[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: <[e-mail]>
Reported-by: Praveen Murali <[e-mail]>
Tested-by: Praveen Murali <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/aic94xx/aic94xx_task.c

···
 
 		if (SAS_STATUS_BUF_SIZE >= sizeof(*resp)) {
 			resp->frame_len = le16_to_cpu(*(__le16 *)(r+6));
-			memcpy(&resp->ending_fis[0], r+16, 24);
+			memcpy(&resp->ending_fis[0], r+16, ATA_RESP_FIS_SIZE);
 			ts->buf_valid_size = sizeof(*resp);
 		}
 	}

drivers/scsi/libsas/sas_ata.c

···
 	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;
 		}
···
 				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;
 		}
 	}
 
···
 {
 	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;
 }
 

include/scsi/libsas.h

···
         ATAPI_COMMAND_SET = 1,
 };
 
+#define ATA_RESP_FIS_SIZE 24
+
 struct sata_device {
         enum   ata_command_set command_set;
         struct smp_resp        rps_resp; /* report_phy_sata_resp */
···
 
 	struct ata_port *ap;
 	struct ata_host ata_host;
-	struct ata_taskfile tf;
+	u8     fis[ATA_RESP_FIS_SIZE];
 };
 
 enum {
···
  */
 struct ata_task_resp {
 	u16  frame_len;
-	u8   ending_fis[24];	  /* dev to host or data-in */
+	u8   ending_fis[ATA_RESP_FIS_SIZE];	  /* dev to host or data-in */
 };
 
 #define SAS_STATUS_BUF_SIZE 96