10500 Refactor dmu_recv into its own file

Portions contributed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Igor Kozhukhov <igor@dilos.org>
Reviewed by: Toomas Soome <tsoome@me.com>
Reviewed by: Kody Kantor <kody.kantor@joyent.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>

8 files changed, 2329 insertions, 2232 deletions

diff --git a/usr/src/uts/common/Makefile.files b/usr/src/uts/common/Makefile.files
index 60f26ae2d9..df5e864377 100644
--- a/usr/src/uts/common/Makefile.files
+++ b/usr/src/uts/common/Makefile.files
@@ -25,7 +25,7 @@
 # Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
 # Copyright 2018 Nexenta Systems, Inc.
 # Copyright 2016 Garrett D'Amore <garrett@damore.org>
-# Copyright (c) 2017, Joyent, Inc.
+# Copyright 2019 Joyent, Inc.
 # Copyright 2016 OmniTI Computer Consulting, Inc.  All rights reserved.
 # Copyright 2016 Hans Rosenfeld <rosenfeld@grumpf.hope-2000.org>
 #
@@ -1327,6 +1327,7 @@ ZFS_COMMON_OBJS +=		\
 	ddt_zap.o		\
 	dmu.o			\
 	dmu_diff.o		\
+	dmu_recv.o		\
 	dmu_send.o		\
 	dmu_object.o		\
 	dmu_objset.o		\
diff --git a/usr/src/uts/common/fs/zfs/dmu_recv.c b/usr/src/uts/common/fs/zfs/dmu_recv.c
new file mode 100644
index 0000000000..542bb42f3f
--- /dev/null
+++ b/usr/src/uts/common/fs/zfs/dmu_recv.c
@@ -0,0 +1,2260 @@
+/*
+ * 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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2011, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2014, Joyent, Inc. All rights reserved.
+ * Copyright 2014 HybridCluster. All rights reserved.
+ * Copyright 2016 RackTop Systems.
+ * Copyright (c) 2014 Integros [integros.com]
+ */
+
+#include <sys/dmu.h>
+#include <sys/dmu_impl.h>
+#include <sys/dmu_tx.h>
+#include <sys/dbuf.h>
+#include <sys/dnode.h>
+#include <sys/zfs_context.h>
+#include <sys/dmu_objset.h>
+#include <sys/dmu_traverse.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_prop.h>
+#include <sys/dsl_pool.h>
+#include <sys/dsl_synctask.h>
+#include <sys/zfs_ioctl.h>
+#include <sys/zap.h>
+#include <sys/zio_checksum.h>
+#include <sys/zfs_znode.h>
+#include <zfs_fletcher.h>
+#include <sys/avl.h>
+#include <sys/ddt.h>
+#include <sys/zfs_onexit.h>
+#include <sys/dmu_recv.h>
+#include <sys/dsl_destroy.h>
+#include <sys/blkptr.h>
+#include <sys/dsl_bookmark.h>
+#include <sys/zfeature.h>
+#include <sys/bqueue.h>
+
+int zfs_recv_queue_length = SPA_MAXBLOCKSIZE;
+
+static char *dmu_recv_tag = "dmu_recv_tag";
+const char *recv_clone_name = "%recv";
+
+static void byteswap_record(dmu_replay_record_t *drr);
+
+typedef struct dmu_recv_begin_arg {
+	const char *drba_origin;
+	dmu_recv_cookie_t *drba_cookie;
+	cred_t *drba_cred;
+	uint64_t drba_snapobj;
+} dmu_recv_begin_arg_t;
+
+static int
+recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
+    uint64_t fromguid)
+{
+	uint64_t val;
+	int error;
+	dsl_pool_t *dp = ds->ds_dir->dd_pool;
+
+	/* temporary clone name must not exist */
+	error = zap_lookup(dp->dp_meta_objset,
+	    dsl_dir_phys(ds->ds_dir)->dd_child_dir_zapobj, recv_clone_name,
+	    8, 1, &val);
+	if (error != ENOENT)
+		return (error == 0 ? EBUSY : error);
+
+	/* new snapshot name must not exist */
+	error = zap_lookup(dp->dp_meta_objset,
+	    dsl_dataset_phys(ds)->ds_snapnames_zapobj,
+	    drba->drba_cookie->drc_tosnap, 8, 1, &val);
+	if (error != ENOENT)
+		return (error == 0 ? EEXIST : error);
+
+	/*
+	 * Check snapshot limit before receiving. We'll recheck again at the
+	 * end, but might as well abort before receiving if we're already over
+	 * the limit.
+	 *
+	 * Note that we do not check the file system limit with
+	 * dsl_dir_fscount_check because the temporary %clones don't count
+	 * against that limit.
+	 */
+	error = dsl_fs_ss_limit_check(ds->ds_dir, 1, ZFS_PROP_SNAPSHOT_LIMIT,
+	    NULL, drba->drba_cred);
+	if (error != 0)
+		return (error);
+
+	if (fromguid != 0) {
+		dsl_dataset_t *snap;
+		uint64_t obj = dsl_dataset_phys(ds)->ds_prev_snap_obj;
+
+		/* Find snapshot in this dir that matches fromguid. */
+		while (obj != 0) {
+			error = dsl_dataset_hold_obj(dp, obj, FTAG,
+			    &snap);
+			if (error != 0)
+				return (SET_ERROR(ENODEV));
+			if (snap->ds_dir != ds->ds_dir) {
+				dsl_dataset_rele(snap, FTAG);
+				return (SET_ERROR(ENODEV));
+			}
+			if (dsl_dataset_phys(snap)->ds_guid == fromguid)
+				break;
+			obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
+			dsl_dataset_rele(snap, FTAG);
+		}
+		if (obj == 0)
+			return (SET_ERROR(ENODEV));
+
+		if (drba->drba_cookie->drc_force) {
+			drba->drba_snapobj = obj;
+		} else {
+			/*
+			 * If we are not forcing, there must be no
+			 * changes since fromsnap.
+			 */
+			if (dsl_dataset_modified_since_snap(ds, snap)) {
+				dsl_dataset_rele(snap, FTAG);
+				return (SET_ERROR(ETXTBSY));
+			}
+			drba->drba_snapobj = ds->ds_prev->ds_object;
+		}
+
+		dsl_dataset_rele(snap, FTAG);
+	} else {
+		/* if full, then must be forced */
+		if (!drba->drba_cookie->drc_force)
+			return (SET_ERROR(EEXIST));
+		/* start from $ORIGIN@$ORIGIN, if supported */
+		drba->drba_snapobj = dp->dp_origin_snap != NULL ?
+		    dp->dp_origin_snap->ds_object : 0;
+	}
+
+	return (0);
+
+}
+
+static int
+dmu_recv_begin_check(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_begin_arg_t *drba = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
+	uint64_t fromguid = drrb->drr_fromguid;
+	int flags = drrb->drr_flags;
+	int error;
+	uint64_t featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
+	dsl_dataset_t *ds;
+	const char *tofs = drba->drba_cookie->drc_tofs;
+
+	/* already checked */
+	ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
+	ASSERT(!(featureflags & DMU_BACKUP_FEATURE_RESUMING));
+
+	if (DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
+	    DMU_COMPOUNDSTREAM ||
+	    drrb->drr_type >= DMU_OST_NUMTYPES ||
+	    ((flags & DRR_FLAG_CLONE) && drba->drba_origin == NULL))
+		return (SET_ERROR(EINVAL));
+
+	/* Verify pool version supports SA if SA_SPILL feature set */
+	if ((featureflags & DMU_BACKUP_FEATURE_SA_SPILL) &&
+	    spa_version(dp->dp_spa) < SPA_VERSION_SA)
+		return (SET_ERROR(ENOTSUP));
+
+	if (drba->drba_cookie->drc_resumable &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EXTENSIBLE_DATASET))
+		return (SET_ERROR(ENOTSUP));
+
+	/*
+	 * The receiving code doesn't know how to translate a WRITE_EMBEDDED
+	 * record to a plain WRITE record, so the pool must have the
+	 * EMBEDDED_DATA feature enabled if the stream has WRITE_EMBEDDED
+	 * records.  Same with WRITE_EMBEDDED records that use LZ4 compression.
+	 */
+	if ((featureflags & DMU_BACKUP_FEATURE_EMBED_DATA) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EMBEDDED_DATA))
+		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LZ4) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LZ4_COMPRESS))
+		return (SET_ERROR(ENOTSUP));
+
+	/*
+	 * The receiving code doesn't know how to translate large blocks
+	 * to smaller ones, so the pool must have the LARGE_BLOCKS
+	 * feature enabled if the stream has LARGE_BLOCKS. Same with
+	 * large dnodes.
+	 */
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
+		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
+		return (SET_ERROR(ENOTSUP));
+
+	error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
+	if (error == 0) {
+		/* target fs already exists; recv into temp clone */
+
+		/* Can't recv a clone into an existing fs */
+		if (flags & DRR_FLAG_CLONE || drba->drba_origin) {
+			dsl_dataset_rele(ds, FTAG);
+			return (SET_ERROR(EINVAL));
+		}
+
+		error = recv_begin_check_existing_impl(drba, ds, fromguid);
+		dsl_dataset_rele(ds, FTAG);
+	} else if (error == ENOENT) {
+		/* target fs does not exist; must be a full backup or clone */
+		char buf[ZFS_MAX_DATASET_NAME_LEN];
+
+		/*
+		 * If it's a non-clone incremental, we are missing the
+		 * target fs, so fail the recv.
+		 */
+		if (fromguid != 0 && !(flags & DRR_FLAG_CLONE ||
+		    drba->drba_origin))
+			return (SET_ERROR(ENOENT));
+
+		/*
+		 * If we're receiving a full send as a clone, and it doesn't
+		 * contain all the necessary free records and freeobject
+		 * records, reject it.
+		 */
+		if (fromguid == 0 && drba->drba_origin &&
+		    !(flags & DRR_FLAG_FREERECORDS))
+			return (SET_ERROR(EINVAL));
+
+		/* Open the parent of tofs */
+		ASSERT3U(strlen(tofs), <, sizeof (buf));
+		(void) strlcpy(buf, tofs, strrchr(tofs, '/') - tofs + 1);
+		error = dsl_dataset_hold(dp, buf, FTAG, &ds);
+		if (error != 0)
+			return (error);
+
+		/*
+		 * Check filesystem and snapshot limits before receiving. We'll
+		 * recheck snapshot limits again at the end (we create the
+		 * filesystems and increment those counts during begin_sync).
+		 */
+		error = dsl_fs_ss_limit_check(ds->ds_dir, 1,
+		    ZFS_PROP_FILESYSTEM_LIMIT, NULL, drba->drba_cred);
+		if (error != 0) {
+			dsl_dataset_rele(ds, FTAG);
+			return (error);
+		}
+
+		error = dsl_fs_ss_limit_check(ds->ds_dir, 1,
+		    ZFS_PROP_SNAPSHOT_LIMIT, NULL, drba->drba_cred);
+		if (error != 0) {
+			dsl_dataset_rele(ds, FTAG);
+			return (error);
+		}
+
+		if (drba->drba_origin != NULL) {
+			dsl_dataset_t *origin;
+			error = dsl_dataset_hold(dp, drba->drba_origin,
+			    FTAG, &origin);
+			if (error != 0) {
+				dsl_dataset_rele(ds, FTAG);
+				return (error);
+			}
+			if (!origin->ds_is_snapshot) {
+				dsl_dataset_rele(origin, FTAG);
+				dsl_dataset_rele(ds, FTAG);
+				return (SET_ERROR(EINVAL));
+			}
+			if (dsl_dataset_phys(origin)->ds_guid != fromguid &&
+			    fromguid != 0) {
+				dsl_dataset_rele(origin, FTAG);
+				dsl_dataset_rele(ds, FTAG);
+				return (SET_ERROR(ENODEV));
+			}
+			dsl_dataset_rele(origin, FTAG);
+		}
+		dsl_dataset_rele(ds, FTAG);
+		error = 0;
+	}
+	return (error);
+}
+
+static void
+dmu_recv_begin_sync(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_begin_arg_t *drba = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+	objset_t *mos = dp->dp_meta_objset;
+	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
+	const char *tofs = drba->drba_cookie->drc_tofs;
+	dsl_dataset_t *ds, *newds;
+	uint64_t dsobj;
+	int error;
+	uint64_t crflags = 0;
+
+	if (drrb->drr_flags & DRR_FLAG_CI_DATA)
+		crflags |= DS_FLAG_CI_DATASET;
+
+	error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
+	if (error == 0) {
+		/* create temporary clone */
+		dsl_dataset_t *snap = NULL;
+		if (drba->drba_snapobj != 0) {
+			VERIFY0(dsl_dataset_hold_obj(dp,
+			    drba->drba_snapobj, FTAG, &snap));
+		}
+		dsobj = dsl_dataset_create_sync(ds->ds_dir, recv_clone_name,
+		    snap, crflags, drba->drba_cred, tx);
+		if (drba->drba_snapobj != 0)
+			dsl_dataset_rele(snap, FTAG);
+		dsl_dataset_rele(ds, FTAG);
+	} else {
+		dsl_dir_t *dd;
+		const char *tail;
+		dsl_dataset_t *origin = NULL;
+
+		VERIFY0(dsl_dir_hold(dp, tofs, FTAG, &dd, &tail));
+
+		if (drba->drba_origin != NULL) {
+			VERIFY0(dsl_dataset_hold(dp, drba->drba_origin,
+			    FTAG, &origin));
+		}
+
+		/* Create new dataset. */
+		dsobj = dsl_dataset_create_sync(dd,
+		    strrchr(tofs, '/') + 1,
+		    origin, crflags, drba->drba_cred, tx);
+		if (origin != NULL)
+			dsl_dataset_rele(origin, FTAG);
+		dsl_dir_rele(dd, FTAG);
+		drba->drba_cookie->drc_newfs = B_TRUE;
+	}
+	VERIFY0(dsl_dataset_own_obj(dp, dsobj, dmu_recv_tag, &newds));
+
+	if (drba->drba_cookie->drc_resumable) {
+		dsl_dataset_zapify(newds, tx);
+		if (drrb->drr_fromguid != 0) {
+			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_FROMGUID,
+			    8, 1, &drrb->drr_fromguid, tx));
+		}
+		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_TOGUID,
+		    8, 1, &drrb->drr_toguid, tx));
+		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_TONAME,
+		    1, strlen(drrb->drr_toname) + 1, drrb->drr_toname, tx));
+		uint64_t one = 1;
+		uint64_t zero = 0;
+		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_OBJECT,
+		    8, 1, &one, tx));
+		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_OFFSET,
+		    8, 1, &zero, tx));
+		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_BYTES,
+		    8, 1, &zero, tx));
+		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
+		    DMU_BACKUP_FEATURE_LARGE_BLOCKS) {
+			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_LARGEBLOCK,
+			    8, 1, &one, tx));
+		}
+		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
+		    DMU_BACKUP_FEATURE_EMBED_DATA) {
+			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_EMBEDOK,
+			    8, 1, &one, tx));
+		}
+		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
+		    DMU_BACKUP_FEATURE_COMPRESSED) {
+			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_COMPRESSOK,
+			    8, 1, &one, tx));
+		}
+	}
+
+	dmu_buf_will_dirty(newds->ds_dbuf, tx);
+	dsl_dataset_phys(newds)->ds_flags |= DS_FLAG_INCONSISTENT;
+
+	/*
+	 * If we actually created a non-clone, we need to create the
+	 * objset in our new dataset.
+	 */
+	rrw_enter(&newds->ds_bp_rwlock, RW_READER, FTAG);
+	if (BP_IS_HOLE(dsl_dataset_get_blkptr(newds))) {
+		(void) dmu_objset_create_impl(dp->dp_spa,
+		    newds, dsl_dataset_get_blkptr(newds), drrb->drr_type, tx);
+	}
+	rrw_exit(&newds->ds_bp_rwlock, FTAG);
+
+	drba->drba_cookie->drc_ds = newds;
+
+	spa_history_log_internal_ds(newds, "receive", tx, "");
+}
+
+static int
+dmu_recv_resume_begin_check(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_begin_arg_t *drba = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
+	int error;
+	uint64_t featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
+	dsl_dataset_t *ds;
+	const char *tofs = drba->drba_cookie->drc_tofs;
+
+	/* 6 extra bytes for /%recv */
+	char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
+
+	/* already checked */
+	ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
+	ASSERT(featureflags & DMU_BACKUP_FEATURE_RESUMING);
+
+	if (DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
+	    DMU_COMPOUNDSTREAM ||
+	    drrb->drr_type >= DMU_OST_NUMTYPES)
+		return (SET_ERROR(EINVAL));
+
+	/* Verify pool version supports SA if SA_SPILL feature set */
+	if ((featureflags & DMU_BACKUP_FEATURE_SA_SPILL) &&
+	    spa_version(dp->dp_spa) < SPA_VERSION_SA)
+		return (SET_ERROR(ENOTSUP));
+
+	/*
+	 * The receiving code doesn't know how to translate a WRITE_EMBEDDED
+	 * record to a plain WRITE record, so the pool must have the
+	 * EMBEDDED_DATA feature enabled if the stream has WRITE_EMBEDDED
+	 * records.  Same with WRITE_EMBEDDED records that use LZ4 compression.
+	 */
+	if ((featureflags & DMU_BACKUP_FEATURE_EMBED_DATA) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EMBEDDED_DATA))
+		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LZ4) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LZ4_COMPRESS))
+		return (SET_ERROR(ENOTSUP));
+
+	/*
+	 * The receiving code doesn't know how to translate large blocks
+	 * to smaller ones, so the pool must have the LARGE_BLOCKS
+	 * feature enabled if the stream has LARGE_BLOCKS. Same with
+	 * large dnodes.
+	 */
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
+		return (SET_ERROR(ENOTSUP));
+	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
+	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
+		return (SET_ERROR(ENOTSUP));
+
+	(void) snprintf(recvname, sizeof (recvname), "%s/%s",
+	    tofs, recv_clone_name);
+
+	if (dsl_dataset_hold(dp, recvname, FTAG, &ds) != 0) {
+		/* %recv does not exist; continue in tofs */
+		error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
+		if (error != 0)
+			return (error);
+	}
+
+	/* check that ds is marked inconsistent */
+	if (!DS_IS_INCONSISTENT(ds)) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+
+	/* check that there is resuming data, and that the toguid matches */
+	if (!dsl_dataset_is_zapified(ds)) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+	uint64_t val;
+	error = zap_lookup(dp->dp_meta_objset, ds->ds_object,
+	    DS_FIELD_RESUME_TOGUID, sizeof (val), 1, &val);
+	if (error != 0 || drrb->drr_toguid != val) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+
+	/*
+	 * Check if the receive is still running.  If so, it will be owned.
+	 * Note that nothing else can own the dataset (e.g. after the receive
+	 * fails) because it will be marked inconsistent.
+	 */
+	if (dsl_dataset_has_owner(ds)) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EBUSY));
+	}
+
+	/* There should not be any snapshots of this fs yet. */
+	if (ds->ds_prev != NULL && ds->ds_prev->ds_dir == ds->ds_dir) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+
+	/*
+	 * Note: resume point will be checked when we process the first WRITE
+	 * record.
+	 */
+
+	/* check that the origin matches */
+	val = 0;
+	(void) zap_lookup(dp->dp_meta_objset, ds->ds_object,
+	    DS_FIELD_RESUME_FROMGUID, sizeof (val), 1, &val);
+	if (drrb->drr_fromguid != val) {
+		dsl_dataset_rele(ds, FTAG);
+		return (SET_ERROR(EINVAL));
+	}
+
+	dsl_dataset_rele(ds, FTAG);
+	return (0);
+}
+
+static void
+dmu_recv_resume_begin_sync(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_begin_arg_t *drba = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+	const char *tofs = drba->drba_cookie->drc_tofs;
+	dsl_dataset_t *ds;
+	uint64_t dsobj;
+	/* 6 extra bytes for /%recv */
+	char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
+
+	(void) snprintf(recvname, sizeof (recvname), "%s/%s",
+	    tofs, recv_clone_name);
+
+	if (dsl_dataset_hold(dp, recvname, FTAG, &ds) != 0) {
+		/* %recv does not exist; continue in tofs */
+		VERIFY0(dsl_dataset_hold(dp, tofs, FTAG, &ds));
+		drba->drba_cookie->drc_newfs = B_TRUE;
+	}
+
+	/* clear the inconsistent flag so that we can own it */
+	ASSERT(DS_IS_INCONSISTENT(ds));
+	dmu_buf_will_dirty(ds->ds_dbuf, tx);
+	dsl_dataset_phys(ds)->ds_flags &= ~DS_FLAG_INCONSISTENT;
+	dsobj = ds->ds_object;
+	dsl_dataset_rele(ds, FTAG);
+
+	VERIFY0(dsl_dataset_own_obj(dp, dsobj, dmu_recv_tag, &ds));
+
+	dmu_buf_will_dirty(ds->ds_dbuf, tx);
+	dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_INCONSISTENT;
+
+	rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
+	ASSERT(!BP_IS_HOLE(dsl_dataset_get_blkptr(ds)));
+	rrw_exit(&ds->ds_bp_rwlock, FTAG);
+
+	drba->drba_cookie->drc_ds = ds;
+
+	spa_history_log_internal_ds(ds, "resume receive", tx, "");
+}
+
+/*
+ * NB: callers *MUST* call dmu_recv_stream() if dmu_recv_begin()
+ * succeeds; otherwise we will leak the holds on the datasets.
