only allow unprivileged passthrough for commands without effects v4

[Christoph Hellwig]

On Wed, Dec 28, 2022 at 09:04:28AM -0700, Keith Busch wrote:
> Series looks good to go.
> 
> Reviewed-by: Keith Busch <kbusch at kernel.org>
> 
> Unless you're already on it, I'd be happy to take a shot at the
> improvements we discussed earlier for the next merge window.

I still have the current versions of those stashed away from the
last iteration, but as they'd need a rebase anyway I'll happily leave
that to you.