Commit d604c324 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

radix-tree: introduce radix_tree_replace_clear_tags() 



In addition to replacing the entry, we also clear all associated tags.
This is really a one-off special for page_cache_tree_delete() which had
far too much detailed knowledge about how the radix tree works.

For efficiency, factor node_tag_clear() out of radix_tree_tag_clear() It
can be used by radix_tree_delete_item() as well as
radix_tree_replace_clear_tags().

Signed-off-by: default avatarMatthew Wilcox <willy@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>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 89148aa4

include/linux/radix-tree.h

+6 −3
Original line number Diff line number Diff line
@@ -281,9 +281,12 @@ bool __radix_tree_delete_node(struct radix_tree_root *root, 
			      struct radix_tree_node *node);

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

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

unsigned int

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

			unsigned long first_index, unsigned int max_items);

struct radix_tree_node *radix_tree_replace_clear_tags(

				struct radix_tree_root *root,

				unsigned long index, void *entry);

unsigned int radix_tree_gang_lookup(struct radix_tree_root *root,

			void **results, unsigned long first_index,

			unsigned int max_items);

unsigned int radix_tree_gang_lookup_slot(struct radix_tree_root *root,

			void ***results, unsigned long *indices,

			unsigned long first_index, unsigned int max_items);

lib/radix-tree.c

+47 −29
Original line number Diff line number Diff line
@@ -740,6 +740,26 @@ void *radix_tree_tag_set(struct radix_tree_root *root, 
}

EXPORT_SYMBOL(radix_tree_tag_set);



static void node_tag_clear(struct radix_tree_root *root,

				struct radix_tree_node *node,

				unsigned int tag, unsigned int offset)

{

	while (node) {

		if (!tag_get(node, tag, offset))

			return;

		tag_clear(node, tag, offset);

		if (any_tag_set(node, tag))

			return;



		offset = node->offset;

		node = node->parent;

	}



	/* clear the root's tag bit */

	if (root_tag_get(root, tag))

		root_tag_clear(root, tag);

}



/**

 *	radix_tree_tag_clear - clear a tag on a radix tree node

 *	@root:		radix tree root
@@ -776,28 +796,9 @@ void *radix_tree_tag_clear(struct radix_tree_root *root, 
		offset = radix_tree_descend(parent, &node, offset);

	}



	if (node == NULL)

		goto out;



	index >>= shift;



	while (parent) {

		if (!tag_get(parent, tag, offset))

			goto out;

		tag_clear(parent, tag, offset);

		if (any_tag_set(parent, tag))

			goto out;



		index >>= RADIX_TREE_MAP_SHIFT;

		offset = index & RADIX_TREE_MAP_MASK;

		parent = parent->parent;

	}



	/* clear the root's tag bit */

	if (root_tag_get(root, tag))

		root_tag_clear(root, tag);

	if (node)

		node_tag_clear(root, parent, tag, offset);



out:

	return node;

}

EXPORT_SYMBOL(radix_tree_tag_clear);
@@ -1525,14 +1526,9 @@ void *radix_tree_delete_item(struct radix_tree_root *root, 


	offset = get_slot_offset(node, slot);



	/*

	 * Clear all tags associated with the item to be deleted.

	 * This way of doing it would be inefficient, but seldom is any set.

	 */

	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {

		if (tag_get(node, tag, offset))

			radix_tree_tag_clear(root, index, tag);

	}

	/* Clear all tags associated with the item to be deleted.  */

	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)

		node_tag_clear(root, node, tag, offset);



	delete_sibling_entries(node, node_to_entry(slot), offset);

	node->slots[offset] = NULL;
@@ -1559,6 +1555,28 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index) 
}

EXPORT_SYMBOL(radix_tree_delete);



struct radix_tree_node *radix_tree_replace_clear_tags(

			struct radix_tree_root *root,

			unsigned long index, void *entry)

{

	struct radix_tree_node *node;

	void **slot;



	__radix_tree_lookup(root, index, &node, &slot);



	if (node) {

		unsigned int tag, offset = get_slot_offset(node, slot);

		for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)

			node_tag_clear(root, node, tag, offset);

	} else {

		/* Clear root node tags */

		root->gfp_mask &= __GFP_BITS_MASK;

	}



	radix_tree_replace_slot(slot, entry);

	return node;

}



/**

 *	radix_tree_tagged - test whether any items in the tree are tagged

 *	@root:		radix tree root

mm/filemap.c

+3 −20
Original line number Diff line number Diff line
@@ -114,14 +114,11 @@ static void page_cache_tree_delete(struct address_space *mapping, 
				   struct page *page, void *shadow)

{

	struct radix_tree_node *node;

	unsigned long index;

	unsigned int offset;

	unsigned int tag;

	void **slot;



	VM_BUG_ON(!PageLocked(page));



	__radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);

	node = radix_tree_replace_clear_tags(&mapping->page_tree, page->index,

								shadow);



	if (shadow) {

		mapping->nrexceptional++;
@@ -135,23 +132,9 @@ static void page_cache_tree_delete(struct address_space *mapping, 
	}

	mapping->nrpages--;



	if (!node) {

		/* Clear direct pointer tags in root node */

		mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;

		radix_tree_replace_slot(slot, shadow);

	if (!node)

		return;

	}



	/* Clear tree tags for the removed page */

	index = page->index;

	offset = index & RADIX_TREE_MAP_MASK;

	for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {

		if (test_bit(offset, node->tags[tag]))

			radix_tree_tag_clear(&mapping->page_tree, index, tag);

	}



	/* Delete page, swap shadow entry */

	radix_tree_replace_slot(slot, shadow);

	workingset_node_pages_dec(node);

	if (shadow)

		workingset_node_shadows_inc(node);

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