Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a4331366 authored by Hans Reiser's avatar Hans Reiser Committed by Linus Torvalds
Browse files

[PATCH] reiser4: add radix_tree_lookup_slot() 



Reiser4 uses radix trees to solve a trouble reiser4_readdir has serving nfs
requests.

Unfortunately, radix tree api lacks an operation suitable for modifying
existing entry.  This patch adds radix_tree_lookup_slot which returns pointer
to found item within the tree.  That location can be then updated.

Both Nick and Christoph Lameter have patches which need this as well.

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 7361f4d8

include/linux/radix-tree.h

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ do { \ 


int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);

void *radix_tree_lookup(struct radix_tree_root *, unsigned long);

void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);

void *radix_tree_delete(struct radix_tree_root *, unsigned long);

unsigned int

radix_tree_gang_lookup(struct radix_tree_root *root, void **results,

lib/radix-tree.c

+38 −13
Original line number Diff line number Diff line
@@ -281,35 +281,60 @@ int radix_tree_insert(struct radix_tree_root *root, 
}

EXPORT_SYMBOL(radix_tree_insert);



/**

 *	radix_tree_lookup    -    perform lookup operation on a radix tree

 *	@root:		radix tree root

 *	@index:		index key

 *

 *	Lookup the item at the position @index in the radix tree @root.

 */

void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)

static inline void **__lookup_slot(struct radix_tree_root *root,

				   unsigned long index)

{

	unsigned int height, shift;

	struct radix_tree_node *slot;

	struct radix_tree_node **slot;



	height = root->height;

	if (index > radix_tree_maxindex(height))

		return NULL;



	shift = (height-1) * RADIX_TREE_MAP_SHIFT;

	slot = root->rnode;

	slot = &root->rnode;



	while (height > 0) {

		if (slot == NULL)

		if (*slot == NULL)

			return NULL;



		slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];

		slot = (struct radix_tree_node **)

			((*slot)->slots +

				((index >> shift) & RADIX_TREE_MAP_MASK));

		shift -= RADIX_TREE_MAP_SHIFT;

		height--;

	}



	return slot;

	return (void **)slot;

}



/**

 *	radix_tree_lookup_slot    -    lookup a slot in a radix tree

 *	@root:		radix tree root

 *	@index:		index key

 *

 *	Lookup the slot corresponding to the position @index in the radix tree

 *	@root. This is useful for update-if-exists operations.

 */

void **radix_tree_lookup_slot(struct radix_tree_root *root, unsigned long index)

{

	return __lookup_slot(root, index);

}

EXPORT_SYMBOL(radix_tree_lookup_slot);



/**

 *	radix_tree_lookup    -    perform lookup operation on a radix tree

 *	@root:		radix tree root

 *	@index:		index key

 *

 *	Lookup the item at the position @index in the radix tree @root.

 */

void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)

{

	void **slot;



	slot = __lookup_slot(root, index);

	return slot != NULL ? *slot : NULL;

}

EXPORT_SYMBOL(radix_tree_lookup);