[SCSI] scsi_dh_rdac : decide whether to send mode select based on operating mode

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 <babu.moger@lsi.com>
Reviewed-by: Yanling Qi <yanling.qi@lsi.com>
Reviewed-by: Sudhir Dachepalli <Sudhir.Dachepalli@lis.com>
Reviewed-by: Somasundaram Krishnasamy <Somasundaram.Krishnasamy@lsi.com>
Reviewed-by: Bob Stankey <Robert.Stankey@lsi.com>
Reviewed-by: Vijay Chauhan <Vijay.Chauhan@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 4efe638036f6..e7fc70d6b478 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -670,12 +670,27 @@ static int rdac_activate(struct scsi_device *sdev,
 {
         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;