[PATCH v2 23/29] radix-tree: Rewrite radix_tree_tag_get

Matthew Wilcox
2016-04-14T14:17:40Z

From: Ross Zwisler <ross.zwisler@linux.intel.com>

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

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
---
lib/radix-tree.c | 44 ++++++++++++++++++--------------------------
1 file changed, 18 insertions(+), 26 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index ee56562..b1ca744 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -831,45 +831,37 @@ EXPORT_SYMBOL(radix_tree_tag_clear);
int radix_tree_tag_get(struct radix_tree_root *root,
unsigned long index, unsigned int tag)
{
- unsigned int height, shift;
- struct radix_tree_node *node;
+ struct radix_tree_node *node, *parent;
+ unsigned long maxindex;
+ unsigned int shift;

- /* check the root's tag bit */
if (!root_tag_get(root, tag))
return 0;

- node = rcu_dereference_raw(root->rnode);
+ shift = radix_tree_load_root(root, &node, &maxindex);
+ if (index > maxindex)
+ return 0;
if (node == NULL)
return 0;

- if (!radix_tree_is_indirect_ptr(node))
- return (index == 0);
- node = indirect_to_ptr(node);
-
- height = node->path & RADIX_TREE_HEIGHT_MASK;
- if (index > radix_tree_maxindex(height))
- return 0;
+ while (radix_tree_is_indirect_ptr(node)) {
+ int offset;

- shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
+ shift -= RADIX_TREE_MAP_SHIFT;
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;

- for ( ; ; ) {
- int offset;
+ parent = indirect_to_ptr(node);
+ offset = radix_tree_descend(parent, &node, offset);

- if (node == NULL)
+ if (!node)
return 0;
- node = indirect_to_ptr(node);
-
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
- if (!tag_get(node, tag, offset))
+ if (!tag_get(parent, tag, offset))
return 0;
- if (height == 1)
- return 1;
- node = rcu_dereference_raw(node->slots[offset]);
- if (!radix_tree_is_indirect_ptr(node))
- return 1;
- shift -= RADIX_TREE_MAP_SHIFT;
- height--;
+ if (node == RADIX_TREE_RETRY)
+ break;
}
+
+ return 1;
}
EXPORT_SYMBOL(radix_tree_tag_get);

--
2.8.0.rc3