Update core ZFS code from build 121 to build 141.
[zfs.git] / module / zfs / spa.c
index d7ed23e..d7c5de0 100644 (file)
@@ -20,8 +20,7 @@
  */
 
 /*
- * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 /*
 #include <sys/spa_impl.h>
 #include <sys/zio.h>
 #include <sys/zio_checksum.h>
-#include <sys/zio_compress.h>
 #include <sys/dmu.h>
 #include <sys/dmu_tx.h>
 #include <sys/zap.h>
 #include <sys/zil.h>
+#include <sys/ddt.h>
 #include <sys/vdev_impl.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/arc.h>
 #include <sys/callb.h>
 #include <sys/systeminfo.h>
-#include <sys/sunddi.h>
 #include <sys/spa_boot.h>
 #include <sys/zfs_ioctl.h>
+#include <sys/dsl_scan.h>
 
 #ifdef _KERNEL
+#include <sys/bootprops.h>
+#include <sys/callb.h>
+#include <sys/cpupart.h>
+#include <sys/pool.h>
+#include <sys/sysdc.h>
 #include <sys/zone.h>
 #endif /* _KERNEL */
 
 #include "zfs_prop.h"
 #include "zfs_comutil.h"
 
-enum zti_modes {
+typedef enum zti_modes {
        zti_mode_fixed,                 /* value is # of threads (min 1) */
        zti_mode_online_percent,        /* value is % of online CPUs */
-       zti_mode_tune,                  /* fill from zio_taskq_tune_* */
+       zti_mode_batch,                 /* cpu-intensive; value is ignored */
+       zti_mode_null,                  /* don't create a taskq */
        zti_nmodes
-};
+} zti_modes_t;
 
-#define        ZTI_THREAD_FIX(n)       { zti_mode_fixed, (n) }
-#define        ZTI_THREAD_PCT(n)       { zti_mode_online_percent, (n) }
-#define        ZTI_THREAD_TUNE         { zti_mode_tune, 0 }
+#define        ZTI_FIX(n)      { zti_mode_fixed, (n) }
+#define        ZTI_PCT(n)      { zti_mode_online_percent, (n) }
+#define        ZTI_BATCH       { zti_mode_batch, 0 }
+#define        ZTI_NULL        { zti_mode_null, 0 }
 
-#define        ZTI_THREAD_ONE          ZTI_THREAD_FIX(1)
+#define        ZTI_ONE         ZTI_FIX(1)
 
 typedef struct zio_taskq_info {
-       const char *zti_name;
-       struct {
-               enum zti_modes zti_mode;
-               uint_t zti_value;
-       } zti_nthreads[ZIO_TASKQ_TYPES];
+       enum zti_modes zti_mode;
+       uint_t zti_value;
 } zio_taskq_info_t;
 
 static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
-                               "issue",                "intr"
+       "issue", "issue_high", "intr", "intr_high"
 };
 
-const zio_taskq_info_t zio_taskqs[ZIO_TYPES] = {
-       /*                      ISSUE                   INTR            */
-       { "spa_zio_null",       { ZTI_THREAD_ONE,       ZTI_THREAD_ONE } },
-       { "spa_zio_read",       { ZTI_THREAD_FIX(8),    ZTI_THREAD_TUNE } },
-       { "spa_zio_write",      { ZTI_THREAD_TUNE,      ZTI_THREAD_FIX(8) } },
-       { "spa_zio_free",       { ZTI_THREAD_ONE,       ZTI_THREAD_ONE } },
-       { "spa_zio_claim",      { ZTI_THREAD_ONE,       ZTI_THREAD_ONE } },
-       { "spa_zio_ioctl",      { ZTI_THREAD_ONE,       ZTI_THREAD_ONE } },
+/*
+ * Define the taskq threads for the following I/O types:
+ *     NULL, READ, WRITE, FREE, CLAIM, and IOCTL
+ */
+const zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
+       /* ISSUE        ISSUE_HIGH      INTR            INTR_HIGH */
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL },
+       { ZTI_FIX(8),   ZTI_NULL,       ZTI_BATCH,      ZTI_NULL },
+       { ZTI_BATCH,    ZTI_FIX(5),     ZTI_FIX(8),     ZTI_FIX(5) },
+       { ZTI_FIX(100), ZTI_NULL,       ZTI_ONE,        ZTI_NULL },
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL },
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL },
 };
 
-enum zti_modes zio_taskq_tune_mode = zti_mode_online_percent;
-uint_t zio_taskq_tune_value = 80;      /* #threads = 80% of # online CPUs */
-
-static void spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx);
+static dsl_syncfunc_t spa_sync_props;
 static boolean_t spa_has_active_shared_spare(spa_t *spa);
+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);
+
+uint_t         zio_taskq_batch_pct = 100;      /* 1 thread per cpu in pset */
+id_t           zio_taskq_psrset_bind = PS_NONE;
+boolean_t      zio_taskq_sysdc = B_TRUE;       /* use SDC scheduling class */
+uint_t         zio_taskq_basedc = 80;          /* base duty cycle */
+
+boolean_t      spa_create_process = B_TRUE;    /* no process ==> no sysdc */
+
+/*
+ * 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"
 
 /*
  * ==========================================================================
@@ -144,7 +165,7 @@ static void
 spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
 {
        uint64_t size;
-       uint64_t used;
+       uint64_t alloc;
        uint64_t cap, version;
        zprop_source_t src = ZPROP_SRC_NONE;
        spa_config_dirent_t *dp;
@@ -152,17 +173,20 @@ spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
        ASSERT(MUTEX_HELD(&spa->spa_props_lock));
 
        if (spa->spa_root_vdev != NULL) {
-               size = spa_get_space(spa);
-               used = spa_get_alloc(spa);
+               alloc = metaslab_class_get_alloc(spa_normal_class(spa));
+               size = metaslab_class_get_space(spa_normal_class(spa));
                spa_prop_add_list(*nvp, ZPOOL_PROP_NAME, spa_name(spa), 0, src);
                spa_prop_add_list(*nvp, ZPOOL_PROP_SIZE, NULL, size, src);
-               spa_prop_add_list(*nvp, ZPOOL_PROP_USED, NULL, used, src);
-               spa_prop_add_list(*nvp, ZPOOL_PROP_AVAILABLE, NULL,
-                   size - used, src);
+               spa_prop_add_list(*nvp, ZPOOL_PROP_ALLOCATED, NULL, alloc, src);
+               spa_prop_add_list(*nvp, ZPOOL_PROP_FREE, NULL,
+                   size - alloc, src);
 
-               cap = (size == 0) ? 0 : (used * 100 / size);
+               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_DEDUPRATIO, NULL,
+                   ddt_get_pool_dedup_ratio(spa), src);
+
                spa_prop_add_list(*nvp, ZPOOL_PROP_HEALTH, NULL,
                    spa->spa_root_vdev->vdev_state, src);
 
@@ -197,9 +221,9 @@ spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
 int
 spa_prop_get(spa_t *spa, nvlist_t **nvp)
 {
+       objset_t *mos = spa->spa_meta_objset;
        zap_cursor_t zc;
        zap_attribute_t za;
-       objset_t *mos = spa->spa_meta_objset;
        int err;
 
        VERIFY(nvlist_alloc(nvp, NV_UNIQUE_NAME, KM_SLEEP) == 0);
@@ -212,7 +236,7 @@ spa_prop_get(spa_t *spa, nvlist_t **nvp)
        spa_prop_get_config(spa, nvp);
 
        /* If no pool property object, no more prop to get. */
-       if (spa->spa_pool_props_object == 0) {
+       if (mos == NULL || spa->spa_pool_props_object == 0) {
                mutex_exit(&spa->spa_props_lock);
                return (0);
        }
@@ -371,12 +395,14 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
                                        break;
                                }
 
-                               if (error = dmu_objset_open(strval, DMU_OST_ZFS,
-                                   DS_MODE_USER | DS_MODE_READONLY, &os))
+                               if (error = dmu_objset_hold(strval, FTAG, &os))
                                        break;
 
-                               /* We don't support gzip bootable datasets */
-                               if ((error = dsl_prop_get_integer(strval,
+                               /* Must be ZPL and not gzip compressed. */
+
+                               if (dmu_objset_type(os) != DMU_OST_ZFS) {
+                                       error = ENOTSUP;
+                               } else if ((error = dsl_prop_get_integer(strval,
                                    zfs_prop_to_name(ZFS_PROP_COMPRESSION),
                                    &compress, NULL)) == 0 &&
                                    !BOOTFS_COMPRESS_VALID(compress)) {
@@ -384,7 +410,7 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
                                } else {
                                        objnum = dmu_objset_id(os);
                                }
-                               dmu_objset_close(os);
+                               dmu_objset_rele(os, FTAG);
                        }
                        break;
 
@@ -432,6 +458,16 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
                            strcmp(slash, "/..") == 0)
                                error = EINVAL;
                        break;
+
+               case ZPOOL_PROP_DEDUPDITTO:
+                       if (spa_version(spa) < SPA_VERSION_DEDUP)
+                               error = ENOTSUP;
+                       else
+                               error = nvpair_value_uint64(elem, &intval);
+                       if (error == 0 &&
+                           intval != 0 && intval < ZIO_DEDUPDITTO_MIN)
+                               error = EINVAL;
+                       break;
                }
 
                if (error)
@@ -565,63 +601,185 @@ spa_get_errlists(spa_t *spa, avl_tree_t *last, avl_tree_t *scrub)
            offsetof(spa_error_entry_t, se_avl));
 }
 
-/*
- * Activate an uninitialized pool.
- */
-static void
-spa_activate(spa_t *spa, int mode)
+static taskq_t *
+spa_taskq_create(spa_t *spa, const char *name, enum zti_modes mode,
+    uint_t value)
 {
-       ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);
+       uint_t flags = TASKQ_PREPOPULATE;
+       boolean_t batch = B_FALSE;
 
-       spa->spa_state = POOL_STATE_ACTIVE;
-       spa->spa_mode = mode;
+       switch (mode) {
+       case zti_mode_null:
+               return (NULL);          /* no taskq needed */
+
+       case zti_mode_fixed:
+               ASSERT3U(value, >=, 1);
+               value = MAX(value, 1);
+               break;
+
+       case zti_mode_batch:
+               batch = B_TRUE;
+               flags |= TASKQ_THREADS_CPU_PCT;
+               value = zio_taskq_batch_pct;
+               break;
+
+       case zti_mode_online_percent:
+               flags |= TASKQ_THREADS_CPU_PCT;
+               break;
+
+       default:
+               panic("unrecognized mode for %s taskq (%u:%u) in "
+                   "spa_activate()",
+                   name, mode, value);
+               break;
+       }
 
-       spa->spa_normal_class = metaslab_class_create(zfs_metaslab_ops);
-       spa->spa_log_class = metaslab_class_create(zfs_metaslab_ops);
+       if (zio_taskq_sysdc && spa->spa_proc != &p0) {
+               if (batch)
+                       flags |= TASKQ_DC_BATCH;
 
+               return (taskq_create_sysdc(name, value, 50, INT_MAX,
+                   spa->spa_proc, zio_taskq_basedc, flags));
+       }
+       return (taskq_create_proc(name, value, maxclsyspri, 50, INT_MAX,
+           spa->spa_proc, flags));
+}
+
+static void
+spa_create_zio_taskqs(spa_t *spa)
+{
        for (int t = 0; t < ZIO_TYPES; t++) {
-               const zio_taskq_info_t *ztip = &zio_taskqs[t];
                for (int q = 0; q < ZIO_TASKQ_TYPES; q++) {
-                       enum zti_modes mode = ztip->zti_nthreads[q].zti_mode;
-                       uint_t value = ztip->zti_nthreads[q].zti_value;
+                       const zio_taskq_info_t *ztip = &zio_taskqs[t][q];
+                       enum zti_modes mode = ztip->zti_mode;
+                       uint_t value = ztip->zti_value;
                        char name[32];
 
                        (void) snprintf(name, sizeof (name),
-                           "%s_%s", ztip->zti_name, zio_taskq_types[q]);
+                           "%s_%s", zio_type_name[t], zio_taskq_types[q]);
 
-                       if (mode == zti_mode_tune) {
-                               mode = zio_taskq_tune_mode;
-                               value = zio_taskq_tune_value;
-                               if (mode == zti_mode_tune)
-                                       mode = zti_mode_online_percent;
-                       }
+                       spa->spa_zio_taskq[t][q] =
+                           spa_taskq_create(spa, name, mode, value);
+               }
+       }
+}
 
-                       switch (mode) {
-                       case zti_mode_fixed:
-                               ASSERT3U(value, >=, 1);
-                               value = MAX(value, 1);
+#ifdef _KERNEL
+static void
+spa_thread(void *arg)
+{
+       callb_cpr_t cprinfo;
 
-                               spa->spa_zio_taskq[t][q] = taskq_create(name,
-                                   value, maxclsyspri, 50, INT_MAX,
-                                   TASKQ_PREPOPULATE);
-                               break;
+       spa_t *spa = arg;
+       user_t *pu = PTOU(curproc);
 
-                       case zti_mode_online_percent:
-                               spa->spa_zio_taskq[t][q] = taskq_create(name,
-                                   value, maxclsyspri, 50, INT_MAX,
-                                   TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT);
-                               break;
+       CALLB_CPR_INIT(&cprinfo, &spa->spa_proc_lock, callb_generic_cpr,
+           spa->spa_name);
 
