maple_tree: avoid ascending when mas->min is also the parent's minimum

When the child node is the first child of its parent node, mas->min does
not need to be updated. This can reduce the number of ascending times
in some cases.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: Dan Carpenter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Peng Zhang

lib/maple_tree.c

@@ -1088,14 +1088,16 @@ static int mas_ascend(struct ma_state *mas)
 		return 0;
 	}
 
-	if (!mas->min)
+	min = 0;
+	max = ULONG_MAX;
+	if (!mas->offset) {
+		min = mas->min;
 		set_min = true;
+	}
 
 	if (mas->max == ULONG_MAX)
 		set_max = true;
 
-	min = 0;
-	max = ULONG_MAX;
 	do {
 		p_enode = a_enode;
 		a_type = mas_parent_type(mas, p_enode);