Fix 'zpool clear' on readonly pools

Illumos 4080 inadvertently allows 'zpool clear' on readonly pools: fix
this by reintroducing a check (POOL_CHECK_READONLY) in zfs_ioc_clear
registration code.

Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #6306

tests/runfiles/linux.run

@@ -200,7 +200,8 @@ tests = ['zpool_add_001_pos', 'zpool_add_002_pos', 'zpool_add_003_pos',
 tests = ['zpool_attach_001_neg', 'attach-o_ashift']
 
 [tests/functional/cli_root/zpool_clear]
-tests = ['zpool_clear_001_pos', 'zpool_clear_002_neg', 'zpool_clear_003_neg']
+tests = ['zpool_clear_001_pos', 'zpool_clear_002_neg', 'zpool_clear_003_neg',
+    'zpool_clear_readonly']
 
 [tests/functional/cli_root/zpool_create]
 tests = ['zpool_create_001_pos', 'zpool_create_002_pos',

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

@@ -5,4 +5,5 @@ dist_pkgdata_SCRIPTS = \
 	cleanup.ksh \
 	zpool_clear_001_pos.ksh \
 	zpool_clear_002_neg.ksh \
-	zpool_clear_003_neg.ksh
+	zpool_clear_003_neg.ksh \
+	zpool_clear_readonly.ksh

tests/zfs-tests/tests/functional/cli_root/zpool_clear/zpool_clear_readonly.ksh

@@ -0,0 +1,71 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or http://www.opensolaris.org/os/licensing.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright 2017, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/cli_root/zpool_clear/zpool_clear.cfg
+
+#
+# DESCRIPTION:
+# Verify 'zpool clear' cannot be used on readonly pools.
+#
+# STRATEGY:
+# 1. Create a pool.
+# 2. Export the pool and import it readonly.
+# 3. Verify 'zpool clear' on the pool (and each device) returns an error.
+#
+
+verify_runnable "global"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL1
+	rm -f $TESTDIR/file.*
+}
+
+log_assert "Verify 'zpool clear' cannot be used on readonly pools."
+log_onexit cleanup
+
+# 1. Create a pool.
+log_must truncate -s $FILESIZE $TESTDIR/file.{1,2,3}
+log_must zpool create $TESTPOOL1 raidz $TESTDIR/file.*
+
+# 2. Export the pool and import it readonly.
+log_must zpool export $TESTPOOL1
+log_must zpool import -d $TESTDIR -o readonly=on $TESTPOOL1
+if [[ "$(get_pool_prop readonly $TESTPOOL1)" != 'on' ]]; then
+	log_fail "Pool $TESTPOOL1 was not imported readonly."
+fi
+
+# 3. Verify 'zpool clear' on the pool (and each device) returns an error.
+log_mustnot zpool clear $TESTPOOL1
+for i in {1..3}; do
+	# Device must be online
+	log_must check_state $TESTPOOL1 $TESTDIR/file.$i 'online'
+	# Device cannot be cleared if the pool was imported readonly
+	log_mustnot zpool clear $TESTPOOL1 $TESTDIR/file.$i
+done
+
+log_pass "'zpool clear' fails on readonly pools as expected."