scsi: introduce a result field in struct scsi_request

This passes on the scsi_cmnd result field to users of passthrough
requests.  Currently we abuse req->errors for this purpose, but that
field will go away in its current form.

Note that the old IDE code abuses the errors field in very creative
ways and stores all kinds of different values in it.  I didn't dare
to touch this magic, so the abuses are brought forward 1:1.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 95c40af..07e5ff3 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -247,10 +247,10 @@ static int ide_cd_breathe(ide_drive_t *drive, struct request *rq)
 
 	struct cdrom_info *info = drive->driver_data;
 
-	if (!rq->errors)
+	if (!scsi_req(rq)->result)
 		info->write_timeout = jiffies +	ATAPI_WAIT_WRITE_BUSY;
 
-	rq->errors = 1;
+	scsi_req(rq)->result = 1;
 
 	if (time_after(jiffies, info->write_timeout))
 		return 0;
@@ -294,8 +294,8 @@ static int cdrom_decode_status(ide_drive_t *drive, u8 stat)
 	}
 
 	/* if we have an error, pass CHECK_CONDITION as the SCSI status byte */
-	if (blk_rq_is_scsi(rq) && !rq->errors)
-		rq->errors = SAM_STAT_CHECK_CONDITION;
+	if (blk_rq_is_scsi(rq) && !scsi_req(rq)->result)
+		scsi_req(rq)->result = SAM_STAT_CHECK_CONDITION;
 
 	if (blk_noretry_request(rq))
 		do_end_request = 1;
@@ -325,7 +325,7 @@ static int cdrom_decode_status(ide_drive_t *drive, u8 stat)
 		 * Arrange to retry the request but be sure to give up if we've
 		 * retried too many times.
 		 */
-		if (++rq->errors > ERROR_MAX)
+		if (++scsi_req(rq)->result > ERROR_MAX)
 			do_end_request = 1;
 		break;
 	case ILLEGAL_REQUEST:
@@ -372,7 +372,7 @@ static int cdrom_decode_status(ide_drive_t *drive, u8 stat)
 			/* go to the default handler for other errors */
 			ide_error(drive, "cdrom_decode_status", stat);
 			return 1;
-		} else if (++rq->errors > ERROR_MAX)
+		} else if (++scsi_req(rq)->result > ERROR_MAX)
 			/* we've racked up too many retries, abort */
 			do_end_request = 1;
 	}
@@ -453,7 +453,7 @@ int ide_cd_queue_pc(ide_drive_t *drive, const unsigned char *cmd,
 		}
 
 		blk_execute_rq(drive->queue, info->disk, rq, 0);
-		error = rq->errors ? -EIO : 0;
+		error = scsi_req(rq)->result ? -EIO : 0;
 
 		if (buffer)
 			*bufflen = scsi_req(rq)->resid_len;
@@ -684,8 +684,8 @@ static ide_startstop_t cdrom_newpc_intr(ide_drive_t *drive)
 			if (cmd->nleft == 0)
 				uptodate = 1;
 		} else {
-			if (uptodate <= 0 && rq->errors == 0)
-				rq->errors = -EIO;
+			if (uptodate <= 0 && scsi_req(rq)->result == 0)
+				scsi_req(rq)->result = -EIO;
 		}
 
 		if (uptodate == 0 && rq->bio)
@@ -1380,7 +1380,7 @@ static int ide_cdrom_prep_pc(struct request *rq)
 	 * appropriate action
 	 */
 	if (c[0] == MODE_SENSE || c[0] == MODE_SELECT) {
-		rq->errors = ILLEGAL_REQUEST;
+		scsi_req(rq)->result = ILLEGAL_REQUEST;
 		return BLKPREP_KILL;
 	}