Message-ID: <5673C893.6020204@suse.de>
Date:	Fri, 18 Dec 2015 09:49:23 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	"K. Y. Srinivasan" <kys@...rosoft.com>, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
	ohering@...e.com, jbottomley@...allels.com, hch@...radead.org,
	linux-scsi@...r.kernel.org, apw@...onical.com, vkuznets@...hat.com,
	jasowang@...hat.com, martin.petersen@...cle.com
Subject: Re: [PATCH V3 2/4] scsi: storvsc: Properly support Fibre Channel
 devices

On 12/13/2015 09:28 PM, K. Y. Srinivasan wrote:
> For FC devices managed by this driver, atttach the appropriate transport
> template. This will allow us to create the appropriate sysfs files for
> these devices. With this we can publish the wwn for both the port and the node.
>
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> Reviewed-by: Long Li <longli@...rosoft.com>
> Tested-by: Alex Ng <alexng@...rosoft.com>
> ---
> 	V2: Fixed error paths - Dan Carpenter <dan.carpenter@...cle.com>
> 	V3: Fixed build issues reported by kbuild test robot <lkp@...el.com>
>
>   drivers/scsi/storvsc_drv.c |  181 ++++++++++++++++++++++++++++++++-----------
>   1 files changed, 134 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 00bb4bd..220b794 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -41,6 +41,7 @@
>   #include <scsi/scsi_eh.h>
>   #include <scsi/scsi_devinfo.h>
>   #include <scsi/scsi_dbg.h>
> +#include <scsi/scsi_transport_fc.h>
>
>   /*
>    * All wire protocol details (storage protocol between the guest and the host)
> @@ -397,6 +398,9 @@ static int storvsc_timeout = 180;
>
>   static int msft_blist_flags = BLIST_TRY_VPD_PAGES;
>
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +static struct scsi_transport_template *fc_transport_template;
> +#endif
>
>   static void storvsc_on_channel_callback(void *context);
>
> @@ -456,6 +460,11 @@ struct storvsc_device {
>   	/* Used for vsc/vsp channel reset process */
>   	struct storvsc_cmd_request init_request;
>   	struct storvsc_cmd_request reset_request;
> +	/*
> +	 * Currently active port and node names for FC devices.
> +	 */
> +	u64 node_name;
> +	u64 port_name;
>   };
>
>   struct hv_host_device {
> @@ -695,7 +704,26 @@ static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
>   	vmbus_are_subchannels_present(device->channel);
>   }
>
> -static int storvsc_channel_init(struct hv_device *device)
> +static void cache_wwn(struct storvsc_device *stor_device,
> +		      struct vstor_packet *vstor_packet)
> +{
> +	/*
> +	 * Cache the currently active port and node ww names.
> +	 */
> +	if (vstor_packet->wwn_packet.primary_active) {
> +		stor_device->node_name =
> +			wwn_to_u64(vstor_packet->wwn_packet.primary_node_wwn);
> +		stor_device->port_name =
> +			wwn_to_u64(vstor_packet->wwn_packet.primary_port_wwn);
> +	} else {
> +		stor_device->node_name =
> +			wwn_to_u64(vstor_packet->wwn_packet.secondary_node_wwn);
> +		stor_device->port_name =
> +			wwn_to_u64(vstor_packet->wwn_packet.secondary_port_wwn);
> +	}
> +}
> +
> +static int storvsc_channel_init(struct hv_device *device, bool is_fc)
>   {
>   	struct storvsc_device *stor_device;
>   	struct storvsc_cmd_request *request;
> @@ -727,19 +755,15 @@ static int storvsc_channel_init(struct hv_device *device)
>   			       VM_PKT_DATA_INBAND,
>   			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>   	if (ret != 0)
> -		goto cleanup;
> +		return ret;
>
>   	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
> -	if (t == 0) {
> -		ret = -ETIMEDOUT;
> -		goto cleanup;
> -	}
> +	if (t == 0)
> +		return -ETIMEDOUT;
>
>   	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
> -	    vstor_packet->status != 0) {
> -		ret = -EINVAL;
> -		goto cleanup;
> -	}
> +	    vstor_packet->status != 0)
> +		return -EINVAL;
>
>
>   	for (i = 0; i < ARRAY_SIZE(vmstor_protocols); i++) {
> @@ -764,18 +788,14 @@ static int storvsc_channel_init(struct hv_device *device)
>   			       VM_PKT_DATA_INBAND,
>   			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>   		if (ret != 0)
> -			goto cleanup;
> +			return ret;
>
>   		t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
> -		if (t == 0) {
> -			ret = -ETIMEDOUT;
> -			goto cleanup;
