[PATCH 1/3] radix-tree: Implement function radix_tree_gang_tag_if_tagged

Jan Kara
2010-02-11T23:07:00Z

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

Signed-off-by: Jan Kara <jack@suse.cz>
---
include/linux/radix-tree.h | 3 ++
lib/radix-tree.c | 82 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 85 insertions(+), 0 deletions(-)

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index c5da749..41fa087 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -185,6 +185,9 @@ 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_gang_tag_if_tagged(struct radix_tree_root *root,
+ unsigned long first_index, unsigned long last_index,
+ 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)
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 92cdd99..d821a17 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -610,6 +610,88 @@ int radix_tree_tag_get(struct radix_tree_root *root,
EXPORT_SYMBOL(radix_tree_tag_get);

/**
+ * radix_tree_gang_tag_if_tagged - for each item in given range set given
+ * tag if item has another tag set
+ * @root: radix tree root
+ * @first_index: starting index of a range to scan
+ * @last_index: last index of a range to scan
+ * @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.
+ * For each item in the range if iftag is set, the function sets also
+ * settag.
+ *
+ * The function returns number of leaves where the tag was set.
+ */
+unsigned long radix_tree_gang_tag_if_tagged(struct radix_tree_root *root,
+ unsigned long first_index, unsigned long last_index,
+ unsigned int iftag, unsigned int settag)
+{
+ unsigned int height = root->height, shift;
+ unsigned long tagged = 0, index = first_index;
+ struct radix_tree_node *open_slots[height], *slot;
+
+ last_index = min(last_index, radix_tree_maxindex(height));
+ if (first_index > last_index)
+ return 0;
+ if (!root_tag_get(root, iftag))
+ return 0;
+ if (height == 0) {
+ 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;
+ 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);
+
+ return tagged;
+}
+EXPORT_SYMBOL(radix_tree_gang_tag_if_tagged);
+
+
+/**
* radix_tree_next_hole - find the next hole (not-present entry)
* @root: tree root
* @index: index key
--
1.6.4.2