[3/3] scsi_dh_rdac : decide on whether to send mode select or not based on operating mode

Commit Message

babu moger April 8, 2011, 5:39 p.m. UTC

Based on the operating modes, handler decides whether to send mode select or not. Purpose here is to reduce
io-shipping as much as possible whenever there is an option.

Signed-off-by: Babu Moger <[e-mail]>
Reviewed-by: Yanling Qi <[e-mail]> 
Reviewed-by: Sudhir Dachepalli <[e-mail]>
Reviewed-by: Somasundaram Krishnasamy <[e-mail]>
Reviewed-by: Bob Stankey <[e-mail]>
Reviewed-by: Vijay Chauhan <[e-mail]>

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Patch

--- linux-2.6.38/drivers/scsi/device_handler/scsi_dh_rdac.c.orig	2011-03-17 16:57:51.000000000 -0500
+++ linux-2.6.38/drivers/scsi/device_handler/scsi_dh_rdac.c	2011-03-17 16:59:11.000000000 -0500
@@ -670,12 +670,27 @@  static int rdac_activate(struct scsi_dev
 {
 	struct rdac_dh_data *h = get_rdac_data(sdev);
 	int err = SCSI_DH_OK;
+	int act = 0;
 
 	err = check_ownership(sdev, h);
 	if (err != SCSI_DH_OK)
 		goto done;
 
-	if (h->lun_state == RDAC_LUN_UNOWNED) {
+	switch (h->mode) {
+	case RDAC_MODE:
+		if (h->lun_state == RDAC_LUN_UNOWNED)
+			act = 1;
+		break;
+	case RDAC_MODE_IOSHIP:
+		if ((h->lun_state == RDAC_LUN_UNOWNED) &&
+		    (h->preferred == RDAC_PREFERRED))
+			act = 1;
+		break;
+	default:
+		break;
+	}
+
+	if (act) {
 		err = queue_mode_select(sdev, fn, data);
 		if (err == SCSI_DH_OK)
 			return 0;