E:unknown volume for path [/sdcard]
There's an option to "apply update from cache" too, but /cache isn't writable without root.
I tried the downloading option (Odin) too, using Heimdall for Linux, but the recovery images I've downloaded aren't compatible with that (even after repacking from zip to tar.gz).
I also tried Bin4ry's rooting package (v33), but even after fixing the obvious bugs fixed it depends on remounting /system rw which doesn't work.
Does anyone know how to fix the unknown volume error or how to get Odin to work (preferably with Linux (Heimdall) rather than Windows)?