vendor/openzfs/2.0-rc0-g184df27

1 files changed, 750 insertions, 0 deletions

diff --git a/module/zfs/vdev_initialize.c b/module/zfs/vdev_initialize.c
new file mode 100644
index 000000000000..ab711441d9ca
--- /dev/null
+++ b/module/zfs/vdev_initialize.c
@@ -0,0 +1,750 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright (c) 2016, 2019 by Delphix. All rights reserved.
+ */
+
+#include <sys/spa.h>
+#include <sys/spa_impl.h>
+#include <sys/txg.h>
+#include <sys/vdev_impl.h>
+#include <sys/metaslab_impl.h>
+#include <sys/dsl_synctask.h>
+#include <sys/zap.h>
+#include <sys/dmu_tx.h>
+#include <sys/vdev_initialize.h>
+
+/*
+ * Value that is written to disk during initialization.
+ */
+#ifdef _ILP32
+unsigned long zfs_initialize_value = 0xdeadbeefUL;
+#else
+unsigned long zfs_initialize_value = 0xdeadbeefdeadbeeeULL;
+#endif
+
+/* maximum number of I/Os outstanding per leaf vdev */
+int zfs_initialize_limit = 1;
+
+/* size of initializing writes; default 1MiB, see zfs_remove_max_segment */
+unsigned long zfs_initialize_chunk_size = 1024 * 1024;
+
+static boolean_t
+vdev_initialize_should_stop(vdev_t *vd)
+{
+	return (vd->vdev_initialize_exit_wanted || !vdev_writeable(vd) ||
+	    vd->vdev_detached || vd->vdev_top->vdev_removing);
+}
+
+static void
+vdev_initialize_zap_update_sync(void *arg, dmu_tx_t *tx)
+{
+	/*
+	 * We pass in the guid instead of the vdev_t since the vdev may
+	 * have been freed prior to the sync task being processed. This
+	 * happens when a vdev is detached as we call spa_config_vdev_exit(),
+	 * stop the initializing thread, schedule the sync task, and free
+	 * the vdev. Later when the scheduled sync task is invoked, it would
+	 * find that the vdev has been freed.
+	 */
+	uint64_t guid = *(uint64_t *)arg;
+	uint64_t txg = dmu_tx_get_txg(tx);
+	kmem_free(arg, sizeof (uint64_t));
+
+	vdev_t *vd = spa_lookup_by_guid(tx->tx_pool->dp_spa, guid, B_FALSE);
+	if (vd == NULL || vd->vdev_top->vdev_removing || !vdev_is_concrete(vd))
+		return;
+
+	uint64_t last_offset = vd->vdev_initialize_offset[txg & TXG_MASK];
+	vd->vdev_initialize_offset[txg & TXG_MASK] = 0;
+
+	VERIFY(vd->vdev_leaf_zap != 0);
+
+	objset_t *mos = vd->vdev_spa->spa_meta_objset;
+
+	if (last_offset > 0) {
+		vd->vdev_initialize_last_offset = last_offset;
+		VERIFY0(zap_update(mos, vd->vdev_leaf_zap,
+		    VDEV_LEAF_ZAP_INITIALIZE_LAST_OFFSET,
+		    sizeof (last_offset), 1, &last_offset, tx));
+	}
+	if (vd->vdev_initialize_action_time > 0) {
+		uint64_t val = (uint64_t)vd->vdev_initialize_action_time;
+		VERIFY0(zap_update(mos, vd->vdev_leaf_zap,
+		    VDEV_LEAF_ZAP_INITIALIZE_ACTION_TIME, sizeof (val),
+		    1, &val, tx));
+	}
+
+	uint64_t initialize_state = vd->vdev_initialize_state;
+	VERIFY0(zap_update(mos, vd->vdev_leaf_zap,
+	    VDEV_LEAF_ZAP_INITIALIZE_STATE, sizeof (initialize_state), 1,
+	    &initialize_state, tx));
+}
+
+static void
+vdev_initialize_change_state(vdev_t *vd, vdev_initializing_state_t new_state)
+{
+	ASSERT(MUTEX_HELD(&vd->vdev_initialize_lock));
+	spa_t *spa = vd->vdev_spa;
+
+	if (new_state == vd->vdev_initialize_state)
+		return;
+
+	/*
+	 * Copy the vd's guid, this will be freed by the sync task.
