mm/page-writeback.c: use min3/max3 macros to avoid shadow warnings

Nested calls to min/max functions result in shadow warnings in W=2 builds.
 Avoid the warning by using the min3 and max3 macros to get the min/max of
3 values instead of nested calls.
Signed-off-by: NMark Rustad <mark.d.rustad@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/page-writeback.c

@@ -1075,13 +1075,13 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
 	}
 
 	if (dirty < setpoint) {
-		x = min(bdi->balanced_dirty_ratelimit,
-			 min(balanced_dirty_ratelimit, task_ratelimit));
+		x = min3(bdi->balanced_dirty_ratelimit,
+			 balanced_dirty_ratelimit, task_ratelimit);
 		if (dirty_ratelimit < x)
 			step = x - dirty_ratelimit;
 	} else {
-		x = max(bdi->balanced_dirty_ratelimit,
-			 max(balanced_dirty_ratelimit, task_ratelimit));
+		x = max3(bdi->balanced_dirty_ratelimit,
+			 balanced_dirty_ratelimit, task_ratelimit);
 		if (dirty_ratelimit > x)
 			step = dirty_ratelimit - x;
 	}