[SCSI] fix up request buffer reference in various scsi drivers

Various scsi drivers use scsi_cmnd.buffer and scsi_cmnd.bufflen in their
queuecommand functions.  Those fields are internal storage for the
midlayer only and are used to restore the original payload after
request_buffer and request_bufflen have been overwritten for EH.  Using
the buffer and bufflen fields means they do very broken things in error
handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index a0289ec..9940157 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -2310,7 +2310,7 @@
 #endif
 	}
 
-	qc->nbytes = cmd->bufflen;
+	qc->nbytes = cmd->request_bufflen;
 
 	return 0;
 }
@@ -2500,7 +2500,7 @@
 	 * TODO: find out if we need to do more here to
 	 *       cover scatter/gather case.
 	 */
-	qc->nsect = cmd->bufflen / ATA_SECT_SIZE;
+	qc->nsect = cmd->request_bufflen / ATA_SECT_SIZE;
 
 	return 0;