scsi: zfcp: Handle event-lost notification for Version Change events

As recovery for a lost Version Change event, trigger an Exchange Config
Data cmd to retrieve the current FW version.

Doing so requires process context (as eg. zfcp_qdio_sbal_get() might need
to sleep), so defer from tasklet context into a work item.

Link: https://lore.kernel.org/r/[e-mail]
Suggested-by: Steffen Maier <[e-mail]>
Reviewed-by: Steffen Maier <[e-mail]>
Reviewed-by: Benjamin Block <[e-mail]>
Signed-off-by: Julian Wiedmann <[e-mail]>
Signed-off-by: Benjamin Block <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/s390/scsi/zfcp_aux.c

···
 					     stat_work));
 }
 
+static void zfcp_version_change_lost_work(struct work_struct *work)
+{
+	struct zfcp_adapter *adapter = container_of(work, struct zfcp_adapter,
+						    version_change_lost_work);
+
+	zfcp_fsf_exchange_config_data_sync(adapter->qdio, NULL);
+}
+
 static void zfcp_print_sl(struct seq_file *m, struct service_level *sl)
 {
 	struct zfcp_adapter *adapter =
···
 	INIT_WORK(&adapter->stat_work, _zfcp_status_read_scheduler);
 	INIT_DELAYED_WORK(&adapter->scan_work, zfcp_fc_scan_ports);
 	INIT_WORK(&adapter->ns_up_work, zfcp_fc_sym_name_update);
+	INIT_WORK(&adapter->version_change_lost_work,
+		  zfcp_version_change_lost_work);
 
 	adapter->next_port_scan = jiffies;
 
···
 	cancel_delayed_work_sync(&adapter->scan_work);
 	cancel_work_sync(&adapter->stat_work);
 	cancel_work_sync(&adapter->ns_up_work);
+	cancel_work_sync(&adapter->version_change_lost_work);
 	zfcp_destroy_adapter_work_queue(adapter);
 
 	zfcp_fc_wka_ports_force_offline(adapter->gs);

drivers/s390/scsi/zfcp_def.h

···
 	struct zfcp_fc_events events;
 	unsigned long		next_port_scan;
 	struct zfcp_diag_adapter	*diagnostics;
+	struct work_struct	version_change_lost_work;
 };
 
 struct zfcp_port {

drivers/s390/scsi/zfcp_fsf.c

···
 	case FSF_STATUS_READ_NOTIFICATION_LOST:
 		if (sr_buf->status_subtype & FSF_STATUS_READ_SUB_INCOMING_ELS)
 			zfcp_fc_conditional_port_scan(adapter);
+		if (sr_buf->status_subtype & FSF_STATUS_READ_SUB_VERSION_CHANGE)
+			queue_work(adapter->work_queue,
+				   &adapter->version_change_lost_work);
 		break;
 	case FSF_STATUS_READ_FEATURE_UPDATE_ALERT:
 		adapter->adapter_features = sr_buf->payload.word[0];

drivers/s390/scsi/zfcp_fsf.h

···
 
 /* status subtypes for unsolicited status notification lost */
 #define FSF_STATUS_READ_SUB_INCOMING_ELS	0x00000001
+#define FSF_STATUS_READ_SUB_VERSION_CHANGE	0x00000100
 
 /* status subtypes for version change */
 #define FSF_STATUS_READ_SUB_LIC_CHANGE		0x00000001