Allow sys/vdev_disk.h to have OS fields

Based on the same style as zfs_znode_os.h.
Create an os/$platform/sys/vdev_disk_os.h for each platform, move
Linux specific fields into it. Currently it leaves FreeBSD's empty.

macOS header file will come in a future PR.

Signed-off-by: Jorgen Lundman <lundman@lundman.net>

include/os/freebsd/zfs/sys/Makefile.am

@@ -2,6 +2,7 @@ KERNEL_H = \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/freebsd_crypto.h \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/sha2.h \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/vdev_os.h \
+	$(top_srcdir)/include/os/freebsd/zfs/sys/vdev_disk_os.h \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/zfs_context_os.h \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/zfs_ctldir.h \
 	$(top_srcdir)/include/os/freebsd/zfs/sys/zfs_dir.h \

include/os/freebsd/zfs/sys/vdev_disk_os.h

@@ -0,0 +1,28 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (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
+ */
+
+#ifndef ZFS_VDEV_DISK_OS_H
+#define	ZFS_VDEV_DISK_OS_H
+
+#define	VDEV_DISK_OS_FIELDS
+
+#endif

include/os/linux/zfs/sys/Makefile.am

@@ -16,6 +16,7 @@ KERNEL_H = \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_zil.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_zio.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/trace_zrlock.h \
+	$(top_srcdir)/include/os/linux/zfs/sys/vdev_disk_os.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/zfs_context_os.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/zfs_ctldir.h \
 	$(top_srcdir)/include/os/linux/zfs/sys/zfs_dir.h \

include/os/linux/zfs/sys/vdev_disk_os.h

@@ -0,0 +1,30 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License, Version 1.0 only
+ * (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
+ */
+
+#ifndef ZFS_VDEV_DISK_OS_H
+#define	ZFS_VDEV_DISK_OS_H
+
+#define	VDEV_DISK_OS_FIELDS						\
+	struct block_device	*vd_bdev;				\
+	krwlock_t		vd_lock;
+
+#endif

include/sys/vdev_disk.h

@@ -42,12 +42,17 @@
 
 #ifdef _KERNEL
 #include <sys/vdev.h>
+#include <sys/vdev_disk_os.h>
 
 typedef struct vdev_disk {
+	/* Common members */
 	ddi_devid_t		vd_devid;
 	char			*vd_minor;
-	struct block_device	*vd_bdev;
-	krwlock_t		vd_lock;
+	/*
+	 * Platform specific field, defined by each platform and only
+	 * accessable from platform specific code.
+	 */
+	VDEV_DISK_OS_FIELDS
 } vdev_disk_t;
 
 #endif /* _KERNEL */