diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index ae71cdc881fe..15e350313af7 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2019 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright 2012 Milan Jurik. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  * Copyright (c) 2013 Steven Hartland.  All rights reserved.
@@ -4266,7 +4266,10 @@ zfs_do_send(int argc, char **argv)
 			flags.progress = B_TRUE;
 			break;
 		case 'D':
-			flags.dedup = B_TRUE;
+			(void) fprintf(stderr,
+			    gettext("WARNING: deduplicated send is no "
+			    "longer supported.  A regular,\n"
+			    "non-deduplicated stream will be generated.\n\n"));
 			break;
 		case 'n':
 			flags.dryrun = B_TRUE;
@@ -4333,16 +4336,6 @@ zfs_do_send(int argc, char **argv)
 		}
 	}
 
-	if (flags.dedup) {
-		(void) fprintf(stderr,
-		    gettext("WARNING: deduplicated send is "
-		    "deprecated, and will be removed in a\n"
-		    "future release. (In the future, the flag will be "
-		    "accepted, but a\n"
-		    "regular, non-deduplicated stream will be "
-		    "generated.)\n\n"));
-	}
-
 	if (flags.parsable && flags.verbosity == 0)
 		flags.verbosity = 1;
 
@@ -4351,7 +4344,7 @@ zfs_do_send(int argc, char **argv)
 
 	if (resume_token != NULL) {
 		if (fromname != NULL || flags.replicate || flags.props ||
-		    flags.backup || flags.dedup || flags.holds ||
+		    flags.backup || flags.holds ||
 		    flags.saved || redactbook != NULL) {
 			(void) fprintf(stderr,
 			    gettext("invalid flags combined with -t\n"));
@@ -4375,7 +4368,7 @@ zfs_do_send(int argc, char **argv)
 
 	if (flags.saved) {
 		if (fromname != NULL || flags.replicate || flags.props ||
-		    flags.doall || flags.backup || flags.dedup ||
+		    flags.doall || flags.backup ||
 		    flags.holds || flags.largeblock || flags.embed_data ||
 		    flags.compress || flags.raw || redactbook != NULL) {
 			(void) fprintf(stderr, gettext("incompatible flags "
diff --git a/include/libzfs.h b/include/libzfs.h
index 7633579d4344..c4f08882ed69 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright Joyent, Inc.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2016, Intel Corporation.
@@ -651,8 +651,8 @@ typedef struct sendflags {
 	/* if dataset is a clone, do incremental from its origin */
 	boolean_t fromorigin;
 
-	/* do deduplication */
-	boolean_t dedup;
+	/* field no longer used, maintained for backwards compatibility */
+	boolean_t pad;
 
 	/* send properties (ie, -p) */
 	boolean_t props;
diff --git a/include/libzfs_impl.h b/include/libzfs_impl.h
index 45c344c83666..5cec629132ae 100644
--- a/include/libzfs_impl.h
+++ b/include/libzfs_impl.h
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2018 Datto Inc.
  */
 
@@ -71,7 +71,6 @@ struct libzfs_handle {
 	int libzfs_pool_iter;
 	char libzfs_chassis_id[256];
 	boolean_t libzfs_prop_debug;
-	boolean_t libzfs_dedup_warning_printed;
 };
 
 #define	ZFSSHARE_MISS	0x01	/* Didn't find entry in cache */
diff --git a/include/sys/dmu.h b/include/sys/dmu.h
index 928ee763d482..139f3cbdfea6 100644
--- a/include/sys/dmu.h
+++ b/include/sys/dmu.h
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  * Copyright 2014 HybridCluster. All rights reserved.
@@ -864,8 +864,6 @@ int dmu_assign_arcbuf_by_dnode(dnode_t *dn, uint64_t offset,
 int dmu_assign_arcbuf_by_dbuf(dmu_buf_t *handle, uint64_t offset,
     struct arc_buf *buf, dmu_tx_t *tx);
 #define	dmu_assign_arcbuf	dmu_assign_arcbuf_by_dbuf
-void dmu_copy_from_buf(objset_t *os, uint64_t object, uint64_t offset,
-    dmu_buf_t *handle, dmu_tx_t *tx);
 #ifdef HAVE_UIO_ZEROCOPY
 int dmu_xuio_init(struct xuio *uio, int niov);
 void dmu_xuio_fini(struct xuio *uio);
diff --git a/include/sys/dmu_recv.h b/include/sys/dmu_recv.h
index e3b54e3d1981..c0a562115a20 100644
--- a/include/sys/dmu_recv.h
+++ b/include/sys/dmu_recv.h
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  */
@@ -53,10 +53,8 @@ typedef struct dmu_recv_cookie {
 	boolean_t drc_raw;
 	boolean_t drc_clone;
 	boolean_t drc_spill;
-	struct avl_tree *drc_guid_to_ds_map;
 	nvlist_t *drc_keynvl;
 	uint64_t drc_fromsnapobj;
-	uint64_t drc_newsnapobj;
 	uint64_t drc_ivset_guid;
 	void *drc_owner;
 	cred_t *drc_cred;
@@ -80,13 +78,11 @@ typedef struct dmu_recv_cookie {
 	objlist_t *drc_ignore_objlist;
 } dmu_recv_cookie_t;
 
-int dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
-    boolean_t force, boolean_t resumable, nvlist_t *localprops,
-    nvlist_t *hidden_args, char *origin, dmu_recv_cookie_t *drc,
-    zfs_file_t *fp, offset_t *voffp);
-int dmu_recv_stream(dmu_recv_cookie_t *drc, int cleanup_fd,
-    uint64_t *action_handlep, offset_t *voffp);
-int dmu_recv_end(dmu_recv_cookie_t *drc, void *owner);
-boolean_t dmu_objset_is_receiving(objset_t *os);
+int dmu_recv_begin(char *, char *, dmu_replay_record_t *,
+    boolean_t, boolean_t, nvlist_t *, nvlist_t *, char *,
+    dmu_recv_cookie_t *, zfs_file_t *, offset_t *);
+int dmu_recv_stream(dmu_recv_cookie_t *, offset_t *);
+int dmu_recv_end(dmu_recv_cookie_t *, void *);
+boolean_t dmu_objset_is_receiving(objset_t *);
 
 #endif /* _DMU_RECV_H */
diff --git a/include/sys/zfs_ioctl.h b/include/sys/zfs_ioctl.h
index da5a3ee60df3..d4ffe70bbe36 100644
--- a/include/sys/zfs_ioctl.h
+++ b/include/sys/zfs_ioctl.h
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
  * Copyright 2016 RackTop Systems.
  * Copyright (c) 2017, Intel Corporation.
  */
@@ -111,8 +111,7 @@ typedef enum drr_headertype {
 /*
  * Mask of all supported backup features
  */
-#define	DMU_BACKUP_FEATURE_MASK	(DMU_BACKUP_FEATURE_DEDUP | \
-    DMU_BACKUP_FEATURE_DEDUPPROPS | DMU_BACKUP_FEATURE_SA_SPILL | \
+#define	DMU_BACKUP_FEATURE_MASK	(DMU_BACKUP_FEATURE_SA_SPILL | \
     DMU_BACKUP_FEATURE_EMBED_DATA | DMU_BACKUP_FEATURE_LZ4 | \
     DMU_BACKUP_FEATURE_RESUMING | DMU_BACKUP_FEATURE_LARGE_BLOCKS | \
     DMU_BACKUP_FEATURE_COMPRESSED | DMU_BACKUP_FEATURE_LARGE_DNODE | \
diff --git a/include/sys/zfs_onexit.h b/include/sys/zfs_onexit.h
index 4982bd4d0afc..0fab23ff849b 100644
--- a/include/sys/zfs_onexit.h
+++ b/include/sys/zfs_onexit.h
@@ -21,6 +21,7 @@
 
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020 by Delphix. All rights reserved.
  */
 
 #ifndef	_SYS_ZFS_ONEXIT_H
@@ -54,10 +55,6 @@ extern int zfs_onexit_fd_hold(int fd, minor_t *minorp);
 extern void zfs_onexit_fd_rele(int fd);
 extern int zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
     uint64_t *action_handle);
-extern int zfs_onexit_del_cb(minor_t minor, uint64_t action_handle,
-    boolean_t fire);
-extern int zfs_onexit_cb_data(minor_t minor, uint64_t action_handle,
-    void **data);
 
 #ifdef	__cplusplus
 }
diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index 43a39e789c52..c65673dd35ba 100644
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  * Copyright (c) 2012 Pawel Jakub Dawidek <pawel@dawidek.net>.
  * All rights reserved
@@ -73,22 +73,14 @@
 extern void zfs_setprop_error(libzfs_handle_t *, zfs_prop_t, int, char *);
 
 static int zfs_receive_impl(libzfs_handle_t *, const char *, const char *,
-    recvflags_t *, int, const char *, nvlist_t *, avl_tree_t *, char **, int,
-    uint64_t *, const char *, nvlist_t *);
+    recvflags_t *, int, const char *, nvlist_t *, avl_tree_t *, char **,
+    const char *, nvlist_t *);
 static int guid_to_name_redact_snaps(libzfs_handle_t *hdl, const char *parent,
     uint64_t guid, boolean_t bookmark_ok, uint64_t *redact_snap_guids,
     uint64_t num_redact_snaps, char *name);
 static int guid_to_name(libzfs_handle_t *, const char *,
     uint64_t, boolean_t, char *);
 
-static const zio_cksum_t zero_cksum = { { 0 } };
-
-typedef struct dedup_arg {
-	int	inputfd;
-	int	outputfd;
-	libzfs_handle_t  *dedup_hdl;
-} dedup_arg_t;
-
 typedef struct progress_arg {
 	zfs_handle_t *pa_zhp;
 	int pa_fd;
@@ -97,112 +89,6 @@ typedef struct progress_arg {
 	int pa_verbosity;
 } progress_arg_t;
 
