[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>

drivers/s390/scsi/zfcp_def.h

@@ -568,6 +568,7 @@ struct zfcp_adapter {
 	struct fsf_qtcb_bottom_port *stats_reset_data;
 	unsigned long		stats_reset;
 	struct work_struct	scan_work;
+	atomic_t		qdio_outb_full;	   /* queue full incidents */
 };
 
 struct zfcp_port {

drivers/s390/scsi/zfcp_fsf.c

@@ -717,6 +717,14 @@ static int zfcp_fsf_sbal_check(struct zfcp_qdio_queue *queue)
 	return 0;
 }
 
+static int zfcp_fsf_sbal_available(struct zfcp_adapter *adapter)
+{
+	unsigned int count = atomic_read(&adapter->req_q.count);
+	if (!count)
+		atomic_inc(&adapter->qdio_outb_full);
+	return count > 0;
+}
+
 static int zfcp_fsf_req_sbal_get(struct zfcp_adapter *adapter)
 {
 	long ret;
@@ -727,6 +735,8 @@ static int zfcp_fsf_req_sbal_get(struct zfcp_adapter *adapter)
 					zfcp_fsf_sbal_check(req_q), 5 * HZ);
 	if (ret > 0)
 		return 0;
+	if (!ret)
+		atomic_inc(&adapter->qdio_outb_full);
 
 	spin_lock_bh(&req_q->lock);
 	return -EIO;
@@ -984,7 +994,7 @@ struct zfcp_fsf_req *zfcp_fsf_abort_fcp_command(unsigned long old_req_id,
 	struct zfcp_fsf_req *req = NULL;
 
 	spin_lock(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_ABORT_FCP_CMND,
 				  req_flags, adapter->pool.fsf_req_abort);
@@ -1219,7 +1229,7 @@ int zfcp_fsf_send_els(struct zfcp_send_els *els)
 		return -EBUSY;
 
 	spin_lock(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_SEND_ELS,
 				  ZFCP_REQ_AUTO_CLEANUP, NULL);
@@ -1264,7 +1274,7 @@ int zfcp_fsf_exchange_config_data(struct zfcp_erp_action *erp_action)
 	int retval = -EIO;
 
 	spin_lock_bh(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter,
 				  FSF_QTCB_EXCHANGE_CONFIG_DATA,
@@ -1360,7 +1370,7 @@ int zfcp_fsf_exchange_port_data(struct zfcp_erp_action *erp_action)
 		return -EOPNOTSUPP;
 
 	spin_lock_bh(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_EXCHANGE_PORT_DATA,
 				  ZFCP_REQ_AUTO_CLEANUP,
@@ -1406,7 +1416,7 @@ int zfcp_fsf_exchange_port_data_sync(struct zfcp_adapter *adapter,
 		return -EOPNOTSUPP;
 
 	spin_lock_bh(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_EXCHANGE_PORT_DATA, 0,
@@ -2224,7 +2234,7 @@ int zfcp_fsf_send_fcp_command_task(struct zfcp_adapter *adapter,
 		return -EBUSY;
 
 	spin_lock(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_FCP_CMND, req_flags,
 				  adapter->pool.fsf_req_scsi);
@@ -2347,7 +2357,7 @@ struct zfcp_fsf_req *zfcp_fsf_send_fcp_ctm(struct zfcp_adapter *adapter,
 		return NULL;
 
 	spin_lock(&adapter->req_q.lock);
-	if (!atomic_read(&adapter->req_q.count))
+	if (!zfcp_fsf_sbal_available(adapter))
 		goto out;
 	req = zfcp_fsf_req_create(adapter, FSF_QTCB_FCP_CMND, req_flags,
 				  adapter->pool.fsf_req_scsi);

drivers/s390/scsi/zfcp_qdio.c

@@ -282,6 +282,7 @@ static int zfcp_qdio_fill_sbals(struct zfcp_fsf_req *fsf_req,
 	     addr += length, remaining -= length) {
 		sbale = zfcp_qdio_sbale_next(fsf_req, sbtype);
 		if (!sbale) {
+			atomic_inc(&fsf_req->adapter->qdio_outb_full);
 			zfcp_qdio_undo_sbals(fsf_req);
 			return -EINVAL;
 		}

drivers/s390/scsi/zfcp_sysfs.c

@@ -487,10 +487,23 @@ ZFCP_SHOST_ATTR(megabytes, "%llu %llu\n",
 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
 };