> -		}
> +		if (t == 0)
> +			return -ETIMEDOUT;
>
> -		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO) {
> -			ret = -EINVAL;
> -			goto cleanup;
> -		}
> +		if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO)
> +			return -EINVAL;
>
>   		if (vstor_packet->status == 0) {
>   			vmstor_proto_version =
> @@ -791,10 +811,8 @@ static int storvsc_channel_init(struct hv_device *device)
>   		}
>   	}
>
> -	if (vstor_packet->status != 0) {
> -		ret = -EINVAL;
> -		goto cleanup;
> -	}
> +	if (vstor_packet->status != 0)
> +		return -EINVAL;
>
>
>   	memset(vstor_packet, 0, sizeof(struct vstor_packet));
> @@ -809,19 +827,15 @@ static int storvsc_channel_init(struct hv_device *device)
>   			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>
>   	if (ret != 0)
> -		goto cleanup;
> +		return ret;
>
>   	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
> -	if (t == 0) {
> -		ret = -ETIMEDOUT;
> -		goto cleanup;
> -	}
> +	if (t == 0)
> +		return -ETIMEDOUT;
>
>   	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
> -	    vstor_packet->status != 0) {
> -		ret = -EINVAL;
> -		goto cleanup;
> -	}
> +	    vstor_packet->status != 0)
> +		return -EINVAL;
>
>   	/*
>   	 * Check to see if multi-channel support is there.
> @@ -837,6 +851,38 @@ static int storvsc_channel_init(struct hv_device *device)
>   	stor_device->max_transfer_bytes =
>   		vstor_packet->storage_channel_properties.max_transfer_bytes;
>
> +	if (!is_fc)
> +		goto done;
> +
> +	memset(vstor_packet, 0, sizeof(struct vstor_packet));
> +	vstor_packet->operation = VSTOR_OPERATION_FCHBA_DATA;
> +	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
> +
> +	ret = vmbus_sendpacket(device->channel, vstor_packet,
> +			       (sizeof(struct vstor_packet) -
> +			       vmscsi_size_delta),
> +			       (unsigned long)request,
> +			       VM_PKT_DATA_INBAND,
> +			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
> +
> +	if (ret != 0)
> +		return ret;
> +
> +	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
> +	if (t == 0)
> +		return -ETIMEDOUT;
> +
> +	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
> +	    vstor_packet->status != 0)
> +		return -EINVAL;
> +
> +	/*
> +	 * Cache the currently active port and node ww names.
> +	 */
> +	cache_wwn(stor_device, vstor_packet);
> +
> +done:
> +
>   	memset(vstor_packet, 0, sizeof(struct vstor_packet));
>   	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
>   	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
> @@ -849,25 +895,19 @@ static int storvsc_channel_init(struct hv_device *device)
>   			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
>
>   	if (ret != 0)
> -		goto cleanup;
> +		return ret;
>
>   	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
> -	if (t == 0) {
> -		ret = -ETIMEDOUT;
> -		goto cleanup;
> -	}
> +	if (t == 0)
> +		return -ETIMEDOUT;
>
>   	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
> -	    vstor_packet->status != 0) {
> -		ret = -EINVAL;
> -		goto cleanup;
> -	}
> +	    vstor_packet->status != 0)
> +		return -EINVAL;
>
>   	if (process_sub_channels)
>   		handle_multichannel_storage(device, max_chns);
>
> -
> -cleanup:
>   	return ret;
>   }
>
> @@ -1076,6 +1116,14 @@ static void storvsc_on_receive(struct hv_device *device,
>   		schedule_work(&work->work);
>   		break;
>
> +	case VSTOR_OPERATION_FCHBA_DATA:
> +		stor_device = get_in_stor_device(device);
> +		cache_wwn(stor_device, vstor_packet);
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +		fc_host_node_name(stor_device->host) = stor_device->node_name;
> +		fc_host_port_name(stor_device->host) = stor_device->port_name;
> +#endif
> +		break;
>   	default:
>   		break;
>   	}
> @@ -1131,7 +1179,8 @@ static void storvsc_on_channel_callback(void *context)
>   	return;
>   }
>
> -static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
> +static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size,
> +				  bool is_fc)
>   {
>   	struct vmstorage_channel_properties props;
>   	int ret;
> @@ -1148,7 +1197,7 @@ static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
>   	if (ret != 0)
>   		return ret;
>
> -	ret = storvsc_channel_init(device);
