int
-spa_vdev_set_common(spa_t *spa, uint64_t guid, const char *value,
-    boolean_t ispath)
-{
-	vdev_t *vd;
-	boolean_t sync = B_FALSE;
-
-	ASSERT(spa_writeable(spa));
-
-	spa_vdev_state_enter(spa, SCL_ALL);
-
-	if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
-		return (spa_vdev_state_exit(spa, NULL, ENOENT));
-
-	if (!vd->vdev_ops->vdev_op_leaf)
-		return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
-
-	if (ispath) {
-		if (strcmp(value, vd->vdev_path) != 0) {
-			spa_strfree(vd->vdev_path);
-			vd->vdev_path = spa_strdup(value);
-			sync = B_TRUE;
-		}
-	} else {
-		if (vd->vdev_fru == NULL) {
-			vd->vdev_fru = spa_strdup(value);
-			sync = B_TRUE;
-		} else if (strcmp(value, vd->vdev_fru) != 0) {
-			spa_strfree(vd->vdev_fru);
-			vd->vdev_fru = spa_strdup(value);
-			sync = B_TRUE;
-		}
-	}
-
-	return (spa_vdev_state_exit(spa, sync ? vd : NULL, 0));
-}
-
-int
-spa_vdev_setpath(spa_t *spa, uint64_t guid, const char *newpath)
-{
-	return (spa_vdev_set_common(spa, guid, newpath, B_TRUE));
-}
-
-int
-spa_vdev_setfru(spa_t *spa, uint64_t guid, const char *newfru)
-{
-	return (spa_vdev_set_common(spa, guid, newfru, B_FALSE));
-}
-
-/*
  * ==========================================================================
  * SPA Scanning
  * ==========================================================================
@@ -6391,6 +6416,18 @@
 		dsl_resilver_restart(spa->spa_dsl_pool, 0);
 
 	/*
+	 * Kick off L2 cache rebuilding.
+	 */
+	if (tasks & SPA_ASYNC_L2CACHE_REBUILD)
+		l2arc_spa_rebuild_start(spa);
+
+	if (tasks & SPA_ASYNC_MAN_TRIM_TASKQ_DESTROY) {
+		mutex_enter(&spa->spa_man_trim_lock);
+		spa_man_trim_taskq_destroy(spa);
+		mutex_exit(&spa->spa_man_trim_lock);
+	}
+
+	/*
 	 * Let the world know that we're done.
 	 */
 	mutex_enter(&spa->spa_async_lock);
@@ -6408,12 +6445,6 @@
 	while (spa->spa_async_thread != NULL)
 		cv_wait(&spa->spa_async_cv, &spa->spa_async_lock);
 	mutex_exit(&spa->spa_async_lock);
-
-	spa_vdev_remove_suspend(spa);
-
-	zthr_t *condense_thread = spa->spa_condense_zthr;
-	if (condense_thread != NULL && zthr_isrunning(condense_thread))
-		VERIFY0(zthr_cancel(condense_thread));
 }
 
 void
@@ -6423,11 +6454,6 @@
 	ASSERT(spa->spa_async_suspended != 0);
 	spa->spa_async_suspended--;
 	mutex_exit(&spa->spa_async_lock);
-	spa_restart_removal(spa);
-
-	zthr_t *condense_thread = spa->spa_condense_zthr;
-	if (condense_thread != NULL && !zthr_isrunning(condense_thread))
-		zthr_resume(condense_thread);
 }
 
 static boolean_t
@@ -6472,6 +6498,15 @@
 	mutex_exit(&spa->spa_async_lock);
 }
 
+void
+spa_async_unrequest(spa_t *spa, int task)
+{
+	zfs_dbgmsg("spa=%s async unrequest task=%u", spa->spa_name, task);
+	mutex_enter(&spa->spa_async_lock);
+	spa->spa_async_tasks &= ~task;
+	mutex_exit(&spa->spa_async_lock);
+}
+
 /*
  * ==========================================================================
  * SPA syncing routines
@@ -6760,6 +6795,7 @@
 {
 	nvlist_t *nvp = arg;
 	spa_t *spa = dmu_tx_pool(tx)->dp_spa;
+	spa_meta_placement_t *mp = &spa->spa_meta_policy;
 	objset_t *mos = spa->spa_meta_objset;
 	nvpair_t *elem = NULL;
 
