--- a/usr/src/uts/common/fs/zfs/sys/vdev_impl.h	Sun May 20 02:46:39 2012 -0500
+++ b/usr/src/uts/common/fs/zfs/sys/vdev_impl.h	Mon May 21 12:11:39 2012 -0700
@@ -202,7 +202,7 @@
 	 * For DTrace to work in userland (libzpool) context, these fields must
 	 * remain at the end of the structure.  DTrace will use the kernel's
 	 * CTF definition for 'struct vdev', and since the size of a kmutex_t is
-	 * larger in userland, the offsets for the rest fields would be
+	 * larger in userland, the offsets for the rest of the fields would be
 	 * incorrect.
 	 */
 	kmutex_t	vdev_dtl_lock;	/* vdev_dtl_{map,resilver}	*/
@@ -257,6 +257,7 @@
 #define	VDEV_LABEL_START_SIZE	(2 * sizeof (vdev_label_t) + VDEV_BOOT_SIZE)
 #define	VDEV_LABEL_END_SIZE	(2 * sizeof (vdev_label_t))
 #define	VDEV_LABELS		4
+#define	VDEV_BEST_LABEL		VDEV_LABELS
 
 #define	VDEV_ALLOC_LOAD		0
 #define	VDEV_ALLOC_ADD		1