f2fs: avoid mark_inode_dirty

Let's check inode's dirtiness before calling mark_inode_dirty.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/extent_cache.c

@@ -172,7 +172,7 @@ static void __drop_largest_extent(struct inode *inode,
 
 	if (fofs < largest->fofs + largest->len && fofs + len > largest->fofs) {
 		largest->len = 0;
-		mark_inode_dirty_sync(inode);
+		f2fs_mark_inode_dirty_sync(inode);
 	}
 }