@@ -6774,7 +6810,7 @@
 		spa_feature_t fid;
 
 		switch (prop = zpool_name_to_prop(nvpair_name(elem))) {
-		case ZPOOL_PROP_INVAL:
+		case ZPROP_INVAL:
 			/*
 			 * We checked this earlier in spa_prop_validate().
 			 */
@@ -6872,6 +6908,18 @@
 			case ZPOOL_PROP_DELEGATION:
 				spa->spa_delegation = intval;
 				break;
+			case ZPOOL_PROP_DDT_DESEGREGATION:
+				spa_set_ddt_classes(spa, intval);
+				break;
+			case ZPOOL_PROP_DEDUP_BEST_EFFORT:
+				spa->spa_dedup_best_effort = intval;
+				break;
+			case ZPOOL_PROP_DEDUP_LO_BEST_EFFORT:
+				spa->spa_dedup_lo_best_effort = intval;
+				break;
+			case ZPOOL_PROP_DEDUP_HI_BEST_EFFORT:
+				spa->spa_dedup_hi_best_effort = intval;
+				break;
 			case ZPOOL_PROP_BOOTFS:
 				spa->spa_bootfs = intval;
 				break;
@@ -6878,6 +6926,21 @@
 			case ZPOOL_PROP_FAILUREMODE:
 				spa->spa_failmode = intval;
 				break;
+			case ZPOOL_PROP_FORCETRIM:
+				spa->spa_force_trim = intval;
+				break;
+			case ZPOOL_PROP_AUTOTRIM:
+				mutex_enter(&spa->spa_auto_trim_lock);
+				if (intval != spa->spa_auto_trim) {
+					spa->spa_auto_trim = intval;
+					if (intval != 0)
+						spa_auto_trim_taskq_create(spa);
+					else
+						spa_auto_trim_taskq_destroy(
+						    spa);
+				}
+				mutex_exit(&spa->spa_auto_trim_lock);
+				break;
 			case ZPOOL_PROP_AUTOEXPAND:
 				spa->spa_autoexpand = intval;
 				if (tx->tx_txg != TXG_INITIAL)
@@ -6887,6 +6950,40 @@
 			case ZPOOL_PROP_DEDUPDITTO:
 				spa->spa_dedup_ditto = intval;
 				break;
+			case ZPOOL_PROP_MINWATERMARK:
+				spa->spa_minwat = intval;
+				break;
+			case ZPOOL_PROP_LOWATERMARK:
+				spa->spa_lowat = intval;
+				break;
+			case ZPOOL_PROP_HIWATERMARK:
+				spa->spa_hiwat = intval;
+				break;
+			case ZPOOL_PROP_DEDUPMETA_DITTO:
+				spa->spa_ddt_meta_copies = intval;
+				break;
+			case ZPOOL_PROP_META_PLACEMENT:
+				mp->spa_enable_meta_placement_selection =
+				    intval;
+				break;
+			case ZPOOL_PROP_SYNC_TO_SPECIAL:
+				mp->spa_sync_to_special = intval;
+				break;
+			case ZPOOL_PROP_DDT_META_TO_METADEV:
+				mp->spa_ddt_meta_to_special = intval;
+				break;
+			case ZPOOL_PROP_ZFS_META_TO_METADEV:
+				mp->spa_zfs_meta_to_special = intval;
+				break;
+			case ZPOOL_PROP_SMALL_DATA_TO_METADEV:
+				mp->spa_small_data_to_special = intval;
+				break;
+			case ZPOOL_PROP_RESILVER_PRIO:
+				spa->spa_resilver_prio = intval;
+				break;
+			case ZPOOL_PROP_SCRUB_PRIO:
+				spa->spa_scrub_prio = intval;
+				break;
 			default:
 				break;
 			}
@@ -6972,36 +7069,45 @@
 }
 