+	 */
+	uint64_t *guid = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
+	*guid = vd->vdev_guid;
+
+	/*
+	 * If we're suspending, then preserving the original start time.
+	 */
+	if (vd->vdev_initialize_state != VDEV_INITIALIZE_SUSPENDED) {
+		vd->vdev_initialize_action_time = gethrestime_sec();
+	}
+	vd->vdev_initialize_state = new_state;
+
+	dmu_tx_t *tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
+	VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
+	dsl_sync_task_nowait(spa_get_dsl(spa), vdev_initialize_zap_update_sync,
+	    guid, 2, ZFS_SPACE_CHECK_NONE, tx);
+
+	switch (new_state) {
+	case VDEV_INITIALIZE_ACTIVE:
+		spa_history_log_internal(spa, "initialize", tx,
+		    "vdev=%s activated", vd->vdev_path);
+		break;
+	case VDEV_INITIALIZE_SUSPENDED:
+		spa_history_log_internal(spa, "initialize", tx,
+		    "vdev=%s suspended", vd->vdev_path);
+		break;
+	case VDEV_INITIALIZE_CANCELED:
+		spa_history_log_internal(spa, "initialize", tx,
+		    "vdev=%s canceled", vd->vdev_path);
+		break;
+	case VDEV_INITIALIZE_COMPLETE:
+		spa_history_log_internal(spa, "initialize", tx,
+		    "vdev=%s complete", vd->vdev_path);
+		break;
+	default:
+		panic("invalid state %llu", (unsigned long long)new_state);
+	}
+
+	dmu_tx_commit(tx);
+
+	if (new_state != VDEV_INITIALIZE_ACTIVE)
+		spa_notify_waiters(spa);
+}
+
+static void
+vdev_initialize_cb(zio_t *zio)
+{
+	vdev_t *vd = zio->io_vd;
+	mutex_enter(&vd->vdev_initialize_io_lock);
+	if (zio->io_error == ENXIO && !vdev_writeable(vd)) {
+		/*
+		 * The I/O failed because the vdev was unavailable; roll the
+		 * last offset back. (This works because spa_sync waits on
+		 * spa_txg_zio before it runs sync tasks.)
+		 */
+		uint64_t *off =
+		    &vd->vdev_initialize_offset[zio->io_txg & TXG_MASK];
+		*off = MIN(*off, zio->io_offset);
+	} else {
+		/*
+		 * Since initializing is best-effort, we ignore I/O errors and
+		 * rely on vdev_probe to determine if the errors are more
+		 * critical.
