[PATCH v2 24/29] maple_tree: Add cp_converged() helper

["Liam R. Howlett" <Liam.Howlett@oracle.com>]

When the maple copy node converges into a single entry, then certain
operations can stop ascending the tree.

This is used more later.

Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 lib/maple_tree.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 22f52a9b26a9e..191b855575650 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -3485,6 +3485,16 @@ static inline bool cp_is_new_root(struct maple_copy *cp, struct ma_state *mas)
 	return true;
 }
 
+static inline bool cp_converged(struct maple_copy *cp, struct ma_state *mas,
+				struct ma_state *sib)
+{
+	if (cp->d_count != 1 || sib->end)
+		return false;
+
+	cp->dst[0].node->parent = ma_parent_ptr(mas_mn(mas)->parent);
+	return true;
+}
+
 /*
  * spanning_ascend() - See if a spanning store operation has to keep walking up
  * the tree
@@ -3567,10 +3577,8 @@ static inline bool rebalance_ascend(struct maple_copy *cp,
 	if (cp_is_new_root(cp, mas))
 		return false;
 
-	if (cp->d_count == 1 && !sib->end) {
-		cp->dst[0].node->parent = ma_parent_ptr(mas_mn(mas)->parent);
+	if (cp_converged(cp, mas, sib))
 		return false;
-	}
 
 	cp->height++;
 	copy_tree_location(parent, mas);
-- 
2.47.3