Relax (ref)reservation constraints on ZVOLs

This change allow (ref)reservation 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

@@ -1451,25 +1451,11 @@ zfs_valid_proplist(libzfs_handle_t *hdl, zfs_type_t type, nvlist_t *nvl,
 		 * checks to enforce.
 		 */
 		if (type == ZFS_TYPE_VOLUME && zhp != NULL) {
-			uint64_t volsize = zfs_prop_get_int(zhp,
-			    ZFS_PROP_VOLSIZE);
 			uint64_t blocksize = zfs_prop_get_int(zhp,
 			    ZFS_PROP_VOLBLOCKSIZE);
 			char buf[64];
 
 			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 "
-					    "volume size"), propname);
-					(void) zfs_error(hdl, EZFS_BADPROP,
-					    errbuf);
-					goto error;
-				}
-				break;
-
 			case ZFS_PROP_VOLSIZE:
 				if (intval % blocksize != 0) {
 					zfs_nicebytes(blocksize, buf,

tests/zfs-tests/tests/functional/refreserv/refreserv_005_pos.ksh

@@ -33,13 +33,12 @@
 
 #
 # DESCRIPTION:
-#	Volume refreservation is limited by volsize
+#	Volume (ref)reservation is not limited by volsize
 #
 # STRATEGY:
 #	1. Create volume on filesystem
 #	2. Setting quota for parent filesystem
-#	3. Verify volume refreservation is only limited by volsize
-#	4. Verify volume refreservation can be changed when volsize changed
+#	3. Verify volume (ref)reservation is not limited by volsize
 #
 
 verify_runnable "global"
@@ -51,21 +50,24 @@ function cleanup
 	log_must zfs set mountpoint=$TESTDIR $TESTPOOL/$TESTFS
 }
 
-log_assert "Volume refreservation is limited by volsize"
+log_assert "Volume (ref)reservation is not limited by volsize"
 log_onexit cleanup
 
-fs=$TESTPOOL/$TESTFS; vol=$fs/vol
+fs=$TESTPOOL/$TESTFS
+vol=$fs/vol
 log_must zfs create -V 10M $vol
+refreserv=`get_prop refreservation $vol`
+fudge=1
 
 # Verify the parent filesystem does not affect volume
 log_must zfs set quota=25M $fs
+log_must zfs set reservation=10M $vol
 log_must zfs set refreservation=10M $vol
-avail=$(get_prop mountpoint $vol)
-log_mustnot zfs set refreservation=$avail $vol
 
-# Verify it is affected by volsize
-log_must zfs set volsize=15M $vol
-log_must zfs set refreservation=15M $vol
-log_mustnot zfs set refreservation=16M $vol
+# Verify it is not affected by volsize
+log_must zfs set reservation=$(($refreserv + $fudge)) $vol
+log_must zfs set reservation=$(($refreserv - $fudge)) $vol
+log_must zfs set refreservation=$(($refreserv + $fudge)) $vol
+log_must zfs set refreservation=$(($refreserv - $fudge)) $vol
 
-log_pass "Volume refreservation is limited by volsize"
+log_pass "Volume (ref)reservation is not limited by volsize"