(a) General rule: Perfection by filing. Except as otherwise provided in subsection (b) of this section and section 9-312(b), a financing statement must be filed to perfect all security interests and agricultural liens.
(b) Exceptions: Filing not necessary. The filing of a financing statement is not necessary to perfect a security interest:
(1) That is perfected under section 9-308(d), (e), (f) or (g);