[PATCH v2 17/29] radix-tree: Rewrite __radix_tree_lookup

Matthew Wilcox
2016-04-14T14:19:54Z

Use the new multi-order support functions to rewrite __radix_tree_lookup()

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
lib/radix-tree.c | 48 ++++++++++++++++--------------------------------
1 file changed, 16 insertions(+), 32 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a1ba417..f14ada9 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -634,44 +634,28 @@ void *__radix_tree_lookup(struct radix_tree_root *root, unsigned long index,
struct radix_tree_node **nodep, void ***slotp)
{
struct radix_tree_node *node, *parent;
- unsigned int height, shift;
+ unsigned long maxindex;
+ unsigned int shift;
void **slot;

- node = rcu_dereference_raw(root->rnode);
- if (node == NULL)
- return NULL;
-
- if (!radix_tree_is_indirect_ptr(node)) {
- if (index > 0)
- return NULL;
-
- if (nodep)
- *nodep = NULL;
- if (slotp)
- *slotp = (void **)&root->rnode;
- return node;
- }
- node = indirect_to_ptr(node);
-
- height = node->path & RADIX_TREE_HEIGHT_MASK;
- if (index > radix_tree_maxindex(height))
+ restart:
+ parent = NULL;
+ slot = (void **)&root->rnode;
+ shift = radix_tree_load_root(root, &node, &maxindex);
+ if (index > maxindex)
return NULL;

- shift = (height-1) * RADIX_TREE_MAP_SHIFT;
-
- do {
- parent = node;
- slot = node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK);
- node = rcu_dereference_raw(*slot);
- if (node == NULL)
- return NULL;
- if (!radix_tree_is_indirect_ptr(node))
- break;
- node = indirect_to_ptr(node);
+ while (radix_tree_is_indirect_ptr(node)) {
+ unsigned offset;

+ if (node == RADIX_TREE_RETRY)
+ goto restart;
+ parent = indirect_to_ptr(node);
shift -= RADIX_TREE_MAP_SHIFT;
- height--;
- } while (height > 0);
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ offset = radix_tree_descend(parent, &node, offset);
+ slot = parent->slots + offset;
+ }

if (nodep)
*nodep = parent;
--
2.8.0.rc3