How to map a single unmapped BIO?

[Owens, Keith]

I have a geom that sometimes (very rarely) needs to modify the data in an unmapped BIO. Completely removing unmapped support from the entire geom is overkill. What is the best way of converting a single unmapped BIO to a mapped address so I can access the data?

Basically I want g_io_transient_map_bio(), but that function is static. Duplicating that code in my geom is not elegant.