Relax refreservation constraints on ZVOLs

This change allow refreservation to be set larger than the current
ZVOL size: this is safe as we normally set refreservation > volsize
at ZVOL creation time when we account for metadata.

Signed-off-by: loli10K <ezomori.nozomu@gmail.com>

lib/libzfs/libzfs_dataset.c

@@ -1459,7 +1459,6 @@ zfs_valid_proplist(libzfs_handle_t *hdl, zfs_type_t type, nvlist_t *nvl,
 
 			switch (prop) {
 			case ZFS_PROP_RESERVATION:
-			case ZFS_PROP_REFRESERVATION:
 				if (intval > volsize) {
 					zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
 					    "'%s' is greater than current "

tests/runfiles/linux.run

@@ -151,7 +151,8 @@ tests = ['zfs_rename_001_pos', 'zfs_rename_002_pos', 'zfs_rename_003_pos',
     'zfs_rename_to_encrypted']
 
 [tests/functional/cli_root/zfs_reservation]
-tests = ['zfs_reservation_001_pos', 'zfs_reservation_002_pos']
+tests = ['zfs_reservation_001_pos', 'zfs_reservation_002_pos',
+    'zfs_reservation_bigger']
 
 [tests/functional/cli_root/zfs_rollback]
 tests = ['zfs_rollback_001_pos', 'zfs_rollback_002_pos',

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

@@ -3,4 +3,5 @@ dist_pkgdata_SCRIPTS = \
 	setup.ksh \
 	cleanup.ksh \
 	zfs_reservation_001_pos.ksh \
-	zfs_reservation_002_pos.ksh
+	zfs_reservation_002_pos.ksh \
+	zfs_reservation_bigger.ksh

tests/zfs-tests/tests/functional/cli_root/zfs_reservation/zfs_reservation_bigger.ksh

@@ -0,0 +1,73 @@
+#!/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
+
+#
+# DESCRIPTION:
+#
+# Verify refreservation can be set bigger than then current ZVOL size
+#
+# STRATEGY:
+# 1. Create a ZVOL with initial refreservation
+# 2. Remove the refreservation
+# 3. Verify we can set the old refreservation value again on the ZVOL
+#
+
+verify_runnable "both"
+
+function cleanup
+{
+	datasetexists $ZVOL && log_must_busy zfs destroy -f $ZVOL
+}
+
+log_onexit cleanup
+
+log_assert "Verify refreservation can be set bigger than then current ZVOL size"
+
+ZVOL="$TESTPOOL/$TESTVOL"
+volsize="$((1024 * 1024 * 64))" # 64M
+
+# 1. Create a ZVOL with initial refreservation
+log_must zfs create -V $volsize $ZVOL
+refreserv=`get_prop refreservation $ZVOL`
+if [[ $refreserv -le $volsize ]]; then
+	log_fail "Unexpected refreservation on $ZVOL ($refreserv <= $volsize)"
+fi
+
+# 2. Remove the refreservation
+log_must zfs set refreservation=none $ZVOL
+if [[ `get_prop refreservation $ZVOL` != 0 ]]; then
+	log_fail "Could not correctly remove refreservation on $ZVOL"
+fi
+
+# 3. Verify we can set the same refreservation value again on the ZVOL
+log_must zfs set refreservation=$refreserv $ZVOL
+if [[ `get_prop refreservation $ZVOL` != $refreserv ]]; then
+	log_fail "Could not correctly set refreservation to old value on $ZVOL"
+fi
+
+log_pass "Successfully set refreservation on ZVOL"