Re: [RFC 01/11] iscsi-target: Add iscsit_transport API template

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

On Fri, 2013-03-08 at 14:36 +0200, Or Gerlitz wrote:
> On Fri, Mar 8, 2013 at 6:14 AM, Roland Dreier <roland@kernel.org> wrote:
> > Nicholas A. Bellinger <nab@linux-iscsi.org> wrote:
> > > +EXPORT_SYMBOL(iscsit_get_transport);
> 
> > It's not clear to me why this needs to be exported.  Who would use it
> > outside the core iscsi target module?
> 
> Yep, as Nic noted, we're adding here an iscsi transport concept e.g in
> the same manner Mike did libiscsi back in 2005/6 when the iser
> initiator was pushed. This allows for multiple iscsi flavours to use a
> common code  for common functionality. In the initiator area initially
> there were iscsi tcp and iser, later few iscsi HW offloads were merged
> too. Same story here. I think that the point is whether or not these
> APIs are needed, since once we agree on that, we need an header file
> and exporting of functions. As libiscsi.h resided under include/ it
> makes sense to me for this include to be located there too.

So my main concern with putting iscsit_transport definitions into
include/target/iscsi/ is the number of dependencies required from
iscsi_target_core.h.

Currently with iscsi_cmd embedded into isert_cmd, this will require most
existing iscsi_target_core.h definitions to be pushed out into
include/target/iscsi/.  This also includes some namespace conflicts
between libiscsi.h and iscsi_target_core.h, but those can be solved
easily enough.

I'm still leaning towards just keeping iscsi_transport.h definitions
local to drivers/target/iscsi, if there is really not going to be other
drivers aside from ib_isert that end up using it.  If there was interest
in traditional iscsi-target HW offloads using this interface then the
story would be different, but every HW offload that I've seen thus far
using LIO is based on out-of-tree NIC code to start.

--nab







 

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