[PATCH v2 1/2] maple_tree: Add mas_is_active() to detect in-tree walks

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

Instead of constantly checking each possibility of the maple state,
create a fast path that will skip over checking unlikely states.

Cc: stable@vger.kernel.org
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
---
 include/linux/maple_tree.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/maple_tree.h b/include/linux/maple_tree.h
index e41c70ac7744..f66f5f78f8cf 100644
--- a/include/linux/maple_tree.h
+++ b/include/linux/maple_tree.h
@@ -511,6 +511,15 @@ static inline bool mas_is_paused(const struct ma_state *mas)
 	return mas->node == MAS_PAUSE;
 }
 
+/* Check if the mas is pointing to a node or not */
+static inline bool mas_is_active(struct ma_state *mas)
+{
+	if ((unsigned long)mas->node >= MAPLE_RESERVED_RANGE)
+		return true;
+
+	return false;
+}
+
 /**
  * mas_reset() - Reset a Maple Tree operation state.
  * @mas: Maple Tree operation state.
-- 
2.40.1