[RFC PATCH 3/5] radix-tree: introduce radix_tree_[next/prev]_present()

[Joonsoo Kim <iamjoonsoo.kim@lge.com>]

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index ffc444c..045b325 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -230,6 +230,10 @@ unsigned long radix_tree_next_hole(struct radix_tree_root *root,
 				unsigned long index, unsigned long max_scan);
 unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
 				unsigned long index, unsigned long max_scan);
+unsigned long radix_tree_next_present(struct radix_tree_root *root,
+				unsigned long index, unsigned long max_scan);
+unsigned long radix_tree_prev_present(struct radix_tree_root *root,
+				unsigned long index, unsigned long max_scan);
 int radix_tree_preload(gfp_t gfp_mask);
 void radix_tree_init(void);
 void *radix_tree_tag_set(struct radix_tree_root *root,
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index e796429..e02e3b8 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -984,6 +984,40 @@ unsigned long radix_tree_prev_hole(struct radix_tree_root *root,
 }
 EXPORT_SYMBOL(radix_tree_prev_hole);
 
+unsigned long radix_tree_next_present(struct radix_tree_root *root,
+				unsigned long index, unsigned long max_scan)
+{
+	unsigned long i;
+
+	for (i = 0; i < max_scan; i++) {
+		if (radix_tree_lookup(root, index))
+			break;
+		index++;
+		if (index == 0)
+			break;
+	}
+
+	return index;
+}
+EXPORT_SYMBOL(radix_tree_next_present);
+
+unsigned long radix_tree_prev_present(struct radix_tree_root *root,
+				   unsigned long index, unsigned long max_scan)
+{
+	unsigned long i;
+
+	for (i = 0; i < max_scan; i++) {
+		if (radix_tree_lookup(root, index))
+			break;
+		index--;
+		if (index == ULONG_MAX)
+			break;
+	}
+
+	return index;
+}
+EXPORT_SYMBOL(radix_tree_prev_present);
+
 /**
  *	radix_tree_gang_lookup - perform multiple lookup on a radix tree
  *	@root:		radix tree root
-- 
1.7.9.5

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