maple_tree: fix get wrong data_end in mtree_lookup_walk()

if (likely(offset > end))
	max = pivots[offset];

The above code should be changed to if (likely(offset < end)), which is
correct.  This affects the correctness of ma_data_end().  Now it seems
that the final result will not be wrong, but it is best to change it. 
This patch does not change the code as above, because it simplifies the
code by the way.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 54a611b ("Maple Tree: add new data structure")
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Peng Zhang

lib/maple_tree.c

@@ -3941,18 +3941,13 @@ static inline void *mtree_lookup_walk(struct ma_state *mas)
 		end = ma_data_end(node, type, pivots, max);
 		if (unlikely(ma_dead_node(node)))
 			goto dead_node;
-
-		if (pivots[offset] >= mas->index)
-			goto next;
-
 		do {
-			offset++;
-		} while ((offset < end) && (pivots[offset] < mas->index));
-
-		if (likely(offset > end))
-			max = pivots[offset];
+			if (pivots[offset] >= mas->index) {
+				max = pivots[offset];
+				break;
+			}
+		} while (++offset < end);
 
-next:
 		slots = ma_slots(node, type);
 		next = mt_slot(mas->tree, slots, offset);
 		if (unlikely(ma_dead_node(node)))