should mount -u fail or silently ignore options?

[Jaakko Heinonen]

On 2012-01-22, Rick Macklem wrote:
> There is a bug in the NFS clients, where a
> "mount -u -o udp /mnt" will cause any threads
> that have an RPC in progress to hang, if the
> mount previously was using too large an rsize/wsize.

Does the hang occur if the UDP transport was already used?

> This case can easily be detected in nfs_mount().
> 
> However, my question is...
> - Should the "mount -u" fail and return an error
> OR
>   Silently ignore the "udp" option and return ok.

Depending on the answer to the question above, IMHO the best solution
would be to return an error if user tries to change TCP to UDP but
accept the "udp" option if UDP transport is already active. I don't know
about potential problems with root nfs.

-- 
Jaakko