-typedef struct dataref {
-	uint64_t ref_guid;
-	uint64_t ref_object;
-	uint64_t ref_offset;
-} dataref_t;
-
-typedef struct dedup_entry {
-	struct dedup_entry	*dde_next;
-	zio_cksum_t dde_chksum;
-	uint64_t dde_prop;
-	dataref_t dde_ref;
-} dedup_entry_t;
-
-#define	MAX_DDT_PHYSMEM_PERCENT		20
-#define	SMALLEST_POSSIBLE_MAX_DDT_MB		128
-
-typedef struct dedup_table {
-	dedup_entry_t	**dedup_hash_array;
-	umem_cache_t	*ddecache;
-	uint64_t	max_ddt_size;  /* max dedup table size in bytes */
-	uint64_t	cur_ddt_size;  /* current dedup table size in bytes */
-	uint64_t	ddt_count;
-	int		numhashbits;
-	boolean_t	ddt_full;
-} dedup_table_t;
-
-static int
-high_order_bit(uint64_t n)
-{
-	int count;
-
-	for (count = 0; n != 0; count++)
-		n >>= 1;
-	return (count);
-}
-
-static size_t
-ssread(void *buf, size_t len, FILE *stream)
-{
-	size_t outlen;
-
-	if ((outlen = fread(buf, len, 1, stream)) == 0)
-		return (0);
-
-	return (outlen);
-}
-
-static void
-ddt_hash_append(libzfs_handle_t *hdl, dedup_table_t *ddt, dedup_entry_t **ddepp,
-    zio_cksum_t *cs, uint64_t prop, dataref_t *dr)
-{
-	dedup_entry_t	*dde;
-
-	if (ddt->cur_ddt_size >= ddt->max_ddt_size) {
-		if (ddt->ddt_full == B_FALSE) {
-			zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
-			    "Dedup table full.  Deduplication will continue "
-			    "with existing table entries"));
-			ddt->ddt_full = B_TRUE;
-		}
-		return;
-	}
-
-	if ((dde = umem_cache_alloc(ddt->ddecache, UMEM_DEFAULT))
-	    != NULL) {
-		assert(*ddepp == NULL);
-		dde->dde_next = NULL;
-		dde->dde_chksum = *cs;
-		dde->dde_prop = prop;
-		dde->dde_ref = *dr;
-		*ddepp = dde;
-		ddt->cur_ddt_size += sizeof (dedup_entry_t);
-		ddt->ddt_count++;
-	}
-}
-
-/*
- * Using the specified dedup table, do a lookup for an entry with
- * the checksum cs.  If found, return the block's reference info
- * in *dr. Otherwise, insert a new entry in the dedup table, using
- * the reference information specified by *dr.
- *
- * return value:  true - entry was found
- *		  false - entry was not found
- */
-static boolean_t
-ddt_update(libzfs_handle_t *hdl, dedup_table_t *ddt, zio_cksum_t *cs,
-    uint64_t prop, dataref_t *dr)
-{
-	uint32_t hashcode;
-	dedup_entry_t **ddepp;
-
-	hashcode = BF64_GET(cs->zc_word[0], 0, ddt->numhashbits);
-
-	for (ddepp = &(ddt->dedup_hash_array[hashcode]); *ddepp != NULL;
-	    ddepp = &((*ddepp)->dde_next)) {
-		if (ZIO_CHECKSUM_EQUAL(((*ddepp)->dde_chksum), *cs) &&
-		    (*ddepp)->dde_prop == prop) {
-			*dr = (*ddepp)->dde_ref;
-			return (B_TRUE);
-		}
-	}
-	ddt_hash_append(hdl, ddt, ddepp, cs, prop, dr);
-	return (B_FALSE);
-}
-
 static int
 dump_record(dmu_replay_record_t *drr, void *payload, int payload_len,
     zio_cksum_t *zc, int outfd)
@@ -228,274 +114,6 @@ dump_record(dmu_replay_record_t *drr, void *payload, int payload_len,
 	return (0);
 }
 
-/*
- * This function is started in a separate thread when the dedup option
- * has been requested.  The main send thread determines the list of
- * snapshots to be included in the send stream and makes the ioctl calls
- * for each one.  But instead of having the ioctl send the output to the
- * the output fd specified by the caller of zfs_send()), the
- * ioctl is told to direct the output to a pipe, which is read by the
- * alternate thread running THIS function.  This function does the
- * dedup'ing by:
- *  1. building a dedup table (the DDT)
- *  2. doing checksums on each data block and inserting a record in the DDT
- *  3. looking for matching checksums, and
- *  4.  sending a DRR_WRITE_BYREF record instead of a write record whenever
- *      a duplicate block is found.
- * The output of this function then goes to the output fd requested
- * by the caller of zfs_send().
- */
-static void *
-cksummer(void *arg)
-{
-	dedup_arg_t *dda = arg;
-	char *buf = zfs_alloc(dda->dedup_hdl, SPA_MAXBLOCKSIZE);
-	dmu_replay_record_t thedrr = { 0 };
-	dmu_replay_record_t *drr = &thedrr;
-	FILE *ofp;
-	int outfd;
-	dedup_table_t ddt;
-	zio_cksum_t stream_cksum;
-	uint64_t numbuckets;
-
-#ifdef _ILP32
-	ddt.max_ddt_size = SMALLEST_POSSIBLE_MAX_DDT_MB << 20;
-#else
-	uint64_t physmem = sysconf(_SC_PHYS_PAGES) * sysconf(_SC_PAGESIZE);
-	ddt.max_ddt_size =
-	    MAX((physmem * MAX_DDT_PHYSMEM_PERCENT) / 100,
-	    SMALLEST_POSSIBLE_MAX_DDT_MB << 20);
-#endif
-
-	numbuckets = ddt.max_ddt_size / (sizeof (dedup_entry_t));
-
-	/*
-	 * numbuckets must be a power of 2.  Increase number to
-	 * a power of 2 if necessary.
-	 */
-	if (!ISP2(numbuckets))
-		numbuckets = 1ULL << high_order_bit(numbuckets);
-
-	ddt.dedup_hash_array = calloc(numbuckets, sizeof (dedup_entry_t *));
-	ddt.ddecache = umem_cache_create("dde", sizeof (dedup_entry_t), 0,
-	    NULL, NULL, NULL, NULL, NULL, 0);
-	ddt.cur_ddt_size = numbuckets * sizeof (dedup_entry_t *);
-	ddt.numhashbits = high_order_bit(numbuckets) - 1;
-	ddt.ddt_full = B_FALSE;
-
-	outfd = dda->outputfd;
-	ofp = fdopen(dda->inputfd, "r");
-	while (ssread(drr, sizeof (*drr), ofp) != 0) {
-
-		/*
-		 * kernel filled in checksum, we are going to write same
-		 * record, but need to regenerate checksum.
-		 */
-		if (drr->drr_type != DRR_BEGIN) {
-			bzero(&drr->drr_u.drr_checksum.drr_checksum,
-			    sizeof (drr->drr_u.drr_checksum.drr_checksum));
-		}
-
-		switch (drr->drr_type) {
-		case DRR_BEGIN:
-		{
-			struct drr_begin *drrb = &drr->drr_u.drr_begin;
-			int fflags;
-			int sz = 0;
-			ZIO_SET_CHECKSUM(&stream_cksum, 0, 0, 0, 0);
-
-			ASSERT3U(drrb->drr_magic, ==, DMU_BACKUP_MAGIC);
-
-			/* set the DEDUP feature flag for this stream */
-			fflags = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo);
-			fflags |= (DMU_BACKUP_FEATURE_DEDUP |
-			    DMU_BACKUP_FEATURE_DEDUPPROPS);
-			DMU_SET_FEATUREFLAGS(drrb->drr_versioninfo, fflags);
-
-			if (drr->drr_payloadlen != 0) {
-				sz = drr->drr_payloadlen;
-
-				if (sz > SPA_MAXBLOCKSIZE) {
-					buf = zfs_realloc(dda->dedup_hdl, buf,
-					    SPA_MAXBLOCKSIZE, sz);
-				}
-				(void) ssread(buf, sz, ofp);
-				if (ferror(stdin))
-					perror("fread");
-			}
-			if (dump_record(drr, buf, sz, &stream_cksum,
-			    outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_END:
-		{
-			struct drr_end *drre = &drr->drr_u.drr_end;
-			/* use the recalculated checksum */
-			drre->drr_checksum = stream_cksum;
-			if (dump_record(drr, NULL, 0, &stream_cksum,
-			    outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_OBJECT:
-		{
-			struct drr_object *drro = &drr->drr_u.drr_object;
-			if (drro->drr_bonuslen > 0) {
-				(void) ssread(buf,
-				    DRR_OBJECT_PAYLOAD_SIZE(drro), ofp);
-			}
-			if (dump_record(drr, buf, DRR_OBJECT_PAYLOAD_SIZE(drro),
-			    &stream_cksum, outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_SPILL:
-		{
-			struct drr_spill *drrs = &drr->drr_u.drr_spill;
-			(void) ssread(buf, DRR_SPILL_PAYLOAD_SIZE(drrs), ofp);
-			if (dump_record(drr, buf, DRR_SPILL_PAYLOAD_SIZE(drrs),
-			    &stream_cksum, outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_FREEOBJECTS:
-		{
-			if (dump_record(drr, NULL, 0, &stream_cksum,
-			    outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_WRITE:
-		{
-			struct drr_write *drrw = &drr->drr_u.drr_write;
-			dataref_t	dataref;
-			uint64_t	payload_size;
-
-			payload_size = DRR_WRITE_PAYLOAD_SIZE(drrw);
-			(void) ssread(buf, payload_size, ofp);
-
-			/*
-			 * Use the existing checksum if it's dedup-capable,
-			 * else calculate a SHA256 checksum for it.
-			 */
-
-			if (ZIO_CHECKSUM_EQUAL(drrw->drr_key.ddk_cksum,
-			    zero_cksum) ||
-			    !DRR_IS_DEDUP_CAPABLE(drrw->drr_flags)) {
-				SHA2_CTX ctx;
-				zio_cksum_t tmpsha256;
-
-				SHA2Init(SHA256, &ctx);
-				SHA2Update(&ctx, buf, payload_size);
-				SHA2Final(&tmpsha256, &ctx);
-
-				drrw->drr_key.ddk_cksum.zc_word[0] =
-				    BE_64(tmpsha256.zc_word[0]);
-				drrw->drr_key.ddk_cksum.zc_word[1] =
-				    BE_64(tmpsha256.zc_word[1]);
-				drrw->drr_key.ddk_cksum.zc_word[2] =
-				    BE_64(tmpsha256.zc_word[2]);
-				drrw->drr_key.ddk_cksum.zc_word[3] =
-				    BE_64(tmpsha256.zc_word[3]);
-				drrw->drr_checksumtype = ZIO_CHECKSUM_SHA256;
-				drrw->drr_flags |= DRR_CHECKSUM_DEDUP;
-			}
-
-			dataref.ref_guid = drrw->drr_toguid;
-			dataref.ref_object = drrw->drr_object;
-			dataref.ref_offset = drrw->drr_offset;
-
-			if (ddt_update(dda->dedup_hdl, &ddt,
-			    &drrw->drr_key.ddk_cksum, drrw->drr_key.ddk_prop,
-			    &dataref)) {
-				dmu_replay_record_t wbr_drr = {0};
-				struct drr_write_byref *wbr_drrr =
-				    &wbr_drr.drr_u.drr_write_byref;
-
-				/* block already present in stream */
-				wbr_drr.drr_type = DRR_WRITE_BYREF;
-
-				wbr_drrr->drr_object = drrw->drr_object;
-				wbr_drrr->drr_offset = drrw->drr_offset;
-				wbr_drrr->drr_length = drrw->drr_logical_size;
-				wbr_drrr->drr_toguid = drrw->drr_toguid;
-				wbr_drrr->drr_refguid = dataref.ref_guid;
-				wbr_drrr->drr_refobject =
-				    dataref.ref_object;
-				wbr_drrr->drr_refoffset =
-				    dataref.ref_offset;
-
-				wbr_drrr->drr_checksumtype =
-				    drrw->drr_checksumtype;
-				wbr_drrr->drr_flags = drrw->drr_flags;
-				wbr_drrr->drr_key.ddk_cksum =
-				    drrw->drr_key.ddk_cksum;
-				wbr_drrr->drr_key.ddk_prop =
-				    drrw->drr_key.ddk_prop;
-
-				if (dump_record(&wbr_drr, NULL, 0,
-				    &stream_cksum, outfd) != 0)
-					goto out;
-			} else {
-				/* block not previously seen */
-				if (dump_record(drr, buf, payload_size,
-				    &stream_cksum, outfd) != 0)
-					goto out;
-			}
-			break;
-		}
-
-		case DRR_WRITE_EMBEDDED:
-		{
-			struct drr_write_embedded *drrwe =
-			    &drr->drr_u.drr_write_embedded;
-			(void) ssread(buf,
-			    P2ROUNDUP((uint64_t)drrwe->drr_psize, 8), ofp);
-			if (dump_record(drr, buf,
-			    P2ROUNDUP((uint64_t)drrwe->drr_psize, 8),
-			    &stream_cksum, outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_FREE:
-		{
-			if (dump_record(drr, NULL, 0, &stream_cksum,
-			    outfd) != 0)
-				goto out;
-			break;
-		}
-
-		case DRR_OBJECT_RANGE:
-		{
-			if (dump_record(drr, NULL, 0, &stream_cksum,
-			    outfd) != 0)
-				goto out;
-			break;
-		}
-
-		default:
-			(void) fprintf(stderr, "INVALID record type 0x%x\n",
-			    drr->drr_type);
-			/* should never happen, so assert */
-			assert(B_FALSE);
-		}
-	}
-out:
-	umem_cache_destroy(ddt.ddecache);
-	free(ddt.dedup_hash_array);
-	free(buf);
-	(void) fclose(ofp);
-
-	return (NULL);
-}
-
 /*
  * Routines for dealing with the AVL tree of fs-nvlists
  */
@@ -2478,7 +2096,6 @@ zfs_send(zfs_handle_t *zhp, const char *fromsnap, const char *tosnap,
 	int spa_version;
 	pthread_t tid = 0;
 	int pipefd[2];
-	dedup_arg_t dda = { 0 };
 	int featureflags = 0;
 	FILE *fout;
 
