Remove deduplicated send/receive code

Deduplicated send streams (i.e. `zfs send -D` and `zfs receive` of such
streams) are deprecated.  Deduplicated send streams can be received by
first converting them to non-deduplicated with the `zstream redup`
command.

This commit removes the code for sending and receiving deduplicated send
streams.  `zfs send -D` will now print a warning, ignore the `-D` flag,
and generate a regular (non-deduplicated) send stream.  `zfs receive` of
a deduplicated send stream will print an error message and fail.

The resulting code simplification (especially in the kernel's support
for receiving dedup streams) should help enable future performance
enhancements.

Several new tests are added which leverage `zstream redup`.

Reviewed-by: Paul Dagnelie <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Matthew Ahrens <[email protected]>
Issue #7887
Issue #10117
Issue #10156
Closes #10212 

4 files changed, 19 insertions, 377 deletions

diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 6eb935720..a21ac8d74 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 9c82cecc6..817c85b93 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 <[email protected]>. 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;
@@ -1213,38 +1204,6 @@ dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
 }
 
 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)
 {
 	int done = 0;
@@ -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 @@ out:
 
 	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 5c53eb637..2104bef71 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 @@ out:
  * 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 bf86446d4..2a1332e71 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);
-}