maple_tree: use cached node end in mas_next()

When looking for the next entry, don't recalculate the node end as it is
now tracked in the maple state.

Link: https://lkml.kernel.org/r/20231101171629.3612299-6-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/maple_tree.c

@@ -4539,6 +4539,7 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
 	unsigned long min;
 	unsigned long *pivots;
 	struct maple_enode *enode;
+	struct maple_node *tmp;
 	int level = 0;
 	unsigned char node_end;
 	enum maple_type mt;
@@ -4591,6 +4592,10 @@ static inline int mas_next_node(struct ma_state *mas, struct maple_node *node,
 		pivots = ma_pivots(node, mt);
 
 	mas->max = mas_safe_pivot(mas, pivots, mas->offset, mt);
+	tmp = mte_to_node(enode);
+	mt = mte_node_type(enode);
+	pivots = ma_pivots(tmp, mt);
+	mas->end = ma_data_end(tmp, mt, pivots, mas->max);
 	if (unlikely(ma_dead_node(node)))
 		return 1;
 
@@ -4625,20 +4630,18 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty,
 	unsigned long pivot;
 	enum maple_type type;
 	struct maple_node *node;
-	unsigned char data_end;
 	unsigned long save_point = mas->last;
 	void *entry;
 
 retry:
 	node = mas_mn(mas);
 	type = mte_node_type(mas->node);
 	pivots = ma_pivots(node, type);
-	data_end = ma_data_end(node, type, pivots, mas->max);
 	if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
 		goto retry;
 
 	if (mas->max >= max) {
-		if (likely(mas->offset < data_end))
+		if (likely(mas->offset < mas->end))
 			pivot = pivots[mas->offset];
 		else
 			goto overflow;
@@ -4650,11 +4653,11 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty,
 			goto overflow;
 	}
 
-	if (likely(mas->offset < data_end)) {
+	if (likely(mas->offset < mas->end)) {
 		mas->index = pivots[mas->offset] + 1;
 again:
 		mas->offset++;
-		if (likely(mas->offset < data_end))
+		if (likely(mas->offset < mas->end))
 			mas->last = pivots[mas->offset];
 		else
 			mas->last = mas->max;
@@ -4691,7 +4694,6 @@ static void *mas_next_slot(struct ma_state *mas, unsigned long max, bool empty,
 			goto overflow;
 
 		mas->index = mas->last + 1;
-		/* Node cannot end on NULL, so it's safe to short-cut here */
 		goto again;
 	}