[PATCH v2 10/19] maple_tree: micro optimisation of mas_wr_store_type()

[Liam R. Howlett (Oracle)]

Use three new local booleans instead of reading other structures.  This
has shown an increase of 0.62% on a 2048 entry tree of height 4.

Signed-off-by: Liam R. Howlett (Oracle) <liam@xxxxxxxxxxxxx>
---
 lib/maple_tree.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 1c96b3a5dab60..999a1d095e369 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3736,6 +3736,9 @@ static inline enum store_type mas_wr_store_type(struct ma_wr_state *wr_mas)
 {
 	struct ma_state *mas = wr_mas->mas;
 	unsigned char new_end;
+	bool appending;
+	bool one_slot;
+	bool in_rcu;
 
 	if (unlikely(mas_is_none(mas) || mas_is_ptr(mas)))
 		return wr_store_root;
@@ -3755,21 +3758,30 @@ static inline enum store_type mas_wr_store_type(struct ma_wr_state *wr_mas)
 		return wr_new_root;
 
 	new_end = mas_wr_new_end(wr_mas);
+	in_rcu = mt_in_rcu(mas->tree);
+	appending = mas->offset == mas->end;
+	one_slot = wr_mas->offset_end - mas->offset == 1;
+
 	/* Potential spanning rebalance collapsing a node */
 	if (new_end < mt_min_slots[wr_mas->type]) {
 		if (!mte_is_root(mas->node))
 			return  wr_rebalance;
+		if (!in_rcu) {
+			if (appending)
+				return wr_append;
+			else if (mas->end == new_end && one_slot)
+				return wr_slot_store;
+		}
 		return wr_node_store;
 	}
 
 	if (new_end >= mt_slots[wr_mas->type])
 		return wr_split_store;
 
-	if (!mt_in_rcu(mas->tree) && (mas->offset == mas->end))
+	if (!in_rcu && appending)
 		return wr_append;
 
-	if ((new_end == mas->end) && (!mt_in_rcu(mas->tree) ||
-		(wr_mas->offset_end - mas->offset == 1)))
+	if (new_end == mas->end && (!in_rcu || one_slot))
 		return wr_slot_store;
 
 	return wr_node_store;
-- 
2.47.3