[dm-devel] [PATCH] scsi_dh_alua: Retry the check-condition in case Mode Parameters Changed

[Moger, Babu]

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 at netapp.com>
---

--- linux-3.2-rc6/drivers/scsi/device_handler/scsi_dh_alua.c.orig
2011-12-21 15:48:46.000000000 -0600
+++ linux-3.2-rc6/drivers/scsi/device_handler/scsi_dh_alua.c
2011-12-21 16:03:56.000000000 -0600
@@ -466,6 +466,11 @@ static int alua_check_sense(struct scsi_
 			 * 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