Bug#78011: storeio (in)activation (was: Re: CDROM lock)

[Roland McGrath]

> This is not good enough, IMHO. Alexey Dejneka sent in a patch for gnumach
> that does the same, and it works just fine. But after doing:
> 
> settrans -ag /cdrom
> 
> you have to do
> 
> settrans -ag /dev/hd3
> 
> (or whatever your CD ROM device is) as well, or the CD ROM remains busy.

Ok.  I think there are two lines of inquiry here.  Firstly, storeio
definitely needs to be fixed; this is a bug.  What storeio should do is
keep track of the number of peropens and when there are no live peropens
for the device, it should deactivate the store.  (Incidentally, I think
that the changes I made to close and reopen the store should instead just
clear/set the STORE_INACTIVE flag after opening with STORE_INACTIVE.)
That will make things work right when everything is well-behaved.

For another level of robustness, we might want to think about having a
revoke-like call at the kernel device level.