@@ -2502,33 +2119,6 @@ zfs_send(zfs_handle_t *zhp, const char *fromsnap, const char *tosnap,
 	if (flags->holds)
 		featureflags |= DMU_BACKUP_FEATURE_HOLDS;
 
-	/*
-	 * Start the dedup thread if this is a dedup stream. We do not bother
-	 * doing this if this a raw send of an encrypted dataset with dedup off
-	 * because normal encrypted blocks won't dedup.
-	 */
-	if (flags->dedup && !flags->dryrun && !(flags->raw &&
-	    zfs_prop_get_int(zhp, ZFS_PROP_ENCRYPTION) != ZIO_CRYPT_OFF &&
-	    zfs_prop_get_int(zhp, ZFS_PROP_DEDUP) == ZIO_CHECKSUM_OFF)) {
-		featureflags |= (DMU_BACKUP_FEATURE_DEDUP |
-		    DMU_BACKUP_FEATURE_DEDUPPROPS);
-		if ((err = socketpair(AF_UNIX, SOCK_STREAM, 0, pipefd)) != 0) {
-			zfs_error_aux(zhp->zfs_hdl, strerror(errno));
-			return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED,
-			    errbuf));
-		}
-		dda.outputfd = outfd;
-		dda.inputfd = pipefd[1];
-		dda.dedup_hdl = zhp->zfs_hdl;
-		if ((err = pthread_create(&tid, NULL, cksummer, &dda)) != 0) {
-			(void) close(pipefd[0]);
-			(void) close(pipefd[1]);
-			zfs_error_aux(zhp->zfs_hdl, strerror(errno));
-			return (zfs_error(zhp->zfs_hdl,
-			    EZFS_THREADCREATEFAILED, errbuf));
-		}
-	}
-
 	if (flags->replicate || flags->doall || flags->props ||
 	    flags->holds || flags->backup) {
 		char full_tosnap_name[ZFS_MAX_DATASET_NAME_LEN];
@@ -2706,34 +2296,6 @@ zfs_send(zfs_handle_t *zhp, const char *fromsnap, const char *tosnap,
 	return (err);
 }
 
-static int
-get_dedup_fd(zfs_handle_t *zhp, dedup_arg_t *dda, int fd, pthread_t *tid,
-    int *outfd)
-{
-	int pipefd[2];
-	char errbuf[1024];
-	int err;
-	(void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
-	    "warning: cannot send '%s'"), zhp->zfs_name);
-	if ((err = socketpair(AF_UNIX, SOCK_STREAM, 0, pipefd)) != 0) {
-		zfs_error_aux(zhp->zfs_hdl, strerror(errno));
-		return (zfs_error(zhp->zfs_hdl, EZFS_PIPEFAILED,
-		    errbuf));
-	}
-	dda->outputfd = fd;
-	dda->inputfd = pipefd[1];
-	dda->dedup_hdl = zhp->zfs_hdl;
-	if ((err = pthread_create(tid, NULL, cksummer, dda)) != 0) {
-		(void) close(pipefd[0]);
-		(void) close(pipefd[1]);
-		zfs_error_aux(zhp->zfs_hdl, strerror(err));
-		return (zfs_error(zhp->zfs_hdl, EZFS_THREADCREATEFAILED,
-		    errbuf));
-	}
-	*outfd = pipefd[0];
-	return (0);
-}
-
 zfs_handle_t *
 name_to_dir_handle(libzfs_handle_t *hdl, const char *snapname)
 {
@@ -2819,9 +2381,8 @@ zfs_send_one(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 	libzfs_handle_t *hdl = zhp->zfs_hdl;
 	char *name = zhp->zfs_name;
 	int orig_fd = fd;
-	pthread_t ddtid, ptid;
+	pthread_t ptid;
 	progress_arg_t pa = { 0 };
-	dedup_arg_t dda = { 0 };
 
 	char errbuf[1024];
 	(void) snprintf(errbuf, sizeof (errbuf), dgettext(TEXT_DOMAIN,
@@ -2914,16 +2475,6 @@ zfs_send_one(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 	if (flags->dryrun)
 		return (0);
 
-	/*
-	 * If deduplication is requested, spawn a thread that will deduplicate
-	 * the data coming out of the kernel.
-	 */
-	if (flags->dedup) {
-		err = get_dedup_fd(zhp, &dda, fd, &ddtid, &fd);
-		if (err != 0)
-			return (err);
-	}
-
 	/*
 	 * If progress reporting is requested, spawn a new thread to poll
 	 * ZFS_IOC_SEND_PROGRESS at a regular interval.
@@ -2939,11 +2490,6 @@ zfs_send_one(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 		    send_progress_thread, &pa);
 		if (err != 0) {
 			zfs_error_aux(zhp->zfs_hdl, strerror(errno));
-			if (flags->dedup) {
-				(void) pthread_cancel(ddtid);
-				(void) close(fd);
-				(void) pthread_join(ddtid, NULL);
-			}
 			return (zfs_error(zhp->zfs_hdl,
 			    EZFS_THREADCREATEFAILED, errbuf));
 		}
@@ -2966,12 +2512,6 @@ zfs_send_one(zfs_handle_t *zhp, const char *from, int fd, sendflags_t *flags,
 			return (zfs_standard_error(hdl, error, errbuf));
 		}
 	}
-	if (flags->dedup) {
-		if (err != 0)
-			(void) pthread_cancel(ddtid);
-		(void) close(fd);
-		(void) pthread_join(ddtid, NULL);
-	}
 
 	if (flags->props || flags->holds || flags->backup) {
 		/* Write the final end record. */
@@ -3965,8 +3505,7 @@ recv_incremental_replication(libzfs_handle_t *hdl, const char *tofs,
 static int
 zfs_receive_package(libzfs_handle_t *hdl, int fd, const char *destname,
     recvflags_t *flags, dmu_replay_record_t *drr, zio_cksum_t *zc,
-    char **top_zfs, int cleanup_fd, uint64_t *action_handlep,
-    nvlist_t *cmdprops)
+    char **top_zfs, nvlist_t *cmdprops)
 {
 	nvlist_t *stream_nv = NULL;
 	avl_tree_t *stream_avl = NULL;
@@ -4143,8 +3682,7 @@ zfs_receive_package(libzfs_handle_t *hdl, int fd, const char *destname,
 		 * recv_skip() and return 0).
 		 */
 		error = zfs_receive_impl(hdl, destname, NULL, flags, fd,
-		    sendfs, stream_nv, stream_avl, top_zfs, cleanup_fd,
-		    action_handlep, sendsnap, cmdprops);
+		    sendfs, stream_nv, stream_avl, top_zfs, sendsnap, cmdprops);
 		if (error == ENODATA) {
 			error = 0;
 			break;
@@ -4530,8 +4068,8 @@ static int
 zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
     const char *originsnap, recvflags_t *flags, dmu_replay_record_t *drr,
     dmu_replay_record_t *drr_noswap, const char *sendfs, nvlist_t *stream_nv,
-    avl_tree_t *stream_avl, char **top_zfs, int cleanup_fd,
-    uint64_t *action_handlep, const char *finalsnap, nvlist_t *cmdprops)
+    avl_tree_t *stream_avl, char **top_zfs,
+    const char *finalsnap, nvlist_t *cmdprops)
 {
 	time_t begin_time;
 	int ioctl_err, ioctl_errno, err;
@@ -4741,24 +4279,16 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 			(void) printf("found clone origin %s\n", origin);
 	}
 
