[PATCH v2 13/29] radix-tree: Introduce radix_tree_load_root()

Matthew Wilcox
2016-04-14T14:17:56Z

All the tree walking functions start with some variant of this code;
centralise it in one place so we're not chasing subtly different bugs
everywhere.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
lib/radix-tree.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 6900f7b..272ce81 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -405,6 +405,29 @@ static inline unsigned long radix_tree_maxindex(unsigned int height)
return height_to_maxindex[height];
}

+static inline unsigned long node_maxindex(struct radix_tree_node *node)
+{
+ return radix_tree_maxindex(node->path & RADIX_TREE_HEIGHT_MASK);
+}
+
+static unsigned radix_tree_load_root(struct radix_tree_root *root,
+ struct radix_tree_node **nodep, unsigned long *maxindex)
+{
+ struct radix_tree_node *node = rcu_dereference_raw(root->rnode);
+
+ *nodep = node;
+
+ if (likely(radix_tree_is_indirect_ptr(node))) {
+ node = indirect_to_ptr(node);
+ *maxindex = node_maxindex(node);
+ return (node->path & RADIX_TREE_HEIGHT_MASK) *
+ RADIX_TREE_MAP_SHIFT;
+ }
+
+ *maxindex = 0;
+ return 0;
+}
+
/*
* Extend a radix tree so it can store key @index.
*/
--
2.8.0.rc3