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

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
CC: stable@vger.kernel.org
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>

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 9ff57de..d8b1fbd 100644 (file)
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1700,16 +1700,13 @@ megasas_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)
                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);