[PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[K. Y. Srinivasan]

The default user scan function associated with FC (fc_user_scan)
is not suitable for FC hosts on Hyper-V since we don't have
an rport associated with FC host on Hyper-V . Set it to NULL so we can
support manual scan of FC targets on Hyper-V.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Tested-by: Long Li <longli@microsoft.com>
Reviewed-by: Long Li <longli@microsoft.com>
---
 drivers/scsi/storvsc_drv.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 132b168..8aec590 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1776,6 +1776,12 @@ static int __init storvsc_drv_init(void)
 	 * Install Hyper-V specific timeout handler.
 	 */
 	fc_transport_template->eh_timed_out = storvsc_eh_timed_out;
+	/*
+	 * The default user scan function associated with FC (fc_user_scan)
+	 * is not suitable for FC hosts on Hyper-V. Set it to NULL so we can
+	 * support manual scan of FC targets on Hyper-V.
+	 */
+	fc_transport_template->user_scan = NULL;
 #endif
 
 	ret = vmbus_driver_register(&storvsc_drv);
-- 
1.7.4.1

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[Christoph Hellwig]

On Sat, Mar 12, 2016 at 01:52:48PM -0800, K. Y. Srinivasan wrote:
> The default user scan function associated with FC (fc_user_scan)
> is not suitable for FC hosts on Hyper-V since we don't have
> an rport associated with FC host on Hyper-V . Set it to NULL so we can
> support manual scan of FC targets on Hyper-V.

This isn't really how the FC transport class in intended to work, but
neither is the eh_timed_out (which I haven't seen in my tree yet).

It sounds like storvsc simply shouldn't attach to the FC transport
if it doesn't actually look like a FC HBA.

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: Christoph Hellwig [mailto:hch@infradead.org]
> Sent: Tuesday, March 15, 2016 6:40 AM
> To: KY Srinivasan <kys@microsoft.com>
> Cc: gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; ohering@suse.com;
> jbottomley@parallels.com; hch@infradead.org; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> martin.petersen@oracle.com; hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> On Sat, Mar 12, 2016 at 01:52:48PM -0800, K. Y. Srinivasan wrote:
> > The default user scan function associated with FC (fc_user_scan)
> > is not suitable for FC hosts on Hyper-V since we don't have
> > an rport associated with FC host on Hyper-V . Set it to NULL so we can
> > support manual scan of FC targets on Hyper-V.
> 
> This isn't really how the FC transport class in intended to work, but
> neither is the eh_timed_out (which I haven't seen in my tree yet).
> 
> It sounds like storvsc simply shouldn't attach to the FC transport
> if it doesn't actually look like a FC HBA.

Till recently I had not. However, we do support publishing wwn in the guest and
some customers wanted this. That is the reason I am attaching FC transport and working
through the issues. With this change, I now have wwn names published in the guest and I can
also issue manual scan.


Regards,

K. Y 

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[Martin K. Petersen]

>>>>> "KY" == KY Srinivasan <kys@microsoft.com> writes:

KY> Till recently I had not. However, we do support publishing wwn in
KY> the guest and some customers wanted this. That is the reason I am
KY> attaching FC transport and working through the issues. With this
KY> change, I now have wwn names published in the guest and I can also
KY> issue manual scan.

Why does it have to look like FC? Will a device identification VPD page
not do the trick?

-- 
Martin K. Petersen	Oracle Linux Engineering

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: Martin K. Petersen [mailto:martin.petersen@oracle.com]
> Sent: Tuesday, March 15, 2016 2:25 PM
> To: KY Srinivasan <kys@microsoft.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> martin.petersen@oracle.com; hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> >>>>> "KY" == KY Srinivasan <kys@microsoft.com> writes:
> 
> KY> Till recently I had not. However, we do support publishing wwn in
> KY> the guest and some customers wanted this. That is the reason I am
> KY> attaching FC transport and working through the issues. With this
> KY> change, I now have wwn names published in the guest and I can also
> KY> issue manual scan.
> 
> Why does it have to look like FC? Will a device identification VPD page
> not do the trick?

How would I get the sysfs files under fc_host if I don't use the FC transport.
The customer scripts expect these sysfs files.

Regards,

K. Y
> 
> --
> Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[Martin K. Petersen]

>>>>> "KY" == KY Srinivasan <kys@microsoft.com> writes:

KY> How would I get the sysfs files under fc_host if I don't use the FC
KY> transport.  The customer scripts expect these sysfs files.

Right, but I was interested in finding out why they need those
files. And whether an alternative to the FC transport would be a better
solution.

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[James Bottomley]

On Wed, 2016-03-16 at 18:34 -0400, Martin K. Petersen wrote:
> > > > > > "KY" == KY Srinivasan <kys@microsoft.com> writes:
> 
> KY> How would I get the sysfs files under fc_host if I don't use the
> FC
> KY> transport.  The customer scripts expect these sysfs files.
> 
> Right, but I was interested in finding out why they need those
> files. And whether an alternative to the FC transport would be a 
> better solution.

If it's just the wwn file (or a set of other values), we might be able
to separate that bit out of the FC transport class so you can use it
independently ... do you have a full list of the files being used?

Thanks,

James

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com]
> Sent: Wednesday, March 16, 2016 4:08 PM
> To: Martin K. Petersen <martin.petersen@oracle.com>; KY Srinivasan
> <kys@microsoft.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> On Wed, 2016-03-16 at 18:34 -0400, Martin K. Petersen wrote:
> > > > > > > "KY" == KY Srinivasan <kys@microsoft.com> writes:
> >
> > KY> How would I get the sysfs files under fc_host if I don't use the
> > FC
> > KY> transport.  The customer scripts expect these sysfs files.
> >
> > Right, but I was interested in finding out why they need those
> > files. And whether an alternative to the FC transport would be a
> > better solution.
> 
> If it's just the wwn file (or a set of other values), we might be able
> to separate that bit out of the FC transport class so you can use it
> independently ... do you have a full list of the files being used?

Wwn files are what we can support on Hyper-V and that is what I want to support
(to address customer requirements).

Regards,

K. Y 

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[James Bottomley]

On Wed, 2016-03-16 at 23:15 +0000, KY Srinivasan wrote:
> 
> > -----Original Message-----
> > From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com
> > ]
> > Sent: Wednesday, March 16, 2016 4:08 PM
> > To: Martin K. Petersen <martin.petersen@oracle.com>; KY Srinivasan
> > <kys@microsoft.com>
> > Cc: Christoph Hellwig <hch@infradead.org>; 
> > gregkh@linuxfoundation.org;
> > linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> > ohering@suse.com; jbottomley@parallels.com; 
> > linux-scsi@vger.kernel.org;
> > apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> > hare@suse.de
> > Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC
> > hosts on
> > Hyper-V
> > 
> > On Wed, 2016-03-16 at 18:34 -0400, Martin K. Petersen wrote:
> > > > > > > > "KY" == KY Srinivasan <kys@microsoft.com> writes:
> > > 
> > > KY> How would I get the sysfs files under fc_host if I don't use
> > > the
> > > FC
> > > KY> transport.  The customer scripts expect these sysfs files.
> > > 
> > > Right, but I was interested in finding out why they need those
> > > files. And whether an alternative to the FC transport would be a
> > > better solution.
> > 
> > If it's just the wwn file (or a set of other values), we might be
> > able
> > to separate that bit out of the FC transport class so you can use
> > it
> > independently ... do you have a full list of the files being used?
> 
> Wwn files are what we can support on Hyper-V and that is what I want 
> to support (to address customer requirements).

