EXPORT_SYMBOL radix_tree_replace_slot

It will be used in drivers/md/raid5-cache.c

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 84812a9..72fab49 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1102,6 +1102,7 @@
 {
 	replace_slot(root, NULL, slot, item, true);
 }
+EXPORT_SYMBOL(radix_tree_replace_slot);
 
 /**
  * radix_tree_iter_replace - replace item in a slot