+ */
+int
+dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
+    boolean_t force, boolean_t resumable, char *origin, dmu_recv_cookie_t *drc)
+{
+	dmu_recv_begin_arg_t drba = { 0 };
+
+	bzero(drc, sizeof (dmu_recv_cookie_t));
+	drc->drc_drr_begin = drr_begin;
+	drc->drc_drrb = &drr_begin->drr_u.drr_begin;
+	drc->drc_tosnap = tosnap;
+	drc->drc_tofs = tofs;
+	drc->drc_force = force;
+	drc->drc_resumable = resumable;
+	drc->drc_cred = CRED();
+	drc->drc_clone = (origin != NULL);
+
+	if (drc->drc_drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC)) {
+		drc->drc_byteswap = B_TRUE;
+		(void) fletcher_4_incremental_byteswap(drr_begin,
+		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
+		byteswap_record(drr_begin);
+	} else if (drc->drc_drrb->drr_magic == DMU_BACKUP_MAGIC) {
+		(void) fletcher_4_incremental_native(drr_begin,
+		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
+	} else {
+		return (SET_ERROR(EINVAL));
+	}
+
+	drba.drba_origin = origin;
+	drba.drba_cookie = drc;
+	drba.drba_cred = CRED();
+
+	if (DMU_GET_FEATUREFLAGS(drc->drc_drrb->drr_versioninfo) &
+	    DMU_BACKUP_FEATURE_RESUMING) {
+		return (dsl_sync_task(tofs,
+		    dmu_recv_resume_begin_check, dmu_recv_resume_begin_sync,
+		    &drba, 5, ZFS_SPACE_CHECK_NORMAL));
+	} else  {
+		return (dsl_sync_task(tofs,
+		    dmu_recv_begin_check, dmu_recv_begin_sync,
+		    &drba, 5, ZFS_SPACE_CHECK_NORMAL));
+	}
+}
+
+struct receive_record_arg {
+	dmu_replay_record_t header;
+	void *payload; /* Pointer to a buffer containing the payload */
+	/*
+	 * If the record is a write, pointer to the arc_buf_t containing the
+	 * payload.
+	 */
+	arc_buf_t *write_buf;
+	int payload_size;
+	uint64_t bytes_read; /* bytes read from stream when record created */
+	boolean_t eos_marker; /* Marks the end of the stream */
+	bqueue_node_t node;
+};
+
+struct receive_writer_arg {
+	objset_t *os;
+	boolean_t byteswap;
+	bqueue_t q;
+
+	/*
+	 * These three args are used to signal to the main thread that we're
+	 * done.
+	 */
+	kmutex_t mutex;
+	kcondvar_t cv;
+	boolean_t done;
+
+	int err;
+	/* A map from guid to dataset to help handle dedup'd streams. */
+	avl_tree_t *guid_to_ds_map;
+	boolean_t resumable;
+	uint64_t last_object;
+	uint64_t last_offset;
+	uint64_t max_object; /* highest object ID referenced in stream */
+	uint64_t bytes_read; /* bytes read when current record created */
+};
+
+struct objlist {
+	list_t list; /* List of struct receive_objnode. */
+	/*
+	 * Last object looked up. Used to assert that objects are being looked
+	 * up in ascending order.
+	 */
+	uint64_t last_lookup;
+};
+
+struct receive_objnode {
+	list_node_t node;
+	uint64_t object;
+};
+
+struct receive_arg {
+	objset_t *os;
+	vnode_t *vp; /* The vnode to read the stream from */
+	uint64_t voff; /* The current offset in the stream */
+	uint64_t bytes_read;
+	/*
+	 * A record that has had its payload read in, but hasn't yet been handed
+	 * off to the worker thread.
+	 */
+	struct receive_record_arg *rrd;
+	/* A record that has had its header read in, but not its payload. */
+	struct receive_record_arg *next_rrd;
+	zio_cksum_t cksum;
+	zio_cksum_t prev_cksum;
+	int err;
+	boolean_t byteswap;
+	/* Sorted list of objects not to issue prefetches for. */
+	struct objlist ignore_objlist;
+};
+
+typedef struct guid_map_entry {
+	uint64_t	guid;
+	dsl_dataset_t	*gme_ds;
+	avl_node_t	avlnode;
+} guid_map_entry_t;
+
+static int
+guid_compare(const void *arg1, const void *arg2)
+{
+	const guid_map_entry_t *gmep1 = arg1;
+	const guid_map_entry_t *gmep2 = arg2;
+
+	if (gmep1->guid < gmep2->guid)
+		return (-1);
+	else if (gmep1->guid > gmep2->guid)
+		return (1);
+	return (0);
+}
+
+static void
+free_guid_map_onexit(void *arg)
+{
+	avl_tree_t *ca = arg;
+	void *cookie = NULL;
+	guid_map_entry_t *gmep;
+
+	while ((gmep = avl_destroy_nodes(ca, &cookie)) != NULL) {
+		dsl_dataset_long_rele(gmep->gme_ds, gmep);
+		dsl_dataset_rele(gmep->gme_ds, gmep);
+		kmem_free(gmep, sizeof (guid_map_entry_t));
+	}
+	avl_destroy(ca);
+	kmem_free(ca, sizeof (avl_tree_t));
+}
+
+static int
+receive_read(struct receive_arg *ra, int len, void *buf)
+{
+	int done = 0;
+
+	/*
+	 * The code doesn't rely on this (lengths being multiples of 8).  See
+	 * comment in dump_bytes.
+	 */
+	ASSERT0(len % 8);
+
+	while (done < len) {
+		ssize_t resid;
+
+		ra->err = vn_rdwr(UIO_READ, ra->vp,
+		    (char *)buf + done, len - done,
+		    ra->voff, UIO_SYSSPACE, FAPPEND,
+		    RLIM64_INFINITY, CRED(), &resid);
+
+		if (resid == len - done) {
+			/*
+			 * Note: ECKSUM indicates that the receive
+			 * was interrupted and can potentially be resumed.
+			 */
+			ra->err = SET_ERROR(ECKSUM);
+		}
+		ra->voff += len - done - resid;
+		done = len - resid;
+		if (ra->err != 0)
+			return (ra->err);
+	}
+
+	ra->bytes_read += len;
+
+	ASSERT3U(done, ==, len);
+	return (0);
+}
+
+static void
+byteswap_record(dmu_replay_record_t *drr)
+{
+#define	DO64(X) (drr->drr_u.X = BSWAP_64(drr->drr_u.X))
+#define	DO32(X) (drr->drr_u.X = BSWAP_32(drr->drr_u.X))
+	drr->drr_type = BSWAP_32(drr->drr_type);
+	drr->drr_payloadlen = BSWAP_32(drr->drr_payloadlen);
+
+	switch (drr->drr_type) {
+	case DRR_BEGIN:
+		DO64(drr_begin.drr_magic);
+		DO64(drr_begin.drr_versioninfo);
+		DO64(drr_begin.drr_creation_time);
+		DO32(drr_begin.drr_type);
+		DO32(drr_begin.drr_flags);
+		DO64(drr_begin.drr_toguid);
+		DO64(drr_begin.drr_fromguid);
+		break;
+	case DRR_OBJECT:
+		DO64(drr_object.drr_object);
+		DO32(drr_object.drr_type);
+		DO32(drr_object.drr_bonustype);
+		DO32(drr_object.drr_blksz);
+		DO32(drr_object.drr_bonuslen);
+		DO64(drr_object.drr_toguid);
+		break;
+	case DRR_FREEOBJECTS:
+		DO64(drr_freeobjects.drr_firstobj);
+		DO64(drr_freeobjects.drr_numobjs);
+		DO64(drr_freeobjects.drr_toguid);
+		break;
+	case DRR_WRITE:
+		DO64(drr_write.drr_object);
+		DO32(drr_write.drr_type);
+		DO64(drr_write.drr_offset);
+		DO64(drr_write.drr_logical_size);
+		DO64(drr_write.drr_toguid);
+		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_write.drr_key.ddk_cksum);
+		DO64(drr_write.drr_key.ddk_prop);
+		DO64(drr_write.drr_compressed_size);
+		break;
+	case DRR_WRITE_BYREF:
+		DO64(drr_write_byref.drr_object);
+		DO64(drr_write_byref.drr_offset);
+		DO64(drr_write_byref.drr_length);
+		DO64(drr_write_byref.drr_toguid);
+		DO64(drr_write_byref.drr_refguid);
+		DO64(drr_write_byref.drr_refobject);
+		DO64(drr_write_byref.drr_refoffset);
+		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_write_byref.
+		    drr_key.ddk_cksum);
+		DO64(drr_write_byref.drr_key.ddk_prop);
+		break;
+	case DRR_WRITE_EMBEDDED:
+		DO64(drr_write_embedded.drr_object);
+		DO64(drr_write_embedded.drr_offset);
+		DO64(drr_write_embedded.drr_length);
+		DO64(drr_write_embedded.drr_toguid);
+		DO32(drr_write_embedded.drr_lsize);
+		DO32(drr_write_embedded.drr_psize);
+		break;
+	case DRR_FREE:
+		DO64(drr_free.drr_object);
+		DO64(drr_free.drr_offset);
+		DO64(drr_free.drr_length);
+		DO64(drr_free.drr_toguid);
+		break;
+	case DRR_SPILL:
+		DO64(drr_spill.drr_object);
+		DO64(drr_spill.drr_length);
+		DO64(drr_spill.drr_toguid);
+		break;
+	case DRR_END:
+		DO64(drr_end.drr_toguid);
+		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_end.drr_checksum);
+		break;
+	}
+
+	if (drr->drr_type != DRR_BEGIN) {
+		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_checksum.drr_checksum);
+	}
+
+#undef DO64
+#undef DO32
+}
+
+static inline uint8_t
+deduce_nblkptr(dmu_object_type_t bonus_type, uint64_t bonus_size)
+{
+	if (bonus_type == DMU_OT_SA) {
+		return (1);
+	} else {
+		return (1 +
+		    ((DN_OLD_MAX_BONUSLEN -
+		    MIN(DN_OLD_MAX_BONUSLEN, bonus_size)) >> SPA_BLKPTRSHIFT));
+	}
+}
+
+static void
+save_resume_state(struct receive_writer_arg *rwa,
+    uint64_t object, uint64_t offset, dmu_tx_t *tx)
+{
+	int txgoff = dmu_tx_get_txg(tx) & TXG_MASK;
+
+	if (!rwa->resumable)
+		return;
+
+	/*
+	 * We use ds_resume_bytes[] != 0 to indicate that we need to
+	 * update this on disk, so it must not be 0.
+	 */
+	ASSERT(rwa->bytes_read != 0);
+
+	/*
+	 * We only resume from write records, which have a valid
+	 * (non-meta-dnode) object number.
+	 */
+	ASSERT(object != 0);
+
+	/*
+	 * For resuming to work correctly, we must receive records in order,
+	 * sorted by object,offset.  This is checked by the callers, but
+	 * assert it here for good measure.
+	 */
+	ASSERT3U(object, >=, rwa->os->os_dsl_dataset->ds_resume_object[txgoff]);
+	ASSERT(object != rwa->os->os_dsl_dataset->ds_resume_object[txgoff] ||
+	    offset >= rwa->os->os_dsl_dataset->ds_resume_offset[txgoff]);
+	ASSERT3U(rwa->bytes_read, >=,
+	    rwa->os->os_dsl_dataset->ds_resume_bytes[txgoff]);
+
+	rwa->os->os_dsl_dataset->ds_resume_object[txgoff] = object;
+	rwa->os->os_dsl_dataset->ds_resume_offset[txgoff] = offset;
+	rwa->os->os_dsl_dataset->ds_resume_bytes[txgoff] = rwa->bytes_read;
+}
+
+static int
+receive_object(struct receive_writer_arg *rwa, struct drr_object *drro,
+    void *data)
+{
+	dmu_object_info_t doi;
+	dmu_tx_t *tx;
+	uint64_t object;
+	int err;
+	uint8_t dn_slots = drro->drr_dn_slots != 0 ?
+	    drro->drr_dn_slots : DNODE_MIN_SLOTS;
+
+	if (drro->drr_type == DMU_OT_NONE ||
+	    !DMU_OT_IS_VALID(drro->drr_type) ||
+	    !DMU_OT_IS_VALID(drro->drr_bonustype) ||
+	    drro->drr_checksumtype >= ZIO_CHECKSUM_FUNCTIONS ||
+	    drro->drr_compress >= ZIO_COMPRESS_FUNCTIONS ||
+	    P2PHASE(drro->drr_blksz, SPA_MINBLOCKSIZE) ||
+	    drro->drr_blksz < SPA_MINBLOCKSIZE ||
+	    drro->drr_blksz > spa_maxblocksize(dmu_objset_spa(rwa->os)) ||
+	    drro->drr_bonuslen >
+	    DN_BONUS_SIZE(spa_maxdnodesize(dmu_objset_spa(rwa->os))) ||
+	    dn_slots >
+	    (spa_maxdnodesize(dmu_objset_spa(rwa->os)) >> DNODE_SHIFT)) {
+		return (SET_ERROR(EINVAL));
+	}
+
+	err = dmu_object_info(rwa->os, drro->drr_object, &doi);
+
+	if (err != 0 && err != ENOENT && err != EEXIST)
+		return (SET_ERROR(EINVAL));
+
+	if (drro->drr_object > rwa->max_object)
+		rwa->max_object = drro->drr_object;
+
+	/*
+	 * If we are losing blkptrs or changing the block size this must
+	 * be a new file instance.  We must clear out the previous file
+	 * contents before we can change this type of metadata in the dnode.
+	 */
+	if (err == 0) {
+		int nblkptr;
+
+		object = drro->drr_object;
+
+		nblkptr = deduce_nblkptr(drro->drr_bonustype,
+		    drro->drr_bonuslen);
+
+		if (drro->drr_blksz != doi.doi_data_block_size ||
+		    nblkptr < doi.doi_nblkptr ||
+		    dn_slots != doi.doi_dnodesize >> DNODE_SHIFT) {
+			err = dmu_free_long_range(rwa->os, drro->drr_object,
+			    0, DMU_OBJECT_END);
+			if (err != 0)
+				return (SET_ERROR(EINVAL));
+		}
+	} else if (err == EEXIST) {
+		/*
+		 * The object requested is currently an interior slot of a
+		 * multi-slot dnode. This will be resolved when the next txg
+		 * is synced out, since the send stream will have told us
+		 * to free this slot when we freed the associated dnode
+		 * earlier in the stream.
+		 */
+		txg_wait_synced(dmu_objset_pool(rwa->os), 0);
+		object = drro->drr_object;
+	} else {
+		/* object is free and we are about to allocate a new one */
+		object = DMU_NEW_OBJECT;
+	}
+
+	/*
+	 * If this is a multi-slot dnode there is a chance that this
+	 * object will expand into a slot that is already used by
+	 * another object from the previous snapshot. We must free
+	 * these objects before we attempt to allocate the new dnode.
+	 */
+	if (dn_slots > 1) {
+		boolean_t need_sync = B_FALSE;
+
+		for (uint64_t slot = drro->drr_object + 1;
+		    slot < drro->drr_object + dn_slots;
+		    slot++) {
+			dmu_object_info_t slot_doi;
+
+			err = dmu_object_info(rwa->os, slot, &slot_doi);
+			if (err == ENOENT || err == EEXIST)
+				continue;
+			else if (err != 0)
+				return (err);
+
+			err = dmu_free_long_object(rwa->os, slot);
+
+			if (err != 0)
+				return (err);
+
+			need_sync = B_TRUE;
+		}
+
+		if (need_sync)
+			txg_wait_synced(dmu_objset_pool(rwa->os), 0);
+	}
+
+	tx = dmu_tx_create(rwa->os);
+	dmu_tx_hold_bonus(tx, object);
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err != 0) {
+		dmu_tx_abort(tx);
+		return (err);
+	}
+
+	if (object == DMU_NEW_OBJECT) {
+		/* currently free, want to be allocated */
+		err = dmu_object_claim_dnsize(rwa->os, drro->drr_object,
+		    drro->drr_type, drro->drr_blksz,
+		    drro->drr_bonustype, drro->drr_bonuslen,
+		    dn_slots << DNODE_SHIFT, tx);
+	} else if (drro->drr_type != doi.doi_type ||
+	    drro->drr_blksz != doi.doi_data_block_size ||
+	    drro->drr_bonustype != doi.doi_bonus_type ||
+	    drro->drr_bonuslen != doi.doi_bonus_size ||
+	    drro->drr_dn_slots != (doi.doi_dnodesize >> DNODE_SHIFT)) {
+		/* currently allocated, but with different properties */
+		err = dmu_object_reclaim_dnsize(rwa->os, drro->drr_object,
+		    drro->drr_type, drro->drr_blksz,
+		    drro->drr_bonustype, drro->drr_bonuslen,
+		    drro->drr_dn_slots << DNODE_SHIFT, tx);
+	}
+	if (err != 0) {
+		dmu_tx_commit(tx);
+		return (SET_ERROR(EINVAL));
+	}
+
+	dmu_object_set_checksum(rwa->os, drro->drr_object,
+	    drro->drr_checksumtype, tx);
+	dmu_object_set_compress(rwa->os, drro->drr_object,
+	    drro->drr_compress, tx);
+
+	if (data != NULL) {
+		dmu_buf_t *db;
+
+		VERIFY0(dmu_bonus_hold(rwa->os, drro->drr_object, FTAG, &db));
+		dmu_buf_will_dirty(db, tx);
+
+		ASSERT3U(db->db_size, >=, drro->drr_bonuslen);
+		bcopy(data, db->db_data, drro->drr_bonuslen);
+		if (rwa->byteswap) {
+			dmu_object_byteswap_t byteswap =
+			    DMU_OT_BYTESWAP(drro->drr_bonustype);
+			dmu_ot_byteswap[byteswap].ob_func(db->db_data,
+			    drro->drr_bonuslen);
+		}
+		dmu_buf_rele(db, FTAG);
+	}
+	dmu_tx_commit(tx);
+
+	return (0);
+}
+
+/* ARGSUSED */
+static int
+receive_freeobjects(struct receive_writer_arg *rwa,
+    struct drr_freeobjects *drrfo)
+{
+	uint64_t obj;
+	int next_err = 0;
+
+	if (drrfo->drr_firstobj + drrfo->drr_numobjs < drrfo->drr_firstobj)
+		return (SET_ERROR(EINVAL));
+
+	for (obj = drrfo->drr_firstobj == 0 ? 1 : drrfo->drr_firstobj;
+	    obj < drrfo->drr_firstobj + drrfo->drr_numobjs && next_err == 0;
+	    next_err = dmu_object_next(rwa->os, &obj, FALSE, 0)) {
+		int err;
+
+		err = dmu_object_info(rwa->os, obj, NULL);
+		if (err == ENOENT)
+			continue;
+		else if (err != 0)
+			return (err);
+
+		err = dmu_free_long_object(rwa->os, obj);
+		if (err != 0)
+			return (err);
+
+		if (obj > rwa->max_object)
+			rwa->max_object = obj;
+	}
+	if (next_err != ESRCH)
+		return (next_err);
+	return (0);
+}
+
+static int
+receive_write(struct receive_writer_arg *rwa, struct drr_write *drrw,
+    arc_buf_t *abuf)
+{
+	dmu_tx_t *tx;
+	int err;
+
+	if (drrw->drr_offset + drrw->drr_logical_size < drrw->drr_offset ||
+	    !DMU_OT_IS_VALID(drrw->drr_type))
+		return (SET_ERROR(EINVAL));
+
+	/*
+	 * For resuming to work, records must be in increasing order
+	 * by (object, offset).
+	 */
+	if (drrw->drr_object < rwa->last_object ||
+	    (drrw->drr_object == rwa->last_object &&
+	    drrw->drr_offset < rwa->last_offset)) {
+		return (SET_ERROR(EINVAL));
+	}
+	rwa->last_object = drrw->drr_object;
+	rwa->last_offset = drrw->drr_offset;
+
+	if (rwa->last_object > rwa->max_object)
+		rwa->max_object = rwa->last_object;
+
+	if (dmu_object_info(rwa->os, drrw->drr_object, NULL) != 0)
+		return (SET_ERROR(EINVAL));
+
+	tx = dmu_tx_create(rwa->os);
+
+	dmu_tx_hold_write(tx, drrw->drr_object,
+	    drrw->drr_offset, drrw->drr_logical_size);
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err != 0) {
+		dmu_tx_abort(tx);
+		return (err);
+	}
+	if (rwa->byteswap) {
+		dmu_object_byteswap_t byteswap =
+		    DMU_OT_BYTESWAP(drrw->drr_type);
+		dmu_ot_byteswap[byteswap].ob_func(abuf->b_data,
+		    DRR_WRITE_PAYLOAD_SIZE(drrw));
+	}
+
+	/* use the bonus buf to look up the dnode in dmu_assign_arcbuf */
+	dmu_buf_t *bonus;
+	if (dmu_bonus_hold(rwa->os, drrw->drr_object, FTAG, &bonus) != 0)
+		return (SET_ERROR(EINVAL));
+	dmu_assign_arcbuf(bonus, drrw->drr_offset, abuf, tx);
+
+	/*
+	 * Note: If the receive fails, we want the resume stream to start
+	 * with the same record that we last successfully received (as opposed
+	 * to the next record), so that we can verify that we are
+	 * resuming from the correct location.
+	 */
+	save_resume_state(rwa, drrw->drr_object, drrw->drr_offset, tx);
+	dmu_tx_commit(tx);
+	dmu_buf_rele(bonus, FTAG);
+
+	return (0);
+}
+
+/*
+ * Handle a DRR_WRITE_BYREF record.  This record is used in dedup'ed
+ * streams to refer to a copy of the data that is already on the
+ * system because it came in earlier in the stream.  This function
+ * finds the earlier copy of the data, and uses that copy instead of
+ * data from the stream to fulfill this write.
+ */
+static int
+receive_write_byref(struct receive_writer_arg *rwa,
+    struct drr_write_byref *drrwbr)
+{
+	dmu_tx_t *tx;
+	int err;
+	guid_map_entry_t gmesrch;
+	guid_map_entry_t *gmep;
+	avl_index_t where;
+	objset_t *ref_os = NULL;
+	dmu_buf_t *dbp;
+
+	if (drrwbr->drr_offset + drrwbr->drr_length < drrwbr->drr_offset)
+		return (SET_ERROR(EINVAL));
+
+	/*
+	 * If the GUID of the referenced dataset is different from the
+	 * GUID of the target dataset, find the referenced dataset.
