7938 disable LBA weighting on files and SSDs
Reviewed by: Yuri Pankov <yuripv@gmx.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>

@@ -57,10 +57,15 @@
         vnode_t *vp;
         vattr_t vattr;
         int error;
 
         /*
+         * Rotational optimizations only make sense on block devices
+         */
+        vd->vdev_nonrot = B_TRUE;
+
+        /*
          * We must have a pathname, and it must be absolute.
          */
         if (vd->vdev_path == NULL || vd->vdev_path[0] != '/') {
                 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
                 return (SET_ERROR(EINVAL));