]> git.proxmox.com Git - mirror_zfs.git/blobdiff - module/zfs/vdev.c
vs_alloc can underflow in L2ARC vdevs
[mirror_zfs.git] / module / zfs / vdev.c
index e741a699870a1211202bf60a8dd4ef1234c0dc06..def98ad136f10a2e4c6949db85ae056c4036f2ed 100644 (file)
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
- * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright 2017 Nexenta Systems, Inc.
+ * Copyright (c) 2014 Integros [integros.com]
+ * Copyright 2016 Toomas Soome <tsoome@me.com>
+ * Copyright 2017 Joyent, Inc.
+ * Copyright (c) 2017, Intel Corporation.
  */
 
 #include <sys/zfs_context.h>
 #include <sys/fm/fs/zfs.h>
 #include <sys/spa.h>
 #include <sys/spa_impl.h>
+#include <sys/bpobj.h>
 #include <sys/dmu.h>
 #include <sys/dmu_tx.h>
+#include <sys/dsl_dir.h>
 #include <sys/vdev_impl.h>
 #include <sys/uberblock_impl.h>
 #include <sys/metaslab.h>
 #include <sys/zil.h>
 #include <sys/dsl_scan.h>
 #include <sys/abd.h>
+#include <sys/vdev_initialize.h>
 #include <sys/zvol.h>
 #include <sys/zfs_ratelimit.h>
 
+/* default target for number of metaslabs per top-level vdev */
+int zfs_vdev_default_ms_count = 200;
+
+/* minimum number of metaslabs per top-level vdev */
+int zfs_vdev_min_ms_count = 16;
+
+/* practical upper limit of total metaslabs per top-level vdev */
+int zfs_vdev_ms_count_limit = 1ULL << 17;
+
+/* lower limit for metaslab size (512M) */
+int zfs_vdev_default_ms_shift = 29;
+
+/* upper limit for metaslab size (16G) */
+int zfs_vdev_max_ms_shift = 34;
+
+int vdev_validate_skip = B_FALSE;
+
+/*
+ * Since the DTL space map of a vdev is not expected to have a lot of
+ * entries, we default its block size to 4K.
+ */
+int vdev_dtl_sm_blksz = (1 << 12);
+
+/*
+ * Rate limit slow IO (delay) events to this many per second.
+ */
+unsigned int zfs_slow_io_events_per_second = 20;
+
+/*
+ * Rate limit checksum events after this many checksum errors per second.
+ */
+unsigned int zfs_checksum_events_per_second = 20;
+
+/*
+ * Ignore errors during scrub/resilver.  Allows to work around resilver
+ * upon import when there are pool errors.
+ */
+int zfs_scan_ignore_errors = 0;
+
+/*
+ * vdev-wide space maps that have lots of entries written to them at
+ * the end of each transaction can benefit from a higher I/O bandwidth
+ * (e.g. vdev_obsolete_sm), thus we default their block size to 128K.
+ */
+int vdev_standard_sm_blksz = (1 << 17);
+
 /*
- * When a vdev is added, it will be divided into approximately (but no
- * more than) this number of metaslabs.
+ * Tunable parameter for debugging or performance analysis. Setting this
+ * will cause pool corruption on power loss if a volatile out-of-order
+ * write cache is enabled.
  */
-int metaslabs_per_vdev = 200;
+int zfs_nocacheflush = 0;
+
+/*PRINTFLIKE2*/
+void
+vdev_dbgmsg(vdev_t *vd, const char *fmt, ...)
+{
+       va_list adx;
+       char buf[256];
+
+       va_start(adx, fmt);
+       (void) vsnprintf(buf, sizeof (buf), fmt, adx);
+       va_end(adx);
+
+       if (vd->vdev_path != NULL) {
+               zfs_dbgmsg("%s vdev '%s': %s", vd->vdev_ops->vdev_op_type,
+                   vd->vdev_path, buf);
+       } else {
+               zfs_dbgmsg("%s-%llu vdev (guid %llu): %s",
+                   vd->vdev_ops->vdev_op_type,
+                   (u_longlong_t)vd->vdev_id,
+                   (u_longlong_t)vd->vdev_guid, buf);
+       }
+}
+
+void
+vdev_dbgmsg_print_tree(vdev_t *vd, int indent)
+{
+       char state[20];
+
+       if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops) {
+               zfs_dbgmsg("%*svdev %u: %s", indent, "", vd->vdev_id,
+                   vd->vdev_ops->vdev_op_type);
+               return;
+       }
+
+       switch (vd->vdev_state) {
+       case VDEV_STATE_UNKNOWN:
+               (void) snprintf(state, sizeof (state), "unknown");
+               break;
+       case VDEV_STATE_CLOSED:
+               (void) snprintf(state, sizeof (state), "closed");
+               break;
+       case VDEV_STATE_OFFLINE:
+               (void) snprintf(state, sizeof (state), "offline");
+               break;
+       case VDEV_STATE_REMOVED:
+               (void) snprintf(state, sizeof (state), "removed");
+               break;
+       case VDEV_STATE_CANT_OPEN:
+               (void) snprintf(state, sizeof (state), "can't open");
+               break;
+       case VDEV_STATE_FAULTED:
+               (void) snprintf(state, sizeof (state), "faulted");
+               break;
+       case VDEV_STATE_DEGRADED:
+               (void) snprintf(state, sizeof (state), "degraded");
+               break;
+       case VDEV_STATE_HEALTHY:
+               (void) snprintf(state, sizeof (state), "healthy");
+               break;
+       default:
+               (void) snprintf(state, sizeof (state), "<state %u>",
+                   (uint_t)vd->vdev_state);
+       }
+
+       zfs_dbgmsg("%*svdev %u: %s%s, guid: %llu, path: %s, %s", indent,
+           "", (int)vd->vdev_id, vd->vdev_ops->vdev_op_type,
+           vd->vdev_islog ? " (log)" : "",
+           (u_longlong_t)vd->vdev_guid,
+           vd->vdev_path ? vd->vdev_path : "N/A", state);
+
+       for (uint64_t i = 0; i < vd->vdev_children; i++)
+               vdev_dbgmsg_print_tree(vd->vdev_child[i], indent + 2);
+}
 
 /*
  * Virtual device management.
@@ -67,6 +194,7 @@ static vdev_ops_t *vdev_ops_table[] = {
        &vdev_file_ops,
        &vdev_missing_ops,
        &vdev_hole_ops,
+       &vdev_indirect_ops,
        NULL
 };
 
@@ -85,6 +213,33 @@ vdev_getops(const char *type)
        return (ops);
 }
 
+/* ARGSUSED */
+void
+vdev_default_xlate(vdev_t *vd, const range_seg_t *in, range_seg_t *res)
+{
+       res->rs_start = in->rs_start;
+       res->rs_end = in->rs_end;
+}
+
+/*
+ * Derive the enumerated alloction bias from string input.
+ * String origin is either the per-vdev zap or zpool(1M).
+ */
+static vdev_alloc_bias_t
+vdev_derive_alloc_bias(const char *bias)
+{
+       vdev_alloc_bias_t alloc_bias = VDEV_BIAS_NONE;
+
+       if (strcmp(bias, VDEV_ALLOC_BIAS_LOG) == 0)
+               alloc_bias = VDEV_BIAS_LOG;
+       else if (strcmp(bias, VDEV_ALLOC_BIAS_SPECIAL) == 0)
+               alloc_bias = VDEV_BIAS_SPECIAL;
+       else if (strcmp(bias, VDEV_ALLOC_BIAS_DEDUP) == 0)
+               alloc_bias = VDEV_BIAS_DEDUP;
+
+       return (alloc_bias);
+}
+
 /*
  * Default asize function: return the MAX of psize with the asize of
  * all children.  This is what's used by anything other than RAID-Z.
@@ -94,9 +249,8 @@ vdev_default_asize(vdev_t *vd, uint64_t psize)
 {
        uint64_t asize = P2ROUNDUP(psize, 1ULL << vd->vdev_top->vdev_ashift);
        uint64_t csize;
-       int c;
 
-       for (c = 0; c < vd->vdev_children; c++) {
+       for (int c = 0; c < vd->vdev_children; c++) {
                csize = vdev_psize_to_asize(vd->vdev_child[c], psize);
                asize = MAX(asize, csize);
        }
@@ -134,7 +288,8 @@ vdev_get_min_asize(vdev_t *vd)
         * so each child must provide at least 1/Nth of its asize.
         */
        if (pvd->vdev_ops == &vdev_raidz_ops)
-               return (pvd->vdev_min_asize / pvd->vdev_children);
+               return ((pvd->vdev_min_asize + pvd->vdev_children - 1) /
+                   pvd->vdev_children);
 
        return (pvd->vdev_min_asize);
 }
@@ -142,10 +297,9 @@ vdev_get_min_asize(vdev_t *vd)
 void
 vdev_set_min_asize(vdev_t *vd)
 {
-       int c;
        vd->vdev_min_asize = vdev_get_min_asize(vd);
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_set_min_asize(vd->vdev_child[c]);
 }
 
@@ -168,12 +322,11 @@ vdev_t *
 vdev_lookup_by_guid(vdev_t *vd, uint64_t guid)
 {
        vdev_t *mvd;
-       int c;
 
        if (vd->vdev_guid == guid)
                return (vd);
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                if ((mvd = vdev_lookup_by_guid(vd->vdev_child[c], guid)) !=
                    NULL)
                        return (mvd);
@@ -185,12 +338,11 @@ static int
 vdev_count_leaves_impl(vdev_t *vd)
 {
        int n = 0;
-       int c;
 
        if (vd->vdev_ops->vdev_op_leaf)
                return (1);
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                n += vdev_count_leaves_impl(vd->vdev_child[c]);
 
        return (n);
@@ -199,7 +351,13 @@ vdev_count_leaves_impl(vdev_t *vd)
 int
 vdev_count_leaves(spa_t *spa)
 {
-       return (vdev_count_leaves_impl(spa->spa_root_vdev));
+       int rc;
+
+       spa_config_enter(spa, SCL_VDEV, FTAG, RW_READER);
+       rc = vdev_count_leaves_impl(spa->spa_root_vdev);
+       spa_config_exit(spa, SCL_VDEV, FTAG);
+
+       return (rc);
 }
 
 void
@@ -285,21 +443,27 @@ vdev_compact_children(vdev_t *pvd)
        vdev_t **newchild, *cvd;
        int oldc = pvd->vdev_children;
        int newc;
-       int c;
 
        ASSERT(spa_config_held(pvd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
 
-       for (c = newc = 0; c < oldc; c++)
+       if (oldc == 0)
+               return;
+
+       for (int c = newc = 0; c < oldc; c++)
                if (pvd->vdev_child[c])
                        newc++;
 
-       newchild = kmem_zalloc(newc * sizeof (vdev_t *), KM_SLEEP);
+       if (newc > 0) {
+               newchild = kmem_zalloc(newc * sizeof (vdev_t *), KM_SLEEP);
 
-       for (c = newc = 0; c < oldc; c++) {
-               if ((cvd = pvd->vdev_child[c]) != NULL) {
-                       newchild[newc] = cvd;
-                       cvd->vdev_id = newc++;
+               for (int c = newc = 0; c < oldc; c++) {
+                       if ((cvd = pvd->vdev_child[c]) != NULL) {
+                               newchild[newc] = cvd;
+                               cvd->vdev_id = newc++;
+                       }
                }
+       } else {
+               newchild = NULL;
        }
 
        kmem_free(pvd->vdev_child, oldc * sizeof (vdev_t *));
@@ -314,9 +478,10 @@ vdev_t *
 vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
 {
        vdev_t *vd;
-       int t;
+       vdev_indirect_config_t *vic;
 
        vd = kmem_zalloc(sizeof (vdev_t), KM_SLEEP);
+       vic = &vd->vdev_indirect_config;
 
        if (spa->spa_root_vdev == NULL) {
                ASSERT(ops == &vdev_root_ops);
@@ -347,29 +512,40 @@ vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
        vd->vdev_ops = ops;
        vd->vdev_state = VDEV_STATE_CLOSED;
        vd->vdev_ishole = (ops == &vdev_hole_ops);
+       vic->vic_prev_indirect_vdev = UINT64_MAX;
+
+       rw_init(&vd->vdev_indirect_rwlock, NULL, RW_DEFAULT, NULL);
+       mutex_init(&vd->vdev_obsolete_lock, NULL, MUTEX_DEFAULT, NULL);
+       vd->vdev_obsolete_segments = range_tree_create(NULL, NULL);
 
        /*
         * Initialize rate limit structs for events.  We rate limit ZIO delay
         * and checksum events so that we don't overwhelm ZED with thousands
         * of events when a disk is acting up.
         */
-       zfs_ratelimit_init(&vd->vdev_delay_rl, DELAYS_PER_SECOND, 1);
-       zfs_ratelimit_init(&vd->vdev_checksum_rl, CHECKSUMS_PER_SECOND, 1);
+       zfs_ratelimit_init(&vd->vdev_delay_rl, &zfs_slow_io_events_per_second,
+           1);
+       zfs_ratelimit_init(&vd->vdev_checksum_rl,
+           &zfs_checksum_events_per_second, 1);
 
        list_link_init(&vd->vdev_config_dirty_node);
        list_link_init(&vd->vdev_state_dirty_node);
+       list_link_init(&vd->vdev_initialize_node);
        mutex_init(&vd->vdev_dtl_lock, NULL, MUTEX_NOLOCKDEP, NULL);
        mutex_init(&vd->vdev_stat_lock, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&vd->vdev_probe_lock, NULL, MUTEX_DEFAULT, NULL);
-       mutex_init(&vd->vdev_queue_lock, NULL, MUTEX_DEFAULT, NULL);
-
-       for (t = 0; t < DTL_TYPES; t++) {
-               vd->vdev_dtl[t] = range_tree_create(NULL, NULL,
-                   &vd->vdev_dtl_lock);
+       mutex_init(&vd->vdev_scan_io_queue_lock, NULL, MUTEX_DEFAULT, NULL);
+       mutex_init(&vd->vdev_initialize_lock, NULL, MUTEX_DEFAULT, NULL);
+       mutex_init(&vd->vdev_initialize_io_lock, NULL, MUTEX_DEFAULT, NULL);
+       cv_init(&vd->vdev_initialize_cv, NULL, CV_DEFAULT, NULL);
+       cv_init(&vd->vdev_initialize_io_cv, NULL, CV_DEFAULT, NULL);
+
+       for (int t = 0; t < DTL_TYPES; t++) {
+               vd->vdev_dtl[t] = range_tree_create(NULL, NULL);
        }
-       txg_list_create(&vd->vdev_ms_list,
+       txg_list_create(&vd->vdev_ms_list, spa,
            offsetof(struct metaslab, ms_txg_node));
-       txg_list_create(&vd->vdev_dtl_list,
+       txg_list_create(&vd->vdev_dtl_list, spa,
            offsetof(struct vdev, vdev_dtl_node));
        vd->vdev_stat.vs_timestamp = gethrtime();
        vdev_queue_init(vd);
@@ -391,6 +567,11 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
        char *type;
        uint64_t guid = 0, islog, nparity;
        vdev_t *vd;
+       vdev_indirect_config_t *vic;
+       char *tmp = NULL;
+       int rc;
+       vdev_alloc_bias_t alloc_bias = VDEV_BIAS_NONE;
+       boolean_t top_level = (parent && !parent->vdev_parent);
 
        ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
 
@@ -477,13 +658,48 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
        }
        ASSERT(nparity != -1ULL);
 
+       /*
+        * If creating a top-level vdev, check for allocation classes input
+        */
+       if (top_level && alloctype == VDEV_ALLOC_ADD) {
+               char *bias;
+
+               if (nvlist_lookup_string(nv, ZPOOL_CONFIG_ALLOCATION_BIAS,
+                   &bias) == 0) {
+                       alloc_bias = vdev_derive_alloc_bias(bias);
+
+                       /* spa_vdev_add() expects feature to be enabled */
+                       if (spa->spa_load_state != SPA_LOAD_CREATE &&
+                           !spa_feature_is_enabled(spa,
+                           SPA_FEATURE_ALLOCATION_CLASSES)) {
+                               return (SET_ERROR(ENOTSUP));
+                       }
+               }
+       }
+
        vd = vdev_alloc_common(spa, id, guid, ops);
+       vic = &vd->vdev_indirect_config;
 
        vd->vdev_islog = islog;
        vd->vdev_nparity = nparity;
+       if (top_level && alloc_bias != VDEV_BIAS_NONE)
+               vd->vdev_alloc_bias = alloc_bias;
 
        if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PATH, &vd->vdev_path) == 0)
                vd->vdev_path = spa_strdup(vd->vdev_path);
+
+       /*
+        * ZPOOL_CONFIG_AUX_STATE = "external" means we previously forced a
+        * fault on a vdev and want it to persist across imports (like with
+        * zpool offline -f).
+        */
+       rc = nvlist_lookup_string(nv, ZPOOL_CONFIG_AUX_STATE, &tmp);
+       if (rc == 0 && tmp != NULL && strcmp(tmp, "external") == 0) {
+               vd->vdev_stat.vs_aux = VDEV_AUX_EXTERNAL;
+               vd->vdev_faulted = 1;
+               vd->vdev_label_aux = VDEV_AUX_EXTERNAL;
+       }
+
        if (nvlist_lookup_string(nv, ZPOOL_CONFIG_DEVID, &vd->vdev_devid) == 0)
                vd->vdev_devid = spa_strdup(vd->vdev_devid);
        if (nvlist_lookup_string(nv, ZPOOL_CONFIG_PHYS_PATH,
@@ -505,6 +721,16 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
            &vd->vdev_wholedisk) != 0)
                vd->vdev_wholedisk = -1ULL;
 
+       ASSERT0(vic->vic_mapping_object);
+       (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_INDIRECT_OBJECT,
+           &vic->vic_mapping_object);
+       ASSERT0(vic->vic_births_object);
+       (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_INDIRECT_BIRTHS,
+           &vic->vic_births_object);
+       ASSERT3U(vic->vic_prev_indirect_vdev, ==, UINT64_MAX);
+       (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_PREV_INDIRECT_VDEV,
+           &vic->vic_prev_indirect_vdev);
+
        /*
         * Look for the 'not present' flag.  This will only be set if the device
         * was not present at the time of import.
@@ -526,7 +752,7 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
        /*
         * If we're a top-level vdev, try to load the allocation parameters.
         */
-       if (parent && !parent->vdev_parent &&
+       if (top_level &&
            (alloctype == VDEV_ALLOC_LOAD || alloctype == VDEV_ALLOC_SPLIT)) {
                (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_METASLAB_ARRAY,
                    &vd->vdev_ms_array);
@@ -542,13 +768,12 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
                ASSERT0(vd->vdev_top_zap);
        }
 
-       if (parent && !parent->vdev_parent && alloctype != VDEV_ALLOC_ATTACH) {
+       if (top_level && alloctype != VDEV_ALLOC_ATTACH) {
                ASSERT(alloctype == VDEV_ALLOC_LOAD ||
                    alloctype == VDEV_ALLOC_ADD ||
                    alloctype == VDEV_ALLOC_SPLIT ||
                    alloctype == VDEV_ALLOC_ROOTPOOL);
-               vd->vdev_mg = metaslab_group_create(islog ?
-                   spa_log_class(spa) : spa_normal_class(spa), vd);
+               /* Note: metaslab_group_create() is now deferred */
        }
 
        if (vd->vdev_ops->vdev_op_leaf &&
@@ -587,13 +812,21 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
                (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_RESILVER_TXG,
                    &vd->vdev_resilver_txg);
 
+               if (nvlist_exists(nv, ZPOOL_CONFIG_RESILVER_DEFER))
+                       vdev_set_deferred_resilver(spa, vd);
+
                /*
-                * When importing a pool, we want to ignore the persistent fault
-                * state, as the diagnosis made on another system may not be
-                * valid in the current context.  Local vdevs will
-                * remain in the faulted state.
+                * In general, when importing a pool we want to ignore the
+                * persistent fault state, as the diagnosis made on another
+                * system may not be valid in the current context.  The only
+                * exception is if we forced a vdev to a persistently faulted
+                * state with 'zpool offline -f'.  The persistent fault will
+                * remain across imports until cleared.
+                *
+                * Local vdevs will remain in the faulted state.
                 */
-               if (spa_load_state(spa) == SPA_LOAD_OPEN) {
+               if (spa_load_state(spa) == SPA_LOAD_OPEN ||
+                   spa_load_state(spa) == SPA_LOAD_IMPORT) {
                        (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_FAULTED,
                            &vd->vdev_faulted);
                        (void) nvlist_lookup_uint64(nv, ZPOOL_CONFIG_DEGRADED,
@@ -610,6 +843,8 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
                                    ZPOOL_CONFIG_AUX_STATE, &aux) == 0 &&
                                    strcmp(aux, "external") == 0)
                                        vd->vdev_label_aux = VDEV_AUX_EXTERNAL;
+                               else
+                                       vd->vdev_faulted = 0ULL;
                        }
                }
        }
@@ -627,8 +862,20 @@ vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *nv, vdev_t *parent, uint_t id,
 void
 vdev_free(vdev_t *vd)
 {
-       int c, t;
        spa_t *spa = vd->vdev_spa;
+       ASSERT3P(vd->vdev_initialize_thread, ==, NULL);
+
+       /*
+        * Scan queues are normally destroyed at the end of a scan. If the
+        * queue exists here, that implies the vdev is being removed while
+        * the scan is still running.
+        */
+       if (vd->vdev_scan_io_queue != NULL) {
+               mutex_enter(&vd->vdev_scan_io_queue_lock);
+               dsl_scan_io_queue_destroy(vd->vdev_scan_io_queue);
+               vd->vdev_scan_io_queue = NULL;
+               mutex_exit(&vd->vdev_scan_io_queue_lock);
+       }
 
        /*
         * vdev_free() implies closing the vdev first.  This is simpler than
@@ -642,11 +889,12 @@ vdev_free(vdev_t *vd)
        /*
         * Free all children.
         */
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_free(vd->vdev_child[c]);
 
        ASSERT(vd->vdev_child == NULL);
        ASSERT(vd->vdev_guid_sum == vd->vdev_guid);
+       ASSERT(vd->vdev_initialize_thread == NULL);
 
        /*
         * Discard allocation state.
@@ -696,16 +944,40 @@ vdev_free(vdev_t *vd)
 
        mutex_enter(&vd->vdev_dtl_lock);
        space_map_close(vd->vdev_dtl_sm);
-       for (t = 0; t < DTL_TYPES; t++) {
+       for (int t = 0; t < DTL_TYPES; t++) {
                range_tree_vacate(vd->vdev_dtl[t], NULL, NULL);
                range_tree_destroy(vd->vdev_dtl[t]);
        }
        mutex_exit(&vd->vdev_dtl_lock);
 
-       mutex_destroy(&vd->vdev_queue_lock);
+       EQUIV(vd->vdev_indirect_births != NULL,
+           vd->vdev_indirect_mapping != NULL);
+       if (vd->vdev_indirect_births != NULL) {
+               vdev_indirect_mapping_close(vd->vdev_indirect_mapping);
+               vdev_indirect_births_close(vd->vdev_indirect_births);
+       }
+
+       if (vd->vdev_obsolete_sm != NULL) {
+               ASSERT(vd->vdev_removing ||
+                   vd->vdev_ops == &vdev_indirect_ops);
+               space_map_close(vd->vdev_obsolete_sm);
+               vd->vdev_obsolete_sm = NULL;
+       }
+       range_tree_destroy(vd->vdev_obsolete_segments);
+       rw_destroy(&vd->vdev_indirect_rwlock);
+       mutex_destroy(&vd->vdev_obsolete_lock);
+
        mutex_destroy(&vd->vdev_dtl_lock);
        mutex_destroy(&vd->vdev_stat_lock);
        mutex_destroy(&vd->vdev_probe_lock);
+       mutex_destroy(&vd->vdev_scan_io_queue_lock);
+       mutex_destroy(&vd->vdev_initialize_lock);
+       mutex_destroy(&vd->vdev_initialize_io_lock);
+       cv_destroy(&vd->vdev_initialize_io_cv);
+       cv_destroy(&vd->vdev_initialize_cv);
+
+       zfs_ratelimit_fini(&vd->vdev_delay_rl);
+       zfs_ratelimit_fini(&vd->vdev_checksum_rl);
 
        if (vd == spa->spa_root_vdev)
                spa->spa_root_vdev = NULL;
@@ -748,6 +1020,12 @@ vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
        if (tvd->vdev_mg != NULL)
                tvd->vdev_mg->mg_vd = tvd;
 
+       tvd->vdev_checkpoint_sm = svd->vdev_checkpoint_sm;
+       svd->vdev_checkpoint_sm = NULL;
+
+       tvd->vdev_alloc_bias = svd->vdev_alloc_bias;
+       svd->vdev_alloc_bias = VDEV_BIAS_NONE;
+
        tvd->vdev_stat.vs_alloc = svd->vdev_stat.vs_alloc;
        tvd->vdev_stat.vs_space = svd->vdev_stat.vs_space;
        tvd->vdev_stat.vs_dspace = svd->vdev_stat.vs_dspace;
@@ -756,6 +1034,32 @@ vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
        svd->vdev_stat.vs_space = 0;
        svd->vdev_stat.vs_dspace = 0;
 
+       /*
+        * State which may be set on a top-level vdev that's in the
+        * process of being removed.
+        */
+       ASSERT0(tvd->vdev_indirect_config.vic_births_object);
+       ASSERT0(tvd->vdev_indirect_config.vic_mapping_object);
+       ASSERT3U(tvd->vdev_indirect_config.vic_prev_indirect_vdev, ==, -1ULL);
+       ASSERT3P(tvd->vdev_indirect_mapping, ==, NULL);
+       ASSERT3P(tvd->vdev_indirect_births, ==, NULL);
+       ASSERT3P(tvd->vdev_obsolete_sm, ==, NULL);
+       ASSERT0(tvd->vdev_removing);
+       tvd->vdev_removing = svd->vdev_removing;
+       tvd->vdev_indirect_config = svd->vdev_indirect_config;
+       tvd->vdev_indirect_mapping = svd->vdev_indirect_mapping;
+       tvd->vdev_indirect_births = svd->vdev_indirect_births;
+       range_tree_swap(&svd->vdev_obsolete_segments,
+           &tvd->vdev_obsolete_segments);
+       tvd->vdev_obsolete_sm = svd->vdev_obsolete_sm;
+       svd->vdev_indirect_config.vic_mapping_object = 0;
+       svd->vdev_indirect_config.vic_births_object = 0;
+       svd->vdev_indirect_config.vic_prev_indirect_vdev = -1ULL;
+       svd->vdev_indirect_mapping = NULL;
+       svd->vdev_indirect_births = NULL;
+       svd->vdev_obsolete_sm = NULL;
+       svd->vdev_removing = 0;
+
        for (t = 0; t < TXG_SIZE; t++) {
                while ((msp = txg_list_remove(&svd->vdev_ms_list, t)) != NULL)
                        (void) txg_list_add(&tvd->vdev_ms_list, msp, t);
@@ -780,19 +1084,19 @@ vdev_top_transfer(vdev_t *svd, vdev_t *tvd)
 
        tvd->vdev_islog = svd->vdev_islog;
        svd->vdev_islog = 0;
+
+       dsl_scan_io_queue_vdev_xfer(svd, tvd);
 }
 
 static void
 vdev_top_update(vdev_t *tvd, vdev_t *vd)
 {
-       int c;
-
        if (vd == NULL)
                return;
 
        vd->vdev_top = tvd;
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_top_update(tvd, vd->vdev_child[c]);
 }
 
@@ -813,6 +1117,7 @@ vdev_add_parent(vdev_t *cvd, vdev_ops_t *ops)
        mvd->vdev_asize = cvd->vdev_asize;
        mvd->vdev_min_asize = cvd->vdev_min_asize;
        mvd->vdev_max_asize = cvd->vdev_max_asize;
+       mvd->vdev_psize = cvd->vdev_psize;
        mvd->vdev_ashift = cvd->vdev_ashift;
        mvd->vdev_state = cvd->vdev_state;
        mvd->vdev_crtxg = cvd->vdev_crtxg;
@@ -883,6 +1188,55 @@ vdev_remove_parent(vdev_t *cvd)
        vdev_free(mvd);
 }
 
+static void
+vdev_metaslab_group_create(vdev_t *vd)
+{
+       spa_t *spa = vd->vdev_spa;
+
+       /*
+        * metaslab_group_create was delayed until allocation bias was available
+        */
+       if (vd->vdev_mg == NULL) {
+               metaslab_class_t *mc;
+
+               if (vd->vdev_islog && vd->vdev_alloc_bias == VDEV_BIAS_NONE)
+                       vd->vdev_alloc_bias = VDEV_BIAS_LOG;
+
+               ASSERT3U(vd->vdev_islog, ==,
+                   (vd->vdev_alloc_bias == VDEV_BIAS_LOG));
+
+               switch (vd->vdev_alloc_bias) {
+               case VDEV_BIAS_LOG:
+                       mc = spa_log_class(spa);
+                       break;
+               case VDEV_BIAS_SPECIAL:
+                       mc = spa_special_class(spa);
+                       break;
+               case VDEV_BIAS_DEDUP:
+                       mc = spa_dedup_class(spa);
+                       break;
+               default:
+                       mc = spa_normal_class(spa);
+               }
+
+               vd->vdev_mg = metaslab_group_create(mc, vd,
+                   spa->spa_alloc_count);
+
+               /*
+                * The spa ashift values currently only reflect the
+                * general vdev classes. Class destination is late
+                * binding so ashift checking had to wait until now
+                */
+               if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
+                   mc == spa_normal_class(spa) && vd->vdev_aux == NULL) {
+                       if (vd->vdev_ashift > spa->spa_max_ashift)
+                               spa->spa_max_ashift = vd->vdev_ashift;
+                       if (vd->vdev_ashift < spa->spa_min_ashift)
+                               spa->spa_min_ashift = vd->vdev_ashift;
+               }
+       }
+}
+
 int
 vdev_metaslab_init(vdev_t *vd, uint64_t txg)
 {
@@ -893,6 +1247,7 @@ vdev_metaslab_init(vdev_t *vd, uint64_t txg)
        uint64_t newc = vd->vdev_asize >> vd->vdev_ms_shift;
        metaslab_t **mspp;
        int error;
+       boolean_t expanding = (oldc != 0);
 
        ASSERT(txg == 0 || spa_config_held(spa, SCL_ALLOC, RW_WRITER));
 