 static void
-vdev_indirect_state_sync_verify(vdev_t *vd)
+spa_initialize_alloc_trees(spa_t *spa, uint32_t max_queue_depth,
+    uint64_t queue_depth_total)
 {
-	vdev_indirect_mapping_t *vim = vd->vdev_indirect_mapping;
-	vdev_indirect_births_t *vib = vd->vdev_indirect_births;
+	vdev_t *rvd = spa->spa_root_vdev;
+	boolean_t dva_throttle_enabled = zio_dva_throttle_enabled;
+	metaslab_class_t *mcs[2] = {
+		spa_normal_class(spa),
+		spa_special_class(spa)
+	};
+	size_t mcs_len = sizeof (mcs) / sizeof (metaslab_class_t *);
 
-	if (vd->vdev_ops == &vdev_indirect_ops) {
-		ASSERT(vim != NULL);
-		ASSERT(vib != NULL);
-	}
+	for (size_t i = 0; i < mcs_len; i++) {
+		metaslab_class_t *mc = mcs[i];
 
-	if (vdev_obsolete_sm_object(vd) != 0) {
-		ASSERT(vd->vdev_obsolete_sm != NULL);
-		ASSERT(vd->vdev_removing ||
-		    vd->vdev_ops == &vdev_indirect_ops);
-		ASSERT(vdev_indirect_mapping_num_entries(vim) > 0);
-		ASSERT(vdev_indirect_mapping_bytes_mapped(vim) > 0);
+		ASSERT0(refcount_count(&mc->mc_alloc_slots));
+		mc->mc_alloc_max_slots = queue_depth_total;
+		mc->mc_alloc_throttle_enabled = dva_throttle_enabled;
 
-		ASSERT3U(vdev_obsolete_sm_object(vd), ==,
-		    space_map_object(vd->vdev_obsolete_sm));
-		ASSERT3U(vdev_indirect_mapping_bytes_mapped(vim), >=,
-		    space_map_allocated(vd->vdev_obsolete_sm));
+		ASSERT3U(mc->mc_alloc_max_slots, <=,
+		    max_queue_depth * rvd->vdev_children);
 	}
-	ASSERT(vd->vdev_obsolete_segments != NULL);
+}
 
-	/*
-	 * Since frees / remaps to an indirect vdev can only
-	 * happen in syncing context, the obsolete segments
-	 * tree must be empty when we start syncing.
-	 */
-	ASSERT0(range_tree_space(vd->vdev_obsolete_segments));
+static void
+spa_check_alloc_trees(spa_t *spa)
+{
+	metaslab_class_t *mcs[2] = {
+		spa_normal_class(spa),
+		spa_special_class(spa)
+	};
+	size_t mcs_len = sizeof (mcs) / sizeof (metaslab_class_t *);
+
+	for (size_t i = 0; i < mcs_len; i++) {
+		metaslab_class_t *mc = mcs[i];
+
+		mutex_enter(&mc->mc_alloc_lock);
+		VERIFY0(avl_numnodes(&mc->mc_alloc_tree));
+		mutex_exit(&mc->mc_alloc_lock);
+	}
 }
 
 /*
@@ -7024,13 +7130,6 @@
 	VERIFY(spa_writeable(spa));
 
 	/*
-	 * Wait for i/os issued in open context that need to complete
-	 * before this txg syncs.
-	 */
-	VERIFY0(zio_wait(spa->spa_txg_zio[txg & TXG_MASK]));
-	spa->spa_txg_zio[txg & TXG_MASK] = zio_root(spa, NULL, NULL, 0);
-
-	/*
 	 * Lock out configuration changes.
 	 */
 	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
@@ -7038,11 +7137,20 @@
 	spa->spa_syncing_txg = txg;
 	spa->spa_sync_pass = 0;
 
-	mutex_enter(&spa->spa_alloc_lock);
-	VERIFY0(avl_numnodes(&spa->spa_alloc_tree));
-	mutex_exit(&spa->spa_alloc_lock);
+	spa_check_alloc_trees(spa);
 
