Illumos #3498 panic in arc_read()
[zfs.git] / module / zfs / spa.c
index 57d25c3..e986e92 100644 (file)
@@ -21,6 +21,8 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /*
@@ -61,6 +63,7 @@
 #include <sys/spa_boot.h>
 #include <sys/zfs_ioctl.h>
 #include <sys/dsl_scan.h>
+#include <sys/zfeature.h>
 
 #ifdef _KERNEL
 #include <sys/bootprops.h>
 #include "zfs_comutil.h"
 
 typedef enum zti_modes {
-       zti_mode_fixed,                 /* value is # of threads (min 1) */
-       zti_mode_online_percent,        /* value is % of online CPUs */
-       zti_mode_batch,                 /* cpu-intensive; value is ignored */
-       zti_mode_null,                  /* don't create a taskq */
-       zti_nmodes
+       ZTI_MODE_FIXED,                 /* value is # of threads (min 1) */
+       ZTI_MODE_ONLINE_PERCENT,        /* value is % of online CPUs */
+       ZTI_MODE_BATCH,                 /* cpu-intensive; value is ignored */
+       ZTI_MODE_NULL,                  /* don't create a taskq */
+       ZTI_NMODES
 } zti_modes_t;
 
-#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_P(n, q)     { ZTI_MODE_FIXED, (n), (q) }
+#define        ZTI_PCT(n)      { ZTI_MODE_ONLINE_PERCENT, (n), 1 }
+#define        ZTI_BATCH       { ZTI_MODE_BATCH, 0, 1 }
+#define        ZTI_NULL        { ZTI_MODE_NULL, 0, 0 }
 
-#define        ZTI_ONE         ZTI_FIX(1)
+#define        ZTI_N(n)        ZTI_P(n, 1)
+#define        ZTI_ONE         ZTI_N(1)
 
 typedef struct zio_taskq_info {
-       enum zti_modes zti_mode;
+       zti_modes_t zti_mode;
        uint_t zti_value;
+       uint_t zti_count;
 } zio_taskq_info_t;
 
 static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
@@ -99,20 +104,36 @@ static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
 };
 
 /*
- * Define the taskq threads for the following I/O types:
- *     NULL, READ, WRITE, FREE, CLAIM, and IOCTL
+ * This table defines the taskq settings for each ZFS I/O type. When
+ * initializing a pool, we use this table to create an appropriately sized
+ * taskq. Some operations are low volume and therefore have a small, static
+ * number of threads assigned to their taskqs using the ZTI_N(#) or ZTI_ONE
+ * macros. Other operations process a large amount of data; the ZTI_BATCH
+ * macro causes us to create a taskq oriented for throughput. Some operations
+ * are so high frequency and short-lived that the taskq itself can become a a
+ * point of lock contention. The ZTI_P(#, #) macro indicates that we need an
+ * additional degree of parallelism specified by the number of threads per-
+ * taskq and the number of taskqs; when dispatching an event in this case, the
+ * particular taskq is chosen at random.
+ *
+ * The different taskq priorities are to handle the different contexts (issue
+ * and interrupt) and then to reserve threads for ZIO_PRIORITY_NOW I/Os that
+ * need to be handled with minimum delay.
  */
 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(16),    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 },
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL }, /* NULL */
+       { ZTI_N(8),     ZTI_NULL,       ZTI_BATCH,      ZTI_NULL }, /* READ */
+       { ZTI_BATCH,    ZTI_N(5),       ZTI_N(16),      ZTI_N(5) }, /* WRITE */
+       { ZTI_P(4, 8),  ZTI_NULL,       ZTI_ONE,        ZTI_NULL }, /* FREE */
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL }, /* CLAIM */
+       { ZTI_ONE,      ZTI_NULL,       ZTI_ONE,        ZTI_NULL }, /* IOCTL */
 };
 
+static dsl_syncfunc_t spa_sync_version;
 static dsl_syncfunc_t spa_sync_props;
+static dsl_checkfunc_t spa_change_guid_check;
+static dsl_syncfunc_t spa_change_guid_sync;
 static boolean_t spa_has_active_shared_spare(spa_t *spa);
 static inline 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,
@@ -148,7 +169,7 @@ spa_prop_add_list(nvlist_t *nvl, zpool_prop_t prop, char *strval,
        const char *propname = zpool_prop_to_name(prop);
        nvlist_t *propval;
 
-       VERIFY(nvlist_alloc(&propval, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+       VERIFY(nvlist_alloc(&propval, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
        VERIFY(nvlist_add_uint64(propval, ZPROP_SOURCE, src) == 0);
 
        if (strval != NULL)
@@ -166,15 +187,19 @@ spa_prop_add_list(nvlist_t *nvl, zpool_prop_t prop, char *strval,
 static void
 spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
 {
+       vdev_t *rvd = spa->spa_root_vdev;
+       dsl_pool_t *pool = spa->spa_dsl_pool;
        uint64_t size;
        uint64_t alloc;
+       uint64_t space;
        uint64_t cap, version;
        zprop_source_t src = ZPROP_SRC_NONE;
        spa_config_dirent_t *dp;
+       int c;
 
        ASSERT(MUTEX_HELD(&spa->spa_props_lock));
 
-       if (spa->spa_root_vdev != NULL) {
+       if (rvd != NULL) {
                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);
@@ -182,6 +207,15 @@ spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
                spa_prop_add_list(*nvp, ZPOOL_PROP_ALLOCATED, NULL, alloc, src);
                spa_prop_add_list(*nvp, ZPOOL_PROP_FREE, NULL,
                    size - alloc, src);
+
+               space = 0;
+               for (c = 0; c < rvd->vdev_children; c++) {
+                       vdev_t *tvd = rvd->vdev_child[c];
+                       space += tvd->vdev_max_asize - tvd->vdev_asize;
+               }
+               spa_prop_add_list(*nvp, ZPOOL_PROP_EXPANDSZ, NULL, space,
+                   src);
+
                spa_prop_add_list(*nvp, ZPOOL_PROP_READONLY, NULL,
                    (spa_mode(spa) == FREAD), src);
 
@@ -192,7 +226,7 @@ spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
                    ddt_get_pool_dedup_ratio(spa), src);
 
                spa_prop_add_list(*nvp, ZPOOL_PROP_HEALTH, NULL,
-                   spa->spa_root_vdev->vdev_state, src);
+                   rvd->vdev_state, src);
 
                version = spa_version(spa);
                if (version == zpool_prop_default_numeric(ZPOOL_PROP_VERSION))
@@ -202,8 +236,29 @@ spa_prop_get_config(spa_t *spa, nvlist_t **nvp)
                spa_prop_add_list(*nvp, ZPOOL_PROP_VERSION, NULL, version, src);
        }
 
+       if (pool != NULL) {
+               dsl_dir_t *freedir = pool->dp_free_dir;
+
+               /*
+                * The $FREE directory was introduced in SPA_VERSION_DEADLISTS,
+                * when opening pools before this version freedir will be NULL.
+                */
+               if (freedir != NULL) {
+                       spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING, NULL,
+                           freedir->dd_phys->dd_used_bytes, src);
+               } else {
+                       spa_prop_add_list(*nvp, ZPOOL_PROP_FREEING,
+                           NULL, 0, src);
+               }
+       }
+
        spa_prop_add_list(*nvp, ZPOOL_PROP_GUID, NULL, spa_guid(spa), src);
 
+       if (spa->spa_comment != NULL) {
+               spa_prop_add_list(*nvp, ZPOOL_PROP_COMMENT, spa->spa_comment,
+                   0, ZPROP_SRC_LOCAL);
+       }
+
        if (spa->spa_root != NULL)
                spa_prop_add_list(*nvp, ZPOOL_PROP_ALTROOT, spa->spa_root,
                    0, ZPROP_SRC_LOCAL);
@@ -230,7 +285,7 @@ spa_prop_get(spa_t *spa, nvlist_t **nvp)
        zap_attribute_t za;
        int err;
 
-       err = nvlist_alloc(nvp, NV_UNIQUE_NAME, KM_SLEEP);
+       err = nvlist_alloc(nvp, NV_UNIQUE_NAME, KM_PUSHPAGE);
        if (err)
                return err;
 
@@ -282,7 +337,7 @@ spa_prop_get(spa_t *spa, nvlist_t **nvp)
 
