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

[Christoph Hellwig]

On Thu, Sep 15, 2016 at 12:09:28PM +0100, Alex Bligh wrote:
> A more general point is that with multiple queues requests
> may be processed in a different order even by those servers that
> currently process the requests in strict order, or in something
> similar to strict order. The server is permitted by the spec
> (save as mandated by NBD_CMD_FLUSH and NBD_CMD_FLAG_FUA) to
> process commands out of order anyway, but I suspect this has
> to date been little tested.

The Linux kernel does not assume any synchroniztion between block I/O
commands.  So any sort of synchronization a protocol does is complete
overkill for us.