There is no wwn file.  These are all the possible attributes they could
use; which one(s) do you want:

	/*
	 * Setup SCSI Host Attributes.
	 */
	SETUP_HOST_ATTRIBUTE_RD(node_name);
	SETUP_HOST_ATTRIBUTE_RD(port_name);
	SETUP_HOST_ATTRIBUTE_RD(permanent_port_name);
	SETUP_HOST_ATTRIBUTE_RD(supported_classes);
	SETUP_HOST_ATTRIBUTE_RD(supported_fc4s);
	SETUP_HOST_ATTRIBUTE_RD(supported_speeds);
	SETUP_HOST_ATTRIBUTE_RD(maxframe_size);
	if (ft->vport_create) {
		SETUP_HOST_ATTRIBUTE_RD_NS(max_npiv_vports);
		SETUP_HOST_ATTRIBUTE_RD_NS(npiv_vports_inuse);
	}
	SETUP_HOST_ATTRIBUTE_RD(serial_number);
	SETUP_HOST_ATTRIBUTE_RD(manufacturer);
	SETUP_HOST_ATTRIBUTE_RD(model);
	SETUP_HOST_ATTRIBUTE_RD(model_description);
	SETUP_HOST_ATTRIBUTE_RD(hardware_version);
	SETUP_HOST_ATTRIBUTE_RD(driver_version);
	SETUP_HOST_ATTRIBUTE_RD(firmware_version);
	SETUP_HOST_ATTRIBUTE_RD(optionrom_version);

	SETUP_HOST_ATTRIBUTE_RD(port_id);
	SETUP_HOST_ATTRIBUTE_RD(port_type);
	SETUP_HOST_ATTRIBUTE_RD(port_state);
	SETUP_HOST_ATTRIBUTE_RD(active_fc4s);
	SETUP_HOST_ATTRIBUTE_RD(speed);
	SETUP_HOST_ATTRIBUTE_RD(fabric_name);
	SETUP_HOST_ATTRIBUTE_RD(symbolic_name);
	SETUP_HOST_ATTRIBUTE_RW(system_hostname);

	/* Transport-managed attributes */
	SETUP_PRIVATE_HOST_ATTRIBUTE_RW(dev_loss_tmo);
	SETUP_PRIVATE_HOST_ATTRIBUTE_RW(tgtid_bind_type);
	if (ft->issue_fc_host_lip)
		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(issue_lip);
	if (ft->vport_create)
		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(vport_create);
	if (ft->vport_delete)
		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(vport_delete);
	/*
	 * Setup Remote Port Attributes.
	 */
	count=0;
	SETUP_RPORT_ATTRIBUTE_RD(maxframe_size);
	SETUP_RPORT_ATTRIBUTE_RD(supported_classes);
	SETUP_RPORT_ATTRIBUTE_RW(dev_loss_tmo);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(node_name);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_name);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_id);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(roles);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_state);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(scsi_target_id);
	SETUP_PRIVATE_RPORT_ATTRIBUTE_RW(fast_io_fail_tmo);

	/*
	 * Setup Virtual Port Attributes.
	 */
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_state);
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_last_state);
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(node_name);
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(port_name);
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(roles);
	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_type);
	SETUP_VPORT_ATTRIBUTE_RW(symbolic_name);
	SETUP_VPORT_ATTRIBUTE_WR(vport_delete);
	SETUP_VPORT_ATTRIBUTE_WR(vport_disable);

I'm assuming it's host and rport port_id?

James

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com]
> Sent: Wednesday, March 16, 2016 4:41 PM
> To: KY Srinivasan <kys@microsoft.com>; Martin K. Petersen
> <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> On Wed, 2016-03-16 at 23:15 +0000, KY Srinivasan wrote:
> >
> > > -----Original Message-----
> > > From: James Bottomley
> [mailto:James.Bottomley@HansenPartnership.com
> > > ]
> > > Sent: Wednesday, March 16, 2016 4:08 PM
> > > To: Martin K. Petersen <martin.petersen@oracle.com>; KY Srinivasan
> > > <kys@microsoft.com>
> > > Cc: Christoph Hellwig <hch@infradead.org>;
> > > gregkh@linuxfoundation.org;
> > > linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> > > ohering@suse.com; jbottomley@parallels.com;
> > > linux-scsi@vger.kernel.org;
> > > apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> > > hare@suse.de
> > > Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC
> > > hosts on
> > > Hyper-V
> > >
> > > On Wed, 2016-03-16 at 18:34 -0400, Martin K. Petersen wrote:
> > > > > > > > > "KY" == KY Srinivasan <kys@microsoft.com> writes:
> > > >
> > > > KY> How would I get the sysfs files under fc_host if I don't use
> > > > the
> > > > FC
> > > > KY> transport.  The customer scripts expect these sysfs files.
> > > >
> > > > Right, but I was interested in finding out why they need those
> > > > files. And whether an alternative to the FC transport would be a
> > > > better solution.
> > >
> > > If it's just the wwn file (or a set of other values), we might be
> > > able
> > > to separate that bit out of the FC transport class so you can use
> > > it
> > > independently ... do you have a full list of the files being used?
> >
> > Wwn files are what we can support on Hyper-V and that is what I want
> > to support (to address customer requirements).
> 
> There is no wwn file.  These are all the possible attributes they could
> use; which one(s) do you want:
> 
> 	/*
> 	 * Setup SCSI Host Attributes.
> 	 */
> 	SETUP_HOST_ATTRIBUTE_RD(node_name);
> 	SETUP_HOST_ATTRIBUTE_RD(port_name);
> 	SETUP_HOST_ATTRIBUTE_RD(permanent_port_name);
> 	SETUP_HOST_ATTRIBUTE_RD(supported_classes);
> 	SETUP_HOST_ATTRIBUTE_RD(supported_fc4s);
> 	SETUP_HOST_ATTRIBUTE_RD(supported_speeds);
> 	SETUP_HOST_ATTRIBUTE_RD(maxframe_size);
> 	if (ft->vport_create) {
> 		SETUP_HOST_ATTRIBUTE_RD_NS(max_npiv_vports);
> 		SETUP_HOST_ATTRIBUTE_RD_NS(npiv_vports_inuse);
> 	}
> 	SETUP_HOST_ATTRIBUTE_RD(serial_number);
> 	SETUP_HOST_ATTRIBUTE_RD(manufacturer);
> 	SETUP_HOST_ATTRIBUTE_RD(model);
> 	SETUP_HOST_ATTRIBUTE_RD(model_description);
> 	SETUP_HOST_ATTRIBUTE_RD(hardware_version);
> 	SETUP_HOST_ATTRIBUTE_RD(driver_version);
> 	SETUP_HOST_ATTRIBUTE_RD(firmware_version);
> 	SETUP_HOST_ATTRIBUTE_RD(optionrom_version);
> 
> 	SETUP_HOST_ATTRIBUTE_RD(port_id);
> 	SETUP_HOST_ATTRIBUTE_RD(port_type);
> 	SETUP_HOST_ATTRIBUTE_RD(port_state);
> 	SETUP_HOST_ATTRIBUTE_RD(active_fc4s);
> 	SETUP_HOST_ATTRIBUTE_RD(speed);
> 	SETUP_HOST_ATTRIBUTE_RD(fabric_name);
> 	SETUP_HOST_ATTRIBUTE_RD(symbolic_name);
> 	SETUP_HOST_ATTRIBUTE_RW(system_hostname);
> 
> 	/* Transport-managed attributes */
> 	SETUP_PRIVATE_HOST_ATTRIBUTE_RW(dev_loss_tmo);
> 	SETUP_PRIVATE_HOST_ATTRIBUTE_RW(tgtid_bind_type);
> 	if (ft->issue_fc_host_lip)
> 		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(issue_lip);
> 	if (ft->vport_create)
> 		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(vport_create);
> 	if (ft->vport_delete)
> 		SETUP_PRIVATE_HOST_ATTRIBUTE_RW(vport_delete);
> 	/*
> 	 * Setup Remote Port Attributes.
> 	 */
> 	count=0;
> 	SETUP_RPORT_ATTRIBUTE_RD(maxframe_size);
> 	SETUP_RPORT_ATTRIBUTE_RD(supported_classes);
> 	SETUP_RPORT_ATTRIBUTE_RW(dev_loss_tmo);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(node_name);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_name);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_id);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(roles);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(port_state);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(scsi_target_id);
> 	SETUP_PRIVATE_RPORT_ATTRIBUTE_RW(fast_io_fail_tmo);
> 
> 	/*
> 	 * Setup Virtual Port Attributes.
> 	 */
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_state);
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_last_state);
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(node_name);
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(port_name);
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(roles);
> 	SETUP_PRIVATE_VPORT_ATTRIBUTE_RD(vport_type);
> 	SETUP_VPORT_ATTRIBUTE_RW(symbolic_name);
> 	SETUP_VPORT_ATTRIBUTE_WR(vport_delete);
> 	SETUP_VPORT_ATTRIBUTE_WR(vport_disable);
> 
> I'm assuming it's host and rport port_id?