-	if (!hdl->libzfs_dedup_warning_printed &&
-	    (DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
+	if ((DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
 	    DMU_BACKUP_FEATURE_DEDUP)) {
 		(void) fprintf(stderr,
-		    gettext("WARNING: This is a deduplicated send stream.  "
-		    "The ability to send and\n"
-		    "receive deduplicated send streams is deprecated.  "
-		    "In the future, the\n"
-		    "ability to receive a deduplicated send stream with "
-		    "\"zfs receive\" will be\n"
-		    "removed. However, in the future, a utility will be "
-		    "provided to convert a\n"
-		    "deduplicated send stream to a regular "
-		    "(non-deduplicated) stream. This\n"
-		    "future utility will require that the send stream be "
-		    "located in a\n"
-		    "seek-able file, rather than provided by a pipe.\n\n"));
-		hdl->libzfs_dedup_warning_printed = B_TRUE;
+		    gettext("ERROR: \"zfs receive\" no longer supports "
+		    "deduplicated send streams.  Use\n"
+		    "the \"zstream redup\" command to convert this stream "
+		    "to a regular,\n"
+		    "non-deduplicated stream.\n"));
+		err = zfs_error(hdl, EZFS_NOTSUP, errbuf);
+		goto out;
 	}
 
 	boolean_t resuming = DMU_GET_FEATUREFLAGS(drrb->drr_versioninfo) &
@@ -5103,8 +4633,8 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 
 	err = ioctl_err = lzc_receive_with_cmdprops(destsnap, rcvprops,
 	    oxprops, wkeydata, wkeylen, origin, flags->force, flags->resumable,
-	    raw, infd, drr_noswap, cleanup_fd, &read_bytes, &errflags,
-	    action_handlep, &prop_errors);
+	    raw, infd, drr_noswap, -1, &read_bytes, &errflags,
+	    NULL, &prop_errors);
 	ioctl_errno = ioctl_err;
 	prop_errflags = errflags;
 
@@ -5435,8 +4965,8 @@ zfs_receive_checkprops(libzfs_handle_t *hdl, nvlist_t *props,
 static int
 zfs_receive_impl(libzfs_handle_t *hdl, const char *tosnap,
     const char *originsnap, recvflags_t *flags, int infd, const char *sendfs,
-    nvlist_t *stream_nv, avl_tree_t *stream_avl, char **top_zfs, int cleanup_fd,
-    uint64_t *action_handlep, const char *finalsnap, nvlist_t *cmdprops)
+    nvlist_t *stream_nv, avl_tree_t *stream_avl, char **top_zfs,
+    const char *finalsnap, nvlist_t *cmdprops)
 {
 	int err;
 	dmu_replay_record_t drr, drr_noswap;
@@ -5546,12 +5076,12 @@ zfs_receive_impl(libzfs_handle_t *hdl, const char *tosnap,
 		}
 		return (zfs_receive_one(hdl, infd, tosnap, originsnap, flags,
 		    &drr, &drr_noswap, sendfs, stream_nv, stream_avl, top_zfs,
-		    cleanup_fd, action_handlep, finalsnap, cmdprops));
+		    finalsnap, cmdprops));
 	} else {
 		assert(DMU_GET_STREAM_HDRTYPE(drrb->drr_versioninfo) ==
 		    DMU_COMPOUNDSTREAM);
 		return (zfs_receive_package(hdl, infd, tosnap, flags, &drr,
-		    &zcksum, top_zfs, cleanup_fd, action_handlep, cmdprops));
+		    &zcksum, top_zfs, cmdprops));
 	}
 }
 
@@ -5568,8 +5098,6 @@ zfs_receive(libzfs_handle_t *hdl, const char *tosnap, nvlist_t *props,
 {
 	char *top_zfs = NULL;
 	int err;
-	int cleanup_fd;
-	uint64_t action_handle = 0;
 	struct stat sb;
 	char *originsnap = NULL;
 
@@ -5595,13 +5123,8 @@ zfs_receive(libzfs_handle_t *hdl, const char *tosnap, nvlist_t *props,
 			return (err);
 	}
 
-	cleanup_fd = open(ZFS_DEV, O_RDWR);
-	VERIFY(cleanup_fd >= 0);
-
 	err = zfs_receive_impl(hdl, tosnap, originsnap, flags, infd, NULL, NULL,
-	    stream_avl, &top_zfs, cleanup_fd, &action_handle, NULL, props);
-
-	VERIFY(0 == close(cleanup_fd));
+	    stream_avl, &top_zfs, NULL, props);
 
 	if (err == 0 && !flags->nomount && flags->domount && top_zfs) {
 		zfs_handle_t *zhp = NULL;
diff --git a/lib/libzfs_core/libzfs_core.c b/lib/libzfs_core/libzfs_core.c
index 18143d364086..4e83b624b261 100644
--- a/lib/libzfs_core/libzfs_core.c
+++ b/lib/libzfs_core/libzfs_core.c
@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
  * Copyright 2017 RackTop Systems.
@@ -783,9 +783,8 @@ static int
 recv_impl(const char *snapname, nvlist_t *recvdprops, nvlist_t *localprops,
     uint8_t *wkeydata, uint_t wkeylen, const char *origin, boolean_t force,
     boolean_t resumable, boolean_t raw, int input_fd,
-    const dmu_replay_record_t *begin_record, int cleanup_fd,
-    uint64_t *read_bytes, uint64_t *errflags, uint64_t *action_handle,
-    nvlist_t **errors)
+    const dmu_replay_record_t *begin_record, uint64_t *read_bytes,
+    uint64_t *errflags, nvlist_t **errors)
 {
 	dmu_replay_record_t drr;
 	char fsname[MAXPATHLEN];
@@ -868,12 +867,6 @@ recv_impl(const char *snapname, nvlist_t *recvdprops, nvlist_t *localprops,
 		if (resumable)
 			fnvlist_add_boolean(innvl, "resumable");
 
-		if (cleanup_fd >= 0)
-			fnvlist_add_int32(innvl, "cleanup_fd", cleanup_fd);
-
-		if (action_handle != NULL)
-			fnvlist_add_uint64(innvl, "action_handle",
-			    *action_handle);
 
 		error = lzc_ioctl(ZFS_IOC_RECV_NEW, fsname, innvl, &outnvl);
 
@@ -885,10 +878,6 @@ recv_impl(const char *snapname, nvlist_t *recvdprops, nvlist_t *localprops,
 			error = nvlist_lookup_uint64(outnvl, "error_flags",
 			    errflags);
 
-		if (error == 0 && action_handle != NULL)
-			error = nvlist_lookup_uint64(outnvl, "action_handle",
-			    action_handle);
-
 		if (error == 0 && errors != NULL) {
 			nvlist_t *nvl;
 			error = nvlist_lookup_nvlist(outnvl, "errors", &nvl);
@@ -931,12 +920,6 @@ recv_impl(const char *snapname, nvlist_t *recvdprops, nvlist_t *localprops,
 		zc.zc_cleanup_fd = -1;
 		zc.zc_action_handle = 0;
 
-		if (cleanup_fd >= 0)
-			zc.zc_cleanup_fd = cleanup_fd;
-
-		if (action_handle != NULL)
-			zc.zc_action_handle = *action_handle;
-
 		zc.zc_nvlist_dst_size = 128 * 1024;
 		zc.zc_nvlist_dst = (uint64_t)(uintptr_t)
 		    malloc(zc.zc_nvlist_dst_size);
@@ -951,9 +934,6 @@ recv_impl(const char *snapname, nvlist_t *recvdprops, nvlist_t *localprops,
 			if (errflags != NULL)
 				*errflags = zc.zc_obj;
 
-			if (action_handle != NULL)
-				*action_handle = zc.zc_action_handle;
-
 			if (errors != NULL)
 				VERIFY0(nvlist_unpack(
 				    (void *)(uintptr_t)zc.zc_nvlist_dst,
@@ -986,7 +966,7 @@ lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
     boolean_t force, boolean_t raw, int fd)
 {
 	return (recv_impl(snapname, props, NULL, NULL, 0, origin, force,
-	    B_FALSE, raw, fd, NULL, -1, NULL, NULL, NULL, NULL));
+	    B_FALSE, raw, fd, NULL, NULL, NULL, NULL));
 }
 
 /*
@@ -1000,7 +980,7 @@ lzc_receive_resumable(const char *snapname, nvlist_t *props, const char *origin,
     boolean_t force, boolean_t raw, int fd)
 {
 	return (recv_impl(snapname, props, NULL, NULL, 0, origin, force,
-	    B_TRUE, raw, fd, NULL, -1, NULL, NULL, NULL, NULL));
+	    B_TRUE, raw, fd, NULL, NULL, NULL, NULL));
 }
 
 /*
@@ -1023,7 +1003,7 @@ lzc_receive_with_header(const char *snapname, nvlist_t *props,
 		return (EINVAL);
 
 	return (recv_impl(snapname, props, NULL, NULL, 0, origin, force,
-	    resumable, raw, fd, begin_record, -1, NULL, NULL, NULL, NULL));
+	    resumable, raw, fd, begin_record, NULL, NULL, NULL));
 }
 
 /*
@@ -1039,9 +1019,7 @@ lzc_receive_with_header(const char *snapname, nvlist_t *props,
  * The 'errflags' value will contain zprop_errflags_t flags which are
  * used to describe any failures.
  *
- * The 'action_handle' is used to pass the handle for this guid/ds mapping.
- * It should be set to zero on first call and will contain an updated handle
- * on success, it should be passed in subsequent calls.
+ * The 'action_handle' and 'cleanup_fd' are no longer used, and are ignored.
  *
  * The 'errors' nvlist contains an entry for each unapplied received
  * property.  Callers are responsible for freeing this nvlist.
@@ -1053,8 +1031,8 @@ int lzc_receive_one(const char *snapname, nvlist_t *props,
     nvlist_t **errors)
 {
 	return (recv_impl(snapname, props, NULL, NULL, 0, origin, force,
-	    resumable, raw, input_fd, begin_record, cleanup_fd, read_bytes,
-	    errflags, action_handle, errors));
+	    resumable, raw, input_fd, begin_record,
+	    read_bytes, errflags, errors));
 }
 