-                       case zti_mode_tune:
-                       default:
-                               panic("unrecognized mode for "
-                                   "zio_taskqs[%u]->zti_nthreads[%u] (%u:%u) "
-                                   "in spa_activate()",
-                                   t, q, mode, value);
-                               break;
+       ASSERT(curproc != &p0);
+       (void) snprintf(pu->u_psargs, sizeof (pu->u_psargs),
+           "zpool-%s", spa->spa_name);
+       (void) strlcpy(pu->u_comm, pu->u_psargs, sizeof (pu->u_comm));
+
+       /* bind this thread to the requested psrset */
+       if (zio_taskq_psrset_bind != PS_NONE) {
+               pool_lock();
+               mutex_enter(&cpu_lock);
+               mutex_enter(&pidlock);
+               mutex_enter(&curproc->p_lock);
+
+               if (cpupart_bind_thread(curthread, zio_taskq_psrset_bind,
+                   0, NULL, NULL) == 0)  {
+                       curthread->t_bind_pset = zio_taskq_psrset_bind;
+               } else {
+                       cmn_err(CE_WARN,
+                           "Couldn't bind process for zfs pool \"%s\" to "
+                           "pset %d\n", spa->spa_name, zio_taskq_psrset_bind);
+               }
+
+               mutex_exit(&curproc->p_lock);
+               mutex_exit(&pidlock);
+               mutex_exit(&cpu_lock);
+               pool_unlock();
+       }
+
+       if (zio_taskq_sysdc) {
+               sysdc_thread_enter(curthread, 100, 0);
+       }
+
+       spa->spa_proc = curproc;
+       spa->spa_did = curthread->t_did;
+
+       spa_create_zio_taskqs(spa);
+
+       mutex_enter(&spa->spa_proc_lock);
+       ASSERT(spa->spa_proc_state == SPA_PROC_CREATED);
+
+       spa->spa_proc_state = SPA_PROC_ACTIVE;
+       cv_broadcast(&spa->spa_proc_cv);
+
+       CALLB_CPR_SAFE_BEGIN(&cprinfo);
+       while (spa->spa_proc_state == SPA_PROC_ACTIVE)
+               cv_wait(&spa->spa_proc_cv, &spa->spa_proc_lock);
+       CALLB_CPR_SAFE_END(&cprinfo, &spa->spa_proc_lock);
+
+       ASSERT(spa->spa_proc_state == SPA_PROC_DEACTIVATE);
+       spa->spa_proc_state = SPA_PROC_GONE;
+       spa->spa_proc = &p0;
+       cv_broadcast(&spa->spa_proc_cv);
+       CALLB_CPR_EXIT(&cprinfo);       /* drops spa_proc_lock */
+
+       mutex_enter(&curproc->p_lock);
+       lwp_exit();
+}
+#endif
+
+/*
+ * Activate an uninitialized pool.
+ */
+static void
+spa_activate(spa_t *spa, int mode)
+{
+       ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);
+
+       spa->spa_state = POOL_STATE_ACTIVE;
+       spa->spa_mode = mode;
+
+       spa->spa_normal_class = metaslab_class_create(spa, zfs_metaslab_ops);
+       spa->spa_log_class = metaslab_class_create(spa, zfs_metaslab_ops);
+
+       /* Try to create a covering process */
+       mutex_enter(&spa->spa_proc_lock);
+       ASSERT(spa->spa_proc_state == SPA_PROC_NONE);
+       ASSERT(spa->spa_proc == &p0);
+       spa->spa_did = 0;
+
+       /* Only create a process if we're going to be around a while. */
+       if (spa_create_process && strcmp(spa->spa_name, TRYIMPORT_NAME) != 0) {
+               if (newproc(spa_thread, (caddr_t)spa, syscid, maxclsyspri,
+                   NULL, 0) == 0) {
+                       spa->spa_proc_state = SPA_PROC_CREATED;
+                       while (spa->spa_proc_state == SPA_PROC_CREATED) {
+                               cv_wait(&spa->spa_proc_cv,
+                                   &spa->spa_proc_lock);
                        }
+                       ASSERT(spa->spa_proc_state == SPA_PROC_ACTIVE);
+                       ASSERT(spa->spa_proc != &p0);
+                       ASSERT(spa->spa_did != 0);
+               } else {
+#ifdef _KERNEL
+                       cmn_err(CE_WARN,
+                           "Couldn't create process for zfs pool \"%s\"\n",
+                           spa->spa_name);
+#endif
                }
        }
+       mutex_exit(&spa->spa_proc_lock);
+
+       /* If we didn't create a process, we need to create our taskqs. */
+       if (spa->spa_proc == &p0) {
+               spa_create_zio_taskqs(spa);
+       }
 
        list_create(&spa->spa_config_dirty_list, sizeof (vdev_t),
            offsetof(vdev_t, vdev_config_dirty_node));
@@ -658,7 +816,8 @@ spa_deactivate(spa_t *spa)
 
        for (int t = 0; t < ZIO_TYPES; t++) {
                for (int q = 0; q < ZIO_TASKQ_TYPES; q++) {
-                       taskq_destroy(spa->spa_zio_taskq[t][q]);
+                       if (spa->spa_zio_taskq[t][q] != NULL)
+                               taskq_destroy(spa->spa_zio_taskq[t][q]);
                        spa->spa_zio_taskq[t][q] = NULL;
                }
        }
@@ -679,6 +838,31 @@ spa_deactivate(spa_t *spa)
        avl_destroy(&spa->spa_errlist_last);
 
        spa->spa_state = POOL_STATE_UNINITIALIZED;
+
+       mutex_enter(&spa->spa_proc_lock);
+       if (spa->spa_proc_state != SPA_PROC_NONE) {
+               ASSERT(spa->spa_proc_state == SPA_PROC_ACTIVE);
+               spa->spa_proc_state = SPA_PROC_DEACTIVATE;
+               cv_broadcast(&spa->spa_proc_cv);
+               while (spa->spa_proc_state == SPA_PROC_DEACTIVATE) {
+                       ASSERT(spa->spa_proc != &p0);
+                       cv_wait(&spa->spa_proc_cv, &spa->spa_proc_lock);
+               }
+               ASSERT(spa->spa_proc_state == SPA_PROC_GONE);
+               spa->spa_proc_state = SPA_PROC_NONE;
+       }
+       ASSERT(spa->spa_proc == &p0);
+       mutex_exit(&spa->spa_proc_lock);
+
+       /*
+        * We want to make sure spa_thread() has actually exited the ZFS
+        * module, so that the module can't be unloaded out from underneath
+        * it.
+        */
+       if (spa->spa_did != 0) {
+               thread_join(spa->spa_did);
+               spa->spa_did = 0;
+       }
 }
 
 /*
@@ -759,14 +943,19 @@ spa_unload(spa_t *spa)
                spa->spa_async_zio_root = NULL;
        }
 
+       bpobj_close(&spa->spa_deferred_bpobj);
+
        /*
         * Close the dsl pool.
         */
        if (spa->spa_dsl_pool) {
                dsl_pool_close(spa->spa_dsl_pool);
                spa->spa_dsl_pool = NULL;
+               spa->spa_meta_objset = NULL;
        }
 
+       ddt_unload(spa);
+
        spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
 
        /*
@@ -919,7 +1108,7 @@ spa_load_spares(spa_t *spa)
            KM_SLEEP);
        for (i = 0; i < spa->spa_spares.sav_count; i++)
                spares[i] = vdev_config_generate(spa,
-                   spa->spa_spares.sav_vdevs[i], B_TRUE, B_TRUE, B_FALSE);
+                   spa->spa_spares.sav_vdevs[i], B_TRUE, VDEV_CONFIG_SPARE);
        VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
            ZPOOL_CONFIG_SPARES, spares, spa->spa_spares.sav_count) == 0);
        for (i = 0; i < spa->spa_spares.sav_count; i++)
@@ -1045,7 +1234,7 @@ spa_load_l2cache(spa_t *spa)
        l2cache = kmem_alloc(sav->sav_count * sizeof (void *), KM_SLEEP);
        for (i = 0; i < sav->sav_count; i++)
                l2cache[i] = vdev_config_generate(spa,
-                   sav->sav_vdevs[i], B_TRUE, B_FALSE, B_TRUE);
+                   sav->sav_vdevs[i], B_TRUE, VDEV_CONFIG_L2CACHE);
        VERIFY(nvlist_add_nvlist_array(sav->sav_config,
            ZPOOL_CONFIG_L2CACHE, l2cache, sav->sav_count) == 0);
 out:
@@ -1099,26 +1288,23 @@ spa_check_removed(vdev_t *vd)
  * that the label does not contain the most up-to-date information.
  */
 void
-spa_load_log_state(spa_t *spa)
+spa_load_log_state(spa_t *spa, nvlist_t *nv)
 {
-       nvlist_t *nv, *nvroot, **child;
-       uint64_t is_log;
-       uint_t children;
-       vdev_t *rvd = spa->spa_root_vdev;
-
-       VERIFY(load_nvlist(spa, spa->spa_config_object, &nv) == 0);
-       VERIFY(nvlist_lookup_nvlist(nv, ZPOOL_CONFIG_VDEV_TREE, &nvroot) == 0);
-       VERIFY(nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_CHILDREN,
-           &child, &children) == 0);
+       vdev_t *ovd, *rvd = spa->spa_root_vdev;
 
-       for (int c = 0; c < children; c++) {
-               vdev_t *tvd = rvd->vdev_child[c];
+       /*
+        * Load the original root vdev tree from the passed config.
+        */
+       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+       VERIFY(spa_config_parse(spa, &ovd, nv, NULL, 0, VDEV_ALLOC_LOAD) == 0);
 
-               if (nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_LOG,
-                   &is_log) == 0 && is_log)
-                       vdev_load_log_state(tvd, child[c]);
+       for (int c = 0; c < rvd->vdev_children; c++) {
+               vdev_t *cvd = rvd->vdev_child[c];
+               if (cvd->vdev_islog)
+                       vdev_load_log_state(cvd, ovd->vdev_child[c]);
        }
-       nvlist_free(nv);
+       vdev_free(ovd);
+       spa_config_exit(spa, SCL_ALL, FTAG);
 }
 
 /*
@@ -1133,7 +1319,7 @@ spa_check_logs(spa_t *spa)
        case SPA_LOG_UNKNOWN:
                if (dmu_objset_find(spa->spa_name, zil_check_log_chain, NULL,
                    DS_FIND_CHILDREN)) {
-                       spa->spa_log_state = SPA_LOG_MISSING;
+                       spa_set_log_state(spa, SPA_LOG_MISSING);
                        return (1);
                }
                break;
@@ -1141,186 +1327,486 @@ spa_check_logs(spa_t *spa)
        return (0);
 }
 
-/*
- * Load an existing storage pool, using the pool's builtin spa_config as a
- * source of configuration information.
- */
-static int
-spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
+static boolean_t
+spa_passivate_log(spa_t *spa)
 {
-       int error = 0;
-       nvlist_t *nvroot = NULL;
-       vdev_t *rvd;
-       uberblock_t *ub = &spa->spa_uberblock;
-       uint64_t config_cache_txg = spa->spa_config_txg;
-       uint64_t pool_guid;
-       uint64_t version;
-       uint64_t autoreplace = 0;
-       int orig_mode = spa->spa_mode;
-       char *ereport = FM_EREPORT_ZFS_POOL;
+       vdev_t *rvd = spa->spa_root_vdev;
+       boolean_t slog_found = B_FALSE;
 
-       /*
-        * If this is an untrusted config, access the pool in read-only mode.
-        * This prevents things like resilvering recently removed devices.
-        */
-       if (!mosconfig)
-               spa->spa_mode = FREAD;
+       ASSERT(spa_config_held(spa, SCL_ALLOC, RW_WRITER));
 
-       ASSERT(MUTEX_HELD(&spa_namespace_lock));
+       if (!spa_has_slogs(spa))
+               return (B_FALSE);
 
-       spa->spa_load_state = state;
+       for (int c = 0; c < rvd->vdev_children; c++) {
+               vdev_t *tvd = rvd->vdev_child[c];
+               metaslab_group_t *mg = tvd->vdev_mg;
 
-       if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvroot) ||
-           nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid)) {
-               error = EINVAL;
-               goto out;
+               if (tvd->vdev_islog) {
+                       metaslab_group_passivate(mg);
+                       slog_found = B_TRUE;
+               }
        }
 
-       /*
-        * Versioning wasn't explicitly added to the label until later, so if
-        * it's not present treat it as the initial version.
-        */
-       if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_VERSION, &version) != 0)
-               version = SPA_VERSION_INITIAL;
-
-       (void) nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_TXG,
-           &spa->spa_config_txg);
+       return (slog_found);
+}
 
-       if ((state == SPA_LOAD_IMPORT || state == SPA_LOAD_TRYIMPORT) &&
-           spa_guid_exists(pool_guid, 0)) {
-               error = EEXIST;
-               goto out;
-       }
+static void
+spa_activate_log(spa_t *spa)
+{
+       vdev_t *rvd = spa->spa_root_vdev;
 
-       spa->spa_load_guid = pool_guid;
+       ASSERT(spa_config_held(spa, SCL_ALLOC, RW_WRITER));
 
-       /*
-        * Create "The Godfather" zio to hold all async IOs
-        */
-       spa->spa_async_zio_root = zio_root(spa, NULL, NULL,
-           ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_GODFATHER);
+       for (int c = 0; c < rvd->vdev_children; c++) {
+               vdev_t *tvd = rvd->vdev_child[c];
+               metaslab_group_t *mg = tvd->vdev_mg;
 
-       /*
-        * Parse the configuration into a vdev tree.  We explicitly set the
-        * value that will be returned by spa_version() since parsing the
-        * configuration requires knowing the version number.
-        */
-       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-       spa->spa_ubsync.ub_version = version;
-       error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, VDEV_ALLOC_LOAD);
-       spa_config_exit(spa, SCL_ALL, FTAG);
+               if (tvd->vdev_islog)
+                       metaslab_group_activate(mg);
+       }
+}
 
-       if (error != 0)
-               goto out;
+int
+spa_offline_log(spa_t *spa)
+{
+       int error = 0;
 
-       ASSERT(spa->spa_root_vdev == rvd);
-       ASSERT(spa_guid(spa) == pool_guid);
+       if ((error = dmu_objset_find(spa_name(spa), zil_vdev_offline,
+           NULL, DS_FIND_CHILDREN)) == 0) {
 
-       /*
-        * Try to open all vdevs, loading each label in the process.
-        */
-       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-       error = vdev_open(rvd);
-       spa_config_exit(spa, SCL_ALL, FTAG);
-       if (error != 0)
-               goto out;
+               /*
+                * We successfully offlined the log device, sync out the
+                * current txg so that the "stubby" block can be removed
+                * by zil_sync().
+                */
+               txg_wait_synced(spa->spa_dsl_pool, 0);
+       }
+       return (error);
+}
 