The only attributes I would be interested are:
1) node name
2) port name

Ideally, if this can show under /sys/class/fc_host/hostx/port_name and node_name,
it will be ideal since all user scripts can work.

Regards,

K. Y 

Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[James Bottomley]

On Thu, 2016-03-17 at 00:01 +0000, KY Srinivasan wrote:
> The only attributes I would be interested are:
> 1) node name
> 2) port name
> 
> Ideally, if this can show under /sys/class/fc_host/hostx/port_name
> and node_name,
> it will be ideal since all user scripts can work.

OK, like this?

>From 7af7c428e7e04ddcc87fda12d6571e3dff8ae024 Mon Sep 17 00:00:00 2001
From: James Bottomley <James.Bottomley@HansenPartnership.com>
Date: Fri, 18 Mar 2016 15:35:45 -0700
Subject: scsi_transport_fc: introduce lightweight class for virtualization
 systems

The FC transport class is very heavily tilted towards helping things
which operate a fabric (as it should be).  However, there seems to be
a need for a lightweight version for use in virtual systems that
simply want to show pass through FC information without making any use
of the heavyweight functions.  This is an attempt to give them what
they want: the lightweight class has no vports or rports and only two
host attributes.  Essentially, it's designed for the HV storvsc
driver, but if other virtualizataion systems have similar problems, we
can add more attributes.

Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
---
 drivers/scsi/scsi_transport_fc.c | 94 ++++++++++++++++++++++++++++++++++++++++
 include/scsi/scsi_transport_fc.h |  3 ++
 2 files changed, 97 insertions(+)

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 8a88226..a9fcb4d 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -351,6 +351,27 @@ struct fc_internal {
 
 #define to_fc_internal(tmpl)	container_of(tmpl, struct fc_internal, t)
 
+#define FC_LW_HOST_NUM_ATTRS 	2
+struct fc_lw_internal {
+	struct scsi_transport_template t;
+	struct fc_function_template *f;
+
+	/*
+	 * For attributes : each object has :
+	 *   An array of the actual attributes structures
+	 *   An array of null-terminated pointers to the attribute
+	 *     structures - used for mid-layer interaction.
+	 *
+	 * The attribute containers for the starget and host are are
+	 * part of the midlayer. As the remote port is specific to the
+	 * fc transport, we must provide the attribute container.
+	 */
+	struct device_attribute private_host_attrs[FC_LW_HOST_NUM_ATTRS];
+	struct device_attribute *host_attrs[FC_LW_HOST_NUM_ATTRS + 1];
+};
+
+#define to_fc_lw_internal(tmpl)	container_of(tmpl, struct fc_lw_internal, t)
+
 static int fc_target_setup(struct transport_container *tc, struct device *dev,
 			   struct device *cdev)
 {
@@ -472,6 +493,12 @@ static int fc_host_remove(struct transport_container *tc, struct device *dev,
 	return 0;
 }
 
+static DECLARE_TRANSPORT_CLASS(fc_lw_host_class,
+			       "fc_host",
+			       NULL,
+			       NULL,
+			       NULL);
+
 static DECLARE_TRANSPORT_CLASS(fc_host_class,
 			       "fc_host",
 			       fc_host_setup,
@@ -1968,6 +1995,25 @@ static int fc_host_match(struct attribute_container *cont,
 	return &i->t.host_attrs.ac == cont;
 }
 
+static int fc_lw_host_match(struct attribute_container *cont,
+			  struct device *dev)
+{
+	struct Scsi_Host *shost;
+	struct fc_lw_internal *i;
+
+	if (!scsi_is_host_device(dev))
+		return 0;
+
+	shost = dev_to_shost(dev);
+	if (!shost->transportt  || shost->transportt->host_attrs.ac.class
+	    != &fc_lw_host_class.class)
+		return 0;
+
+	i = to_fc_lw_internal(shost->transportt);
+
+	return &i->t.host_attrs.ac == cont;
+}
+
 static int fc_target_match(struct attribute_container *cont,
 			    struct device *dev)
 {
@@ -2171,6 +2217,54 @@ static int fc_it_nexus_response(struct Scsi_Host *shost, u64 nexus, int result)
 	return i->f->it_nexus_response(shost, nexus, result);
 }
 