@@ -904,42 +1259,54 @@ vdev_metaslab_init(vdev_t *vd, uint64_t txg)
 
        ASSERT(!vd->vdev_ishole);
 
-       /*
-        * Compute the raidz-deflation ratio.  Note, we hard-code
-        * in 128k (1 << 17) because it is the "typical" blocksize.
-        * Even though SPA_MAXBLOCKSIZE changed, this algorithm can not change,
-        * otherwise it would inconsistently account for existing bp's.
-        */
-       vd->vdev_deflate_ratio = (1 << 17) /
-           (vdev_psize_to_asize(vd, 1 << 17) >> SPA_MINBLOCKSHIFT);
-
        ASSERT(oldc <= newc);
 
        mspp = vmem_zalloc(newc * sizeof (*mspp), KM_SLEEP);
 
-       if (oldc != 0) {
+       if (expanding) {
                bcopy(vd->vdev_ms, mspp, oldc * sizeof (*mspp));
                vmem_free(vd->vdev_ms, oldc * sizeof (*mspp));
        }
 
        vd->vdev_ms = mspp;
        vd->vdev_ms_count = newc;
-
        for (m = oldc; m < newc; m++) {
                uint64_t object = 0;
 
-               if (txg == 0) {
+               /*
+                * vdev_ms_array may be 0 if we are creating the "fake"
+                * metaslabs for an indirect vdev for zdb's leak detection.
+                * See zdb_leak_init().
+                */
+               if (txg == 0 && vd->vdev_ms_array != 0) {
                        error = dmu_read(mos, vd->vdev_ms_array,
                            m * sizeof (uint64_t), sizeof (uint64_t), &object,
                            DMU_READ_PREFETCH);
-                       if (error)
+                       if (error != 0) {
+                               vdev_dbgmsg(vd, "unable to read the metaslab "
+                                   "array [error=%d]", error);
                                return (error);
+                       }
                }
 
+#ifndef _KERNEL
+               /*
+                * To accomodate zdb_leak_init() fake indirect
+                * metaslabs, we allocate a metaslab group for
+                * indirect vdevs which normally don't have one.
+                */
+               if (vd->vdev_mg == NULL) {
+                       ASSERT0(vdev_is_concrete(vd));
+                       vdev_metaslab_group_create(vd);
+               }
+#endif
                error = metaslab_init(vd->vdev_mg, m, object, txg,
                    &(vd->vdev_ms[m]));
-               if (error)
+               if (error != 0) {
+                       vdev_dbgmsg(vd, "metaslab_init failed [error=%d]",
+                           error);
                        return (error);
+               }
        }
 
        if (txg == 0)
@@ -950,8 +1317,9 @@ vdev_metaslab_init(vdev_t *vd, uint64_t txg)
         * the metaslabs since we want to ensure that no new
         * allocations are performed on this device.
         */
-       if (oldc == 0 && !vd->vdev_removing)
+       if (!expanding && !vd->vdev_removing) {
                metaslab_group_activate(vd->vdev_mg);
+       }
 
        if (txg == 0)
                spa_config_exit(spa, SCL_ALLOC, FTAG);
@@ -962,12 +1330,26 @@ vdev_metaslab_init(vdev_t *vd, uint64_t txg)
 void
 vdev_metaslab_fini(vdev_t *vd)
 {
-       uint64_t m;
-       uint64_t count = vd->vdev_ms_count;
+       if (vd->vdev_checkpoint_sm != NULL) {
+               ASSERT(spa_feature_is_active(vd->vdev_spa,
+                   SPA_FEATURE_POOL_CHECKPOINT));
+               space_map_close(vd->vdev_checkpoint_sm);
+               /*
+                * Even though we close the space map, we need to set its
+                * pointer to NULL. The reason is that vdev_metaslab_fini()
+                * may be called multiple times for certain operations
+                * (i.e. when destroying a pool) so we need to ensure that
+                * this clause never executes twice. This logic is similar
+                * to the one used for the vdev_ms clause below.
+                */
+               vd->vdev_checkpoint_sm = NULL;
+       }
 
        if (vd->vdev_ms != NULL) {
+               uint64_t count = vd->vdev_ms_count;
+
                metaslab_group_passivate(vd->vdev_mg);
-               for (m = 0; m < count; m++) {
+               for (uint64_t m = 0; m < count; m++) {
                        metaslab_t *msp = vd->vdev_ms[m];
 
                        if (msp != NULL)
@@ -975,8 +1357,10 @@ vdev_metaslab_fini(vdev_t *vd)
                }
                vmem_free(vd->vdev_ms, count * sizeof (metaslab_t *));
                vd->vdev_ms = NULL;
-       }
 
+               vd->vdev_ms_count = 0;
+       }
+       ASSERT0(vd->vdev_ms_count);
        ASSERT3U(vd->vdev_pending_fastwrite, ==, 0);
 }
 
@@ -1022,8 +1406,9 @@ vdev_probe_done(zio_t *zio)
                        zio->io_error = 0;
                } else {
                        ASSERT(zio->io_error != 0);
+                       vdev_dbgmsg(vd, "failed probe");
                        zfs_ereport_post(FM_EREPORT_ZFS_PROBE_FAILURE,
-                           spa, vd, NULL, 0, 0);
+                           spa, vd, NULL, NULL, 0, 0);
                        zio->io_error = SET_ERROR(ENXIO);
                }
 
@@ -1054,7 +1439,6 @@ vdev_probe(vdev_t *vd, zio_t *zio)
        spa_t *spa = vd->vdev_spa;
        vdev_probe_stats_t *vps = NULL;
        zio_t *pio;
-       int l;
 
        ASSERT(vd->vdev_ops->vdev_op_leaf);
 
@@ -1124,7 +1508,7 @@ vdev_probe(vdev_t *vd, zio_t *zio)
                return (NULL);
        }
 
-       for (l = 1; l < VDEV_LABELS; l++) {
+       for (int l = 1; l < VDEV_LABELS; l++) {
                zio_nowait(zio_read_phys(pio, vd,
                    vdev_label_offset(vd->vdev_psize, l,
                    offsetof(vdev_label_t, vl_pad2)), VDEV_PAD_SIZE,
@@ -1153,14 +1537,12 @@ vdev_open_child(void *arg)
 static boolean_t
 vdev_uses_zvols(vdev_t *vd)
 {
-       int c;
-
 #ifdef _KERNEL
        if (zvol_is_zvol(vd->vdev_path))
                return (B_TRUE);
 #endif
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                if (vdev_uses_zvols(vd->vdev_child[c]))
                        return (B_TRUE);
 
@@ -1172,7 +1554,6 @@ vdev_open_children(vdev_t *vd)
 {
        taskq_t *tq;
        int children = vd->vdev_children;
-       int c;
 
        /*
         * in order to handle pools on top of zvols, do the opens
@@ -1181,7 +1562,7 @@ vdev_open_children(vdev_t *vd)
         */
        if (vdev_uses_zvols(vd)) {
 retry_sync:
-               for (c = 0; c < children; c++)
+               for (int c = 0; c < children; c++)
                        vd->vdev_child[c]->vdev_open_error =
                            vdev_open(vd->vdev_child[c]);
        } else {
@@ -1190,7 +1571,7 @@ retry_sync:
                if (tq == NULL)
                        goto retry_sync;
 
-               for (c = 0; c < children; c++)
+               for (int c = 0; c < children; c++)
                        VERIFY(taskq_dispatch(tq, vdev_open_child,
                            vd->vdev_child[c], TQ_SLEEP) != TASKQID_INVALID);
 
@@ -1199,10 +1580,25 @@ retry_sync:
 
        vd->vdev_nonrot = B_TRUE;
 
-       for (c = 0; c < children; c++)
+       for (int c = 0; c < children; c++)
                vd->vdev_nonrot &= vd->vdev_child[c]->vdev_nonrot;
 }
 
+/*
+ * Compute the raidz-deflation ratio.  Note, we hard-code
+ * in 128k (1 << 17) because it is the "typical" blocksize.
+ * Even though SPA_MAXBLOCKSIZE changed, this algorithm can not change,
+ * otherwise it would inconsistently account for existing bp's.
+ */
+static void
+vdev_set_deflate_ratio(vdev_t *vd)
+{
+       if (vd == vd->vdev_top && !vd->vdev_ishole && vd->vdev_ashift != 0) {
+               vd->vdev_deflate_ratio = (1 << 17) /
+                   (vdev_psize_to_asize(vd, 1 << 17) >> SPA_MINBLOCKSHIFT);
+       }
+}
+
 /*
  * Prepare a virtual device for access.
  */
@@ -1215,7 +1611,6 @@ vdev_open(vdev_t *vd)
        uint64_t max_osize = 0;
        uint64_t asize, max_asize, psize;
        uint64_t ashift = 0;
-       int c;
 
        ASSERT(vd->vdev_open_thread == curthread ||
            spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
@@ -1260,8 +1655,13 @@ vdev_open(vdev_t *vd)
                    vd->vdev_stat.vs_aux != VDEV_AUX_OPEN_FAILED)
                        vd->vdev_removed = B_FALSE;
 
-               vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
-                   vd->vdev_stat.vs_aux);
+               if (vd->vdev_stat.vs_aux == VDEV_AUX_CHILDREN_OFFLINE) {
+                       vdev_set_state(vd, B_TRUE, VDEV_STATE_OFFLINE,
+                           vd->vdev_stat.vs_aux);
+               } else {
+                       vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
+                           vd->vdev_stat.vs_aux);
+               }
                return (error);
        }
 
@@ -1294,7 +1694,7 @@ vdev_open(vdev_t *vd)
        if (vd->vdev_ishole || vd->vdev_ops == &vdev_missing_ops)
                return (0);
 
-       for (c = 0; c < vd->vdev_children; c++) {
+       for (int c = 0; c < vd->vdev_children; c++) {
                if (vd->vdev_child[c]->vdev_state != VDEV_STATE_HEALTHY) {
                        vdev_set_state(vd, B_TRUE, VDEV_STATE_DEGRADED,
                            VDEV_AUX_NONE);
@@ -1327,10 +1727,17 @@ vdev_open(vdev_t *vd)
                max_asize = max_osize;
        }
 
+       /*
+        * If the vdev was expanded, record this so that we can re-create the
+        * uberblock rings in labels {2,3}, during the next sync.
+        */
+       if ((psize > vd->vdev_psize) && (vd->vdev_psize != 0))
+               vd->vdev_copy_uberblocks = B_TRUE;
+
        vd->vdev_psize = psize;
 
        /*
-        * Make sure the allocatable size hasn't shrunk.
+        * Make sure the allocatable size hasn't shrunk too much.
         */
        if (asize < vd->vdev_min_asize) {
                vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
@@ -1345,8 +1752,15 @@ vdev_open(vdev_t *vd)
                 */
                vd->vdev_asize = asize;
                vd->vdev_max_asize = max_asize;
-               if (vd->vdev_ashift == 0)
-                       vd->vdev_ashift = ashift;
+               if (vd->vdev_ashift == 0) {
+                       vd->vdev_ashift = ashift; /* use detected value */
+               }
+               if (vd->vdev_ashift != 0 && (vd->vdev_ashift < ASHIFT_MIN ||
+                   vd->vdev_ashift > ASHIFT_MAX)) {
+                       vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
+                           VDEV_AUX_BAD_ASHIFT);
+                       return (SET_ERROR(EDOM));
+               }
        } else {
                /*
                 * Detect if the alignment requirement has increased.
@@ -1356,19 +1770,28 @@ vdev_open(vdev_t *vd)
                if (ashift > vd->vdev_top->vdev_ashift &&
                    vd->vdev_ops->vdev_op_leaf) {
                        zfs_ereport_post(FM_EREPORT_ZFS_DEVICE_BAD_ASHIFT,
-                           spa, vd, NULL, 0, 0);
+                           spa, vd, NULL, NULL, 0, 0);
                }
 
                vd->vdev_max_asize = max_asize;
        }
 
        /*
-        * If all children are healthy and the asize has increased,
-        * then we've experienced dynamic LUN growth.  If automatic
-        * expansion is enabled then use the additional space.
+        * If all children are healthy we update asize if either:
+        * The asize has increased, due to a device expansion caused by dynamic
+        * LUN growth or vdev replacement, and automatic expansion is enabled;
+        * making the additional space available.
+        *
+        * The asize has decreased, due to a device shrink usually caused by a
+        * vdev replace with a smaller device. This ensures that calculations
+        * based of max_asize and asize e.g. esize are always valid. It's safe
+        * to do this as we've already validated that asize is greater than
+        * vdev_min_asize.
         */
-       if (vd->vdev_state == VDEV_STATE_HEALTHY && asize > vd->vdev_asize &&
-           (vd->vdev_expanding || spa->spa_autoexpand))
+       if (vd->vdev_state == VDEV_STATE_HEALTHY &&
+           ((asize > vd->vdev_asize &&
+           (vd->vdev_expanding || spa->spa_autoexpand)) ||
+           (asize < vd->vdev_asize)))
                vd->vdev_asize = asize;
 
        vdev_set_min_asize(vd);
@@ -1386,9 +1809,13 @@ vdev_open(vdev_t *vd)
 
        /*
         * Track the min and max ashift values for normal data devices.
+        *
+        * DJB - TBD these should perhaps be tracked per allocation class
+        * (e.g. spa_min_ashift is used to round up post compression buffers)
         */
        if (vd->vdev_top == vd && vd->vdev_ashift != 0 &&
-           !vd->vdev_islog && vd->vdev_aux == NULL) {
+           vd->vdev_alloc_bias == VDEV_BIAS_NONE &&
+           vd->vdev_aux == NULL) {
                if (vd->vdev_ashift > spa->spa_max_ashift)
                        spa->spa_max_ashift = vd->vdev_ashift;
                if (vd->vdev_ashift < spa->spa_min_ashift)
@@ -1401,38 +1828,42 @@ vdev_open(vdev_t *vd)
         * since this would just restart the scrub we are already doing.
         */
        if (vd->vdev_ops->vdev_op_leaf && !spa->spa_scrub_reopen &&
-           vdev_resilver_needed(vd, NULL, NULL))
-               spa_async_request(spa, SPA_ASYNC_RESILVER);
+           vdev_resilver_needed(vd, NULL, NULL)) {
+               if (dsl_scan_resilvering(spa->spa_dsl_pool) &&
+                   spa_feature_is_enabled(spa, SPA_FEATURE_RESILVER_DEFER))
+                       vdev_set_deferred_resilver(spa, vd);
+               else
+                       spa_async_request(spa, SPA_ASYNC_RESILVER);
+       }
 
        return (0);
 }
 
 /*
  * Called once the vdevs are all opened, this routine validates the label
- * contents.  This needs to be done before vdev_load() so that we don't
+ * contents. This needs to be done before vdev_load() so that we don't
  * inadvertently do repair I/Os to the wrong device.
  *
- * If 'strict' is false ignore the spa guid check. This is necessary because
- * if the machine crashed during a re-guid the new guid might have been written
- * to all of the vdev labels, but not the cached config. The strict check
- * will be performed when the pool is opened again using the mos config.
- *
  * This function will only return failure if one of the vdevs indicates that it
  * has since been destroyed or exported.  This is only possible if
  * /etc/zfs/zpool.cache was readonly at the time.  Otherwise, the vdev state
  * will be updated but the function will return 0.
  */
 int
-vdev_validate(vdev_t *vd, boolean_t strict)
+vdev_validate(vdev_t *vd)
 {
        spa_t *spa = vd->vdev_spa;
        nvlist_t *label;
-       uint64_t guid = 0, top_guid;
+       uint64_t guid = 0, aux_guid = 0, top_guid;
        uint64_t state;
-       int c;
+       nvlist_t *nvl;
+       uint64_t txg;
+
+       if (vdev_validate_skip)
+               return (0);
 