                                strval = kmem_alloc(
                                    MAXNAMELEN + strlen(MOS_DIR_NAME) + 1,
-                                   KM_SLEEP);
+                                   KM_PUSHPAGE);
                                dsl_dataset_name(ds, strval);
                                dsl_dataset_rele(ds, FTAG);
                                rw_exit(&dp->dp_config_rwlock);
@@ -301,7 +356,7 @@ spa_prop_get(spa_t *spa, nvlist_t **nvp)
 
                case 1:
                        /* string property */
-                       strval = kmem_alloc(za.za_num_integers, KM_SLEEP);
+                       strval = kmem_alloc(za.za_num_integers, KM_PUSHPAGE);
                        err = zap_lookup(mos, spa->spa_pool_props_object,
                            za.za_name, 1, za.za_num_integers, strval);
                        if (err) {
@@ -338,25 +393,55 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
        nvpair_t *elem;
        int error = 0, reset_bootfs = 0;
        uint64_t objnum = 0;
+       boolean_t has_feature = B_FALSE;
 
        elem = NULL;
        while ((elem = nvlist_next_nvpair(props, elem)) != NULL) {
-               zpool_prop_t prop;
-               char *propname, *strval;
                uint64_t intval;
-               objset_t *os;
-               char *slash;
+               char *strval, *slash, *check, *fname;
+               const char *propname = nvpair_name(elem);
+               zpool_prop_t prop = zpool_name_to_prop(propname);
 
-               propname = nvpair_name(elem);
+               switch ((int)prop) {
+               case ZPROP_INVAL:
+                       if (!zpool_prop_feature(propname)) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       /*
+                        * Sanitize the input.
+                        */
+                       if (nvpair_type(elem) != DATA_TYPE_UINT64) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       if (nvpair_value_uint64(elem, &intval) != 0) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       if (intval != 0) {
+                               error = EINVAL;
+                               break;
+                       }
+
+                       fname = strchr(propname, '@') + 1;
+                       if (zfeature_lookup_name(fname, NULL) != 0) {
+                               error = EINVAL;
+                               break;
+                       }
 
-               if ((prop = zpool_name_to_prop(propname)) == ZPROP_INVAL)
-                       return (EINVAL);
+                       has_feature = B_TRUE;
+                       break;
 
-               switch (prop) {
                case ZPOOL_PROP_VERSION:
                        error = nvpair_value_uint64(elem, &intval);
                        if (!error &&
-                           (intval < spa_version(spa) || intval > SPA_VERSION))
+                           (intval < spa_version(spa) ||
+                           intval > SPA_VERSION_BEFORE_FEATURES ||
+                           has_feature))
                                error = EINVAL;
                        break;
 
@@ -393,6 +478,7 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
                        error = nvpair_value_string(elem, &strval);
 
                        if (!error) {
+                               objset_t *os;
                                uint64_t compress;
 
                                if (strval == NULL || strval[0] == '\0') {
@@ -465,6 +551,20 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
                                error = EINVAL;
                        break;
 
+               case ZPOOL_PROP_COMMENT:
+                       if ((error = nvpair_value_string(elem, &strval)) != 0)
+                               break;
+                       for (check = strval; *check != '\0'; check++) {
+                               if (!isprint(*check)) {
+                                       error = EINVAL;
+                                       break;
+                               }
+                               check++;
+                       }
+                       if (strlen(strval) > ZPROP_MAX_COMMENT)
+                               error = E2BIG;
+                       break;
+
                case ZPOOL_PROP_DEDUPDITTO:
                        if (spa_version(spa) < SPA_VERSION_DEDUP)
                                error = ENOTSUP;
@@ -507,7 +607,7 @@ spa_configfile_set(spa_t *spa, nvlist_t *nvp, boolean_t need_sync)
                return;
 
        dp = kmem_alloc(sizeof (spa_config_dirent_t),
-           KM_SLEEP);
+           KM_PUSHPAGE);
 
        if (cachefile[0] == '\0')
                dp->scd_path = spa_strdup(spa_config_path);
@@ -525,33 +625,58 @@ int
 spa_prop_set(spa_t *spa, nvlist_t *nvp)
 {
        int error;
-       nvpair_t *elem;
+       nvpair_t *elem = NULL;
        boolean_t need_sync = B_FALSE;
-       zpool_prop_t prop;
 
        if ((error = spa_prop_validate(spa, nvp)) != 0)
                return (error);
 
-       elem = NULL;
        while ((elem = nvlist_next_nvpair(nvp, elem)) != NULL) {
-               if ((prop = zpool_name_to_prop(
-                   nvpair_name(elem))) == ZPROP_INVAL)
-                       return (EINVAL);
+               zpool_prop_t prop = zpool_name_to_prop(nvpair_name(elem));
 
                if (prop == ZPOOL_PROP_CACHEFILE ||
                    prop == ZPOOL_PROP_ALTROOT ||
                    prop == ZPOOL_PROP_READONLY)
                        continue;
 
+               if (prop == ZPOOL_PROP_VERSION || prop == ZPROP_INVAL) {
+                       uint64_t ver;
+
+                       if (prop == ZPOOL_PROP_VERSION) {
+                               VERIFY(nvpair_value_uint64(elem, &ver) == 0);
+                       } else {
+                               ASSERT(zpool_prop_feature(nvpair_name(elem)));
+                               ver = SPA_VERSION_FEATURES;
+                               need_sync = B_TRUE;
+                       }
+
+                       /* Save time if the version is already set. */
+                       if (ver == spa_version(spa))
+                               continue;
+
+                       /*
+                        * In addition to the pool directory object, we might
+                        * create the pool properties object, the features for
+                        * read object, the features for write object, or the
+                        * feature descriptions object.
+                        */
+                       error = dsl_sync_task_do(spa_get_dsl(spa), NULL,
+                           spa_sync_version, spa, &ver, 6);
+                       if (error)
+                               return (error);
+                       continue;
+               }
+
                need_sync = B_TRUE;
                break;
        }
 
-       if (need_sync)
+       if (need_sync) {
                return (dsl_sync_task_do(spa_get_dsl(spa), NULL, spa_sync_props,
-                   spa, nvp, 3));
-       else
-               return (0);
+                   spa, nvp, 6));
+       }
+
+       return (0);
 }
 
 /*
@@ -568,6 +693,78 @@ spa_prop_clear_bootfs(spa_t *spa, uint64_t dsobj, dmu_tx_t *tx)
        }
 }
 
+/*ARGSUSED*/
+static int
+spa_change_guid_check(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       spa_t *spa = arg1;
+       vdev_t *rvd = spa->spa_root_vdev;
+       uint64_t vdev_state;
+       ASSERTV(uint64_t *newguid = arg2);
+
+       spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
+       vdev_state = rvd->vdev_state;
+       spa_config_exit(spa, SCL_STATE, FTAG);
+
+       if (vdev_state != VDEV_STATE_HEALTHY)
+               return (ENXIO);
+
+       ASSERT3U(spa_guid(spa), !=, *newguid);
+
+       return (0);
+}
+
+static void
+spa_change_guid_sync(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       spa_t *spa = arg1;
+       uint64_t *newguid = arg2;
+       uint64_t oldguid;
+       vdev_t *rvd = spa->spa_root_vdev;
+
+       oldguid = spa_guid(spa);
+
+       spa_config_enter(spa, SCL_STATE, FTAG, RW_READER);
+       rvd->vdev_guid = *newguid;
+       rvd->vdev_guid_sum += (*newguid - oldguid);
+       vdev_config_dirty(rvd);
+       spa_config_exit(spa, SCL_STATE, FTAG);
+
+       spa_history_log_internal(LOG_POOL_GUID_CHANGE, spa, tx,
+           "old=%lld new=%lld", oldguid, *newguid);
+}
+
+/*
+ * Change the GUID for the pool.  This is done so that we can later
+ * re-import a pool built from a clone of our own vdevs.  We will modify
+ * the root vdev's guid, our own pool guid, and then mark all of our
+ * vdevs dirty.  Note that we must make sure that all our vdevs are
+ * online when we do this, or else any vdevs that weren't present
+ * would be orphaned from our pool.  We are also going to issue a
+ * sysevent to update any watchers.
+ */
+int
+spa_change_guid(spa_t *spa)
+{
+       int error;
+       uint64_t guid;
+
+       mutex_enter(&spa_namespace_lock);
+       guid = spa_generate_guid(NULL);
+
+       error = dsl_sync_task_do(spa_get_dsl(spa), spa_change_guid_check,
+           spa_change_guid_sync, spa, &guid, 5);
+
+       if (error == 0) {
+               spa_config_sync(spa, B_FALSE, B_TRUE);
+               spa_event_notify(spa, NULL, FM_EREPORT_ZFS_POOL_REGUID);
+       }
+
+       mutex_exit(&spa_namespace_lock);
+
+       return (error);
+}
+
 /*
  * ==========================================================================
  * SPA state manipulation (open/create/destroy/import/export)
@@ -612,47 +809,146 @@ spa_get_errlists(spa_t *spa, avl_tree_t *last, avl_tree_t *scrub)
            offsetof(spa_error_entry_t, se_avl));
 }
 