-       /*
-        * 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.
-        */
-       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-       error = vdev_validate(rvd);
-       spa_config_exit(spa, SCL_ALL, FTAG);
-       if (error != 0)
-               goto out;
+static void
+spa_aux_check_removed(spa_aux_vdev_t *sav)
+{
+       for (int i = 0; i < sav->sav_count; i++)
+               spa_check_removed(sav->sav_vdevs[i]);
+}
 
-       if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
-               error = ENXIO;
-               goto out;
-       }
+void
+spa_claim_notify(zio_t *zio)
+{
+       spa_t *spa = zio->io_spa;
 
-       /*
-        * Find the best uberblock.
-        */
-       vdev_uberblock_load(NULL, rvd, ub);
+       if (zio->io_error)
+               return;
 
-       /*
-        * If we weren't able to find a single valid uberblock, return failure.
-        */
-       if (ub->ub_txg == 0) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = ENXIO;
-               goto out;
-       }
+       mutex_enter(&spa->spa_props_lock);      /* any mutex will do */
+       if (spa->spa_claim_max_txg < zio->io_bp->blk_birth)
+               spa->spa_claim_max_txg = zio->io_bp->blk_birth;
+       mutex_exit(&spa->spa_props_lock);
+}
 
-       /*
-        * If the pool is newer than the code, we can't open it.
-        */
-       if (ub->ub_version > SPA_VERSION) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_VERSION_NEWER);
-               error = ENOTSUP;
-               goto out;
-       }
+typedef struct spa_load_error {
+       uint64_t        sle_meta_count;
+       uint64_t        sle_data_count;
+} spa_load_error_t;
 
-       /*
-        * If the vdev guid sum doesn't match the uberblock, we have an
-        * incomplete configuration.
-        */
-       if (rvd->vdev_guid_sum != ub->ub_guid_sum && mosconfig) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_BAD_GUID_SUM);
-               error = ENXIO;
-               goto out;
-       }
+static void
+spa_load_verify_done(zio_t *zio)
+{
+       blkptr_t *bp = zio->io_bp;
+       spa_load_error_t *sle = zio->io_private;
+       dmu_object_type_t type = BP_GET_TYPE(bp);
+       int error = zio->io_error;
 
-       /*
-        * Initialize internal SPA structures.
-        */
-       spa->spa_state = POOL_STATE_ACTIVE;
-       spa->spa_ubsync = spa->spa_uberblock;
-       spa->spa_first_txg = spa_last_synced_txg(spa) + 1;
-       error = dsl_pool_open(spa, spa->spa_first_txg, &spa->spa_dsl_pool);
        if (error) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               goto out;
+               if ((BP_GET_LEVEL(bp) != 0 || dmu_ot[type].ot_metadata) &&
+                   type != DMU_OT_INTENT_LOG)
+                       atomic_add_64(&sle->sle_meta_count, 1);
+               else
+                       atomic_add_64(&sle->sle_data_count, 1);
        }
-       spa->spa_meta_objset = spa->spa_dsl_pool->dp_meta_objset;
+       zio_data_buf_free(zio->io_data, zio->io_size);
+}
 
-       if (zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CONFIG,
-           sizeof (uint64_t), 1, &spa->spa_config_object) != 0) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
+/*ARGSUSED*/
+static int
+spa_load_verify_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
+    arc_buf_t *pbuf, const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
+{
+       if (bp != NULL) {
+               zio_t *rio = arg;
+               size_t size = BP_GET_PSIZE(bp);
+               void *data = zio_data_buf_alloc(size);
+
+               zio_nowait(zio_read(rio, spa, bp, data, size,
+                   spa_load_verify_done, rio->io_private, ZIO_PRIORITY_SCRUB,
+                   ZIO_FLAG_SPECULATIVE | ZIO_FLAG_CANFAIL |
+                   ZIO_FLAG_SCRUB | ZIO_FLAG_RAW, zb));
        }
+       return (0);
+}
 
-       if (!mosconfig) {
-               nvlist_t *newconfig;
-               uint64_t hostid;
+static int
+spa_load_verify(spa_t *spa)
+{
+       zio_t *rio;
+       spa_load_error_t sle = { 0 };
+       zpool_rewind_policy_t policy;
+       boolean_t verify_ok = B_FALSE;
+       int error;
 
-               if (load_nvlist(spa, spa->spa_config_object, &newconfig) != 0) {
-                       vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_CORRUPT_DATA);
-                       error = EIO;
-                       goto out;
-               }
+       zpool_get_rewind_policy(spa->spa_config, &policy);
 
-               if (!spa_is_root(spa) && nvlist_lookup_uint64(newconfig,
+       if (policy.zrp_request & ZPOOL_NEVER_REWIND)
+               return (0);
+
+       rio = zio_root(spa, NULL, &sle,
+           ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE);
+
+       error = traverse_pool(spa, spa->spa_verify_min_txg,
+           TRAVERSE_PRE | TRAVERSE_PREFETCH, spa_load_verify_cb, rio);
+
+       (void) zio_wait(rio);
+
+       spa->spa_load_meta_errors = sle.sle_meta_count;
+       spa->spa_load_data_errors = sle.sle_data_count;
+
+       if (!error && sle.sle_meta_count <= policy.zrp_maxmeta &&
+           sle.sle_data_count <= policy.zrp_maxdata) {
+               verify_ok = B_TRUE;
+               spa->spa_load_txg = spa->spa_uberblock.ub_txg;
+               spa->spa_load_txg_ts = spa->spa_uberblock.ub_timestamp;
+       } else {
+               spa->spa_load_max_txg = spa->spa_uberblock.ub_txg;
+       }
+
+       if (error) {
+               if (error != ENXIO && error != EIO)
+                       error = EIO;
+               return (error);
+       }
+
+       return (verify_ok ? 0 : EIO);
+}
+
+/*
+ * Find a value in the pool props object.
+ */
+static void
+spa_prop_find(spa_t *spa, zpool_prop_t prop, uint64_t *val)
+{
+       (void) zap_lookup(spa->spa_meta_objset, spa->spa_pool_props_object,
+           zpool_prop_to_name(prop), sizeof (uint64_t), 1, val);
+}
+
+/*
+ * Find a value in the pool directory object.
+ */
+static int
+spa_dir_prop(spa_t *spa, const char *name, uint64_t *val)
+{
+       return (zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
+           name, sizeof (uint64_t), 1, val));
+}
+
+static int
+spa_vdev_err(vdev_t *vdev, vdev_aux_t aux, int err)
+{
+       vdev_set_state(vdev, B_TRUE, VDEV_STATE_CANT_OPEN, aux);
+       return (err);
+}
+
+/*
+ * 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
+ * pool have that entry in their config, but only the splitting one contains
+ * a list of all the guids of the vdevs that are being split off.
+ *
+ * This function determines what to do with that list: either rejoin
+ * all the disks to the pool, or complete the splitting process.  To attempt
+ * the rejoin, each disk that is offlined is marked online again, and
+ * we do a reopen() call.  If the vdev label for every disk that was
+ * marked online indicates it was successfully split off (VDEV_AUX_SPLIT_POOL)
+ * then we call vdev_split() on each disk, and complete the split.
+ *
+ * Otherwise we leave the config alone, with all the vdevs in place in
+ * the original pool.
+ */
+static void
+spa_try_repair(spa_t *spa, nvlist_t *config)
+{
+       uint_t extracted;
+       uint64_t *glist;
+       uint_t i, gcount;
+       nvlist_t *nvl;
+       vdev_t **vd;
+       boolean_t attempt_reopen;
+
+       if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT, &nvl) != 0)
+               return;
+
+       /* check that the config is complete */
+       if (nvlist_lookup_uint64_array(nvl, ZPOOL_CONFIG_SPLIT_LIST,
+           &glist, &gcount) != 0)
+               return;
+
+       vd = kmem_zalloc(gcount * sizeof (vdev_t *), KM_SLEEP);
+
+       /* attempt to online all the vdevs & validate */
+       attempt_reopen = B_TRUE;
+       for (i = 0; i < gcount; i++) {
+               if (glist[i] == 0)      /* vdev is hole */
+                       continue;
+
+               vd[i] = spa_lookup_by_guid(spa, glist[i], B_FALSE);
+               if (vd[i] == NULL) {
+                       /*
+                        * Don't bother attempting to reopen the disks;
+                        * just do the split.
+                        */
+                       attempt_reopen = B_FALSE;
+               } else {
+                       /* attempt to re-online it */
+                       vd[i]->vdev_offline = B_FALSE;
+               }
+       }
+
+       if (attempt_reopen) {
+               vdev_reopen(spa->spa_root_vdev);
+
+               /* check each device to see what state it's in */
+               for (extracted = 0, i = 0; i < gcount; i++) {
+                       if (vd[i] != NULL &&
+                           vd[i]->vdev_stat.vs_aux != VDEV_AUX_SPLIT_POOL)
+                               break;
+                       ++extracted;
+               }
+       }
+
+       /*
+        * If every disk has been moved to the new pool, or if we never
+        * even attempted to look at them, then we split them off for
+        * good.
+        */
+       if (!attempt_reopen || gcount == extracted) {
+               for (i = 0; i < gcount; i++)
+                       if (vd[i] != NULL)
+                               vdev_split(vd[i]);
+               vdev_reopen(spa->spa_root_vdev);
+       }
+
+       kmem_free(vd, gcount * sizeof (vdev_t *));
+}
+
+static int
+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;
+       int error;
+       uint64_t pool_guid;
+       nvlist_t *nvl;
+
+       if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid))
+               return (EINVAL);
+
+       /*
+        * 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 = EEXIST;
+       } else {
+               spa->spa_load_guid = pool_guid;
+
+               if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT,
+                   &nvl) == 0) {
+                       VERIFY(nvlist_dup(nvl, &spa->spa_config_splitting,
+                           KM_SLEEP) == 0);
+               }
+
+               error = spa_load_impl(spa, pool_guid, config, state, type,
+                   mosconfig, &ereport);
+       }
+
+       spa->spa_minref = refcount_count(&spa->spa_refcount);
+       if (error && error != EBADF)
+               zfs_ereport_post(ereport, spa, NULL, NULL, 0, 0);
+       spa->spa_load_state = error ? SPA_LOAD_ERROR : SPA_LOAD_NONE;
+       spa->spa_ena = 0;
+
+       return (error);
+}
+
+/*
+ * Load an existing storage pool, using the pool's builtin spa_config as a
+ * source of configuration information.
+ */
+static int
+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)
+{
+       int error = 0;
+       nvlist_t *nvroot = NULL;
+       vdev_t *rvd;
+       uberblock_t *ub = &spa->spa_uberblock;
+       uint64_t config_cache_txg = spa->spa_config_txg;
+       int orig_mode = spa->spa_mode;
+       int parse;
+       uint64_t obj;
+
+       /*
+        * If this is an untrusted config, access the pool in read-only mode.
+        * This prevents things like resilvering recently removed devices.
+        */
+       if (!mosconfig)
+               spa->spa_mode = FREAD;
+
+       ASSERT(MUTEX_HELD(&spa_namespace_lock));
+
+       spa->spa_load_state = state;
+
+       if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvroot))
+               return (EINVAL);
+
+       parse = (type == SPA_IMPORT_EXISTING ?
+           VDEV_ALLOC_LOAD : VDEV_ALLOC_SPLIT);
+
+       /*
+        * Create "The Godfather" zio to hold all async IOs
+        */
+       spa->spa_async_zio_root = zio_root(spa, NULL, NULL,
+           ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE | ZIO_FLAG_GODFATHER);
+
+       /*
+        * Parse the configuration into a vdev tree.  We explicitly set the
+        * value that will be returned by spa_version() since parsing the
+        * configuration requires knowing the version number.
+        */
+       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+       error = spa_config_parse(spa, &rvd, nvroot, NULL, 0, parse);
+       spa_config_exit(spa, SCL_ALL, FTAG);
+
+       if (error != 0)
+               return (error);
+
+       ASSERT(spa->spa_root_vdev == rvd);
+
+       if (type != SPA_IMPORT_ASSEMBLE) {
+               ASSERT(spa_guid(spa) == pool_guid);
+       }
+
+       /*
+        * Try to open all vdevs, loading each label in the process.
+        */
+       spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
+       error = vdev_open(rvd);
+       spa_config_exit(spa, SCL_ALL, FTAG);
+       if (error != 0)
+               return (error);
+
+       /*
+        * 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);
+               spa_config_exit(spa, SCL_ALL, FTAG);
+
+               if (error != 0)
+                       return (error);
+
+               if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN)
+                       return (ENXIO);
+       }
+
+       /*
+        * Find the best uberblock.
+        */
+       vdev_uberblock_load(NULL, rvd, ub);
+
+       /*
+        * If we weren't able to find a single valid uberblock, return failure.
+        */
+       if (ub->ub_txg == 0)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, ENXIO));
+
+       /*
+        * If the pool is newer than the code, we can't open it.
+        */
+       if (ub->ub_version > SPA_VERSION)
+               return (spa_vdev_err(rvd, VDEV_AUX_VERSION_NEWER, ENOTSUP));
+
+       /*
+        * If the vdev guid sum doesn't match the uberblock, we have an
+        * incomplete configuration.
+        */
+       if (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, config);
+               spa_config_exit(spa, SCL_ALL, FTAG);
+               nvlist_free(spa->spa_config_splitting);
+               spa->spa_config_splitting = NULL;
+       }
+
+       /*
+        * Initialize internal SPA structures.
+        */
+       spa->spa_state = POOL_STATE_ACTIVE;
+       spa->spa_ubsync = spa->spa_uberblock;
+       spa->spa_verify_min_txg = spa->spa_extreme_rewind ?
+           TXG_INITIAL - 1 : spa_last_synced_txg(spa) - TXG_DEFER_SIZE - 1;
+       spa->spa_first_txg = spa->spa_last_ubsync_txg ?
+           spa->spa_last_ubsync_txg : spa_last_synced_txg(spa) + 1;
+       spa->spa_claim_max_txg = spa->spa_first_txg;
+       spa->spa_prev_software_version = ub->ub_software_version;
+
+       error = dsl_pool_open(spa, spa->spa_first_txg, &spa->spa_dsl_pool);
+       if (error)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+       spa->spa_meta_objset = spa->spa_dsl_pool->dp_meta_objset;
+
+       if (spa_dir_prop(spa, DMU_POOL_CONFIG, &spa->spa_config_object) != 0)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+
+       if (!mosconfig) {
+               uint64_t hostid;
+               nvlist_t *policy = NULL, *nvconfig;
+
+               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(newconfig,
+                       VERIFY(nvlist_lookup_string(nvconfig,
                            ZPOOL_CONFIG_HOSTNAME, &hostname) == 0);
 
