Re: CVS commit: src/sys/kern

[David Young <dyoung%pobox.com@localhost>]

On Wed, Sep 24, 2008 at 01:46:34PM -0400, Thor Lancelot Simon wrote:
> On Wed, Sep 24, 2008 at 07:38:20PM +0700, Robert Elz wrote:
> >     Date:        Wed, 24 Sep 2008 10:07:19 +0000 (UTC)
> >     From:        Andrew Doran <ad%NetBSD.org@localhost>
> >     Message-ID:  <20080924100719.D78AE175D0%cvs.netbsd.org@localhost>
> > 
> >   | Prevent r/w to r/o downgrade until such time as someone has verified all
> >   | the relevant file system code.
> > 
> > Please don't do that - I do rw -> ro "down"grades (I'd call it an 
> > upgrade...)
> > all the time.   As long as you know what's up (that is, to make sure there
> > is no possibility of stale data) it is fine, and causes no problems.
> 
> This also breaks products which run from flash with their filesystems mounted
> read-only most of the time, but remount them read-write in order to write
> back configuration data when it changes.  That is not an uncommon model
> AFAIK and it poses a fairly major problem for me.
> 
> If anyone can give me an idea what actually has to be verified, I can (since
> I have to) put considerable time into it.

Thor,

Your application sounds similar to mine.  I gave up remounting a
read-write filesystem read-only long, long ago, because if I created or
deleted and re-created as few as one or two files, remounted read-only,
and rebooted shortly thereafter, the filesystem had lost the most
recently created files.  I have probably annotated the problem report
with that information.

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933 ext 24