[SCSI] libsas: fix taskfile corruption in sas_ata_qc_fill_rtf

fill_result_tf() grabs the taskfile flags from the originating qc which
sas_ata_qc_fill_rtf() promptly overwrites.  The presence of an
ata_taskfile in the sata_device makes it tempting to just copy the full
contents in sas_ata_qc_fill_rtf().  However, libata really only wants
the fis contents and expects the other portions of the taskfile to not
be touched by ->qc_fill_rtf.  To that end store a fis buffer in the
sata_device and use ata_tf_from_fis() like every other ->qc_fill_rtf()
implementation.

Cc: <stable@vger.kernel.org>
Reported-by: Praveen Murali <pmurali@logicube.com>
Tested-by: Praveen Murali <pmurali@logicube.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c
index 441d88a..d109cc3 100644
--- a/drivers/scsi/libsas/sas_ata.c
+++ b/drivers/scsi/libsas/sas_ata.c
@@ -139,12 +139,12 @@
 	if (stat->stat == SAS_PROTO_RESPONSE || stat->stat == SAM_STAT_GOOD ||
 	    ((stat->stat == SAM_STAT_CHECK_CONDITION &&
 	      dev->sata_dev.command_set == ATAPI_COMMAND_SET))) {
-		ata_tf_from_fis(resp->ending_fis, &dev->sata_dev.tf);
+		memcpy(dev->sata_dev.fis, resp->ending_fis, ATA_RESP_FIS_SIZE);
 
 		if (!link->sactive) {
-			qc->err_mask |= ac_err_mask(dev->sata_dev.tf.command);
+			qc->err_mask |= ac_err_mask(dev->sata_dev.fis[2]);
 		} else {
-			link->eh_info.err_mask |= ac_err_mask(dev->sata_dev.tf.command);
+			link->eh_info.err_mask |= ac_err_mask(dev->sata_dev.fis[2]);
 			if (unlikely(link->eh_info.err_mask))
 				qc->flags |= ATA_QCFLAG_FAILED;
 		}
@@ -161,8 +161,8 @@
 				qc->flags |= ATA_QCFLAG_FAILED;
 			}
 
-			dev->sata_dev.tf.feature = 0x04; /* status err */
-			dev->sata_dev.tf.command = ATA_ERR;
+			dev->sata_dev.fis[3] = 0x04; /* status err */
+			dev->sata_dev.fis[2] = ATA_ERR;
 		}
 	}
 
@@ -269,7 +269,7 @@
 {
 	struct domain_device *dev = qc->ap->private_data;
 
-	memcpy(&qc->result_tf, &dev->sata_dev.tf, sizeof(qc->result_tf));
+	ata_tf_from_fis(dev->sata_dev.fis, &qc->result_tf);
 	return true;
 }