 #ifdef _KERNEL
@@ -1334,185 +1820,133 @@ spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
 #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://www.sun.com/msg/ZFS-8000-EY",
                                    spa_name(spa), hostname,
                                    (unsigned long)hostid);
-                               error = EBADF;
-                               goto out;
+                               return (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, newconfig);
+               spa_config_set(spa, nvconfig);
                spa_unload(spa);
                spa_deactivate(spa);
                spa_activate(spa, orig_mode);
 
-               return (spa_load(spa, newconfig, state, B_TRUE));
+               return (spa_load(spa, state, SPA_IMPORT_EXISTING, B_TRUE));
        }
 
-       if (zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPLIST,
-           sizeof (uint64_t), 1, &spa->spa_sync_bplist_obj) != 0) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       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)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
        /*
         * Load the bit that tells us to use the new accounting function
         * (raid-z deflation).  If we have an older pool, this will not
         * be present.
         */
-       error = zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_DEFLATE,
-           sizeof (uint64_t), 1, &spa->spa_deflate);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       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);
+       if (error != 0 && error != ENOENT)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
        /*
         * Load the persistent error log.  If we have an older pool, this will
         * not be present.
         */
-       error = zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_ERRLOG_LAST,
-           sizeof (uint64_t), 1, &spa->spa_errlog_last);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       error = 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 = zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_ERRLOG_SCRUB,
-           sizeof (uint64_t), 1, &spa->spa_errlog_scrub);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       error = spa_dir_prop(spa, DMU_POOL_ERRLOG_SCRUB,
+           &spa->spa_errlog_scrub);
+       if (error != 0 && error != ENOENT)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
        /*
         * Load the history object.  If we have an older pool, this
         * will not be present.
         */
-       error = zap_lookup(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_HISTORY,
-           sizeof (uint64_t), 1, &spa->spa_history);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       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));
+
+       /*
+        * 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.
+        */
 
        /*
         * Load any hot spares for this pool.
         */
-       error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
-           DMU_POOL_SPARES, sizeof (uint64_t), 1, &spa->spa_spares.sav_object);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
-       if (error == 0) {
+       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) {
-                       vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_CORRUPT_DATA);
-                       error = EIO;
-                       goto out;
-               }
+                   &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);
                spa_config_exit(spa, SCL_ALL, FTAG);
+       } else if (error == 0) {
+               spa->spa_spares.sav_sync = B_TRUE;
        }
 
        /*
         * Load any level 2 ARC devices for this pool.
         */
-       error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
-           DMU_POOL_L2CACHE, sizeof (uint64_t), 1,
+       error = spa_dir_prop(spa, DMU_POOL_L2CACHE,
            &spa->spa_l2cache.sav_object);
-       if (error != 0 && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
-       if (error == 0) {
+       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) {
-                       vdev_set_state(rvd, B_TRUE,
-                           VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_CORRUPT_DATA);
-                       error = EIO;
-                       goto out;
-               }
+                   &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);
                spa_config_exit(spa, SCL_ALL, FTAG);
+       } else if (error == 0) {
+               spa->spa_l2cache.sav_sync = B_TRUE;
        }
 
-       spa_load_log_state(spa);
-
-       if (spa_check_logs(spa)) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_BAD_LOG);
-               error = ENXIO;
-               ereport = FM_EREPORT_ZFS_LOG_REPLAY;
-               goto out;
-       }
-
-
        spa->spa_delegation = zpool_prop_default_numeric(ZPOOL_PROP_DELEGATION);
 
-       error = zap_lookup(spa->spa_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
-           DMU_POOL_PROPS, sizeof (uint64_t), 1, &spa->spa_pool_props_object);
-
-       if (error && error != ENOENT) {
-               vdev_set_state(rvd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
-               error = EIO;
-               goto out;
-       }
+       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) {
-               (void) zap_lookup(spa->spa_meta_objset,
-                   spa->spa_pool_props_object,
-                   zpool_prop_to_name(ZPOOL_PROP_BOOTFS),
-                   sizeof (uint64_t), 1, &spa->spa_bootfs);
-               (void) zap_lookup(spa->spa_meta_objset,
-                   spa->spa_pool_props_object,
-                   zpool_prop_to_name(ZPOOL_PROP_AUTOREPLACE),
-                   sizeof (uint64_t), 1, &autoreplace);
-               (void) zap_lookup(spa->spa_meta_objset,
-                   spa->spa_pool_props_object,
-                   zpool_prop_to_name(ZPOOL_PROP_DELEGATION),
-                   sizeof (uint64_t), 1, &spa->spa_delegation);
-               (void) zap_lookup(spa->spa_meta_objset,
-                   spa->spa_pool_props_object,
-                   zpool_prop_to_name(ZPOOL_PROP_FAILUREMODE),
-                   sizeof (uint64_t), 1, &spa->spa_failmode);
-               (void) zap_lookup(spa->spa_meta_objset,
-                   spa->spa_pool_props_object,
-                   zpool_prop_to_name(ZPOOL_PROP_AUTOEXPAND),
-                   sizeof (uint64_t), 1, &spa->spa_autoexpand);
+               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);
        }
 
        /*
@@ -1522,8 +1956,18 @@ spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
         * unopenable vdevs so that the normal autoreplace handler can take
         * over.
         */
-       if (autoreplace && 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
+                * at this point we're using the spare definitions from
+                * the MOS config, not necessarily from the userland config.
+                */
+               if (state != SPA_LOAD_IMPORT) {
+                       spa_aux_check_removed(&spa->spa_spares);
+                       spa_aux_check_removed(&spa->spa_l2cache);
+               }
+       }
 
        /*
         * Load the vdev state for all toplevel vdevs.
@@ -1541,12 +1985,48 @@ spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
         * Check the state of the root vdev.  If it can't be opened, it
         * indicates one or more toplevel vdevs are faulted.
         */
-       if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN) {
-               error = ENXIO;
-               goto out;
+       if (rvd->vdev_state <= VDEV_STATE_CANT_OPEN)
+               return (ENXIO);
+
+       /*
+        * Load the DDTs (dedup tables).
+        */
+       error = ddt_load(spa);
+       if (error != 0)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+
+       spa_update_dspace(spa);
+
+       if (state != SPA_LOAD_TRYIMPORT) {
+               error = spa_load_verify(spa);
+               if (error)
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
+                           error));
        }
 
-       if (spa_writeable(spa)) {
+       /*
+        * Load the intent log state and check log integrity.  If we're
+        * assembling a pool from a split, the log is not transferred over.
+        */
+       if (type != SPA_IMPORT_ASSEMBLE) {
+               nvlist_t *nvconfig;
+
+               if (load_nvlist(spa, spa->spa_config_object, &nvconfig) != 0)
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+
+               VERIFY(nvlist_lookup_nvlist(nvconfig, ZPOOL_CONFIG_VDEV_TREE,
+                   &nvroot) == 0);
+               spa_load_log_state(spa, nvroot);
+               nvlist_free(nvconfig);
+
+               if (spa_check_logs(spa)) {
+                       *ereport = FM_EREPORT_ZFS_LOG_REPLAY;
+                       return (spa_vdev_err(rvd, VDEV_AUX_BAD_LOG, ENXIO));
+               }
+       }
+
+       if (spa_writeable(spa) && (state == SPA_LOAD_RECOVER ||
+           spa->spa_load_max_txg == UINT64_MAX)) {
                dmu_tx_t *tx;
                int need_update = B_FALSE;
 
@@ -1555,60 +2035,154 @@ spa_load(spa_t *spa, nvlist_t *config, spa_load_state_t state, int mosconfig)
                /*
                 * 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(spa_get_dsl(spa),
                    spa_first_txg(spa));
                (void) dmu_objset_find(spa_name(spa),
                    zil_claim, tx, DS_FIND_CHILDREN);
                dmu_tx_commit(tx);
 
-               spa->spa_log_state = SPA_LOG_GOOD;
-               spa->spa_sync_on = B_TRUE;
-               txg_sync_start(spa->spa_dsl_pool);
+               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);
+
+               /*
+                * 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 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);
+
+               /*
+                * If the config cache is stale, or we have uninitialized
+                * metaslabs (see spa_vdev_add()), then update the config.
+                *
+                * If spa_load_verbatim is true, trust the current
+                * in-core spa_config and update the disk labels.
+                */
+               if (config_cache_txg != spa->spa_config_txg ||
+                   state == SPA_LOAD_IMPORT || spa->spa_load_verbatim ||
+                   state == SPA_LOAD_RECOVER)
+                       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(rvd, NULL, NULL))
+                       spa_async_request(spa, SPA_ASYNC_RESILVER);
+
+               /*
+                * Delete any inconsistent datasets.
+                */
+               (void) dmu_objset_find(spa_name(spa),
+                   dsl_destroy_inconsistent, NULL, DS_FIND_CHILDREN);
+
+               /*
+                * Clean up any stale temporary dataset userrefs.
+                */
+               dsl_pool_clean_tmp_userrefs(spa->spa_dsl_pool);
+       }
+
+       return (0);
+}
+
+static int
+spa_load_retry(spa_t *spa, spa_load_state_t state, int mosconfig)
+{
+       spa_unload(spa);
+       spa_deactivate(spa);
+
+       spa->spa_load_max_txg--;
+
+       spa_activate(spa, spa_mode_global);
+       spa_async_suspend(spa);
+
+       return (spa_load(spa, state, SPA_IMPORT_EXISTING, mosconfig));
+}
+
+static int
+spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
+    uint64_t max_request, int rewind_flags)
+{
+       nvlist_t *config = NULL;
+       int load_error, rewind_error;
+       uint64_t safe_rewind_txg;
+       uint64_t min_txg;
 
-               /*
-                * Wait for all claims to sync.
-                */
-               txg_wait_synced(spa->spa_dsl_pool, 0);
+       if (spa->spa_load_txg && state == SPA_LOAD_RECOVER) {
+               spa->spa_load_max_txg = spa->spa_load_txg;
+               spa_set_log_state(spa, SPA_LOG_CLEAR);
+       } else {
+               spa->spa_load_max_txg = max_request;
+       }
 
-               /*
-                * If the config cache is stale, or we have uninitialized
-                * metaslabs (see spa_vdev_add()), then update the config.
-                *
-                * If spa_load_verbatim is true, trust the current
-                * in-core spa_config and update the disk labels.
-                */
-               if (config_cache_txg != spa->spa_config_txg ||
-                   state == SPA_LOAD_IMPORT || spa->spa_load_verbatim)
-                       need_update = B_TRUE;
+       load_error = rewind_error = spa_load(spa, state, SPA_IMPORT_EXISTING,
+           mosconfig);
+       if (load_error == 0)
+               return (0);
 
-               for (int c = 0; c < rvd->vdev_children; c++)
-                       if (rvd->vdev_child[c]->vdev_ms_array == 0)
-                               need_update = B_TRUE;
+       if (spa->spa_root_vdev != NULL)
+               config = spa_config_generate(spa, NULL, -1ULL, 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);
+       spa->spa_last_ubsync_txg = spa->spa_uberblock.ub_txg;
+       spa->spa_last_ubsync_txg_ts = spa->spa_uberblock.ub_timestamp;
 
-               /*
-                * Check all DTLs to see if anything needs resilvering.
-                */
-               if (vdev_resilver_needed(rvd, NULL, NULL))
-                       spa_async_request(spa, SPA_ASYNC_RESILVER);
+       if (rewind_flags & ZPOOL_NEVER_REWIND) {
+               nvlist_free(config);
+               return (load_error);
        }
 
-       error = 0;
-out:
-       spa->spa_minref = refcount_count(&spa->spa_refcount);
-       if (error && error != EBADF)
-               zfs_ereport_post(ereport, spa, NULL, NULL, 0, 0);
-       spa->spa_load_state = SPA_LOAD_NONE;
-       spa->spa_ena = 0;
+       /* Price of rolling back is discarding txgs, including log */
+       if (state == SPA_LOAD_RECOVER)
+               spa_set_log_state(spa, SPA_LOG_CLEAR);
 
-       return (error);
+       spa->spa_load_max_txg = spa->spa_last_ubsync_txg;
+       safe_rewind_txg = spa->spa_last_ubsync_txg - TXG_DEFER_SIZE;
+       min_txg = (rewind_flags & ZPOOL_EXTREME_REWIND) ?
+           TXG_INITIAL : safe_rewind_txg;
+
+       /*
+        * Continue as long as we're finding errors, we're still within
+        * the acceptable rewind range, and we're still finding uberblocks
+        */
+       while (rewind_error && spa->spa_uberblock.ub_txg >= min_txg &&
+           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, mosconfig);
+       }
+
+       if (config)
+               spa_rewind_data_to_nvlist(spa, config);
+
+       spa->spa_extreme_rewind = B_FALSE;
+       spa->spa_load_max_txg = UINT64_MAX;
+
+       if (config && (rewind_error || state != SPA_LOAD_RECOVER))
+               spa_config_set(spa, config);
+
+       return (state == SPA_LOAD_RECOVER ? rewind_error : load_error);
 }
 
 /*
@@ -1624,7 +2198,8 @@ out:
  * ambiguous state.
  */
 static int
-spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t **config)
+spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t *nvpolicy,
+    nvlist_t **config)
 {
        spa_t *spa;
        int error;
@@ -1648,11 +2223,23 @@ spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t **config)
                        mutex_exit(&spa_namespace_lock);
                return (ENOENT);
        }
+
        if (spa->spa_state == POOL_STATE_UNINITIALIZED) {
+               spa_load_state_t state = SPA_LOAD_OPEN;
+               zpool_rewind_policy_t policy;
+
+               zpool_get_rewind_policy(nvpolicy ? nvpolicy : spa->spa_config,
+                   &policy);
+               if (policy.zrp_request & ZPOOL_DO_REWIND)
+                       state = SPA_LOAD_RECOVER;
 
                spa_activate(spa, spa_mode_global);
 
