Re: kexportfs features

Anders Hammarquist (iko@netg.se)
Sat, 12 Sep 1998 23:24:03 +0200

>>>>"G. Allen Morris III" said:
>> There are several improvements that I need to be made to kexportfs
>> IMHO.
>
>4. There needs to be a `devived export' list. The problem is that if there
>is a wildcard export like :/. If host `A' mounts / and then
>`kexportfs -au' is executed followed by a `kexportfs -a' host `A' will
>get a `Stale file handle' error until `kexport A:/' is executed.
>Anyone have ideas on the best way to handle this problem?

I've thought some about this, and the neatest (though not neccesarily
easiest) way I see is to separate the export list into an in-kernel
cache and an authorative user-mode master list handled by mountd and
exportfs. What I mean by this is to have the kernel ask mountd about
any getfh call it receives that is not in the in-kernel cache, and
reject or allow it based on what mountd responds. In addition to
avoiding possible race conditions at boot and the like, it would let
us have very large export lists without using up lots of kernel
memory. (Credit for some of these ideas is due Steven N. Hirsch
<shirsch@adelphia.net>)

The other way is to do it the ONC way and accept any good filehandle
and not bother with the export list. Some might consider the security
of this approach less than ideal though.

Regards,
/Anders

-- 
 -- Of course I'm crazy, but that doesn't mean I'm wrong.
Anders Hammarquist   |       Mud at Kingdoms        | iko@netg.se
NetGuide Scandinavia |   telnet kingdoms.se 1812    | Fax: +46 31 50 79 39
http://www.netg.se   |                              | Tel: +46 31 50 79 40


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