scsi: use external buffer for command logging

Use an external buffer for __scsi_print_command() and move command
logging over to use the per-cpu logging buffer.  With that we can
guarantee the command always will always be formatted in one line.
So we can even print out a variable length command correctly across
several lines. Finally rename __scsi_print_command() to
__scsi_format_comment() to better reflect the functionality.

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/ch.c

@@ -195,8 +195,10 @@ ch_do_scsi(scsi_changer *ch, unsigned char *cmd, int cmd_len,
  retry:
 	errno = 0;
 	if (debug) {
-		DPRINTK("command: ");
-		__scsi_print_command(cmd, cmd_len);
+		char logbuf[SCSI_LOG_BUFSIZE];
+
+		__scsi_format_command(logbuf, sizeof(logbuf), cmd, cmd_len);
+		DPRINTK("command: %s", logbuf);
 	}
 
 	result = scsi_execute_req(ch->device, cmd, direction, buffer,