-static taskq_t *
-spa_taskq_create(spa_t *spa, const char *name, enum zti_modes mode,
-    uint_t value, uint_t flags)
+static void
+spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
 {
+       const zio_taskq_info_t *ztip = &zio_taskqs[t][q];
+       enum zti_modes mode = ztip->zti_mode;
+       uint_t value = ztip->zti_value;
+       uint_t count = ztip->zti_count;
+       spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
+       char name[32];
+       uint_t i, flags = 0;
        boolean_t batch = B_FALSE;
 
-       switch (mode) {
-       case zti_mode_null:
-               return (NULL);          /* no taskq needed */
+       if (mode == ZTI_MODE_NULL) {
+               tqs->stqs_count = 0;
+               tqs->stqs_taskq = NULL;
+               return;
+       }
 
-       case zti_mode_fixed:
-               ASSERT3U(value, >=, 1);
-               value = MAX(value, 1);
-               break;
+       ASSERT3U(count, >, 0);
 
-       case zti_mode_batch:
-               batch = B_TRUE;
-               flags |= TASKQ_THREADS_CPU_PCT;
-               value = zio_taskq_batch_pct;
-               break;
+       tqs->stqs_count = count;
+       tqs->stqs_taskq = kmem_alloc(count * sizeof (taskq_t *), KM_SLEEP);
 
-       case zti_mode_online_percent:
-               flags |= TASKQ_THREADS_CPU_PCT;
-               break;
+       for (i = 0; i < count; i++) {
+               taskq_t *tq;
 
-       default:
-               panic("unrecognized mode for %s taskq (%u:%u) in "
-                   "spa_activate()",
-                   name, mode, value);
-               break;
+               switch (mode) {
+               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_%s taskq (%u:%u) in "
+                           "spa_activate()",
+                           zio_type_name[t], zio_taskq_types[q], mode, value);
+                       break;
+               }
+
+               if (count > 1) {
+                       (void) snprintf(name, sizeof (name), "%s_%s_%u",
+                           zio_type_name[t], zio_taskq_types[q], i);
+               } else {
+                       (void) snprintf(name, sizeof (name), "%s_%s",
+                           zio_type_name[t], zio_taskq_types[q]);
+               }
+
+               if (zio_taskq_sysdc && spa->spa_proc != &p0) {
+                       if (batch)
+                               flags |= TASKQ_DC_BATCH;
+
+                       tq = taskq_create_sysdc(name, value, 50, INT_MAX,
+                           spa->spa_proc, zio_taskq_basedc, flags);
+               } else {
+                       tq = taskq_create_proc(name, value, maxclsyspri, 50,
+                           INT_MAX, spa->spa_proc, flags);
+               }
+
+               tqs->stqs_taskq[i] = tq;
+       }
+}
+
+static void
+spa_taskqs_fini(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
+{
+       spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
+       uint_t i;
+
+       if (tqs->stqs_taskq == NULL) {
+               ASSERT3U(tqs->stqs_count, ==, 0);
+               return;
+       }
+
+       for (i = 0; i < tqs->stqs_count; i++) {
+               ASSERT3P(tqs->stqs_taskq[i], !=, NULL);
+               taskq_destroy(tqs->stqs_taskq[i]);
        }
 
-       if (zio_taskq_sysdc && spa->spa_proc != &p0) {
-               if (batch)
-                       flags |= TASKQ_DC_BATCH;
+       kmem_free(tqs->stqs_taskq, tqs->stqs_count * sizeof (taskq_t *));
+       tqs->stqs_taskq = NULL;
+}
+
+/*
+ * Dispatch a task to the appropriate taskq for the ZFS I/O type and priority.
+ * Note that a type may have multiple discrete taskqs to avoid lock contention
+ * on the taskq itself. In that case we choose which taskq at random by using
+ * the low bits of gethrtime().
+ */
+void
+spa_taskq_dispatch_ent(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
+    task_func_t *func, void *arg, uint_t flags, taskq_ent_t *ent)
+{
+       spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
+       taskq_t *tq;
+
+       ASSERT3P(tqs->stqs_taskq, !=, NULL);
+       ASSERT3U(tqs->stqs_count, !=, 0);
 
-               return (taskq_create_sysdc(name, value, 50, INT_MAX,
-                   spa->spa_proc, zio_taskq_basedc, flags));
+       if (tqs->stqs_count == 1) {
+               tq = tqs->stqs_taskq[0];
+       } else {
+               tq = tqs->stqs_taskq[((uint64_t)gethrtime()) % tqs->stqs_count];
        }
-       return (taskq_create_proc(name, value, maxclsyspri, 50, INT_MAX,
-           spa->spa_proc, flags));
+
+       taskq_dispatch_ent(tq, func, arg, flags, ent);
+}
+
+/*
+ * Same as spa_taskq_dispatch_ent() but block on the task until completion.
+ */
+void
+spa_taskq_dispatch_sync(spa_t *spa, zio_type_t t, zio_taskq_type_t q,
+    task_func_t *func, void *arg, uint_t flags)
+{
+       spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
+       taskq_t *tq;
+       taskqid_t id;
+
+       ASSERT3P(tqs->stqs_taskq, !=, NULL);
+       ASSERT3U(tqs->stqs_count, !=, 0);
+
+       if (tqs->stqs_count == 1) {
+               tq = tqs->stqs_taskq[0];
+       } else {
+               tq = tqs->stqs_taskq[((uint64_t)gethrtime()) % tqs->stqs_count];
+       }
+
+       id = taskq_dispatch(tq, func, arg, flags);
+       if (id)
+               taskq_wait_id(tq, id);
 }
 
 static void
@@ -662,20 +958,7 @@ spa_create_zio_taskqs(spa_t *spa)
 
        for (t = 0; t < ZIO_TYPES; t++) {
                for (q = 0; q < ZIO_TASKQ_TYPES; q++) {
-                       const zio_taskq_info_t *ztip = &zio_taskqs[t][q];
-                       enum zti_modes mode = ztip->zti_mode;
-                       uint_t value = ztip->zti_value;
-                       uint_t flags = TASKQ_PREPOPULATE;
-                       char name[32];
-
-                       if (t == ZIO_TYPE_WRITE)
-                               flags |= TASKQ_NORECLAIM;
-
-                       (void) snprintf(name, sizeof (name),
-                           "%s_%s", zio_type_name[t], zio_taskq_types[q]);
-
-                       spa->spa_zio_taskq[t][q] =
-                           spa_taskq_create(spa, name, mode, value, flags);
+                       spa_taskqs_init(spa, t, q);
                }
        }
 }
@@ -834,11 +1117,11 @@ spa_deactivate(spa_t *spa)
        list_destroy(&spa->spa_config_dirty_list);
        list_destroy(&spa->spa_state_dirty_list);
 
+       taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+
        for (t = 0; t < ZIO_TYPES; t++) {
                for (q = 0; q < ZIO_TASKQ_TYPES; q++) {
-                       if (spa->spa_zio_taskq[t][q] != NULL)
-                               taskq_destroy(spa->spa_zio_taskq[t][q]);
-                       spa->spa_zio_taskq[t][q] = NULL;
+                       spa_taskqs_fini(spa, t, q);
                }
        }
 
@@ -1004,8 +1287,10 @@ spa_unload(spa_t *spa)
        }
        spa->spa_spares.sav_count = 0;
 
-       for (i = 0; i < spa->spa_l2cache.sav_count; i++)
+       for (i = 0; i < spa->spa_l2cache.sav_count; i++) {
+               vdev_clear_stats(spa->spa_l2cache.sav_vdevs[i]);
                vdev_free(spa->spa_l2cache.sav_vdevs[i]);
+       }
        if (spa->spa_l2cache.sav_vdevs) {
                kmem_free(spa->spa_l2cache.sav_vdevs,
                    spa->spa_l2cache.sav_count * sizeof (void *));
@@ -1019,6 +1304,11 @@ spa_unload(spa_t *spa)
 
        spa->spa_async_suspended = 0;
 
+       if (spa->spa_comment != NULL) {
+               spa_strfree(spa->spa_comment);
+               spa->spa_comment = NULL;
+       }
+
        spa_config_exit(spa, SCL_ALL, FTAG);
 }
 