-               error = spa_load(spa, spa->spa_config, SPA_LOAD_OPEN, B_FALSE);
+               if (state != SPA_LOAD_RECOVER)
+                       spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
+
+               error = spa_load_best(spa, state, B_FALSE, policy.zrp_txg,
+                   policy.zrp_request);
 
                if (error == EBADF) {
                        /*
@@ -1677,38 +2264,49 @@ spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t **config)
                         * information: the state of each vdev after the
                         * attempted vdev_open().  Return this to the user.
                         */
-                       if (config != NULL && spa->spa_root_vdev != NULL)
-                               *config = spa_config_generate(spa, NULL, -1ULL,
-                                   B_TRUE);
+                       if (config != NULL && spa->spa_config)
+                               VERIFY(nvlist_dup(spa->spa_config, config,
+                                   KM_SLEEP) == 0);
                        spa_unload(spa);
                        spa_deactivate(spa);
-                       spa->spa_last_open_failed = B_TRUE;
+                       spa->spa_last_open_failed = error;
                        if (locked)
                                mutex_exit(&spa_namespace_lock);
                        *spapp = NULL;
                        return (error);
-               } else {
-                       spa->spa_last_open_failed = B_FALSE;
                }
+
        }
 
        spa_open_ref(spa, tag);
 
-       if (locked)
-               mutex_exit(&spa_namespace_lock);
-
-       *spapp = spa;
 
        if (config != NULL)
                *config = spa_config_generate(spa, NULL, -1ULL, B_TRUE);
 
+       if (locked) {
+               spa->spa_last_open_failed = 0;
+               spa->spa_last_ubsync_txg = 0;
+               spa->spa_load_txg = 0;
+               mutex_exit(&spa_namespace_lock);
+       }
+
+       *spapp = spa;
+
        return (0);
 }
 
 int
+spa_open_rewind(const char *name, spa_t **spapp, void *tag, nvlist_t *policy,
+    nvlist_t **config)
+{
+       return (spa_open_common(name, spapp, tag, policy, config));
+}
+
+int
 spa_open(const char *name, spa_t **spapp, void *tag)
 {
-       return (spa_open_common(name, spapp, tag, NULL));
+       return (spa_open_common(name, spapp, tag, NULL, NULL));
 }
 
 /*
@@ -1779,7 +2377,7 @@ spa_add_spares(spa_t *spa, nvlist_t *config)
                        if (spa_spare_exists(guid, &pool, NULL) &&
                            pool != 0ULL) {
                                VERIFY(nvlist_lookup_uint64_array(
-                                   spares[i], ZPOOL_CONFIG_STATS,
+                                   spares[i], ZPOOL_CONFIG_VDEV_STATS,
                                    (uint64_t **)&vs, &vsc) == 0);
                                vs->vs_state = VDEV_STATE_CANT_OPEN;
                                vs->vs_aux = VDEV_AUX_SPARED;
@@ -1836,7 +2434,8 @@ spa_add_l2cache(spa_t *spa, nvlist_t *config)
                        ASSERT(vd != NULL);
 
                        VERIFY(nvlist_lookup_uint64_array(l2cache[i],
-                           ZPOOL_CONFIG_STATS, (uint64_t **)&vs, &vsc) == 0);
+                           ZPOOL_CONFIG_VDEV_STATS, (uint64_t **)&vs, &vsc)
+                           == 0);
                        vdev_get_stats(vd, vs);
                }
        }
@@ -1849,7 +2448,7 @@ spa_get_stats(const char *name, nvlist_t **config, char *altroot, size_t buflen)
        spa_t *spa;
 
        *config = NULL;
-       error = spa_open_common(name, &spa, FTAG, config);
+       error = spa_open_common(name, &spa, FTAG, NULL, config);
 
        if (spa != NULL) {
                /*
@@ -2093,7 +2692,7 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        uint64_t txg = TXG_INITIAL;
        nvlist_t **spares, **l2cache;
        uint_t nspares, nl2cache;
-       uint64_t version;
+       uint64_t version, obj;
 
        /*
         * If this pool already exists, return failure.
@@ -2109,11 +2708,9 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
         */
        (void) nvlist_lookup_string(props,
            zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
-       spa = spa_add(pool, altroot);
+       spa = spa_add(pool, NULL, altroot);
        spa_activate(spa, spa_mode_global);
 
-       spa->spa_uberblock.ub_txg = txg - 1;
-
        if (props && (error = spa_prop_validate(spa, props))) {
                spa_deactivate(spa);
                spa_remove(spa);
@@ -2125,6 +2722,9 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
            &version) != 0)
                version = SPA_VERSION;
        ASSERT(version <= SPA_VERSION);
+
+       spa->spa_first_txg = txg;
+       spa->spa_uberblock.ub_txg = txg - 1;
        spa->spa_uberblock.ub_version = version;
        spa->spa_ubsync = spa->spa_uberblock;
 
@@ -2200,6 +2800,13 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        spa->spa_dsl_pool = dp = dsl_pool_create(spa, zplprops, txg);
        spa->spa_meta_objset = dp->dp_meta_objset;
 
+       /*
+        * Create DDTs (dedup tables).
+        */
+       ddt_create(spa);
+
+       spa_update_dspace(spa);
+
        tx = dmu_tx_create_assigned(dp, txg);
 
        /*
@@ -2215,6 +2822,12 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
                cmn_err(CE_PANIC, "failed to add pool config");
        }
 
+       if (zap_add(spa->spa_meta_objset,
+           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CREATION_VERSION,
+           sizeof (uint64_t), 1, &version, tx) != 0) {
+               cmn_err(CE_PANIC, "failed to add pool version");
+       }
+
        /* Newly created pools with the right version are always deflated. */
        if (version >= SPA_VERSION_RAIDZ_DEFLATE) {
                spa->spa_deflate = TRUE;
@@ -2226,20 +2839,20 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        }
 
        /*
-        * Create the deferred-free bplist object.  Turn off compression
+        * Create the deferred-free bpobj.  Turn off compression
         * because sync-to-convergence takes longer if the blocksize
         * keeps changing.
         */
-       spa->spa_sync_bplist_obj = bplist_create(spa->spa_meta_objset,
-           1 << 14, tx);
-       dmu_object_set_compress(spa->spa_meta_objset, spa->spa_sync_bplist_obj,
+       obj = bpobj_alloc(spa->spa_meta_objset, 1 << 14, tx);
+       dmu_object_set_compress(spa->spa_meta_objset, obj,
            ZIO_COMPRESS_OFF, tx);
-
        if (zap_add(spa->spa_meta_objset,
-           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPLIST,
-           sizeof (uint64_t), 1, &spa->spa_sync_bplist_obj, tx) != 0) {
-               cmn_err(CE_PANIC, "failed to add bplist");
+           DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_SYNC_BPOBJ,
+           sizeof (uint64_t), 1, &obj, tx) != 0) {
+               cmn_err(CE_PANIC, "failed to add bpobj");
        }
+       VERIFY3U(0, ==, bpobj_open(&spa->spa_deferred_bpobj,
+           spa->spa_meta_objset, obj));
 
        /*
         * Create the pool's history object.
@@ -2254,9 +2867,10 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        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);
+
        if (props != NULL) {
                spa_configfile_set(spa, props, B_FALSE);
-               spa_sync_props(spa, props, CRED(), tx);
+               spa_sync_props(spa, props, tx);
        }
 
        dmu_tx_commit(tx);
@@ -2387,7 +3001,17 @@ spa_import_rootpool(char *devpath, char *devid)
        /*
         * Read the label from the boot device and generate a configuration.
         */
-       if ((config = spa_generate_rootconf(devpath, devid, &guid)) == NULL) {
+       config = spa_generate_rootconf(devpath, devid, &guid);
+#if defined(_OBP) && defined(_KERNEL)
+       if (config == NULL) {
+               if (strstr(devpath, "/iscsi/ssd") != NULL) {
+                       /* iscsi boot */
+                       get_iscsi_bootpath_phy(devpath);
+                       config = spa_generate_rootconf(devpath, devid, &guid);
+               }
+       }
+#endif
+       if (config == NULL) {
                cmn_err(CE_NOTE, "Can not read the pool label from '%s'",
                    devpath);
                return (EIO);
@@ -2406,7 +3030,7 @@ spa_import_rootpool(char *devpath, char *devid)
                spa_remove(spa);
        }
 
-       spa = spa_add(pname, NULL);
+       spa = spa_add(pname, config, NULL);
        spa->spa_is_root = B_TRUE;
        spa->spa_load_verbatim = B_TRUE;
 
@@ -2462,7 +3086,6 @@ spa_import_rootpool(char *devpath, char *devid)
                goto out;
        }
 
-       VERIFY(nvlist_dup(config, &spa->spa_config, 0) == 0);
        error = 0;
        spa_history_log_version(spa, LOG_POOL_IMPORT);
 out:
@@ -2495,12 +3118,10 @@ spa_import_verbatim(const char *pool, nvlist_t *config, nvlist_t *props)
 
        (void) nvlist_lookup_string(props,
            zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
-       spa = spa_add(pool, altroot);
+       spa = spa_add(pool, config, altroot);
 
        spa->spa_load_verbatim = B_TRUE;
 
-       VERIFY(nvlist_dup(config, &spa->spa_config, 0) == 0);
-
        if (props != NULL)
                spa_configfile_set(spa, props, B_FALSE);
 
@@ -2520,6 +3141,8 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
 {
        spa_t *spa;
        char *altroot = NULL;
+       spa_load_state_t state = SPA_LOAD_IMPORT;
+       zpool_rewind_policy_t policy;
        int error;
        nvlist_t *nvroot;
        nvlist_t **spares, **l2cache;
@@ -2529,17 +3152,21 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
         * If a pool with this name exists, return failure.
         */
        mutex_enter(&spa_namespace_lock);
-       if ((spa = spa_lookup(pool)) != NULL) {
+       if (spa_lookup(pool) != NULL) {
                mutex_exit(&spa_namespace_lock);
                return (EEXIST);
        }
 
+       zpool_get_rewind_policy(config, &policy);
+       if (policy.zrp_request & ZPOOL_DO_REWIND)
+               state = SPA_LOAD_RECOVER;
+
        /*
         * Create and initialize the spa structure.
         */
        (void) nvlist_lookup_string(props,
            zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
-       spa = spa_add(pool, altroot);
+       spa = spa_add(pool, config, altroot);
        spa_activate(spa, spa_mode_global);
 
        /*
@@ -2552,7 +3179,16 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
         * because the user-supplied config is actually the one to trust when
         * doing an import.
         */
-       error = spa_load(spa, config, SPA_LOAD_IMPORT, B_TRUE);
+       if (state != SPA_LOAD_RECOVER)
+               spa->spa_last_ubsync_txg = spa->spa_load_txg = 0;
+       error = spa_load_best(spa, state, B_TRUE, policy.zrp_txg,
+           policy.zrp_request);
+
+       /*
+        * Propagate anything learned about failing or best txgs
+        * back to caller
+        */
+       spa_rewind_data_to_nvlist(spa, config);
 
        spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
        /*
@@ -2592,8 +3228,6 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
                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.
@@ -2629,6 +3263,14 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
                spa->spa_l2cache.sav_sync = B_TRUE;
        }
 
+       /*
+        * Check for any removed devices.
+        */
+       if (spa->spa_autoreplace) {
+               spa_aux_check_removed(&spa->spa_spares);
+               spa_aux_check_removed(&spa->spa_l2cache);
+       }
+
        if (spa_writeable(spa)) {
                /*
                 * Update the config cache to include the newly-imported pool.
@@ -2636,6 +3278,8 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
                spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
        }
 
+       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.
@@ -2648,13 +3292,6 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props)
        return (0);
 }
 
-
-/*
- * This (illegal) pool name is used when temporarily importing a spa_t in order
- * to get the vdev stats associated with the imported devices.
- */
-#define        TRYIMPORT_NAME  "$import"
-
 nvlist_t *
 spa_tryimport(nvlist_t *tryconfig)
 {
@@ -2674,7 +3311,7 @@ spa_tryimport(nvlist_t *tryconfig)
         * Create and initialize the spa structure.
         */
        mutex_enter(&spa_namespace_lock);
-       spa = spa_add(TRYIMPORT_NAME, NULL);
+       spa = spa_add(TRYIMPORT_NAME, tryconfig, NULL);
        spa_activate(spa, FREAD);
 
        /*
@@ -2682,7 +3319,7 @@ spa_tryimport(nvlist_t *tryconfig)
         * Pass TRUE for mosconfig because the user-supplied config
         * is actually the one to trust when doing an import.
         */
-       error = spa_load(spa, tryconfig, SPA_LOAD_TRYIMPORT, B_TRUE);
+       error = spa_load(spa, SPA_LOAD_TRYIMPORT, SPA_IMPORT_EXISTING, B_TRUE);
 
        /*
         * If 'tryconfig' was at least parsable, return the current config.
@@ -2827,7 +3464,8 @@ spa_export_common(char *pool, int new_state, nvlist_t **oldconfig,
                if (new_state != POOL_STATE_UNINITIALIZED && !hardforce) {
                        spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
                        spa->spa_state = new_state;
-                       spa->spa_final_txg = spa_last_synced_txg(spa) + 1;
+                       spa->spa_final_txg = spa_last_synced_txg(spa) +
+                           TXG_DEFER_SIZE + 1;
                        vdev_config_dirty(spa->spa_root_vdev);
                        spa_config_exit(spa, SCL_ALL, FTAG);
                }
@@ -2897,7 +3535,7 @@ spa_reset(char *pool)
 int
 spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
 {
-       uint64_t txg;
+       uint64_t txg, id;
        int error;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *vd, *tvd;
@@ -2938,9 +3576,19 @@ spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
         * Transfer each new top-level vdev from vd to rvd.
         */
        for (int c = 0; c < vd->vdev_children; c++) {
+
+               /*
+                * Set the vdev id to the first hole, if one exists.
+                */
+               for (id = 0; id < rvd->vdev_children; id++) {
+                       if (rvd->vdev_child[id]->vdev_ishole) {
+                               vdev_free(rvd->vdev_child[id]);
+                               break;
+                       }
+               }
                tvd = vd->vdev_child[c];
                vdev_remove_child(vd, tvd);
-               tvd->vdev_id = rvd->vdev_children;
+               tvd->vdev_id = id;
                vdev_add_child(rvd, tvd);
                vdev_config_dirty(tvd);
        }
@@ -2997,7 +3645,7 @@ spa_vdev_add(spa_t *spa, nvlist_t *nvroot)
 int
 spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
 {
-       uint64_t txg, open_txg;
+       uint64_t txg, dtl_max_txg;
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *oldvd, *newvd, *newrootvd, *pvd, *tvd;
        vdev_ops_t *pvops;
@@ -3123,6 +3771,7 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
         */
        vdev_remove_child(newrootvd, newvd);
        newvd->vdev_id = pvd->vdev_children;
+       newvd->vdev_crtxg = oldvd->vdev_crtxg;
        vdev_add_child(pvd, newvd);
 
        tvd = newvd->vdev_top;
@@ -3132,13 +3781,14 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
        vdev_config_dirty(tvd);
 