+	 */
+	if (drrwbr->drr_toguid != drrwbr->drr_refguid) {
+		gmesrch.guid = drrwbr->drr_refguid;
+		if ((gmep = avl_find(rwa->guid_to_ds_map, &gmesrch,
+		    &where)) == NULL) {
+			return (SET_ERROR(EINVAL));
+		}
+		if (dmu_objset_from_ds(gmep->gme_ds, &ref_os))
+			return (SET_ERROR(EINVAL));
+	} else {
+		ref_os = rwa->os;
+	}
+
+	if (drrwbr->drr_object > rwa->max_object)
+		rwa->max_object = drrwbr->drr_object;
+
+	err = dmu_buf_hold(ref_os, drrwbr->drr_refobject,
+	    drrwbr->drr_refoffset, FTAG, &dbp, DMU_READ_PREFETCH);
+	if (err != 0)
+		return (err);
+
+	tx = dmu_tx_create(rwa->os);
+
+	dmu_tx_hold_write(tx, drrwbr->drr_object,
+	    drrwbr->drr_offset, drrwbr->drr_length);
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err != 0) {
+		dmu_tx_abort(tx);
+		return (err);
+	}
+	dmu_write(rwa->os, drrwbr->drr_object,
+	    drrwbr->drr_offset, drrwbr->drr_length, dbp->db_data, tx);
+	dmu_buf_rele(dbp, FTAG);
+
+	/* See comment in restore_write. */
+	save_resume_state(rwa, drrwbr->drr_object, drrwbr->drr_offset, tx);
+	dmu_tx_commit(tx);
+	return (0);
+}
+
+static int
+receive_write_embedded(struct receive_writer_arg *rwa,
+    struct drr_write_embedded *drrwe, void *data)
+{
+	dmu_tx_t *tx;
+	int err;
+
+	if (drrwe->drr_offset + drrwe->drr_length < drrwe->drr_offset)
+		return (EINVAL);
+
+	if (drrwe->drr_psize > BPE_PAYLOAD_SIZE)
+		return (EINVAL);
+
+	if (drrwe->drr_etype >= NUM_BP_EMBEDDED_TYPES)
+		return (EINVAL);
+	if (drrwe->drr_compression >= ZIO_COMPRESS_FUNCTIONS)
+		return (EINVAL);
+
+	if (drrwe->drr_object > rwa->max_object)
+		rwa->max_object = drrwe->drr_object;
+
+	tx = dmu_tx_create(rwa->os);
+
+	dmu_tx_hold_write(tx, drrwe->drr_object,
+	    drrwe->drr_offset, drrwe->drr_length);
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err != 0) {
+		dmu_tx_abort(tx);
+		return (err);
+	}
+
+	dmu_write_embedded(rwa->os, drrwe->drr_object,
+	    drrwe->drr_offset, data, drrwe->drr_etype,
+	    drrwe->drr_compression, drrwe->drr_lsize, drrwe->drr_psize,
+	    rwa->byteswap ^ ZFS_HOST_BYTEORDER, tx);
+
+	/* See comment in restore_write. */
+	save_resume_state(rwa, drrwe->drr_object, drrwe->drr_offset, tx);
+	dmu_tx_commit(tx);
+	return (0);
+}
+
+static int
+receive_spill(struct receive_writer_arg *rwa, struct drr_spill *drrs,
+    void *data)
+{
+	dmu_tx_t *tx;
+	dmu_buf_t *db, *db_spill;
+	int err;
+
+	if (drrs->drr_length < SPA_MINBLOCKSIZE ||
+	    drrs->drr_length > spa_maxblocksize(dmu_objset_spa(rwa->os)))
+		return (SET_ERROR(EINVAL));
+
+	if (dmu_object_info(rwa->os, drrs->drr_object, NULL) != 0)
+		return (SET_ERROR(EINVAL));
+
+	if (drrs->drr_object > rwa->max_object)
+		rwa->max_object = drrs->drr_object;
+
+	VERIFY0(dmu_bonus_hold(rwa->os, drrs->drr_object, FTAG, &db));
+	if ((err = dmu_spill_hold_by_bonus(db, FTAG, &db_spill)) != 0) {
+		dmu_buf_rele(db, FTAG);
+		return (err);
+	}
+
+	tx = dmu_tx_create(rwa->os);
+
+	dmu_tx_hold_spill(tx, db->db_object);
+
+	err = dmu_tx_assign(tx, TXG_WAIT);
+	if (err != 0) {
+		dmu_buf_rele(db, FTAG);
+		dmu_buf_rele(db_spill, FTAG);
+		dmu_tx_abort(tx);
+		return (err);
+	}
+	dmu_buf_will_dirty(db_spill, tx);
+
+	if (db_spill->db_size < drrs->drr_length)
+		VERIFY(0 == dbuf_spill_set_blksz(db_spill,
+		    drrs->drr_length, tx));
+	bcopy(data, db_spill->db_data, drrs->drr_length);
+
+	dmu_buf_rele(db, FTAG);
+	dmu_buf_rele(db_spill, FTAG);
+
+	dmu_tx_commit(tx);
+	return (0);
+}
+
+/* ARGSUSED */
+static int
+receive_free(struct receive_writer_arg *rwa, struct drr_free *drrf)
+{
+	int err;
+
+	if (drrf->drr_length != -1ULL &&
+	    drrf->drr_offset + drrf->drr_length < drrf->drr_offset)
+		return (SET_ERROR(EINVAL));
+
+	if (dmu_object_info(rwa->os, drrf->drr_object, NULL) != 0)
+		return (SET_ERROR(EINVAL));
+
+	if (drrf->drr_object > rwa->max_object)
+		rwa->max_object = drrf->drr_object;
+
+	err = dmu_free_long_range(rwa->os, drrf->drr_object,
+	    drrf->drr_offset, drrf->drr_length);
+
+	return (err);
+}
+
+/* used to destroy the drc_ds on error */
+static void
+dmu_recv_cleanup_ds(dmu_recv_cookie_t *drc)
+{
+	if (drc->drc_resumable) {
+		/* wait for our resume state to be written to disk */
+		txg_wait_synced(drc->drc_ds->ds_dir->dd_pool, 0);
+		dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
+	} else {
+		char name[ZFS_MAX_DATASET_NAME_LEN];
+		dsl_dataset_name(drc->drc_ds, name);
+		dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
+		(void) dsl_destroy_head(name);
+	}
+}
+
+static void
+receive_cksum(struct receive_arg *ra, int len, void *buf)
+{
+	if (ra->byteswap) {
+		(void) fletcher_4_incremental_byteswap(buf, len, &ra->cksum);
+	} else {
+		(void) fletcher_4_incremental_native(buf, len, &ra->cksum);
+	}
+}
+
+/*
+ * Read the payload into a buffer of size len, and update the current record's
+ * payload field.
+ * Allocate ra->next_rrd and read the next record's header into
+ * ra->next_rrd->header.
+ * Verify checksum of payload and next record.
+ */
+static int
+receive_read_payload_and_next_header(struct receive_arg *ra, int len, void *buf)
+{
+	int err;
+
+	if (len != 0) {
+		ASSERT3U(len, <=, SPA_MAXBLOCKSIZE);
+		err = receive_read(ra, len, buf);
+		if (err != 0)
+			return (err);
+		receive_cksum(ra, len, buf);
+
+		/* note: rrd is NULL when reading the begin record's payload */
+		if (ra->rrd != NULL) {
+			ra->rrd->payload = buf;
+			ra->rrd->payload_size = len;
+			ra->rrd->bytes_read = ra->bytes_read;
+		}
+	}
+
+	ra->prev_cksum = ra->cksum;
+
+	ra->next_rrd = kmem_zalloc(sizeof (*ra->next_rrd), KM_SLEEP);
+	err = receive_read(ra, sizeof (ra->next_rrd->header),
+	    &ra->next_rrd->header);
+	ra->next_rrd->bytes_read = ra->bytes_read;
+	if (err != 0) {
+		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
+		ra->next_rrd = NULL;
+		return (err);
+	}
+	if (ra->next_rrd->header.drr_type == DRR_BEGIN) {
+		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
+		ra->next_rrd = NULL;
+		return (SET_ERROR(EINVAL));
+	}
+
+	/*
+	 * Note: checksum is of everything up to but not including the
+	 * checksum itself.
+	 */
+	ASSERT3U(offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
+	    ==, sizeof (dmu_replay_record_t) - sizeof (zio_cksum_t));
+	receive_cksum(ra,
+	    offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
+	    &ra->next_rrd->header);
+
+	zio_cksum_t cksum_orig =
+	    ra->next_rrd->header.drr_u.drr_checksum.drr_checksum;
+	zio_cksum_t *cksump =
+	    &ra->next_rrd->header.drr_u.drr_checksum.drr_checksum;
+
+	if (ra->byteswap)
+		byteswap_record(&ra->next_rrd->header);
+
+	if ((!ZIO_CHECKSUM_IS_ZERO(cksump)) &&
+	    !ZIO_CHECKSUM_EQUAL(ra->cksum, *cksump)) {
+		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
+		ra->next_rrd = NULL;
+		return (SET_ERROR(ECKSUM));
+	}
+
+	receive_cksum(ra, sizeof (cksum_orig), &cksum_orig);
+
+	return (0);
+}
+
+static void
+objlist_create(struct objlist *list)
+{
+	list_create(&list->list, sizeof (struct receive_objnode),
+	    offsetof(struct receive_objnode, node));
+	list->last_lookup = 0;
+}
+
+static void
+objlist_destroy(struct objlist *list)
+{
+	for (struct receive_objnode *n = list_remove_head(&list->list);
+	    n != NULL; n = list_remove_head(&list->list)) {
+		kmem_free(n, sizeof (*n));
+	}
+	list_destroy(&list->list);
+}
+
+/*
+ * This function looks through the objlist to see if the specified object number
+ * is contained in the objlist.  In the process, it will remove all object
+ * numbers in the list that are smaller than the specified object number.  Thus,
+ * any lookup of an object number smaller than a previously looked up object
+ * number will always return false; therefore, all lookups should be done in
+ * ascending order.
+ */
+static boolean_t
+objlist_exists(struct objlist *list, uint64_t object)
+{
+	struct receive_objnode *node = list_head(&list->list);
+	ASSERT3U(object, >=, list->last_lookup);
+	list->last_lookup = object;
+	while (node != NULL && node->object < object) {
+		VERIFY3P(node, ==, list_remove_head(&list->list));
+		kmem_free(node, sizeof (*node));
+		node = list_head(&list->list);
+	}
+	return (node != NULL && node->object == object);
+}
+
+/*
+ * The objlist is a list of object numbers stored in ascending order.  However,
+ * the insertion of new object numbers does not seek out the correct location to
+ * store a new object number; instead, it appends it to the list for simplicity.
+ * Thus, any users must take care to only insert new object numbers in ascending
+ * order.
+ */
+static void
+objlist_insert(struct objlist *list, uint64_t object)
+{
+	struct receive_objnode *node = kmem_zalloc(sizeof (*node), KM_SLEEP);
+	node->object = object;
+#ifdef ZFS_DEBUG
+	struct receive_objnode *last_object = list_tail(&list->list);
+	uint64_t last_objnum = (last_object != NULL ? last_object->object : 0);
+	ASSERT3U(node->object, >, last_objnum);
+#endif
+	list_insert_tail(&list->list, node);
+}
+
+/*
+ * Issue the prefetch reads for any necessary indirect blocks.
+ *
+ * We use the object ignore list to tell us whether or not to issue prefetches
+ * for a given object.  We do this for both correctness (in case the blocksize
+ * of an object has changed) and performance (if the object doesn't exist, don't
+ * needlessly try to issue prefetches).  We also trim the list as we go through
+ * the stream to prevent it from growing to an unbounded size.
+ *
+ * The object numbers within will always be in sorted order, and any write
+ * records we see will also be in sorted order, but they're not sorted with
+ * respect to each other (i.e. we can get several object records before
+ * receiving each object's write records).  As a result, once we've reached a
+ * given object number, we can safely remove any reference to lower object
+ * numbers in the ignore list. In practice, we receive up to 32 object records
+ * before receiving write records, so the list can have up to 32 nodes in it.
+ */
+/* ARGSUSED */
+static void
+receive_read_prefetch(struct receive_arg *ra,
+    uint64_t object, uint64_t offset, uint64_t length)
+{
+	if (!objlist_exists(&ra->ignore_objlist, object)) {
+		dmu_prefetch(ra->os, object, 1, offset, length,
+		    ZIO_PRIORITY_SYNC_READ);
+	}
+}
+
+/*
+ * Read records off the stream, issuing any necessary prefetches.
+ */
+static int
+receive_read_record(struct receive_arg *ra)
+{
+	int err;
+
+	switch (ra->rrd->header.drr_type) {
+	case DRR_OBJECT:
+	{
+		struct drr_object *drro = &ra->rrd->header.drr_u.drr_object;
+		uint32_t size = P2ROUNDUP(drro->drr_bonuslen, 8);
+		void *buf = kmem_zalloc(size, KM_SLEEP);
+		dmu_object_info_t doi;
+		err = receive_read_payload_and_next_header(ra, size, buf);
+		if (err != 0) {
+			kmem_free(buf, size);
+			return (err);
+		}
+		err = dmu_object_info(ra->os, drro->drr_object, &doi);
+		/*
+		 * See receive_read_prefetch for an explanation why we're
+		 * storing this object in the ignore_obj_list.
+		 */
+		if (err == ENOENT ||
+		    (err == 0 && doi.doi_data_block_size != drro->drr_blksz)) {
+			objlist_insert(&ra->ignore_objlist, drro->drr_object);
+			err = 0;
+		}
+		return (err);
+	}
+	case DRR_FREEOBJECTS:
+	{
+		err = receive_read_payload_and_next_header(ra, 0, NULL);
+		return (err);
+	}
+	case DRR_WRITE:
+	{
+		struct drr_write *drrw = &ra->rrd->header.drr_u.drr_write;
+		arc_buf_t *abuf;
+		boolean_t is_meta = DMU_OT_IS_METADATA(drrw->drr_type);
+		if (DRR_WRITE_COMPRESSED(drrw)) {
+			ASSERT3U(drrw->drr_compressed_size, >, 0);
+			ASSERT3U(drrw->drr_logical_size, >=,
+			    drrw->drr_compressed_size);
+			ASSERT(!is_meta);
+			abuf = arc_loan_compressed_buf(
+			    dmu_objset_spa(ra->os),
+			    drrw->drr_compressed_size, drrw->drr_logical_size,
+			    drrw->drr_compressiontype);
+		} else {
+			abuf = arc_loan_buf(dmu_objset_spa(ra->os),
+			    is_meta, drrw->drr_logical_size);
+		}
+
+		err = receive_read_payload_and_next_header(ra,
+		    DRR_WRITE_PAYLOAD_SIZE(drrw), abuf->b_data);
+		if (err != 0) {
+			dmu_return_arcbuf(abuf);
+			return (err);
+		}
+		ra->rrd->write_buf = abuf;
+		receive_read_prefetch(ra, drrw->drr_object, drrw->drr_offset,
+		    drrw->drr_logical_size);
+		return (err);
+	}
+	case DRR_WRITE_BYREF:
+	{
+		struct drr_write_byref *drrwb =
+		    &ra->rrd->header.drr_u.drr_write_byref;
+		err = receive_read_payload_and_next_header(ra, 0, NULL);
+		receive_read_prefetch(ra, drrwb->drr_object, drrwb->drr_offset,
+		    drrwb->drr_length);
+		return (err);
+	}
+	case DRR_WRITE_EMBEDDED:
+	{
+		struct drr_write_embedded *drrwe =
+		    &ra->rrd->header.drr_u.drr_write_embedded;
+		uint32_t size = P2ROUNDUP(drrwe->drr_psize, 8);
+		void *buf = kmem_zalloc(size, KM_SLEEP);
+
+		err = receive_read_payload_and_next_header(ra, size, buf);
+		if (err != 0) {
+			kmem_free(buf, size);
+			return (err);
+		}
+
+		receive_read_prefetch(ra, drrwe->drr_object, drrwe->drr_offset,
+		    drrwe->drr_length);
+		return (err);
+	}
+	case DRR_FREE:
+	{
+		/*
+		 * It might be beneficial to prefetch indirect blocks here, but
+		 * we don't really have the data to decide for sure.
+		 */
+		err = receive_read_payload_and_next_header(ra, 0, NULL);
+		return (err);
+	}
+	case DRR_END:
+	{
+		struct drr_end *drre = &ra->rrd->header.drr_u.drr_end;
+		if (!ZIO_CHECKSUM_EQUAL(ra->prev_cksum, drre->drr_checksum))
+			return (SET_ERROR(ECKSUM));
+		return (0);
+	}
+	case DRR_SPILL:
+	{
+		struct drr_spill *drrs = &ra->rrd->header.drr_u.drr_spill;
+		void *buf = kmem_zalloc(drrs->drr_length, KM_SLEEP);
+		err = receive_read_payload_and_next_header(ra, drrs->drr_length,
+		    buf);
+		if (err != 0)
+			kmem_free(buf, drrs->drr_length);
+		return (err);
+	}
+	default:
+		return (SET_ERROR(EINVAL));
+	}
+}
+
+/*
+ * Commit the records to the pool.
+ */
+static int
+receive_process_record(struct receive_writer_arg *rwa,
+    struct receive_record_arg *rrd)
+{
+	int err;
+
+	/* Processing in order, therefore bytes_read should be increasing. */
+	ASSERT3U(rrd->bytes_read, >=, rwa->bytes_read);
+	rwa->bytes_read = rrd->bytes_read;
+
+	switch (rrd->header.drr_type) {
+	case DRR_OBJECT:
+	{
+		struct drr_object *drro = &rrd->header.drr_u.drr_object;
+		err = receive_object(rwa, drro, rrd->payload);
+		kmem_free(rrd->payload, rrd->payload_size);
+		rrd->payload = NULL;
+		return (err);
+	}
+	case DRR_FREEOBJECTS:
+	{
+		struct drr_freeobjects *drrfo =
+		    &rrd->header.drr_u.drr_freeobjects;
+		return (receive_freeobjects(rwa, drrfo));
+	}
+	case DRR_WRITE:
+	{
+		struct drr_write *drrw = &rrd->header.drr_u.drr_write;
+		err = receive_write(rwa, drrw, rrd->write_buf);
+		/* if receive_write() is successful, it consumes the arc_buf */
+		if (err != 0)
+			dmu_return_arcbuf(rrd->write_buf);
+		rrd->write_buf = NULL;
+		rrd->payload = NULL;
+		return (err);
+	}
+	case DRR_WRITE_BYREF:
+	{
+		struct drr_write_byref *drrwbr =
+		    &rrd->header.drr_u.drr_write_byref;
+		return (receive_write_byref(rwa, drrwbr));
+	}
+	case DRR_WRITE_EMBEDDED:
+	{
+		struct drr_write_embedded *drrwe =
+		    &rrd->header.drr_u.drr_write_embedded;
+		err = receive_write_embedded(rwa, drrwe, rrd->payload);
+		kmem_free(rrd->payload, rrd->payload_size);
+		rrd->payload = NULL;
+		return (err);
+	}
+	case DRR_FREE:
+	{
+		struct drr_free *drrf = &rrd->header.drr_u.drr_free;
+		return (receive_free(rwa, drrf));
+	}
+	case DRR_SPILL:
+	{
+		struct drr_spill *drrs = &rrd->header.drr_u.drr_spill;
+		err = receive_spill(rwa, drrs, rrd->payload);
+		kmem_free(rrd->payload, rrd->payload_size);
+		rrd->payload = NULL;
+		return (err);
+	}
+	default:
+		return (SET_ERROR(EINVAL));
+	}
+}
+
+/*
+ * dmu_recv_stream's worker thread; pull records off the queue, and then call
+ * receive_process_record  When we're done, signal the main thread and exit.
+ */
+static void
+receive_writer_thread(void *arg)
+{
+	struct receive_writer_arg *rwa = arg;
+	struct receive_record_arg *rrd;
+	for (rrd = bqueue_dequeue(&rwa->q); !rrd->eos_marker;
+	    rrd = bqueue_dequeue(&rwa->q)) {
+		/*
+		 * If there's an error, the main thread will stop putting things
+		 * on the queue, but we need to clear everything in it before we
+		 * can exit.
+		 */
+		if (rwa->err == 0) {
+			rwa->err = receive_process_record(rwa, rrd);
+		} else if (rrd->write_buf != NULL) {
+			dmu_return_arcbuf(rrd->write_buf);
+			rrd->write_buf = NULL;
+			rrd->payload = NULL;
+		} else if (rrd->payload != NULL) {
+			kmem_free(rrd->payload, rrd->payload_size);
+			rrd->payload = NULL;
+		}
+		kmem_free(rrd, sizeof (*rrd));
+	}
+	kmem_free(rrd, sizeof (*rrd));
+	mutex_enter(&rwa->mutex);
+	rwa->done = B_TRUE;
+	cv_signal(&rwa->cv);
+	mutex_exit(&rwa->mutex);
+	thread_exit();
+}
+
+static int
+resume_check(struct receive_arg *ra, nvlist_t *begin_nvl)
+{
+	uint64_t val;
+	objset_t *mos = dmu_objset_pool(ra->os)->dp_meta_objset;
+	uint64_t dsobj = dmu_objset_id(ra->os);
+	uint64_t resume_obj, resume_off;
+
+	if (nvlist_lookup_uint64(begin_nvl,
+	    "resume_object", &resume_obj) != 0 ||
+	    nvlist_lookup_uint64(begin_nvl,
+	    "resume_offset", &resume_off) != 0) {
+		return (SET_ERROR(EINVAL));
+	}
+	VERIFY0(zap_lookup(mos, dsobj,
+	    DS_FIELD_RESUME_OBJECT, sizeof (val), 1, &val));
+	if (resume_obj != val)
+		return (SET_ERROR(EINVAL));
+	VERIFY0(zap_lookup(mos, dsobj,
+	    DS_FIELD_RESUME_OFFSET, sizeof (val), 1, &val));
+	if (resume_off != val)
+		return (SET_ERROR(EINVAL));
+
+	return (0);
+}
+
+/*
+ * Read in the stream's records, one by one, and apply them to the pool.  There
+ * are two threads involved; the thread that calls this function will spin up a
+ * worker thread, read the records off the stream one by one, and issue
+ * prefetches for any necessary indirect blocks.  It will then push the records
+ * onto an internal blocking queue.  The worker thread will pull the records off
+ * the queue, and actually write the data into the DMU.  This way, the worker
+ * thread doesn't have to wait for reads to complete, since everything it needs
+ * (the indirect blocks) will be prefetched.