@@ -1078,7 +1368,7 @@ spa_load_spares(spa_t *spa)
         * active configuration, then we also mark this vdev as an active spare.
         */
        spa->spa_spares.sav_vdevs = kmem_alloc(nspares * sizeof (void *),
-           KM_SLEEP);
+           KM_PUSHPAGE);
        for (i = 0; i < spa->spa_spares.sav_count; i++) {
                VERIFY(spa_config_parse(spa, &vd, spares[i], NULL, 0,
                    VDEV_ALLOC_SPARE) == 0);
@@ -1126,7 +1416,7 @@ spa_load_spares(spa_t *spa)
            DATA_TYPE_NVLIST_ARRAY) == 0);
 
        spares = kmem_alloc(spa->spa_spares.sav_count * sizeof (void *),
-           KM_SLEEP);
+           KM_PUSHPAGE);
        for (i = 0; i < spa->spa_spares.sav_count; i++)
                spares[i] = vdev_config_generate(spa,
                    spa->spa_spares.sav_vdevs[i], B_TRUE, VDEV_CONFIG_SPARE);
@@ -1160,7 +1450,7 @@ spa_load_l2cache(spa_t *spa)
        if (sav->sav_config != NULL) {
                VERIFY(nvlist_lookup_nvlist_array(sav->sav_config,
                    ZPOOL_CONFIG_L2CACHE, &l2cache, &nl2cache) == 0);
-               newvdevs = kmem_alloc(nl2cache * sizeof (void *), KM_SLEEP);
+               newvdevs = kmem_alloc(nl2cache * sizeof (void *), KM_PUSHPAGE);
        } else {
                nl2cache = 0;
        }
@@ -1228,11 +1518,13 @@ spa_load_l2cache(spa_t *spa)
 
                vd = oldvdevs[i];
                if (vd != NULL) {
+                       ASSERT(vd->vdev_isl2cache);
+
                        if (spa_l2cache_exists(vd->vdev_guid, &pool) &&
                            pool != 0ULL && l2arc_vdev_present(vd))
                                l2arc_remove_vdev(vd);
-                       (void) vdev_close(vd);
-                       spa_l2cache_remove(vd);
+                       vdev_clear_stats(vd);
+                       vdev_free(vd);
                }
        }
 
@@ -1252,7 +1544,7 @@ spa_load_l2cache(spa_t *spa)
        VERIFY(nvlist_remove(sav->sav_config, ZPOOL_CONFIG_L2CACHE,
            DATA_TYPE_NVLIST_ARRAY) == 0);
 
-       l2cache = kmem_alloc(sav->sav_count * sizeof (void *), KM_SLEEP);
+       l2cache = kmem_alloc(sav->sav_count * sizeof (void *), KM_PUSHPAGE);
        for (i = 0; i < sav->sav_count; i++)
                l2cache[i] = vdev_config_generate(spa,
                    sav->sav_vdevs[i], B_TRUE, VDEV_CONFIG_L2CACHE);
@@ -1274,11 +1566,14 @@ load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
        int error;
        *value = NULL;
 
-       VERIFY(0 == dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db));
+       error = dmu_bonus_hold(spa->spa_meta_objset, obj, FTAG, &db);
+       if (error)
+               return (error);
+
        nvsize = *(uint64_t *)db->db_data;
        dmu_buf_rele(db, FTAG);
 
-       packed = kmem_alloc(nvsize, KM_SLEEP | KM_NODEBUG);
+       packed = kmem_alloc(nvsize, KM_PUSHPAGE | KM_NODEBUG);
        error = dmu_read(spa->spa_meta_objset, obj, 0, nvsize, packed,
            DMU_READ_PREFETCH);
        if (error == 0)
@@ -1334,8 +1629,8 @@ spa_config_valid(spa_t *spa, nvlist_t *config)
                uint64_t idx = 0;
 
                child = kmem_alloc(rvd->vdev_children * sizeof (nvlist_t **),
-                   KM_SLEEP);
-               VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+                   KM_PUSHPAGE);
+               VERIFY(nvlist_alloc(&nv, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
 
                for (c = 0; c < rvd->vdev_children; c++) {
                        vdev_t *tvd = rvd->vdev_child[c];
@@ -1549,7 +1844,7 @@ spa_load_verify_done(zio_t *zio)
        int error = zio->io_error;
 
        if (error) {
-               if ((BP_GET_LEVEL(bp) != 0 || dmu_ot[type].ot_metadata) &&
+               if ((BP_GET_LEVEL(bp) != 0 || DMU_OT_IS_METADATA(type)) &&
                    type != DMU_OT_INTENT_LOG)
                        atomic_add_64(&sle->sle_meta_count, 1);
                else
@@ -1561,7 +1856,7 @@ spa_load_verify_done(zio_t *zio)
 /*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)
+    const zbookmark_t *zb, const dnode_phys_t *dnp, void *arg)
 {
        if (bp != NULL) {
                zio_t *rio = arg;
@@ -1690,7 +1985,7 @@ spa_try_repair(spa_t *spa, nvlist_t *config)
            &glist, &gcount) != 0)
                return;
 
-       vd = kmem_zalloc(gcount * sizeof (vdev_t *), KM_SLEEP);
+       vd = kmem_zalloc(gcount * sizeof (vdev_t *), KM_PUSHPAGE);
 
        /* attempt to online all the vdevs & validate */
        attempt_reopen = B_TRUE;
@@ -1744,6 +2039,7 @@ spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type,
 {
        nvlist_t *config = spa->spa_config;
        char *ereport = FM_EREPORT_ZFS_POOL;
+       char *comment;
        int error;
        uint64_t pool_guid;
        nvlist_t *nvl;
@@ -1751,6 +2047,10 @@ spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type,
        if (nvlist_lookup_uint64(config, ZPOOL_CONFIG_POOL_GUID, &pool_guid))
                return (EINVAL);
 
+       ASSERT(spa->spa_comment == NULL);
+       if (nvlist_lookup_string(config, ZPOOL_CONFIG_COMMENT, &comment) == 0)
+               spa->spa_comment = spa_strdup(comment);
+
        /*
         * Versioning wasn't explicitly added to the label until later, so if
         * it's not present treat it as the initial version.
@@ -1766,14 +2066,17 @@ spa_load(spa_t *spa, spa_load_state_t state, spa_import_type_t type,
            spa_guid_exists(pool_guid, 0)) {
                error = EEXIST;
        } else {
-               spa->spa_load_guid = pool_guid;
+               spa->spa_config_guid = pool_guid;
 
                if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_SPLIT,
                    &nvl) == 0) {
                        VERIFY(nvlist_dup(nvl, &spa->spa_config_splitting,
-                           KM_SLEEP) == 0);
+                           KM_PUSHPAGE) == 0);
                }
 
+               nvlist_free(spa->spa_load_info);
+               spa->spa_load_info = fnvlist_alloc();
+
                gethrestime(&spa->spa_loaded_ts);
                error = spa_load_impl(spa, pool_guid, config, state, type,
                    mosconfig, &ereport);
@@ -1807,12 +2110,14 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
 {
        int error = 0;
        nvlist_t *nvroot = NULL;
+       nvlist_t *label;
        vdev_t *rvd;
        uberblock_t *ub = &spa->spa_uberblock;
        uint64_t children, config_cache_txg = spa->spa_config_txg;
        int orig_mode = spa->spa_mode;
        int parse;
        uint64_t obj;
+       boolean_t missing_feat_write = B_FALSE;
 
        /*
         * If this is an untrusted config, access the pool in read-only mode.
@@ -1879,7 +2184,7 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
         */
        if (type != SPA_IMPORT_ASSEMBLE) {
                spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
-               error = vdev_validate(rvd);
+               error = vdev_validate(rvd, mosconfig);
                spa_config_exit(spa, SCL_ALL, FTAG);
 
                if (error != 0)
@@ -1892,19 +2197,79 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
        /*
         * Find the best uberblock.
         */
-       vdev_uberblock_load(NULL, rvd, ub);
+       vdev_uberblock_load(rvd, ub, &label);
 
        /*
         * If we weren't able to find a single valid uberblock, return failure.
         */
-       if (ub->ub_txg == 0)
+       if (ub->ub_txg == 0) {
+               nvlist_free(label);
                return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, ENXIO));
+       }
 
