[SCSI] zfcp: add queue_full sysfs attribute

Adds a new sysfs attribute queue_full for adapters that records the number
of incidents where a requests could not be submitted due to insufficient
free space on the request queue.

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Martin Peschke <mp3@de.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
diff --git a/drivers/s390/scsi/zfcp_sysfs.c b/drivers/s390/scsi/zfcp_sysfs.c
index 2e85c6c..7e85757 100644
--- a/drivers/s390/scsi/zfcp_sysfs.c
+++ b/drivers/s390/scsi/zfcp_sysfs.c
@@ -487,10 +487,23 @@
 ZFCP_SHOST_ATTR(seconds_active, "%llu\n",
 		(unsigned long long) stat_info.seconds_act);
 
+static ssize_t zfcp_sysfs_adapter_q_full_show(struct device *dev,
+					      struct device_attribute *attr,
+					      char *buf)
+{
+	struct Scsi_Host *scsi_host = class_to_shost(dev);
+	struct zfcp_adapter *adapter =
+		(struct zfcp_adapter *) scsi_host->hostdata[0];
+
+	return sprintf(buf, "%d\n", atomic_read(&adapter->qdio_outb_full));
+}
+static DEVICE_ATTR(queue_full, S_IRUGO, zfcp_sysfs_adapter_q_full_show, NULL);
+
 struct device_attribute *zfcp_sysfs_shost_attrs[] = {
 	&dev_attr_utilization,
 	&dev_attr_requests,
 	&dev_attr_megabytes,
 	&dev_attr_seconds_active,
+	&dev_attr_queue_full,
 	NULL
 };