Re: [PATCH] scsi_transport_fc: Make 'port_state' writeable

[Steffen Maier <maier@linux.vnet.ibm.com>]

Just for my understanding:
So this is a bit like writing 0 into the failed attribute of a zfcp_port 
in sysfs (zfcp_sysfs_port_failed_store()) which forces a port reopen 
recovery including a sequence of fc_remote_port_delete and 
fc_remote_port_add?
If so, it sounds good to have this functionality for any FC LLD in 
common code.
(And I can think about deprecating parts of zfcp code, next we could 
consider the same for zfcp's forced LUN and adapter recovery or maybe 
this already exists as sdev's writable state attribute and the adapter 
recovery can be performed manually by walking all fc_rports writing 
their port_state.)

On 01/15/2013 04:02 PM, Hannes Reinecke wrote:
> Multipath might detect a path down even though the LLDD
> hasn't registered a link down event.
> This patch makes the 'port_state' FC attribute writeable
> to enforce a link down scenario in these cases, allowing
> for a fast failover to the remaining ports.
>
> Cc: Chad Dupuis <chad.dupuis@qlogic.com>
> Cc: Andrew Vasquez <andrew.vasquez@qlogic.com>
> Cc: James Smart <james.smart@emulex.com>
> Cc: James Bottomley <jbottomley@parallels.com>
> Cc: Mike Christie <michaelc@cs.wisc.edu>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
>
> diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> index 5e1c6dd..4d28ee5 100644
> --- a/drivers/scsi/scsi_transport_fc.c
> +++ b/drivers/scsi/scsi_transport_fc.c
> @@ -42,6 +42,8 @@
>   #include "scsi_priv.h"
>   #include "scsi_transport_fc_internal.h"
>
> +static void fc_flush_devloss(struct Scsi_Host *shost);
> +static void fc_flush_work(struct Scsi_Host *shost);
>   static int fc_queue_work(struct Scsi_Host *, struct work_struct *);
>   static void fc_vport_sched_delete(struct work_struct *work);
>   static int fc_vport_setup(struct Scsi_Host *shost, int channel,
> @@ -949,7 +951,76 @@ show_fc_rport_roles (struct device *dev, struct device_attribute *attr,
>   static FC_DEVICE_ATTR(rport, roles, S_IRUGO,
>   		show_fc_rport_roles, NULL);
>
> -fc_private_rport_rd_enum_attr(port_state, FC_PORTSTATE_MAX_NAMELEN);
> +static ssize_t
> +store_fc_rport_port_state(struct device *dev,
> +			  struct device_attribute *attr,
> +			  const char *buf, size_t count)
> +{
> +	unsigned long flags;
> +	struct fc_rport *rport = transport_class_to_rport(dev);
> +	struct Scsi_Host *shost = rport_to_shost(rport);
> +
> +	spin_lock_irqsave(shost->host_lock, flags);
> +	if (!strncmp(buf, "Blocked", 7)) {
> +		if (rport->port_state != FC_PORTSTATE_ONLINE) {
> +			spin_unlock_irqrestore(shost->host_lock, flags);
> +			return -EBUSY;
> +		}
> +		spin_unlock_irqrestore(shost->host_lock, flags);
> +		fc_remote_port_delete(rport);
> +	} else if (!strncmp(buf, "Online", 6)) {
> +		if (rport->port_state != FC_PORTSTATE_BLOCKED) {
> +			spin_unlock_irqrestore(shost->host_lock, flags);
> +			return -EBUSY;
> +		}
> +		/* Reset back to online for rescan */
> +		rport->port_state = FC_PORTSTATE_ONLINE;
> +		spin_unlock_irqrestore(shost->host_lock, flags);
> +
> +		if (!cancel_delayed_work(&rport->fail_io_work))
> +			fc_flush_devloss(shost);
> +		if (!cancel_delayed_work(&rport->dev_loss_work))
> +			fc_flush_devloss(shost);
> +
> +		spin_lock_irqsave(shost->host_lock, flags);
> +		rport->flags &= ~(FC_RPORT_FAST_FAIL_TIMEDOUT |
> +				  FC_RPORT_DEVLOSS_PENDING |
> +				  FC_RPORT_DEVLOSS_CALLBK_DONE);
> +		spin_unlock_irqrestore(shost->host_lock, flags);
> +
> +		/* ensure any stgt delete functions are done */
> +		fc_flush_work(shost);
> +
> +		if (rport->roles & FC_PORT_ROLE_FCP_TARGET) {
> +			scsi_target_unblock(&rport->dev, SDEV_RUNNING);
> +			/* initiate a scan of the target */
> +			spin_lock_irqsave(shost->host_lock, flags);
> +			rport->flags |= FC_RPORT_SCAN_PENDING;
> +			scsi_queue_work(shost, &rport->scan_work);
> +			spin_unlock_irqrestore(shost->host_lock, flags);
> +		}
> +	} else
> +		return -EINVAL;
> +
> +	return count;
> +}
> +
> +static ssize_t
> +show_fc_rport_port_state (struct device *dev,
> +			  struct device_attribute *attr, char *buf)
> +{
> +	struct fc_rport *rport = transport_class_to_rport(dev);
> +	const char *name;
> +
> +	name = get_fc_port_state_name(rport->port_state);
> +	if (!name)
> +		return -EINVAL;
> +	return snprintf(buf, FC_PORTSTATE_MAX_NAMELEN, "%s\n", name);
> +}
> +
> +static FC_DEVICE_ATTR(rport, port_state, S_IRUGO | S_IWUSR,
> +		show_fc_rport_port_state, store_fc_rport_port_state);
> +
>   fc_private_rport_rd_attr(scsi_target_id, "%d\n", 20);
>
>   /*
> @@ -2289,7 +2360,7 @@ fc_attach_transport(struct fc_function_template *ft)
>   	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_RW(port_state);
>   	SETUP_PRIVATE_RPORT_ATTRIBUTE_RD(scsi_target_id);
>   	SETUP_PRIVATE_RPORT_ATTRIBUTE_RW(fast_io_fail_tmo);
>
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-- 
Mit freundlichen Grüßen / Kind regards
Steffen Maier

Linux on System z Development

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