+		 */
+		if (zio->io_error != 0)
+			vd->vdev_stat.vs_initialize_errors++;
+
+		vd->vdev_initialize_bytes_done += zio->io_orig_size;
+	}
+	ASSERT3U(vd->vdev_initialize_inflight, >, 0);
+	vd->vdev_initialize_inflight--;
+	cv_broadcast(&vd->vdev_initialize_io_cv);
+	mutex_exit(&vd->vdev_initialize_io_lock);
+
+	spa_config_exit(vd->vdev_spa, SCL_STATE_ALL, vd);
+}
+
+/* Takes care of physical writing and limiting # of concurrent ZIOs. */
+static int
+vdev_initialize_write(vdev_t *vd, uint64_t start, uint64_t size, abd_t *data)
+{
+	spa_t *spa = vd->vdev_spa;
+
+	/* Limit inflight initializing I/Os */
+	mutex_enter(&vd->vdev_initialize_io_lock);
+	while (vd->vdev_initialize_inflight >= zfs_initialize_limit) {
+		cv_wait(&vd->vdev_initialize_io_cv,
+		    &vd->vdev_initialize_io_lock);
+	}
+	vd->vdev_initialize_inflight++;
+	mutex_exit(&vd->vdev_initialize_io_lock);
+
+	dmu_tx_t *tx = dmu_tx_create_dd(spa_get_dsl(spa)->dp_mos_dir);
+	VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
+	uint64_t txg = dmu_tx_get_txg(tx);
+
+	spa_config_enter(spa, SCL_STATE_ALL, vd, RW_READER);
+	mutex_enter(&vd->vdev_initialize_lock);
+
+	if (vd->vdev_initialize_offset[txg & TXG_MASK] == 0) {
+		uint64_t *guid = kmem_zalloc(sizeof (uint64_t), KM_SLEEP);
+		*guid = vd->vdev_guid;
+
+		/* This is the first write of this txg. */
+		dsl_sync_task_nowait(spa_get_dsl(spa),
+		    vdev_initialize_zap_update_sync, guid, 2,
+		    ZFS_SPACE_CHECK_RESERVED, tx);
+	}
+
+	/*
+	 * We know the vdev struct will still be around since all
+	 * consumers of vdev_free must stop the initialization first.
+	 */
+	if (vdev_initialize_should_stop(vd)) {
+		mutex_enter(&vd->vdev_initialize_io_lock);
+		ASSERT3U(vd->vdev_initialize_inflight, >, 0);
+		vd->vdev_initialize_inflight--;
+		mutex_exit(&vd->vdev_initialize_io_lock);
+		spa_config_exit(vd->vdev_spa, SCL_STATE_ALL, vd);
+		mutex_exit(&vd->vdev_initialize_lock);
+		dmu_tx_commit(tx);
+		return (SET_ERROR(EINTR));
+	}
+	mutex_exit(&vd->vdev_initialize_lock);
+
+	vd->vdev_initialize_offset[txg & TXG_MASK] = start + size;
+	zio_nowait(zio_write_phys(spa->spa_txg_zio[txg & TXG_MASK], vd, start,
+	    size, data, ZIO_CHECKSUM_OFF, vdev_initialize_cb, NULL,
+	    ZIO_PRIORITY_INITIALIZING, ZIO_FLAG_CANFAIL, B_FALSE));
+	/* vdev_initialize_cb releases SCL_STATE_ALL */
+
+	dmu_tx_commit(tx);
+
+	return (0);
+}
+
+/*
+ * Callback to fill each ABD chunk with zfs_initialize_value. len must be
+ * divisible by sizeof (uint64_t), and buf must be 8-byte aligned. The ABD
+ * allocation will guarantee these for us.
+ */
+/* ARGSUSED */
+static int
+vdev_initialize_block_fill(void *buf, size_t len, void *unused)
+{
+	ASSERT0(len % sizeof (uint64_t));
+#ifdef _ILP32
+	for (uint64_t i = 0; i < len; i += sizeof (uint32_t)) {
+		*(uint32_t *)((char *)(buf) + i) = zfs_initialize_value;
+	}
+#else
+	for (uint64_t i = 0; i < len; i += sizeof (uint64_t)) {