> +	ret = storvsc_channel_init(device, is_fc);
>
>   	return ret;
>   }
> @@ -1573,6 +1622,7 @@ static int storvsc_probe(struct hv_device *device,
>   	struct Scsi_Host *host;
>   	struct hv_host_device *host_dev;
>   	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
> +	bool is_fc = ((dev_id->driver_data == SFC_GUID) ? true : false);
>   	int target = 0;
>   	struct storvsc_device *stor_device;
>   	int max_luns_per_target;
> @@ -1630,7 +1680,7 @@ static int storvsc_probe(struct hv_device *device,
>   	hv_set_drvdata(device, stor_device);
>
>   	stor_device->port_number = host->host_no;
> -	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
> +	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size, is_fc);
>   	if (ret)
>   		goto err_out1;
>
> @@ -1642,6 +1692,9 @@ static int storvsc_probe(struct hv_device *device,
>   		host->max_lun = STORVSC_FC_MAX_LUNS_PER_TARGET;
>   		host->max_id = STORVSC_FC_MAX_TARGETS;
>   		host->max_channel = STORVSC_FC_MAX_CHANNELS - 1;
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +		host->transportt = fc_transport_template;
> +#endif
>   		break;
>
>   	case SCSI_GUID:
> @@ -1681,6 +1734,12 @@ static int storvsc_probe(struct hv_device *device,
>   			goto err_out2;
>   		}
>   	}
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +	if (host->transportt == fc_transport_template) {
> +		fc_host_node_name(host) = stor_device->node_name;
> +		fc_host_port_name(host) = stor_device->port_name;
> +	}
> +#endif
>   	return 0;
>
>   err_out2:
> @@ -1706,6 +1765,10 @@ static int storvsc_remove(struct hv_device *dev)
>   	struct storvsc_device *stor_device = hv_get_drvdata(dev);
>   	struct Scsi_Host *host = stor_device->host;
>
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +	if (host->transportt == fc_transport_template)
> +		fc_remove_host(host);
> +#endif
>   	scsi_remove_host(host);
>   	storvsc_dev_remove(dev);
>   	scsi_host_put(host);
> @@ -1720,8 +1783,16 @@ static struct hv_driver storvsc_drv = {
>   	.remove = storvsc_remove,
>   };
>
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +static struct fc_function_template fc_transport_functions = {
> +	.show_host_node_name = 1,
> +	.show_host_port_name = 1,
> +};
> +#endif
> +
>   static int __init storvsc_drv_init(void)
>   {
> +	int ret;
>
>   	/*
>   	 * Divide the ring buffer data size (which is 1 page less
> @@ -1736,12 +1807,28 @@ static int __init storvsc_drv_init(void)
>   		vmscsi_size_delta,
>   		sizeof(u64)));
>
> -	return vmbus_driver_register(&storvsc_drv);
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +	fc_transport_template = fc_attach_transport(&fc_transport_functions);
> +	if (!fc_transport_template)
> +		return -ENODEV;
> +#endif
> +
> +	ret = vmbus_driver_register(&storvsc_drv);
> +
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +	if (ret)
> +		fc_release_transport(fc_transport_template);
> +#endif
> +
> +	return ret;
>   }
>
>   static void __exit storvsc_drv_exit(void)
>   {
>   	vmbus_driver_unregister(&storvsc_drv);
> +#ifdef CONFIG_SCSI_FC_ATTRS
> +	fc_release_transport(fc_transport_template);
> +#endif
>   }
>
>   MODULE_LICENSE("GPL");
>
Well.
This would _always_ attach the FC template to the storvsc driver, 
even if it not used. Typically one would be using a separate driver 
for that, but hey.

_However_: How should you handle FC attached devices if the FC 
transport template is _NOT_ selected?
By rights one would expect the driver to not handle those devices; 
but looking at the code this doesn't happen.

What I would like to see is a clear separation here:
- Disable FC disk handling if FC attributes are not configured
- Add a module parameter allowing to disable FC attributes even if 
they are compiled in. Remember: this is a virtualized guest, and 
people might want so save kernel memory wherever they can. So always 
attaching to the fc transport template will make them very unhappy.
Alternatively you could split out FC device handling into a separate 
driver, but seeing the diff that's probably overkill.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@...e.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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