 	/*
+	 * Another pool management task might be currently preventing
+	 * from starting and the current txg sync was invoked on its behalf,
+	 * so be prepared to postpone autotrim processing.
+	 */
+	if (mutex_tryenter(&spa->spa_auto_trim_lock)) {
+		if (spa->spa_auto_trim == SPA_AUTO_TRIM_ON)
+			spa_auto_trim(spa, txg);
+		mutex_exit(&spa->spa_auto_trim_lock);
+	}
+
+	/*
 	 * If there are any pending vdev state changes, convert them
 	 * into config changes that go out with this transaction group.
 	 */
@@ -7117,27 +7225,26 @@
 		mg->mg_max_alloc_queue_depth = max_queue_depth;
 		queue_depth_total += mg->mg_max_alloc_queue_depth;
 	}
-	metaslab_class_t *mc = spa_normal_class(spa);
-	ASSERT0(refcount_count(&mc->mc_alloc_slots));
-	mc->mc_alloc_max_slots = queue_depth_total;
-	mc->mc_alloc_throttle_enabled = zio_dva_throttle_enabled;
 
-	ASSERT3U(mc->mc_alloc_max_slots, <=,
-	    max_queue_depth * rvd->vdev_children);
+	spa_initialize_alloc_trees(spa, max_queue_depth,
+	    queue_depth_total);
 
-	for (int c = 0; c < rvd->vdev_children; c++) {
-		vdev_t *vd = rvd->vdev_child[c];
-		vdev_indirect_state_sync_verify(vd);
-
-		if (vdev_indirect_should_condense(vd)) {
-			spa_condense_indirect_start_sync(vd, tx);
-			break;
-		}
-	}
-
 	/*
 	 * Iterate to convergence.
 	 */
+
+	zfs_autosnap_t *autosnap = spa_get_autosnap(dp->dp_spa);
+	mutex_enter(&autosnap->autosnap_lock);
+
+	autosnap_zone_t *zone = list_head(&autosnap->autosnap_zones);
+	while (zone != NULL) {
+		zone->created = B_FALSE;
+		zone->dirty = B_FALSE;
+		zone = list_next(&autosnap->autosnap_zones, zone);
+	}
+
+	mutex_exit(&autosnap->autosnap_lock);
+
 	do {
 		int pass = ++spa->spa_sync_pass;
 
@@ -7164,11 +7271,7 @@
 		ddt_sync(spa, txg);
 		dsl_scan_sync(dp, tx);
 
-		if (spa->spa_vdev_removal != NULL)
-			svr_sync(spa, tx);
-
-		while ((vd = txg_list_remove(&spa->spa_vdev_txg_list, txg))
-		    != NULL)
+		while (vd = txg_list_remove(&spa->spa_vdev_txg_list, txg))
 			vdev_sync(vd, txg);
 
 		if (pass == 1) {
@@ -7220,10 +7323,6 @@
 		    all_vdev_zap_entry_count);
 	}
 
-	if (spa->spa_vdev_removal != NULL) {
-		ASSERT0(spa->spa_vdev_removal->svr_bytes_done[txg & TXG_MASK]);
-	}
-
 	/*
 	 * Rewrite the vdev configuration (which includes the uberblock)
 	 * to commit the transaction group.
@@ -7241,7 +7340,7 @@
 		spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
 
 		if (list_is_empty(&spa->spa_config_dirty_list)) {
-			vdev_t *svd[SPA_SYNC_MIN_VDEVS];
+			vdev_t *svd[SPA_DVAS_PER_BP];
 			int svdcount = 0;
 			int children = rvd->vdev_children;
 			int c0 = spa_get_random(children);
@@ -7248,11 +7347,10 @@
 
 			for (int c = 0; c < children; c++) {
 				vd = rvd->vdev_child[(c0 + c) % children];
-				if (vd->vdev_ms_array == 0 || vd->vdev_islog ||
-				    !vdev_is_concrete(vd))
+				if (vd->vdev_ms_array == 0 || vd->vdev_islog)
 					continue;
 				svd[svdcount++] = vd;
-				if (svdcount == SPA_SYNC_MIN_VDEVS)
+				if (svdcount == SPA_DVAS_PER_BP)
 					break;
 			}
 			error = vdev_config_sync(svd, svdcount, txg);
@@ -7293,9 +7391,7 @@
 
 	dsl_pool_sync_done(dp, txg);
 