+ *
+ * NB: callers *must* call dmu_recv_end() if this succeeds.
+ */
+int
+dmu_recv_stream(dmu_recv_cookie_t *drc, vnode_t *vp, offset_t *voffp,
+    int cleanup_fd, uint64_t *action_handlep)
+{
+	int err = 0;
+	struct receive_arg ra = { 0 };
+	struct receive_writer_arg rwa = { 0 };
+	int featureflags;
+	nvlist_t *begin_nvl = NULL;
+
+	ra.byteswap = drc->drc_byteswap;
+	ra.cksum = drc->drc_cksum;
+	ra.vp = vp;
+	ra.voff = *voffp;
+
+	if (dsl_dataset_is_zapified(drc->drc_ds)) {
+		(void) zap_lookup(drc->drc_ds->ds_dir->dd_pool->dp_meta_objset,
+		    drc->drc_ds->ds_object, DS_FIELD_RESUME_BYTES,
+		    sizeof (ra.bytes_read), 1, &ra.bytes_read);
+	}
+
+	objlist_create(&ra.ignore_objlist);
+
+	/* these were verified in dmu_recv_begin */
+	ASSERT3U(DMU_GET_STREAM_HDRTYPE(drc->drc_drrb->drr_versioninfo), ==,
+	    DMU_SUBSTREAM);
+	ASSERT3U(drc->drc_drrb->drr_type, <, DMU_OST_NUMTYPES);
+
+	/*
+	 * Open the objset we are modifying.
+	 */
+	VERIFY0(dmu_objset_from_ds(drc->drc_ds, &ra.os));
+
+	ASSERT(dsl_dataset_phys(drc->drc_ds)->ds_flags & DS_FLAG_INCONSISTENT);
+
+	featureflags = DMU_GET_FEATUREFLAGS(drc->drc_drrb->drr_versioninfo);
+
+	/* if this stream is dedup'ed, set up the avl tree for guid mapping */
+	if (featureflags & DMU_BACKUP_FEATURE_DEDUP) {
+		minor_t minor;
+
+		if (cleanup_fd == -1) {
+			ra.err = SET_ERROR(EBADF);
+			goto out;
+		}
+		ra.err = zfs_onexit_fd_hold(cleanup_fd, &minor);
+		if (ra.err != 0) {
+			cleanup_fd = -1;
+			goto out;
+		}
+
+		if (*action_handlep == 0) {
+			rwa.guid_to_ds_map =
+			    kmem_alloc(sizeof (avl_tree_t), KM_SLEEP);
+			avl_create(rwa.guid_to_ds_map, guid_compare,
+			    sizeof (guid_map_entry_t),
+			    offsetof(guid_map_entry_t, avlnode));
+			err = zfs_onexit_add_cb(minor,
+			    free_guid_map_onexit, rwa.guid_to_ds_map,
+			    action_handlep);
+			if (ra.err != 0)
+				goto out;
+		} else {
+			err = zfs_onexit_cb_data(minor, *action_handlep,
+			    (void **)&rwa.guid_to_ds_map);
+			if (ra.err != 0)
+				goto out;
+		}
+
+		drc->drc_guid_to_ds_map = rwa.guid_to_ds_map;
+	}
+
+	uint32_t payloadlen = drc->drc_drr_begin->drr_payloadlen;
+	void *payload = NULL;
+	if (payloadlen != 0)
+		payload = kmem_alloc(payloadlen, KM_SLEEP);
+
+	err = receive_read_payload_and_next_header(&ra, payloadlen, payload);
+	if (err != 0) {
+		if (payloadlen != 0)
+			kmem_free(payload, payloadlen);
+		goto out;
+	}
+	if (payloadlen != 0) {
+		err = nvlist_unpack(payload, payloadlen, &begin_nvl, KM_SLEEP);
+		kmem_free(payload, payloadlen);
+		if (err != 0)
+			goto out;
+	}
+
+	if (featureflags & DMU_BACKUP_FEATURE_RESUMING) {
+		err = resume_check(&ra, begin_nvl);
+		if (err != 0)
+			goto out;
+	}
+
+	(void) bqueue_init(&rwa.q, zfs_recv_queue_length,
+	    offsetof(struct receive_record_arg, node));
+	cv_init(&rwa.cv, NULL, CV_DEFAULT, NULL);
+	mutex_init(&rwa.mutex, NULL, MUTEX_DEFAULT, NULL);
+	rwa.os = ra.os;
+	rwa.byteswap = drc->drc_byteswap;
+	rwa.resumable = drc->drc_resumable;
+
+	(void) thread_create(NULL, 0, receive_writer_thread, &rwa, 0, curproc,
+	    TS_RUN, minclsyspri);
+	/*
+	 * We're reading rwa.err without locks, which is safe since we are the
+	 * only reader, and the worker thread is the only writer.  It's ok if we
+	 * miss a write for an iteration or two of the loop, since the writer
+	 * thread will keep freeing records we send it until we send it an eos
+	 * marker.
+	 *
+	 * We can leave this loop in 3 ways:  First, if rwa.err is
+	 * non-zero.  In that case, the writer thread will free the rrd we just
+	 * pushed.  Second, if  we're interrupted; in that case, either it's the
+	 * first loop and ra.rrd was never allocated, or it's later, and ra.rrd
+	 * has been handed off to the writer thread who will free it.  Finally,
+	 * if receive_read_record fails or we're at the end of the stream, then
+	 * we free ra.rrd and exit.
+	 */
+	while (rwa.err == 0) {
+		if (issig(JUSTLOOKING) && issig(FORREAL)) {
+			err = SET_ERROR(EINTR);
+			break;
+		}
+
+		ASSERT3P(ra.rrd, ==, NULL);
+		ra.rrd = ra.next_rrd;
+		ra.next_rrd = NULL;
+		/* Allocates and loads header into ra.next_rrd */
+		err = receive_read_record(&ra);
+
+		if (ra.rrd->header.drr_type == DRR_END || err != 0) {
+			kmem_free(ra.rrd, sizeof (*ra.rrd));
+			ra.rrd = NULL;
+			break;
+		}
+
+		bqueue_enqueue(&rwa.q, ra.rrd,
+		    sizeof (struct receive_record_arg) + ra.rrd->payload_size);
+		ra.rrd = NULL;
+	}
+	if (ra.next_rrd == NULL)
+		ra.next_rrd = kmem_zalloc(sizeof (*ra.next_rrd), KM_SLEEP);
+	ra.next_rrd->eos_marker = B_TRUE;
+	bqueue_enqueue(&rwa.q, ra.next_rrd, 1);
+
+	mutex_enter(&rwa.mutex);
+	while (!rwa.done) {
+		cv_wait(&rwa.cv, &rwa.mutex);
+	}
+	mutex_exit(&rwa.mutex);
+
+	/*
+	 * If we are receiving a full stream as a clone, all object IDs which
+	 * are greater than the maximum ID referenced in the stream are
+	 * by definition unused and must be freed. Note that it's possible that
+	 * we've resumed this send and the first record we received was the END
+	 * record. In that case, max_object would be 0, but we shouldn't start
+	 * freeing all objects from there; instead we should start from the
+	 * resumeobj.
+	 */
+	if (drc->drc_clone && drc->drc_drrb->drr_fromguid == 0) {
+		uint64_t obj;
+		if (nvlist_lookup_uint64(begin_nvl, "resume_object", &obj) != 0)
+			obj = 0;
+		if (rwa.max_object > obj)
+			obj = rwa.max_object;
+		obj++;
+		int free_err = 0;
+		int next_err = 0;
+
+		while (next_err == 0) {
+			free_err = dmu_free_long_object(rwa.os, obj);
+			if (free_err != 0 && free_err != ENOENT)
+				break;
+
+			next_err = dmu_object_next(rwa.os, &obj, FALSE, 0);
+		}
+
+		if (err == 0) {
+			if (free_err != 0 && free_err != ENOENT)
+				err = free_err;
+			else if (next_err != ESRCH)
+				err = next_err;
+		}
+	}
+
+	cv_destroy(&rwa.cv);
+	mutex_destroy(&rwa.mutex);
+	bqueue_destroy(&rwa.q);
+	if (err == 0)
+		err = rwa.err;
+
+out:
+	nvlist_free(begin_nvl);
+	if ((featureflags & DMU_BACKUP_FEATURE_DEDUP) && (cleanup_fd != -1))
+		zfs_onexit_fd_rele(cleanup_fd);
+
+	if (err != 0) {
+		/*
+		 * Clean up references. If receive is not resumable,
+		 * destroy what we created, so we don't leave it in
+		 * the inconsistent state.
+		 */
+		dmu_recv_cleanup_ds(drc);
+	}
+
+	*voffp = ra.voff;
+	objlist_destroy(&ra.ignore_objlist);
+	return (err);
+}
+
+static int
+dmu_recv_end_check(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_cookie_t *drc = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+	int error;
+
+	ASSERT3P(drc->drc_ds->ds_owner, ==, dmu_recv_tag);
+
+	if (!drc->drc_newfs) {
+		dsl_dataset_t *origin_head;
+
+		error = dsl_dataset_hold(dp, drc->drc_tofs, FTAG, &origin_head);
+		if (error != 0)
+			return (error);
+		if (drc->drc_force) {
+			/*
+			 * We will destroy any snapshots in tofs (i.e. before
+			 * origin_head) that are after the origin (which is
+			 * the snap before drc_ds, because drc_ds can not
+			 * have any snaps of its own).
+			 */
+			uint64_t obj;
+
+			obj = dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
+			while (obj !=
+			    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj) {
+				dsl_dataset_t *snap;
+				error = dsl_dataset_hold_obj(dp, obj, FTAG,
+				    &snap);
+				if (error != 0)
+					break;
+				if (snap->ds_dir != origin_head->ds_dir)
+					error = SET_ERROR(EINVAL);
+				if (error == 0)  {
+					error = dsl_destroy_snapshot_check_impl(
+					    snap, B_FALSE);
+				}
+				obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
+				dsl_dataset_rele(snap, FTAG);
+				if (error != 0)
+					break;
+			}
+			if (error != 0) {
+				dsl_dataset_rele(origin_head, FTAG);
+				return (error);
+			}
+		}
+		error = dsl_dataset_clone_swap_check_impl(drc->drc_ds,
+		    origin_head, drc->drc_force, drc->drc_owner, tx);
+		if (error != 0) {
+			dsl_dataset_rele(origin_head, FTAG);
+			return (error);
+		}
+		error = dsl_dataset_snapshot_check_impl(origin_head,
+		    drc->drc_tosnap, tx, B_TRUE, 1, drc->drc_cred);
+		dsl_dataset_rele(origin_head, FTAG);
+		if (error != 0)
+			return (error);
+
+		error = dsl_destroy_head_check_impl(drc->drc_ds, 1);
+	} else {
+		error = dsl_dataset_snapshot_check_impl(drc->drc_ds,
+		    drc->drc_tosnap, tx, B_TRUE, 1, drc->drc_cred);
+	}
+	return (error);
+}
+
+static void
+dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
+{
+	dmu_recv_cookie_t *drc = arg;
+	dsl_pool_t *dp = dmu_tx_pool(tx);
+
+	spa_history_log_internal_ds(drc->drc_ds, "finish receiving",
+	    tx, "snap=%s", drc->drc_tosnap);
+
+	if (!drc->drc_newfs) {
+		dsl_dataset_t *origin_head;
+
+		VERIFY0(dsl_dataset_hold(dp, drc->drc_tofs, FTAG,
+		    &origin_head));
+
+		if (drc->drc_force) {
+			/*
+			 * Destroy any snapshots of drc_tofs (origin_head)
+			 * after the origin (the snap before drc_ds).
+			 */
+			uint64_t obj;
+
+			obj = dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
+			while (obj !=
+			    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj) {
+				dsl_dataset_t *snap;
+				VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG,
+				    &snap));
+				ASSERT3P(snap->ds_dir, ==, origin_head->ds_dir);
+				obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
+				dsl_destroy_snapshot_sync_impl(snap,
+				    B_FALSE, tx);
+				dsl_dataset_rele(snap, FTAG);
+			}
+		}
+		VERIFY3P(drc->drc_ds->ds_prev, ==,
+		    origin_head->ds_prev);
+
+		dsl_dataset_clone_swap_sync_impl(drc->drc_ds,
+		    origin_head, tx);
+		dsl_dataset_snapshot_sync_impl(origin_head,
+		    drc->drc_tosnap, tx);
+
+		/* set snapshot's creation time and guid */
+		dmu_buf_will_dirty(origin_head->ds_prev->ds_dbuf, tx);
+		dsl_dataset_phys(origin_head->ds_prev)->ds_creation_time =
+		    drc->drc_drrb->drr_creation_time;
+		dsl_dataset_phys(origin_head->ds_prev)->ds_guid =
+		    drc->drc_drrb->drr_toguid;
+		dsl_dataset_phys(origin_head->ds_prev)->ds_flags &=
+		    ~DS_FLAG_INCONSISTENT;
+
+		dmu_buf_will_dirty(origin_head->ds_dbuf, tx);
+		dsl_dataset_phys(origin_head)->ds_flags &=
+		    ~DS_FLAG_INCONSISTENT;
+
+		drc->drc_newsnapobj =
+		    dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
+
+		dsl_dataset_rele(origin_head, FTAG);
+		dsl_destroy_head_sync_impl(drc->drc_ds, tx);
+
+		if (drc->drc_owner != NULL)
+			VERIFY3P(origin_head->ds_owner, ==, drc->drc_owner);
+	} else {
+		dsl_dataset_t *ds = drc->drc_ds;
+
+		dsl_dataset_snapshot_sync_impl(ds, drc->drc_tosnap, tx);
+
+		/* set snapshot's creation time and guid */
+		dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
+		dsl_dataset_phys(ds->ds_prev)->ds_creation_time =
+		    drc->drc_drrb->drr_creation_time;
+		dsl_dataset_phys(ds->ds_prev)->ds_guid =
+		    drc->drc_drrb->drr_toguid;
+		dsl_dataset_phys(ds->ds_prev)->ds_flags &=
+		    ~DS_FLAG_INCONSISTENT;
+
+		dmu_buf_will_dirty(ds->ds_dbuf, tx);
+		dsl_dataset_phys(ds)->ds_flags &= ~DS_FLAG_INCONSISTENT;
+		if (dsl_dataset_has_resume_receive_state(ds)) {
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_FROMGUID, tx);
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_OBJECT, tx);
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_OFFSET, tx);
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_BYTES, tx);
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_TOGUID, tx);
+			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
+			    DS_FIELD_RESUME_TONAME, tx);
+		}
+		drc->drc_newsnapobj =
+		    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj;
+	}
+	/*
+	 * Release the hold from dmu_recv_begin.  This must be done before
+	 * we return to open context, so that when we free the dataset's dnode,
+	 * we can evict its bonus buffer.
+	 */
+	dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
+	drc->drc_ds = NULL;
+}
+
+static int
+add_ds_to_guidmap(const char *name, avl_tree_t *guid_map, uint64_t snapobj)
+{
+	dsl_pool_t *dp;
+	dsl_dataset_t *snapds;
+	guid_map_entry_t *gmep;
+	int err;
+
+	ASSERT(guid_map != NULL);
+
+	err = dsl_pool_hold(name, FTAG, &dp);
+	if (err != 0)
+		return (err);
+	gmep = kmem_alloc(sizeof (*gmep), KM_SLEEP);
+	err = dsl_dataset_hold_obj(dp, snapobj, gmep, &snapds);
+	if (err == 0) {
+		gmep->guid = dsl_dataset_phys(snapds)->ds_guid;
+		gmep->gme_ds = snapds;
+		avl_add(guid_map, gmep);
+		dsl_dataset_long_hold(snapds, gmep);
+	} else {
+		kmem_free(gmep, sizeof (*gmep));
+	}
+
+	dsl_pool_rele(dp, FTAG);
+	return (err);
+}
+
+static int dmu_recv_end_modified_blocks = 3;
+
+static int
+dmu_recv_existing_end(dmu_recv_cookie_t *drc)
+{
+#ifdef _KERNEL
+	/*
+	 * We will be destroying the ds; make sure its origin is unmounted if
+	 * necessary.
+	 */
+	char name[ZFS_MAX_DATASET_NAME_LEN];
+	dsl_dataset_name(drc->drc_ds, name);
+	zfs_destroy_unmount_origin(name);
+#endif
+
+	return (dsl_sync_task(drc->drc_tofs,
+	    dmu_recv_end_check, dmu_recv_end_sync, drc,
+	    dmu_recv_end_modified_blocks, ZFS_SPACE_CHECK_NORMAL));
+}
+
+static int
+dmu_recv_new_end(dmu_recv_cookie_t *drc)
+{
+	return (dsl_sync_task(drc->drc_tofs,
+	    dmu_recv_end_check, dmu_recv_end_sync, drc,
+	    dmu_recv_end_modified_blocks, ZFS_SPACE_CHECK_NORMAL));
+}
+
+int
+dmu_recv_end(dmu_recv_cookie_t *drc, void *owner)
+{
+	int error;
+
+	drc->drc_owner = owner;
+
+	if (drc->drc_newfs)
+		error = dmu_recv_new_end(drc);
+	else
+		error = dmu_recv_existing_end(drc);
+
+	if (error != 0) {
+		dmu_recv_cleanup_ds(drc);
+	} else if (drc->drc_guid_to_ds_map != NULL) {
+		(void) add_ds_to_guidmap(drc->drc_tofs,
+		    drc->drc_guid_to_ds_map,
+		    drc->drc_newsnapobj);
+	}
+	return (error);
+}
+
+/*
+ * Return TRUE if this objset is currently being received into.
+ */
+boolean_t
+dmu_objset_is_receiving(objset_t *os)
+{
+	return (os->os_dsl_dataset != NULL &&
+	    os->os_dsl_dataset->ds_owner == dmu_recv_tag);
+}
diff --git a/usr/src/uts/common/fs/zfs/dmu_send.c b/usr/src/uts/common/fs/zfs/dmu_send.c
index 669435aa05..6d65086079 100644
--- a/usr/src/uts/common/fs/zfs/dmu_send.c
+++ b/usr/src/uts/common/fs/zfs/dmu_send.c
@@ -59,13 +59,9 @@
 /* Set this tunable to TRUE to replace corrupt data with 0x2f5baddb10c */
 int zfs_send_corrupt_data = B_FALSE;
 int zfs_send_queue_length = 16 * 1024 * 1024;
-int zfs_recv_queue_length = 16 * 1024 * 1024;
 /* Set this tunable to FALSE to disable setting of DRR_FLAG_FREERECORDS */
 int zfs_send_set_freerecords_bit = B_TRUE;
 
-static char *dmu_recv_tag = "dmu_recv_tag";
-const char *recv_clone_name = "%recv";
-
 /*
  * Use this to override the recordsize calculation for fast zfs send estimates.
  */
@@ -75,8 +71,6 @@ uint64_t zfs_override_estimate_recordsize = 0;
 	(((uint64_t)datablkszsec) << (SPA_MINBLOCKSHIFT + \
 	(level) * (indblkshift - SPA_BLKPTRSHIFT)))
 
-static void byteswap_record(dmu_replay_record_t *drr);
-
 struct send_thread_arg {
 	bqueue_t	q;
 	dsl_dataset_t	*ds;		/* Dataset to traverse */
@@ -1257,2199 +1251,3 @@ dmu_send_estimate_from_txg(dsl_dataset_t *ds, uint64_t from_txg,
 	    size.compressed, stream_compressed, sizep);
 	return (err);
 }
-
-typedef struct dmu_recv_begin_arg {
-	const char *drba_origin;
-	dmu_recv_cookie_t *drba_cookie;
-	cred_t *drba_cred;
-	uint64_t drba_snapobj;
-} dmu_recv_begin_arg_t;
-
-static int
-recv_begin_check_existing_impl(dmu_recv_begin_arg_t *drba, dsl_dataset_t *ds,
-    uint64_t fromguid)
-{
-	uint64_t val;
-	int error;
-	dsl_pool_t *dp = ds->ds_dir->dd_pool;
-
-	/* temporary clone name must not exist */
-	error = zap_lookup(dp->dp_meta_objset,
-	    dsl_dir_phys(ds->ds_dir)->dd_child_dir_zapobj, recv_clone_name,
-	    8, 1, &val);
-	if (error != ENOENT)
-		return (error == 0 ? EBUSY : error);
-
-	/* new snapshot name must not exist */
-	error = zap_lookup(dp->dp_meta_objset,
-	    dsl_dataset_phys(ds)->ds_snapnames_zapobj,
-	    drba->drba_cookie->drc_tosnap, 8, 1, &val);
-	if (error != ENOENT)
-		return (error == 0 ? EEXIST : error);
-
-	/*
-	 * Check snapshot limit before receiving. We'll recheck again at the
-	 * end, but might as well abort before receiving if we're already over
-	 * the limit.
-	 *
-	 * Note that we do not check the file system limit with
-	 * dsl_dir_fscount_check because the temporary %clones don't count
-	 * against that limit.
