Does unmount() sync dirty buffers

Hello, When we unmount a file system with the umount command or the umount() system call, does the kernel sync the dirty buffers before the file system is unmounted?I am assuming that the file system is not 'busy' (i.e no open files etc) and no force options are specified. When I did a walk-through of do_umount() call in fs/namespace.c, I could not find calls to sync any dirty pages that might exist. Thanks! Ravi