-	mutex_enter(&spa->spa_alloc_lock);
-	VERIFY0(avl_numnodes(&spa->spa_alloc_tree));
-	mutex_exit(&spa->spa_alloc_lock);
+	spa_check_alloc_trees(spa);
 
 	/*
 	 * Update usable space statistics.
@@ -7304,7 +7400,7 @@
 		vdev_sync_done(vd, txg);
 
 	spa_update_dspace(spa);
-
+	spa_update_latency(spa);
 	/*
 	 * It had better be the case that we didn't dirty anything
 	 * since vdev_config_sync().
@@ -7315,6 +7411,8 @@
 
 	spa->spa_sync_pass = 0;
 
+	spa_check_special(spa);
+
 	/*
 	 * Update the last synced uberblock here. We want to do this at
 	 * the end of spa_sync() so that consumers of spa_last_synced_txg()
@@ -7387,9 +7485,12 @@
 		spa_close(spa, FTAG);
 
 		if (spa->spa_state != POOL_STATE_UNINITIALIZED) {
+			wbc_deactivate(spa);
+
 			spa_unload(spa);
 			spa_deactivate(spa);
 		}
+
 		spa_remove(spa);
 	}
 	mutex_exit(&spa_namespace_lock);
@@ -7485,7 +7586,14 @@
 	return (B_FALSE);
 }
 
-sysevent_t *
+/*
+ * Post a sysevent corresponding to the given event.  The 'name' must be one of
+ * the event definitions in sys/sysevent/eventdefs.h.  The payload will be
+ * filled in from the spa and (optionally) the vdev.  This doesn't do anything
+ * in the userland libzpool, as we don't want consumers to misinterpret ztest
+ * or zdb as real changes.
+ */
+static sysevent_t *
 spa_event_create(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl, const char *name)
 {
 	sysevent_t		*ev = NULL;
@@ -7507,7 +7615,7 @@
 	if (sysevent_add_attr(&attr, ZFS_EV_POOL_GUID, &value, SE_SLEEP) != 0)
 		goto done;
 
-	if (vd) {
+	if (vd != NULL) {
 		value.value_type = SE_DATA_TYPE_UINT64;
 		value.value.sv_uint64 = vd->vdev_guid;
 		if (sysevent_add_attr(&attr, ZFS_EV_VDEV_GUID, &value,
@@ -7539,10 +7647,12 @@
 	return (ev);
 }
 
-void
-spa_event_post(sysevent_t *ev)
+static void
+spa_event_post(void *arg)
 {
 #ifdef _KERNEL
+	sysevent_t *ev = (sysevent_t *)arg;
+
 	sysevent_id_t		eid;
 
 	(void) log_sysevent(ev, SE_SLEEP, &eid);
@@ -7550,23 +7660,296 @@
 #endif
 }
 
+/*
+ * Dispatch event notifications to the taskq such that the corresponding
+ * sysevents are queued with no spa locks held
+ */
+taskq_t *spa_sysevent_taskq;
+
+static void
+spa_event_notify_impl(sysevent_t *ev)
+{
+	if (taskq_dispatch(spa_sysevent_taskq, spa_event_post,
+	    ev, TQ_NOSLEEP) == NULL) {
+		/*
+		 * These are management sysevents; as much as it is
+		 * unpleasant to drop these due to syseventd not being able
+		 * to keep up, perhaps due to resource shortages, we are not
+		 * going to sleep here and risk locking up the pool sync
+		 * process; notify admin of problems
+		 */
+		cmn_err(CE_NOTE, "Could not dispatch sysevent nofitication "
+		    "for %s, please check state of syseventd\n",
+		    sysevent_get_subclass_name(ev));
+
+		sysevent_free(ev);
+
+		return;
+	}
+}
+
 void
-spa_event_discard(sysevent_t *ev)
+spa_event_notify(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl, const char *name)
 {
-#ifdef _KERNEL
-	sysevent_free(ev);
-#endif
+	spa_event_notify_impl(spa_event_create(spa, vd, hist_nvl, name));
 }
 
