mm: improve code consistency with zonelist_* helper functions

Replace direct access to zoneref->zone, zoneref->zone_idx, or
zone_to_nid(zoneref->zone) with the corresponding zonelist_* helper
functions for consistency.

No functional change.

Link: https://lkml.kernel.org/r/[e-mail]
Co-developed-by: Shivank Garg <[e-mail]>
Signed-off-by: Shivank Garg <[e-mail]>
Signed-off-by: Wei Yang <[e-mail]>
Acked-by: David Hildenbrand <[e-mail]>
Cc: Mike Rapoport (IBM) <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/mmzone.h

···
 			zone = zonelist_zone(z))
 
 #define for_next_zone_zonelist_nodemask(zone, z, highidx, nodemask) \
-	for (zone = z->zone;	\
+	for (zone = zonelist_zone(z);	\
 		zone;							\
 		z = next_zones_zonelist(++z, highidx, nodemask),	\
 			zone = zonelist_zone(z))
···
 	nid = first_node(*nodes);
 	zonelist = &NODE_DATA(nid)->node_zonelists[ZONELIST_FALLBACK];
 	z = first_zones_zonelist(zonelist, ZONE_NORMAL,	nodes);
-	return (!z->zone) ? true : false;
+	return (!zonelist_zone(z)) ? true : false;
 }
 
 

include/trace/events/oom.h

···
 	),
 
 	TP_fast_assign(
-		__entry->node = zone_to_nid(zoneref->zone);
-		__entry->zone_idx = zoneref->zone_idx;
+		__entry->node = zonelist_node_idx(zoneref);
+		__entry->zone_idx = zonelist_zone_idx(zoneref);
 		__entry->order = order;
 		__entry->reclaimable = reclaimable;
 		__entry->available = available;

mm/mempolicy.c

···
 		zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
 		z = first_zones_zonelist(zonelist, highest_zoneidx,
 							&policy->nodes);
-		return z->zone ? zone_to_nid(z->zone) : node;
+		return zonelist_zone(z) ? zonelist_node_idx(z) : node;
 	}
 	case MPOL_LOCAL:
 		return node;
···
 				node_zonelist(thisnid, GFP_HIGHUSER),
 				gfp_zone(GFP_HIGHUSER),
 				&pol->nodes);
-		polnid = zone_to_nid(z->zone);
+		polnid = zonelist_node_idx(z);
 		break;
 
 	default:

mm/mmzone.c

···
 			z++;
 	else
 		while (zonelist_zone_idx(z) > highest_zoneidx ||
-				(z->zone && !zref_in_nodemask(z, nodes)))
+				(zonelist_zone(z) && !zref_in_nodemask(z, nodes)))
 			z++;
 
 	return z;

mm/page_alloc.c

···
 		}
 
 		if (no_fallback && nr_online_nodes > 1 &&
-		    zone != ac->preferred_zoneref->zone) {
+		    zone != zonelist_zone(ac->preferred_zoneref)) {
 			int local_nid;
 
 			/*
···
 			 * fragmenting fallbacks. Locality is more important
 			 * than fragmentation avoidance.
 			 */
-			local_nid = zone_to_nid(ac->preferred_zoneref->zone);
+			local_nid = zonelist_node_idx(ac->preferred_zoneref);
 			if (zone_to_nid(zone) != local_nid) {
 				alloc_flags &= ~ALLOC_NOFRAGMENT;
 				goto retry;
···
 				goto try_this_zone;
 
 			if (!node_reclaim_enabled() ||
-			    !zone_allows_reclaim(ac->preferred_zoneref->zone, zone))
+			    !zone_allows_reclaim(zonelist_zone(ac->preferred_zoneref), zone))
 				continue;
 
 			ret = node_reclaim(zone->zone_pgdat, gfp_mask, order);
···
 		}
 
 try_this_zone:
-		page = rmqueue(ac->preferred_zoneref->zone, zone, order,
+		page = rmqueue(zonelist_zone(ac->preferred_zoneref), zone, order,
 				gfp_mask, alloc_flags, ac->migratetype);
 		if (page) {
 			prep_new_page(page, order, gfp_mask, alloc_flags);
···
 	 */
 	ac->preferred_zoneref = first_zones_zonelist(ac->zonelist,
 					ac->highest_zoneidx, ac->nodemask);
-	if (!ac->preferred_zoneref->zone)
+	if (!zonelist_zone(ac->preferred_zoneref))
 		goto nopage;
 
 	/*
···
 		struct zoneref *z = first_zones_zonelist(ac->zonelist,
 					ac->highest_zoneidx,
 					&cpuset_current_mems_allowed);
-		if (!z->zone)
+		if (!zonelist_zone(z))
 			goto nopage;
 	}
 
···
 			continue;
 		}
 
-		if (nr_online_nodes > 1 && zone != ac.preferred_zoneref->zone &&
-		    zone_to_nid(zone) != zone_to_nid(ac.preferred_zoneref->zone)) {
+		if (nr_online_nodes > 1 && zone != zonelist_zone(ac.preferred_zoneref) &&
+		    zone_to_nid(zone) != zonelist_node_idx(ac.preferred_zoneref)) {
 			goto failed;
 		}
 
···
 	pcp_trylock_finish(UP_flags);
 
 	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
-	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
+	zone_statistics(zonelist_zone(ac.preferred_zoneref), zone, nr_account);
 
 out:
 	return nr_populated;
···
 	 * Forbid the first pass from falling back to types that fragment
 	 * memory until all local zones are considered.
 	 */
-	alloc_flags |= alloc_flags_nofragment(ac.preferred_zoneref->zone, gfp);
+	alloc_flags |= alloc_flags_nofragment(zonelist_zone(ac.preferred_zoneref), gfp);
 
 	/* First allocation attempt */
 	page = get_page_from_freelist(alloc_gfp, order, alloc_flags, &ac);
···
 	z = first_zones_zonelist(node_zonelist(node, GFP_KERNEL),
 				   gfp_zone(GFP_KERNEL),
 				   NULL);
-	return zone_to_nid(z->zone);
+	return zonelist_node_idx(z);
 }
 #endif