        /*
-        * Set newvd's DTL to [TXG_INITIAL, open_txg].  It will propagate
-        * upward when spa_vdev_exit() calls vdev_dtl_reassess().
+        * Set newvd's DTL to [TXG_INITIAL, dtl_max_txg) so that we account
+        * for any dmu_sync-ed blocks.  It will propagate upward when
+        * spa_vdev_exit() calls vdev_dtl_reassess().
         */
-       open_txg = txg + TXG_CONCURRENT_STATES - 1;
+       dtl_max_txg = txg + TXG_CONCURRENT_STATES;
 
-       vdev_dtl_dirty(newvd, DTL_MISSING,
-           TXG_INITIAL, open_txg - TXG_INITIAL + 1);
+       vdev_dtl_dirty(newvd, DTL_MISSING, TXG_INITIAL,
+           dtl_max_txg - TXG_INITIAL);
 
        if (newvd->vdev_isspare) {
                spa_spare_activate(newvd);
@@ -3154,10 +3804,18 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
         */
        vdev_dirty(tvd, VDD_DTL, newvd, txg);
 
-       (void) spa_vdev_exit(spa, newrootvd, open_txg, 0);
+       /*
+        * Restart the resilver
+        */
+       dsl_resilver_restart(spa->spa_dsl_pool, dtl_max_txg);
+
+       /*
+        * Commit the config
+        */
+       (void) spa_vdev_exit(spa, newrootvd, dtl_max_txg, 0);
 
-       spa_history_internal_log(LOG_POOL_VDEV_ATTACH, spa, NULL,
-           CRED(),  "%s vdev=%s %s vdev=%s",
+       spa_history_log_internal(LOG_POOL_VDEV_ATTACH, spa, NULL,
+           "%s vdev=%s %s vdev=%s",
            replacing && newvd_isspare ? "spare in" :
            replacing ? "replace" : "attach", newvdpath,
            replacing ? "for" : "to", oldvdpath);
@@ -3165,11 +3823,6 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
        spa_strfree(oldvdpath);
        spa_strfree(newvdpath);
 
-       /*
-        * Kick off a resilver to update newvd.
-        */
-       VERIFY3U(spa_scrub(spa, POOL_SCRUB_RESILVER), ==, 0);
-
        return (0);
 }
 
@@ -3188,6 +3841,7 @@ spa_vdev_detach(spa_t *spa, uint64_t guid, uint64_t pguid, int replace_done)
        boolean_t unspare = B_FALSE;
        uint64_t unspare_guid;
        size_t len;
+       char *vdpath;
 
        txg = spa_vdev_enter(spa);
 
@@ -3315,77 +3969,366 @@ spa_vdev_detach(spa_t *spa, uint64_t guid, uint64_t pguid, int replace_done)
                (void) spa_vdev_remove(spa, unspare_guid, B_TRUE);
        }
 
-       /*
-        * If the parent mirror/replacing vdev only has one child,
-        * the parent is no longer needed.  Remove it from the tree.
-        */
-       if (pvd->vdev_children == 1)
-               vdev_remove_parent(cvd);
+       /*
+        * If the parent mirror/replacing vdev only has one child,
+        * the parent is no longer needed.  Remove it from the tree.
+        */
+       if (pvd->vdev_children == 1)
+               vdev_remove_parent(cvd);
+
+       /*
+        * We don't set tvd until now because the parent we just removed
+        * may have been the previous top-level vdev.
+        */
+       tvd = cvd->vdev_top;
+       ASSERT(tvd->vdev_parent == rvd);
+
+       /*
+        * Reevaluate the parent vdev state.
+        */
+       vdev_propagate_state(cvd);
+
+       /*
+        * If the 'autoexpand' property is set on the pool then automatically
+        * try to expand the size of the pool. For example if the device we
+        * just detached was smaller than the others, it may be possible to
+        * add metaslabs (i.e. grow the pool). We need to reopen the vdev
+        * first so that we can obtain the updated sizes of the leaf vdevs.
+        */
+       if (spa->spa_autoexpand) {
+               vdev_reopen(tvd);
+               vdev_expand(tvd, txg);
+       }
+
+       vdev_config_dirty(tvd);
+
+       /*
+        * Mark vd's DTL as dirty in this txg.  vdev_dtl_sync() will see that
+        * vd->vdev_detached is set and free vd's DTL object in syncing context.
+        * But first make sure we're not on any *other* txg's DTL list, to
+        * prevent vd from being accessed after it's freed.
+        */
+       vdpath = spa_strdup(vd->vdev_path);
+       for (int t = 0; t < TXG_SIZE; t++)
+               (void) txg_list_remove_this(&tvd->vdev_dtl_list, vd, t);
+       vd->vdev_detached = B_TRUE;
+       vdev_dirty(tvd, VDD_DTL, vd, txg);
+
+       spa_event_notify(spa, vd, ESC_ZFS_VDEV_REMOVE);
+
+       error = spa_vdev_exit(spa, vd, txg, 0);
+
+       spa_history_log_internal(LOG_POOL_VDEV_DETACH, spa, NULL,
+           "vdev=%s", vdpath);
+       spa_strfree(vdpath);
+
+       /*
+        * If this was the removal of the original device in a hot spare vdev,
+        * then we want to go through and remove the device from the hot spare
+        * list of every other pool.
+        */
+       if (unspare) {
+               spa_t *myspa = spa;
+               spa = NULL;
+               mutex_enter(&spa_namespace_lock);
+               while ((spa = spa_next(spa)) != NULL) {
+                       if (spa->spa_state != POOL_STATE_ACTIVE)
+                               continue;
+                       if (spa == myspa)
+                               continue;
+                       spa_open_ref(spa, FTAG);
+                       mutex_exit(&spa_namespace_lock);
+                       (void) spa_vdev_remove(spa, unspare_guid,
+                           B_TRUE);
+                       mutex_enter(&spa_namespace_lock);
+                       spa_close(spa, FTAG);
+               }
+               mutex_exit(&spa_namespace_lock);
+       }
+
+       return (error);
+}
+
+/*
+ * Split a set of devices from their mirrors, and create a new pool from them.
+ */
+int
+spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
+    nvlist_t *props, boolean_t exp)
+{
+       int error = 0;
+       uint64_t txg, *glist;
+       spa_t *newspa;
+       uint_t c, children, lastlog;
+       nvlist_t **child, *nvl, *tmp;
+       dmu_tx_t *tx;
+       char *altroot = NULL;
+       vdev_t *rvd, **vml = NULL;                      /* vdev modify list */
+       boolean_t activate_slog;
+
+       if (!spa_writeable(spa))
+               return (EROFS);
+
+       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_offline_log(spa);
+       txg = spa_vdev_config_enter(spa);
+
+       if (activate_slog)
+               spa_activate_log(spa);
+
+       if (error != 0)
+               return (spa_vdev_exit(spa, NULL, txg, error));
+
+       /* check new spa name before going any further */
+       if (spa_lookup(newname) != NULL)
+               return (spa_vdev_exit(spa, NULL, txg, EEXIST));
+
+       /*
+        * scan through all the children to ensure they're all mirrors
+        */
+       if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_VDEV_TREE, &nvl) != 0 ||
+           nvlist_lookup_nvlist_array(nvl, ZPOOL_CONFIG_CHILDREN, &child,
+           &children) != 0)
+               return (spa_vdev_exit(spa, NULL, txg, EINVAL));
+
+       /* first, check to ensure we've got the right child count */
+       rvd = spa->spa_root_vdev;
+       lastlog = 0;
+       for (c = 0; c < rvd->vdev_children; c++) {
+               vdev_t *vd = rvd->vdev_child[c];
+
+               /* don't count the holes & logs as children */
+               if (vd->vdev_islog || vd->vdev_ishole) {
+                       if (lastlog == 0)
+                               lastlog = c;
+                       continue;
+               }
+
+               lastlog = 0;
+       }
+       if (children != (lastlog != 0 ? lastlog : rvd->vdev_children))
+               return (spa_vdev_exit(spa, NULL, txg, EINVAL));
+
+       /* next, ensure no spare or cache devices are part of the split */
+       if (nvlist_lookup_nvlist(nvl, ZPOOL_CONFIG_SPARES, &tmp) == 0 ||
+           nvlist_lookup_nvlist(nvl, ZPOOL_CONFIG_L2CACHE, &tmp) == 0)
+               return (spa_vdev_exit(spa, NULL, txg, EINVAL));
+
+       vml = kmem_zalloc(children * sizeof (vdev_t *), KM_SLEEP);
+       glist = kmem_zalloc(children * sizeof (uint64_t), KM_SLEEP);
+
+       /* then, loop over each vdev and validate it */
+       for (c = 0; c < children; c++) {
+               uint64_t is_hole = 0;
+
+               (void) nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_IS_HOLE,
+                   &is_hole);
+
+               if (is_hole != 0) {
+                       if (spa->spa_root_vdev->vdev_child[c]->vdev_ishole ||
+                           spa->spa_root_vdev->vdev_child[c]->vdev_islog) {
+                               continue;
+                       } else {
+                               error = EINVAL;
+                               break;
+                       }
+               }
+
+               /* which disk is going to be split? */
+               if (nvlist_lookup_uint64(child[c], ZPOOL_CONFIG_GUID,
+                   &glist[c]) != 0) {
+                       error = EINVAL;
+                       break;
+               }
+
+               /* look it up in the spa */
+               vml[c] = spa_lookup_by_guid(spa, glist[c], B_FALSE);
+               if (vml[c] == NULL) {
+                       error = ENODEV;
+                       break;
+               }
+
+               /* make sure there's nothing stopping the split */
+               if (vml[c]->vdev_parent->vdev_ops != &vdev_mirror_ops ||
+                   vml[c]->vdev_islog ||
+                   vml[c]->vdev_ishole ||
+                   vml[c]->vdev_isspare ||
+                   vml[c]->vdev_isl2cache ||
+                   !vdev_writeable(vml[c]) ||
+                   vml[c]->vdev_children != 0 ||
+                   vml[c]->vdev_state != VDEV_STATE_HEALTHY ||
+                   c != spa->spa_root_vdev->vdev_child[c]->vdev_id) {
+                       error = EINVAL;
+                       break;
+               }
+
+               if (vdev_dtl_required(vml[c])) {
+                       error = EBUSY;
+                       break;
+               }
+
+               /* we need certain info from the top level */
+               VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_METASLAB_ARRAY,
+                   vml[c]->vdev_top->vdev_ms_array) == 0);
+               VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_METASLAB_SHIFT,
+                   vml[c]->vdev_top->vdev_ms_shift) == 0);
+               VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_ASIZE,
+                   vml[c]->vdev_top->vdev_asize) == 0);
+               VERIFY(nvlist_add_uint64(child[c], ZPOOL_CONFIG_ASHIFT,
+                   vml[c]->vdev_top->vdev_ashift) == 0);
+       }
+
+       if (error != 0) {
+               kmem_free(vml, children * sizeof (vdev_t *));
+               kmem_free(glist, children * sizeof (uint64_t));
+               return (spa_vdev_exit(spa, NULL, txg, error));
+       }
+
+       /* stop writers from using the disks */
+       for (c = 0; c < children; c++) {
+               if (vml[c] != NULL)
+                       vml[c]->vdev_offline = B_TRUE;
+       }
+       vdev_reopen(spa->spa_root_vdev);
 
        /*
-        * We don't set tvd until now because the parent we just removed
-        * may have been the previous top-level vdev.
+        * Temporarily record the splitting vdevs in the spa config.  This
+        * will disappear once the config is regenerated.
         */
-       tvd = cvd->vdev_top;
-       ASSERT(tvd->vdev_parent == rvd);
+       VERIFY(nvlist_alloc(&nvl, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+       VERIFY(nvlist_add_uint64_array(nvl, ZPOOL_CONFIG_SPLIT_LIST,
+           glist, children) == 0);
+       kmem_free(glist, children * sizeof (uint64_t));
 
-       /*
-        * Reevaluate the parent vdev state.
-        */
-       vdev_propagate_state(cvd);
+       mutex_enter(&spa->spa_props_lock);
+       VERIFY(nvlist_add_nvlist(spa->spa_config, ZPOOL_CONFIG_SPLIT,
+           nvl) == 0);
+       mutex_exit(&spa->spa_props_lock);
+       spa->spa_config_splitting = nvl;
+       vdev_config_dirty(spa->spa_root_vdev);
 