 /*
- * Post a sysevent corresponding to the given event.  The 'name' must be one of
- * the event definitions in sys/sysevent/eventdefs.h.  The payload will be
- * filled in from the spa and (optionally) the vdev and history nvl.  This
- * doesn't do anything in the userland libzpool, as we don't want consumers to
- * misinterpret ztest or zdb as real changes.
+ * Dispatches all auto-trim processing to all top-level vdevs. This is
+ * called from spa_sync once every txg.
  */
+static void
+spa_auto_trim(spa_t *spa, uint64_t txg)
+{
+	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER) == SCL_CONFIG);
+	ASSERT(MUTEX_HELD(&spa->spa_auto_trim_lock));
+	ASSERT(spa->spa_auto_trim_taskq != NULL);
+
+	for (uint64_t i = 0; i < spa->spa_root_vdev->vdev_children; i++) {
+		vdev_trim_info_t *vti = kmem_zalloc(sizeof (*vti), KM_SLEEP);
+		vti->vti_vdev = spa->spa_root_vdev->vdev_child[i];
+		vti->vti_txg = txg;
+		vti->vti_done_cb = (void (*)(void *))spa_vdev_auto_trim_done;
+		vti->vti_done_arg = spa;
+		(void) taskq_dispatch(spa->spa_auto_trim_taskq,
+		    (void (*)(void *))vdev_auto_trim, vti, TQ_SLEEP);
+		spa->spa_num_auto_trimming++;
+	}
+}
+
+/*
+ * Performs the sync update of the MOS pool directory's trim start/stop values.
+ */
+static void
+spa_trim_update_time_sync(void *arg, dmu_tx_t *tx)
+{
+	spa_t *spa = arg;
+	VERIFY0(zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_TRIM_START_TIME, sizeof (uint64_t), 1,
+	    &spa->spa_man_trim_start_time, tx));
+	VERIFY0(zap_update(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+	    DMU_POOL_TRIM_STOP_TIME, sizeof (uint64_t), 1,
+	    &spa->spa_man_trim_stop_time, tx));
+}
+
+/*
+ * Updates the in-core and on-disk manual TRIM operation start/stop time.
+ * Passing UINT64_MAX for either start_time or stop_time means that no
+ * update to that value should be recorded.
+ */
+static dmu_tx_t *
+spa_trim_update_time(spa_t *spa, uint64_t start_time, uint64_t stop_time)
+{
+	int err;
+	dmu_tx_t *tx;
+
+	ASSERT(MUTEX_HELD(&spa->spa_man_trim_lock));
+	if (start_time != UINT64_MAX)
+		spa->spa_man_trim_start_time = start_time;
+	if (stop_time != UINT64_MAX)
+		spa->spa_man_trim_stop_time = stop_time;
+	tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err) {
+		dmu_tx_abort(tx);
+		return (NULL);
+	}
+	dsl_sync_task_nowait(spa_get_dsl(spa), spa_trim_update_time_sync,
+	    spa, 1, ZFS_SPACE_CHECK_RESERVED, tx);
+
+	return (tx);
+}
+
+/*
+ * Initiates an manual TRIM of the whole pool. This kicks off individual
+ * TRIM tasks for each top-level vdev, which then pass over all of the free
+ * space in all of the vdev's metaslabs and issues TRIM commands for that
+ * space to the underlying vdevs.
+ */
+extern void
+spa_man_trim(spa_t *spa, uint64_t rate)
+{
+	dmu_tx_t *time_update_tx;
+
+	mutex_enter(&spa->spa_man_trim_lock);
+
+	if (rate != 0)
+		spa->spa_man_trim_rate = MAX(rate, spa_min_trim_rate(spa));
+	else
+		spa->spa_man_trim_rate = 0;
+
+	if (spa->spa_num_man_trimming) {
+		/*
+		 * TRIM is already ongoing. Wake up all sleeping vdev trim
+		 * threads because the trim rate might have changed above.
+		 */
