[SCSI] scsi_dh: Change the scsidh_activate interface to be asynchronous

Make scsi_dh_activate() function asynchronous, by taking in two additional
parameters, one is the callback function and the other is the data to call
the callback function with.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 268189d..be362ad 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -568,7 +568,8 @@
 	return err;
 }
 
-static int rdac_activate(struct scsi_device *sdev)
+static int rdac_activate(struct scsi_device *sdev,
+			activate_complete fn, void *data)
 {
 	struct rdac_dh_data *h = get_rdac_data(sdev);
 	int err = SCSI_DH_OK;
@@ -580,7 +581,9 @@
 	if (h->lun_state == RDAC_LUN_UNOWNED)
 		err = send_mode_select(sdev, h);
 done:
-	return err;
+	if (fn)
+		fn(data, err);
+	return 0;
 }
 
 static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)