[SCSI] scsi_dh_alua: Retry the check-condition in case Mode Parameters Changed

This patch adds a check-condition in scsi_dh_alua handler for a retry.
Sometimes, I have seen attach failing due to this check-condition with
following error messages on NetApp E series storage.

Dec  7 15:31:01 nilgiris kernel: [102979.696673] scsi 3:0:2:9: alua: port group 00 rel port 01
Dec  7 15:31:01 nilgiris kernel: [102979.697082] scsi 3:0:2:9: alua: rtpg failed with 8000002
Dec  7 15:31:01 nilgiris kernel: [102979.697086] scsi 3:0:2:9: alua: rtpg sense code 06/2a/01
Dec  7 15:31:01 nilgiris kernel: [102979.697088] scsi 3:0:2:9: alua: not attached

Signed-off-by: Babu Moger <babu.moger@netapp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/device_handler/scsi_dh_alua.c

@@ -466,6 +466,11 @@ static int alua_check_sense(struct scsi_device *sdev,
 			 * Power On, Reset, or Bus Device Reset, just retry.
 			 */
 			return ADD_TO_MLQUEUE;
+		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
+			/*
+			 * Mode Parameters Changed
+			 */
+			return ADD_TO_MLQUEUE;
 		if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06)
 			/*
 			 * ALUA state changed