radix-tree: rewrite __radix_tree_lookup

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>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index a1ba4173007161c316193b481a3c387d2257d00c..f14ada9830ca128bda6a0d097f2a8ba2698435f4 100644 (file)
--- 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;