Keep information in the metaslab class to know in which rotor vector …

…to place vdevs.

Todo: The guid list should not have a fixed length but be dynamic.

include/sys/metaslab_impl.h

@@ -116,6 +116,14 @@ struct metaslab_class {
 	/* total deflated space */
 	uint64_t		mc_dspacev[METASLAB_CLASS_ROTORS];
 	uint64_t		mc_histogram[RANGE_TREE_HISTOGRAM_SIZE];
+
+	/* Maximum allocation size in each rotor vector category. */
+	uint64_t		mc_rotvec_threshold[METASLAB_CLASS_ROTORS];
+	/* List of vdev guids to place in each rotor vector category. */
+	/* Should be a dynamic list. */
+	uint64_t		mc_rotvec_vdev_guids[METASLAB_CLASS_ROTORS][5];
+	/* vdev types to place in rotor vector category, if no guid match. */
+	int			mc_rotvec_categories[METASLAB_CLASS_ROTORS];
 };
 
 /*