Re: [PATCH v15 7/9] nvmet-passthru: Add passthru code to process commands

[Sagi Grimberg]

> > Add passthru command handling capability for the NVMeOF target and
> > export passthru APIs which are used to integrate passthru
> > code with nvmet-core.
> >
> > The new file passthru.c handles passthru cmd parsing and execution.
> > In the passthru mode, we create a block layer request from the nvmet
> > request and map the data on to the block layer request.
> >
> > Admin commands and features are on a white list as there are a number
> > of each that don't make too much sense with passthrough. We use a
> > white list so that new commands can be considered before being blindly
> > passed through. In both cases, vendor specific commands are always
> > allowed.
> >
> > We also blacklist reservation IO commands as the underlying device
> > cannot differentiate between multiple hosts behind a fabric.
>
> I'm still not so happy about having to look up the namespace and still
> wonder if we should generalize the connect_q to a passthrough_q.  But
> I guess we can do that later and then reduce some of the exports here..

That is a neat idea! should be easy to do (and we can then lose the host
xarray stuff). I don't mind having it on a later patch, but it should be
easy enough to do even before...