-       for (c = 0; c < vd->vdev_children; c++)
-               if (vdev_validate(vd->vdev_child[c], strict) != 0)
+       for (uint64_t c = 0; c < vd->vdev_children; c++)
+               if (vdev_validate(vd->vdev_child[c]) != 0)
                        return (SET_ERROR(EBADF));
 
        /*
@@ -1440,99 +1871,280 @@ vdev_validate(vdev_t *vd, boolean_t strict)
         * any further validation.  Otherwise, label I/O will fail and we will
         * overwrite the previous state.
         */
-       if (vd->vdev_ops->vdev_op_leaf && vdev_readable(vd)) {
-               uint64_t aux_guid = 0;
-               nvlist_t *nvl;
-               uint64_t txg = spa_last_synced_txg(spa) != 0 ?
-                   spa_last_synced_txg(spa) : -1ULL;
+       if (!vd->vdev_ops->vdev_op_leaf || !vdev_readable(vd))
+               return (0);
 
-               if ((label = vdev_label_read_config(vd, txg)) == NULL) {
-                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_BAD_LABEL);
-                       return (0);
-               }
+       /*
+        * If we are performing an extreme rewind, we allow for a label that
+        * was modified at a point after the current txg.
+        * If config lock is not held do not check for the txg. spa_sync could
+        * be updating the vdev's label before updating spa_last_synced_txg.
+        */
+       if (spa->spa_extreme_rewind || spa_last_synced_txg(spa) == 0 ||
+           spa_config_held(spa, SCL_CONFIG, RW_WRITER) != SCL_CONFIG)
+               txg = UINT64_MAX;
+       else
+               txg = spa_last_synced_txg(spa);
 
-               /*
-                * Determine if this vdev has been split off into another
-                * pool.  If so, then refuse to open it.
-                */
-               if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_SPLIT_GUID,
-                   &aux_guid) == 0 && aux_guid == spa_guid(spa)) {
-                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_SPLIT_POOL);
-                       nvlist_free(label);
-                       return (0);
-               }
+       if ((label = vdev_label_read_config(vd, txg)) == NULL) {
+               vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_BAD_LABEL);
+               vdev_dbgmsg(vd, "vdev_validate: failed reading config for "
+                   "txg %llu", (u_longlong_t)txg);
+               return (0);
+       }
 
-               if (strict && (nvlist_lookup_uint64(label,
-                   ZPOOL_CONFIG_POOL_GUID, &guid) != 0 ||
-                   guid != spa_guid(spa))) {
-                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_CORRUPT_DATA);
-                       nvlist_free(label);
-                       return (0);
-               }
+       /*
+        * Determine if this vdev has been split off into another
+        * pool.  If so, then refuse to open it.
+        */
+       if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_SPLIT_GUID,
+           &aux_guid) == 0 && aux_guid == spa_guid(spa)) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_SPLIT_POOL);
+               nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: vdev split into other pool");
+               return (0);
+       }
 
-               if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_VDEV_TREE, &nvl)
-                   != 0 || nvlist_lookup_uint64(nvl, ZPOOL_CONFIG_ORIG_GUID,
-                   &aux_guid) != 0)
-                       aux_guid = 0;
+       if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_GUID, &guid) != 0) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_CORRUPT_DATA);
+               nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
+                   ZPOOL_CONFIG_POOL_GUID);
+               return (0);
+       }
 
-               /*
-                * If this vdev just became a top-level vdev because its
-                * sibling was detached, it will have adopted the parent's
-                * vdev guid -- but the label may or may not be on disk yet.
-                * Fortunately, either version of the label will have the
-                * same top guid, so if we're a top-level vdev, we can
-                * safely compare to that instead.
-                *
-                * If we split this vdev off instead, then we also check the
-                * original pool's guid.  We don't want to consider the vdev
-                * corrupt if it is partway through a split operation.
-                */
-               if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID,
-                   &guid) != 0 ||
-                   nvlist_lookup_uint64(label, ZPOOL_CONFIG_TOP_GUID,
-                   &top_guid) != 0 ||
-                   ((vd->vdev_guid != guid && vd->vdev_guid != aux_guid) &&
-                   (vd->vdev_guid != top_guid || vd != vd->vdev_top))) {
-                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
-                           VDEV_AUX_CORRUPT_DATA);
-                       nvlist_free(label);
-                       return (0);
+       /*
+        * If config is not trusted then ignore the spa guid check. This is
+        * necessary because if the machine crashed during a re-guid the new
+        * guid might have been written to all of the vdev labels, but not the
+        * cached config. The check will be performed again once we have the
+        * trusted config from the MOS.
+        */
+       if (spa->spa_trust_config && guid != spa_guid(spa)) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_CORRUPT_DATA);
+               nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: vdev label pool_guid doesn't "
+                   "match config (%llu != %llu)", (u_longlong_t)guid,
+                   (u_longlong_t)spa_guid(spa));
+               return (0);
+       }
+
+       if (nvlist_lookup_nvlist(label, ZPOOL_CONFIG_VDEV_TREE, &nvl)
+           != 0 || nvlist_lookup_uint64(nvl, ZPOOL_CONFIG_ORIG_GUID,
+           &aux_guid) != 0)
+               aux_guid = 0;
+
+       if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_GUID, &guid) != 0) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_CORRUPT_DATA);
+               nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
+                   ZPOOL_CONFIG_GUID);
+               return (0);
+       }
+
+       if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_TOP_GUID, &top_guid)
+           != 0) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_CORRUPT_DATA);
+               nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
+                   ZPOOL_CONFIG_TOP_GUID);
+               return (0);
+       }
+
+       /*
+        * If this vdev just became a top-level vdev because its sibling was
+        * detached, it will have adopted the parent's vdev guid -- but the
+        * label may or may not be on disk yet. Fortunately, either version
+        * of the label will have the same top guid, so if we're a top-level
+        * vdev, we can safely compare to that instead.
+        * However, if the config comes from a cachefile that failed to update
+        * after the detach, a top-level vdev will appear as a non top-level
+        * vdev in the config. Also relax the constraints if we perform an
+        * extreme rewind.
+        *
+        * If we split this vdev off instead, then we also check the
+        * original pool's guid. We don't want to consider the vdev
+        * corrupt if it is partway through a split operation.
+        */
+       if (vd->vdev_guid != guid && vd->vdev_guid != aux_guid) {
+               boolean_t mismatch = B_FALSE;
+               if (spa->spa_trust_config && !spa->spa_extreme_rewind) {
+                       if (vd != vd->vdev_top || vd->vdev_guid != top_guid)
+                               mismatch = B_TRUE;
+               } else {
+                       if (vd->vdev_guid != top_guid &&
+                           vd->vdev_top->vdev_guid != guid)
+                               mismatch = B_TRUE;
                }
 
-               if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
-                   &state) != 0) {
+               if (mismatch) {
                        vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
                            VDEV_AUX_CORRUPT_DATA);
                        nvlist_free(label);
+                       vdev_dbgmsg(vd, "vdev_validate: config guid "
+                           "doesn't match label guid");
+                       vdev_dbgmsg(vd, "CONFIG: guid %llu, top_guid %llu",
+                           (u_longlong_t)vd->vdev_guid,
+                           (u_longlong_t)vd->vdev_top->vdev_guid);
+                       vdev_dbgmsg(vd, "LABEL: guid %llu, top_guid %llu, "
+                           "aux_guid %llu", (u_longlong_t)guid,
+                           (u_longlong_t)top_guid, (u_longlong_t)aux_guid);
                        return (0);
                }
+       }
 
+       if (nvlist_lookup_uint64(label, ZPOOL_CONFIG_POOL_STATE,
+           &state) != 0) {
+               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                   VDEV_AUX_CORRUPT_DATA);
                nvlist_free(label);
+               vdev_dbgmsg(vd, "vdev_validate: '%s' missing from label",
+                   ZPOOL_CONFIG_POOL_STATE);
+               return (0);
+       }
 
-               /*
-                * If this is a verbatim import, no need to check the
-                * state of the pool.
-                */
-               if (!(spa->spa_import_flags & ZFS_IMPORT_VERBATIM) &&
-                   spa_load_state(spa) == SPA_LOAD_OPEN &&
-                   state != POOL_STATE_ACTIVE)
-                       return (SET_ERROR(EBADF));
+       nvlist_free(label);
 
-               /*
-                * If we were able to open and validate a vdev that was
-                * previously marked permanently unavailable, clear that state
-                * now.
-                */
-               if (vd->vdev_not_present)
-                       vd->vdev_not_present = 0;
+       /*
+        * If this is a verbatim import, no need to check the
+        * state of the pool.
+        */
+       if (!(spa->spa_import_flags & ZFS_IMPORT_VERBATIM) &&
+           spa_load_state(spa) == SPA_LOAD_OPEN &&
+           state != POOL_STATE_ACTIVE) {
+               vdev_dbgmsg(vd, "vdev_validate: invalid pool state (%llu) "
+                   "for spa %s", (u_longlong_t)state, spa->spa_name);
+               return (SET_ERROR(EBADF));
        }
 
+       /*
+        * If we were able to open and validate a vdev that was
+        * previously marked permanently unavailable, clear that state
+        * now.
+        */
+       if (vd->vdev_not_present)
+               vd->vdev_not_present = 0;
+
        return (0);
 }
 
+static void
+vdev_copy_path_impl(vdev_t *svd, vdev_t *dvd)
+{
+       if (svd->vdev_path != NULL && dvd->vdev_path != NULL) {
+               if (strcmp(svd->vdev_path, dvd->vdev_path) != 0) {
+                       zfs_dbgmsg("vdev_copy_path: vdev %llu: path changed "
+                           "from '%s' to '%s'", (u_longlong_t)dvd->vdev_guid,
+                           dvd->vdev_path, svd->vdev_path);
+                       spa_strfree(dvd->vdev_path);
+                       dvd->vdev_path = spa_strdup(svd->vdev_path);
+               }
+       } else if (svd->vdev_path != NULL) {
+               dvd->vdev_path = spa_strdup(svd->vdev_path);
+               zfs_dbgmsg("vdev_copy_path: vdev %llu: path set to '%s'",
+                   (u_longlong_t)dvd->vdev_guid, dvd->vdev_path);
+       }
+}
+
+/*
+ * Recursively copy vdev paths from one vdev to another. Source and destination
+ * vdev trees must have same geometry otherwise return error. Intended to copy
+ * paths from userland config into MOS config.
+ */
+int
+vdev_copy_path_strict(vdev_t *svd, vdev_t *dvd)
+{
+       if ((svd->vdev_ops == &vdev_missing_ops) ||
+           (svd->vdev_ishole && dvd->vdev_ishole) ||
+           (dvd->vdev_ops == &vdev_indirect_ops))
+               return (0);
+
+       if (svd->vdev_ops != dvd->vdev_ops) {
+               vdev_dbgmsg(svd, "vdev_copy_path: vdev type mismatch: %s != %s",
+                   svd->vdev_ops->vdev_op_type, dvd->vdev_ops->vdev_op_type);
+               return (SET_ERROR(EINVAL));
+       }
+
+       if (svd->vdev_guid != dvd->vdev_guid) {
+               vdev_dbgmsg(svd, "vdev_copy_path: guids mismatch (%llu != "
+                   "%llu)", (u_longlong_t)svd->vdev_guid,
+                   (u_longlong_t)dvd->vdev_guid);
+               return (SET_ERROR(EINVAL));
+       }
+
+       if (svd->vdev_children != dvd->vdev_children) {
+               vdev_dbgmsg(svd, "vdev_copy_path: children count mismatch: "
+                   "%llu != %llu", (u_longlong_t)svd->vdev_children,
+                   (u_longlong_t)dvd->vdev_children);
+               return (SET_ERROR(EINVAL));
+       }
+
+       for (uint64_t i = 0; i < svd->vdev_children; i++) {
+               int error = vdev_copy_path_strict(svd->vdev_child[i],
+                   dvd->vdev_child[i]);
+               if (error != 0)
+                       return (error);
+       }
+
+       if (svd->vdev_ops->vdev_op_leaf)
+               vdev_copy_path_impl(svd, dvd);
+
+       return (0);
+}
+
+static void
+vdev_copy_path_search(vdev_t *stvd, vdev_t *dvd)
+{
+       ASSERT(stvd->vdev_top == stvd);
+       ASSERT3U(stvd->vdev_id, ==, dvd->vdev_top->vdev_id);
+
+       for (uint64_t i = 0; i < dvd->vdev_children; i++) {
+               vdev_copy_path_search(stvd, dvd->vdev_child[i]);
+       }
+
+       if (!dvd->vdev_ops->vdev_op_leaf || !vdev_is_concrete(dvd))
+               return;
+
+       /*
+        * The idea here is that while a vdev can shift positions within
+        * a top vdev (when replacing, attaching mirror, etc.) it cannot
+        * step outside of it.
+        */
+       vdev_t *vd = vdev_lookup_by_guid(stvd, dvd->vdev_guid);
+
+       if (vd == NULL || vd->vdev_ops != dvd->vdev_ops)
+               return;
+
+       ASSERT(vd->vdev_ops->vdev_op_leaf);
+
+       vdev_copy_path_impl(vd, dvd);
+}
+
+/*
+ * Recursively copy vdev paths from one root vdev to another. Source and
+ * destination vdev trees may differ in geometry. For each destination leaf
+ * vdev, search a vdev with the same guid and top vdev id in the source.
+ * Intended to copy paths from userland config into MOS config.
+ */
+void
+vdev_copy_path_relaxed(vdev_t *srvd, vdev_t *drvd)
+{
+       uint64_t children = MIN(srvd->vdev_children, drvd->vdev_children);
+       ASSERT(srvd->vdev_ops == &vdev_root_ops);
+       ASSERT(drvd->vdev_ops == &vdev_root_ops);
+
+       for (uint64_t i = 0; i < children; i++) {
+               vdev_copy_path_search(srvd->vdev_child[i],
+                   drvd->vdev_child[i]);
+       }
+}
+
 /*
  * Close a virtual device.
  */
@@ -1573,13 +2185,12 @@ void
 vdev_hold(vdev_t *vd)
 {
        spa_t *spa = vd->vdev_spa;
-       int c;
 
        ASSERT(spa_is_root(spa));
        if (spa->spa_state == POOL_STATE_UNINITIALIZED)
                return;
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_hold(vd->vdev_child[c]);
 
        if (vd->vdev_ops->vdev_op_leaf)
@@ -1589,10 +2200,8 @@ vdev_hold(vdev_t *vd)
 void
 vdev_rele(vdev_t *vd)
 {
-       int c;
-
        ASSERT(spa_is_root(vd->vdev_spa));
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_rele(vd->vdev_child[c]);
 
        if (vd->vdev_ops->vdev_op_leaf)
@@ -1629,7 +2238,7 @@ vdev_reopen(vdev_t *vd)
                    !l2arc_vdev_present(vd))
                        l2arc_add_vdev(spa, vd);
        } else {
-               (void) vdev_validate(vd, B_TRUE);
+               (void) vdev_validate(vd);
        }
 
