Fix bug in zfs_prop_set_special() that broke setting compression

We only want to handle feature activation in the special callback,
the actual property setting can still happen the normal way.

Signed-off-by: Allan Jude <allanjude@freebsd.org>

Author: allanjude

module/zfs/zfs_ioctl.c

@@ -2484,6 +2484,12 @@ zfs_prop_set_special(const char *dsname, zprop_source_t source,
 		break;
 	case ZFS_PROP_COMPRESSION:
 		err = dsl_dataset_set_compression(dsname, source, intval);
+		/*
+		 * Set err to -1 to force the zfs_set_prop_nvlist code down the
+		 * default path to set the value in the nvlist.
+		 */
+		if (err == 0)
+			err = -1;
 		break;
 	case ZFS_PROP_VOLSIZE:
 		err = zvol_set_volsize(dsname, intval);