+		cv_broadcast(&spa->spa_man_trim_update_cv);
+		mutex_exit(&spa->spa_man_trim_lock);
+		return;
+	}
+	spa_man_trim_taskq_create(spa);
+	spa->spa_man_trim_stop = B_FALSE;
+
+	spa_event_notify(spa, NULL, NULL, ESC_ZFS_TRIM_START);
+	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+	for (uint64_t i = 0; i < spa->spa_root_vdev->vdev_children; i++) {
+		vdev_t *vd = spa->spa_root_vdev->vdev_child[i];
+		vdev_trim_info_t *vti = kmem_zalloc(sizeof (*vti), KM_SLEEP);
+		vti->vti_vdev = vd;
+		vti->vti_done_cb = (void (*)(void *))spa_vdev_man_trim_done;
+		vti->vti_done_arg = spa;
+		spa->spa_num_man_trimming++;
+
+		vd->vdev_trim_prog = 0;
+		(void) taskq_dispatch(spa->spa_man_trim_taskq,
+		    (void (*)(void *))vdev_man_trim, vti, TQ_SLEEP);
+	}
+	spa_config_exit(spa, SCL_CONFIG, FTAG);
+	time_update_tx = spa_trim_update_time(spa, gethrestime_sec(), 0);
+	mutex_exit(&spa->spa_man_trim_lock);
+	/* mustn't hold spa_man_trim_lock to prevent deadlock /w syncing ctx */
+	if (time_update_tx != NULL)
+		dmu_tx_commit(time_update_tx);
+}
+
+/*
+ * Orders a manual TRIM operation to stop and returns immediately.
+ */
+extern void
+spa_man_trim_stop(spa_t *spa)
+{
+	boolean_t held = MUTEX_HELD(&spa->spa_man_trim_lock);
+	if (!held)
+		mutex_enter(&spa->spa_man_trim_lock);
+	spa->spa_man_trim_stop = B_TRUE;
+	cv_broadcast(&spa->spa_man_trim_update_cv);
+	if (!held)
+		mutex_exit(&spa->spa_man_trim_lock);
+}
+
+/*
+ * Orders a manual TRIM operation to stop and waits for both manual and
+ * automatic TRIM to complete. By holding both the spa_man_trim_lock and
+ * the spa_auto_trim_lock, the caller can guarantee that after this
+ * function returns, no new TRIM operations can be initiated in parallel.
+ */
 void
-spa_event_notify(spa_t *spa, vdev_t *vd, nvlist_t *hist_nvl, const char *name)
+spa_trim_stop_wait(spa_t *spa)
 {
-	spa_event_post(spa_event_create(spa, vd, hist_nvl, name));
+	ASSERT(MUTEX_HELD(&spa->spa_man_trim_lock));
+	ASSERT(MUTEX_HELD(&spa->spa_auto_trim_lock));
+	spa->spa_man_trim_stop = B_TRUE;
+	cv_broadcast(&spa->spa_man_trim_update_cv);
+	while (spa->spa_num_man_trimming > 0)
+		cv_wait(&spa->spa_man_trim_done_cv, &spa->spa_man_trim_lock);
+	while (spa->spa_num_auto_trimming > 0)
+		cv_wait(&spa->spa_auto_trim_done_cv, &spa->spa_auto_trim_lock);
+}
+
+/*
+ * Returns manual TRIM progress. Progress is indicated by four return values:
+ * 1) prog: the number of bytes of space on the pool in total that manual
+ *	TRIM has already passed (regardless if the space is allocated or not).
+ *	Completion of the operation is indicated when either the returned value
+ *	is zero, or when the returned value is equal to the sum of the sizes of
+ *	all top-level vdevs.
+ * 2) rate: the trim rate in bytes per second. A value of zero indicates that
+ *	trim progresses as fast as possible.
+ * 3) start_time: the UNIXTIME of when the last manual TRIM operation was
+ *	started. If no manual trim was ever initiated on the pool, this is
+ *	zero.
+ * 4) stop_time: the UNIXTIME of when the last manual TRIM operation has
+ *	stopped on the pool. If a trim was started (start_time != 0), but has