+		*(uint64_t *)((char *)(buf) + i) = zfs_initialize_value;
+	}
+#endif
+	return (0);
+}
+
+static abd_t *
+vdev_initialize_block_alloc(void)
+{
+	/* Allocate ABD for filler data */
+	abd_t *data = abd_alloc_for_io(zfs_initialize_chunk_size, B_FALSE);
+
+	ASSERT0(zfs_initialize_chunk_size % sizeof (uint64_t));
+	(void) abd_iterate_func(data, 0, zfs_initialize_chunk_size,
+	    vdev_initialize_block_fill, NULL);
+
+	return (data);
+}
+
+static void
+vdev_initialize_block_free(abd_t *data)
+{
+	abd_free(data);
+}
+
+static int
+vdev_initialize_ranges(vdev_t *vd, abd_t *data)
+{
+	range_tree_t *rt = vd->vdev_initialize_tree;
+	zfs_btree_t *bt = &rt->rt_root;
+	zfs_btree_index_t where;
+
+	for (range_seg_t *rs = zfs_btree_first(bt, &where); rs != NULL;
+	    rs = zfs_btree_next(bt, &where, &where)) {
+		uint64_t size = rs_get_end(rs, rt) - rs_get_start(rs, rt);
+
+		/* Split range into legally-sized physical chunks */
+		uint64_t writes_required =
+		    ((size - 1) / zfs_initialize_chunk_size) + 1;
+
+		for (uint64_t w = 0; w < writes_required; w++) {
+			int error;
+
+			error = vdev_initialize_write(vd,
+			    VDEV_LABEL_START_SIZE + rs_get_start(rs, rt) +
+			    (w * zfs_initialize_chunk_size),
+			    MIN(size - (w * zfs_initialize_chunk_size),
+			    zfs_initialize_chunk_size), data);
+			if (error != 0)
+				return (error);
+		}
+	}
+	return (0);
+}
+
+static void
+vdev_initialize_calculate_progress(vdev_t *vd)
+{
+	ASSERT(spa_config_held(vd->vdev_spa, SCL_CONFIG, RW_READER) ||
+	    spa_config_held(vd->vdev_spa, SCL_CONFIG, RW_WRITER));
+	ASSERT(vd->vdev_leaf_zap != 0);
+
+	vd->vdev_initialize_bytes_est = 0;
+	vd->vdev_initialize_bytes_done = 0;
+
+	for (uint64_t i = 0; i < vd->vdev_top->vdev_ms_count; i++) {
+		metaslab_t *msp = vd->vdev_top->vdev_ms[i];
+		mutex_enter(&msp->ms_lock);
+
+		uint64_t ms_free = msp->ms_size -
+		    metaslab_allocated_space(msp);
+
+		if (vd->vdev_top->vdev_ops == &vdev_raidz_ops)
+			ms_free /= vd->vdev_top->vdev_children;
+
+		/*
+		 * Convert the metaslab range to a physical range
+		 * on our vdev. We use this to determine if we are
+		 * in the middle of this metaslab range.
+		 */
+		range_seg64_t logical_rs, physical_rs;
+		logical_rs.rs_start = msp->ms_start;
+		logical_rs.rs_end = msp->ms_start + msp->ms_size;
+		vdev_xlate(vd, &logical_rs, &physical_rs);
+
+		if (vd->vdev_initialize_last_offset <= physical_rs.rs_start) {
+			vd->vdev_initialize_bytes_est += ms_free;
+			mutex_exit(&msp->ms_lock);
+			continue;
+		} else if (vd->vdev_initialize_last_offset >
+		    physical_rs.rs_end) {
+			vd->vdev_initialize_bytes_done += ms_free;
+			vd->vdev_initialize_bytes_est += ms_free;
+			mutex_exit(&msp->ms_lock);
+			continue;
+		}
+
+		/*
+		 * If we get here, we're in the middle of initializing this
+		 * metaslab. Load it and walk the free tree for more accurate
+		 * progress estimation.