 /*
@@ -1073,8 +1051,8 @@ int lzc_receive_with_cmdprops(const char *snapname, nvlist_t *props,
     nvlist_t **errors)
 {
 	return (recv_impl(snapname, props, cmdprops, wkeydata, wkeylen, origin,
-	    force, resumable, raw, input_fd, begin_record, cleanup_fd,
-	    read_bytes, errflags, action_handle, errors));
+	    force, resumable, raw, input_fd, begin_record,
+	    read_bytes, errflags, errors));
 }
 
 /*
diff --git a/man/man8/zfs-receive.8 b/man/man8/zfs-receive.8
index a60a5c7bbb61..2d799a2da697 100644
--- a/man/man8/zfs-receive.8
+++ b/man/man8/zfs-receive.8
@@ -105,17 +105,11 @@ destroyed by using the
 .Nm zfs Cm destroy Fl d
 command.
 .Pp
-Deduplicated send streams can be generated by using the
-.Nm zfs Cm send Fl D
+The ability to send and receive deduplicated send streams has been removed.
+However, a deduplicated send stream created with older software can be converted
+to a regular (non-deduplicated) stream by using the
+.Nm zstream Cm redup
 command.
-\fBThe ability to send and receive deduplicated send streams is deprecated.\fR
-In the future, the ability to receive a deduplicated send stream with
-.Nm zfs Cm receive
-will be removed.
-However, in the future, a utility will be provided to convert a
-deduplicated send stream to a regular (non-deduplicated) stream.
-This future utility will require that the send stream be located in a
-seek-able file, rather than provided by a pipe.
 .Pp
 If
 .Fl o Em property Ns = Ns Ar value
@@ -378,3 +372,4 @@ deleting its saved partially received state.
 .El
 .Sh SEE ALSO
 .Xr zfs-send 8
+.Xr zstream 8
diff --git a/man/man8/zfs-send.8 b/man/man8/zfs-send.8
index 1deedc214bb8..c1b2134d1180 100644
--- a/man/man8/zfs-send.8
+++ b/man/man8/zfs-send.8
@@ -86,21 +86,9 @@ The output can be redirected to a file or to a different system
 By default, a full stream is generated.
 .Bl -tag -width "-D"
 .It Fl D, -dedup
-Generate a deduplicated stream.
-\fBDeduplicated send is deprecated and will be removed in a future release.\fR
-(In the future, the flag will be accepted but a regular, non-deduplicated
-stream will be generated.)
-Blocks which would have been sent multiple times in the send stream will only be
-sent once.
-The receiving system must also support this feature to receive a deduplicated
-stream.
-This flag can be used regardless of the dataset's
-.Sy dedup
-property, but performance will be much better if the filesystem uses a
-dedup-capable checksum
-.Po for example,
-.Sy sha256
-.Pc .
+Deduplicated send is no longer supported.
+This flag is accepted for backwards compatibility, but a regular,
+non-deduplicated stream will be generated.
 .It Fl I Ar snapshot
 Generate a stream package that sends all intermediary snapshots from the first
 snapshot to the second snapshot.
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 6eb935720f47..a21ac8d74a47 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  * Copyright (c) 2013, Joyent, Inc. All rights reserved.
  * Copyright (c) 2016, Nexenta Systems, Inc. All rights reserved.
@@ -1560,56 +1560,6 @@ dmu_return_arcbuf(arc_buf_t *buf)
 	arc_buf_destroy(buf, FTAG);
 }
 
-void
-dmu_copy_from_buf(objset_t *os, uint64_t object, uint64_t offset,
-    dmu_buf_t *handle, dmu_tx_t *tx)
-{
-	dmu_buf_t *dst_handle;
-	dmu_buf_impl_t *dstdb;
-	dmu_buf_impl_t *srcdb = (dmu_buf_impl_t *)handle;
-	dmu_object_type_t type;
-	arc_buf_t *abuf;
-	uint64_t datalen;
-	boolean_t byteorder;
-	uint8_t salt[ZIO_DATA_SALT_LEN];
-	uint8_t iv[ZIO_DATA_IV_LEN];
-	uint8_t mac[ZIO_DATA_MAC_LEN];
-
-	ASSERT3P(srcdb->db_buf, !=, NULL);
-
-	/* hold the db that we want to write to */
-	VERIFY0(dmu_buf_hold(os, object, offset, FTAG, &dst_handle,
-	    DMU_READ_NO_DECRYPT));
-	dstdb = (dmu_buf_impl_t *)dst_handle;
-	datalen = arc_buf_size(srcdb->db_buf);
-
-	DB_DNODE_ENTER(dstdb);
-	type = DB_DNODE(dstdb)->dn_type;
-	DB_DNODE_EXIT(dstdb);
-
-	/* allocated an arc buffer that matches the type of srcdb->db_buf */
-	if (arc_is_encrypted(srcdb->db_buf)) {
-		arc_get_raw_params(srcdb->db_buf, &byteorder, salt, iv, mac);
-		abuf = arc_loan_raw_buf(os->os_spa, dmu_objset_id(os),
-		    byteorder, salt, iv, mac, type,
-		    datalen, arc_buf_lsize(srcdb->db_buf),
-		    arc_get_compression(srcdb->db_buf));
-	} else {
-		/* we won't get a compressed db back from dmu_buf_hold() */
-		ASSERT3U(arc_get_compression(srcdb->db_buf),
-		    ==, ZIO_COMPRESS_OFF);
-		abuf = arc_loan_buf(os->os_spa,
-		    DMU_OT_IS_METADATA(type), datalen);
-	}
-
-	ASSERT3U(datalen, ==, arc_buf_size(abuf));
-
-	/* copy the data to the new buffer and assign it to the dstdb */
-	bcopy(srcdb->db_buf->b_data, abuf->b_data, datalen);
-	dbuf_assign_arcbuf(dstdb, abuf, tx);
-	dmu_buf_rele(dst_handle, FTAG);
-}
-
 /*
  * When possible directly assign passed loaned arc buffer to a dbuf.
  * If this is not possible copy the contents of passed arc buf via
diff --git a/module/zfs/dmu_recv.c b/module/zfs/dmu_recv.c
index 9c82cecc6a15..817c85b935ba 100644
--- a/module/zfs/dmu_recv.c
+++ b/module/zfs/dmu_recv.c
@@ -21,7 +21,7 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2014, Joyent, Inc. All rights reserved.
  * Copyright 2014 HybridCluster. All rights reserved.
  * Copyright (c) 2018, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
@@ -101,8 +101,6 @@ struct receive_writer_arg {
 	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;
 	boolean_t raw;   /* DMU_BACKUP_FEATURE_RAW set */
 	boolean_t spill; /* DRR_FLAG_SPILL_BLOCK set */
@@ -123,13 +121,6 @@ struct receive_writer_arg {
 	boolean_t or_byteorder;
 };
 
-typedef struct guid_map_entry {
-	uint64_t	guid;
-	boolean_t	raw;
-	objset_t	*gme_os;
-	avl_node_t	avlnode;
-} guid_map_entry_t;
-
 typedef struct dmu_recv_begin_arg {
 	const char *drba_origin;
 	dmu_recv_cookie_t *drba_cookie;
@@ -1212,38 +1203,6 @@ dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
 	return (err);
 }
 
-static int
-guid_compare(const void *arg1, const void *arg2)
-{
-	const guid_map_entry_t *gmep1 = (const guid_map_entry_t *)arg1;
-	const guid_map_entry_t *gmep2 = (const guid_map_entry_t *)arg2;
-
-	return (TREE_CMP(gmep1->guid, gmep2->guid));
-}
-
-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) {
-		ds_hold_flags_t dsflags = DS_HOLD_FLAG_DECRYPT;
-
-		if (gmep->raw) {
-			gmep->gme_os->os_raw_receive = B_FALSE;
-			dsflags &= ~DS_HOLD_FLAG_DECRYPT;
-		}
-
-		dsl_dataset_disown(gmep->gme_os->os_dsl_dataset,
-		    dsflags, gmep);
-		kmem_free(gmep, sizeof (guid_map_entry_t));
-	}
-	avl_destroy(ca);
-	kmem_free(ca, sizeof (avl_tree_t));
-}
-
 static int
 receive_read(dmu_recv_cookie_t *drc, int len, void *buf)
 {
@@ -1845,81 +1804,6 @@ receive_process_write_record(struct receive_writer_arg *rwa,
 	return (EAGAIN);
 }
 
-/*
- * 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.
- */
-noinline 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;
-	int flags = DMU_READ_PREFETCH;
-	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));
-		}
-		ref_os = gmep->gme_os;
-	} else {
-		ref_os = rwa->os;
-	}
-
-	if (drrwbr->drr_object > rwa->max_object)
-		rwa->max_object = drrwbr->drr_object;
-
-	if (rwa->raw)
-		flags |= DMU_READ_NO_DECRYPT;
-
-	/* may return either a regular db or an encrypted one */
-	err = dmu_buf_hold(ref_os, drrwbr->drr_refobject,
-	    drrwbr->drr_refoffset, FTAG, &dbp, flags);
-	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);
-	}
-
-	if (rwa->raw) {
-		dmu_copy_from_buf(rwa->os, drrwbr->drr_object,
-		    drrwbr->drr_offset, dbp, tx);
-	} else {
-		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)
@@ -2607,13 +2491,6 @@ receive_process_record(struct receive_writer_arg *rwa,
 		}
 		break;
 	}
-	case DRR_WRITE_BYREF:
-	{
-		struct drr_write_byref *drrwbr =
-		    &rrd->header.drr_u.drr_write_byref;
-		err = receive_write_byref(rwa, drrwbr);
-		break;
-	}
 	case DRR_WRITE_EMBEDDED:
 	{
 		struct drr_write_embedded *drrwe =
@@ -2754,8 +2631,7 @@ resume_check(dmu_recv_cookie_t *drc, nvlist_t *begin_nvl)
  * NB: callers *must* call dmu_recv_end() if this succeeds.
  */
 int
-dmu_recv_stream(dmu_recv_cookie_t *drc, int cleanup_fd,
-    uint64_t *action_handlep, offset_t *voffp)
+dmu_recv_stream(dmu_recv_cookie_t *drc, offset_t *voffp)
 {
 	int err = 0;
 	struct receive_writer_arg *rwa = kmem_zalloc(sizeof (*rwa), KM_SLEEP);
@@ -2779,41 +2655,6 @@ dmu_recv_stream(dmu_recv_cookie_t *drc, int cleanup_fd,
 	ASSERT0(drc->drc_os->os_encrypted &&
 	    (drc->drc_featureflags & DMU_BACKUP_FEATURE_EMBED_DATA));
 