+/**
+ * fc_attach_lw_transport - light weight attach function
+ * @ft:		function template for optional attributes
+ *
+ * This attach function is to be used only for virtual FC emulators
+ * which do not have a physical fabric underneath them and thus only
+ * need a few attributes and no helper functions
+ */
+struct scsi_transport_template *
+fc_lw_attach_transport(struct fc_function_template *ft)
+{
+	int count;
+	struct fc_lw_internal *i = kzalloc(sizeof(struct fc_lw_internal),
+					   GFP_KERNEL);
+
+	if (unlikely(!i))
+		return NULL;
+
+	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
+	i->t.host_attrs.ac.class = &fc_lw_host_class.class;
+	i->t.host_attrs.ac.match = fc_lw_host_match;
+	i->t.host_size = sizeof(struct fc_host_attrs);
+	transport_container_register(&i->t.host_attrs);
+
+	i->f = ft;
+
+	count = 0;
+	SETUP_HOST_ATTRIBUTE_RD(node_name);
+	SETUP_HOST_ATTRIBUTE_RD(port_name);
+
+	BUG_ON(count > FC_HOST_NUM_ATTRS);
+
+	i->host_attrs[count] = NULL;
+
+	return &i->t;
+}
+EXPORT_SYMBOL(fc_lw_attach_transport);
+
+void fc_lw_release_transport(struct scsi_transport_template *t)
+{
+	struct fc_lw_internal *i = to_fc_lw_internal(t);
+
+	transport_container_unregister(&i->t.host_attrs);
+
+	kfree(i);
+}
+EXPORT_SYMBOL(fc_lw_release_transport);
+
 struct scsi_transport_template *
 fc_attach_transport(struct fc_function_template *ft)
 {
diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
index 784bc2c..b0a9a64 100644
--- a/include/scsi/scsi_transport_fc.h
+++ b/include/scsi/scsi_transport_fc.h
@@ -835,6 +835,9 @@ fc_vport_set_state(struct fc_vport *vport, enum fc_vport_state new_state)
 	vport->vport_state = new_state;
 }
 
+struct scsi_transport_template *fc_lw_attach_transport(
+			struct fc_function_template *);
+void fc_lw_release_transport(struct scsi_transport_template *);
 struct scsi_transport_template *fc_attach_transport(
 			struct fc_function_template *);
 void fc_release_transport(struct scsi_transport_template *);
-- 
2.6.2

[PATCH 2/2] storvsc_drv: make use of the lightweight FC transport class

[James Bottomley]

Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
---
 drivers/scsi/storvsc_drv.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 3ddcabb..dcb7393 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1769,21 +1769,16 @@ static int __init storvsc_drv_init(void)
 		sizeof(u64)));
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
-	fc_transport_template = fc_attach_transport(&fc_transport_functions);
+	fc_transport_template = fc_lw_attach_transport(&fc_transport_functions);
 	if (!fc_transport_template)
 		return -ENODEV;
-
-	/*
-	 * Install Hyper-V specific timeout handler.
-	 */
-	fc_transport_template->eh_timed_out = storvsc_eh_timed_out;
 #endif
 
 	ret = vmbus_driver_register(&storvsc_drv);
 
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
 	if (ret)
-		fc_release_transport(fc_transport_template);
+		fc_lw_release_transport(fc_transport_template);
 #endif
 
 	return ret;
@@ -1793,7 +1788,7 @@ static void __exit storvsc_drv_exit(void)
 {
 	vmbus_driver_unregister(&storvsc_drv);
 #if IS_ENABLED(CONFIG_SCSI_FC_ATTRS)
-	fc_release_transport(fc_transport_template);
+	fc_lw_release_transport(fc_transport_template);
 #endif
 }
 
-- 
2.6.2

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com]
> Sent: Friday, March 18, 2016 3:41 PM
> To: KY Srinivasan <kys@microsoft.com>; Martin K. Petersen
> <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> On Thu, 2016-03-17 at 00:01 +0000, KY Srinivasan wrote:
> > The only attributes I would be interested are:
> > 1) node name
> > 2) port name
> >
> > Ideally, if this can show under /sys/class/fc_host/hostx/port_name
> > and node_name,
> > it will be ideal since all user scripts can work.
> 
> OK, like this?

Yes; thank you very much James. Looking at the patch though, it may be an 
overkill considering how much of the code is duplicated. The current fc transport
class does give us the flexibility to control the attributes we want to surface
(fc_function_template). In any case I will test this code and get back to you soon.