        /*
@@ -1671,18 +2280,80 @@ vdev_create(vdev_t *vd, uint64_t txg, boolean_t isreplacing)
 void
 vdev_metaslab_set_size(vdev_t *vd)
 {
+       uint64_t asize = vd->vdev_asize;
+       uint64_t ms_count = asize >> zfs_vdev_default_ms_shift;
+       uint64_t ms_shift;
+
        /*
-        * Aim for roughly metaslabs_per_vdev (default 200) metaslabs per vdev.
+        * There are two dimensions to the metaslab sizing calculation:
+        * the size of the metaslab and the count of metaslabs per vdev.
+        *
+        * The default values used below are a good balance between memory
+        * usage (larger metaslab size means more memory needed for loaded
+        * metaslabs; more metaslabs means more memory needed for the
+        * metaslab_t structs), metaslab load time (larger metaslabs take
+        * longer to load), and metaslab sync time (more metaslabs means
+        * more time spent syncing all of them).
+        *
+        * In general, we aim for zfs_vdev_default_ms_count (200) metaslabs.
+        * The range of the dimensions are as follows:
+        *
+        *      2^29 <= ms_size  <= 2^34
+        *        16 <= ms_count <= 131,072
+        *
+        * On the lower end of vdev sizes, we aim for metaslabs sizes of
+        * at least 512MB (2^29) to minimize fragmentation effects when
+        * testing with smaller devices.  However, the count constraint
+        * of at least 16 metaslabs will override this minimum size goal.
+        *
+        * On the upper end of vdev sizes, we aim for a maximum metaslab
+        * size of 16GB.  However, we will cap the total count to 2^17
+        * metaslabs to keep our memory footprint in check and let the
+        * metaslab size grow from there if that limit is hit.
+        *
+        * The net effect of applying above constrains is summarized below.
+        *
+        *   vdev size       metaslab count
+        *  --------------|-----------------
+        *      < 8GB        ~16
+        *  8GB   - 100GB   one per 512MB
+        *  100GB - 3TB     ~200
+        *  3TB   - 2PB     one per 16GB
+        *      > 2PB       ~131,072
+        *  --------------------------------
+        *
+        *  Finally, note that all of the above calculate the initial
+        *  number of metaslabs. Expanding a top-level vdev will result
+        *  in additional metaslabs being allocated making it possible
+        *  to exceed the zfs_vdev_ms_count_limit.
         */
-       vd->vdev_ms_shift = highbit64(vd->vdev_asize / metaslabs_per_vdev);
-       vd->vdev_ms_shift = MAX(vd->vdev_ms_shift, SPA_MAXBLOCKSHIFT);
+
+       if (ms_count < zfs_vdev_min_ms_count)
+               ms_shift = highbit64(asize / zfs_vdev_min_ms_count);
+       else if (ms_count > zfs_vdev_default_ms_count)
+               ms_shift = highbit64(asize / zfs_vdev_default_ms_count);
+       else
+               ms_shift = zfs_vdev_default_ms_shift;
+
+       if (ms_shift < SPA_MAXBLOCKSHIFT) {
+               ms_shift = SPA_MAXBLOCKSHIFT;
+       } else if (ms_shift > zfs_vdev_max_ms_shift) {
+               ms_shift = zfs_vdev_max_ms_shift;
+               /* cap the total count to constrain memory footprint */
+               if ((asize >> ms_shift) > zfs_vdev_ms_count_limit)
+                       ms_shift = highbit64(asize / zfs_vdev_ms_count_limit);
+       }
+
+       vd->vdev_ms_shift = ms_shift;
+       ASSERT3U(vd->vdev_ms_shift, >=, SPA_MAXBLOCKSHIFT);
 }
 
 void
 vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
 {
        ASSERT(vd == vd->vdev_top);
-       ASSERT(!vd->vdev_ishole);
+       /* indirect vdevs don't have metaslabs or dtls */
+       ASSERT(vdev_is_concrete(vd) || flags == 0);
        ASSERT(ISP2(flags));
        ASSERT(spa_writeable(vd->vdev_spa));
 
@@ -1698,9 +2369,7 @@ vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
 void
 vdev_dirty_leaves(vdev_t *vd, int flags, uint64_t txg)
 {
-       int c;
-
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_dirty_leaves(vd->vdev_child[c], flags, txg);
 
        if (vd->vdev_ops->vdev_op_leaf)
@@ -1754,10 +2423,10 @@ vdev_dtl_dirty(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
        ASSERT(vd != vd->vdev_spa->spa_root_vdev);
        ASSERT(spa_writeable(vd->vdev_spa));
 
-       mutex_enter(rt->rt_lock);
+       mutex_enter(&vd->vdev_dtl_lock);
        if (!range_tree_contains(rt, txg, size))
                range_tree_add(rt, txg, size);
-       mutex_exit(rt->rt_lock);
+       mutex_exit(&vd->vdev_dtl_lock);
 }
 
 boolean_t
@@ -1769,10 +2438,21 @@ vdev_dtl_contains(vdev_t *vd, vdev_dtl_type_t t, uint64_t txg, uint64_t size)
        ASSERT(t < DTL_TYPES);
        ASSERT(vd != vd->vdev_spa->spa_root_vdev);
 
-       mutex_enter(rt->rt_lock);
-       if (range_tree_space(rt) != 0)
+       /*
+        * While we are loading the pool, the DTLs have not been loaded yet.
+        * Ignore the DTLs and try all devices.  This avoids a recursive
+        * mutex enter on the vdev_dtl_lock, and also makes us try hard
+        * when loading the pool (relying on the checksum to ensure that
+        * we get the right data -- note that we while loading, we are
+        * only reading the MOS, which is always checksummed).
+        */
+       if (vd->vdev_spa->spa_load_state != SPA_LOAD_NONE)
+               return (B_FALSE);
+
+       mutex_enter(&vd->vdev_dtl_lock);
+       if (!range_tree_is_empty(rt))
                dirty = range_tree_contains(rt, txg, size);
-       mutex_exit(rt->rt_lock);
+       mutex_exit(&vd->vdev_dtl_lock);
 
        return (dirty);
 }
@@ -1783,13 +2463,28 @@ vdev_dtl_empty(vdev_t *vd, vdev_dtl_type_t t)
        range_tree_t *rt = vd->vdev_dtl[t];
        boolean_t empty;
 
-       mutex_enter(rt->rt_lock);
-       empty = (range_tree_space(rt) == 0);
-       mutex_exit(rt->rt_lock);
+       mutex_enter(&vd->vdev_dtl_lock);
+       empty = range_tree_is_empty(rt);
+       mutex_exit(&vd->vdev_dtl_lock);
 
        return (empty);
 }
 
+/*
+ * Returns B_TRUE if vdev determines offset needs to be resilvered.
+ */
+boolean_t
+vdev_dtl_need_resilver(vdev_t *vd, uint64_t offset, size_t psize)
+{
+       ASSERT(vd != vd->vdev_spa->spa_root_vdev);
+
+       if (vd->vdev_ops->vdev_op_need_resilver == NULL ||
+           vd->vdev_ops->vdev_op_leaf)
+               return (B_TRUE);
+
+       return (vd->vdev_ops->vdev_op_need_resilver(vd, offset, psize));
+}
+
 /*
  * Returns the lowest txg in the DTL range.
  */
@@ -1839,8 +2534,14 @@ vdev_dtl_should_excise(vdev_t *vd)
        ASSERT0(scn->scn_phys.scn_errors);
        ASSERT0(vd->vdev_children);
 
+       if (vd->vdev_state < VDEV_STATE_DEGRADED)
+               return (B_FALSE);
+
+       if (vd->vdev_resilver_deferred)
+               return (B_FALSE);
+
        if (vd->vdev_resilver_txg == 0 ||
-           range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0)
+           range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]))
                return (B_TRUE);
 
        /*
@@ -1860,22 +2561,23 @@ vdev_dtl_should_excise(vdev_t *vd)
 }
 
 /*
- * Reassess DTLs after a config change or scrub completion.
+ * Reassess DTLs after a config change or scrub completion. If txg == 0 no
+ * write operations will be issued to the pool.
  */
 void
 vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
 {
        spa_t *spa = vd->vdev_spa;
        avl_tree_t reftree;
-       int c, t, minref;
+       int minref;
 
        ASSERT(spa_config_held(spa, SCL_ALL, RW_READER) != 0);
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_dtl_reassess(vd->vdev_child[c], txg,
                    scrub_txg, scrub_done);
 
-       if (vd == spa->spa_root_vdev || vd->vdev_ishole || vd->vdev_aux)
+       if (vd == spa->spa_root_vdev || !vdev_is_concrete(vd) || vd->vdev_aux)
                return;
 
        if (vd->vdev_ops->vdev_op_leaf) {
@@ -1883,6 +2585,12 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
 
                mutex_enter(&vd->vdev_dtl_lock);
 
+               /*
+                * If requested, pretend the scan completed cleanly.
+                */
+               if (zfs_scan_ignore_errors && scn)
+                       scn->scn_phys.scn_errors = 0;
+
                /*
                 * If we've completed a scan cleanly then determine
                 * if this vdev should remove any DTLs. We only want to
@@ -1937,9 +2645,9 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
                 * DTLs then reset its resilvering flag and dirty
                 * the top level so that we persist the change.
                 */
-               if (vd->vdev_resilver_txg != 0 &&
-                   range_tree_space(vd->vdev_dtl[DTL_MISSING]) == 0 &&
-                   range_tree_space(vd->vdev_dtl[DTL_OUTAGE]) == 0) {
+               if (txg != 0 && vd->vdev_resilver_txg != 0 &&
+                   range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]) &&
+                   range_tree_is_empty(vd->vdev_dtl[DTL_OUTAGE])) {
                        vd->vdev_resilver_txg = 0;
                        vdev_config_dirty(vd->vdev_top);
                }
@@ -1952,9 +2660,7 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
        }
 
        mutex_enter(&vd->vdev_dtl_lock);
-       for (t = 0; t < DTL_TYPES; t++) {
-               int c;
-
+       for (int t = 0; t < DTL_TYPES; t++) {
                /* account for child's outage in parent's missing map */
                int s = (t == DTL_MISSING) ? DTL_OUTAGE: t;
                if (t == DTL_SCRUB)
@@ -1966,7 +2672,7 @@ vdev_dtl_reassess(vdev_t *vd, uint64_t txg, uint64_t scrub_txg, int scrub_done)
                else
                        minref = vd->vdev_children;     /* any kind of mirror */
                space_reftree_create(&reftree);
-               for (c = 0; c < vd->vdev_children; c++) {
+               for (int c = 0; c < vd->vdev_children; c++) {
                        vdev_t *cvd = vd->vdev_child[c];
                        mutex_enter(&cvd->vdev_dtl_lock);
                        space_reftree_add_map(&reftree, cvd->vdev_dtl[s], 1);
@@ -1984,13 +2690,12 @@ vdev_dtl_load(vdev_t *vd)
        spa_t *spa = vd->vdev_spa;
        objset_t *mos = spa->spa_meta_objset;
        int error = 0;
-       int c;
 
        if (vd->vdev_ops->vdev_op_leaf && vd->vdev_dtl_object != 0) {
-               ASSERT(!vd->vdev_ishole);
+               ASSERT(vdev_is_concrete(vd));
 
                error = space_map_open(&vd->vdev_dtl_sm, mos,
-                   vd->vdev_dtl_object, 0, -1ULL, 0, &vd->vdev_dtl_lock);
+                   vd->vdev_dtl_object, 0, -1ULL, 0);
                if (error)
                        return (error);
                ASSERT(vd->vdev_dtl_sm != NULL);
@@ -2010,7 +2715,7 @@ vdev_dtl_load(vdev_t *vd)
                return (error);
        }
 
-       for (c = 0; c < vd->vdev_children; c++) {
+       for (int c = 0; c < vd->vdev_children; c++) {
                error = vdev_dtl_load(vd->vdev_child[c]);
                if (error != 0)
                        break;
@@ -2019,6 +2724,30 @@ vdev_dtl_load(vdev_t *vd)
        return (error);
 }
 
+static void
+vdev_zap_allocation_data(vdev_t *vd, dmu_tx_t *tx)
+{
+       spa_t *spa = vd->vdev_spa;
+       objset_t *mos = spa->spa_meta_objset;
+       vdev_alloc_bias_t alloc_bias = vd->vdev_alloc_bias;
+       const char *string;
+
+       ASSERT(alloc_bias != VDEV_BIAS_NONE);
+
+       string =
+           (alloc_bias == VDEV_BIAS_LOG) ? VDEV_ALLOC_BIAS_LOG :
+           (alloc_bias == VDEV_BIAS_SPECIAL) ? VDEV_ALLOC_BIAS_SPECIAL :
+           (alloc_bias == VDEV_BIAS_DEDUP) ? VDEV_ALLOC_BIAS_DEDUP : NULL;
+
+       ASSERT(string != NULL);
+       VERIFY0(zap_add(mos, vd->vdev_top_zap, VDEV_TOP_ZAP_ALLOCATION_BIAS,
+           1, strlen(string) + 1, string, tx));
+
+       if (alloc_bias == VDEV_BIAS_SPECIAL || alloc_bias == VDEV_BIAS_DEDUP) {
+               spa_activate_allocation_classes(spa, tx);
+       }
+}
+
 void
 vdev_destroy_unlink_zap(vdev_t *vd, uint64_t zapobj, dmu_tx_t *tx)
 {
@@ -2046,8 +2775,6 @@ vdev_create_link_zap(vdev_t *vd, dmu_tx_t *tx)
 void
 vdev_construct_zaps(vdev_t *vd, dmu_tx_t *tx)
 {
-       uint64_t i;
-
        if (vd->vdev_ops != &vdev_hole_ops &&
            vd->vdev_ops != &vdev_missing_ops &&
            vd->vdev_ops != &vdev_root_ops &&
@@ -2057,9 +2784,12 @@ vdev_construct_zaps(vdev_t *vd, dmu_tx_t *tx)
                }
                if (vd == vd->vdev_top && vd->vdev_top_zap == 0) {
                        vd->vdev_top_zap = vdev_create_link_zap(vd, tx);
+                       if (vd->vdev_alloc_bias != VDEV_BIAS_NONE)
+                               vdev_zap_allocation_data(vd, tx);
                }
        }
-       for (i = 0; i < vd->vdev_children; i++) {
+
+       for (uint64_t i = 0; i < vd->vdev_children; i++) {
                vdev_construct_zaps(vd->vdev_child[i], tx);
        }
 }
@@ -2071,11 +2801,10 @@ vdev_dtl_sync(vdev_t *vd, uint64_t txg)
        range_tree_t *rt = vd->vdev_dtl[DTL_MISSING];
        objset_t *mos = spa->spa_meta_objset;
        range_tree_t *rtsync;
-       kmutex_t rtlock;
        dmu_tx_t *tx;
        uint64_t object = space_map_object(vd->vdev_dtl_sm);
 
-       ASSERT(!vd->vdev_ishole);
+       ASSERT(vdev_is_concrete(vd));
        ASSERT(vd->vdev_ops->vdev_op_leaf);
 
        tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
@@ -2105,41 +2834,35 @@ vdev_dtl_sync(vdev_t *vd, uint64_t txg)
        if (vd->vdev_dtl_sm == NULL) {
                uint64_t new_object;
 
-               new_object = space_map_alloc(mos, tx);
+               new_object = space_map_alloc(mos, vdev_dtl_sm_blksz, tx);
                VERIFY3U(new_object, !=, 0);
 