        /*
-        * If the pool is newer than the code, we can't open it.
+        * If the pool has an unsupported version we can't open it.
         */
-       if (ub->ub_version > SPA_VERSION)
+       if (!SPA_VERSION_IS_SUPPORTED(ub->ub_version)) {
+               nvlist_free(label);
                return (spa_vdev_err(rvd, VDEV_AUX_VERSION_NEWER, ENOTSUP));
+       }
+
+       if (ub->ub_version >= SPA_VERSION_FEATURES) {
+               nvlist_t *features;
+
+               /*
+                * If we weren't able to find what's necessary for reading the
+                * MOS in the label, return failure.
+                */
+               if (label == NULL || nvlist_lookup_nvlist(label,
+                   ZPOOL_CONFIG_FEATURES_FOR_READ, &features) != 0) {
+                       nvlist_free(label);
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA,
+                           ENXIO));
+               }
+
+               /*
+                * Update our in-core representation with the definitive values
+                * from the label.
+                */
+               nvlist_free(spa->spa_label_features);
+               VERIFY(nvlist_dup(features, &spa->spa_label_features, 0) == 0);
+       }
+
+       nvlist_free(label);
+
+       /*
+        * Look through entries in the label nvlist's features_for_read. If
+        * there is a feature listed there which we don't understand then we
+        * cannot open a pool.
+        */
+       if (ub->ub_version >= SPA_VERSION_FEATURES) {
+               nvlist_t *unsup_feat;
+               nvpair_t *nvp;
+
+               VERIFY(nvlist_alloc(&unsup_feat, NV_UNIQUE_NAME, KM_SLEEP) ==
+                   0);
+
+               for (nvp = nvlist_next_nvpair(spa->spa_label_features, NULL);
+                   nvp != NULL;
+                   nvp = nvlist_next_nvpair(spa->spa_label_features, nvp)) {
+                       if (!zfeature_is_supported(nvpair_name(nvp))) {
+                               VERIFY(nvlist_add_string(unsup_feat,
+                                   nvpair_name(nvp), "") == 0);
+                       }
+               }
+
+               if (!nvlist_empty(unsup_feat)) {
+                       VERIFY(nvlist_add_nvlist(spa->spa_load_info,
+                           ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat) == 0);
+                       nvlist_free(unsup_feat);
+                       return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
+                           ENOTSUP));
+               }
+
+               nvlist_free(unsup_feat);
+       }
 
        /*
         * If the vdev guid sum doesn't match the uberblock, we have an
@@ -1938,7 +2303,7 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
        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);
+       error = dsl_pool_init(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;
@@ -1946,6 +2311,89 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
        if (spa_dir_prop(spa, DMU_POOL_CONFIG, &spa->spa_config_object) != 0)
                return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
 
+       if (spa_version(spa) >= SPA_VERSION_FEATURES) {
+               boolean_t missing_feat_read = B_FALSE;
+               nvlist_t *unsup_feat, *enabled_feat;
+
+               if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_READ,
+                   &spa->spa_feat_for_read_obj) != 0) {
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+               }
+
+               if (spa_dir_prop(spa, DMU_POOL_FEATURES_FOR_WRITE,
+                   &spa->spa_feat_for_write_obj) != 0) {
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+               }
+
+               if (spa_dir_prop(spa, DMU_POOL_FEATURE_DESCRIPTIONS,
+                   &spa->spa_feat_desc_obj) != 0) {
+                       return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+               }
+
+               enabled_feat = fnvlist_alloc();
+               unsup_feat = fnvlist_alloc();
+
+               if (!feature_is_supported(spa->spa_meta_objset,
+                   spa->spa_feat_for_read_obj, spa->spa_feat_desc_obj,
+                   unsup_feat, enabled_feat))
+                       missing_feat_read = B_TRUE;
+
+               if (spa_writeable(spa) || state == SPA_LOAD_TRYIMPORT) {
+                       if (!feature_is_supported(spa->spa_meta_objset,
+                           spa->spa_feat_for_write_obj, spa->spa_feat_desc_obj,
+                           unsup_feat, enabled_feat)) {
+                               missing_feat_write = B_TRUE;
+                       }
+               }
+
+               fnvlist_add_nvlist(spa->spa_load_info,
+                   ZPOOL_CONFIG_ENABLED_FEAT, enabled_feat);
+
+               if (!nvlist_empty(unsup_feat)) {
+                       fnvlist_add_nvlist(spa->spa_load_info,
+                           ZPOOL_CONFIG_UNSUP_FEAT, unsup_feat);
+               }
+
+               fnvlist_free(enabled_feat);
+               fnvlist_free(unsup_feat);
+
+               if (!missing_feat_read) {
+                       fnvlist_add_boolean(spa->spa_load_info,
+                           ZPOOL_CONFIG_CAN_RDONLY);
+               }
+
+               /*
+                * If the state is SPA_LOAD_TRYIMPORT, our objective is
+                * twofold: to determine whether the pool is available for
+                * import in read-write mode and (if it is not) whether the
+                * pool is available for import in read-only mode. If the pool
+                * is available for import in read-write mode, it is displayed
+                * as available in userland; if it is not available for import
+                * in read-only mode, it is displayed as unavailable in
+                * userland. If the pool is available for import in read-only
+                * mode but not read-write mode, it is displayed as unavailable
+                * in userland with a special note that the pool is actually
+                * available for open in read-only mode.
+                *
+                * As a result, if the state is SPA_LOAD_TRYIMPORT and we are
+                * missing a feature for write, we must first determine whether
+                * the pool can be opened read-only before returning to
+                * userland in order to know whether to display the
+                * abovementioned note.
+                */
+               if (missing_feat_read || (missing_feat_write &&
+                   spa_writeable(spa))) {
+                       return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT,
+                           ENOTSUP));
+               }
+       }
+
+       spa->spa_is_initializing = B_TRUE;
+       error = dsl_pool_open(spa->spa_dsl_pool);
+       spa->spa_is_initializing = B_FALSE;
+       if (error != 0)
+               return (spa_vdev_err(rvd, VDEV_AUX_CORRUPT_DATA, EIO));
+
        if (!mosconfig) {
                uint64_t hostid;
                nvlist_t *policy = NULL, *nvconfig;
@@ -1976,7 +2424,7 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
                                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",
+                                   "See: http://zfsonlinux.org/msg/ZFS-8000-EY",
                                    spa_name(spa), hostname,
                                    (unsigned long)hostid);
                                return (EBADF);
@@ -2163,7 +2611,7 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
                nvlist_free(nvconfig);
 
                /*
-                * Now that we've validate the config, check the state of the
+                * Now that we've validated the config, check the state of the
                 * root vdev.  If it can't be opened, it indicates one or
                 * more toplevel vdevs are faulted.
                 */
@@ -2176,6 +2624,17 @@ spa_load_impl(spa_t *spa, uint64_t pool_guid, nvlist_t *config,
                }
        }
 
+       if (missing_feat_write) {
+               ASSERT(state == SPA_LOAD_TRYIMPORT);
+
+               /*
+                * At this point, we know that we can open the pool in
+                * read-only mode but not read-write mode. We now have enough
+                * information and can return to userland.
+                */
+               return (spa_vdev_err(rvd, VDEV_AUX_UNSUP_FEAT, ENOTSUP));
+       }
+
        /*
         * We've successfully opened the pool, verify that we're ready
         * to start pushing transactions.
@@ -2286,10 +2745,18 @@ spa_load_retry(spa_t *spa, spa_load_state_t state, int mosconfig)
        return (spa_load(spa, state, SPA_IMPORT_EXISTING, mosconfig));
 }
 
+/*
+ * If spa_load() fails this function will try loading prior txg's. If
+ * 'state' is SPA_LOAD_RECOVER and one of these loads succeeds the pool
+ * will be rewound to that txg. If 'state' is not SPA_LOAD_RECOVER this
+ * function will not rewind the pool and will return the same error as
+ * spa_load().
+ */
 static int
 spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
     uint64_t max_request, int rewind_flags)
 {
+       nvlist_t *loadinfo = NULL;
        nvlist_t *config = NULL;
        int load_error, rewind_error;
        uint64_t safe_rewind_txg;
@@ -2318,9 +2785,18 @@ spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
                return (load_error);
        }
 
-       /* Price of rolling back is discarding txgs, including log */
-       if (state == SPA_LOAD_RECOVER)
+       if (state == SPA_LOAD_RECOVER) {
+               /* Price of rolling back is discarding txgs, including log */
                spa_set_log_state(spa, SPA_LOG_CLEAR);
+       } else {
+               /*
+                * If we aren't rolling back save the load info from our first
+                * import attempt so that we can restore it after attempting
+                * to rewind.
+                */
+               loadinfo = spa->spa_load_info;
+               spa->spa_load_info = fnvlist_alloc();
+       }
 
        spa->spa_load_max_txg = spa->spa_last_ubsync_txg;
        safe_rewind_txg = spa->spa_last_ubsync_txg - TXG_DEFER_SIZE;
@@ -2344,7 +2820,20 @@ spa_load_best(spa_t *spa, spa_load_state_t state, int mosconfig,
        if (config && (rewind_error || state != SPA_LOAD_RECOVER))
                spa_config_set(spa, config);
 