+ *	not yet completed, stop_time will be zero. If a trim is NOT currently
+ *	ongoing and start_time is non-zero, this indicates that the previously
+ *	initiated TRIM operation was interrupted.
+ */
+extern void
+spa_get_trim_prog(spa_t *spa, uint64_t *prog, uint64_t *rate,
+    uint64_t *start_time, uint64_t *stop_time)
+{
+	uint64_t total = 0;
+	vdev_t *root_vd = spa->spa_root_vdev;
+
+	ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));
+	mutex_enter(&spa->spa_man_trim_lock);
+	if (spa->spa_num_man_trimming > 0) {
+		for (uint64_t i = 0; i < root_vd->vdev_children; i++) {
+			total += root_vd->vdev_child[i]->vdev_trim_prog;
+		}
+	}
+	*prog = total;
+	*rate = spa->spa_man_trim_rate;
+	*start_time = spa->spa_man_trim_start_time;
+	*stop_time = spa->spa_man_trim_stop_time;
+	mutex_exit(&spa->spa_man_trim_lock);
+}
+
+/*
+ * Callback when a vdev_man_trim has finished on a single top-level vdev.
+ */
+static void
+spa_vdev_man_trim_done(spa_t *spa)
+{
+	dmu_tx_t *time_update_tx = NULL;
+
+	mutex_enter(&spa->spa_man_trim_lock);
+	ASSERT(spa->spa_num_man_trimming > 0);
+	spa->spa_num_man_trimming--;
+	if (spa->spa_num_man_trimming == 0) {
+		/* if we were interrupted, leave stop_time at zero */
+		if (!spa->spa_man_trim_stop)
+			time_update_tx = spa_trim_update_time(spa, UINT64_MAX,
+			    gethrestime_sec());
+		spa_event_notify(spa, NULL, NULL, ESC_ZFS_TRIM_FINISH);
+		spa_async_request(spa, SPA_ASYNC_MAN_TRIM_TASKQ_DESTROY);
+		cv_broadcast(&spa->spa_man_trim_done_cv);
+	}
+	mutex_exit(&spa->spa_man_trim_lock);
+
+	if (time_update_tx != NULL)
+		dmu_tx_commit(time_update_tx);
+}
+
+/*
+ * Called from vdev_auto_trim when a vdev has completed its auto-trim
+ * processing.
+ */
+static void
+spa_vdev_auto_trim_done(spa_t *spa)
+{
+	mutex_enter(&spa->spa_auto_trim_lock);
+	ASSERT(spa->spa_num_auto_trimming > 0);
+	spa->spa_num_auto_trimming--;
+	if (spa->spa_num_auto_trimming == 0)
+		cv_broadcast(&spa->spa_auto_trim_done_cv);
+	mutex_exit(&spa->spa_auto_trim_lock);
+}
+
+/*
+ * Determines the minimum sensible rate at which a manual TRIM can be
+ * performed on a given spa and returns it. Since we perform TRIM in
+ * metaslab-sized increments, we'll just let the longest step between
+ * metaslab TRIMs be 100s (random number, really). Thus, on a typical
+ * 200-metaslab vdev, the longest TRIM should take is about 5.5 hours.
+ * It *can* take longer if the device is really slow respond to
+ * zio_trim() commands or it contains more than 200 metaslabs, or
+ * metaslab sizes vary widely between top-level vdevs.
+ */
+static uint64_t
+spa_min_trim_rate(spa_t *spa)
+{
+	uint64_t smallest_ms_sz = UINT64_MAX;
+
+	/* find the smallest metaslab */
+	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+	for (uint64_t i = 0; i < spa->spa_root_vdev->vdev_children; i++) {
+		smallest_ms_sz = MIN(smallest_ms_sz,
+		    spa->spa_root_vdev->vdev_child[i]->vdev_ms[0]->ms_size);
+	}
+	spa_config_exit(spa, SCL_CONFIG, FTAG);
+	VERIFY(smallest_ms_sz != 0);
+
+	/* minimum TRIM rate is 1/100th of the smallest metaslab size */
+	return (smallest_ms_sz / 100);
 }