-	/* if this stream is dedup'ed, set up the avl tree for guid mapping */
-	if (drc->drc_featureflags & DMU_BACKUP_FEATURE_DEDUP) {
-		minor_t minor;
-
-		if (cleanup_fd == -1) {
-			err = SET_ERROR(EBADF);
-			goto out;
-		}
-		err = zfs_onexit_fd_hold(cleanup_fd, &minor);
-		if (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 (err != 0)
-				goto out;
-		} else {
-			err = zfs_onexit_cb_data(minor, *action_handlep,
-			    (void **)&rwa->guid_to_ds_map);
-			if (err != 0)
-				goto out;
-		}
-
-		drc->drc_guid_to_ds_map = rwa->guid_to_ds_map;
-	}
-
 	/* handle DSL encryption key payload */
 	if (drc->drc_featureflags & DMU_BACKUP_FEATURE_RAW) {
 		nvlist_t *keynvl = NULL;
@@ -2980,9 +2821,6 @@ dmu_recv_stream(dmu_recv_cookie_t *drc, int cleanup_fd,
 
 	kmem_free(rwa, sizeof (*rwa));
 	nvlist_free(drc->drc_begin_nvl);
-	if ((drc->drc_featureflags & DMU_BACKUP_FEATURE_DEDUP) &&
-	    (cleanup_fd != -1))
-		zfs_onexit_fd_rele(cleanup_fd);
 
 	if (err != 0) {
 		/*
@@ -3083,6 +2921,7 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 	dmu_recv_cookie_t *drc = arg;
 	dsl_pool_t *dp = dmu_tx_pool(tx);
 	boolean_t encrypted = drc->drc_ds->ds_dir->dd_crypto_obj != 0;
+	uint64_t newsnapobj;
 
 	spa_history_log_internal_ds(drc->drc_ds, "finish receiving",
 	    tx, "snap=%s", drc->drc_tosnap);
@@ -3148,7 +2987,7 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 		dsl_dataset_phys(origin_head)->ds_flags &=
 		    ~DS_FLAG_INCONSISTENT;
 
-		drc->drc_newsnapobj =
+		newsnapobj =
 		    dsl_dataset_phys(origin_head)->ds_prev_snap_obj;
 
 		dsl_dataset_rele(origin_head, FTAG);
@@ -3188,7 +3027,7 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 			(void) zap_remove(dp->dp_meta_objset, ds->ds_object,
 			    DS_FIELD_RESUME_REDACT_BOOKMARK_SNAPS, tx);
 		}
-		drc->drc_newsnapobj =
+		newsnapobj =
 		    dsl_dataset_phys(drc->drc_ds)->ds_prev_snap_obj;
 	}
 
@@ -3203,9 +3042,9 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 	 * value.
 	 */
 	if (drc->drc_raw && drc->drc_ivset_guid != 0) {
-		dmu_object_zapify(dp->dp_meta_objset, drc->drc_newsnapobj,
+		dmu_object_zapify(dp->dp_meta_objset, newsnapobj,
 		    DMU_OT_DSL_DATASET, tx);
-		VERIFY0(zap_update(dp->dp_meta_objset, drc->drc_newsnapobj,
+		VERIFY0(zap_update(dp->dp_meta_objset, newsnapobj,
 		    DS_FIELD_IVSET_GUID, sizeof (uint64_t), 1,
 		    &drc->drc_ivset_guid, tx));
 	}
@@ -3226,54 +3065,6 @@ dmu_recv_end_sync(void *arg, dmu_tx_t *tx)
 	drc->drc_ds = NULL;
 }
 
-static int
-add_ds_to_guidmap(const char *name, avl_tree_t *guid_map, uint64_t snapobj,
-    boolean_t raw)
-{
-	dsl_pool_t *dp;
-	dsl_dataset_t *snapds;
-	guid_map_entry_t *gmep;
-	objset_t *os;
-	ds_hold_flags_t dsflags = (raw) ? 0 : DS_HOLD_FLAG_DECRYPT;
-	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_own_obj(dp, snapobj, dsflags, gmep, &snapds);
-
-	if (err == 0) {
-		err = dmu_objset_from_ds(snapds, &os);
-		if (err != 0) {
-			dsl_dataset_disown(snapds, dsflags, FTAG);
-			dsl_pool_rele(dp, FTAG);
-			kmem_free(gmep, sizeof (*gmep));
-			return (err);
-		}
-		/*
-		 * If this is a deduplicated raw send stream, we need
-		 * to make sure that we can still read raw blocks from
-		 * earlier datasets in the stream, so we set the
-		 * os_raw_receive flag now.
-		 */
-		if (raw)
-			os->os_raw_receive = B_TRUE;
-
-		gmep->raw = raw;
-		gmep->guid = dsl_dataset_phys(snapds)->ds_guid;
-		gmep->gme_os = os;
-		avl_add(guid_map, gmep);
-	} else {
-		kmem_free(gmep, sizeof (*gmep));
-	}
-
-	dsl_pool_rele(dp, FTAG);
-	return (err);
-}
-
 static int dmu_recv_end_modified_blocks = 3;
 
 static int
@@ -3325,12 +3116,6 @@ dmu_recv_end(dmu_recv_cookie_t *drc, void *owner)
 		    drc->drc_tofs, drc->drc_tosnap);
 		zvol_create_minor(snapname);
 		kmem_strfree(snapname);
-
-		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, drc->drc_raw);
-		}
 	}
 	return (error);
 }
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 5c53eb637794..2104bef714c2 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -27,7 +27,7 @@
  * Copyright (c) 2014, 2016 Joyent, Inc. All rights reserved.
  * Copyright 2016 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2014, Joyent, Inc. All rights reserved.
- * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  * Copyright (c) 2013 Steven Hartland. All rights reserved.
  * Copyright (c) 2014 Integros [integros.com]
@@ -4765,9 +4765,9 @@ static boolean_t zfs_ioc_recv_inject_err;
 static int
 zfs_ioc_recv_impl(char *tofs, char *tosnap, char *origin, nvlist_t *recvprops,
     nvlist_t *localprops, nvlist_t *hidden_args, boolean_t force,
-    boolean_t resumable, int input_fd, dmu_replay_record_t *begin_record,
-    int cleanup_fd, uint64_t *read_bytes, uint64_t *errflags,
-    uint64_t *action_handle, nvlist_t **errors)
+    boolean_t resumable, int input_fd,
+    dmu_replay_record_t *begin_record, uint64_t *read_bytes,
+    uint64_t *errflags, nvlist_t **errors)
 {
 	dmu_recv_cookie_t drc;
 	int error = 0;
@@ -4896,7 +4896,7 @@ zfs_ioc_recv_impl(char *tofs, char *tosnap, char *origin, nvlist_t *recvprops,
 		nvlist_free(xprops);
 	}
 
-	error = dmu_recv_stream(&drc, cleanup_fd, action_handle, &off);
+	error = dmu_recv_stream(&drc, &off);
 
 	if (error == 0) {
 		zfsvfs_t *zfsvfs = NULL;
@@ -5088,13 +5088,10 @@ zfs_ioc_recv_impl(char *tofs, char *tosnap, char *origin, nvlist_t *recvprops,
  * zc_cookie		file descriptor to recv from
  * zc_begin_record	the BEGIN record of the stream (not byteswapped)
  * zc_guid		force flag
- * zc_cleanup_fd	cleanup-on-exit file descriptor
- * zc_action_handle	handle for this guid/ds mapping (or zero on first call)
  *
  * outputs:
  * zc_cookie		number of bytes read
  * zc_obj		zprop_errflags_t
- * zc_action_handle	handle for this guid/ds mapping
  * zc_nvlist_dst{_size} error for each unapplied received property
  */
 static int
@@ -5137,8 +5134,7 @@ zfs_ioc_recv(zfs_cmd_t *zc)
 
 	error = zfs_ioc_recv_impl(tofs, tosnap, origin, recvdprops, localprops,
 	    NULL, zc->zc_guid, B_FALSE, zc->zc_cookie, &begin_record,
-	    zc->zc_cleanup_fd, &zc->zc_cookie, &zc->zc_obj,
-	    &zc->zc_action_handle, &errors);
+	    &zc->zc_cookie, &zc->zc_obj, &errors);
 	nvlist_free(recvdprops);
 	nvlist_free(localprops);
 
@@ -5171,15 +5167,14 @@ zfs_ioc_recv(zfs_cmd_t *zc)
  *     "input_fd" -> file descriptor to read stream from (int32)
  *     (optional) "force" -> force flag (value ignored)
  *     (optional) "resumable" -> resumable flag (value ignored)
- *     (optional) "cleanup_fd" -> cleanup-on-exit file descriptor
- *     (optional) "action_handle" -> handle for this guid/ds mapping
+ *     (optional) "cleanup_fd" -> unused
+ *     (optional) "action_handle" -> unused
  *     (optional) "hidden_args" -> { "wkeydata" -> value }
  * }
  *
  * outnvl: {
  *     "read_bytes" -> number of bytes read
  *     "error_flags" -> zprop_errflags_t
- *     "action_handle" -> handle for this guid/ds mapping
  *     "errors" -> error for each unapplied received property (nvlist)
  * }
  */
@@ -5212,11 +5207,9 @@ zfs_ioc_recv_new(const char *fsname, nvlist_t *innvl, nvlist_t *outnvl)
 	char tofs[ZFS_MAX_DATASET_NAME_LEN];
 	boolean_t force;
 	boolean_t resumable;
-	uint64_t action_handle = 0;
 	uint64_t read_bytes = 0;
 	uint64_t errflags = 0;
 	int input_fd = -1;
-	int cleanup_fd = -1;
 	int error;
 
 	snapname = fnvlist_lookup_string(innvl, "snapname");
@@ -5244,14 +5237,6 @@ zfs_ioc_recv_new(const char *fsname, nvlist_t *innvl, nvlist_t *outnvl)
 	force = nvlist_exists(innvl, "force");
 	resumable = nvlist_exists(innvl, "resumable");
 