+		 */
+		VERIFY0(metaslab_load(msp));
+
+		zfs_btree_index_t where;
+		range_tree_t *rt = msp->ms_allocatable;
+		for (range_seg_t *rs =
+		    zfs_btree_first(&rt->rt_root, &where); rs;
+		    rs = zfs_btree_next(&rt->rt_root, &where,
+		    &where)) {
+			logical_rs.rs_start = rs_get_start(rs, rt);
+			logical_rs.rs_end = rs_get_end(rs, rt);
+			vdev_xlate(vd, &logical_rs, &physical_rs);
+
+			uint64_t size = physical_rs.rs_end -
+			    physical_rs.rs_start;
+			vd->vdev_initialize_bytes_est += size;
+			if (vd->vdev_initialize_last_offset >
+			    physical_rs.rs_end) {
+				vd->vdev_initialize_bytes_done += size;
+			} else if (vd->vdev_initialize_last_offset >
+			    physical_rs.rs_start &&
+			    vd->vdev_initialize_last_offset <
+			    physical_rs.rs_end) {
+				vd->vdev_initialize_bytes_done +=
+				    vd->vdev_initialize_last_offset -
+				    physical_rs.rs_start;
+			}
+		}
+		mutex_exit(&msp->ms_lock);
+	}
+}
+
+static int
+vdev_initialize_load(vdev_t *vd)
+{
+	int err = 0;
+	ASSERT(spa_config_held(vd->vdev_spa, SCL_CONFIG, RW_READER) ||
+	    spa_config_held(vd->vdev_spa, SCL_CONFIG, RW_WRITER));
+	ASSERT(vd->vdev_leaf_zap != 0);
+
+	if (vd->vdev_initialize_state == VDEV_INITIALIZE_ACTIVE ||
+	    vd->vdev_initialize_state == VDEV_INITIALIZE_SUSPENDED) {
+		err = zap_lookup(vd->vdev_spa->spa_meta_objset,
+		    vd->vdev_leaf_zap, VDEV_LEAF_ZAP_INITIALIZE_LAST_OFFSET,
+		    sizeof (vd->vdev_initialize_last_offset), 1,
+		    &vd->vdev_initialize_last_offset);
+		if (err == ENOENT) {
+			vd->vdev_initialize_last_offset = 0;
+			err = 0;
+		}
+	}
+
+	vdev_initialize_calculate_progress(vd);
+	return (err);
+}
+
+/*
+ * Convert the logical range into a physical range and add it to our
+ * avl tree.
+ */
+static void
+vdev_initialize_range_add(void *arg, uint64_t start, uint64_t size)
+{
+	vdev_t *vd = arg;
+	range_seg64_t logical_rs, physical_rs;
+	logical_rs.rs_start = start;
+	logical_rs.rs_end = start + size;
+
+	ASSERT(vd->vdev_ops->vdev_op_leaf);
+	vdev_xlate(vd, &logical_rs, &physical_rs);
+
+	IMPLY(vd->vdev_top == vd,
+	    logical_rs.rs_start == physical_rs.rs_start);
+	IMPLY(vd->vdev_top == vd,
+	    logical_rs.rs_end == physical_rs.rs_end);
+
+	/* Only add segments that we have not visited yet */
+	if (physical_rs.rs_end <= vd->vdev_initialize_last_offset)
+		return;
+
+	/* Pick up where we left off mid-range. */
+	if (vd->vdev_initialize_last_offset > physical_rs.rs_start) {
+		zfs_dbgmsg("range write: vd %s changed (%llu, %llu) to "
+		    "(%llu, %llu)", vd->vdev_path,
+		    (u_longlong_t)physical_rs.rs_start,
+		    (u_longlong_t)physical_rs.rs_end,
+		    (u_longlong_t)vd->vdev_initialize_last_offset,
+		    (u_longlong_t)physical_rs.rs_end);
+		ASSERT3U(physical_rs.rs_end, >,
+		    vd->vdev_initialize_last_offset);
+		physical_rs.rs_start = vd->vdev_initialize_last_offset;
+	}
+	ASSERT3U(physical_rs.rs_end, >=, physical_rs.rs_start);
+
+	/*
+	 * With raidz, it's possible that the logical range does not live on
+	 * this leaf vdev. We only add the physical range to this vdev's if it
+	 * has a length greater than 0.