-       return (state == SPA_LOAD_RECOVER ? rewind_error : load_error);
+       if (state == SPA_LOAD_RECOVER) {
+               ASSERT3P(loadinfo, ==, NULL);
+               return (rewind_error);
+       } else {
+               /* Store the rewind info as part of the initial load info */
+               fnvlist_add_nvlist(loadinfo, ZPOOL_CONFIG_REWIND_INFO,
+                   spa->spa_load_info);
+
+               /* Restore the initial load info */
+               fnvlist_free(spa->spa_load_info);
+               spa->spa_load_info = loadinfo;
+
+               return (load_error);
+       }
 }
 
 /*
@@ -2428,7 +2917,7 @@ spa_open_common(const char *pool, spa_t **spapp, void *tag, nvlist_t *nvpolicy,
                         */
                        if (config != NULL && spa->spa_config) {
                                VERIFY(nvlist_dup(spa->spa_config, config,
-                                   KM_SLEEP) == 0);
+                                   KM_PUSHPAGE) == 0);
                                VERIFY(nvlist_add_nvlist(*config,
                                    ZPOOL_CONFIG_LOAD_INFO,
                                    spa->spa_load_info) == 0);
@@ -2614,8 +3103,50 @@ spa_add_l2cache(spa_t *spa, nvlist_t *config)
        }
 }
 
+static void
+spa_add_feature_stats(spa_t *spa, nvlist_t *config)
+{
+       nvlist_t *features;
+       zap_cursor_t zc;
+       zap_attribute_t za;
+
+       ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));
+       VERIFY(nvlist_alloc(&features, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+
+       if (spa->spa_feat_for_read_obj != 0) {
+               for (zap_cursor_init(&zc, spa->spa_meta_objset,
+                   spa->spa_feat_for_read_obj);
+                   zap_cursor_retrieve(&zc, &za) == 0;
+                   zap_cursor_advance(&zc)) {
+                       ASSERT(za.za_integer_length == sizeof (uint64_t) &&
+                           za.za_num_integers == 1);
+                       VERIFY3U(0, ==, nvlist_add_uint64(features, za.za_name,
+                           za.za_first_integer));
+               }
+               zap_cursor_fini(&zc);
+       }
+
+       if (spa->spa_feat_for_write_obj != 0) {
+               for (zap_cursor_init(&zc, spa->spa_meta_objset,
+                   spa->spa_feat_for_write_obj);
+                   zap_cursor_retrieve(&zc, &za) == 0;
+                   zap_cursor_advance(&zc)) {
+                       ASSERT(za.za_integer_length == sizeof (uint64_t) &&
+                           za.za_num_integers == 1);
+                       VERIFY3U(0, ==, nvlist_add_uint64(features, za.za_name,
+                           za.za_first_integer));
+               }
+               zap_cursor_fini(&zc);
+       }
+
+       VERIFY(nvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
+           features) == 0);
+       nvlist_free(features);
+}
+
 int
-spa_get_stats(const char *name, nvlist_t **config, char *altroot, size_t buflen)
+spa_get_stats(const char *name, nvlist_t **config,
+    char *altroot, size_t buflen)
 {
        int error;
        spa_t *spa;
@@ -2650,6 +3181,7 @@ spa_get_stats(const char *name, nvlist_t **config, char *altroot, size_t buflen)
 
                        spa_add_spares(spa, *config);
                        spa_add_l2cache(spa, *config);
+                       spa_add_feature_stats(spa, *config);
                }
        }
 
@@ -2740,6 +3272,7 @@ spa_validate_aux_devs(spa_t *spa, nvlist_t *nvroot, uint64_t crtxg, int mode,
                if ((strcmp(config, ZPOOL_CONFIG_L2CACHE) == 0) &&
                    strcmp(vd->vdev_ops->vdev_op_type, VDEV_TYPE_DISK) != 0) {
                        error = ENOTBLK;
+                       vdev_free(vd);
                        goto out;
                }
 #endif
@@ -2803,13 +3336,13 @@ spa_set_aux_vdevs(spa_aux_vdev_t *sav, nvlist_t **devs, int ndevs,
                    &olddevs, &oldndevs) == 0);
 
                newdevs = kmem_alloc(sizeof (void *) *
-                   (ndevs + oldndevs), KM_SLEEP);
+                   (ndevs + oldndevs), KM_PUSHPAGE);
                for (i = 0; i < oldndevs; i++)
                        VERIFY(nvlist_dup(olddevs[i], &newdevs[i],
-                           KM_SLEEP) == 0);
+                           KM_PUSHPAGE) == 0);
                for (i = 0; i < ndevs; i++)
                        VERIFY(nvlist_dup(devs[i], &newdevs[i + oldndevs],
-                           KM_SLEEP) == 0);
+                           KM_PUSHPAGE) == 0);
 
                VERIFY(nvlist_remove(sav->sav_config, config,
                    DATA_TYPE_NVLIST_ARRAY) == 0);
@@ -2824,7 +3357,7 @@ spa_set_aux_vdevs(spa_aux_vdev_t *sav, nvlist_t **devs, int ndevs,
                 * Generate a new dev list.
                 */
                VERIFY(nvlist_alloc(&sav->sav_config, NV_UNIQUE_NAME,
-                   KM_SLEEP) == 0);
+                   KM_PUSHPAGE) == 0);
                VERIFY(nvlist_add_nvlist_array(sav->sav_config, config,
                    devs, ndevs) == 0);
        }
@@ -2849,10 +3382,6 @@ spa_l2cache_drop(spa_t *spa)
                if (spa_l2cache_exists(vd->vdev_guid, &pool) &&
                    pool != 0ULL && l2arc_vdev_present(vd))
                        l2arc_remove_vdev(vd);
-               if (vd->vdev_isl2cache)
-                       spa_l2cache_remove(vd);
-               vdev_clear_stats(vd);
-               (void) vdev_close(vd);
        }
 }
 
@@ -2873,6 +3402,8 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        nvlist_t **spares, **l2cache;
        uint_t nspares, nl2cache;
        uint64_t version, obj;
+       boolean_t has_features;
+       nvpair_t *elem;
        int c;
 
        /*
@@ -2899,10 +3430,18 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
                return (error);
        }
 
-       if (nvlist_lookup_uint64(props, zpool_prop_to_name(ZPOOL_PROP_VERSION),
-           &version) != 0)
+       has_features = B_FALSE;
+       for (elem = nvlist_next_nvpair(props, NULL);
+           elem != NULL; elem = nvlist_next_nvpair(props, elem)) {
+               if (zpool_prop_feature(nvpair_name(elem)))
+                       has_features = B_TRUE;
+       }
+
+       if (has_features || nvlist_lookup_uint64(props,
+           zpool_prop_to_name(ZPOOL_PROP_VERSION), &version) != 0) {
                version = SPA_VERSION;
-       ASSERT(version <= SPA_VERSION);
+       }
+       ASSERT(SPA_VERSION_IS_SUPPORTED(version));
 
        spa->spa_first_txg = txg;
        spa->spa_uberblock.ub_txg = txg - 1;
@@ -2954,7 +3493,7 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_SPARES,
            &spares, &nspares) == 0) {
                VERIFY(nvlist_alloc(&spa->spa_spares.sav_config, NV_UNIQUE_NAME,
-                   KM_SLEEP) == 0);
+                   KM_PUSHPAGE) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
                    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
@@ -2969,7 +3508,7 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
        if (nvlist_lookup_nvlist_array(nvroot, ZPOOL_CONFIG_L2CACHE,
            &l2cache, &nl2cache) == 0) {
                VERIFY(nvlist_alloc(&spa->spa_l2cache.sav_config,
-                   NV_UNIQUE_NAME, KM_SLEEP) == 0);
+                   NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_l2cache.sav_config,
                    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache) == 0);
                spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
@@ -2978,8 +3517,10 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
                spa->spa_l2cache.sav_sync = B_TRUE;
        }
 
+       spa->spa_is_initializing = B_TRUE;
        spa->spa_dsl_pool = dp = dsl_pool_create(spa, zplprops, txg);
        spa->spa_meta_objset = dp->dp_meta_objset;
+       spa->spa_is_initializing = B_FALSE;
 
        /*
         * Create DDTs (dedup tables).
@@ -3003,6 +3544,9 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
                cmn_err(CE_PANIC, "failed to add pool config");
        }
 
