Subject: root fs timestamp does not get updated (#130)
Index:	sys/ufs_subr.c 2.11BSD

Description:
	The root filesystem's timestamp can fall seriously short of the
	real time of day.  If a powerfail occurs (and battery backup is
	present) and a autoreboot is done, the time of day can be several
	hours off.

Repeat-By:
	There are several ways, the one below is how the problem was
	first spotted.

	Have a quiescent root filesystem (no files created or removed, etc)
	for several hours before a powerfail.  After the autoreboot following
	restoration of power note that the system's time is very incorrect.

Fix:
	Apply the small patch below to ufs_subr.c, remake and install the
	kernel.

	Superblocks are only updated to disc if something has changed. 

	The problem is that on a system where /tmp is a separate partition
	of its own there is *very* little file creation/removal/etc
	taking place on the root filesystem.  Thus the timestamp in the
	root superblock (where the time is picked up after a reboot) can
	fall seriously behind.

	The patch below forces the root fs superblock to be updated when
	a 'sync' call is done.  The 'update' program does a 'sync' call
	once per minute - doing 1 additional disk i/o per minute is not
	likely to cause excessive overhead and it will keep the time current.
============================cut here===============================
*** /sys/sys/ufs_subr.c.old	Thu Dec 24 09:49:00 1992
--- /sys/sys/ufs_subr.c	Sat Mar 20 22:44:34 1993
***************
*** 3,9 ****
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)ufs_subr.c	1.2 (2.11BSD GTE) 12/24/92
   */
  
  #include "param.h"
--- 3,9 ----
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)ufs_subr.c	1.3 (2.11BSD GTE) 3/18/93
   */
  
  #include "param.h"
***************
*** 44,49 ****
--- 44,51 ----
  		if (mp->m_inodp == NULL || mp->m_dev == NODEV)
  			continue;
  		fs = &mp->m_filsys;
+ 		if (mp->m_dev == rootdev)		/* XXX */
+ 			fs->fs_fmod = 1;		/* XXX */
  		if (fs->fs_fmod == 0)
  			continue;
  		if (fs->fs_ronly != 0) {		/* XXX */