                VERIFY0(space_map_open(&vd->vdev_dtl_sm, mos, new_object,
-                   0, -1ULL, 0, &vd->vdev_dtl_lock));
+                   0, -1ULL, 0));
                ASSERT(vd->vdev_dtl_sm != NULL);
        }
 
-       mutex_init(&rtlock, NULL, MUTEX_DEFAULT, NULL);
-
-       rtsync = range_tree_create(NULL, NULL, &rtlock);
-
-       mutex_enter(&rtlock);
+       rtsync = range_tree_create(NULL, NULL);
 
        mutex_enter(&vd->vdev_dtl_lock);
        range_tree_walk(rt, range_tree_add, rtsync);
        mutex_exit(&vd->vdev_dtl_lock);
 
-       space_map_truncate(vd->vdev_dtl_sm, tx);
-       space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, tx);
+       space_map_truncate(vd->vdev_dtl_sm, vdev_dtl_sm_blksz, tx);
+       space_map_write(vd->vdev_dtl_sm, rtsync, SM_ALLOC, SM_NO_VDEVID, tx);
        range_tree_vacate(rtsync, NULL, NULL);
 
        range_tree_destroy(rtsync);
 
-       mutex_exit(&rtlock);
-       mutex_destroy(&rtlock);
-
        /*
         * If the object for the space map has changed then dirty
         * the top level so that we update the config.
         */
        if (object != space_map_object(vd->vdev_dtl_sm)) {
-               zfs_dbgmsg("txg %llu, spa %s, DTL old object %llu, "
-                   "new object %llu", txg, spa_name(spa), object,
-                   space_map_object(vd->vdev_dtl_sm));
+               vdev_dbgmsg(vd, "txg %llu, spa %s, DTL old object %llu, "
+                   "new object %llu", (u_longlong_t)txg, spa_name(spa),
+                   (u_longlong_t)object,
+                   (u_longlong_t)space_map_object(vd->vdev_dtl_sm));
                vdev_config_dirty(vd->vdev_top);
        }
 
@@ -2193,11 +2916,10 @@ vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
        boolean_t needed = B_FALSE;
        uint64_t thismin = UINT64_MAX;
        uint64_t thismax = 0;
-       int c;
 
        if (vd->vdev_children == 0) {
                mutex_enter(&vd->vdev_dtl_lock);
-               if (range_tree_space(vd->vdev_dtl[DTL_MISSING]) != 0 &&
+               if (!range_tree_is_empty(vd->vdev_dtl[DTL_MISSING]) &&
                    vdev_writeable(vd)) {
 
                        thismin = vdev_dtl_min(vd);
@@ -2206,7 +2928,7 @@ vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
                }
                mutex_exit(&vd->vdev_dtl_lock);
        } else {
-               for (c = 0; c < vd->vdev_children; c++) {
+               for (int c = 0; c < vd->vdev_children; c++) {
                        vdev_t *cvd = vd->vdev_child[c];
                        uint64_t cmin, cmax;
 
@@ -2225,31 +2947,155 @@ vdev_resilver_needed(vdev_t *vd, uint64_t *minp, uint64_t *maxp)
        return (needed);
 }
 
-void
+/*
+ * Gets the checkpoint space map object from the vdev's ZAP.  On success sm_obj
+ * will contain either the checkpoint spacemap object or zero if none exists.
+ * All other errors are returned to the caller.
+ */
+int
+vdev_checkpoint_sm_object(vdev_t *vd, uint64_t *sm_obj)
+{
+       ASSERT0(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
+
+       if (vd->vdev_top_zap == 0) {
+               *sm_obj = 0;
+               return (0);
+       }
+
+       int error = zap_lookup(spa_meta_objset(vd->vdev_spa), vd->vdev_top_zap,
+           VDEV_TOP_ZAP_POOL_CHECKPOINT_SM, sizeof (uint64_t), 1, sm_obj);
+       if (error == ENOENT) {
+               *sm_obj = 0;
+               error = 0;
+       }
+
+       return (error);
+}
+
+int
 vdev_load(vdev_t *vd)
 {
-       int c;
+       int error = 0;
 
        /*
         * Recursively load all children.
         */
-       for (c = 0; c < vd->vdev_children; c++)
-               vdev_load(vd->vdev_child[c]);
+       for (int c = 0; c < vd->vdev_children; c++) {
+               error = vdev_load(vd->vdev_child[c]);
+               if (error != 0) {
+                       return (error);
+               }
+       }
+
+       vdev_set_deflate_ratio(vd);
+
+       /*
+        * On spa_load path, grab the allocation bias from our zap
+        */
+       if (vd == vd->vdev_top && vd->vdev_top_zap != 0) {
+               spa_t *spa = vd->vdev_spa;
+               char bias_str[64];
+
+               if (zap_lookup(spa->spa_meta_objset, vd->vdev_top_zap,
+                   VDEV_TOP_ZAP_ALLOCATION_BIAS, 1, sizeof (bias_str),
+                   bias_str) == 0) {
+                       ASSERT(vd->vdev_alloc_bias == VDEV_BIAS_NONE);
+                       vd->vdev_alloc_bias = vdev_derive_alloc_bias(bias_str);
+               }
+       }
 
        /*
         * If this is a top-level vdev, initialize its metaslabs.
         */
-       if (vd == vd->vdev_top && !vd->vdev_ishole &&
-           (vd->vdev_ashift == 0 || vd->vdev_asize == 0 ||
-           vdev_metaslab_init(vd, 0) != 0))
-               vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
-                   VDEV_AUX_CORRUPT_DATA);
+       if (vd == vd->vdev_top && vdev_is_concrete(vd)) {
+               vdev_metaslab_group_create(vd);
+
+               if (vd->vdev_ashift == 0 || vd->vdev_asize == 0) {
+                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                           VDEV_AUX_CORRUPT_DATA);
+                       vdev_dbgmsg(vd, "vdev_load: invalid size. ashift=%llu, "
+                           "asize=%llu", (u_longlong_t)vd->vdev_ashift,
+                           (u_longlong_t)vd->vdev_asize);
+                       return (SET_ERROR(ENXIO));
+               } else if ((error = vdev_metaslab_init(vd, 0)) != 0) {
+                       vdev_dbgmsg(vd, "vdev_load: metaslab_init failed "
+                           "[error=%d]", error);
+                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                           VDEV_AUX_CORRUPT_DATA);
+                       return (error);
+               }
+
+               uint64_t checkpoint_sm_obj;
+               error = vdev_checkpoint_sm_object(vd, &checkpoint_sm_obj);
+               if (error == 0 && checkpoint_sm_obj != 0) {
+                       objset_t *mos = spa_meta_objset(vd->vdev_spa);
+                       ASSERT(vd->vdev_asize != 0);
+                       ASSERT3P(vd->vdev_checkpoint_sm, ==, NULL);
+
+                       if ((error = space_map_open(&vd->vdev_checkpoint_sm,
+                           mos, checkpoint_sm_obj, 0, vd->vdev_asize,
+                           vd->vdev_ashift))) {
+                               vdev_dbgmsg(vd, "vdev_load: space_map_open "
+                                   "failed for checkpoint spacemap (obj %llu) "
+                                   "[error=%d]",
+                                   (u_longlong_t)checkpoint_sm_obj, error);
+                               return (error);
+                       }
+                       ASSERT3P(vd->vdev_checkpoint_sm, !=, NULL);
+                       space_map_update(vd->vdev_checkpoint_sm);
+
+                       /*
+                        * Since the checkpoint_sm contains free entries
+                        * exclusively we can use sm_alloc to indicate the
+                        * cumulative checkpointed space that has been freed.
+                        */
+                       vd->vdev_stat.vs_checkpoint_space =
+                           -vd->vdev_checkpoint_sm->sm_alloc;
+                       vd->vdev_spa->spa_checkpoint_info.sci_dspace +=
+                           vd->vdev_stat.vs_checkpoint_space;
+               } else if (error != 0) {
+                       vdev_dbgmsg(vd, "vdev_load: failed to retrieve "
+                           "checkpoint space map object from vdev ZAP "
+                           "[error=%d]", error);
+                       return (error);
+               }
+       }
+
        /*
         * If this is a leaf vdev, load its DTL.
         */
-       if (vd->vdev_ops->vdev_op_leaf && vdev_dtl_load(vd) != 0)
+       if (vd->vdev_ops->vdev_op_leaf && (error = vdev_dtl_load(vd)) != 0) {
                vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
                    VDEV_AUX_CORRUPT_DATA);
+               vdev_dbgmsg(vd, "vdev_load: vdev_dtl_load failed "
+                   "[error=%d]", error);
+               return (error);
+       }
+
+       uint64_t obsolete_sm_object;
+       error = vdev_obsolete_sm_object(vd, &obsolete_sm_object);
+       if (error == 0 && obsolete_sm_object != 0) {
+               objset_t *mos = vd->vdev_spa->spa_meta_objset;
+               ASSERT(vd->vdev_asize != 0);
+               ASSERT3P(vd->vdev_obsolete_sm, ==, NULL);
+
+               if ((error = space_map_open(&vd->vdev_obsolete_sm, mos,
+                   obsolete_sm_object, 0, vd->vdev_asize, 0))) {
+                       vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
+                           VDEV_AUX_CORRUPT_DATA);
+                       vdev_dbgmsg(vd, "vdev_load: space_map_open failed for "
+                           "obsolete spacemap (obj %llu) [error=%d]",
+                           (u_longlong_t)obsolete_sm_object, error);
+                       return (error);
+               }
+               space_map_update(vd->vdev_obsolete_sm);
+       } else if (error != 0) {
+               vdev_dbgmsg(vd, "vdev_load: failed to retrieve obsolete "
+                   "space map object from vdev ZAP [error=%d]", error);
+               return (error);
+       }
+
+       return (0);
 }
 
 /*
@@ -2294,15 +3140,42 @@ vdev_validate_aux(vdev_t *vd)
        return (0);
 }
 
+/*
+ * Free the objects used to store this vdev's spacemaps, and the array
+ * that points to them.
+ */
 void
-vdev_remove(vdev_t *vd, uint64_t txg)
+vdev_destroy_spacemaps(vdev_t *vd, dmu_tx_t *tx)
+{
+       if (vd->vdev_ms_array == 0)
+               return;
+
+       objset_t *mos = vd->vdev_spa->spa_meta_objset;
+       uint64_t array_count = vd->vdev_asize >> vd->vdev_ms_shift;
+       size_t array_bytes = array_count * sizeof (uint64_t);
+       uint64_t *smobj_array = kmem_alloc(array_bytes, KM_SLEEP);
+       VERIFY0(dmu_read(mos, vd->vdev_ms_array, 0,
+           array_bytes, smobj_array, 0));
+
+       for (uint64_t i = 0; i < array_count; i++) {
+               uint64_t smobj = smobj_array[i];
+               if (smobj == 0)
+                       continue;
+
+               space_map_free_obj(mos, smobj, tx);
+       }
+
+       kmem_free(smobj_array, array_bytes);
+       VERIFY0(dmu_object_free(mos, vd->vdev_ms_array, tx));
+       vd->vdev_ms_array = 0;
+}
+
+static void
+vdev_remove_empty_log(vdev_t *vd, uint64_t txg)
 {
        spa_t *spa = vd->vdev_spa;
-       objset_t *mos = spa->spa_meta_objset;
-       dmu_tx_t *tx;
-       int m, i;
 
-       tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
+       ASSERT(vd->vdev_islog);
        ASSERT(vd == vd->vdev_top);
        ASSERT3U(txg, ==, spa_syncing_txg(spa));
 
@@ -2312,7 +3185,7 @@ vdev_remove(vdev_t *vd, uint64_t txg)
                metaslab_group_histogram_verify(mg);
                metaslab_class_histogram_verify(mg->mg_class);
 
-               for (m = 0; m < vd->vdev_ms_count; m++) {
+               for (int m = 0; m < vd->vdev_ms_count; m++) {
                        metaslab_t *msp = vd->vdev_ms[m];
 
                        if (msp == NULL || msp->ms_sm == NULL)
@@ -2329,28 +3202,32 @@ vdev_remove(vdev_t *vd, uint64_t txg)
                        metaslab_group_histogram_remove(mg, msp);
 
                        VERIFY0(space_map_allocated(msp->ms_sm));
-                       space_map_free(msp->ms_sm, tx);
                        space_map_close(msp->ms_sm);
                        msp->ms_sm = NULL;
                        mutex_exit(&msp->ms_lock);
                }
 
+               if (vd->vdev_checkpoint_sm != NULL) {
+                       ASSERT(spa_has_checkpoint(spa));
+                       space_map_close(vd->vdev_checkpoint_sm);
+                       vd->vdev_checkpoint_sm = NULL;
+               }
+
                metaslab_group_histogram_verify(mg);
                metaslab_class_histogram_verify(mg->mg_class);
-               for (i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
-                       ASSERT0(mg->mg_histogram[i]);
 
+               for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++)
+                       ASSERT0(mg->mg_histogram[i]);
        }
 
-       if (vd->vdev_ms_array) {
-               (void) dmu_object_free(mos, vd->vdev_ms_array, tx);
-               vd->vdev_ms_array = 0;
-       }
+       dmu_tx_t *tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
 
-       if (vd->vdev_islog && vd->vdev_top_zap != 0) {
+       vdev_destroy_spacemaps(vd, tx);
+       if (vd->vdev_top_zap != 0) {
                vdev_destroy_unlink_zap(vd, vd->vdev_top_zap, tx);
                vd->vdev_top_zap = 0;
        }
+
        dmu_tx_commit(tx);
 }
 
@@ -2360,9 +3237,10 @@ vdev_sync_done(vdev_t *vd, uint64_t txg)
        metaslab_t *msp;
        boolean_t reassess = !txg_list_empty(&vd->vdev_ms_list, TXG_CLEAN(txg));
 
-       ASSERT(!vd->vdev_ishole);
+       ASSERT(vdev_is_concrete(vd));
 
-       while ((msp = txg_list_remove(&vd->vdev_ms_list, TXG_CLEAN(txg))))
+       while ((msp = txg_list_remove(&vd->vdev_ms_list, TXG_CLEAN(txg)))
+           != NULL)
                metaslab_sync_done(msp, txg);
 
        if (reassess)
@@ -2377,10 +3255,33 @@ vdev_sync(vdev_t *vd, uint64_t txg)
        metaslab_t *msp;
        dmu_tx_t *tx;
 
-       ASSERT(!vd->vdev_ishole);
+       if (range_tree_space(vd->vdev_obsolete_segments) > 0) {
+               dmu_tx_t *tx;
+
+               ASSERT(vd->vdev_removing ||
+                   vd->vdev_ops == &vdev_indirect_ops);
+
+               tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
+               vdev_indirect_sync_obsolete(vd, tx);
+               dmu_tx_commit(tx);
+
+               /*
+                * If the vdev is indirect, it can't have dirty
+                * metaslabs or DTLs.
+                */
+               if (vd->vdev_ops == &vdev_indirect_ops) {
+                       ASSERT(txg_list_empty(&vd->vdev_ms_list, txg));
+                       ASSERT(txg_list_empty(&vd->vdev_dtl_list, txg));
+                       return;
+               }
+       }
+
+       ASSERT(vdev_is_concrete(vd));
 