+       if (spa_version(spa) >= SPA_VERSION_FEATURES)
+               spa_feature_create_zap_objects(spa, tx);
+
        if (zap_add(spa->spa_meta_objset,
            DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_CREATION_VERSION,
            sizeof (uint64_t), 1, &version, tx) != 0) {
@@ -3107,7 +3651,7 @@ spa_generate_rootconf(char *devpath, char *devid, uint64_t *guid)
        /*
         * Put this pool's top-level vdevs into a root vdev.
         */
-       VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+       VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
        VERIFY(nvlist_add_string(nvroot, ZPOOL_CONFIG_TYPE,
            VDEV_TYPE_ROOT) == 0);
        VERIFY(nvlist_add_uint64(nvroot, ZPOOL_CONFIG_ID, 0ULL) == 0);
@@ -3195,7 +3739,7 @@ spa_import_rootpool(char *devpath, char *devid)
        }
 #endif
        if (config == NULL) {
-               cmn_err(CE_NOTE, "Can not read the pool label from '%s'",
+               cmn_err(CE_NOTE, "Cannot read the pool label from '%s'",
                    devpath);
                return (EIO);
        }
@@ -3418,7 +3962,7 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props, uint64_t flags)
                            ZPOOL_CONFIG_SPARES, DATA_TYPE_NVLIST_ARRAY) == 0);
                else
                        VERIFY(nvlist_alloc(&spa->spa_spares.sav_config,
-                           NV_UNIQUE_NAME, KM_SLEEP) == 0);
+                           NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_spares.sav_config,
                    ZPOOL_CONFIG_SPARES, spares, nspares) == 0);
                spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
@@ -3433,7 +3977,7 @@ spa_import(const char *pool, nvlist_t *config, nvlist_t *props, uint64_t flags)
                            ZPOOL_CONFIG_L2CACHE, DATA_TYPE_NVLIST_ARRAY) == 0);
                else
                        VERIFY(nvlist_alloc(&spa->spa_l2cache.sav_config,
-                           NV_UNIQUE_NAME, KM_SLEEP) == 0);
+                           NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
                VERIFY(nvlist_add_nvlist_array(spa->spa_l2cache.sav_config,
                    ZPOOL_CONFIG_L2CACHE, l2cache, nl2cache) == 0);
                spa_config_enter(spa, SCL_ALL, FTAG, RW_WRITER);
@@ -3509,6 +4053,8 @@ spa_tryimport(nvlist_t *tryconfig)
                    state) == 0);
                VERIFY(nvlist_add_uint64(config, ZPOOL_CONFIG_TIMESTAMP,
                    spa->spa_uberblock.ub_timestamp) == 0);
+               VERIFY(nvlist_add_nvlist(config, ZPOOL_CONFIG_LOAD_INFO,
+                   spa->spa_load_info) == 0);
 
                /*
                 * If the bootfs property exists on this pool then we
@@ -3516,7 +4062,7 @@ spa_tryimport(nvlist_t *tryconfig)
                 * pools are bootable.
                 */
                if ((!error || error == EEXIST) && spa->spa_bootfs) {
-                       char *tmpname = kmem_alloc(MAXPATHLEN, KM_SLEEP);
+                       char *tmpname = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
 
                        /*
                         * We have to play games with the name since the
@@ -3525,7 +4071,7 @@ spa_tryimport(nvlist_t *tryconfig)
                        if (dsl_dsobj_to_dsname(spa_name(spa),
                            spa->spa_bootfs, tmpname) == 0) {
                                char *cp;
-                               char *dsname = kmem_alloc(MAXPATHLEN, KM_SLEEP);
+                               char *dsname = kmem_alloc(MAXPATHLEN, KM_PUSHPAGE);
 
                                cp = strchr(tmpname, '/');
                                if (cp == NULL) {
@@ -3848,7 +4394,7 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
        pvd = oldvd->vdev_parent;
 
        if ((error = spa_config_parse(spa, &newrootvd, nvroot, NULL, 0,
-           VDEV_ALLOC_ADD)) != 0)
+           VDEV_ALLOC_ATTACH)) != 0)
                return (spa_vdev_exit(spa, NULL, txg, EINVAL));
 
        if (newrootvd->vdev_children != 1)
@@ -3930,7 +4476,7 @@ spa_vdev_attach(spa_t *spa, uint64_t guid, nvlist_t *nvroot, int replacing)
        if (strcmp(oldvd->vdev_path, newvd->vdev_path) == 0) {
                spa_strfree(oldvd->vdev_path);
                oldvd->vdev_path = kmem_alloc(strlen(newvd->vdev_path) + 5,
-                   KM_SLEEP);
+                   KM_PUSHPAGE);
                (void) sprintf(oldvd->vdev_path, "%s/%s",
                    newvd->vdev_path, "old");
                if (oldvd->vdev_devid != NULL) {
@@ -4325,8 +4871,8 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
            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);
+       vml = kmem_zalloc(children * sizeof (vdev_t *), KM_PUSHPAGE);
+       glist = kmem_zalloc(children * sizeof (uint64_t), KM_PUSHPAGE);
 
        /* then, loop over each vdev and validate it */
        for (c = 0; c < children; c++) {
@@ -4406,7 +4952,7 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
         * Temporarily record the splitting vdevs in the spa config.  This
         * will disappear once the config is regenerated.
         */
-       VERIFY(nvlist_alloc(&nvl, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+       VERIFY(nvlist_alloc(&nvl, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
        VERIFY(nvlist_add_uint64_array(nvl, ZPOOL_CONFIG_SPLIT_LIST,
            glist, children) == 0);
        kmem_free(glist, children * sizeof (uint64_t));
@@ -4453,7 +4999,7 @@ spa_vdev_split_mirror(spa_t *spa, char *newname, nvlist_t *config,
        /* 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);
+                   NV_UNIQUE_NAME, KM_PUSHPAGE) == 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,
@@ -4565,12 +5111,12 @@ spa_vdev_remove_aux(nvlist_t *config, char *name, nvlist_t **dev, int count,
        int i, j;
 
        if (count > 1)
-               newdev = kmem_alloc((count - 1) * sizeof (void *), KM_SLEEP);
+               newdev = kmem_alloc((count - 1) * sizeof (void *), KM_PUSHPAGE);
 
        for (i = 0, j = 0; i < count; i++) {
                if (dev[i] == dev_to_remove)
                        continue;
-               VERIFY(nvlist_dup(dev[i], &newdev[j++], KM_SLEEP) == 0);
+               VERIFY(nvlist_dup(dev[i], &newdev[j++], KM_PUSHPAGE) == 0);
        }
 
        VERIFY(nvlist_remove(config, name, DATA_TYPE_NVLIST_ARRAY) == 0);
@@ -4616,7 +5162,7 @@ spa_vdev_remove_evacuate(spa_t *spa, vdev_t *vd)
         * 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);
+       ASSERT0(vd->vdev_stat.vs_alloc);
        txg = spa_vdev_config_enter(spa);
        vd->vdev_removing = B_TRUE;
        vdev_dirty(vd, 0, NULL, txg);
@@ -5224,11 +5770,11 @@ spa_sync_nvlist(spa_t *spa, uint64_t obj, nvlist_t *nv, dmu_tx_t *tx)
         * information.  This avoids the dbuf_will_dirty() path and
         * saves us a pre-read to get data we don't actually care about.
         */
-       bufsize = P2ROUNDUP(nvsize, SPA_CONFIG_BLOCKSIZE);
-       packed = vmem_alloc(bufsize, KM_SLEEP);
+       bufsize = P2ROUNDUP((uint64_t)nvsize, SPA_CONFIG_BLOCKSIZE);
+       packed = vmem_alloc(bufsize, KM_PUSHPAGE);
 
        VERIFY(nvlist_pack(nv, &packed, &nvsize, NV_ENCODE_XDR,
-           KM_SLEEP) == 0);
+           KM_PUSHPAGE) == 0);
        bzero(packed + nvsize, bufsize - nvsize);
 
        dmu_write(spa->spa_meta_objset, obj, 0, bufsize, packed, tx);
@@ -5266,11 +5812,11 @@ spa_sync_aux_dev(spa_t *spa, spa_aux_vdev_t *sav, dmu_tx_t *tx,
                    &sav->sav_object, tx) == 0);
        }
 