Regards,

K. Y

 
> 
> From 7af7c428e7e04ddcc87fda12d6571e3dff8ae024 Mon Sep 17 00:00:00
> 2001
> From: James Bottomley <James.Bottomley@HansenPartnership.com>
> Date: Fri, 18 Mar 2016 15:35:45 -0700
> Subject: scsi_transport_fc: introduce lightweight class for virtualization
>  systems
> 
> The FC transport class is very heavily tilted towards helping things
> which operate a fabric (as it should be).  However, there seems to be
> a need for a lightweight version for use in virtual systems that
> simply want to show pass through FC information without making any use
> of the heavyweight functions.  This is an attempt to give them what
> they want: the lightweight class has no vports or rports and only two
> host attributes.  Essentially, it's designed for the HV storvsc
> driver, but if other virtualizataion systems have similar problems, we
> can add more attributes.
> 
> Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
> ---
>  drivers/scsi/scsi_transport_fc.c | 94
> ++++++++++++++++++++++++++++++++++++++++
>  include/scsi/scsi_transport_fc.h |  3 ++
>  2 files changed, 97 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> index 8a88226..a9fcb4d 100644
> --- a/drivers/scsi/scsi_transport_fc.c
> +++ b/drivers/scsi/scsi_transport_fc.c
> @@ -351,6 +351,27 @@ struct fc_internal {
> 
>  #define to_fc_internal(tmpl)	container_of(tmpl, struct fc_internal, t)
> 
> +#define FC_LW_HOST_NUM_ATTRS 	2
> +struct fc_lw_internal {
> +	struct scsi_transport_template t;
> +	struct fc_function_template *f;
> +
> +	/*
> +	 * For attributes : each object has :
> +	 *   An array of the actual attributes structures
> +	 *   An array of null-terminated pointers to the attribute
> +	 *     structures - used for mid-layer interaction.
> +	 *
> +	 * The attribute containers for the starget and host are are
> +	 * part of the midlayer. As the remote port is specific to the
> +	 * fc transport, we must provide the attribute container.
> +	 */
> +	struct device_attribute
> private_host_attrs[FC_LW_HOST_NUM_ATTRS];
> +	struct device_attribute *host_attrs[FC_LW_HOST_NUM_ATTRS + 1];
> +};
> +
> +#define to_fc_lw_internal(tmpl)	container_of(tmpl, struct
> fc_lw_internal, t)
> +
>  static int fc_target_setup(struct transport_container *tc, struct device *dev,
>  			   struct device *cdev)
>  {
> @@ -472,6 +493,12 @@ static int fc_host_remove(struct transport_container
> *tc, struct device *dev,
>  	return 0;
>  }
> 
> +static DECLARE_TRANSPORT_CLASS(fc_lw_host_class,
> +			       "fc_host",
> +			       NULL,
> +			       NULL,
> +			       NULL);
> +
>  static DECLARE_TRANSPORT_CLASS(fc_host_class,
>  			       "fc_host",
>  			       fc_host_setup,
> @@ -1968,6 +1995,25 @@ static int fc_host_match(struct
> attribute_container *cont,
>  	return &i->t.host_attrs.ac == cont;
>  }
> 
> +static int fc_lw_host_match(struct attribute_container *cont,
> +			  struct device *dev)
> +{
> +	struct Scsi_Host *shost;
> +	struct fc_lw_internal *i;
> +
> +	if (!scsi_is_host_device(dev))
> +		return 0;
> +
> +	shost = dev_to_shost(dev);
> +	if (!shost->transportt  || shost->transportt->host_attrs.ac.class
> +	    != &fc_lw_host_class.class)
> +		return 0;
> +
> +	i = to_fc_lw_internal(shost->transportt);
> +
> +	return &i->t.host_attrs.ac == cont;
> +}
> +
>  static int fc_target_match(struct attribute_container *cont,
>  			    struct device *dev)
>  {
> @@ -2171,6 +2217,54 @@ static int fc_it_nexus_response(struct Scsi_Host
> *shost, u64 nexus, int result)
>  	return i->f->it_nexus_response(shost, nexus, result);
>  }
> 
> +/**
> + * fc_attach_lw_transport - light weight attach function
> + * @ft:		function template for optional attributes
> + *
> + * This attach function is to be used only for virtual FC emulators
> + * which do not have a physical fabric underneath them and thus only
> + * need a few attributes and no helper functions
> + */
> +struct scsi_transport_template *
> +fc_lw_attach_transport(struct fc_function_template *ft)
> +{
> +	int count;
> +	struct fc_lw_internal *i = kzalloc(sizeof(struct fc_lw_internal),
> +					   GFP_KERNEL);
> +
> +	if (unlikely(!i))
> +		return NULL;
> +
> +	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
> +	i->t.host_attrs.ac.class = &fc_lw_host_class.class;
> +	i->t.host_attrs.ac.match = fc_lw_host_match;
> +	i->t.host_size = sizeof(struct fc_host_attrs);
> +	transport_container_register(&i->t.host_attrs);
> +
> +	i->f = ft;
> +
> +	count = 0;
> +	SETUP_HOST_ATTRIBUTE_RD(node_name);
> +	SETUP_HOST_ATTRIBUTE_RD(port_name);
> +
> +	BUG_ON(count > FC_HOST_NUM_ATTRS);
> +
> +	i->host_attrs[count] = NULL;
> +
> +	return &i->t;
> +}
> +EXPORT_SYMBOL(fc_lw_attach_transport);
> +
> +void fc_lw_release_transport(struct scsi_transport_template *t)
> +{
> +	struct fc_lw_internal *i = to_fc_lw_internal(t);
> +
> +	transport_container_unregister(&i->t.host_attrs);
> +
> +	kfree(i);
> +}
> +EXPORT_SYMBOL(fc_lw_release_transport);
> +
>  struct scsi_transport_template *
>  fc_attach_transport(struct fc_function_template *ft)
>  {
> diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
> index 784bc2c..b0a9a64 100644
> --- a/include/scsi/scsi_transport_fc.h
> +++ b/include/scsi/scsi_transport_fc.h
> @@ -835,6 +835,9 @@ fc_vport_set_state(struct fc_vport *vport, enum
> fc_vport_state new_state)
>  	vport->vport_state = new_state;
>  }
> 
> +struct scsi_transport_template *fc_lw_attach_transport(
> +			struct fc_function_template *);
> +void fc_lw_release_transport(struct scsi_transport_template *);
>  struct scsi_transport_template *fc_attach_transport(
>  			struct fc_function_template *);
>  void fc_release_transport(struct scsi_transport_template *);
> --
> 2.6.2

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: KY Srinivasan
> Sent: Sunday, March 20, 2016 11:59 AM
> To: 'James Bottomley' <James.Bottomley@HansenPartnership.com>; Martin
> K. Petersen <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> hare@suse.de
> Subject: RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> 
> 
> > -----Original Message-----
> > From: James Bottomley
> [mailto:James.Bottomley@HansenPartnership.com]
> > Sent: Friday, March 18, 2016 3:41 PM
> > To: KY Srinivasan <kys@microsoft.com>; Martin K. Petersen
> > <martin.petersen@oracle.com>
> > Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> > linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> > ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> > apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> > hare@suse.de
> > Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> > Hyper-V
> >
> > On Thu, 2016-03-17 at 00:01 +0000, KY Srinivasan wrote:
> > > The only attributes I would be interested are:
> > > 1) node name
> > > 2) port name
> > >
> > > Ideally, if this can show under /sys/class/fc_host/hostx/port_name
> > > and node_name,
> > > it will be ideal since all user scripts can work.
> >
> > OK, like this?
> 
> Yes; thank you very much James. Looking at the patch though, it may be an
> overkill considering how much of the code is duplicated. The current fc
> transport
> class does give us the flexibility to control the attributes we want to surface
> (fc_function_template). In any case I will test this code and get back to you
> soon.

Today I got a chance to test this patch. Looks like all the state is not getting
properly set in this new transport class. I am hitting this NULL pointer reference fault in
get_device_parent(). Looks like the device class is not properly setup for
this transport class. class_dir_create_and_add() is not called for this class
and so the glue_dirs is NULL.   I fixed the issue:

1) You will need to call the transport_class_register() for this new transport class in
fc_transport_init()
2) We cannot use fc_host as the name in this new class since the standard fc transport already
Uses that name. I changed the name to get this to work. This will create a new directory under /sys/class.
So my original goal of  being compatible with existing scripts that expect to find the information under
/sys/class/fc_host will not be met.