+	 */
+	if (physical_rs.rs_end > physical_rs.rs_start) {
+		range_tree_add(vd->vdev_initialize_tree, physical_rs.rs_start,
+		    physical_rs.rs_end - physical_rs.rs_start);
+	} else {
+		ASSERT3U(physical_rs.rs_end, ==, physical_rs.rs_start);
+	}
+}
+
+static void
+vdev_initialize_thread(void *arg)
+{
+	vdev_t *vd = arg;
+	spa_t *spa = vd->vdev_spa;
+	int error = 0;
+	uint64_t ms_count = 0;
+
+	ASSERT(vdev_is_concrete(vd));
+	spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+
+	vd->vdev_initialize_last_offset = 0;
+	VERIFY0(vdev_initialize_load(vd));
+
+	abd_t *deadbeef = vdev_initialize_block_alloc();
+
+	vd->vdev_initialize_tree = range_tree_create(NULL, RANGE_SEG64, NULL,
+	    0, 0);
+
+	for (uint64_t i = 0; !vd->vdev_detached &&
+	    i < vd->vdev_top->vdev_ms_count; i++) {
+		metaslab_t *msp = vd->vdev_top->vdev_ms[i];
+		boolean_t unload_when_done = B_FALSE;
+
+		/*
+		 * If we've expanded the top-level vdev or it's our
+		 * first pass, calculate our progress.
+		 */
+		if (vd->vdev_top->vdev_ms_count != ms_count) {
+			vdev_initialize_calculate_progress(vd);
+			ms_count = vd->vdev_top->vdev_ms_count;
+		}
+
+		spa_config_exit(spa, SCL_CONFIG, FTAG);
+		metaslab_disable(msp);
+		mutex_enter(&msp->ms_lock);
+		if (!msp->ms_loaded && !msp->ms_loading)
+			unload_when_done = B_TRUE;
+		VERIFY0(metaslab_load(msp));
+
+		range_tree_walk(msp->ms_allocatable, vdev_initialize_range_add,
+		    vd);
+		mutex_exit(&msp->ms_lock);
+
+		error = vdev_initialize_ranges(vd, deadbeef);
+		metaslab_enable(msp, B_TRUE, unload_when_done);
+		spa_config_enter(spa, SCL_CONFIG, FTAG, RW_READER);
+
+		range_tree_vacate(vd->vdev_initialize_tree, NULL, NULL);
+		if (error != 0)
+			break;
+	}
+
+	spa_config_exit(spa, SCL_CONFIG, FTAG);
+	mutex_enter(&vd->vdev_initialize_io_lock);
+	while (vd->vdev_initialize_inflight > 0) {
+		cv_wait(&vd->vdev_initialize_io_cv,
+		    &vd->vdev_initialize_io_lock);
+	}
+	mutex_exit(&vd->vdev_initialize_io_lock);
+
+	range_tree_destroy(vd->vdev_initialize_tree);
+	vdev_initialize_block_free(deadbeef);
+	vd->vdev_initialize_tree = NULL;
+
+	mutex_enter(&vd->vdev_initialize_lock);
+	if (!vd->vdev_initialize_exit_wanted && vdev_writeable(vd)) {
+		vdev_initialize_change_state(vd, VDEV_INITIALIZE_COMPLETE);
+	}
+	ASSERT(vd->vdev_initialize_thread != NULL ||
+	    vd->vdev_initialize_inflight == 0);
+
+	/*
+	 * Drop the vdev_initialize_lock while we sync out the
+	 * txg since it's possible that a device might be trying to
+	 * come online and must check to see if it needs to restart an
+	 * initialization. That thread will be holding the spa_config_lock
+	 * which would prevent the txg_wait_synced from completing.
+	 */
+	mutex_exit(&vd->vdev_initialize_lock);
+	txg_wait_synced(spa_get_dsl(spa), 0);
+	mutex_enter(&vd->vdev_initialize_lock);
+
+	vd->vdev_initialize_thread = NULL;
+	cv_broadcast(&vd->vdev_initialize_cv);
+	mutex_exit(&vd->vdev_initialize_lock);
+
+	thread_exit();
+}
+
+/*
+ * Initiates a device. Caller must hold vdev_initialize_lock.
+ * Device must be a leaf and not already be initializing.