-       /*
-        * If the 'autoexpand' property is set on the pool then automatically
-        * try to expand the size of the pool. For example if the device we
-        * just detached was smaller than the others, it may be possible to
-        * add metaslabs (i.e. grow the pool). We need to reopen the vdev
-        * first so that we can obtain the updated sizes of the leaf vdevs.
-        */
-       if (spa->spa_autoexpand) {
-               vdev_reopen(tvd);
-               vdev_expand(tvd, txg);
+       /* configure and create the new pool */
+       VERIFY(nvlist_add_string(config, ZPOOL_CONFIG_POOL_NAME, newname) == 0);
+       VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_STATE,
+           exp ? POOL_STATE_EXPORTED : POOL_STATE_ACTIVE) == 0);
+       VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_VERSION,
+           spa_version(spa)) == 0);
+       VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_TXG,
+           spa->spa_config_txg) == 0);
+       VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_POOL_GUID,
+           spa_generate_guid(NULL)) == 0);
+       (void) nvlist_lookup_string(props,
+           zpool_prop_to_name(ZPOOL_PROP_ALTROOT), &altroot);
+
+       /* add the new pool to the namespace */
+       newspa = spa_add(newname, config, altroot);
+       newspa->spa_config_txg = spa->spa_config_txg;
+       spa_set_log_state(newspa, SPA_LOG_CLEAR);
+
+       /* release the spa config lock, retaining the namespace lock */
+       spa_vdev_config_exit(spa, NULL, txg, 0, FTAG);
+
+       if (zio_injection_enabled)
+               zio_handle_panic_injection(spa, FTAG, 1);
+
+       spa_activate(newspa, spa_mode_global);
+       spa_async_suspend(newspa);
+
+       /* create the new pool from the disks of the original pool */
+       error = spa_load(newspa, SPA_LOAD_IMPORT, SPA_IMPORT_ASSEMBLE, B_TRUE);
+       if (error)
+               goto out;
+
+       /* if that worked, generate a real config for the new pool */
+       if (newspa->spa_root_vdev != NULL) {
+               VERIFY(nvlist_alloc(&newspa->spa_config_splitting,
+                   NV_UNIQUE_NAME, KM_SLEEP) == 0);
+               VERIFY(nvlist_add_uint64(newspa->spa_config_splitting,
+                   ZPOOL_CONFIG_SPLIT_GUID, spa_guid(spa)) == 0);
+               spa_config_set(newspa, spa_config_generate(newspa, NULL, -1ULL,
+                   B_TRUE));
        }
 
-       vdev_config_dirty(tvd);
+       /* set the props */
+       if (props != NULL) {
+               spa_configfile_set(newspa, props, B_FALSE);
+               error = spa_prop_set(newspa, props);
+               if (error)
+                       goto out;
+       }
 
-       /*
-        * Mark vd's DTL as dirty in this txg.  vdev_dtl_sync() will see that
-        * vd->vdev_detached is set and free vd's DTL object in syncing context.
-        * But first make sure we're not on any *other* txg's DTL list, to
-        * prevent vd from being accessed after it's freed.
-        */
-       for (int t = 0; t < TXG_SIZE; t++)
-               (void) txg_list_remove_this(&tvd->vdev_dtl_list, vd, t);
-       vd->vdev_detached = B_TRUE;
-       vdev_dirty(tvd, VDD_DTL, vd, txg);
+       /* flush everything */
+       txg = spa_vdev_config_enter(newspa);
+       vdev_config_dirty(newspa->spa_root_vdev);
+       (void) spa_vdev_config_exit(newspa, NULL, txg, 0, FTAG);
 
-       spa_event_notify(spa, vd, ESC_ZFS_VDEV_REMOVE);
+       if (zio_injection_enabled)
+               zio_handle_panic_injection(spa, FTAG, 2);
 
-       error = spa_vdev_exit(spa, vd, txg, 0);
+       spa_async_resume(newspa);
 
-       /*
-        * If this was the removal of the original device in a hot spare vdev,
-        * then we want to go through and remove the device from the hot spare
-        * list of every other pool.
-        */
-       if (unspare) {
-               spa_t *myspa = spa;
-               spa = NULL;
-               mutex_enter(&spa_namespace_lock);
-               while ((spa = spa_next(spa)) != NULL) {
-                       if (spa->spa_state != POOL_STATE_ACTIVE)
-                               continue;
-                       if (spa == myspa)
-                               continue;
-                       spa_open_ref(spa, FTAG);
-                       mutex_exit(&spa_namespace_lock);
-                       (void) spa_vdev_remove(spa, unspare_guid, B_TRUE);
-                       mutex_enter(&spa_namespace_lock);
-                       spa_close(spa, FTAG);
+       /* finally, update the original pool's config */
+       txg = spa_vdev_config_enter(spa);
+       tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
+       error = dmu_tx_assign(tx, TXG_WAIT);
+       if (error != 0)
+               dmu_tx_abort(tx);
+       for (c = 0; c < children; c++) {
+               if (vml[c] != NULL) {
+                       vdev_split(vml[c]);
+                       if (error == 0)
+                               spa_history_log_internal(LOG_POOL_VDEV_DETACH,
+                                   spa, tx, "vdev=%s",
+                                   vml[c]->vdev_path);
+                       vdev_free(vml[c]);
                }
-               mutex_exit(&spa_namespace_lock);
        }
+       vdev_config_dirty(spa->spa_root_vdev);
+       spa->spa_config_splitting = NULL;
+       nvlist_free(nvl);
+       if (error == 0)
+               dmu_tx_commit(tx);
+       (void) spa_vdev_exit(spa, NULL, txg, 0);
+
+       if (zio_injection_enabled)
+               zio_handle_panic_injection(spa, FTAG, 3);
+
+       /* split is complete; log a history record */
+       spa_history_log_internal(LOG_POOL_SPLIT, newspa, NULL,
+           "split new pool %s from pool %s", newname, spa_name(spa));
+
+       kmem_free(vml, children * sizeof (vdev_t *));
+
+       /* 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);
+
+       return (error);
+
+out:
+       spa_unload(newspa);
+       spa_deactivate(newspa);
+       spa_remove(newspa);
+
+       txg = spa_vdev_config_enter(spa);
+
+       /* re-online all offlined disks */
+       for (c = 0; c < children; c++) {
+               if (vml[c] != NULL)
+                       vml[c]->vdev_offline = B_FALSE;
+       }
+       vdev_reopen(spa->spa_root_vdev);
+
+       nvlist_free(spa->spa_config_splitting);
+       spa->spa_config_splitting = NULL;
+       (void) spa_vdev_exit(spa, NULL, txg, error);
 
+       kmem_free(vml, children * sizeof (vdev_t *));
        return (error);
 }
 
@@ -3431,16 +4374,113 @@ spa_vdev_remove_aux(nvlist_t *config, char *name, nvlist_t **dev, int count,
 }
 
 /*
+ * 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 = ENOTSUP;
+       }
+
+       if (error)
+               return (error);
+
+       /*
+        * The evacuation succeeded.  Remove any remaining MOS metadata
+        * associated with this vdev, and wait for these changes to sync.
+        */
+       ASSERT3U(vd->vdev_stat.vs_alloc, ==, 0);
+       txg = spa_vdev_config_enter(spa);
+       vd->vdev_removing = B_TRUE;
+       vdev_dirty(vd, 0, NULL, 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.
+ */
+
+/*
  * Remove a device from the pool.  Currently, this supports removing only hot
- * spares and level 2 ARC devices.
+ * spares, slogs, and level 2 ARC devices.
  */
 int
 spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
 {
        vdev_t *vd;
+       metaslab_group_t *mg;
        nvlist_t **spares, **l2cache, *nv;
-       uint_t nspares, nl2cache;
        uint64_t txg = 0;
+       uint_t nspares, nl2cache;
        int error = 0;
        boolean_t locked = MUTEX_HELD(&spa_namespace_lock);
 
@@ -3476,6 +4516,49 @@ spa_vdev_remove(spa_t *spa, uint64_t guid, boolean_t unspare)
                    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);
+               ASSERT(vd == vd->vdev_top);
+
+               /*
+                * XXX - Once we have bp-rewrite this should
+                * become the common case.
+                */
+
+               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));
+               }
+
+               /*
+                * Clean up the vdev namespace.
+                */
+               spa_vdev_remove_from_namespace(spa, vd);
+
        } else if (vd != NULL) {
                /*
                 * Normal vdevs cannot be removed (yet).
@@ -3517,6 +4600,7 @@ spa_vdev_resilver_done_hunt(vdev_t *vd)
                newvd = vd->vdev_child[1];
 
                if (vdev_dtl_empty(newvd, DTL_MISSING) &&
+                   vdev_dtl_empty(newvd, DTL_OUTAGE) &&
                    !vdev_dtl_required(oldvd))
                        return (oldvd);
        }
@@ -3530,6 +4614,7 @@ spa_vdev_resilver_done_hunt(vdev_t *vd)
 
                if (newvd->vdev_unspare &&
                    vdev_dtl_empty(newvd, DTL_MISSING) &&
+                   vdev_dtl_empty(newvd, DTL_OUTAGE) &&
                    !vdev_dtl_required(oldvd)) {
                        newvd->vdev_unspare = 0;
                        return (oldvd);
@@ -3576,36 +4661,41 @@ spa_vdev_resilver_done(spa_t *spa)
 }
 
 /*
- * Update the stored path or FRU for this vdev.  Dirty the vdev configuration,
- * relying on spa_vdev_enter/exit() to synchronize the labels and cache.
+ * 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;
-       uint64_t txg;
+       boolean_t sync = B_FALSE;
 
-       txg = spa_vdev_enter(spa);
+       spa_vdev_state_enter(spa, SCL_ALL);
 
        if ((vd = spa_lookup_by_guid(spa, guid, B_TRUE)) == NULL)
-               return (spa_vdev_exit(spa, NULL, txg, ENOENT));
+               return (spa_vdev_state_exit(spa, NULL, ENOENT));
 
        if (!vd->vdev_ops->vdev_op_leaf)
-               return (spa_vdev_exit(spa, NULL, txg, ENOTSUP));
+               return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
 
        if (ispath) {
-               spa_strfree(vd->vdev_path);
-               vd->vdev_path = spa_strdup(value);
+               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)
+               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);
+                       vd->vdev_fru = spa_strdup(value);
+                       sync = B_TRUE;
+               }
        }
 
-       vdev_config_dirty(vd->vdev_top);
-
-       return (spa_vdev_exit(spa, NULL, txg, 0));
+       return (spa_vdev_state_exit(spa, sync ? vd : NULL, 0));
 }
 
 int
@@ -3622,40 +4712,38 @@ spa_vdev_setfru(spa_t *spa, uint64_t guid, const char *newfru)
 
 /*
  * ==========================================================================
- * SPA Scrubbing
+ * SPA Scanning
  * ==========================================================================
  */
 
 int
-spa_scrub(spa_t *spa, pool_scrub_type_t type)
+spa_scan_stop(spa_t *spa)
+{
+       ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);
+       if (dsl_scan_resilvering(spa->spa_dsl_pool))
+               return (EBUSY);
+       return (dsl_scan_cancel(spa->spa_dsl_pool));
+}
+
+int
+spa_scan(spa_t *spa, pool_scan_func_t func)
 {
        ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == 0);
 
-       if ((uint_t)type >= POOL_SCRUB_TYPES)
+       if (func >= POOL_SCAN_FUNCS || func == POOL_SCAN_NONE)
                return (ENOTSUP);
 
        /*
         * If a resilver was requested, but there is no DTL on a
         * writeable leaf device, we have nothing to do.
         */
-       if (type == POOL_SCRUB_RESILVER &&
+       if (func == POOL_SCAN_RESILVER &&
            !vdev_resilver_needed(spa->spa_root_vdev, NULL, NULL)) {
                spa_async_request(spa, SPA_ASYNC_RESILVER_DONE);
                return (0);
        }
 
-       if (type == POOL_SCRUB_EVERYTHING &&
-           spa->spa_dsl_pool->dp_scrub_func != SCRUB_FUNC_NONE &&
-           spa->spa_dsl_pool->dp_scrub_isresilver)
-               return (EBUSY);
-
-       if (type == POOL_SCRUB_EVERYTHING || type == POOL_SCRUB_RESILVER) {
-               return (dsl_pool_scrub_clean(spa->spa_dsl_pool));
-       } else if (type == POOL_SCRUB_NONE) {
-               return (dsl_pool_scrub_cancel(spa->spa_dsl_pool));
-       } else {
-               return (EINVAL);
-       }
+       return (dsl_scan(spa->spa_dsl_pool, func));
 }
 
 /*
@@ -3668,9 +4756,20 @@ static void
 spa_async_remove(spa_t *spa, vdev_t *vd)
 {
        if (vd->vdev_remove_wanted) {
-               vd->vdev_remove_wanted = 0;
+               vd->vdev_remove_wanted = B_FALSE;
+               vd->vdev_delayed_close = B_FALSE;
                vdev_set_state(vd, B_FALSE, VDEV_STATE_REMOVED, VDEV_AUX_NONE);
-               vdev_clear(spa, vd);
+
+               /*
+                * We want to clear the stats, but we don't want to do a full
+                * vdev_clear() as that will cause us to throw away
+                * degraded/faulted state as well as attempt to reopen the
+                * device, all of which is a waste.
+                */
+               vd->vdev_stat.vs_read_errors = 0;
+               vd->vdev_stat.vs_write_errors = 0;
+               vd->vdev_stat.vs_checksum_errors = 0;
+
                vdev_state_dirty(vd->vdev_top);
        }
 
@@ -3682,7 +4781,7 @@ static void
 spa_async_probe(spa_t *spa, vdev_t *vd)
 {
        if (vd->vdev_probe_wanted) {
-               vd->vdev_probe_wanted = 0;
+               vd->vdev_probe_wanted = B_FALSE;
                vdev_reopen(vd);        /* vdev_open() does the actual probe */
        }
 
@@ -3737,24 +4836,23 @@ spa_async_thread(spa_t *spa)
         * See if the config needs to be updated.
         */
        if (tasks & SPA_ASYNC_CONFIG_UPDATE) {
-               uint64_t oldsz, space_update;
+               uint64_t old_space, new_space;
 
                mutex_enter(&spa_namespace_lock);
-               oldsz = spa_get_space(spa);
+               old_space = metaslab_class_get_space(spa_normal_class(spa));
                spa_config_update(spa, SPA_CONFIG_UPDATE_POOL);
-               space_update = spa_get_space(spa) - oldsz;
+               new_space = metaslab_class_get_space(spa_normal_class(spa));
                mutex_exit(&spa_namespace_lock);
 