-	 */
-	error = dsl_fs_ss_limit_check(ds->ds_dir, 1, ZFS_PROP_SNAPSHOT_LIMIT,
-	    NULL, drba->drba_cred);
-	if (error != 0)
-		return (error);
-
-	if (fromguid != 0) {
-		dsl_dataset_t *snap;
-		uint64_t obj = dsl_dataset_phys(ds)->ds_prev_snap_obj;
-
-		/* Find snapshot in this dir that matches fromguid. */
-		while (obj != 0) {
-			error = dsl_dataset_hold_obj(dp, obj, FTAG,
-			    &snap);
-			if (error != 0)
-				return (SET_ERROR(ENODEV));
-			if (snap->ds_dir != ds->ds_dir) {
-				dsl_dataset_rele(snap, FTAG);
-				return (SET_ERROR(ENODEV));
-			}
-			if (dsl_dataset_phys(snap)->ds_guid == fromguid)
-				break;
-			obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
-			dsl_dataset_rele(snap, FTAG);
-		}
-		if (obj == 0)
-			return (SET_ERROR(ENODEV));
-
-		if (drba->drba_cookie->drc_force) {
-			drba->drba_snapobj = obj;
-		} else {
-			/*
-			 * If we are not forcing, there must be no
-			 * changes since fromsnap.
-			 */
-			if (dsl_dataset_modified_since_snap(ds, snap)) {
-				dsl_dataset_rele(snap, FTAG);
-				return (SET_ERROR(ETXTBSY));
-			}
-			drba->drba_snapobj = ds->ds_prev->ds_object;
-		}
-
-		dsl_dataset_rele(snap, FTAG);
-	} else {
-		/* if full, then must be forced */
-		if (!drba->drba_cookie->drc_force)
-			return (SET_ERROR(EEXIST));
-		/* start from $ORIGIN@$ORIGIN, if supported */
-		drba->drba_snapobj = dp->dp_origin_snap != NULL ?
-		    dp->dp_origin_snap->ds_object : 0;
-	}
-
-	return (0);
-
-}
-
-static int
-dmu_recv_begin_check(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_begin_arg_t *drba = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
-	uint64_t fromguid = drrb->drr_fromguid;
-	int flags = drrb->drr_flags;
-	int error;
-	uint64_t featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
-	dsl_dataset_t *ds;
-	const char *tofs = drba->drba_cookie->drc_tofs;
-
-	/* already checked */
-	ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
-	ASSERT(!(featureflags & DMU_BACKUP_FEATURE_RESUMING));
-
-	if (DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
-	    DMU_COMPOUNDSTREAM ||
-	    drrb->drr_type >= DMU_OST_NUMTYPES ||
-	    ((flags & DRR_FLAG_CLONE) && drba->drba_origin == NULL))
-		return (SET_ERROR(EINVAL));
-
-	/* Verify pool version supports SA if SA_SPILL feature set */
-	if ((featureflags & DMU_BACKUP_FEATURE_SA_SPILL) &&
-	    spa_version(dp->dp_spa) < SPA_VERSION_SA)
-		return (SET_ERROR(ENOTSUP));
-
-	if (drba->drba_cookie->drc_resumable &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EXTENSIBLE_DATASET))
-		return (SET_ERROR(ENOTSUP));
-
-	/*
-	 * The receiving code doesn't know how to translate a WRITE_EMBEDDED
-	 * record to a plain WRITE record, so the pool must have the
-	 * EMBEDDED_DATA feature enabled if the stream has WRITE_EMBEDDED
-	 * records.  Same with WRITE_EMBEDDED records that use LZ4 compression.
-	 */
-	if ((featureflags & DMU_BACKUP_FEATURE_EMBED_DATA) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EMBEDDED_DATA))
-		return (SET_ERROR(ENOTSUP));
-	if ((featureflags & DMU_BACKUP_FEATURE_LZ4) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LZ4_COMPRESS))
-		return (SET_ERROR(ENOTSUP));
-
-	/*
-	 * The receiving code doesn't know how to translate large blocks
-	 * to smaller ones, so the pool must have the LARGE_BLOCKS
-	 * feature enabled if the stream has LARGE_BLOCKS. Same with
-	 * large dnodes.
-	 */
-	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
-		return (SET_ERROR(ENOTSUP));
-	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
-		return (SET_ERROR(ENOTSUP));
-
-	error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
-	if (error == 0) {
-		/* target fs already exists; recv into temp clone */
-
-		/* Can't recv a clone into an existing fs */
-		if (flags & DRR_FLAG_CLONE || drba->drba_origin) {
-			dsl_dataset_rele(ds, FTAG);
-			return (SET_ERROR(EINVAL));
-		}
-
-		error = recv_begin_check_existing_impl(drba, ds, fromguid);
-		dsl_dataset_rele(ds, FTAG);
-	} else if (error == ENOENT) {
-		/* target fs does not exist; must be a full backup or clone */
-		char buf[ZFS_MAX_DATASET_NAME_LEN];
-
-		/*
-		 * If it's a non-clone incremental, we are missing the
-		 * target fs, so fail the recv.
-		 */
-		if (fromguid != 0 && !(flags & DRR_FLAG_CLONE ||
-		    drba->drba_origin))
-			return (SET_ERROR(ENOENT));
-
-		/*
-		 * If we're receiving a full send as a clone, and it doesn't
-		 * contain all the necessary free records and freeobject
-		 * records, reject it.
-		 */
-		if (fromguid == 0 && drba->drba_origin &&
-		    !(flags & DRR_FLAG_FREERECORDS))
-			return (SET_ERROR(EINVAL));
-
-		/* Open the parent of tofs */
-		ASSERT3U(strlen(tofs), <, sizeof (buf));
-		(void) strlcpy(buf, tofs, strrchr(tofs, '/') - tofs + 1);
-		error = dsl_dataset_hold(dp, buf, FTAG, &ds);
-		if (error != 0)
-			return (error);
-
-		/*
-		 * Check filesystem and snapshot limits before receiving. We'll
-		 * recheck snapshot limits again at the end (we create the
-		 * filesystems and increment those counts during begin_sync).
-		 */
-		error = dsl_fs_ss_limit_check(ds->ds_dir, 1,
-		    ZFS_PROP_FILESYSTEM_LIMIT, NULL, drba->drba_cred);
-		if (error != 0) {
-			dsl_dataset_rele(ds, FTAG);
-			return (error);
-		}
-
-		error = dsl_fs_ss_limit_check(ds->ds_dir, 1,
-		    ZFS_PROP_SNAPSHOT_LIMIT, NULL, drba->drba_cred);
-		if (error != 0) {
-			dsl_dataset_rele(ds, FTAG);
-			return (error);
-		}
-
-		if (drba->drba_origin != NULL) {
-			dsl_dataset_t *origin;
-			error = dsl_dataset_hold(dp, drba->drba_origin,
-			    FTAG, &origin);
-			if (error != 0) {
-				dsl_dataset_rele(ds, FTAG);
-				return (error);
-			}
-			if (!origin->ds_is_snapshot) {
-				dsl_dataset_rele(origin, FTAG);
-				dsl_dataset_rele(ds, FTAG);
-				return (SET_ERROR(EINVAL));
-			}
-			if (dsl_dataset_phys(origin)->ds_guid != fromguid &&
-			    fromguid != 0) {
-				dsl_dataset_rele(origin, FTAG);
-				dsl_dataset_rele(ds, FTAG);
-				return (SET_ERROR(ENODEV));
-			}
-			dsl_dataset_rele(origin, FTAG);
-		}
-		dsl_dataset_rele(ds, FTAG);
-		error = 0;
-	}
-	return (error);
-}
-
-static void
-dmu_recv_begin_sync(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_begin_arg_t *drba = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-	objset_t *mos = dp->dp_meta_objset;
-	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
-	const char *tofs = drba->drba_cookie->drc_tofs;
-	dsl_dataset_t *ds, *newds;
-	uint64_t dsobj;
-	int error;
-	uint64_t crflags = 0;
-
-	if (drrb->drr_flags & DRR_FLAG_CI_DATA)
-		crflags |= DS_FLAG_CI_DATASET;
-
-	error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
-	if (error == 0) {
-		/* create temporary clone */
-		dsl_dataset_t *snap = NULL;
-		if (drba->drba_snapobj != 0) {
-			VERIFY0(dsl_dataset_hold_obj(dp,
-			    drba->drba_snapobj, FTAG, &snap));
-		}
-		dsobj = dsl_dataset_create_sync(ds->ds_dir, recv_clone_name,
-		    snap, crflags, drba->drba_cred, tx);
-		if (drba->drba_snapobj != 0)
-			dsl_dataset_rele(snap, FTAG);
-		dsl_dataset_rele(ds, FTAG);
-	} else {
-		dsl_dir_t *dd;
-		const char *tail;
-		dsl_dataset_t *origin = NULL;
-
-		VERIFY0(dsl_dir_hold(dp, tofs, FTAG, &dd, &tail));
-
-		if (drba->drba_origin != NULL) {
-			VERIFY0(dsl_dataset_hold(dp, drba->drba_origin,
-			    FTAG, &origin));
-		}
-
-		/* Create new dataset. */
-		dsobj = dsl_dataset_create_sync(dd,
-		    strrchr(tofs, '/') + 1,
-		    origin, crflags, drba->drba_cred, tx);
-		if (origin != NULL)
-			dsl_dataset_rele(origin, FTAG);
-		dsl_dir_rele(dd, FTAG);
-		drba->drba_cookie->drc_newfs = B_TRUE;
-	}
-	VERIFY0(dsl_dataset_own_obj(dp, dsobj, dmu_recv_tag, &newds));
-
-	if (drba->drba_cookie->drc_resumable) {
-		dsl_dataset_zapify(newds, tx);
-		if (drrb->drr_fromguid != 0) {
-			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_FROMGUID,
-			    8, 1, &drrb->drr_fromguid, tx));
-		}
-		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_TOGUID,
-		    8, 1, &drrb->drr_toguid, tx));
-		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_TONAME,
-		    1, strlen(drrb->drr_toname) + 1, drrb->drr_toname, tx));
-		uint64_t one = 1;
-		uint64_t zero = 0;
-		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_OBJECT,
-		    8, 1, &one, tx));
-		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_OFFSET,
-		    8, 1, &zero, tx));
-		VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_BYTES,
-		    8, 1, &zero, tx));
-		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
-		    DMU_BACKUP_FEATURE_LARGE_BLOCKS) {
-			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_LARGEBLOCK,
-			    8, 1, &one, tx));
-		}
-		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
-		    DMU_BACKUP_FEATURE_EMBED_DATA) {
-			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_EMBEDOK,
-			    8, 1, &one, tx));
-		}
-		if (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
-		    DMU_BACKUP_FEATURE_COMPRESSED) {
-			VERIFY0(zap_add(mos, dsobj, DS_FIELD_RESUME_COMPRESSOK,
-			    8, 1, &one, tx));
-		}
-	}
-
-	dmu_buf_will_dirty(newds->ds_dbuf, tx);
-	dsl_dataset_phys(newds)->ds_flags |= DS_FLAG_INCONSISTENT;
-
-	/*
-	 * If we actually created a non-clone, we need to create the
-	 * objset in our new dataset.
-	 */
-	rrw_enter(&newds->ds_bp_rwlock, RW_READER, FTAG);
-	if (BP_IS_HOLE(dsl_dataset_get_blkptr(newds))) {
-		(void) dmu_objset_create_impl(dp->dp_spa,
-		    newds, dsl_dataset_get_blkptr(newds), drrb->drr_type, tx);
-	}
-	rrw_exit(&newds->ds_bp_rwlock, FTAG);
-
-	drba->drba_cookie->drc_ds = newds;
-
-	spa_history_log_internal_ds(newds, "receive", tx, "");
-}
-
-static int
-dmu_recv_resume_begin_check(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_begin_arg_t *drba = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-	struct drr_begin *drrb = drba->drba_cookie->drc_drrb;
-	int error;
-	uint64_t featureflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
-	dsl_dataset_t *ds;
-	const char *tofs = drba->drba_cookie->drc_tofs;
-
-	/* 6 extra bytes for /%recv */
-	char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
-
-	/* already checked */
-	ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
-	ASSERT(featureflags & DMU_BACKUP_FEATURE_RESUMING);
-
-	if (DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
-	    DMU_COMPOUNDSTREAM ||
-	    drrb->drr_type >= DMU_OST_NUMTYPES)
-		return (SET_ERROR(EINVAL));
-
-	/* Verify pool version supports SA if SA_SPILL feature set */
-	if ((featureflags & DMU_BACKUP_FEATURE_SA_SPILL) &&
-	    spa_version(dp->dp_spa) < SPA_VERSION_SA)
-		return (SET_ERROR(ENOTSUP));
-
-	/*
-	 * The receiving code doesn't know how to translate a WRITE_EMBEDDED
-	 * record to a plain WRITE record, so the pool must have the
-	 * EMBEDDED_DATA feature enabled if the stream has WRITE_EMBEDDED
-	 * records.  Same with WRITE_EMBEDDED records that use LZ4 compression.
-	 */
-	if ((featureflags & DMU_BACKUP_FEATURE_EMBED_DATA) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_EMBEDDED_DATA))
-		return (SET_ERROR(ENOTSUP));
-	if ((featureflags & DMU_BACKUP_FEATURE_LZ4) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LZ4_COMPRESS))
-		return (SET_ERROR(ENOTSUP));
-
-	/*
-	 * The receiving code doesn't know how to translate large blocks
-	 * to smaller ones, so the pool must have the LARGE_BLOCKS
-	 * feature enabled if the stream has LARGE_BLOCKS. Same with
-	 * large dnodes.
-	 */
-	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_BLOCKS) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_BLOCKS))
-		return (SET_ERROR(ENOTSUP));
-	if ((featureflags & DMU_BACKUP_FEATURE_LARGE_DNODE) &&
-	    !spa_feature_is_enabled(dp->dp_spa, SPA_FEATURE_LARGE_DNODE))
-		return (SET_ERROR(ENOTSUP));
-
-	(void) snprintf(recvname, sizeof (recvname), "%s/%s",
-	    tofs, recv_clone_name);
-
-	if (dsl_dataset_hold(dp, recvname, FTAG, &ds) != 0) {
-		/* %recv does not exist; continue in tofs */
-		error = dsl_dataset_hold(dp, tofs, FTAG, &ds);
-		if (error != 0)
-			return (error);
-	}
-
-	/* check that ds is marked inconsistent */
-	if (!DS_IS_INCONSISTENT(ds)) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EINVAL));
-	}
-
-	/* check that there is resuming data, and that the toguid matches */
-	if (!dsl_dataset_is_zapified(ds)) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EINVAL));
-	}
-	uint64_t val;
-	error = zap_lookup(dp->dp_meta_objset, ds->ds_object,
-	    DS_FIELD_RESUME_TOGUID, sizeof (val), 1, &val);
-	if (error != 0 || drrb->drr_toguid != val) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EINVAL));
-	}
-
-	/*
-	 * Check if the receive is still running.  If so, it will be owned.
-	 * Note that nothing else can own the dataset (e.g. after the receive
-	 * fails) because it will be marked inconsistent.
-	 */
-	if (dsl_dataset_has_owner(ds)) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EBUSY));
-	}
-
-	/* There should not be any snapshots of this fs yet. */
-	if (ds->ds_prev != NULL && ds->ds_prev->ds_dir == ds->ds_dir) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EINVAL));
-	}
-
-	/*
-	 * Note: resume point will be checked when we process the first WRITE
-	 * record.
-	 */
-
-	/* check that the origin matches */
-	val = 0;
-	(void) zap_lookup(dp->dp_meta_objset, ds->ds_object,
-	    DS_FIELD_RESUME_FROMGUID, sizeof (val), 1, &val);
-	if (drrb->drr_fromguid != val) {
-		dsl_dataset_rele(ds, FTAG);
-		return (SET_ERROR(EINVAL));
-	}
-
-	dsl_dataset_rele(ds, FTAG);
-	return (0);
-}
-
-static void
-dmu_recv_resume_begin_sync(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_begin_arg_t *drba = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-	const char *tofs = drba->drba_cookie->drc_tofs;
-	dsl_dataset_t *ds;
-	uint64_t dsobj;
-	/* 6 extra bytes for /%recv */
-	char recvname[ZFS_MAX_DATASET_NAME_LEN + 6];
-
-	(void) snprintf(recvname, sizeof (recvname), "%s/%s",
-	    tofs, recv_clone_name);
-
-	if (dsl_dataset_hold(dp, recvname, FTAG, &ds) != 0) {
-		/* %recv does not exist; continue in tofs */
-		VERIFY0(dsl_dataset_hold(dp, tofs, FTAG, &ds));
-		drba->drba_cookie->drc_newfs = B_TRUE;
-	}
-
-	/* clear the inconsistent flag so that we can own it */
-	ASSERT(DS_IS_INCONSISTENT(ds));
-	dmu_buf_will_dirty(ds->ds_dbuf, tx);
-	dsl_dataset_phys(ds)->ds_flags &= ~DS_FLAG_INCONSISTENT;
-	dsobj = ds->ds_object;
-	dsl_dataset_rele(ds, FTAG);
-
-	VERIFY0(dsl_dataset_own_obj(dp, dsobj, dmu_recv_tag, &ds));
-
-	dmu_buf_will_dirty(ds->ds_dbuf, tx);
-	dsl_dataset_phys(ds)->ds_flags |= DS_FLAG_INCONSISTENT;
-
-	rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
-	ASSERT(!BP_IS_HOLE(dsl_dataset_get_blkptr(ds)));
-	rrw_exit(&ds->ds_bp_rwlock, FTAG);
-
-	drba->drba_cookie->drc_ds = ds;
-
-	spa_history_log_internal_ds(ds, "resume receive", tx, "");
-}
-
-/*
- * NB: callers *MUST* call dmu_recv_stream() if dmu_recv_begin()
- * succeeds; otherwise we will leak the holds on the datasets.
- */
-int
-dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
-    boolean_t force, boolean_t resumable, char *origin, dmu_recv_cookie_t *drc)
-{
-	dmu_recv_begin_arg_t drba = { 0 };
-
-	bzero(drc, sizeof (dmu_recv_cookie_t));
-	drc->drc_drr_begin = drr_begin;
-	drc->drc_drrb = &drr_begin->drr_u.drr_begin;
-	drc->drc_tosnap = tosnap;
-	drc->drc_tofs = tofs;
-	drc->drc_force = force;
-	drc->drc_resumable = resumable;
-	drc->drc_cred = CRED();
-	drc->drc_clone = (origin != NULL);
-
-	if (drc->drc_drrb->drr_magic == BSWAP_64(DMU_BACKUP_MAGIC)) {
-		drc->drc_byteswap = B_TRUE;
-		(void) fletcher_4_incremental_byteswap(drr_begin,
-		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
-		byteswap_record(drr_begin);
-	} else if (drc->drc_drrb->drr_magic == DMU_BACKUP_MAGIC) {
-		(void) fletcher_4_incremental_native(drr_begin,
-		    sizeof (dmu_replay_record_t), &drc->drc_cksum);
-	} else {
-		return (SET_ERROR(EINVAL));
-	}
-
-	drba.drba_origin = origin;
-	drba.drba_cookie = drc;
-	drba.drba_cred = CRED();
-
-	if (DMU_GET_FEATUREFLAGS(drc->drc_drrb->drr_versioninfo) &
-	    DMU_BACKUP_FEATURE_RESUMING) {
-		return (dsl_sync_task(tofs,
-		    dmu_recv_resume_begin_check, dmu_recv_resume_begin_sync,
-		    &drba, 5, ZFS_SPACE_CHECK_NORMAL));
-	} else  {
-		return (dsl_sync_task(tofs,
-		    dmu_recv_begin_check, dmu_recv_begin_sync,
-		    &drba, 5, ZFS_SPACE_CHECK_NORMAL));
-	}
-}
-
-struct receive_record_arg {
-	dmu_replay_record_t header;
-	void *payload; /* Pointer to a buffer containing the payload */
-	/*
-	 * If the record is a write, pointer to the arc_buf_t containing the
-	 * payload.
-	 */
-	arc_buf_t *write_buf;
-	int payload_size;
-	uint64_t bytes_read; /* bytes read from stream when record created */
-	boolean_t eos_marker; /* Marks the end of the stream */
-	bqueue_node_t node;
-};
-
-struct receive_writer_arg {
-	objset_t *os;
-	boolean_t byteswap;
-	bqueue_t q;
-
-	/*
-	 * These three args are used to signal to the main thread that we're
-	 * done.
-	 */
-	kmutex_t mutex;
-	kcondvar_t cv;
-	boolean_t done;
-
-	int err;
-	/* A map from guid to dataset to help handle dedup'd streams. */
-	avl_tree_t *guid_to_ds_map;
-	boolean_t resumable;
-	uint64_t last_object;
-	uint64_t last_offset;
-	uint64_t max_object; /* highest object ID referenced in stream */
-	uint64_t bytes_read; /* bytes read when current record created */
-};
-
-struct objlist {
-	list_t list; /* List of struct receive_objnode. */
-	/*
-	 * Last object looked up. Used to assert that objects are being looked
-	 * up in ascending order.
-	 */
-	uint64_t last_lookup;
-};
-
-struct receive_objnode {
-	list_node_t node;
-	uint64_t object;
-};
-
-struct receive_arg {
-	objset_t *os;
-	vnode_t *vp; /* The vnode to read the stream from */
-	uint64_t voff; /* The current offset in the stream */
-	uint64_t bytes_read;
-	/*
-	 * A record that has had its payload read in, but hasn't yet been handed
-	 * off to the worker thread.