+ */
+void
+vdev_initialize(vdev_t *vd)
+{
+	ASSERT(MUTEX_HELD(&vd->vdev_initialize_lock));
+	ASSERT(vd->vdev_ops->vdev_op_leaf);
+	ASSERT(vdev_is_concrete(vd));
+	ASSERT3P(vd->vdev_initialize_thread, ==, NULL);
+	ASSERT(!vd->vdev_detached);
+	ASSERT(!vd->vdev_initialize_exit_wanted);
+	ASSERT(!vd->vdev_top->vdev_removing);
+
+	vdev_initialize_change_state(vd, VDEV_INITIALIZE_ACTIVE);
+	vd->vdev_initialize_thread = thread_create(NULL, 0,
+	    vdev_initialize_thread, vd, 0, &p0, TS_RUN, maxclsyspri);
+}
+
+/*
+ * Wait for the initialize thread to be terminated (cancelled or stopped).
+ */
+static void
+vdev_initialize_stop_wait_impl(vdev_t *vd)
+{
+	ASSERT(MUTEX_HELD(&vd->vdev_initialize_lock));
+
+	while (vd->vdev_initialize_thread != NULL)
+		cv_wait(&vd->vdev_initialize_cv, &vd->vdev_initialize_lock);
+
+	ASSERT3P(vd->vdev_initialize_thread, ==, NULL);
+	vd->vdev_initialize_exit_wanted = B_FALSE;
+}
+
+/*
+ * Wait for vdev initialize threads which were either to cleanly exit.
+ */
+void
+vdev_initialize_stop_wait(spa_t *spa, list_t *vd_list)
+{
+	vdev_t *vd;
+
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
+
+	while ((vd = list_remove_head(vd_list)) != NULL) {
+		mutex_enter(&vd->vdev_initialize_lock);
+		vdev_initialize_stop_wait_impl(vd);
+		mutex_exit(&vd->vdev_initialize_lock);
+	}
+}
+
+/*
+ * Stop initializing a device, with the resultant initializing state being
+ * tgt_state.  For blocking behavior pass NULL for vd_list.  Otherwise, when
+ * a list_t is provided the stopping vdev is inserted in to the list.  Callers
+ * are then required to call vdev_initialize_stop_wait() to block for all the
+ * initialization threads to exit.  The caller must hold vdev_initialize_lock
+ * and must not be writing to the spa config, as the initializing thread may
+ * try to enter the config as a reader before exiting.
+ */
+void
+vdev_initialize_stop(vdev_t *vd, vdev_initializing_state_t tgt_state,
+    list_t *vd_list)
+{
+	ASSERT(!spa_config_held(vd->vdev_spa, SCL_CONFIG|SCL_STATE, RW_WRITER));
+	ASSERT(MUTEX_HELD(&vd->vdev_initialize_lock));
+	ASSERT(vd->vdev_ops->vdev_op_leaf);
+	ASSERT(vdev_is_concrete(vd));
+
+	/*
+	 * Allow cancel requests to proceed even if the initialize thread
+	 * has stopped.
+	 */
+	if (vd->vdev_initialize_thread == NULL &&
+	    tgt_state != VDEV_INITIALIZE_CANCELED) {
+		return;
+	}
+
+	vdev_initialize_change_state(vd, tgt_state);
+	vd->vdev_initialize_exit_wanted = B_TRUE;
+
+	if (vd_list == NULL) {
+		vdev_initialize_stop_wait_impl(vd);
+	} else {
+		ASSERT(MUTEX_HELD(&spa_namespace_lock));
+		list_insert_tail(vd_list, vd);
+	}
+}
+
+static void
+vdev_initialize_stop_all_impl(vdev_t *vd, vdev_initializing_state_t tgt_state,
+    list_t *vd_list)
+{
+	if (vd->vdev_ops->vdev_op_leaf && vdev_is_concrete(vd)) {
+		mutex_enter(&vd->vdev_initialize_lock);
+		vdev_initialize_stop(vd, tgt_state, vd_list);
+		mutex_exit(&vd->vdev_initialize_lock);
+		return;
+	}
+
+	for (uint64_t i = 0; i < vd->vdev_children; i++) {
+		vdev_initialize_stop_all_impl(vd->vdev_child[i], tgt_state,
+		    vd_list);
+	}
+}
+
+/*
+ * Convenience function to stop initializing of a vdev tree and set all
+ * initialize thread pointers to NULL.
