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radix-tree: rewrite __radix_tree_lookup

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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>
This commit is contained in:
Matthew Wilcox 2016-05-20 17:02:20 -07:00 committed by Linus Torvalds
parent afe0e395b6
commit 858299544e
1 changed files with 16 additions and 32 deletions
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48
lib/radix-tree.c
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@ -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)
restart:
parent = NULL;
slot = (void **)&root->rnode;
shift = radix_tree_load_root(root, &node, &maxindex);
if (index > maxindex)
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))
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;