[SCSI] zfcp: fix device registration issues

The patch fixes following issues:

(1) Replace scsi_add_device with scsi_scan_target.
(Thus the rport instead of the scsi_host becomes parent of a
scsi_target again.)

(2) Avoid scsi_device allocation during registration of an remote port.
(Would be done during fc_scsi_scan_rport.)

(3) Fix queuecommand behaviour when an zfcp unit is blocked.
(Call scsi_done with DID_NO_CONNECT instead of returning
SCSI_MLQUEUE_DEVICE_BUSY otherwise we might end up waiting
for completion in blk_execute_rq for ever.)

Signed-off-by: Andreas Herrmann <aherrman@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/s390/scsi/zfcp_def.h

@@ -664,6 +664,7 @@ do { \
 #define ZFCP_STATUS_UNIT_TEMPORARY		0x00000002
 #define ZFCP_STATUS_UNIT_SHARED			0x00000004
 #define ZFCP_STATUS_UNIT_READONLY		0x00000008
+#define ZFCP_STATUS_UNIT_REGISTERED		0x00000010
 
 /* FSF request status (this does not have a common part) */
 #define ZFCP_STATUS_FSFREQ_NOT_INIT		0x00000000

drivers/s390/scsi/zfcp_erp.c

@@ -3391,10 +3391,13 @@ zfcp_erp_action_cleanup(int action, struct zfcp_adapter *adapter,
 		    && (!atomic_test_mask(ZFCP_STATUS_UNIT_TEMPORARY,
 					  &unit->status))
 		    && !unit->device
-		    && port->rport)
- 			scsi_add_device(port->adapter->scsi_host, 0,
- 					port->rport->scsi_target_id,
-					unit->scsi_lun);
+		    && port->rport) {
+			atomic_set_mask(ZFCP_STATUS_UNIT_REGISTERED,
+					&unit->status);
+ 			scsi_scan_target(&port->rport->dev, 0,
+					 port->rport->scsi_target_id,
+					 unit->scsi_lun, 0);
+		}
 		zfcp_unit_put(unit);
 		break;
 	case ZFCP_ERP_ACTION_REOPEN_PORT_FORCED:

drivers/s390/scsi/zfcp_scsi.c

@@ -183,7 +183,8 @@ zfcp_scsi_slave_alloc(struct scsi_device *sdp)
 
 	read_lock_irqsave(&zfcp_data.config_lock, flags);
 	unit = zfcp_unit_lookup(adapter, sdp->channel, sdp->id, sdp->lun);
-	if (unit) {
+	if (unit && atomic_test_mask(ZFCP_STATUS_UNIT_REGISTERED,
+				     &unit->status)) {
 		sdp->hostdata = unit;
 		unit->device = sdp;
 		zfcp_unit_get(unit);
@@ -208,6 +209,7 @@ zfcp_scsi_slave_destroy(struct scsi_device *sdpnt)
 	struct zfcp_unit *unit = (struct zfcp_unit *) sdpnt->hostdata;
 
 	if (unit) {
+		atomic_clear_mask(ZFCP_STATUS_UNIT_REGISTERED, &unit->status);
 		sdpnt->hostdata = NULL;
 		unit->device = NULL;
 		zfcp_unit_put(unit);
@@ -291,7 +293,7 @@ zfcp_scsi_command_async(struct zfcp_adapter *adapter, struct zfcp_unit *unit,
 			       "on port 0x%016Lx in recovery\n",
 			       zfcp_get_busid_by_unit(unit),
 			       unit->fcp_lun, unit->port->wwpn);
-		retval = SCSI_MLQUEUE_DEVICE_BUSY;
+		zfcp_scsi_command_fail(scpnt, DID_NO_CONNECT);
 		goto out;
 	}