-	error = nvlist_lookup_int32(innvl, "cleanup_fd", &cleanup_fd);
-	if (error && error != ENOENT)
-		return (error);
-
-	error = nvlist_lookup_uint64(innvl, "action_handle", &action_handle);
-	if (error && error != ENOENT)
-		return (error);
-
 	/* we still use "props" here for backwards compatibility */
 	error = nvlist_lookup_nvlist(innvl, "props", &recvprops);
 	if (error && error != ENOENT)
@@ -5266,12 +5251,11 @@ zfs_ioc_recv_new(const char *fsname, nvlist_t *innvl, nvlist_t *outnvl)
 		return (error);
 
 	error = zfs_ioc_recv_impl(tofs, tosnap, origin, recvprops, localprops,
-	    hidden_args, force, resumable, input_fd, begin_record, cleanup_fd,
-	    &read_bytes, &errflags, &action_handle, &errors);
+	    hidden_args, force, resumable, input_fd, begin_record,
+	    &read_bytes, &errflags, &errors);
 
 	fnvlist_add_uint64(outnvl, "read_bytes", read_bytes);
 	fnvlist_add_uint64(outnvl, "error_flags", errflags);
-	fnvlist_add_uint64(outnvl, "action_handle", action_handle);
 	fnvlist_add_nvlist(outnvl, "errors", errors);
 
 	nvlist_free(errors);
diff --git a/module/zfs/zfs_onexit.c b/module/zfs/zfs_onexit.c
index bf86446d4fad..2a1332e715ee 100644
--- a/module/zfs/zfs_onexit.c
+++ b/module/zfs/zfs_onexit.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2013, 2020 by Delphix. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -171,80 +171,3 @@ zfs_onexit_add_cb(minor_t minor, void (*func)(void *), void *data,
 
 	return (0);
 }
-
-static zfs_onexit_action_node_t *
-zfs_onexit_find_cb(zfs_onexit_t *zo, uint64_t action_handle)
-{
-	zfs_onexit_action_node_t *match;
-	zfs_onexit_action_node_t *ap;
-	list_t *l;
-
-	ASSERT(MUTEX_HELD(&zo->zo_lock));
-
-	match = (zfs_onexit_action_node_t *)(uintptr_t)action_handle;
-	l = &zo->zo_actions;
-	for (ap = list_head(l); ap != NULL; ap = list_next(l, ap)) {
-		if (match == ap)
-			break;
-	}
-	return (ap);
-}
-
-/*
- * Delete the callback, triggering it first if 'fire' is set.
- */
-int
-zfs_onexit_del_cb(minor_t minor, uint64_t action_handle, boolean_t fire)
-{
-	zfs_onexit_t *zo;
-	zfs_onexit_action_node_t *ap;
-	int error;
-
-	error = zfs_onexit_minor_to_state(minor, &zo);
-	if (error)
-		return (error);
-
-	mutex_enter(&zo->zo_lock);
-	ap = zfs_onexit_find_cb(zo, action_handle);
-	if (ap != NULL) {
-		list_remove(&zo->zo_actions, ap);
-		mutex_exit(&zo->zo_lock);
-		if (fire)
-			ap->za_func(ap->za_data);
-		kmem_free(ap, sizeof (zfs_onexit_action_node_t));
-	} else {
-		mutex_exit(&zo->zo_lock);
-		error = SET_ERROR(ENOENT);
-	}
-
-	return (error);
-}
-
-/*
- * Return the data associated with this callback.  This allows consumers
- * of the cleanup-on-exit interfaces to stash kernel data across system
- * calls, knowing that it will be cleaned up if the calling process exits.
- */
-int
-zfs_onexit_cb_data(minor_t minor, uint64_t action_handle, void **data)
-{
-	zfs_onexit_t *zo;
-	zfs_onexit_action_node_t *ap;
-	int error;
-
-	*data = NULL;
-
-	error = zfs_onexit_minor_to_state(minor, &zo);
-	if (error)
-		return (error);
-
-	mutex_enter(&zo->zo_lock);
-	ap = zfs_onexit_find_cb(zo, action_handle);
-	if (ap != NULL)
-		*data = ap->za_data;
-	else
-		error = SET_ERROR(ENOENT);
-	mutex_exit(&zo->zo_lock);
-
-	return (error);
-}
diff --git a/tests/runfiles/common.run b/tests/runfiles/common.run
index b75be778bdc2..6f83dcd8ba43 100644
--- a/tests/runfiles/common.run
+++ b/tests/runfiles/common.run
@@ -766,22 +766,22 @@ tests = ['rootpool_002_neg', 'rootpool_003_neg', 'rootpool_007_pos']
 tags = ['functional', 'rootpool']
 
 [tests/functional/rsend]
-tests = ['rsend_001_pos', 'rsend_002_pos', 'rsend_003_pos', 'rsend_004_pos',
-    'rsend_005_pos', 'rsend_006_pos', 'rsend_007_pos', 'rsend_008_pos',
-    'rsend_009_pos', 'rsend_010_pos', 'rsend_011_pos', 'rsend_012_pos',
-    'rsend_013_pos', 'rsend_014_pos', 'rsend_016_neg',
-    'rsend_019_pos', 'rsend_020_pos',
+tests = ['recv_dedup', 'recv_dedup_encrypted_zvol', 'rsend_001_pos',
+    'rsend_002_pos', 'rsend_003_pos', 'rsend_004_pos', 'rsend_005_pos',
+    'rsend_006_pos', 'rsend_007_pos', 'rsend_008_pos', 'rsend_009_pos',
+    'rsend_010_pos', 'rsend_011_pos', 'rsend_012_pos', 'rsend_013_pos',
+    'rsend_014_pos', 'rsend_016_neg', 'rsend_019_pos', 'rsend_020_pos',
     'rsend_021_pos', 'rsend_022_pos', 'rsend_024_pos',
     'send-c_verify_ratio', 'send-c_verify_contents', 'send-c_props',
     'send-c_incremental', 'send-c_volume', 'send-c_zstreamdump',
     'send-c_lz4_disabled', 'send-c_recv_lz4_disabled',
-    'send-c_mixed_compression', 'send-c_stream_size_estimate', 'send-cD',
+    'send-c_mixed_compression', 'send-c_stream_size_estimate',
     'send-c_embedded_blocks', 'send-c_resume', 'send-cpL_varied_recsize',
     'send-c_recv_dedup', 'send_encrypted_hierarchy',
     'send_encrypted_props', 'send_encrypted_truncated_files',
     'send_freeobjects', 'send_realloc_files',
     'send_realloc_encrypted_files', 'send_spill_block', 'send_holds',
-    'send_hole_birth', 'send_mixed_raw', 'send-wDR_encrypted_zvol',
+    'send_hole_birth', 'send_mixed_raw', 'send-wR_encrypted_zvol',
     'send_partial_dataset']
 tags = ['functional', 'rsend']
 
diff --git a/tests/zfs-tests/tests/functional/rsend/Makefile.am b/tests/zfs-tests/tests/functional/rsend/Makefile.am
index 8e16f8847669..7728a6481da2 100644
--- a/tests/zfs-tests/tests/functional/rsend/Makefile.am
+++ b/tests/zfs-tests/tests/functional/rsend/Makefile.am
@@ -2,6 +2,8 @@ pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/rsend
 dist_pkgdata_SCRIPTS = \
 	setup.ksh \
 	cleanup.ksh \
+	recv_dedup.ksh \
+	recv_dedup_encrypted_zvol.ksh \
 	rsend_001_pos.ksh \
 	rsend_002_pos.ksh \
 	rsend_003_pos.ksh \
@@ -25,7 +27,6 @@ dist_pkgdata_SCRIPTS = \
 	send_encrypted_hierarchy.ksh \
 	send_encrypted_props.ksh \
 	send_encrypted_truncated_files.ksh \
-	send-cD.ksh \
 	send-c_embedded_blocks.ksh \
 	send-c_incremental.ksh \
 	send-c_lz4_disabled.ksh \
@@ -49,8 +50,12 @@ dist_pkgdata_SCRIPTS = \
 	send_holds.ksh \
 	send_hole_birth.ksh \
 	send_mixed_raw.ksh \
-	send-wDR_encrypted_zvol.ksh
+	send-wR_encrypted_zvol.ksh
 
