Patch "scsi: megaraid_sas: Fix data integrity failure for JBOD (passthrough) devices" has been added to the 4.8-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    scsi: megaraid_sas: Fix data integrity failure for JBOD (passthrough) devices

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scsi-megaraid_sas-fix-data-integrity-failure-for-jbod-passthrough-devices.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1e793f6fc0db920400574211c48f9157a37e3945 Mon Sep 17 00:00:00 2001
From: Kashyap Desai <kashyap.desai@broadcom.com>
Date: Fri, 21 Oct 2016 06:33:32 -0700
Subject: scsi: megaraid_sas: Fix data integrity failure for JBOD (passthrough) devices

From: Kashyap Desai <kashyap.desai@broadcom.com>

commit 1e793f6fc0db920400574211c48f9157a37e3945 upstream.

Commit 02b01e010afe ("megaraid_sas: return sync cache call with
success") modified the driver to successfully complete SYNCHRONIZE_CACHE
commands without passing them to the controller. Disk drive caches are
only explicitly managed by controller firmware when operating in RAID
mode. So this commit effectively disabled writeback cache flushing for
any drives used in JBOD mode, leading to data integrity failures.

[mkp: clarified patch description]

Fixes: 02b01e010afeeb49328d35650d70721d2ca3fd59
Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/megaraid/megaraid_sas_base.c |   13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1713,16 +1713,13 @@ megasas_queue_command(struct Scsi_Host *
 		goto out_done;
 	}
 
-	switch (scmd->cmnd[0]) {
-	case SYNCHRONIZE_CACHE:
-		/*
-		 * FW takes care of flush cache on its own
-		 * No need to send it down
-		 */
+	/*
+	 * FW takes care of flush cache on its own for Virtual Disk.
+	 * No need to send it down for VD. For JBOD send SYNCHRONIZE_CACHE to FW.
+	 */
+	if ((scmd->cmnd[0] == SYNCHRONIZE_CACHE) && MEGASAS_IS_LOGICAL(scmd)) {
 		scmd->result = DID_OK << 16;
 		goto out_done;
-	default:
-		break;
 	}
 
 	return instance->instancet->build_and_issue_cmd(instance, scmd);


Patches currently in stable-queue which might be from kashyap.desai@broadcom.com are

queue-4.8/scsi-megaraid_sas-fix-data-integrity-failure-for-jbod-passthrough-devices.patch