-       if (vd->vdev_ms_array == 0 && vd->vdev_ms_shift != 0) {
+       if (vd->vdev_ms_array == 0 && vd->vdev_ms_shift != 0 &&
+           !vd->vdev_removing) {
                ASSERT(vd == vd->vdev_top);
+               ASSERT0(vd->vdev_indirect_config.vic_mapping_object);
                tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
                vd->vdev_ms_array = dmu_object_alloc(spa->spa_meta_objset,
                    DMU_OT_OBJECT_ARRAY, 0, DMU_OT_NONE, 0, tx);
@@ -2389,12 +3290,6 @@ vdev_sync(vdev_t *vd, uint64_t txg)
                dmu_tx_commit(tx);
        }
 
-       /*
-        * Remove the metadata associated with this vdev once it's empty.
-        */
-       if (vd->vdev_stat.vs_alloc == 0 && vd->vdev_removing)
-               vdev_remove(vd, txg);
-
        while ((msp = txg_list_remove(&vd->vdev_ms_list, txg)) != NULL) {
                metaslab_sync(msp, txg);
                (void) txg_list_add(&vd->vdev_ms_list, msp, TXG_CLEAN(txg));
@@ -2403,6 +3298,13 @@ vdev_sync(vdev_t *vd, uint64_t txg)
        while ((lvd = txg_list_remove(&vd->vdev_dtl_list, txg)) != NULL)
                vdev_dtl_sync(lvd, txg);
 
+       /*
+        * If this is an empty log device being removed, destroy the
+        * metadata associated with it.
+        */
+       if (vd->vdev_islog && vd->vdev_stat.vs_alloc == 0 && vd->vdev_removing)
+               vdev_remove_empty_log(vd, txg);
+
        (void) txg_list_add(&spa->spa_vdev_txg_list, vd, TXG_CLEAN(txg));
 }
 
@@ -2431,6 +3333,32 @@ vdev_fault(spa_t *spa, uint64_t guid, vdev_aux_t aux)
 
        tvd = vd->vdev_top;
 
+       /*
+        * If user did a 'zpool offline -f' then make the fault persist across
+        * reboots.
+        */
+       if (aux == VDEV_AUX_EXTERNAL_PERSIST) {
+               /*
+                * There are two kinds of forced faults: temporary and
+                * persistent.  Temporary faults go away at pool import, while
+                * persistent faults stay set.  Both types of faults can be
+                * cleared with a zpool clear.
+                *
+                * We tell if a vdev is persistently faulted by looking at the
+                * ZPOOL_CONFIG_AUX_STATE nvpair.  If it's set to "external" at
+                * import then it's a persistent fault.  Otherwise, it's
+                * temporary.  We get ZPOOL_CONFIG_AUX_STATE set to "external"
+                * by setting vd.vdev_stat.vs_aux to VDEV_AUX_EXTERNAL.  This
+                * tells vdev_config_generate() (which gets run later) to set
+                * ZPOOL_CONFIG_AUX_STATE to "external" in the nvlist.
+                */
+               vd->vdev_stat.vs_aux = VDEV_AUX_EXTERNAL;
+               vd->vdev_tmpoffline = B_FALSE;
+               aux = VDEV_AUX_EXTERNAL;
+       } else {
+               vd->vdev_tmpoffline = B_TRUE;
+       }
+
        /*
         * We don't directly use the aux state here, but if we do a
         * vdev_reopen(), we need this value to be present to remember why we
@@ -2511,7 +3439,8 @@ int
 vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
 {
        vdev_t *vd, *tvd, *pvd, *rvd = spa->spa_root_vdev;
-       boolean_t postevent = B_FALSE;
+       boolean_t wasoffline;
+       vdev_state_t oldstate;
 
        spa_vdev_state_enter(spa, SCL_NONE);
 
@@ -2521,9 +3450,8 @@ vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
        if (!vd->vdev_ops->vdev_op_leaf)
                return (spa_vdev_state_exit(spa, NULL, ENOTSUP));
 
-       postevent =
-           (vd->vdev_offline == B_TRUE || vd->vdev_tmpoffline == B_TRUE) ?
-           B_TRUE : B_FALSE;
+       wasoffline = (vd->vdev_offline || vd->vdev_tmpoffline);
+       oldstate = vd->vdev_state;
 
        tvd = vd->vdev_top;
        vd->vdev_offline = B_FALSE;
@@ -2534,7 +3462,9 @@ vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
        /* XXX - L2ARC 1.0 does not support expansion */
        if (!vd->vdev_aux) {
                for (pvd = vd; pvd != rvd; pvd = pvd->vdev_parent)
-                       pvd->vdev_expanding = !!(flags & ZFS_ONLINE_EXPAND);
+                       pvd->vdev_expanding = !!((flags & ZFS_ONLINE_EXPAND) ||
+                           spa->spa_autoexpand);
+               vd->vdev_expansion_time = gethrestime_sec();
        }
 
        vdev_reopen(tvd);
@@ -2561,8 +3491,19 @@ vdev_online(spa_t *spa, uint64_t guid, uint64_t flags, vdev_state_t *newstate)
                spa_async_request(spa, SPA_ASYNC_CONFIG_UPDATE);
        }
 
-       if (postevent)
-               spa_event_notify(spa, vd, ESC_ZFS_VDEV_ONLINE);
+       /* Restart initializing if necessary */
+       mutex_enter(&vd->vdev_initialize_lock);
+       if (vdev_writeable(vd) &&
+           vd->vdev_initialize_thread == NULL &&
+           vd->vdev_initialize_state == VDEV_INITIALIZE_ACTIVE) {
+               (void) vdev_initialize(vd);
+       }
+       mutex_exit(&vd->vdev_initialize_lock);
+
+       if (wasoffline ||
+           (oldstate < VDEV_STATE_DEGRADED &&
+           vd->vdev_state >= VDEV_STATE_DEGRADED))
+               spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_ONLINE);
 
        return (spa_vdev_state_exit(spa, vd, 0));
 }
@@ -2614,7 +3555,18 @@ top:
                        metaslab_group_passivate(mg);
                        (void) spa_vdev_state_exit(spa, vd, 0);
 
-                       error = spa_offline_log(spa);
+                       error = spa_reset_logs(spa);
+
+                       /*
+                        * If the log device was successfully reset but has
+                        * checkpointed data, do not offline it.
+                        */
+                       if (error == 0 &&
+                           tvd->vdev_checkpoint_sm != NULL) {
+                               ASSERT3U(tvd->vdev_checkpoint_sm->sm_alloc,
+                                   !=, 0);
+                               error = ZFS_ERR_CHECKPOINT_EXISTS;
+                       }
 
                        spa_vdev_state_enter(spa, SCL_ALLOC);
 
@@ -2682,7 +3634,6 @@ void
 vdev_clear(spa_t *spa, vdev_t *vd)
 {
        vdev_t *rvd = spa->spa_root_vdev;
-       int c;
 
        ASSERT(spa_config_held(spa, SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
 
@@ -2692,10 +3643,17 @@ vdev_clear(spa_t *spa, vdev_t *vd)
        vd->vdev_stat.vs_read_errors = 0;
        vd->vdev_stat.vs_write_errors = 0;
        vd->vdev_stat.vs_checksum_errors = 0;
+       vd->vdev_stat.vs_slow_ios = 0;
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_clear(spa, vd->vdev_child[c]);
 
+       /*
+        * It makes no sense to "clear" an indirect vdev.
+        */
+       if (!vdev_is_concrete(vd))
+               return;
+
        /*
         * If we're in the FAULTED state or have experienced failed I/O, then
         * clear the persistent state and attempt to reopen the device.  We
@@ -2704,7 +3662,6 @@ vdev_clear(spa_t *spa, vdev_t *vd)
         */
        if (vd->vdev_faulted || vd->vdev_degraded ||
            !vdev_readable(vd) || !vdev_writeable(vd)) {
-
                /*
                 * When reopening in response to a clear event, it may be due to
                 * a fmadm repair request.  In this case, if the device is
@@ -2715,6 +3672,7 @@ vdev_clear(spa_t *spa, vdev_t *vd)
                vd->vdev_faulted = vd->vdev_degraded = 0ULL;
                vd->vdev_cant_read = B_FALSE;
                vd->vdev_cant_write = B_FALSE;
+               vd->vdev_stat.vs_aux = 0;
 
                vdev_reopen(vd == rvd ? rvd : vd->vdev_top);
 
@@ -2723,10 +3681,16 @@ vdev_clear(spa_t *spa, vdev_t *vd)
                if (vd != rvd && vdev_writeable(vd->vdev_top))
                        vdev_state_dirty(vd->vdev_top);
 
-               if (vd->vdev_aux == NULL && !vdev_is_dead(vd))
-                       spa_async_request(spa, SPA_ASYNC_RESILVER);
+               if (vd->vdev_aux == NULL && !vdev_is_dead(vd)) {
+                       if (dsl_scan_resilvering(spa->spa_dsl_pool) &&
+                           spa_feature_is_enabled(spa,
+                           SPA_FEATURE_RESILVER_DEFER))
+                               vdev_set_deferred_resilver(spa, vd);
+                       else
+                               spa_async_request(spa, SPA_ASYNC_RESILVER);
+               }
 
-               spa_event_notify(spa, vd, ESC_ZFS_VDEV_CLEAR);
+               spa_event_notify(spa, vd, NULL, ESC_ZFS_VDEV_CLEAR);
        }
 
        /*
@@ -2750,7 +3714,8 @@ vdev_is_dead(vdev_t *vd)
         * Instead we rely on the fact that we skip over dead devices
         * before issuing I/O to them.
         */
-       return (vd->vdev_state < VDEV_STATE_DEGRADED || vd->vdev_ishole ||
+       return (vd->vdev_state < VDEV_STATE_DEGRADED ||
+           vd->vdev_ops == &vdev_hole_ops ||
            vd->vdev_ops == &vdev_missing_ops);
 }
 
@@ -2763,7 +3728,8 @@ vdev_readable(vdev_t *vd)
 boolean_t
 vdev_writeable(vdev_t *vd)
 {
-       return (!vdev_is_dead(vd) && !vd->vdev_cant_write);
+       return (!vdev_is_dead(vd) && !vd->vdev_cant_write &&
+           vdev_is_concrete(vd));
 }
 
 boolean_t
@@ -2780,7 +3746,7 @@ vdev_allocatable(vdev_t *vd)
         * we're asking two separate questions about it.
         */
        return (!(state < VDEV_STATE_DEGRADED && state != VDEV_STATE_CLOSED) &&
-           !vd->vdev_cant_write && !vd->vdev_ishole &&
+           !vd->vdev_cant_write && vdev_is_concrete(vd) &&
            vd->vdev_mg->mg_initialized);
 }
 
@@ -2847,13 +3813,34 @@ vdev_get_child_stat_ex(vdev_t *cvd, vdev_stat_ex_t *vsx, vdev_stat_ex_t *cvsx)
 
 }
 
+boolean_t
+vdev_is_spacemap_addressable(vdev_t *vd)
+{
+       if (spa_feature_is_active(vd->vdev_spa, SPA_FEATURE_SPACEMAP_V2))
+               return (B_TRUE);
+
+       /*
+        * If double-word space map entries are not enabled we assume
+        * 47 bits of the space map entry are dedicated to the entry's
+        * offset (see SM_OFFSET_BITS in space_map.h). We then use that
+        * to calculate the maximum address that can be described by a
+        * space map entry for the given device.
+        */
+       uint64_t shift = vd->vdev_ashift + SM_OFFSET_BITS;
+
+       if (shift >= 63) /* detect potential overflow */
+               return (B_TRUE);
+
+       return (vd->vdev_asize < (1ULL << shift));
+}
+
 /*
  * Get statistics for the given vdev.
  */
 static void
 vdev_get_stats_ex_impl(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
 {
-       int c, t;
+       int t;
        /*
         * If we're getting stats on the root vdev, aggregate the I/O counts
         * over all top-level vdevs (i.e. the direct children of the root).
@@ -2866,7 +3853,7 @@ vdev_get_stats_ex_impl(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
                if (vsx)
                        memset(vsx, 0, sizeof (*vsx));
 
-               for (c = 0; c < vd->vdev_children; c++) {
+               for (int c = 0; c < vd->vdev_children; c++) {
                        vdev_t *cvd = vd->vdev_child[c];
                        vdev_stat_t *cvs = &cvd->vdev_stat;
                        vdev_stat_ex_t *cvsx = &cvd->vdev_stat_ex;
@@ -2907,9 +3894,22 @@ vdev_get_stats_ex(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
                vs->vs_timestamp = gethrtime() - vs->vs_timestamp;
                vs->vs_state = vd->vdev_state;
                vs->vs_rsize = vdev_get_min_asize(vd);
-               if (vd->vdev_ops->vdev_op_leaf)
+               if (vd->vdev_ops->vdev_op_leaf) {
                        vs->vs_rsize += VDEV_LABEL_START_SIZE +
                            VDEV_LABEL_END_SIZE;
+                       /*
+                        * Report intializing progress. Since we don't
+                        * have the initializing locks held, this is only
+                        * an estimate (although a fairly accurate one).
+                        */
+                       vs->vs_initialize_bytes_done =
+                           vd->vdev_initialize_bytes_done;
+                       vs->vs_initialize_bytes_est =
+                           vd->vdev_initialize_bytes_est;
+                       vs->vs_initialize_state = vd->vdev_initialize_state;
+                       vs->vs_initialize_action_time =
+                           vd->vdev_initialize_action_time;
+               }
                /*
                 * Report expandable space on top-level, non-auxillary devices
                 * only. The expandable space is reported in terms of metaslab
@@ -2921,11 +3921,13 @@ vdev_get_stats_ex(vdev_t *vd, vdev_stat_t *vs, vdev_stat_ex_t *vsx)
                            vd->vdev_max_asize - vd->vdev_asize,
                            1ULL << tvd->vdev_ms_shift);
                }
-               vs->vs_esize = vd->vdev_max_asize - vd->vdev_asize;
                if (vd->vdev_aux == NULL && vd == vd->vdev_top &&
-                   !vd->vdev_ishole) {
-                       vs->vs_fragmentation = vd->vdev_mg->mg_fragmentation;
+                   vdev_is_concrete(vd)) {
+                       vs->vs_fragmentation = (vd->vdev_mg != NULL) ?
+                           vd->vdev_mg->mg_fragmentation : 0;
                }
+               if (vd->vdev_ops->vdev_op_leaf)
+                       vs->vs_resilver_deferred = vd->vdev_resilver_deferred;
        }
 
        ASSERT(spa_config_held(vd->vdev_spa, SCL_ALL, RW_READER) != 0);
@@ -2953,9 +3955,8 @@ void
 vdev_scan_stat_init(vdev_t *vd)
 {
        vdev_stat_t *vs = &vd->vdev_stat;
-       int c;
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                vdev_scan_stat_init(vd->vdev_child[c]);
 
        mutex_enter(&vd->vdev_stat_lock);
@@ -3087,7 +4088,8 @@ vdev_stat_update(zio_t *zio, uint64_t psize)
                vs->vs_write_errors++;
        mutex_exit(&vd->vdev_stat_lock);
 
-       if (type == ZIO_TYPE_WRITE && txg != 0 &&
+       if (spa->spa_load_state == SPA_LOAD_NONE &&
+           type == ZIO_TYPE_WRITE && txg != 0 &&
            (!(flags & ZIO_FLAG_IO_REPAIR) ||
            (flags & ZIO_FLAG_SCAN_THREAD) ||
            spa->spa_claiming)) {
@@ -3129,19 +4131,25 @@ vdev_stat_update(zio_t *zio, uint64_t psize)
        }
 }
 
