scsi: log request tag for scmd_printk()

The request tag provides a concise identification of a SCSI
command, so we should be printing that out for scmd_printk().

Suggested-by: Christoph Hellwig <hch@lst.de>
Tested-by: Robert Elliott <elliott@hp.com>
Reviewed-by: Robert Elliott <elliott@hp.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/scsi/scsi_logging.c

@@ -114,6 +114,10 @@ int scmd_printk(const char *level, const struct scsi_cmnd *scmd,
 	if (disk)
 		off += scnprintf(logbuf + off, logbuf_len - off,
 				 "[%s] ", disk->disk_name);
+
+	if (scmd->request->tag >= 0)
+		off += scnprintf(logbuf + off, logbuf_len - off,
+				 "tag#%d ", scmd->request->tag);
 	va_start(args, fmt);
 	off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
 	va_end(args);