-	 */
-	struct receive_record_arg *rrd;
-	/* A record that has had its header read in, but not its payload. */
-	struct receive_record_arg *next_rrd;
-	zio_cksum_t cksum;
-	zio_cksum_t prev_cksum;
-	int err;
-	boolean_t byteswap;
-	/* Sorted list of objects not to issue prefetches for. */
-	struct objlist ignore_objlist;
-};
-
-typedef struct guid_map_entry {
-	uint64_t	guid;
-	dsl_dataset_t	*gme_ds;
-	avl_node_t	avlnode;
-} guid_map_entry_t;
-
-static int
-guid_compare(const void *arg1, const void *arg2)
-{
-	const guid_map_entry_t *gmep1 = arg1;
-	const guid_map_entry_t *gmep2 = arg2;
-
-	if (gmep1->guid < gmep2->guid)
-		return (-1);
-	else if (gmep1->guid > gmep2->guid)
-		return (1);
-	return (0);
-}
-
-static void
-free_guid_map_onexit(void *arg)
-{
-	avl_tree_t *ca = arg;
-	void *cookie = NULL;
-	guid_map_entry_t *gmep;
-
-	while ((gmep = avl_destroy_nodes(ca, &cookie)) != NULL) {
-		dsl_dataset_long_rele(gmep->gme_ds, gmep);
-		dsl_dataset_rele(gmep->gme_ds, gmep);
-		kmem_free(gmep, sizeof (guid_map_entry_t));
-	}
-	avl_destroy(ca);
-	kmem_free(ca, sizeof (avl_tree_t));
-}
-
-static int
-receive_read(struct receive_arg *ra, int len, void *buf)
-{
-	int done = 0;
-
-	/*
-	 * The code doesn't rely on this (lengths being multiples of 8).  See
-	 * comment in dump_bytes.
-	 */
-	ASSERT0(len % 8);
-
-	while (done < len) {
-		ssize_t resid;
-
-		ra->err = vn_rdwr(UIO_READ, ra->vp,
-		    (char *)buf + done, len - done,
-		    ra->voff, UIO_SYSSPACE, FAPPEND,
-		    RLIM64_INFINITY, CRED(), &resid);
-
-		if (resid == len - done) {
-			/*
-			 * Note: ECKSUM indicates that the receive
-			 * was interrupted and can potentially be resumed.
-			 */
-			ra->err = SET_ERROR(ECKSUM);
-		}
-		ra->voff += len - done - resid;
-		done = len - resid;
-		if (ra->err != 0)
-			return (ra->err);
-	}
-
-	ra->bytes_read += len;
-
-	ASSERT3U(done, ==, len);
-	return (0);
-}
-
-static void
-byteswap_record(dmu_replay_record_t *drr)
-{
-#define	DO64(X) (drr->drr_u.X = BSWAP_64(drr->drr_u.X))
-#define	DO32(X) (drr->drr_u.X = BSWAP_32(drr->drr_u.X))
-	drr->drr_type = BSWAP_32(drr->drr_type);
-	drr->drr_payloadlen = BSWAP_32(drr->drr_payloadlen);
-
-	switch (drr->drr_type) {
-	case DRR_BEGIN:
-		DO64(drr_begin.drr_magic);
-		DO64(drr_begin.drr_versioninfo);
-		DO64(drr_begin.drr_creation_time);
-		DO32(drr_begin.drr_type);
-		DO32(drr_begin.drr_flags);
-		DO64(drr_begin.drr_toguid);
-		DO64(drr_begin.drr_fromguid);
-		break;
-	case DRR_OBJECT:
-		DO64(drr_object.drr_object);
-		DO32(drr_object.drr_type);
-		DO32(drr_object.drr_bonustype);
-		DO32(drr_object.drr_blksz);
-		DO32(drr_object.drr_bonuslen);
-		DO64(drr_object.drr_toguid);
-		break;
-	case DRR_FREEOBJECTS:
-		DO64(drr_freeobjects.drr_firstobj);
-		DO64(drr_freeobjects.drr_numobjs);
-		DO64(drr_freeobjects.drr_toguid);
-		break;
-	case DRR_WRITE:
-		DO64(drr_write.drr_object);
-		DO32(drr_write.drr_type);
-		DO64(drr_write.drr_offset);
-		DO64(drr_write.drr_logical_size);
-		DO64(drr_write.drr_toguid);
-		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_write.drr_key.ddk_cksum);
-		DO64(drr_write.drr_key.ddk_prop);
-		DO64(drr_write.drr_compressed_size);
-		break;
-	case DRR_WRITE_BYREF:
-		DO64(drr_write_byref.drr_object);
-		DO64(drr_write_byref.drr_offset);
-		DO64(drr_write_byref.drr_length);
-		DO64(drr_write_byref.drr_toguid);
-		DO64(drr_write_byref.drr_refguid);
-		DO64(drr_write_byref.drr_refobject);
-		DO64(drr_write_byref.drr_refoffset);
-		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_write_byref.
-		    drr_key.ddk_cksum);
-		DO64(drr_write_byref.drr_key.ddk_prop);
-		break;
-	case DRR_WRITE_EMBEDDED:
-		DO64(drr_write_embedded.drr_object);
-		DO64(drr_write_embedded.drr_offset);
-		DO64(drr_write_embedded.drr_length);
-		DO64(drr_write_embedded.drr_toguid);
-		DO32(drr_write_embedded.drr_lsize);
-		DO32(drr_write_embedded.drr_psize);
-		break;
-	case DRR_FREE:
-		DO64(drr_free.drr_object);
-		DO64(drr_free.drr_offset);
-		DO64(drr_free.drr_length);
-		DO64(drr_free.drr_toguid);
-		break;
-	case DRR_SPILL:
-		DO64(drr_spill.drr_object);
-		DO64(drr_spill.drr_length);
-		DO64(drr_spill.drr_toguid);
-		break;
-	case DRR_END:
-		DO64(drr_end.drr_toguid);
-		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_end.drr_checksum);
-		break;
-	}
-
-	if (drr->drr_type != DRR_BEGIN) {
-		ZIO_CHECKSUM_BSWAP(&drr->drr_u.drr_checksum.drr_checksum);
-	}
-
-#undef DO64
-#undef DO32
-}
-
-static inline uint8_t
-deduce_nblkptr(dmu_object_type_t bonus_type, uint64_t bonus_size)
-{
-	if (bonus_type == DMU_OT_SA) {
-		return (1);
-	} else {
-		return (1 +
-		    ((DN_OLD_MAX_BONUSLEN -
-		    MIN(DN_OLD_MAX_BONUSLEN, bonus_size)) >> SPA_BLKPTRSHIFT));
-	}
-}
-
-static void
-save_resume_state(struct receive_writer_arg *rwa,
-    uint64_t object, uint64_t offset, dmu_tx_t *tx)
-{
-	int txgoff = dmu_tx_get_txg(tx) & TXG_MASK;
-
-	if (!rwa->resumable)
-		return;
-
-	/*
-	 * We use ds_resume_bytes[] != 0 to indicate that we need to
-	 * update this on disk, so it must not be 0.
-	 */
-	ASSERT(rwa->bytes_read != 0);
-
-	/*
-	 * We only resume from write records, which have a valid
-	 * (non-meta-dnode) object number.
-	 */
-	ASSERT(object != 0);
-
-	/*
-	 * For resuming to work correctly, we must receive records in order,
-	 * sorted by object,offset.  This is checked by the callers, but
-	 * assert it here for good measure.
-	 */
-	ASSERT3U(object, >=, rwa->os->os_dsl_dataset->ds_resume_object[txgoff]);
-	ASSERT(object != rwa->os->os_dsl_dataset->ds_resume_object[txgoff] ||
-	    offset >= rwa->os->os_dsl_dataset->ds_resume_offset[txgoff]);
-	ASSERT3U(rwa->bytes_read, >=,
-	    rwa->os->os_dsl_dataset->ds_resume_bytes[txgoff]);
-
-	rwa->os->os_dsl_dataset->ds_resume_object[txgoff] = object;
-	rwa->os->os_dsl_dataset->ds_resume_offset[txgoff] = offset;
-	rwa->os->os_dsl_dataset->ds_resume_bytes[txgoff] = rwa->bytes_read;
-}
-
-static int
-receive_object(struct receive_writer_arg *rwa, struct drr_object *drro,
-    void *data)
-{
-	dmu_object_info_t doi;
-	dmu_tx_t *tx;
-	uint64_t object;
-	int err;
-	uint8_t dn_slots = drro->drr_dn_slots != 0 ?
-	    drro->drr_dn_slots : DNODE_MIN_SLOTS;
-
-	if (drro->drr_type == DMU_OT_NONE ||
-	    !DMU_OT_IS_VALID(drro->drr_type) ||
-	    !DMU_OT_IS_VALID(drro->drr_bonustype) ||
-	    drro->drr_checksumtype >= ZIO_CHECKSUM_FUNCTIONS ||
-	    drro->drr_compress >= ZIO_COMPRESS_FUNCTIONS ||
-	    P2PHASE(drro->drr_blksz, SPA_MINBLOCKSIZE) ||
-	    drro->drr_blksz < SPA_MINBLOCKSIZE ||
-	    drro->drr_blksz > spa_maxblocksize(dmu_objset_spa(rwa->os)) ||
-	    drro->drr_bonuslen >
-	    DN_BONUS_SIZE(spa_maxdnodesize(dmu_objset_spa(rwa->os))) ||
-	    dn_slots >
-	    (spa_maxdnodesize(dmu_objset_spa(rwa->os)) >> DNODE_SHIFT)) {
-		return (SET_ERROR(EINVAL));
-	}
-
-	err = dmu_object_info(rwa->os, drro->drr_object, &doi);
-
-	if (err != 0 && err != ENOENT && err != EEXIST)
-		return (SET_ERROR(EINVAL));
-
-	if (drro->drr_object > rwa->max_object)
-		rwa->max_object = drro->drr_object;
-
-	/*
-	 * If we are losing blkptrs or changing the block size this must
-	 * be a new file instance.  We must clear out the previous file
-	 * contents before we can change this type of metadata in the dnode.
-	 */
-	if (err == 0) {
-		int nblkptr;
-
-		object = drro->drr_object;
-
-		nblkptr = deduce_nblkptr(drro->drr_bonustype,
-		    drro->drr_bonuslen);
-
-		if (drro->drr_blksz != doi.doi_data_block_size ||
-		    nblkptr < doi.doi_nblkptr ||
-		    dn_slots != doi.doi_dnodesize >> DNODE_SHIFT) {
-			err = dmu_free_long_range(rwa->os, drro->drr_object,
-			    0, DMU_OBJECT_END);
-			if (err != 0)
-				return (SET_ERROR(EINVAL));
-		}
-	} else if (err == EEXIST) {
-		/*
-		 * The object requested is currently an interior slot of a
-		 * multi-slot dnode. This will be resolved when the next txg
-		 * is synced out, since the send stream will have told us
-		 * to free this slot when we freed the associated dnode
-		 * earlier in the stream.
-		 */
-		txg_wait_synced(dmu_objset_pool(rwa->os), 0);
-		object = drro->drr_object;
-	} else {
-		/* object is free and we are about to allocate a new one */
-		object = DMU_NEW_OBJECT;
-	}
-
-	/*
-	 * If this is a multi-slot dnode there is a chance that this
-	 * object will expand into a slot that is already used by
-	 * another object from the previous snapshot. We must free
-	 * these objects before we attempt to allocate the new dnode.
-	 */
-	if (dn_slots > 1) {
-		boolean_t need_sync = B_FALSE;
-
-		for (uint64_t slot = drro->drr_object + 1;
-		    slot < drro->drr_object + dn_slots;
-		    slot++) {
-			dmu_object_info_t slot_doi;
-
-			err = dmu_object_info(rwa->os, slot, &slot_doi);
-			if (err == ENOENT || err == EEXIST)
-				continue;
-			else if (err != 0)
-				return (err);
-
-			err = dmu_free_long_object(rwa->os, slot);
-
-			if (err != 0)
-				return (err);
-
-			need_sync = B_TRUE;
-		}
-
-		if (need_sync)
-			txg_wait_synced(dmu_objset_pool(rwa->os), 0);
-	}
-
-	tx = dmu_tx_create(rwa->os);
-	dmu_tx_hold_bonus(tx, object);
-	err = dmu_tx_assign(tx, TXG_WAIT);
-	if (err != 0) {
-		dmu_tx_abort(tx);
-		return (err);
-	}
-
-	if (object == DMU_NEW_OBJECT) {
-		/* currently free, want to be allocated */
-		err = dmu_object_claim_dnsize(rwa->os, drro->drr_object,
-		    drro->drr_type, drro->drr_blksz,
-		    drro->drr_bonustype, drro->drr_bonuslen,
-		    dn_slots << DNODE_SHIFT, tx);
-	} else if (drro->drr_type != doi.doi_type ||
-	    drro->drr_blksz != doi.doi_data_block_size ||
-	    drro->drr_bonustype != doi.doi_bonus_type ||
-	    drro->drr_bonuslen != doi.doi_bonus_size ||
-	    drro->drr_dn_slots != (doi.doi_dnodesize >> DNODE_SHIFT)) {
-		/* currently allocated, but with different properties */
-		err = dmu_object_reclaim_dnsize(rwa->os, drro->drr_object,
-		    drro->drr_type, drro->drr_blksz,
-		    drro->drr_bonustype, drro->drr_bonuslen,
-		    drro->drr_dn_slots << DNODE_SHIFT, tx);
-	}
-	if (err != 0) {
-		dmu_tx_commit(tx);
-		return (SET_ERROR(EINVAL));
-	}
-
-	dmu_object_set_checksum(rwa->os, drro->drr_object,
-	    drro->drr_checksumtype, tx);
-	dmu_object_set_compress(rwa->os, drro->drr_object,
-	    drro->drr_compress, tx);
-
-	if (data != NULL) {
-		dmu_buf_t *db;
-
-		VERIFY0(dmu_bonus_hold(rwa->os, drro->drr_object, FTAG, &db));
-		dmu_buf_will_dirty(db, tx);
-
-		ASSERT3U(db->db_size, >=, drro->drr_bonuslen);
-		bcopy(data, db->db_data, drro->drr_bonuslen);
-		if (rwa->byteswap) {
-			dmu_object_byteswap_t byteswap =
-			    DMU_OT_BYTESWAP(drro->drr_bonustype);
-			dmu_ot_byteswap[byteswap].ob_func(db->db_data,
-			    drro->drr_bonuslen);
-		}
-		dmu_buf_rele(db, FTAG);
-	}
-	dmu_tx_commit(tx);
-
-	return (0);
-}
-
-/* ARGSUSED */
-static int
-receive_freeobjects(struct receive_writer_arg *rwa,
-    struct drr_freeobjects *drrfo)
-{
-	uint64_t obj;
-	int next_err = 0;
-
-	if (drrfo->drr_firstobj + drrfo->drr_numobjs < drrfo->drr_firstobj)
-		return (SET_ERROR(EINVAL));
-
-	for (obj = drrfo->drr_firstobj == 0 ? 1 : drrfo->drr_firstobj;
-	    obj < drrfo->drr_firstobj + drrfo->drr_numobjs && next_err == 0;
-	    next_err = dmu_object_next(rwa->os, &obj, FALSE, 0)) {
-		int err;
-
-		err = dmu_object_info(rwa->os, obj, NULL);
-		if (err == ENOENT)
-			continue;
-		else if (err != 0)
-			return (err);
-
-		err = dmu_free_long_object(rwa->os, obj);
-		if (err != 0)
-			return (err);
-
-		if (obj > rwa->max_object)
-			rwa->max_object = obj;
-	}
-	if (next_err != ESRCH)
-		return (next_err);
-	return (0);
-}
-
-static int
-receive_write(struct receive_writer_arg *rwa, struct drr_write *drrw,
-    arc_buf_t *abuf)
-{
-	dmu_tx_t *tx;
-	int err;
-
-	if (drrw->drr_offset + drrw->drr_logical_size < drrw->drr_offset ||
-	    !DMU_OT_IS_VALID(drrw->drr_type))
-		return (SET_ERROR(EINVAL));
-
-	/*
-	 * For resuming to work, records must be in increasing order
-	 * by (object, offset).
-	 */
-	if (drrw->drr_object < rwa->last_object ||
-	    (drrw->drr_object == rwa->last_object &&
-	    drrw->drr_offset < rwa->last_offset)) {
-		return (SET_ERROR(EINVAL));
-	}
-	rwa->last_object = drrw->drr_object;
-	rwa->last_offset = drrw->drr_offset;
-
-	if (rwa->last_object > rwa->max_object)
-		rwa->max_object = rwa->last_object;
-
-	if (dmu_object_info(rwa->os, drrw->drr_object, NULL) != 0)
-		return (SET_ERROR(EINVAL));
-
-	tx = dmu_tx_create(rwa->os);
-
-	dmu_tx_hold_write(tx, drrw->drr_object,
-	    drrw->drr_offset, drrw->drr_logical_size);
-	err = dmu_tx_assign(tx, TXG_WAIT);
-	if (err != 0) {
-		dmu_tx_abort(tx);
-		return (err);
-	}
-	if (rwa->byteswap) {
-		dmu_object_byteswap_t byteswap =
-		    DMU_OT_BYTESWAP(drrw->drr_type);
-		dmu_ot_byteswap[byteswap].ob_func(abuf->b_data,
-		    DRR_WRITE_PAYLOAD_SIZE(drrw));
-	}
-
-	/* use the bonus buf to look up the dnode in dmu_assign_arcbuf */
-	dmu_buf_t *bonus;
-	if (dmu_bonus_hold(rwa->os, drrw->drr_object, FTAG, &bonus) != 0)
-		return (SET_ERROR(EINVAL));
-	dmu_assign_arcbuf(bonus, drrw->drr_offset, abuf, tx);
-
-	/*
-	 * Note: If the receive fails, we want the resume stream to start
-	 * with the same record that we last successfully received (as opposed
-	 * to the next record), so that we can verify that we are
-	 * resuming from the correct location.
-	 */
-	save_resume_state(rwa, drrw->drr_object, drrw->drr_offset, tx);
-	dmu_tx_commit(tx);
-	dmu_buf_rele(bonus, FTAG);
-
-	return (0);
-}
-
-/*
- * Handle a DRR_WRITE_BYREF record.  This record is used in dedup'ed
- * streams to refer to a copy of the data that is already on the
- * system because it came in earlier in the stream.  This function
- * finds the earlier copy of the data, and uses that copy instead of
- * data from the stream to fulfill this write.
- */
-static int
-receive_write_byref(struct receive_writer_arg *rwa,
-    struct drr_write_byref *drrwbr)
-{
-	dmu_tx_t *tx;
-	int err;
-	guid_map_entry_t gmesrch;
-	guid_map_entry_t *gmep;
-	avl_index_t where;
-	objset_t *ref_os = NULL;
-	dmu_buf_t *dbp;
-
-	if (drrwbr->drr_offset + drrwbr->drr_length < drrwbr->drr_offset)
-		return (SET_ERROR(EINVAL));
-
-	/*
-	 * If the GUID of the referenced dataset is different from the
-	 * GUID of the target dataset, find the referenced dataset.
