Re: CVS commit: src/sys/kern

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    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.

Some of my changes occur hours after the last operations on the relevant
filesystem (if I forget, sometimes even days) - there's no rational chance
there is any unsync'd data (meta or otherwise) left anywhere.   I really
don't want to be prevented from the mount status change because of the
possibility that someone else is switching to ro within seconds of a massive
file delete operation or similar (Aside from anything else, a scan of the
buffer cache to see if there are any dirty blocks from the device in question
shouldn't be hard to code.)

kre