+int64_t
+vdev_deflated_space(vdev_t *vd, int64_t space)
+{
+       ASSERT((space & (SPA_MINBLOCKSIZE-1)) == 0);
+       ASSERT(vd->vdev_deflate_ratio != 0 || vd->vdev_isl2cache);
+
+       return ((space >> SPA_MINBLOCKSHIFT) * vd->vdev_deflate_ratio);
+}
+
 /*
- * Update the in-core space usage stats for this vdev, its metaslab class,
- * and the root vdev.
+ * Update the in-core space usage stats for this vdev and the root vdev.
  */
 void
 vdev_space_update(vdev_t *vd, int64_t alloc_delta, int64_t defer_delta,
     int64_t space_delta)
 {
-       int64_t dspace_delta = space_delta;
+       int64_t dspace_delta;
        spa_t *spa = vd->vdev_spa;
        vdev_t *rvd = spa->spa_root_vdev;
-       metaslab_group_t *mg = vd->vdev_mg;
-       metaslab_class_t *mc = mg ? mg->mg_class : NULL;
 
        ASSERT(vd == vd->vdev_top);
 
@@ -3151,32 +4159,29 @@ vdev_space_update(vdev_t *vd, int64_t alloc_delta, int64_t defer_delta,
         * because the root vdev's psize-to-asize is simply the max of its
         * childrens', thus not accurate enough for us.
         */
-       ASSERT((dspace_delta & (SPA_MINBLOCKSIZE-1)) == 0);
-       ASSERT(vd->vdev_deflate_ratio != 0 || vd->vdev_isl2cache);
-       dspace_delta = (dspace_delta >> SPA_MINBLOCKSHIFT) *
-           vd->vdev_deflate_ratio;
+       dspace_delta = vdev_deflated_space(vd, space_delta);
 
        mutex_enter(&vd->vdev_stat_lock);
+       /* ensure we won't underflow */
+       if (alloc_delta < 0) {
+               ASSERT3U(vd->vdev_stat.vs_alloc, >=, -alloc_delta);
+       }
+
        vd->vdev_stat.vs_alloc += alloc_delta;
        vd->vdev_stat.vs_space += space_delta;
        vd->vdev_stat.vs_dspace += dspace_delta;
        mutex_exit(&vd->vdev_stat_lock);
 
-       if (mc == spa_normal_class(spa)) {
+       /* every class but log contributes to root space stats */
+       if (vd->vdev_mg != NULL && !vd->vdev_islog) {
+               ASSERT(!vd->vdev_isl2cache);
                mutex_enter(&rvd->vdev_stat_lock);
                rvd->vdev_stat.vs_alloc += alloc_delta;
                rvd->vdev_stat.vs_space += space_delta;
                rvd->vdev_stat.vs_dspace += dspace_delta;
                mutex_exit(&rvd->vdev_stat_lock);
        }
-
-       if (mc != NULL) {
-               ASSERT(rvd == vd->vdev_parent);
-               ASSERT(vd->vdev_ms_count != 0);
-
-               metaslab_class_space_update(mc,
-                   alloc_delta, defer_delta, space_delta, dspace_delta);
-       }
+       /* Note: metaslab_class_space_update moved to metaslab_space_update */
 }
 
 /*
@@ -3252,8 +4257,9 @@ vdev_config_dirty(vdev_t *vd)
                ASSERT(vd == vd->vdev_top);
 
                if (!list_link_active(&vd->vdev_config_dirty_node) &&
-                   !vd->vdev_ishole)
+                   vdev_is_concrete(vd)) {
                        list_insert_head(&spa->spa_config_dirty_list, vd);
+               }
        }
 }
 
@@ -3294,7 +4300,8 @@ vdev_state_dirty(vdev_t *vd)
            (dsl_pool_sync_context(spa_get_dsl(spa)) &&
            spa_config_held(spa, SCL_STATE, RW_READER)));
 
-       if (!list_link_active(&vd->vdev_state_dirty_node) && !vd->vdev_ishole)
+       if (!list_link_active(&vd->vdev_state_dirty_node) &&
+           vdev_is_concrete(vd))
                list_insert_head(&spa->spa_state_dirty_list, vd);
 }
 
@@ -3322,16 +4329,16 @@ vdev_propagate_state(vdev_t *vd)
        int degraded = 0, faulted = 0;
        int corrupted = 0;
        vdev_t *child;
-       int c;
 
        if (vd->vdev_children > 0) {
-               for (c = 0; c < vd->vdev_children; c++) {
+               for (int c = 0; c < vd->vdev_children; c++) {
                        child = vd->vdev_child[c];
 
                        /*
-                        * Don't factor holes into the decision.
+                        * Don't factor holes or indirect vdevs into the
+                        * decision.
                         */
-                       if (child->vdev_ishole)
+                       if (!vdev_is_concrete(child))
                                continue;
 
                        if (!vdev_readable(child) ||
@@ -3487,11 +4494,15 @@ vdev_set_state(vdev_t *vd, boolean_t isopen, vdev_state_t state, vdev_aux_t aux)
                        case VDEV_AUX_BAD_LABEL:
                                class = FM_EREPORT_ZFS_DEVICE_BAD_LABEL;
                                break;
+                       case VDEV_AUX_BAD_ASHIFT:
+                               class = FM_EREPORT_ZFS_DEVICE_BAD_ASHIFT;
+                               break;
                        default:
                                class = FM_EREPORT_ZFS_DEVICE_UNKNOWN;
                        }
 
-                       zfs_ereport_post(class, spa, vd, NULL, save_state, 0);
+                       zfs_ereport_post(class, spa, vd, NULL, NULL,
+                           save_state, 0);
                }
 
                /* Erase any notion of persistent removed state */
@@ -3520,68 +4531,51 @@ vdev_set_state(vdev_t *vd, boolean_t isopen, vdev_state_t state, vdev_aux_t aux)
                vdev_propagate_state(vd->vdev_parent);
 }
 
+boolean_t
+vdev_children_are_offline(vdev_t *vd)
+{
+       ASSERT(!vd->vdev_ops->vdev_op_leaf);
+
+       for (uint64_t i = 0; i < vd->vdev_children; i++) {
+               if (vd->vdev_child[i]->vdev_state != VDEV_STATE_OFFLINE)
+                       return (B_FALSE);
+       }
+
+       return (B_TRUE);
+}
+
 /*
  * Check the vdev configuration to ensure that it's capable of supporting
- * a root pool.
+ * a root pool. We do not support partial configuration.
  */
 boolean_t
 vdev_is_bootable(vdev_t *vd)
 {
-#if defined(__sun__) || defined(__sun)
-       /*
-        * Currently, we do not support RAID-Z or partial configuration.
-        * In addition, only a single top-level vdev is allowed and none of the
-        * leaves can be wholedisks.
-        */
-       int c;
-
        if (!vd->vdev_ops->vdev_op_leaf) {
-               char *vdev_type = vd->vdev_ops->vdev_op_type;
+               const char *vdev_type = vd->vdev_ops->vdev_op_type;
 
-               if (strcmp(vdev_type, VDEV_TYPE_ROOT) == 0 &&
-                   vd->vdev_children > 1) {
-                       return (B_FALSE);
-               } else if (strcmp(vdev_type, VDEV_TYPE_RAIDZ) == 0 ||
-                   strcmp(vdev_type, VDEV_TYPE_MISSING) == 0) {
+               if (strcmp(vdev_type, VDEV_TYPE_MISSING) == 0 ||
+                   strcmp(vdev_type, VDEV_TYPE_INDIRECT) == 0) {
                        return (B_FALSE);
                }
        }
 
-       for (c = 0; c < vd->vdev_children; c++) {
+       for (int c = 0; c < vd->vdev_children; c++) {
                if (!vdev_is_bootable(vd->vdev_child[c]))
                        return (B_FALSE);
        }
-#endif /* __sun__ || __sun */
        return (B_TRUE);
 }
 
-/*
- * Load the state from the original vdev tree (ovd) which
- * we've retrieved from the MOS config object. If the original
- * vdev was offline or faulted then we transfer that state to the
- * device in the current vdev tree (nvd).
- */
-void
-vdev_load_log_state(vdev_t *nvd, vdev_t *ovd)
+boolean_t
+vdev_is_concrete(vdev_t *vd)
 {
-       int c;
-
-       ASSERT(nvd->vdev_top->vdev_islog);
-       ASSERT(spa_config_held(nvd->vdev_spa,
-           SCL_STATE_ALL, RW_WRITER) == SCL_STATE_ALL);
-       ASSERT3U(nvd->vdev_guid, ==, ovd->vdev_guid);
-
-       for (c = 0; c < nvd->vdev_children; c++)
-               vdev_load_log_state(nvd->vdev_child[c], ovd->vdev_child[c]);
-
-       if (nvd->vdev_ops->vdev_op_leaf) {
-               /*
-                * Restore the persistent vdev state
-                */
-               nvd->vdev_offline = ovd->vdev_offline;
-               nvd->vdev_faulted = ovd->vdev_faulted;
-               nvd->vdev_degraded = ovd->vdev_degraded;
-               nvd->vdev_removed = ovd->vdev_removed;
+       vdev_ops_t *ops = vd->vdev_ops;
+       if (ops == &vdev_indirect_ops || ops == &vdev_hole_ops ||
+           ops == &vdev_missing_ops || ops == &vdev_root_ops) {
+               return (B_FALSE);
+       } else {
+               return (B_TRUE);
        }
 }
 
@@ -3593,13 +4587,11 @@ vdev_load_log_state(vdev_t *nvd, vdev_t *ovd)
 boolean_t
 vdev_log_state_valid(vdev_t *vd)
 {
-       int c;
-
        if (vd->vdev_ops->vdev_op_leaf && !vd->vdev_faulted &&
            !vd->vdev_removed)
                return (B_TRUE);
 
-       for (c = 0; c < vd->vdev_children; c++)
+       for (int c = 0; c < vd->vdev_children; c++)
                if (vdev_log_state_valid(vd->vdev_child[c]))
                        return (B_TRUE);
 
@@ -3614,8 +4606,13 @@ vdev_expand(vdev_t *vd, uint64_t txg)
 {
        ASSERT(vd->vdev_top == vd);
        ASSERT(spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER) == SCL_ALL);
+       ASSERT(vdev_is_concrete(vd));
 
-       if ((vd->vdev_asize >> vd->vdev_ms_shift) > vd->vdev_ms_count) {
+       vdev_set_deflate_ratio(vd);
+
+       if ((vd->vdev_asize >> vd->vdev_ms_shift) > vd->vdev_ms_count &&
+           vdev_is_concrete(vd)) {
+               vdev_metaslab_group_create(vd);
                VERIFY(vdev_metaslab_init(vd, txg) == 0);
                vdev_config_dirty(vd);
        }
@@ -3641,14 +4638,12 @@ vdev_split(vdev_t *vd)
 }
 
 void
-vdev_deadman(vdev_t *vd)
+vdev_deadman(vdev_t *vd, char *tag)
 {
-       int c;
-
-       for (c = 0; c < vd->vdev_children; c++) {
+       for (int c = 0; c < vd->vdev_children; c++) {
                vdev_t *cvd = vd->vdev_child[c];
 
-               vdev_deadman(cvd);
+               vdev_deadman(cvd, tag);
        }
 
        if (vd->vdev_ops->vdev_op_leaf) {
@@ -3660,36 +4655,75 @@ vdev_deadman(vdev_t *vd)
                        zio_t *fio;
                        uint64_t delta;
 
+                       zfs_dbgmsg("slow vdev: %s has %d active IOs",
+                           vd->vdev_path, avl_numnodes(&vq->vq_active_tree));
+
                        /*
                         * Look at the head of all the pending queues,
                         * if any I/O has been outstanding for longer than
-                        * the spa_deadman_synctime we log a zevent.
+                        * the spa_deadman_synctime invoke the deadman logic.
                         */
                        fio = avl_first(&vq->vq_active_tree);
                        delta = gethrtime() - fio->io_timestamp;
-                       if (delta > spa_deadman_synctime(spa)) {
-                               zfs_dbgmsg("SLOW IO: zio timestamp %lluns, "
-                                   "delta %lluns, last io %lluns",
-                                   fio->io_timestamp, delta,
-                                   vq->vq_io_complete_ts);
-                               zfs_ereport_post(FM_EREPORT_ZFS_DELAY,
-                                   spa, vd, fio, 0, 0);
-                       }
+                       if (delta > spa_deadman_synctime(spa))
+                               zio_deadman(fio, tag);
                }
                mutex_exit(&vq->vq_lock);
        }
 }
 
-#if defined(_KERNEL) && defined(HAVE_SPL)
+void
+vdev_set_deferred_resilver(spa_t *spa, vdev_t *vd)
+{
+       for (uint64_t i = 0; i < vd->vdev_children; i++)
+               vdev_set_deferred_resilver(spa, vd->vdev_child[i]);
+
+       if (!vd->vdev_ops->vdev_op_leaf || !vdev_writeable(vd) ||
+           range_tree_is_empty(vd->vdev_dtl[DTL_MISSING])) {
+               return;
+       }
+
+       vd->vdev_resilver_deferred = B_TRUE;
+       spa->spa_resilver_deferred = B_TRUE;
+}
+
+#if defined(_KERNEL)
 EXPORT_SYMBOL(vdev_fault);
 EXPORT_SYMBOL(vdev_degrade);
 EXPORT_SYMBOL(vdev_online);
 EXPORT_SYMBOL(vdev_offline);
 EXPORT_SYMBOL(vdev_clear);
 /* BEGIN CSTYLED */
-module_param(metaslabs_per_vdev, int, 0644);
-MODULE_PARM_DESC(metaslabs_per_vdev,
-       "Divide added vdev into approximately (but no more than) this number "
-       "of metaslabs");
+module_param(zfs_vdev_default_ms_count, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_default_ms_count,
+       "Target number of metaslabs per top-level vdev");
+
+module_param(zfs_vdev_min_ms_count, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_min_ms_count,
+       "Minimum number of metaslabs per top-level vdev");
+
+module_param(zfs_vdev_ms_count_limit, int, 0644);
+MODULE_PARM_DESC(zfs_vdev_ms_count_limit,
+       "Practical upper limit of total metaslabs per top-level vdev");
+
+module_param(zfs_slow_io_events_per_second, uint, 0644);
+MODULE_PARM_DESC(zfs_slow_io_events_per_second,
+       "Rate limit slow IO (delay) events to this many per second");
+
+module_param(zfs_checksum_events_per_second, uint, 0644);
+MODULE_PARM_DESC(zfs_checksum_events_per_second, "Rate limit checksum events "
+       "to this many checksum errors per second (do not set below zed"
+       "threshold).");
+
+module_param(zfs_scan_ignore_errors, int, 0644);
+MODULE_PARM_DESC(zfs_scan_ignore_errors,
+       "Ignore errors during resilver/scrub");
+
+module_param(vdev_validate_skip, int, 0644);
+MODULE_PARM_DESC(vdev_validate_skip,
+       "Bypass vdev_validate()");
+
+module_param(zfs_nocacheflush, int, 0644);
+MODULE_PARM_DESC(zfs_nocacheflush, "Disable cache flushes");
 /* END CSTYLED */
 #endif