-       VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_SLEEP) == 0);
+       VERIFY(nvlist_alloc(&nvroot, NV_UNIQUE_NAME, KM_PUSHPAGE) == 0);
        if (sav->sav_count == 0) {
                VERIFY(nvlist_add_nvlist_array(nvroot, config, NULL, 0) == 0);
        } else {
-               list = kmem_alloc(sav->sav_count * sizeof (void *), KM_SLEEP);
+               list = kmem_alloc(sav->sav_count * sizeof (void *), KM_PUSHPAGE);
                for (i = 0; i < sav->sav_count; i++)
                        list[i] = vdev_config_generate(spa, sav->sav_vdevs[i],
                            B_FALSE, VDEV_CONFIG_L2CACHE);
@@ -5300,6 +5846,14 @@ spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
        config = spa_config_generate(spa, spa->spa_root_vdev,
            dmu_tx_get_txg(tx), B_FALSE);
 
+       /*
+        * If we're upgrading the spa version then make sure that
+        * the config object gets updated with the correct version.
+        */
+       if (spa->spa_ubsync.ub_version < spa->spa_uberblock.ub_version)
+               fnvlist_add_uint64(config, ZPOOL_CONFIG_VERSION,
+                   spa->spa_uberblock.ub_version);
+
        spa_config_exit(spa, SCL_STATE, FTAG);
 
        if (spa->spa_config_syncing)
@@ -5309,6 +5863,24 @@ spa_sync_config_object(spa_t *spa, dmu_tx_t *tx)
        spa_sync_nvlist(spa, spa->spa_config_object, config, tx);
 }
 
+static void
+spa_sync_version(void *arg1, void *arg2, dmu_tx_t *tx)
+{
+       spa_t *spa = arg1;
+       uint64_t version = *(uint64_t *)arg2;
+
+       /*
+        * Setting the version is special cased when first creating the pool.
+        */
+       ASSERT(tx->tx_txg != TXG_INITIAL);
+
+       ASSERT(SPA_VERSION_IS_SUPPORTED(version));
+       ASSERT(version >= spa_version(spa));
+
+       spa->spa_uberblock.ub_version = version;
+       vdev_config_dirty(spa->spa_root_vdev);
+}
+
 /*
  * Set zpool properties.
  */
@@ -5318,32 +5890,39 @@ spa_sync_props(void *arg1, void *arg2, dmu_tx_t *tx)
        spa_t *spa = arg1;
        objset_t *mos = spa->spa_meta_objset;
        nvlist_t *nvp = arg2;
-       nvpair_t *elem;
-       uint64_t intval;
-       char *strval;
-       zpool_prop_t prop;
-       const char *propname;
-       zprop_type_t proptype;
+       nvpair_t *elem = NULL;
 
        mutex_enter(&spa->spa_props_lock);
 
-       elem = NULL;
        while ((elem = nvlist_next_nvpair(nvp, elem))) {
-               switch (prop = zpool_name_to_prop(nvpair_name(elem))) {
+               uint64_t intval;
+               char *strval, *fname;
+               zpool_prop_t prop;
+               const char *propname;
+               zprop_type_t proptype;
+               zfeature_info_t *feature;
+
+               prop = zpool_name_to_prop(nvpair_name(elem));
+               switch ((int)prop) {
+               case ZPROP_INVAL:
+                       /*
+                        * We checked this earlier in spa_prop_validate().
+                        */
+                       ASSERT(zpool_prop_feature(nvpair_name(elem)));
+
+                       fname = strchr(nvpair_name(elem), '@') + 1;
+                       VERIFY3U(0, ==, zfeature_lookup_name(fname, &feature));
+
+                       spa_feature_enable(spa, feature, tx);
+                       break;
+
                case ZPOOL_PROP_VERSION:
+                       VERIFY(nvpair_value_uint64(elem, &intval) == 0);
                        /*
-                        * Only set version for non-zpool-creation cases
-                        * (set/import). spa_create() needs special care
-                        * for version setting.
+                        * The version is synced seperatly before other
+                        * properties and should be correct by now.
                         */
-                       if (tx->tx_txg != TXG_INITIAL) {
-                               VERIFY(nvpair_value_uint64(elem,
-                                   &intval) == 0);
-                               ASSERT(intval <= SPA_VERSION);
-                               ASSERT(intval >= spa_version(spa));
-                               spa->spa_uberblock.ub_version = intval;
-                               vdev_config_dirty(spa->spa_root_vdev);
-                       }
+                       ASSERT3U(spa_version(spa), >=, intval);
                        break;
 
                case ZPOOL_PROP_ALTROOT:
@@ -5361,19 +5940,29 @@ spa_sync_props(void *arg1, void *arg2, dmu_tx_t *tx)
                         * properties.
                         */
                        break;
+               case ZPOOL_PROP_COMMENT:
+                       VERIFY(nvpair_value_string(elem, &strval) == 0);
+                       if (spa->spa_comment != NULL)
+                               spa_strfree(spa->spa_comment);
+                       spa->spa_comment = spa_strdup(strval);
+                       /*
+                        * We need to dirty the configuration on all the vdevs
+                        * so that their labels get updated.  It's unnecessary
+                        * to do this for pool creation since the vdev's
+                        * configuratoin has already been dirtied.
+                        */
+                       if (tx->tx_txg != TXG_INITIAL)
+                               vdev_config_dirty(spa->spa_root_vdev);
+                       break;
                default:
                        /*
                         * Set pool property values in the poolprops mos object.
                         */
                        if (spa->spa_pool_props_object == 0) {
-                               VERIFY((spa->spa_pool_props_object =
-                                   zap_create(mos, DMU_OT_POOL_PROPS,
-                                   DMU_OT_NONE, 0, tx)) > 0);
-
-                               VERIFY(zap_update(mos,
+                               spa->spa_pool_props_object =
+                                   zap_create_link(mos, DMU_OT_POOL_PROPS,
                                    DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_PROPS,
-                                   8, 1, &spa->spa_pool_props_object, tx)
-                                   == 0);
+                                   tx);
                        }
 
                        /* normalize the property name */
@@ -5472,6 +6061,11 @@ spa_sync_upgrades(spa_t *spa, dmu_tx_t *tx)
                /* Keeping the freedir open increases spa_minref */
                spa->spa_minref += 3;
        }
+
+       if (spa->spa_ubsync.ub_version < SPA_VERSION_FEATURES &&
+           spa->spa_uberblock.ub_version >= SPA_VERSION_FEATURES) {
+               spa_feature_create_zap_objects(spa, tx);
+       }
 }
 
 /*
@@ -5527,6 +6121,12 @@ spa_sync(spa_t *spa, uint64_t txg)
 
        tx = dmu_tx_create_assigned(dp, txg);
 
+       spa->spa_sync_starttime = gethrtime();
+       taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+       spa->spa_deadman_tqid = taskq_dispatch_delay(system_taskq,
+           spa_deadman, spa, TQ_SLEEP, ddi_get_lbolt() +
+           NSEC_TO_TICK(spa->spa_deadman_synctime));
+
        /*
         * If we are upgrading to SPA_VERSION_RAIDZ_DEFLATE this txg,
         * set spa_deflate if we have no raid-z vdevs.
@@ -5563,7 +6163,7 @@ spa_sync(spa_t *spa, uint64_t txg)
                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);
+               VERIFY0(zio_wait(zio));
        }
 
        /*
@@ -5580,7 +6180,7 @@ spa_sync(spa_t *spa, uint64_t txg)
                spa_errlog_sync(spa, txg);
                dsl_pool_sync(dp, txg);
 
-               if (pass <= SYNC_PASS_DEFERRED_FREE) {
+               if (pass < zfs_sync_pass_deferred_free) {
                        zio_t *zio = zio_root(spa, NULL, NULL, 0);
                        bplist_iterate(free_bpl, spa_free_sync_cb,
                            zio, tx);
@@ -5643,6 +6243,9 @@ spa_sync(spa_t *spa, uint64_t txg)
                                    rvd->vdev_children, txg, B_TRUE);
                }
 
+               if (error == 0)
+                       spa->spa_last_synced_guid = rvd->vdev_guid;
+
                spa_config_exit(spa, SCL_STATE, FTAG);
 
                if (error == 0)
@@ -5652,6 +6255,9 @@ spa_sync(spa_t *spa, uint64_t txg)
        }
        dmu_tx_commit(tx);
 
+       taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+       spa->spa_deadman_tqid = 0;
+
        /*
         * Clear the dirty config list.
         */
@@ -5801,7 +6407,7 @@ spa_upgrade(spa_t *spa, uint64_t version)
         * future version would result in an unopenable pool, this shouldn't be
         * possible.
         */
-       ASSERT(spa->spa_uberblock.ub_version <= SPA_VERSION);
+       ASSERT(SPA_VERSION_IS_SUPPORTED(spa->spa_uberblock.ub_version));
        ASSERT(version >= spa->spa_uberblock.ub_version);
 
        spa->spa_uberblock.ub_version = version;