Regards,

K. Y


> 
> Regards,
> 
> K. Y
> 
> 
> >
> > From 7af7c428e7e04ddcc87fda12d6571e3dff8ae024 Mon Sep 17 00:00:00
> > 2001
> > From: James Bottomley <James.Bottomley@HansenPartnership.com>
> > Date: Fri, 18 Mar 2016 15:35:45 -0700
> > Subject: scsi_transport_fc: introduce lightweight class for virtualization
> >  systems
> >
> > The FC transport class is very heavily tilted towards helping things
> > which operate a fabric (as it should be).  However, there seems to be
> > a need for a lightweight version for use in virtual systems that
> > simply want to show pass through FC information without making any use
> > of the heavyweight functions.  This is an attempt to give them what
> > they want: the lightweight class has no vports or rports and only two
> > host attributes.  Essentially, it's designed for the HV storvsc
> > driver, but if other virtualizataion systems have similar problems, we
> > can add more attributes.
> >
> > Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
> > ---
> >  drivers/scsi/scsi_transport_fc.c | 94
> > ++++++++++++++++++++++++++++++++++++++++
> >  include/scsi/scsi_transport_fc.h |  3 ++
> >  2 files changed, 97 insertions(+)
> >
> > diff --git a/drivers/scsi/scsi_transport_fc.c
> b/drivers/scsi/scsi_transport_fc.c
> > index 8a88226..a9fcb4d 100644
> > --- a/drivers/scsi/scsi_transport_fc.c
> > +++ b/drivers/scsi/scsi_transport_fc.c
> > @@ -351,6 +351,27 @@ struct fc_internal {
> >
> >  #define to_fc_internal(tmpl)	container_of(tmpl, struct fc_internal, t)
> >
> > +#define FC_LW_HOST_NUM_ATTRS 	2
> > +struct fc_lw_internal {
> > +	struct scsi_transport_template t;
> > +	struct fc_function_template *f;
> > +
> > +	/*
> > +	 * For attributes : each object has :
> > +	 *   An array of the actual attributes structures
> > +	 *   An array of null-terminated pointers to the attribute
> > +	 *     structures - used for mid-layer interaction.
> > +	 *
> > +	 * The attribute containers for the starget and host are are
> > +	 * part of the midlayer. As the remote port is specific to the
> > +	 * fc transport, we must provide the attribute container.
> > +	 */
> > +	struct device_attribute
> > private_host_attrs[FC_LW_HOST_NUM_ATTRS];
> > +	struct device_attribute *host_attrs[FC_LW_HOST_NUM_ATTRS + 1];
> > +};
> > +
> > +#define to_fc_lw_internal(tmpl)	container_of(tmpl, struct
> > fc_lw_internal, t)
> > +
> >  static int fc_target_setup(struct transport_container *tc, struct device
> *dev,
> >  			   struct device *cdev)
> >  {
> > @@ -472,6 +493,12 @@ static int fc_host_remove(struct
> transport_container
> > *tc, struct device *dev,
> >  	return 0;
> >  }
> >
> > +static DECLARE_TRANSPORT_CLASS(fc_lw_host_class,
> > +			       "fc_host",
> > +			       NULL,
> > +			       NULL,
> > +			       NULL);
> > +
> >  static DECLARE_TRANSPORT_CLASS(fc_host_class,
> >  			       "fc_host",
> >  			       fc_host_setup,
> > @@ -1968,6 +1995,25 @@ static int fc_host_match(struct
> > attribute_container *cont,
> >  	return &i->t.host_attrs.ac == cont;
> >  }
> >
> > +static int fc_lw_host_match(struct attribute_container *cont,
> > +			  struct device *dev)
> > +{
> > +	struct Scsi_Host *shost;
> > +	struct fc_lw_internal *i;
> > +
> > +	if (!scsi_is_host_device(dev))
> > +		return 0;
> > +
> > +	shost = dev_to_shost(dev);
> > +	if (!shost->transportt  || shost->transportt->host_attrs.ac.class
> > +	    != &fc_lw_host_class.class)
> > +		return 0;
> > +
> > +	i = to_fc_lw_internal(shost->transportt);
> > +
> > +	return &i->t.host_attrs.ac == cont;
> > +}
> > +
> >  static int fc_target_match(struct attribute_container *cont,
> >  			    struct device *dev)
> >  {
> > @@ -2171,6 +2217,54 @@ static int fc_it_nexus_response(struct Scsi_Host
> > *shost, u64 nexus, int result)
> >  	return i->f->it_nexus_response(shost, nexus, result);
> >  }
> >
> > +/**
> > + * fc_attach_lw_transport - light weight attach function
> > + * @ft:		function template for optional attributes
> > + *
> > + * This attach function is to be used only for virtual FC emulators
> > + * which do not have a physical fabric underneath them and thus only
> > + * need a few attributes and no helper functions
> > + */
> > +struct scsi_transport_template *
> > +fc_lw_attach_transport(struct fc_function_template *ft)
> > +{
> > +	int count;
> > +	struct fc_lw_internal *i = kzalloc(sizeof(struct fc_lw_internal),
> > +					   GFP_KERNEL);
> > +
> > +	if (unlikely(!i))
> > +		return NULL;
> > +
> > +	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
> > +	i->t.host_attrs.ac.class = &fc_lw_host_class.class;
> > +	i->t.host_attrs.ac.match = fc_lw_host_match;
> > +	i->t.host_size = sizeof(struct fc_host_attrs);
> > +	transport_container_register(&i->t.host_attrs);
> > +
> > +	i->f = ft;
> > +
> > +	count = 0;
> > +	SETUP_HOST_ATTRIBUTE_RD(node_name);
> > +	SETUP_HOST_ATTRIBUTE_RD(port_name);
> > +
> > +	BUG_ON(count > FC_HOST_NUM_ATTRS);
> > +
> > +	i->host_attrs[count] = NULL;
> > +
> > +	return &i->t;
> > +}
> > +EXPORT_SYMBOL(fc_lw_attach_transport);
> > +
> > +void fc_lw_release_transport(struct scsi_transport_template *t)
> > +{
> > +	struct fc_lw_internal *i = to_fc_lw_internal(t);
> > +
> > +	transport_container_unregister(&i->t.host_attrs);
> > +
> > +	kfree(i);
> > +}
> > +EXPORT_SYMBOL(fc_lw_release_transport);
> > +
> >  struct scsi_transport_template *
> >  fc_attach_transport(struct fc_function_template *ft)
> >  {
> > diff --git a/include/scsi/scsi_transport_fc.h
> b/include/scsi/scsi_transport_fc.h
> > index 784bc2c..b0a9a64 100644
> > --- a/include/scsi/scsi_transport_fc.h
> > +++ b/include/scsi/scsi_transport_fc.h
> > @@ -835,6 +835,9 @@ fc_vport_set_state(struct fc_vport *vport, enum
> > fc_vport_state new_state)
> >  	vport->vport_state = new_state;
> >  }
> >
> > +struct scsi_transport_template *fc_lw_attach_transport(
> > +			struct fc_function_template *);
> > +void fc_lw_release_transport(struct scsi_transport_template *);
> >  struct scsi_transport_template *fc_attach_transport(
> >  			struct fc_function_template *);
> >  void fc_release_transport(struct scsi_transport_template *);
> > --
> > 2.6.2

RE: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V

[KY Srinivasan]

