Re: [Nbd] [RESEND][PATCH 0/5] nbd improvements

[Christoph Hellwig]

On Thu, Sep 15, 2016 at 02:01:59PM +0200, Wouter Verhelst wrote:
> Yes. There was some discussion on that part, and we decided that setting
> the flag doesn't hurt, but the spec also clarifies that using it on READ
> does nothing, semantically.
>
> 
> The problem is that there are clients in the wild which do set it on
> READ, so it's just a matter of "be liberal in what you accept".

Note that FUA on READ in SCSI and NVMe does have a meaning - it
requires you to bypass any sort of cache on the target.  I think it's an
wrong defintion because it mandates implementation details that aren't
observable by the initiator, but it's still the spec wording and nbd
diverges from it.  That's not nessecarily a bad thing, but a caveat to
look out for.