                /*
                 * If the pool grew as a result of the config update,
                 * then log an internal history event.
                 */
-               if (space_update) {
-                       spa_history_internal_log(LOG_POOL_VDEV_ONLINE,
-                           spa, NULL, CRED(),
+               if (new_space != old_space) {
+                       spa_history_log_internal(LOG_POOL_VDEV_ONLINE,
+                           spa, NULL,
                            "pool '%s' size: %llu(+%llu)",
-                           spa_name(spa), spa_get_space(spa),
-                           space_update);
+                           spa_name(spa), new_space, new_space - old_space);
                }
        }
 
@@ -3762,7 +4860,7 @@ spa_async_thread(spa_t *spa)
         * See if any devices need to be marked REMOVED.
         */
        if (tasks & SPA_ASYNC_REMOVE) {
-               spa_vdev_state_enter(spa);
+               spa_vdev_state_enter(spa, SCL_NONE);
                spa_async_remove(spa, spa->spa_root_vdev);
                for (int i = 0; i < spa->spa_l2cache.sav_count; i++)
                        spa_async_remove(spa, spa->spa_l2cache.sav_vdevs[i]);
@@ -3781,7 +4879,7 @@ spa_async_thread(spa_t *spa)
         * See if any devices need to be probed.
         */
        if (tasks & SPA_ASYNC_PROBE) {
-               spa_vdev_state_enter(spa);
+               spa_vdev_state_enter(spa, SCL_NONE);
                spa_async_probe(spa, spa->spa_root_vdev);
                (void) spa_vdev_state_exit(spa, NULL, 0);
        }
@@ -3796,7 +4894,7 @@ spa_async_thread(spa_t *spa)
         * Kick off a resilver.
         */
        if (tasks & SPA_ASYNC_RESILVER)
-               VERIFY(spa_scrub(spa, POOL_SCRUB_RESILVER) == 0);
+               dsl_resilver_restart(spa->spa_dsl_pool, 0);
 
        /*
         * Let the world know that we're done.
@@ -3842,6 +4940,7 @@ spa_async_dispatch(spa_t *spa)
 void
 spa_async_request(spa_t *spa, int task)
 {
+       zfs_dbgmsg("spa=%s async request task=%u", spa->spa_name, task);
        mutex_enter(&spa->spa_async_lock);
        spa->spa_async_tasks |= task;
        mutex_exit(&spa->spa_async_lock);
@@ -3853,37 +4952,22 @@ spa_async_request(spa_t *spa, int task)
  * ==========================================================================
  */
 
-static void
-spa_sync_deferred_frees(spa_t *spa, uint64_t txg)
+static int
+bpobj_enqueue_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
 {
-       bplist_t *bpl = &spa->spa_sync_bplist;
-       dmu_tx_t *tx;
-       blkptr_t blk;
-       uint64_t itor = 0;
-       zio_t *zio;
-       int error;
-       uint8_t c = 1;
-
-       zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
-
-       while (bplist_iterate(bpl, &itor, &blk) == 0) {
-               ASSERT(blk.blk_birth < txg);
-               zio_nowait(zio_free(zio, spa, txg, &blk, NULL, NULL,
-                   ZIO_FLAG_MUSTSUCCEED));
-       }
-
-       error = zio_wait(zio);
-       ASSERT3U(error, ==, 0);
+       bpobj_t *bpo = arg;
+       bpobj_enqueue(bpo, bp, tx);
+       return (0);
+}
 
-       tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
-       bplist_vacate(bpl, tx);
+static int
+spa_free_sync_cb(void *arg, const blkptr_t *bp, dmu_tx_t *tx)
+{
+       zio_t *zio = arg;
 
-       /*
-        * Pre-dirty the first block so we sync to convergence faster.
-        * (Usually only the first block is needed.)
-        */
-       dmu_write(spa->spa_meta_objset, spa->spa_sync_bplist_obj, 0, 1, &c, tx);
-       dmu_tx_commit(tx);
+       zio_nowait(zio_free_sync(zio, zio->io_spa, dmu_tx_get_txg(tx), bp,
+           zio->io_flags));
+       return (0);
 }
 
 static void
@@ -3950,7 +5034,7 @@ spa_sync_aux_dev(spa_t *spa, spa_aux_vdev_t *sav, dmu_tx_t *tx,
                list = kmem_alloc(sav->sav_count * sizeof (void *), KM_SLEEP);
                for (i = 0; i < sav->sav_count; i++)
                        list[i] = vdev_config_generate(spa, sav->sav_vdevs[i],
-                           B_FALSE, B_FALSE, B_TRUE);
+                           B_FALSE, VDEV_CONFIG_L2CACHE);
                VERIFY(nvlist_add_nvlist_array(nvroot, config, list,
                    sav->sav_count) == 0);
                for (i = 0; i < sav->sav_count; i++)
@@ -3990,7 +5074,7 @@ spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
  * Set zpool properties.
  */
 static void
-spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
+spa_sync_props(void *arg1, void *arg2, dmu_tx_t *tx)
 {
        spa_t *spa = arg1;
        objset_t *mos = spa->spa_meta_objset;
@@ -4041,8 +5125,6 @@ spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
                         * Set pool property values in the poolprops mos object.
                         */
                        if (spa->spa_pool_props_object == 0) {
-                               objset_t *mos = spa->spa_meta_objset;
-
                                VERIFY((spa->spa_pool_props_object =
                                    zap_create(mos, DMU_OT_POOL_PROPS,
                                    DMU_OT_NONE, 0, tx)) > 0);
@@ -4091,7 +5173,12 @@ spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
                                break;
                        case ZPOOL_PROP_AUTOEXPAND:
                                spa->spa_autoexpand = intval;
-                               spa_async_request(spa, SPA_ASYNC_AUTOEXPAND);
+                               if (tx->tx_txg != TXG_INITIAL)
+                                       spa_async_request(spa,
+                                           SPA_ASYNC_AUTOEXPAND);
+                               break;
+                       case ZPOOL_PROP_DEDUPDITTO:
+                               spa->spa_dedup_ditto = intval;
                                break;
                        default:
                                break;
@@ -4101,8 +5188,8 @@ spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
                /* log internal history if this is not a zpool create */
                if (spa_version(spa) >= SPA_VERSION_ZPOOL_HISTORY &&
                    tx->tx_txg != TXG_INITIAL) {
-                       spa_history_internal_log(LOG_POOL_PROPSET,
-                           spa, tx, cr, "%s %lld %s",
+                       spa_history_log_internal(LOG_POOL_PROPSET,
+                           spa, tx, "%s %lld %s",
                            nvpair_name(elem), intval, spa_name(spa));
                }
        }
@@ -4111,6 +5198,42 @@ spa_sync_props(void *arg1, void *arg2, cred_t *cr, dmu_tx_t *tx)
 }
 
 /*
+ * Perform one-time upgrade on-disk changes.  spa_version() does not
+ * reflect the new version this txg, so there must be no changes this
+ * txg to anything that the upgrade code depends on after it executes.
+ * Therefore this must be called after dsl_pool_sync() does the sync
+ * tasks.
+ */
+static void
+spa_sync_upgrades(spa_t *spa, dmu_tx_t *tx)
+{
+       dsl_pool_t *dp = spa->spa_dsl_pool;
+
+       ASSERT(spa->spa_sync_pass == 1);
+
+       if (spa->spa_ubsync.ub_version < SPA_VERSION_ORIGIN &&
+           spa->spa_uberblock.ub_version >= SPA_VERSION_ORIGIN) {
+               dsl_pool_create_origin(dp, tx);
+
+               /* Keeping the origin open increases spa_minref */
+               spa->spa_minref += 3;
+       }
+
+       if (spa->spa_ubsync.ub_version < SPA_VERSION_NEXT_CLONES &&
+           spa->spa_uberblock.ub_version >= SPA_VERSION_NEXT_CLONES) {
+               dsl_pool_upgrade_clones(dp, tx);
+       }
+
+       if (spa->spa_ubsync.ub_version < SPA_VERSION_DIR_CLONES &&
+           spa->spa_uberblock.ub_version >= SPA_VERSION_DIR_CLONES) {
+               dsl_pool_upgrade_dir_clones(dp, tx);
+
+               /* Keeping the freedir open increases spa_minref */
+               spa->spa_minref += 3;
+       }
+}
+
+/*
  * Sync the specified transaction group.  New blocks may be dirtied as
  * part of the process, so we iterate until it converges.
  */
@@ -4119,11 +5242,11 @@ spa_sync(spa_t *spa, uint64_t txg)
 {
        dsl_pool_t *dp = spa->spa_dsl_pool;
        objset_t *mos = spa->spa_meta_objset;
-       bplist_t *bpl = &spa->spa_sync_bplist;
+       bpobj_t *defer_bpo = &spa->spa_deferred_bpobj;
+       bplist_t *free_bpl = &spa->spa_free_bplist[txg & TXG_MASK];
        vdev_t *rvd = spa->spa_root_vdev;
        vdev_t *vd;
        dmu_tx_t *tx;
-       int dirty_vdevs;
        int error;
 
        /*
@@ -4158,8 +5281,6 @@ spa_sync(spa_t *spa, uint64_t txg)
        }
        spa_config_exit(spa, SCL_STATE, FTAG);
 
-       VERIFY(0 == bplist_open(bpl, mos, spa->spa_sync_bplist_obj));
-
        tx = dmu_tx_create_assigned(dp, txg);
 
        /*
@@ -4183,34 +5304,29 @@ spa_sync(spa_t *spa, uint64_t txg)
                }
        }
 
-       if (spa->spa_ubsync.ub_version < SPA_VERSION_ORIGIN &&
-           spa->spa_uberblock.ub_version >= SPA_VERSION_ORIGIN) {
-               dsl_pool_create_origin(dp, tx);
-
-               /* Keeping the origin open increases spa_minref */
-               spa->spa_minref += 3;
-       }
-
-       if (spa->spa_ubsync.ub_version < SPA_VERSION_NEXT_CLONES &&
-           spa->spa_uberblock.ub_version >= SPA_VERSION_NEXT_CLONES) {
-               dsl_pool_upgrade_clones(dp, tx);
-       }
-
        /*
-        * If anything has changed in this txg, push the deferred frees
-        * from the previous txg.  If not, leave them alone so that we
-        * don't generate work on an otherwise idle system.
+        * If anything has changed in this txg, or if someone is waiting
+        * for this txg to sync (eg, spa_vdev_remove()), push the
+        * deferred frees from the previous txg.  If not, leave them
+        * alone so that we don't generate work on an otherwise idle
+        * system.
         */
        if (!txg_list_empty(&dp->dp_dirty_datasets, txg) ||
            !txg_list_empty(&dp->dp_dirty_dirs, txg) ||
-           !txg_list_empty(&dp->dp_sync_tasks, txg))
-               spa_sync_deferred_frees(spa, txg);
+           !txg_list_empty(&dp->dp_sync_tasks, txg) ||
+           ((dsl_scan_active(dp->dp_scan) ||
+           txg_sync_waiting(dp)) && !spa_shutting_down(spa))) {
+               zio_t *zio = zio_root(spa, NULL, NULL, 0);
+               VERIFY3U(bpobj_iterate(defer_bpo,
+                   spa_free_sync_cb, zio, tx), ==, 0);
+               VERIFY3U(zio_wait(zio), ==, 0);
+       }
 
        /*
         * Iterate to convergence.
         */
        do {
-               spa->spa_sync_pass++;
+               int pass = ++spa->spa_sync_pass;
 
                spa_sync_config_object(spa, tx);
                spa_sync_aux_dev(spa, &spa->spa_spares, tx,
@@ -4220,18 +5336,26 @@ spa_sync(spa_t *spa, uint64_t txg)
                spa_errlog_sync(spa, txg);
                dsl_pool_sync(dp, txg);
 
-               dirty_vdevs = 0;
-               while (vd = txg_list_remove(&spa->spa_vdev_txg_list, txg)) {
-                       vdev_sync(vd, txg);
-                       dirty_vdevs++;
+               if (pass <= SYNC_PASS_DEFERRED_FREE) {
+                       zio_t *zio = zio_root(spa, NULL, NULL, 0);
+                       bplist_iterate(free_bpl, spa_free_sync_cb,
+                           zio, tx);
+                       VERIFY(zio_wait(zio) == 0);
+               } else {
+                       bplist_iterate(free_bpl, bpobj_enqueue_cb,
+                           defer_bpo, tx);
                }
 
-               bplist_sync(bpl, tx);
-       } while (dirty_vdevs);
+               ddt_sync(spa, txg);
+               dsl_scan_sync(dp, tx);
 
-       bplist_close(bpl);
+               while (vd = txg_list_remove(&spa->spa_vdev_txg_list, txg))
+                       vdev_sync(vd, txg);
+
+               if (pass == 1)
+                       spa_sync_upgrades(spa, tx);
 
-       dprintf("txg %llu passes %d\n", txg, spa->spa_sync_pass);
+       } while (dmu_objset_is_dirty(mos, txg));
 
        /*
         * Rewrite the vdev configuration (which includes the uberblock)
@@ -4302,10 +5426,7 @@ spa_sync(spa_t *spa, uint64_t txg)
 
        spa->spa_ubsync = spa->spa_uberblock;
 
-       /*
-        * Clean up the ZIL records for the synced txg.
-        */
-       dsl_pool_zil_clean(dp);
+       dsl_pool_sync_done(dp, txg);
 
        /*
         * Update usable space statistics.
@@ -4313,6 +5434,8 @@ spa_sync(spa_t *spa, uint64_t txg)
        while (vd = txg_list_remove(&spa->spa_vdev_txg_list, TXG_CLEAN(txg)))
                vdev_sync_done(vd, txg);
 
+       spa_update_dspace(spa);
+
        /*
         * It had better be the case that we didn't dirty anything
         * since vdev_config_sync().
@@ -4320,10 +5443,13 @@ spa_sync(spa_t *spa, uint64_t txg)
        ASSERT(txg_list_empty(&dp->dp_dirty_datasets, txg));
        ASSERT(txg_list_empty(&dp->dp_dirty_dirs, txg));
        ASSERT(txg_list_empty(&spa->spa_vdev_txg_list, txg));
-       ASSERT(bpl->bpl_queue == NULL);
+
+       spa->spa_sync_pass = 0;
 
        spa_config_exit(spa, SCL_CONFIG, FTAG);
 
+       spa_handle_ignored_writes(spa);
+
        /*
         * If any async tasks have been requested, kick them off.
         */