RE: [PATCH 1/2] scsi: scsi_transport_fc: Provide a lightweight option for Virtual FC Hosts.

[KY Srinivasan]

> -Original Message-
> From: Christoph Hellwig [mailto:h...@infradead.org]
> Sent: Thursday, January 19, 2017 7:12 AM
> To: Cathy Avery <cav...@redhat.com>
> Cc: KY Srinivasan <k...@microsoft.com>; Haiyang Zhang
> <haiya...@microsoft.com>; j...@linux.vnet.ibm.com;
> martin.peter...@oracle.com; de...@linuxdriverproject.org; linux-
> ker...@vger.kernel.org; linux-scsi@vger.kernel.org
> Subject: Re: [PATCH 1/2] scsi: scsi_transport_fc: Provide a lightweight option
> for Virtual FC Hosts.
> 
> On Wed, Jan 18, 2017 at 03:28:57PM -0500, Cathy Avery wrote:
> > The patch provides a means to offer a lightweight option to the
> > current FC transport class. The new option is selected by a
> > driver when it indicates it wants the lightweight
> > transport via fc_function_template.
> 
> This need some really good documentation in the code and changelog
> what "lightweight" means.  It's a pretty horrible term, btw.

This was a concept that James proposed almost a year ago. I agree, we need to 
document this
better.

K. Y

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Re: [PATCH 1/2] scsi: scsi_transport_fc: Provide a lightweight option for Virtual FC Hosts.

[Cathy Avery]

On 01/19/2017 10:11 AM, Christoph Hellwig wrote:

On Wed, Jan 18, 2017 at 03:28:57PM -0500, Cathy Avery wrote:

The patch provides a means to offer a lightweight option to the
current FC transport class. The new option is selected by a
driver when it indicates it wants the lightweight
transport via fc_function_template.

This need some really good documentation in the code and changelog
what "lightweight" means.  It's a pretty horrible term, btw.


Thanks, I will work on better documentation and a better name.

Cathy
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Re: [PATCH 1/2] scsi: scsi_transport_fc: Provide a lightweight option for Virtual FC Hosts.

[Christoph Hellwig]

On Wed, Jan 18, 2017 at 03:28:57PM -0500, Cathy Avery wrote:
> The patch provides a means to offer a lightweight option to the
> current FC transport class. The new option is selected by a
> driver when it indicates it wants the lightweight
> transport via fc_function_template.

This need some really good documentation in the code and changelog
what "lightweight" means.  It's a pretty horrible term, btw.
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[PATCH 1/2] scsi: scsi_transport_fc: Provide a lightweight option for Virtual FC Hosts.

[Cathy Avery]

The patch provides a means to offer a lightweight option to the
current FC transport class. The new option is selected by a
driver when it indicates it wants the lightweight
transport via fc_function_template.

Signed-off-by: Cathy Avery 
---
 drivers/scsi/scsi_transport_fc.c | 125 +--
 include/scsi/scsi_transport_fc.h |   1 +
 2 files changed, 122 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 03577bd..4adc669 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -50,6 +50,15 @@ static int fc_bsg_hostadd(struct Scsi_Host *, struct 
fc_host_attrs *);
 static int fc_bsg_rportadd(struct Scsi_Host *, struct fc_rport *);
 static void fc_bsg_remove(struct request_queue *);
 static void fc_bsg_goose_queue(struct fc_rport *);
+static int fc_host_lw_setup(struct Scsi_Host *, struct fc_host_attrs *);
+static int fc_host_hw_setup(struct Scsi_Host *, struct fc_host_attrs *);
+static int fc_host_hw_remove(struct fc_host_attrs *);
+static struct scsi_transport_template *
+   fc_attach_lw_transport(struct fc_function_template *);
+static struct scsi_transport_template *
+   fc_attach_hw_transport(struct fc_function_template *);
+static void fc_remove_lw_host(struct Scsi_Host *);
+static void fc_remove_hw_host(struct Scsi_Host *, struct fc_host_attrs *);
 
 /*
  * Module Parameters
@@ -352,6 +361,10 @@ struct fc_internal {
 
 #define to_fc_internal(tmpl)   container_of(tmpl, struct fc_internal, t)
 
+
+static void fc_release_lw_transport(struct fc_internal *);
+static void fc_release_hw_transport(struct fc_internal *);
+
 static int fc_target_setup(struct transport_container *tc, struct device *dev,
   struct device *cdev)
 {
@@ -387,7 +400,26 @@ static int fc_host_setup(struct transport_container *tc, 
struct device *dev,
 {
struct Scsi_Host *shost = dev_to_shost(dev);
struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+   struct fc_internal *i = to_fc_internal(shost->transportt);
+
+   if (i->f->lightweight_transport)
+   return fc_host_lw_setup(shost, fc_host);
+
+   return fc_host_hw_setup(shost, fc_host);
+}
+
+static int fc_host_lw_setup(struct Scsi_Host *shost,
+   struct fc_host_attrs *fc_host)
+{
+   fc_host->node_name = -1;
+   fc_host->port_name = -1;
+
+   return 0;
+}
 
+static int fc_host_hw_setup(struct Scsi_Host *shost,
+   struct fc_host_attrs *fc_host)
+{
/*
 * Set default values easily detected by the midlayer as
 * failure cases.  The scsi lldd is responsible for initializing
@@ -468,7 +500,16 @@ static int fc_host_remove(struct transport_container *tc, 
struct device *dev,
 {
struct Scsi_Host *shost = dev_to_shost(dev);
struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+   struct fc_internal *i = to_fc_internal(shost->transportt);
+
+   if (i->f->lightweight_transport)
+   return 0;
 
+   return fc_host_hw_remove(fc_host);
+}
+
+static int fc_host_hw_remove(struct fc_host_attrs *fc_host)
+{
fc_bsg_remove(fc_host->rqst_q);
return 0;
 }
@@ -2175,6 +2216,49 @@ static int fc_it_nexus_response(struct Scsi_Host *shost, 
u64 nexus, int result)
 struct scsi_transport_template *
 fc_attach_transport(struct fc_function_template *ft)
 {
+   if (ft->lightweight_transport)
+   return fc_attach_lw_transport(ft);
+
+   return fc_attach_hw_transport(ft);
+}
+EXPORT_SYMBOL(fc_attach_transport);
+
+
+struct scsi_transport_template *
+fc_attach_lw_transport(struct fc_function_template *ft)
+{
+   int count;
+   struct fc_internal *i;
+
+   i = kzalloc(sizeof(struct fc_internal),
+   GFP_KERNEL);
+
+   if (unlikely(!i))
+   return NULL;
+
+   i->t.host_attrs.ac.attrs = >host_attrs[0];
+   i->t.host_attrs.ac.class = _host_class.class;
+   i->t.host_attrs.ac.match = fc_host_match;
+   i->t.host_size = sizeof(struct fc_host_attrs);
+   transport_container_register(>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 >t;
+}
+
+
+struct scsi_transport_template *
+fc_attach_hw_transport(struct fc_function_template *ft)
+{
int count;
struct fc_internal *i = kzalloc(sizeof(struct fc_internal),
GFP_KERNEL);
@@ -2318,12 +2402,27 @@ fc_attach_transport(struct fc_function_template *ft)
 
return >t;
 }
-EXPORT_SYMBOL(fc_attach_transport);
 
 void fc_release_transport(struct scsi_transport_template *t)
 {
struct fc_internal *i = to_fc_internal(t);
 
+   if (i->f->lightweight_transport)
+