> -----Original Message-----
> From: James Bottomley [mailto:James.Bottomley@HansenPartnership.com]
> Sent: Friday, March 18, 2016 3:41 PM
> To: KY Srinivasan <kys@microsoft.com>; Martin K. Petersen
> <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@infradead.org>; gregkh@linuxfoundation.org;
> linux-kernel@vger.kernel.org; devel@linuxdriverproject.org;
> ohering@suse.com; jbottomley@parallels.com; linux-scsi@vger.kernel.org;
> apw@canonical.com; vkuznets@redhat.com; jasowang@redhat.com;
> hare@suse.de
> Subject: Re: [PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on
> Hyper-V
> 
> On Thu, 2016-03-17 at 00:01 +0000, KY Srinivasan wrote:
> > The only attributes I would be interested are:
> > 1) node name
> > 2) port name
> >
> > Ideally, if this can show under /sys/class/fc_host/hostx/port_name
> > and node_name,
> > it will be ideal since all user scripts can work.
> 
> OK, like this?
> 
> From 7af7c428e7e04ddcc87fda12d6571e3dff8ae024 Mon Sep 17 00:00:00
> 2001
> From: James Bottomley <James.Bottomley@HansenPartnership.com>
> Date: Fri, 18 Mar 2016 15:35:45 -0700
> Subject: scsi_transport_fc: introduce lightweight class for virtualization
>  systems
> 
> The FC transport class is very heavily tilted towards helping things
> which operate a fabric (as it should be).  However, there seems to be
> a need for a lightweight version for use in virtual systems that
> simply want to show pass through FC information without making any use
> of the heavyweight functions.  This is an attempt to give them what
> they want: the lightweight class has no vports or rports and only two
> host attributes.  Essentially, it's designed for the HV storvsc
> driver, but if other virtualizataion systems have similar problems, we
> can add more attributes.
> 
> Signed-off-by: James Bottomley <jejb@linux.vnet.ibm.com>
> ---
>  drivers/scsi/scsi_transport_fc.c | 94
> ++++++++++++++++++++++++++++++++++++++++
>  include/scsi/scsi_transport_fc.h |  3 ++
>  2 files changed, 97 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> index 8a88226..a9fcb4d 100644
> --- a/drivers/scsi/scsi_transport_fc.c
> +++ b/drivers/scsi/scsi_transport_fc.c
> @@ -351,6 +351,27 @@ struct fc_internal {
> 
>  #define to_fc_internal(tmpl)	container_of(tmpl, struct fc_internal, t)
> 
> +#define FC_LW_HOST_NUM_ATTRS 	2
> +struct fc_lw_internal {
> +	struct scsi_transport_template t;
> +	struct fc_function_template *f;
> +
> +	/*
> +	 * For attributes : each object has :
> +	 *   An array of the actual attributes structures
> +	 *   An array of null-terminated pointers to the attribute
> +	 *     structures - used for mid-layer interaction.
> +	 *
> +	 * The attribute containers for the starget and host are are
> +	 * part of the midlayer. As the remote port is specific to the
> +	 * fc transport, we must provide the attribute container.
> +	 */
> +	struct device_attribute
> private_host_attrs[FC_LW_HOST_NUM_ATTRS];
> +	struct device_attribute *host_attrs[FC_LW_HOST_NUM_ATTRS + 1];
> +};
> +
> +#define to_fc_lw_internal(tmpl)	container_of(tmpl, struct
> fc_lw_internal, t)
> +
>  static int fc_target_setup(struct transport_container *tc, struct device *dev,
>  			   struct device *cdev)
>  {
> @@ -472,6 +493,12 @@ static int fc_host_remove(struct transport_container
> *tc, struct device *dev,
>  	return 0;
>  }
> 
> +static DECLARE_TRANSPORT_CLASS(fc_lw_host_class,
> +			       "fc_host",
> +			       NULL,
> +			       NULL,
> +			       NULL);
> +
>  static DECLARE_TRANSPORT_CLASS(fc_host_class,
>  			       "fc_host",
>  			       fc_host_setup,
> @@ -1968,6 +1995,25 @@ static int fc_host_match(struct
> attribute_container *cont,
>  	return &i->t.host_attrs.ac == cont;
>  }
> 
> +static int fc_lw_host_match(struct attribute_container *cont,
> +			  struct device *dev)
> +{
> +	struct Scsi_Host *shost;
> +	struct fc_lw_internal *i;
> +
> +	if (!scsi_is_host_device(dev))
> +		return 0;
> +
> +	shost = dev_to_shost(dev);
> +	if (!shost->transportt  || shost->transportt->host_attrs.ac.class
> +	    != &fc_lw_host_class.class)
> +		return 0;
> +
> +	i = to_fc_lw_internal(shost->transportt);
> +
> +	return &i->t.host_attrs.ac == cont;
> +}
> +
>  static int fc_target_match(struct attribute_container *cont,
>  			    struct device *dev)
>  {
> @@ -2171,6 +2217,54 @@ static int fc_it_nexus_response(struct Scsi_Host
> *shost, u64 nexus, int result)
>  	return i->f->it_nexus_response(shost, nexus, result);
>  }
> 
> +/**
> + * fc_attach_lw_transport - light weight attach function
> + * @ft:		function template for optional attributes
> + *
> + * This attach function is to be used only for virtual FC emulators
> + * which do not have a physical fabric underneath them and thus only
> + * need a few attributes and no helper functions
> + */
> +struct scsi_transport_template *
> +fc_lw_attach_transport(struct fc_function_template *ft)
> +{
> +	int count;
> +	struct fc_lw_internal *i = kzalloc(sizeof(struct fc_lw_internal),
> +					   GFP_KERNEL);
> +
> +	if (unlikely(!i))
> +		return NULL;
> +
> +	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
> +	i->t.host_attrs.ac.class = &fc_lw_host_class.class;
> +	i->t.host_attrs.ac.match = fc_lw_host_match;
> +	i->t.host_size = sizeof(struct fc_host_attrs);
> +	transport_container_register(&i->t.host_attrs);
> +
> +	i->f = ft;
> +
> +	count = 0;
> +	SETUP_HOST_ATTRIBUTE_RD(node_name);
> +	SETUP_HOST_ATTRIBUTE_RD(port_name);
> +
> +	BUG_ON(count > FC_HOST_NUM_ATTRS);
> +
> +	i->host_attrs[count] = NULL;
> +
> +	return &i->t;
> +}
> +EXPORT_SYMBOL(fc_lw_attach_transport);
> +
> +void fc_lw_release_transport(struct scsi_transport_template *t)
> +{
> +	struct fc_lw_internal *i = to_fc_lw_internal(t);
> +
> +	transport_container_unregister(&i->t.host_attrs);
> +
> +	kfree(i);
> +}
> +EXPORT_SYMBOL(fc_lw_release_transport);
> +
>  struct scsi_transport_template *
>  fc_attach_transport(struct fc_function_template *ft)
>  {
> diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
> index 784bc2c..b0a9a64 100644
> --- a/include/scsi/scsi_transport_fc.h
> +++ b/include/scsi/scsi_transport_fc.h
> @@ -835,6 +835,9 @@ fc_vport_set_state(struct fc_vport *vport, enum
> fc_vport_state new_state)
>  	vport->vport_state = new_state;
>  }
> 
> +struct scsi_transport_template *fc_lw_attach_transport(
> +			struct fc_function_template *);
> +void fc_lw_release_transport(struct scsi_transport_template *);
>  struct scsi_transport_template *fc_attach_transport(
>  			struct fc_function_template *);
>  void fc_release_transport(struct scsi_transport_template *);
> --
> 2.6.2

James,

It was great talking to you this afternoon. Is this what you had in mind:

drivers/scsi/scsi_transport_fc.c |  133 ++++++++++++++++++++++++++++++++++++--
 include/scsi/scsi_transport_fc.h |    3 +
 2 files changed, 130 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 24eaaf6..b8cadd2 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -351,6 +351,27 @@ struct fc_internal {
 
 #define to_fc_internal(tmpl)	container_of(tmpl, struct fc_internal, t)
 
