I'm not sure there's a non-annoying way to bridge the problem. The semantics are just so different that there's a lot of friction that needs to be handled somewhere. (What does O_DIRECT mean in this context? What happens when someone decides to store files that are never normally closed?)

In some ways, the problem mirrors OR mappers. A lot of common cases can be handled, but there are always situations where you're confronted with the fact that relational logic just doesn't map cleanly to OO (or hierarchic storage).

Since you mention the OR impedance mismatch problem, I have to link to The Vietnam of CS article: http://blogs.tedneward.com/post/the-vietnam-of-computer-scie...