+ */
+void
+vdev_initialize_stop_all(vdev_t *vd, vdev_initializing_state_t tgt_state)
+{
+	spa_t *spa = vd->vdev_spa;
+	list_t vd_list;
+
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
+
+	list_create(&vd_list, sizeof (vdev_t),
+	    offsetof(vdev_t, vdev_initialize_node));
+
+	vdev_initialize_stop_all_impl(vd, tgt_state, &vd_list);
+	vdev_initialize_stop_wait(spa, &vd_list);
+
+	if (vd->vdev_spa->spa_sync_on) {
+		/* Make sure that our state has been synced to disk */
+		txg_wait_synced(spa_get_dsl(vd->vdev_spa), 0);
+	}
+
+	list_destroy(&vd_list);
+}
+
+void
+vdev_initialize_restart(vdev_t *vd)
+{
+	ASSERT(MUTEX_HELD(&spa_namespace_lock));
+	ASSERT(!spa_config_held(vd->vdev_spa, SCL_ALL, RW_WRITER));
+
+	if (vd->vdev_leaf_zap != 0) {
+		mutex_enter(&vd->vdev_initialize_lock);
+		uint64_t initialize_state = VDEV_INITIALIZE_NONE;
+		int err = zap_lookup(vd->vdev_spa->spa_meta_objset,
+		    vd->vdev_leaf_zap, VDEV_LEAF_ZAP_INITIALIZE_STATE,
+		    sizeof (initialize_state), 1, &initialize_state);
+		ASSERT(err == 0 || err == ENOENT);
+		vd->vdev_initialize_state = initialize_state;
+
+		uint64_t timestamp = 0;
+		err = zap_lookup(vd->vdev_spa->spa_meta_objset,
+		    vd->vdev_leaf_zap, VDEV_LEAF_ZAP_INITIALIZE_ACTION_TIME,
+		    sizeof (timestamp), 1, &timestamp);
+		ASSERT(err == 0 || err == ENOENT);
+		vd->vdev_initialize_action_time = timestamp;
+
+		if (vd->vdev_initialize_state == VDEV_INITIALIZE_SUSPENDED ||
+		    vd->vdev_offline) {
+			/* load progress for reporting, but don't resume */
+			VERIFY0(vdev_initialize_load(vd));
+		} else if (vd->vdev_initialize_state ==
+		    VDEV_INITIALIZE_ACTIVE && vdev_writeable(vd) &&
+		    !vd->vdev_top->vdev_removing &&
+		    vd->vdev_initialize_thread == NULL) {
+			vdev_initialize(vd);
+		}
+
+		mutex_exit(&vd->vdev_initialize_lock);
+	}
+
+	for (uint64_t i = 0; i < vd->vdev_children; i++) {
+		vdev_initialize_restart(vd->vdev_child[i]);
+	}
+}
+
+EXPORT_SYMBOL(vdev_initialize);
+EXPORT_SYMBOL(vdev_initialize_stop);
+EXPORT_SYMBOL(vdev_initialize_stop_all);
+EXPORT_SYMBOL(vdev_initialize_stop_wait);
+EXPORT_SYMBOL(vdev_initialize_restart);
+
+/* BEGIN CSTYLED */
+ZFS_MODULE_PARAM(zfs, zfs_, initialize_value, ULONG, ZMOD_RW,
+	"Value written during zpool initialize");
+
+ZFS_MODULE_PARAM(zfs, zfs_, initialize_chunk_size, ULONG, ZMOD_RW,
+	"Size in bytes of writes by zpool initialize");
+/* END CSTYLED */