+#define FC_LW_HOST_NUM_ATTRS 	2
+struct fc_lw_internal {
+	struct scsi_transport_template t;
+	struct fc_function_template *f;
+
+	/*
+	 * For attributes : each object has :
+	 *   An array of the actual attributes structures
+	 *   An array of null-terminated pointers to the attribute
+	 *     structures - used for mid-layer interaction.
+	 *
+	 * The attribute containers for the starget and host are are
+	 * part of the midlayer. As the remote port is specific to the
+	 * fc transport, we must provide the attribute container.
+	 */
+	struct device_attribute private_host_attrs[FC_LW_HOST_NUM_ATTRS];
+	struct device_attribute *host_attrs[FC_LW_HOST_NUM_ATTRS + 1];
+};
+
+#define to_fc_lw_internal(tmpl)	container_of(tmpl, struct fc_lw_internal, t)
+
 static int fc_target_setup(struct transport_container *tc, struct device *dev,
 			   struct device *cdev)
 {
@@ -472,6 +493,12 @@ static int fc_host_remove(struct transport_container *tc, struct device *dev,
 	return 0;
 }
 
+static DECLARE_TRANSPORT_CLASS(fc_lw_host_class,
+			       "fc_host",
+			       NULL,
+			       NULL,
+			       NULL);
+
 static DECLARE_TRANSPORT_CLASS(fc_host_class,
 			       "fc_host",
 			       fc_host_setup,
@@ -654,11 +681,20 @@ send_vendor_fail:
 EXPORT_SYMBOL(fc_host_post_vendor_event);
 
 
+static bool transport_inited;
+static bool lw_transport_inited;
 
-static __init int fc_transport_init(void)
+static int fc_transport_init(bool lw_transport)
 {
 	int error;
+	bool inited = cmpxchg(&transport_inited, transport_inited, true);
 
+	/*
+	 * If transport has already been inited, just return.
+	 */
+	if (inited)
+		return 0;
+	
 	atomic_set(&fc_event_seq, 0);
 
 	error = transport_class_register(&fc_host_class);
@@ -670,9 +706,15 @@ static __init int fc_transport_init(void)
 	error = transport_class_register(&fc_rport_class);
 	if (error)
 		goto unreg_vport_class;
-	error = transport_class_register(&fc_transport_class);
+	if (lw_transport)
+		error = transport_class_register(&fc_lw_host_class);
+	else 
+		error = transport_class_register(&fc_transport_class);
 	if (error)
 		goto unreg_rport_class;
+
+	if (lw_transport)
+		 lw_transport_inited = true;
 	return 0;
 
 unreg_rport_class:
@@ -686,8 +728,12 @@ unreg_host_class:
 
 static void __exit fc_transport_exit(void)
 {
-	transport_class_unregister(&fc_transport_class);
+	if (lw_transport_inited)
+		transport_class_unregister(&fc_lw_host_class);
+	else
+		transport_class_unregister(&fc_transport_class);
 	transport_class_unregister(&fc_rport_class);
+	if (lw_transport_inited)
 	transport_class_unregister(&fc_host_class);
 	transport_class_unregister(&fc_vport_class);
 }
@@ -1968,6 +2014,25 @@ static int fc_host_match(struct attribute_container *cont,
 	return &i->t.host_attrs.ac == cont;
 }
 
+static int fc_lw_host_match(struct attribute_container *cont,
+			  struct device *dev)
+{
+	struct Scsi_Host *shost;
+	struct fc_lw_internal *i;
+
+	if (!scsi_is_host_device(dev))
+		return 0;
+
+	shost = dev_to_shost(dev);
+	if (!shost->transportt  || shost->transportt->host_attrs.ac.class
+	    != &fc_lw_host_class.class)
+		return 0;
+
+	i = to_fc_lw_internal(shost->transportt);
+
+	return &i->t.host_attrs.ac == cont;
+}
+
 static int fc_target_match(struct attribute_container *cont,
 			    struct device *dev)
 {
@@ -2171,13 +2236,70 @@ static int fc_it_nexus_response(struct Scsi_Host *shost, u64 nexus, int result)
 	return i->f->it_nexus_response(shost, nexus, result);
 }
 
+/**
+ * fc_attach_lw_transport - light weight attach function
+ * @ft:		function template for optional attributes
+ *
+ * This attach function is to be used only for virtual FC emulators
+ * which do not have a physical fabric underneath them and thus only
+ * need a few attributes and no helper functions
+ */
+struct scsi_transport_template *
+fc_lw_attach_transport(struct fc_function_template *ft)
+{
+	int count;
+	struct fc_lw_internal *i;
+
+	if (fc_transport_init(true))
+		return NULL;
+
+	i = kzalloc(sizeof(struct fc_lw_internal),
+		    GFP_KERNEL);
+
+	if (unlikely(!i))
+		return NULL;
+
+	i->t.host_attrs.ac.attrs = &i->host_attrs[0];
+	i->t.host_attrs.ac.class = &fc_lw_host_class.class;
+	i->t.host_attrs.ac.match = fc_lw_host_match;
+	i->t.host_size = sizeof(struct fc_host_attrs);
+	transport_container_register(&i->t.host_attrs);
+
+	i->f = ft;
+
+	count = 0;
+	SETUP_HOST_ATTRIBUTE_RD(node_name);
+	SETUP_HOST_ATTRIBUTE_RD(port_name);
+
+	BUG_ON(count > FC_HOST_NUM_ATTRS);
+
+	i->host_attrs[count] = NULL;
+
+	return &i->t;
+}
+EXPORT_SYMBOL(fc_lw_attach_transport);
+
+void fc_lw_release_transport(struct scsi_transport_template *t)
+{
+	struct fc_lw_internal *i = to_fc_lw_internal(t);
+
+	transport_container_unregister(&i->t.host_attrs);
+
+	kfree(i);
+}
+EXPORT_SYMBOL(fc_lw_release_transport);
+
 struct scsi_transport_template *
 fc_attach_transport(struct fc_function_template *ft)
 {
 	int count;
-	struct fc_internal *i = kzalloc(sizeof(struct fc_internal),
-					GFP_KERNEL);
+	struct fc_internal *i;
+
+	if (fc_transport_init(false))
+		return NULL;
 
+	i = kzalloc(sizeof(struct fc_internal),
+			   GFP_KERNEL);
 	if (unlikely(!i))
 		return NULL;
 
@@ -4148,5 +4270,4 @@ MODULE_AUTHOR("James Smart");
 MODULE_DESCRIPTION("FC Transport Attributes");
 MODULE_LICENSE("GPL");
 
-module_init(fc_transport_init);
 module_exit(fc_transport_exit);
diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
index 784bc2c..b0a9a64 100644
--- a/include/scsi/scsi_transport_fc.h
+++ b/include/scsi/scsi_transport_fc.h
@@ -835,6 +835,9 @@ fc_vport_set_state(struct fc_vport *vport, enum fc_vport_state new_state)
 	vport->vport_state = new_state;
 }
 
+struct scsi_transport_template *fc_lw_attach_transport(
+			struct fc_function_template *);
+void fc_lw_release_transport(struct scsi_transport_template *);
 struct scsi_transport_template *fc_attach_transport(
 			struct fc_function_template *);
 void fc_release_transport(struct scsi_transport_template *);
-- 
1.7.4.1