f2fs: clean up with clear_radix_tree_dirty_tag

Introduce clear_radix_tree_dirty_tag to include common codes for cleanup.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 0546421..d34e86a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2589,6 +2589,17 @@
 #endif
 };
 
+void clear_radix_tree_dirty_tag(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mapping->tree_lock, flags);
+	radix_tree_tag_clear(&mapping->page_tree, page_index(page),
+					PAGECACHE_TAG_DIRTY);
+	spin_unlock_irqrestore(&mapping->tree_lock, flags);
+}
+
 int __init f2fs_init_post_read_processing(void)
 {
 	bio_post_read_ctx_cache = KMEM_CACHE(bio_post_read_ctx, 0);