Read-only medium/device detection

[Martin]

Hi,

when I mount a device (or medium) which is read-only without
the -r option, I get lots of troubles when shutting down later.
Syncer does not write all vnodes/blocks to disk. This happened
to me with a write protected floppy disk (-t msdos) and a
CD-R (-t ufs).

It seems to me that read-only state of a file system is being
initially setup according to the type of the file system.
Wouldn't it be more appropriate to detect the medium/device
capabilities to setup it read-only automatically if needed?

Martin