 dist_pkgdata_DATA = \
+	dedup.zsend.bz2 \
+	dedup_encrypted_zvol.bz2 \
+	dedup_encrypted_zvol.zsend.bz2 \
+	fs.tar.gz \
 	rsend.cfg \
 	rsend.kshlib
diff --git a/tests/zfs-tests/tests/functional/rsend/dedup.zsend.bz2 b/tests/zfs-tests/tests/functional/rsend/dedup.zsend.bz2
new file mode 100644
index 000000000000..585e14852662
Binary files /dev/null and b/tests/zfs-tests/tests/functional/rsend/dedup.zsend.bz2 differ
diff --git a/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.bz2 b/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.bz2
new file mode 100644
index 000000000000..73a5742fc302
Binary files /dev/null and b/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.bz2 differ
diff --git a/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.zsend.bz2 b/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.zsend.bz2
new file mode 100644
index 000000000000..04a6cb53f040
Binary files /dev/null and b/tests/zfs-tests/tests/functional/rsend/dedup_encrypted_zvol.zsend.bz2 differ
diff --git a/tests/zfs-tests/tests/functional/rsend/fs.tar.gz b/tests/zfs-tests/tests/functional/rsend/fs.tar.gz
new file mode 100644
index 000000000000..cb6861c155b7
Binary files /dev/null and b/tests/zfs-tests/tests/functional/rsend/fs.tar.gz differ
diff --git a/tests/zfs-tests/tests/functional/rsend/recv_dedup.ksh b/tests/zfs-tests/tests/functional/rsend/recv_dedup.ksh
new file mode 100755
index 000000000000..e6e282a1c6f8
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/rsend/recv_dedup.ksh
@@ -0,0 +1,53 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2020 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/rsend/rsend.kshlib
+
+#
+# DESCRIPTION:
+# Verifies that we can receive a dedup send stream by processing it with
+# "zstream redup".
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	destroy_dataset $TESTPOOL/recv "-r"
+	rm -r /$TESTPOOL/tar
+	rm $sendfile
+}
+log_onexit cleanup
+
+log_assert "Verify zfs can receive dedup send streams with 'zstream redup'"
+
+typeset sendfile_compressed=$STF_SUITE/tests/functional/rsend/dedup.zsend.bz2
+typeset sendfile=/$TESTPOOL/dedup.zsend
+typeset tarfile=$STF_SUITE/tests/functional/rsend/fs.tar.gz
+
+log_must eval "bzcat <$sendfile_compressed >$sendfile"
+log_must zfs create $TESTPOOL/recv
+log_must eval "zstream redup $sendfile | zfs recv -d $TESTPOOL/recv"
+
+log_must mkdir /$TESTPOOL/tar
+log_must tar --directory /$TESTPOOL/tar -xzf $tarfile
+log_must diff -r /$TESTPOOL/tar /$TESTPOOL/recv
+
+log_pass "zfs can receive dedup send streams with 'zstream redup'"
diff --git a/tests/zfs-tests/tests/functional/rsend/recv_dedup_encrypted_zvol.ksh b/tests/zfs-tests/tests/functional/rsend/recv_dedup_encrypted_zvol.ksh
new file mode 100755
index 000000000000..569fcd893e7d
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/rsend/recv_dedup_encrypted_zvol.ksh
@@ -0,0 +1,60 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2020 by Delphix. All rights reserved.
+#
+
+. $STF_SUITE/tests/functional/rsend/rsend.kshlib
+
+#
+# DESCRIPTION:
+# Verifies that we can receive a dedup send stream of a zvol by processing it
+# with "zstream redup".
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	destroy_dataset $TESTPOOL/recv "-r"
+	rm $sendfile
+	rm $volfile
+	rm $keyfile
+}
+log_onexit cleanup
+
+log_assert "Verify zfs can receive raw, recursive, and deduplicated send streams"
+
+typeset keyfile=/$TESTPOOL/pkey
+typeset recvdev=$ZVOL_DEVDIR/$TESTPOOL/recv
+typeset sendfile_compressed=$STF_SUITE/tests/functional/rsend/dedup_encrypted_zvol.zsend.bz2
+typeset sendfile=/$TESTPOOL/dedup_encrypted_zvol.zsend
+typeset volfile_compressed=$STF_SUITE/tests/functional/rsend/dedup_encrypted_zvol.bz2
+typeset volfile=/$TESTPOOL/dedup_encrypted_zvol
+
+log_must eval "echo 'password' > $keyfile"
+
+log_must eval "bzcat <$sendfile_compressed >$sendfile"
+log_must eval "zstream redup $sendfile | zfs recv $TESTPOOL/recv"
+
+log_must zfs load-key $TESTPOOL/recv
+block_device_wait
+
+log_must eval "bzcat <$volfile_compressed >$volfile"
+log_must diff $volfile $recvdev
+
+log_pass "zfs can receive raw, recursive, and deduplicated send streams"
diff --git a/tests/zfs-tests/tests/functional/rsend/send-cD.ksh b/tests/zfs-tests/tests/functional/rsend/send-cD.ksh
deleted file mode 100755
index fcbec2d9e9b2..000000000000
--- a/tests/zfs-tests/tests/functional/rsend/send-cD.ksh
+++ /dev/null
@@ -1,89 +0,0 @@
-#!/bin/ksh -p
-
-#
-# This file and its contents are supplied under the terms of the
-# Common Development and Distribution License ("CDDL"), version 1.0.
-# You may only use this file in accordance with the terms of version
-# 1.0 of the CDDL.
-#
-# A full copy of the text of the CDDL should have accompanied this
-# source.  A copy of the CDDL is also available via the Internet at
-# http://www.illumos.org/license/CDDL.
-#
-
-#
-# Copyright (c) 2015, 2018 by Delphix. All rights reserved.
-#
-
-. $STF_SUITE/tests/functional/rsend/rsend.kshlib
-
-#
-# Description:
-# Verify that the -c and -D flags do not interfere with each other.
-#
-# Strategy:
-# 1. Write unique data to a filesystem and create a compressed, deduplicated
-#    full stream.
-# 2. Verify that the stream and send dataset show the same size
-# 3. Make several copies of the original data, and create both full and
-#    incremental compressed, deduplicated send streams
-# 4. Verify the full stream is no bigger than the stream from step 1
-# 5. Verify the streams can be received correctly.
-#
-
-verify_runnable "both"
-
-log_assert "Verify that the -c and -D flags do not interfere with each other"
-log_onexit cleanup_pool $POOL2
-
-typeset sendfs=$POOL2/sendfs
-typeset recvfs=$POOL2/recvfs
-typeset stream0=$BACKDIR/stream.0
-typeset stream1=$BACKDIR/stream.1
-typeset inc=$BACKDIR/stream.inc
-
-log_must zfs create -o compress=lz4 $sendfs
-log_must zfs create -o compress=lz4 $recvfs
-typeset dir=$(get_prop mountpoint $sendfs)
-# Don't use write_compressible: we want compressible but undeduplicable data.
-log_must eval "dd if=/dev/urandom bs=1024k count=4 | base64 >$dir/file"
-log_must zfs snapshot $sendfs@snap0
-log_must eval "zfs send -D -c $sendfs@snap0 >$stream0"
-
-# The stream size should match at this point because the data is all unique
-verify_stream_size $stream0 $sendfs
-
-for i in {0..3}; do
-	log_must cp $dir/file $dir/file.$i
-done
-log_must zfs snapshot $sendfs@snap1
-
-# The stream sizes should match, since the second stream contains no new blocks
-log_must eval "zfs send -D -c $sendfs@snap1 >$stream1"
-typeset size0=$(stat_size $stream0)
-typeset size1=$(stat_size $stream1)
-within_percent $size0 $size1 90 || log_fail "$size0 and $size1"
-
-# make sure the receive works correctly.
-log_must eval "zfs send -D -c -i snap0 $sendfs@snap1 >$inc"
-log_must eval "zfs recv -d $recvfs <$stream0"
-log_must eval "zfs recv -d $recvfs <$inc"
-cmp_ds_cont $sendfs $recvfs
-
-# check receive with redup.
-log_must zfs destroy -r $recvfs
-log_must zfs create -o compress=lz4 $recvfs
-log_must eval "zstream redup $stream0 | zfs recv -d $recvfs"
-log_must eval "zstream redup $inc | zfs recv -d $recvfs"
-cmp_ds_cont $sendfs $recvfs
-
-# The size of the incremental should be the same as the initial send.
-typeset size2=$(stat_size $inc)
-within_percent $size0 $size2 90 || log_fail "$size0 and $size1"
-
-# The redup'ed size should be 4x
-typeset size3=$(zstream redup $inc | wc -c)
-let size4=size0*4
-within_percent $size4 $size3 90 || log_fail "$size4 and $size3"
-
-log_pass "The -c and -D flags do not interfere with each other"
diff --git a/tests/zfs-tests/tests/functional/rsend/send-wDR_encrypted_zvol.ksh b/tests/zfs-tests/tests/functional/rsend/send-wR_encrypted_zvol.ksh
similarity index 84%
rename from tests/zfs-tests/tests/functional/rsend/send-wDR_encrypted_zvol.ksh
rename to tests/zfs-tests/tests/functional/rsend/send-wR_encrypted_zvol.ksh
index f9cfeee214f2..b95fc3da30c3 100755
--- a/tests/zfs-tests/tests/functional/rsend/send-wDR_encrypted_zvol.ksh
+++ b/tests/zfs-tests/tests/functional/rsend/send-wR_encrypted_zvol.ksh
@@ -16,20 +16,21 @@
 
 #
 # Copyright (c) 2018 by Datto Inc. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/tests/functional/rsend/rsend.kshlib
 
 #
 # DESCRIPTION:
-# Verify that zvols with dedup=on and encryption=on can be sent and received
-# with a deduplicated raw send stream.
+# Verify that zvols with encryption=on can be sent and received with a raw
+# send stream.
 #
 # STRATEGY:
-# 1. Create a zvol with dedup and encryption on and put a filesystem on it
+# 1. Create a zvol with encryption on and put a filesystem on it
 # 2. Copy a file into the zvol a few times and take a snapshot
 # 3. Repeat step 2 a few times to create more snapshots
-# 4. Send all snapshots in a recursive, raw, deduplicated send stream
+# 4. Send all snapshots in a recursive, raw send stream
 # 5. Mount the received zvol and verify that all of the data there is correct
 #
 
@@ -48,7 +49,7 @@ function cleanup
 }
 log_onexit cleanup
 
-log_assert "Verify zfs can receive raw, recursive, and deduplicated send streams"
+log_assert "Verify zfs can receive raw, recursive send streams"
 
 typeset keyfile=/$TESTPOOL/pkey
 typeset snap_count=5
@@ -93,7 +94,7 @@ for ((i = 1; i <= $snap_count; i++)); do
 	log_must mount $remount_rw $zdev $mntpnt
 done
 
-log_must eval "zfs send -wDR $TESTPOOL/$TESTVOL@snap$snap_count > $sendfile"
+log_must eval "zfs send -wR $TESTPOOL/$TESTVOL@snap$snap_count > $sendfile"
 log_must eval "zfs recv $TESTPOOL/recv < $sendfile"
 log_must zfs load-key $TESTPOOL/recv
 block_device_wait
@@ -104,4 +105,4 @@ md5_1=$(cat $mntpnt/* | md5digest)
 md5_2=$(cat $recvmnt/* | md5digest)
 [[ "$md5_1" == "$md5_2" ]] || log_fail "md5 mismatch: $md5_1 != $md5_2"
 
-log_pass "zfs can receive raw, recursive, and deduplicated send streams"
+log_pass "zfs can receive raw, recursive send streams"
diff --git a/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh b/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
index 8a097159616d..d5eb9a0edc11 100755
--- a/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
+++ b/tests/zfs-tests/tests/functional/rsend/send_partial_dataset.ksh
@@ -13,6 +13,7 @@
 
 #
 # Copyright (c) 2019 Datto Inc.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -98,7 +99,6 @@ set -A badargs \
 	"-R $POOL/recvfs" \
 	"-p $POOL/recvfs" \
 	"-I $POOL/recvfs" \
-	"-D $POOL/recvfs" \
 	"-h $POOL/recvfs"
 
 while (( i < ${#badargs[*]} ))