> -----Original Message----- > From: Christoph Hellwig [mailto:h...@infradead.org] > Sent: Thursday, January 26, 2017 6:52 AM > To: Cathy Avery <cav...@redhat.com> > Cc: KY Srinivasan <k...@microsoft.com>; h...@infradead.org; Haiyang Zhang > <haiya...@microsoft.com>; j...@linux.vnet.ibm.com; > martin.peter...@oracle.com; dan.carpen...@oracle.com; > de...@linuxdriverproject.org; linux-kernel@vger.kernel.org; linux- > s...@vger.kernel.org; f...@redhat.com > Subject: Re: [PATCH v2 0/2] scsi: storvsc: Add support for FC lightweight > host. > > On Thu, Jan 26, 2017 at 08:38:58AM -0500, Cathy Avery wrote: > > Included in the current storvsc driver for Hyper-V is the ability > > to access luns on an FC fabric via a virtualized fiber channel > > adapter exposed by the Hyper-V host. This was done to provide an > > interface for existing customer tools that was more consistent with > > a conventional FC device. The driver attaches to the FC transport > > to allow host and port names to be published under > > /sys/class/fc_host/hostX. > > > > A problem arose when attaching to the FC transport. The scsi_scan code > > attempts to call fc_user_scan which has basically become a no-op > > due to the virtualized nature of the FC host > > ( missing rports, vports, etc ). At this point you cannot refresh > > the scsi bus after mapping or unmapping luns on the SAN without > > a reboot. > > I don't think a device without rports or vports is a FC device, plain and > simple. So as far as I'm concerned we should remove the code from storvsc > that pretends to be FC, and not add it to virtio to start with. > > And again I think leightweight is a very confusing name - > what exactly is leight or heavy? It's really fake or dummy > in the current version.
Windows has chosen this model for virtualizing FC devices to the guest - without rports (or vports). As I noted in my earlier email, James came up with this notion of a lightweight template almost a year ago. We can certainly pick a more appropriate name and include better documentation. > > > > > 2) Removes an original workaround dealing with replacing > > the eh_timed_out function. Patch 1 will not set the > > scsi_transport_template.eh_timed_out function directly during > > lightweight fc_attach_transport(). It instead relies on > > whatever was indicated as the scsi_host_template timeout handler > > during scsi_times_out() scsi_error.c. So the workaround is > > no longer necessary. > > Can you send a patch that gets rid of the transport class timeout handler > entirely? I think it's simply the wrong layering we have here - the > driver needs to be in control of timeouts, and if it wants it can > optionally call into library code in the transport class. We will address this concern. > > > FYI, all the long-term relevant explanation need to go into the patches > themselves (patch description or code comments), not in the cover > letter. We will address this. Regards, K. Y