-	 */
-	if (drrwbr->drr_toguid != drrwbr->drr_refguid) {
-		gmesrch.guid = drrwbr->drr_refguid;
-		if ((gmep = avl_find(rwa->guid_to_ds_map, &gmesrch,
-		    &where)) == NULL) {
-			return (SET_ERROR(EINVAL));
-		}
-		if (dmu_objset_from_ds(gmep->gme_ds, &ref_os))
-			return (SET_ERROR(EINVAL));
-	} else {
-		ref_os = rwa->os;
-	}
-
-	if (drrwbr->drr_object > rwa->max_object)
-		rwa->max_object = drrwbr->drr_object;
-
-	err = dmu_buf_hold(ref_os, drrwbr->drr_refobject,
-	    drrwbr->drr_refoffset, FTAG, &dbp, DMU_READ_PREFETCH);
-	if (err != 0)
-		return (err);
-
-	tx = dmu_tx_create(rwa->os);
-
-	dmu_tx_hold_write(tx, drrwbr->drr_object,
-	    drrwbr->drr_offset, drrwbr->drr_length);
-	err = dmu_tx_assign(tx, TXG_WAIT);
-	if (err != 0) {
-		dmu_tx_abort(tx);
-		return (err);
-	}
-	dmu_write(rwa->os, drrwbr->drr_object,
-	    drrwbr->drr_offset, drrwbr->drr_length, dbp->db_data, tx);
-	dmu_buf_rele(dbp, FTAG);
-
-	/* See comment in restore_write. */
-	save_resume_state(rwa, drrwbr->drr_object, drrwbr->drr_offset, tx);
-	dmu_tx_commit(tx);
-	return (0);
-}
-
-static int
-receive_write_embedded(struct receive_writer_arg *rwa,
-    struct drr_write_embedded *drrwe, void *data)
-{
-	dmu_tx_t *tx;
-	int err;
-
-	if (drrwe->drr_offset + drrwe->drr_length < drrwe->drr_offset)
-		return (EINVAL);
-
-	if (drrwe->drr_psize > BPE_PAYLOAD_SIZE)
-		return (EINVAL);
-
-	if (drrwe->drr_etype >= NUM_BP_EMBEDDED_TYPES)
-		return (EINVAL);
-	if (drrwe->drr_compression >= ZIO_COMPRESS_FUNCTIONS)
-		return (EINVAL);
-
-	if (drrwe->drr_object > rwa->max_object)
-		rwa->max_object = drrwe->drr_object;
-
-	tx = dmu_tx_create(rwa->os);
-
-	dmu_tx_hold_write(tx, drrwe->drr_object,
-	    drrwe->drr_offset, drrwe->drr_length);
-	err = dmu_tx_assign(tx, TXG_WAIT);
-	if (err != 0) {
-		dmu_tx_abort(tx);
-		return (err);
-	}
-
-	dmu_write_embedded(rwa->os, drrwe->drr_object,
-	    drrwe->drr_offset, data, drrwe->drr_etype,
-	    drrwe->drr_compression, drrwe->drr_lsize, drrwe->drr_psize,
-	    rwa->byteswap ^ ZFS_HOST_BYTEORDER, tx);
-
-	/* See comment in restore_write. */
-	save_resume_state(rwa, drrwe->drr_object, drrwe->drr_offset, tx);
-	dmu_tx_commit(tx);
-	return (0);
-}
-
-static int
-receive_spill(struct receive_writer_arg *rwa, struct drr_spill *drrs,
-    void *data)
-{
-	dmu_tx_t *tx;
-	dmu_buf_t *db, *db_spill;
-	int err;
-
-	if (drrs->drr_length < SPA_MINBLOCKSIZE ||
-	    drrs->drr_length > spa_maxblocksize(dmu_objset_spa(rwa->os)))
-		return (SET_ERROR(EINVAL));
-
-	if (dmu_object_info(rwa->os, drrs->drr_object, NULL) != 0)
-		return (SET_ERROR(EINVAL));
-
-	if (drrs->drr_object > rwa->max_object)
-		rwa->max_object = drrs->drr_object;
-
-	VERIFY0(dmu_bonus_hold(rwa->os, drrs->drr_object, FTAG, &db));
-	if ((err = dmu_spill_hold_by_bonus(db, FTAG, &db_spill)) != 0) {
-		dmu_buf_rele(db, FTAG);
-		return (err);
-	}
-
-	tx = dmu_tx_create(rwa->os);
-
-	dmu_tx_hold_spill(tx, db->db_object);
-
-	err = dmu_tx_assign(tx, TXG_WAIT);
-	if (err != 0) {
-		dmu_buf_rele(db, FTAG);
-		dmu_buf_rele(db_spill, FTAG);
-		dmu_tx_abort(tx);
-		return (err);
-	}
-	dmu_buf_will_dirty(db_spill, tx);
-
-	if (db_spill->db_size < drrs->drr_length)
-		VERIFY(0 == dbuf_spill_set_blksz(db_spill,
-		    drrs->drr_length, tx));
-	bcopy(data, db_spill->db_data, drrs->drr_length);
-
-	dmu_buf_rele(db, FTAG);
-	dmu_buf_rele(db_spill, FTAG);
-
-	dmu_tx_commit(tx);
-	return (0);
-}
-
-/* ARGSUSED */
-static int
-receive_free(struct receive_writer_arg *rwa, struct drr_free *drrf)
-{
-	int err;
-
-	if (drrf->drr_length != -1ULL &&
-	    drrf->drr_offset + drrf->drr_length < drrf->drr_offset)
-		return (SET_ERROR(EINVAL));
-
-	if (dmu_object_info(rwa->os, drrf->drr_object, NULL) != 0)
-		return (SET_ERROR(EINVAL));
-
-	if (drrf->drr_object > rwa->max_object)
-		rwa->max_object = drrf->drr_object;
-
-	err = dmu_free_long_range(rwa->os, drrf->drr_object,
-	    drrf->drr_offset, drrf->drr_length);
-
-	return (err);
-}
-
-/* used to destroy the drc_ds on error */
-static void
-dmu_recv_cleanup_ds(dmu_recv_cookie_t *drc)
-{
-	if (drc->drc_resumable) {
-		/* wait for our resume state to be written to disk */
-		txg_wait_synced(drc->drc_ds->ds_dir->dd_pool, 0);
-		dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
-	} else {
-		char name[ZFS_MAX_DATASET_NAME_LEN];
-		dsl_dataset_name(drc->drc_ds, name);
-		dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
-		(void) dsl_destroy_head(name);
-	}
-}
-
-static void
-receive_cksum(struct receive_arg *ra, int len, void *buf)
-{
-	if (ra->byteswap) {
-		(void) fletcher_4_incremental_byteswap(buf, len, &ra->cksum);
-	} else {
-		(void) fletcher_4_incremental_native(buf, len, &ra->cksum);
-	}
-}
-
-/*
- * Read the payload into a buffer of size len, and update the current record's
- * payload field.
- * Allocate ra->next_rrd and read the next record's header into
- * ra->next_rrd->header.
- * Verify checksum of payload and next record.
- */
-static int
-receive_read_payload_and_next_header(struct receive_arg *ra, int len, void *buf)
-{
-	int err;
-
-	if (len != 0) {
-		ASSERT3U(len, <=, SPA_MAXBLOCKSIZE);
-		err = receive_read(ra, len, buf);
-		if (err != 0)
-			return (err);
-		receive_cksum(ra, len, buf);
-
-		/* note: rrd is NULL when reading the begin record's payload */
-		if (ra->rrd != NULL) {
-			ra->rrd->payload = buf;
-			ra->rrd->payload_size = len;
-			ra->rrd->bytes_read = ra->bytes_read;
-		}
-	}
-
-	ra->prev_cksum = ra->cksum;
-
-	ra->next_rrd = kmem_zalloc(sizeof (*ra->next_rrd), KM_SLEEP);
-	err = receive_read(ra, sizeof (ra->next_rrd->header),
-	    &ra->next_rrd->header);
-	ra->next_rrd->bytes_read = ra->bytes_read;
-	if (err != 0) {
-		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
-		ra->next_rrd = NULL;
-		return (err);
-	}
-	if (ra->next_rrd->header.drr_type == DRR_BEGIN) {
-		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
-		ra->next_rrd = NULL;
-		return (SET_ERROR(EINVAL));
-	}
-
-	/*
-	 * Note: checksum is of everything up to but not including the
-	 * checksum itself.
-	 */
-	ASSERT3U(offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
-	    ==, sizeof (dmu_replay_record_t) - sizeof (zio_cksum_t));
-	receive_cksum(ra,
-	    offsetof(dmu_replay_record_t, drr_u.drr_checksum.drr_checksum),
-	    &ra->next_rrd->header);
-
-	zio_cksum_t cksum_orig =
-	    ra->next_rrd->header.drr_u.drr_checksum.drr_checksum;
-	zio_cksum_t *cksump =
-	    &ra->next_rrd->header.drr_u.drr_checksum.drr_checksum;
-
-	if (ra->byteswap)
-		byteswap_record(&ra->next_rrd->header);
-
-	if ((!ZIO_CHECKSUM_IS_ZERO(cksump)) &&
-	    !ZIO_CHECKSUM_EQUAL(ra->cksum, *cksump)) {
-		kmem_free(ra->next_rrd, sizeof (*ra->next_rrd));
-		ra->next_rrd = NULL;
-		return (SET_ERROR(ECKSUM));
-	}
-
-	receive_cksum(ra, sizeof (cksum_orig), &cksum_orig);
-
-	return (0);
-}
-
-static void
-objlist_create(struct objlist *list)
-{
-	list_create(&list->list, sizeof (struct receive_objnode),
-	    offsetof(struct receive_objnode, node));
-	list->last_lookup = 0;
-}
-
-static void
-objlist_destroy(struct objlist *list)
-{
-	for (struct receive_objnode *n = list_remove_head(&list->list);
-	    n != NULL; n = list_remove_head(&list->list)) {
-		kmem_free(n, sizeof (*n));
-	}
-	list_destroy(&list->list);
-}
-
-/*
- * This function looks through the objlist to see if the specified object number
- * is contained in the objlist.  In the process, it will remove all object
- * numbers in the list that are smaller than the specified object number.  Thus,
- * any lookup of an object number smaller than a previously looked up object
- * number will always return false; therefore, all lookups should be done in
- * ascending order.
- */
-static boolean_t
-objlist_exists(struct objlist *list, uint64_t object)
-{
-	struct receive_objnode *node = list_head(&list->list);
-	ASSERT3U(object, >=, list->last_lookup);
-	list->last_lookup = object;
-	while (node != NULL && node->object < object) {
-		VERIFY3P(node, ==, list_remove_head(&list->list));
-		kmem_free(node, sizeof (*node));
-		node = list_head(&list->list);
-	}
-	return (node != NULL && node->object == object);
-}
-
-/*
- * The objlist is a list of object numbers stored in ascending order.  However,
- * the insertion of new object numbers does not seek out the correct location to
- * store a new object number; instead, it appends it to the list for simplicity.
- * Thus, any users must take care to only insert new object numbers in ascending
- * order.
- */
-static void
-objlist_insert(struct objlist *list, uint64_t object)
-{
-	struct receive_objnode *node = kmem_zalloc(sizeof (*node), KM_SLEEP);
-	node->object = object;
-#ifdef ZFS_DEBUG
-	struct receive_objnode *last_object = list_tail(&list->list);
-	uint64_t last_objnum = (last_object != NULL ? last_object->object : 0);
-	ASSERT3U(node->object, >, last_objnum);
-#endif
-	list_insert_tail(&list->list, node);
-}
-
-/*
- * Issue the prefetch reads for any necessary indirect blocks.
- *
- * We use the object ignore list to tell us whether or not to issue prefetches
- * for a given object.  We do this for both correctness (in case the blocksize
- * of an object has changed) and performance (if the object doesn't exist, don't
- * needlessly try to issue prefetches).  We also trim the list as we go through
- * the stream to prevent it from growing to an unbounded size.
- *
- * The object numbers within will always be in sorted order, and any write
- * records we see will also be in sorted order, but they're not sorted with
- * respect to each other (i.e. we can get several object records before
- * receiving each object's write records).  As a result, once we've reached a
- * given object number, we can safely remove any reference to lower object
- * numbers in the ignore list. In practice, we receive up to 32 object records
- * before receiving write records, so the list can have up to 32 nodes in it.
- */
-/* ARGSUSED */
-static void
-receive_read_prefetch(struct receive_arg *ra,
-    uint64_t object, uint64_t offset, uint64_t length)
-{
-	if (!objlist_exists(&ra->ignore_objlist, object)) {
-		dmu_prefetch(ra->os, object, 1, offset, length,
-		    ZIO_PRIORITY_SYNC_READ);
-	}
-}
-
-/*
- * Read records off the stream, issuing any necessary prefetches.
- */
-static int
-receive_read_record(struct receive_arg *ra)
-{
-	int err;
-
-	switch (ra->rrd->header.drr_type) {
-	case DRR_OBJECT:
-	{
-		struct drr_object *drro = &ra->rrd->header.drr_u.drr_object;
-		uint32_t size = P2ROUNDUP(drro->drr_bonuslen, 8);
-		void *buf = kmem_zalloc(size, KM_SLEEP);
-		dmu_object_info_t doi;
-		err = receive_read_payload_and_next_header(ra, size, buf);
-		if (err != 0) {
-			kmem_free(buf, size);
-			return (err);
-		}
-		err = dmu_object_info(ra->os, drro->drr_object, &doi);
-		/*
-		 * See receive_read_prefetch for an explanation why we're
-		 * storing this object in the ignore_obj_list.
-		 */
-		if (err == ENOENT ||
-		    (err == 0 && doi.doi_data_block_size != drro->drr_blksz)) {
-			objlist_insert(&ra->ignore_objlist, drro->drr_object);
-			err = 0;
-		}
-		return (err);
-	}
-	case DRR_FREEOBJECTS:
-	{
-		err = receive_read_payload_and_next_header(ra, 0, NULL);
-		return (err);
-	}
-	case DRR_WRITE:
-	{
-		struct drr_write *drrw = &ra->rrd->header.drr_u.drr_write;
-		arc_buf_t *abuf;
-		boolean_t is_meta = DMU_OT_IS_METADATA(drrw->drr_type);
-		if (DRR_WRITE_COMPRESSED(drrw)) {
-			ASSERT3U(drrw->drr_compressed_size, >, 0);
-			ASSERT3U(drrw->drr_logical_size, >=,
-			    drrw->drr_compressed_size);
-			ASSERT(!is_meta);
-			abuf = arc_loan_compressed_buf(
-			    dmu_objset_spa(ra->os),
-			    drrw->drr_compressed_size, drrw->drr_logical_size,
-			    drrw->drr_compressiontype);
-		} else {
-			abuf = arc_loan_buf(dmu_objset_spa(ra->os),
-			    is_meta, drrw->drr_logical_size);
-		}
-
-		err = receive_read_payload_and_next_header(ra,
-		    DRR_WRITE_PAYLOAD_SIZE(drrw), abuf->b_data);
-		if (err != 0) {
-			dmu_return_arcbuf(abuf);
-			return (err);
-		}
-		ra->rrd->write_buf = abuf;
-		receive_read_prefetch(ra, drrw->drr_object, drrw->drr_offset,
-		    drrw->drr_logical_size);
-		return (err);
-	}
-	case DRR_WRITE_BYREF:
-	{
-		struct drr_write_byref *drrwb =
-		    &ra->rrd->header.drr_u.drr_write_byref;
-		err = receive_read_payload_and_next_header(ra, 0, NULL);
-		receive_read_prefetch(ra, drrwb->drr_object, drrwb->drr_offset,
-		    drrwb->drr_length);
-		return (err);
-	}
-	case DRR_WRITE_EMBEDDED:
-	{
-		struct drr_write_embedded *drrwe =
-		    &ra->rrd->header.drr_u.drr_write_embedded;
-		uint32_t size = P2ROUNDUP(drrwe->drr_psize, 8);
-		void *buf = kmem_zalloc(size, KM_SLEEP);
-
-		err = receive_read_payload_and_next_header(ra, size, buf);
-		if (err != 0) {
-			kmem_free(buf, size);
-			return (err);
-		}
-
-		receive_read_prefetch(ra, drrwe->drr_object, drrwe->drr_offset,
-		    drrwe->drr_length);
-		return (err);
-	}
-	case DRR_FREE:
-	{
-		/*
-		 * It might be beneficial to prefetch indirect blocks here, but
-		 * we don't really have the data to decide for sure.
-		 */
-		err = receive_read_payload_and_next_header(ra, 0, NULL);
-		return (err);
-	}
-	case DRR_END:
-	{
-		struct drr_end *drre = &ra->rrd->header.drr_u.drr_end;
-		if (!ZIO_CHECKSUM_EQUAL(ra->prev_cksum, drre->drr_checksum))
-			return (SET_ERROR(ECKSUM));
-		return (0);
-	}
-	case DRR_SPILL:
-	{
-		struct drr_spill *drrs = &ra->rrd->header.drr_u.drr_spill;
-		void *buf = kmem_zalloc(drrs->drr_length, KM_SLEEP);
-		err = receive_read_payload_and_next_header(ra, drrs->drr_length,
-		    buf);
-		if (err != 0)
-			kmem_free(buf, drrs->drr_length);
-		return (err);
-	}
-	default:
-		return (SET_ERROR(EINVAL));
-	}
-}
-
-/*
- * Commit the records to the pool.
- */
-static int
-receive_process_record(struct receive_writer_arg *rwa,
-    struct receive_record_arg *rrd)
-{
-	int err;
-
-	/* Processing in order, therefore bytes_read should be increasing. */
-	ASSERT3U(rrd->bytes_read, >=, rwa->bytes_read);
-	rwa->bytes_read = rrd->bytes_read;
-
-	switch (rrd->header.drr_type) {
-	case DRR_OBJECT:
-	{
-		struct drr_object *drro = &rrd->header.drr_u.drr_object;
-		err = receive_object(rwa, drro, rrd->payload);
-		kmem_free(rrd->payload, rrd->payload_size);
-		rrd->payload = NULL;
-		return (err);
-	}
-	case DRR_FREEOBJECTS:
-	{
-		struct drr_freeobjects *drrfo =
-		    &rrd->header.drr_u.drr_freeobjects;
-		return (receive_freeobjects(rwa, drrfo));
-	}
-	case DRR_WRITE:
-	{
-		struct drr_write *drrw = &rrd->header.drr_u.drr_write;
-		err = receive_write(rwa, drrw, rrd->write_buf);
-		/* if receive_write() is successful, it consumes the arc_buf */
-		if (err != 0)
-			dmu_return_arcbuf(rrd->write_buf);
-		rrd->write_buf = NULL;
-		rrd->payload = NULL;
-		return (err);
-	}
-	case DRR_WRITE_BYREF:
-	{
-		struct drr_write_byref *drrwbr =
-		    &rrd->header.drr_u.drr_write_byref;
-		return (receive_write_byref(rwa, drrwbr));
-	}
-	case DRR_WRITE_EMBEDDED:
-	{
-		struct drr_write_embedded *drrwe =
-		    &rrd->header.drr_u.drr_write_embedded;
-		err = receive_write_embedded(rwa, drrwe, rrd->payload);
-		kmem_free(rrd->payload, rrd->payload_size);
-		rrd->payload = NULL;
-		return (err);
-	}
-	case DRR_FREE:
-	{
-		struct drr_free *drrf = &rrd->header.drr_u.drr_free;
-		return (receive_free(rwa, drrf));
-	}
-	case DRR_SPILL:
-	{
-		struct drr_spill *drrs = &rrd->header.drr_u.drr_spill;
-		err = receive_spill(rwa, drrs, rrd->payload);
-		kmem_free(rrd->payload, rrd->payload_size);
-		rrd->payload = NULL;
-		return (err);
-	}
-	default:
-		return (SET_ERROR(EINVAL));
-	}
-}
-
-/*
- * dmu_recv_stream's worker thread; pull records off the queue, and then call
- * receive_process_record  When we're done, signal the main thread and exit.
- */
-static void
-receive_writer_thread(void *arg)
-{
-	struct receive_writer_arg *rwa = arg;
-	struct receive_record_arg *rrd;
-	for (rrd = bqueue_dequeue(&rwa->q); !rrd->eos_marker;
-	    rrd = bqueue_dequeue(&rwa->q)) {
-		/*
-		 * If there's an error, the main thread will stop putting things
-		 * on the queue, but we need to clear everything in it before we
-		 * can exit.
-		 */
-		if (rwa->err == 0) {
-			rwa->err = receive_process_record(rwa, rrd);
-		} else if (rrd->write_buf != NULL) {
-			dmu_return_arcbuf(rrd->write_buf);
-			rrd->write_buf = NULL;
-			rrd->payload = NULL;
-		} else if (rrd->payload != NULL) {
-			kmem_free(rrd->payload, rrd->payload_size);
-			rrd->payload = NULL;
-		}
-		kmem_free(rrd, sizeof (*rrd));
-	}
-	kmem_free(rrd, sizeof (*rrd));
-	mutex_enter(&rwa->mutex);
-	rwa->done = B_TRUE;
-	cv_signal(&rwa->cv);
-	mutex_exit(&rwa->mutex);
-	thread_exit();
-}
-
-static int
-resume_check(struct receive_arg *ra, nvlist_t *begin_nvl)
-{
-	uint64_t val;
-	objset_t *mos = dmu_objset_pool(ra->os)->dp_meta_objset;
-	uint64_t dsobj = dmu_objset_id(ra->os);
-	uint64_t resume_obj, resume_off;
-
-	if (nvlist_lookup_uint64(begin_nvl,
-	    "resume_object", &resume_obj) != 0 ||
-	    nvlist_lookup_uint64(begin_nvl,
-	    "resume_offset", &resume_off) != 0) {
-		return (SET_ERROR(EINVAL));
-	}
-	VERIFY0(zap_lookup(mos, dsobj,
-	    DS_FIELD_RESUME_OBJECT, sizeof (val), 1, &val));
-	if (resume_obj != val)
-		return (SET_ERROR(EINVAL));
-	VERIFY0(zap_lookup(mos, dsobj,
-	    DS_FIELD_RESUME_OFFSET, sizeof (val), 1, &val));
-	if (resume_off != val)
-		return (SET_ERROR(EINVAL));
-
-	return (0);
-}
-
-/*
- * Read in the stream's records, one by one, and apply them to the pool.  There
- * are two threads involved; the thread that calls this function will spin up a
- * worker thread, read the records off the stream one by one, and issue
- * prefetches for any necessary indirect blocks.  It will then push the records
- * onto an internal blocking queue.  The worker thread will pull the records off
- * the queue, and actually write the data into the DMU.  This way, the worker
- * thread doesn't have to wait for reads to complete, since everything it needs
- * (the indirect blocks) will be prefetched.
- *
- * NB: callers *must* call dmu_recv_end() if this succeeds.
- */
-int
-dmu_recv_stream(dmu_recv_cookie_t *drc, vnode_t *vp, offset_t *voffp,
-    int cleanup_fd, uint64_t *action_handlep)
-{
-	int err = 0;
-	struct receive_arg ra = { 0 };
-	struct receive_writer_arg rwa = { 0 };
-	int featureflags;
-	nvlist_t *begin_nvl = NULL;
-
-	ra.byteswap = drc->drc_byteswap;
-	ra.cksum = drc->drc_cksum;
-	ra.vp = vp;
-	ra.voff = *voffp;
-
-	if (dsl_dataset_is_zapified(drc->drc_ds)) {
-		(void) zap_lookup(drc->drc_ds->ds_dir->dd_pool->dp_meta_objset,
-		    drc->drc_ds->ds_object, DS_FIELD_RESUME_BYTES,
-		    sizeof (ra.bytes_read), 1, &ra.bytes_read);
-	}
-
-	objlist_create(&ra.ignore_objlist);
-
-	/* these were verified in dmu_recv_begin */
-	ASSERT3U(DMU_GET_STREAM_HDRTYPE(drc->drc_drrb->drr_versioninfo), ==,
-	    DMU_SUBSTREAM);
-	ASSERT3U(drc->drc_drrb->drr_type, <, DMU_OST_NUMTYPES);
-
-	/*
-	 * Open the objset we are modifying.
