Fix encryption hierarchy issues with zfs recv -d

Currently, the recv_fix_encryption_hierarchy() function accepts
'destsnap' as one of its parameters. Originally, this was intended
to be the top-level dataset of a receive (whether or not the
receive was recursive). Unfortunately, this parameter actually is
simply the input that is passed in from the command line. When
the user specifies 'zfs recv -d', this string is actually only the
name of the receiving pool since the rest of the name is derived
from the send stream. This causes the function to fail, leaving
some datasets with an invalid encryption hierarchy.

This patch resolves this problem by passing in the top_zfs variable
instead. In order to make this work, this patch also includes some
changes that ensure the value is always present when we need it.

Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #9273
Closes #9309

tests/runfiles/linux.run

@@ -212,7 +212,7 @@ tests = ['zfs_receive_001_pos', 'zfs_receive_002_pos', 'zfs_receive_003_pos',
     'zfs_receive_013_pos', 'zfs_receive_014_pos', 'zfs_receive_015_pos',
     'receive-o-x_props_override', 'zfs_receive_from_encrypted',
     'zfs_receive_to_encrypted', 'zfs_receive_raw',
-    'zfs_receive_raw_incremental', 'zfs_receive_-e']
+    'zfs_receive_raw_incremental', 'zfs_receive_-e', 'zfs_receive_raw_-d']
 tags = ['functional', 'cli_root', 'zfs_receive']
 
 [tests/functional/cli_root/zfs_rename]

tests/zfs-tests/tests/functional/cli_root/zfs_receive/Makefile.am

@@ -22,4 +22,5 @@ dist_pkgdata_SCRIPTS = \
 	zfs_receive_to_encrypted.ksh \
 	zfs_receive_raw.ksh \
 	zfs_receive_raw_incremental.ksh \
+	zfs_receive_raw_-d.ksh \
 	zfs_receive_-e.ksh

tests/zfs-tests/tests/functional/cli_root/zfs_receive/zfs_receive_raw_-d.ksh

@@ -0,0 +1,62 @@
+#!/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) 2019 Datto, Inc. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+
+#
+# DESCRIPTION:
+# zfs receive -d should create the expected encryption hierarchy.
+#
+# STRATEGY:
+# 1. Create an encrypted dataset and a inheriting child
+# 2. Snapshot the child dataset
+# 2. Create a recursive raw send file from the snapshot
+# 3. Destroy the original child filesystem
+# 4. Receive the snapshot as a child of the second dataset with '-d'
+# 5. Verify the new child can be mounted
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	datasetexists $TESTPOOL/$TESTFS1 && \
+		log_must zfs destroy -r $TESTPOOL/$TESTFS1
+	rm -f $sendfile
+}
+
+log_onexit cleanup
+
+log_assert "zfs receive -d should create the expected encryption hierarchy"
+
+typeset passphrase="password1"
+
+sendfile=$TEST_BASE_DIR/sendfile.$$
+
+log_must eval "echo $passphrase | zfs create -o encryption=on" \
+	"-o keyformat=passphrase $TESTPOOL/$TESTFS1"
+log_must zfs create $TESTPOOL/$TESTFS1/child
+log_must zfs snapshot $TESTPOOL/$TESTFS1/child@snap
+log_must eval "zfs send -Rw $TESTPOOL/$TESTFS1/child@snap > $sendfile"
+log_must zfs destroy -r $TESTPOOL/$TESTFS1/child
+log_must zfs receive -Fd $TESTPOOL < $sendfile
+log_must eval "echo $passphrase | zfs mount -l $TESTPOOL/$TESTFS1/child"
+
+log_pass "zfs receive -d creates the expected encryption hierarchy"