vdev_label_os: copy Linux implementation for userspace

The no-op is fine for both.

Reviewed by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-by: https://despairlabs.com/sponsor/
Closes openzfs#16492

lib/libzpool/Makefile.am

@@ -15,7 +15,8 @@ dist_libzpool_la_SOURCES = \
 	%D%/arc_os.c \
 	%D%/kernel.c \
 	%D%/taskq.c \
-	%D%/util.c
+	%D%/util.c \
+	%D%/vdev_label_os.c
 
 nodist_libzpool_la_SOURCES = \
 	module/lua/lapi.c \

lib/libzpool/vdev_label_os.c

@@ -0,0 +1,45 @@
+/*
+ * 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 https://opensource.org/licenses/CDDL-1.0.
+ * 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 (c) 2023 by iXsystems, Inc.
+ */
+
+#include <sys/zfs_context.h>
+#include <sys/spa.h>
+#include <sys/spa_impl.h>
+#include <sys/vdev.h>
+#include <sys/vdev_impl.h>
+
+/*
+ * Check if the reserved boot area is in-use.
+ *
+ * This function always returns 0, as there are no known external uses
+ * of the reserved area on Linux.
+ */
+int
+vdev_check_boot_reserve(spa_t *spa, vdev_t *childvd)
+{
+	(void) spa;
+	(void) childvd;
+
+	return (0);
+}