-	 */
-	VERIFY0(dmu_objset_from_ds(drc->drc_ds, &ra.os));
-
-	ASSERT(dsl_dataset_phys(drc->drc_ds)->ds_flags & DS_FLAG_INCONSISTENT);
-
-	featureflags = DMU_GET_FEATUREFLAGS(drc->drc_drrb->drr_versioninfo);
-
-	/* if this stream is dedup'ed, set up the avl tree for guid mapping */
-	if (featureflags & DMU_BACKUP_FEATURE_DEDUP) {
-		minor_t minor;
-
-		if (cleanup_fd == -1) {
-			ra.err = SET_ERROR(EBADF);
-			goto out;
-		}
-		ra.err = zfs_onexit_fd_hold(cleanup_fd, &minor);
-		if (ra.err != 0) {
-			cleanup_fd = -1;
-			goto out;
-		}
-
-		if (*action_handlep == 0) {
-			rwa.guid_to_ds_map =
-			    kmem_alloc(sizeof (avl_tree_t), KM_SLEEP);
-			avl_create(rwa.guid_to_ds_map, guid_compare,
-			    sizeof (guid_map_entry_t),
-			    offsetof(guid_map_entry_t, avlnode));
-			err = zfs_onexit_add_cb(minor,
-			    free_guid_map_onexit, rwa.guid_to_ds_map,
-			    action_handlep);
-			if (ra.err != 0)
-				goto out;
-		} else {
-			err = zfs_onexit_cb_data(minor, *action_handlep,
-			    (void **)&rwa.guid_to_ds_map);
-			if (ra.err != 0)
-				goto out;
-		}
-
-		drc->drc_guid_to_ds_map = rwa.guid_to_ds_map;
-	}
-
-	uint32_t payloadlen = drc->drc_drr_begin->drr_payloadlen;
-	void *payload = NULL;
-	if (payloadlen != 0)
-		payload = kmem_alloc(payloadlen, KM_SLEEP);
-
-	err = receive_read_payload_and_next_header(&ra, payloadlen, payload);
-	if (err != 0) {
-		if (payloadlen != 0)
-			kmem_free(payload, payloadlen);
-		goto out;
-	}
-	if (payloadlen != 0) {
-		err = nvlist_unpack(payload, payloadlen, &begin_nvl, KM_SLEEP);
-		kmem_free(payload, payloadlen);
-		if (err != 0)
-			goto out;
-	}
-
-	if (featureflags & DMU_BACKUP_FEATURE_RESUMING) {
-		err = resume_check(&ra, begin_nvl);
-		if (err != 0)
-			goto out;
-	}
-
-	(void) bqueue_init(&rwa.q, zfs_recv_queue_length,
-	    offsetof(struct receive_record_arg, node));
-	cv_init(&rwa.cv, NULL, CV_DEFAULT, NULL);
-	mutex_init(&rwa.mutex, NULL, MUTEX_DEFAULT, NULL);
-	rwa.os = ra.os;
-	rwa.byteswap = drc->drc_byteswap;
-	rwa.resumable = drc->drc_resumable;
-
-	(void) thread_create(NULL, 0, receive_writer_thread, &rwa, 0, curproc,
-	    TS_RUN, minclsyspri);
-	/*
-	 * We're reading rwa.err without locks, which is safe since we are the
-	 * only reader, and the worker thread is the only writer.  It's ok if we
-	 * miss a write for an iteration or two of the loop, since the writer
-	 * thread will keep freeing records we send it until we send it an eos
-	 * marker.
-	 *
-	 * We can leave this loop in 3 ways:  First, if rwa.err is
-	 * non-zero.  In that case, the writer thread will free the rrd we just
-	 * pushed.  Second, if  we're interrupted; in that case, either it's the
-	 * first loop and ra.rrd was never allocated, or it's later, and ra.rrd
-	 * has been handed off to the writer thread who will free it.  Finally,
-	 * if receive_read_record fails or we're at the end of the stream, then
-	 * we free ra.rrd and exit.
-	 */
-	while (rwa.err == 0) {
-		if (issig(JUSTLOOKING) && issig(FORREAL)) {
-			err = SET_ERROR(EINTR);
-			break;
-		}
-
-		ASSERT3P(ra.rrd, ==, NULL);
-		ra.rrd = ra.next_rrd;
-		ra.next_rrd = NULL;
-		/* Allocates and loads header into ra.next_rrd */
-		err = receive_read_record(&ra);
-
-		if (ra.rrd->header.drr_type == DRR_END || err != 0) {
-			kmem_free(ra.rrd, sizeof (*ra.rrd));
-			ra.rrd = NULL;
-			break;
-		}
-
-		bqueue_enqueue(&rwa.q, ra.rrd,
-		    sizeof (struct receive_record_arg) + ra.rrd->payload_size);
-		ra.rrd = NULL;
-	}
-	if (ra.next_rrd == NULL)
-		ra.next_rrd = kmem_zalloc(sizeof (*ra.next_rrd), KM_SLEEP);
-	ra.next_rrd->eos_marker = B_TRUE;
-	bqueue_enqueue(&rwa.q, ra.next_rrd, 1);
-
-	mutex_enter(&rwa.mutex);
-	while (!rwa.done) {
-		cv_wait(&rwa.cv, &rwa.mutex);
-	}
-	mutex_exit(&rwa.mutex);
-
-	/*
-	 * If we are receiving a full stream as a clone, all object IDs which
-	 * are greater than the maximum ID referenced in the stream are
-	 * by definition unused and must be freed. Note that it's possible that
-	 * we've resumed this send and the first record we received was the END
-	 * record. In that case, max_object would be 0, but we shouldn't start
-	 * freeing all objects from there; instead we should start from the
-	 * resumeobj.
-	 */
-	if (drc->drc_clone && drc->drc_drrb->drr_fromguid == 0) {
-		uint64_t obj;
-		if (nvlist_lookup_uint64(begin_nvl, "resume_object", &obj) != 0)
-			obj = 0;
-		if (rwa.max_object > obj)
-			obj = rwa.max_object;
-		obj++;
-		int free_err = 0;
-		int next_err = 0;
-
-		while (next_err == 0) {
-			free_err = dmu_free_long_object(rwa.os, obj);
-			if (free_err != 0 && free_err != ENOENT)
-				break;
-
-			next_err = dmu_object_next(rwa.os, &obj, FALSE, 0);
-		}
-
-		if (err == 0) {
-			if (free_err != 0 && free_err != ENOENT)
-				err = free_err;
-			else if (next_err != ESRCH)
-				err = next_err;
-		}
-	}
-
-	cv_destroy(&rwa.cv);
-	mutex_destroy(&rwa.mutex);
-	bqueue_destroy(&rwa.q);
-	if (err == 0)
-		err = rwa.err;
-
-out:
-	nvlist_free(begin_nvl);
-	if ((featureflags & DMU_BACKUP_FEATURE_DEDUP) && (cleanup_fd != -1))
-		zfs_onexit_fd_rele(cleanup_fd);
-
-	if (err != 0) {
-		/*
-		 * Clean up references. If receive is not resumable,
-		 * destroy what we created, so we don't leave it in
-		 * the inconsistent state.
-		 */
-		dmu_recv_cleanup_ds(drc);
-	}
-
-	*voffp = ra.voff;
-	objlist_destroy(&ra.ignore_objlist);
-	return (err);
-}
-
-static int
-dmu_recv_end_check(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_cookie_t *drc = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-	int error;
-
-	ASSERT3P(drc->drc_ds->ds_owner, ==, dmu_recv_tag);
-
-	if (!drc->drc_newfs) {
-		dsl_dataset_t *origin_head;
-
-		error = dsl_dataset_hold(dp, drc->drc_tofs, FTAG, &origin_head);
-		if (error != 0)
-			return (error);
-		if (drc->drc_force) {
-			/*
-			 * We will destroy any snapshots in tofs (i.e. before
-			 * origin_head) that are after the origin (which is
-			 * the snap before drc_ds, because drc_ds can not
-			 * have any snaps of its own).
-			 */
-			uint64_t obj;
-
-			obj = dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
-			while (obj !=
-			    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj) {
-				dsl_dataset_t *snap;
-				error = dsl_dataset_hold_obj(dp, obj, FTAG,
-				    &snap);
-				if (error != 0)
-					break;
-				if (snap->ds_dir != origin_head->ds_dir)
-					error = SET_ERROR(EINVAL);
-				if (error == 0)  {
-					error = dsl_destroy_snapshot_check_impl(
-					    snap, B_FALSE);
-				}
-				obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
-				dsl_dataset_rele(snap, FTAG);
-				if (error != 0)
-					break;
-			}
-			if (error != 0) {
-				dsl_dataset_rele(origin_head, FTAG);
-				return (error);
-			}
-		}
-		error = dsl_dataset_clone_swap_check_impl(drc->drc_ds,
-		    origin_head, drc->drc_force, drc->drc_owner, tx);
-		if (error != 0) {
-			dsl_dataset_rele(origin_head, FTAG);
-			return (error);
-		}
-		error = dsl_dataset_snapshot_check_impl(origin_head,
-		    drc->drc_tosnap, tx, B_TRUE, 1, drc->drc_cred);
-		dsl_dataset_rele(origin_head, FTAG);
-		if (error != 0)
-			return (error);
-
-		error = dsl_destroy_head_check_impl(drc->drc_ds, 1);
-	} else {
-		error = dsl_dataset_snapshot_check_impl(drc->drc_ds,
-		    drc->drc_tosnap, tx, B_TRUE, 1, drc->drc_cred);
-	}
-	return (error);
-}
-
-static void
-dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
-{
-	dmu_recv_cookie_t *drc = arg;
-	dsl_pool_t *dp = dmu_tx_pool(tx);
-
-	spa_history_log_internal_ds(drc->drc_ds, "finish receiving",
-	    tx, "snap=%s", drc->drc_tosnap);
-
-	if (!drc->drc_newfs) {
-		dsl_dataset_t *origin_head;
-
-		VERIFY0(dsl_dataset_hold(dp, drc->drc_tofs, FTAG,
-		    &origin_head));
-
-		if (drc->drc_force) {
-			/*
-			 * Destroy any snapshots of drc_tofs (origin_head)
-			 * after the origin (the snap before drc_ds).
-			 */
-			uint64_t obj;
-
-			obj = dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
-			while (obj !=
-			    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj) {
-				dsl_dataset_t *snap;
-				VERIFY0(dsl_dataset_hold_obj(dp, obj, FTAG,
-				    &snap));
-				ASSERT3P(snap->ds_dir, ==, origin_head->ds_dir);
-				obj = dsl_dataset_phys(snap)->ds_prev_snap_obj;
-				dsl_destroy_snapshot_sync_impl(snap,
-				    B_FALSE, tx);
-				dsl_dataset_rele(snap, FTAG);
-			}
-		}
-		VERIFY3P(drc->drc_ds->ds_prev, ==,
-		    origin_head->ds_prev);
-
-		dsl_dataset_clone_swap_sync_impl(drc->drc_ds,
-		    origin_head, tx);
-		dsl_dataset_snapshot_sync_impl(origin_head,
-		    drc->drc_tosnap, tx);
-
-		/* set snapshot's creation time and guid */
-		dmu_buf_will_dirty(origin_head->ds_prev->ds_dbuf, tx);
-		dsl_dataset_phys(origin_head->ds_prev)->ds_creation_time =
-		    drc->drc_drrb->drr_creation_time;
-		dsl_dataset_phys(origin_head->ds_prev)->ds_guid =
-		    drc->drc_drrb->drr_toguid;
-		dsl_dataset_phys(origin_head->ds_prev)->ds_flags &=
-		    ~DS_FLAG_INCONSISTENT;
-
-		dmu_buf_will_dirty(origin_head->ds_dbuf, tx);
-		dsl_dataset_phys(origin_head)->ds_flags &=
-		    ~DS_FLAG_INCONSISTENT;
-
-		drc->drc_newsnapobj =
-		    dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
-
-		dsl_dataset_rele(origin_head, FTAG);
-		dsl_destroy_head_sync_impl(drc->drc_ds, tx);
-
-		if (drc->drc_owner != NULL)
-			VERIFY3P(origin_head->ds_owner, ==, drc->drc_owner);
-	} else {
-		dsl_dataset_t *ds = drc->drc_ds;
-
-		dsl_dataset_snapshot_sync_impl(ds, drc->drc_tosnap, tx);
-
-		/* set snapshot's creation time and guid */
-		dmu_buf_will_dirty(ds->ds_prev->ds_dbuf, tx);
-		dsl_dataset_phys(ds->ds_prev)->ds_creation_time =
-		    drc->drc_drrb->drr_creation_time;
-		dsl_dataset_phys(ds->ds_prev)->ds_guid =
-		    drc->drc_drrb->drr_toguid;
-		dsl_dataset_phys(ds->ds_prev)->ds_flags &=
-		    ~DS_FLAG_INCONSISTENT;
-
-		dmu_buf_will_dirty(ds->ds_dbuf, tx);
-		dsl_dataset_phys(ds)->ds_flags &= ~DS_FLAG_INCONSISTENT;
-		if (dsl_dataset_has_resume_receive_state(ds)) {
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_FROMGUID, tx);
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_OBJECT, tx);
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_OFFSET, tx);
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_BYTES, tx);
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_TOGUID, tx);
-			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
-			    DS_FIELD_RESUME_TONAME, tx);
-		}
-		drc->drc_newsnapobj =
-		    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj;
-	}
-	/*
-	 * Release the hold from dmu_recv_begin.  This must be done before
-	 * we return to open context, so that when we free the dataset's dnode,
-	 * we can evict its bonus buffer.
-	 */
-	dsl_dataset_disown(drc->drc_ds, dmu_recv_tag);
-	drc->drc_ds = NULL;
-}
-
-static int
-add_ds_to_guidmap(const char *name, avl_tree_t *guid_map, uint64_t snapobj)
-{
-	dsl_pool_t *dp;
-	dsl_dataset_t *snapds;
-	guid_map_entry_t *gmep;
-	int err;
-
-	ASSERT(guid_map != NULL);
-
-	err = dsl_pool_hold(name, FTAG, &dp);
-	if (err != 0)
-		return (err);
-	gmep = kmem_alloc(sizeof (*gmep), KM_SLEEP);
-	err = dsl_dataset_hold_obj(dp, snapobj, gmep, &snapds);
-	if (err == 0) {
-		gmep->guid = dsl_dataset_phys(snapds)->ds_guid;
-		gmep->gme_ds = snapds;
-		avl_add(guid_map, gmep);
-		dsl_dataset_long_hold(snapds, gmep);
-	} else {
-		kmem_free(gmep, sizeof (*gmep));
-	}
-
-	dsl_pool_rele(dp, FTAG);
-	return (err);
-}
-
-static int dmu_recv_end_modified_blocks = 3;
-
-static int
-dmu_recv_existing_end(dmu_recv_cookie_t *drc)
-{
-#ifdef _KERNEL
-	/*
-	 * We will be destroying the ds; make sure its origin is unmounted if
-	 * necessary.
-	 */
-	char name[ZFS_MAX_DATASET_NAME_LEN];
-	dsl_dataset_name(drc->drc_ds, name);
-	zfs_destroy_unmount_origin(name);
-#endif
-
-	return (dsl_sync_task(drc->drc_tofs,
-	    dmu_recv_end_check, dmu_recv_end_sync, drc,
-	    dmu_recv_end_modified_blocks, ZFS_SPACE_CHECK_NORMAL));
-}
-
-static int
-dmu_recv_new_end(dmu_recv_cookie_t *drc)
-{
-	return (dsl_sync_task(drc->drc_tofs,
-	    dmu_recv_end_check, dmu_recv_end_sync, drc,
-	    dmu_recv_end_modified_blocks, ZFS_SPACE_CHECK_NORMAL));
-}
-
-int
-dmu_recv_end(dmu_recv_cookie_t *drc, void *owner)
-{
-	int error;
-
-	drc->drc_owner = owner;
-
-	if (drc->drc_newfs)
-		error = dmu_recv_new_end(drc);
-	else
-		error = dmu_recv_existing_end(drc);
-
-	if (error != 0) {
-		dmu_recv_cleanup_ds(drc);
-	} else if (drc->drc_guid_to_ds_map != NULL) {
-		(void) add_ds_to_guidmap(drc->drc_tofs,
-		    drc->drc_guid_to_ds_map,
-		    drc->drc_newsnapobj);
-	}
-	return (error);
-}
-
-/*
- * Return TRUE if this objset is currently being received into.
- */
-boolean_t
-dmu_objset_is_receiving(objset_t *os)
-{
-	return (os->os_dsl_dataset != NULL &&
-	    os->os_dsl_dataset->ds_owner == dmu_recv_tag);
-}
diff --git a/usr/src/uts/common/fs/zfs/dsl_dataset.c b/usr/src/uts/common/fs/zfs/dsl_dataset.c
index 27873c0d45..caa6855034 100644
--- a/usr/src/uts/common/fs/zfs/dsl_dataset.c
+++ b/usr/src/uts/common/fs/zfs/dsl_dataset.c
@@ -56,7 +56,7 @@
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_userhold.h>
 #include <sys/dsl_bookmark.h>
-#include <sys/dmu_send.h>
+#include <sys/dmu_recv.h>
 #include <sys/zio_checksum.h>
 #include <sys/zio_compress.h>
 #include <zfs_fletcher.h>
diff --git a/usr/src/uts/common/fs/zfs/sys/dmu_recv.h b/usr/src/uts/common/fs/zfs/sys/dmu_recv.h
new file mode 100644
index 0000000000..56b69e61b1
--- /dev/null
+++ b/usr/src/uts/common/fs/zfs/sys/dmu_recv.h
@@ -0,0 +1,64 @@
+/*
+ * 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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2013, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2014 Integros [integros.com]
+ */
+
+#ifndef _DMU_RECV_H
+#define	_DMU_RECV_H
+
+#include <sys/inttypes.h>
+#include <sys/spa.h>
+
+extern const char *recv_clone_name;
+
+typedef struct dmu_recv_cookie {
+	struct dsl_dataset *drc_ds;
+	struct dmu_replay_record *drc_drr_begin;
+	struct drr_begin *drc_drrb;
+	const char *drc_tofs;
+	const char *drc_tosnap;
+	boolean_t drc_newfs;
+	boolean_t drc_byteswap;
+	boolean_t drc_force;
+	boolean_t drc_resumable;
+	boolean_t drc_clone;
+	struct avl_tree *drc_guid_to_ds_map;
+	zio_cksum_t drc_cksum;
+	uint64_t drc_newsnapobj;
+	void *drc_owner;
+	cred_t *drc_cred;
+} dmu_recv_cookie_t;
+
+int dmu_recv_begin(char *tofs, char *tosnap,
+    struct dmu_replay_record *drr_begin,
+    boolean_t force, boolean_t resumable, char *origin, dmu_recv_cookie_t *drc);
+int dmu_recv_stream(dmu_recv_cookie_t *drc, struct vnode *vp, offset_t *voffp,
+    int cleanup_fd, uint64_t *action_handlep);
+int dmu_recv_end(dmu_recv_cookie_t *drc, void *owner);
+boolean_t dmu_objset_is_receiving(objset_t *os);
+
+#endif /* _DMU_RECV_H */
diff --git a/usr/src/uts/common/fs/zfs/sys/dmu_send.h b/usr/src/uts/common/fs/zfs/sys/dmu_send.h
index b8403313e9..65d8e99db6 100644
--- a/usr/src/uts/common/fs/zfs/sys/dmu_send.h
+++ b/usr/src/uts/common/fs/zfs/sys/dmu_send.h
@@ -39,8 +39,6 @@ struct drr_begin;
 struct avl_tree;
 struct dmu_replay_record;
 
-extern const char *recv_clone_name;
-
 int dmu_send(const char *tosnap, const char *fromsnap, boolean_t embedok,
     boolean_t large_block_ok, boolean_t compressok, int outfd,
     uint64_t resumeobj, uint64_t resumeoff,
@@ -53,30 +51,4 @@ int dmu_send_obj(const char *pool, uint64_t tosnap, uint64_t fromsnap,
     boolean_t embedok, boolean_t large_block_ok, boolean_t compressok,
     int outfd, struct vnode *vp, offset_t *off);
 
-typedef struct dmu_recv_cookie {
-	struct dsl_dataset *drc_ds;
-	struct dmu_replay_record *drc_drr_begin;
-	struct drr_begin *drc_drrb;
-	const char *drc_tofs;
-	const char *drc_tosnap;
-	boolean_t drc_newfs;
-	boolean_t drc_byteswap;
-	boolean_t drc_force;
-	boolean_t drc_resumable;
-	boolean_t drc_clone;
-	struct avl_tree *drc_guid_to_ds_map;
-	zio_cksum_t drc_cksum;
-	uint64_t drc_newsnapobj;
-	void *drc_owner;
-	cred_t *drc_cred;
-} dmu_recv_cookie_t;
-
-int dmu_recv_begin(char *tofs, char *tosnap,
-    struct dmu_replay_record *drr_begin,
-    boolean_t force, boolean_t resumable, char *origin, dmu_recv_cookie_t *drc);
-int dmu_recv_stream(dmu_recv_cookie_t *drc, struct vnode *vp, offset_t *voffp,
-    int cleanup_fd, uint64_t *action_handlep);
-int dmu_recv_end(dmu_recv_cookie_t *drc, void *owner);
-boolean_t dmu_objset_is_receiving(objset_t *os);
-
 #endif /* _DMU_SEND_H */
diff --git a/usr/src/uts/common/fs/zfs/sys/dsl_bookmark.h b/usr/src/uts/common/fs/zfs/sys/dsl_bookmark.h
index 3591986d7b..e477bb231c 100644
--- a/usr/src/uts/common/fs/zfs/sys/dsl_bookmark.h
+++ b/usr/src/uts/common/fs/zfs/sys/dsl_bookmark.h
@@ -20,6 +20,7 @@
 #define	_SYS_DSL_BOOKMARK_H
 
 #include <sys/zfs_context.h>
+#include <sys/dsl_dataset.h>
 
 #ifdef	__cplusplus
 extern "C" {
diff --git a/usr/src/uts/common/fs/zfs/zfs_ioctl.c b/usr/src/uts/common/fs/zfs/zfs_ioctl.c
index 6ae9c7ecb0..0af35f6327 100644
--- a/usr/src/uts/common/fs/zfs/zfs_ioctl.c
+++ b/usr/src/uts/common/fs/zfs/zfs_ioctl.c
@@ -181,6 +181,7 @@
 #include <sys/dsl_scan.h>
 #include <sharefs/share.h>
 #include <sys/dmu_objset.h>
+#include <sys/dmu_recv.h>
 #include <sys/dmu_send.h>
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_bookmark.h>