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Commit ebf8aa44 authored by Jan Kara's avatar Jan Kara Committed by Linus Torvalds
Browse files

radix-tree: omplement function radix_tree_range_tag_if_tagged 



Implement function for setting one tag if another tag is set for each item
in given range.

Signed-off-by: default avatarJan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 44ab57a0

include/linux/radix-tree.h

+4 −0
Original line number Diff line number Diff line
@@ -192,6 +192,10 @@ unsigned int 
radix_tree_gang_lookup_tag_slot(struct radix_tree_root *root, void ***results,

		unsigned long first_index, unsigned int max_items,

		unsigned int tag);

unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,

		unsigned long *first_indexp, unsigned long last_index,

		unsigned long nr_to_tag,

		unsigned int fromtag, unsigned int totag);

int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag);



static inline void radix_tree_preload_end(void)

lib/radix-tree.c

+94 −0
Original line number Diff line number Diff line
@@ -608,6 +608,100 @@ int radix_tree_tag_get(struct radix_tree_root *root, 
}

EXPORT_SYMBOL(radix_tree_tag_get);



/**

 * radix_tree_range_tag_if_tagged - for each item in given range set given

 *				   tag if item has another tag set

 * @root:		radix tree root

 * @first_indexp:	pointer to a starting index of a range to scan

 * @last_index:		last index of a range to scan

 * @nr_to_tag:		maximum number items to tag

 * @iftag:		tag index to test

 * @settag:		tag index to set if tested tag is set

 *

 * This function scans range of radix tree from first_index to last_index

 * (inclusive).  For each item in the range if iftag is set, the function sets

 * also settag. The function stops either after tagging nr_to_tag items or

 * after reaching last_index.

 *

 * The function returns number of leaves where the tag was set and sets

 * *first_indexp to the first unscanned index.

 */

unsigned long radix_tree_range_tag_if_tagged(struct radix_tree_root *root,

		unsigned long *first_indexp, unsigned long last_index,

		unsigned long nr_to_tag,

		unsigned int iftag, unsigned int settag)

{

	unsigned int height = root->height, shift;

	unsigned long tagged = 0, index = *first_indexp;

	struct radix_tree_node *open_slots[height], *slot;



	last_index = min(last_index, radix_tree_maxindex(height));

	if (index > last_index)

		return 0;

	if (!nr_to_tag)

		return 0;

	if (!root_tag_get(root, iftag)) {

		*first_indexp = last_index + 1;

		return 0;

	}

	if (height == 0) {

		*first_indexp = last_index + 1;

		root_tag_set(root, settag);

		return 1;

	}



	shift = (height - 1) * RADIX_TREE_MAP_SHIFT;

	slot = radix_tree_indirect_to_ptr(root->rnode);



	for (;;) {

		int offset;



		offset = (index >> shift) & RADIX_TREE_MAP_MASK;

		if (!slot->slots[offset])

			goto next;

		if (!tag_get(slot, iftag, offset))

			goto next;

		tag_set(slot, settag, offset);

		if (height == 1) {

			tagged++;

			goto next;

		}

		/* Go down one level */

		height--;

		shift -= RADIX_TREE_MAP_SHIFT;

		open_slots[height] = slot;

		slot = slot->slots[offset];

		continue;

next:

		/* Go to next item at level determined by 'shift' */

		index = ((index >> shift) + 1) << shift;

		if (index > last_index)

			break;

		if (tagged >= nr_to_tag)

			break;

		while (((index >> shift) & RADIX_TREE_MAP_MASK) == 0) {

			/*

			 * We've fully scanned this node. Go up. Because

			 * last_index is guaranteed to be in the tree, what

			 * we do below cannot wander astray.

			 */

			slot = open_slots[height];

			height++;

			shift += RADIX_TREE_MAP_SHIFT;

		}

	}

	/*

	 * The iftag must have been set somewhere because otherwise

	 * we would return immediated at the beginning of the function

	 */

	root_tag_set(root, settag);

	*first_indexp = index;



	return tagged;

}

EXPORT_SYMBOL(radix_tree_range_tag_if_tagged);





/**

 *	radix_tree_next_hole    -    find the next hole (not-present entry)

 *	@root:		tree root