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

On Thu, Sep 15, 2016 at 01:29:36PM +0200, Wouter Verhelst wrote:

Yes, and that is why I was asking about this. If the write barriers
are expected to be shared across connections, we have a problem. If,
however, they are not, then it doesn't matter that the commands may be
processed out of order.

There is no such thing as a write barrier in the Linux kernel.  We'd
much prefer protocols not to introduce any pointless synchronization
if we can avoid it.