Date: Fri, 20 Apr 2001 23:57:05 +0200 From: Sven Huster <sven.huster@mailsurf.com> To: Brian Dean <bsd@bsdhome.com>, Luigi Rizzo <luigi@info.iet.unipi.it> Cc: "David E. Cross" <crossd@cs.rpi.edu>, Jordan Hubbard <jkh@osd.bsdi.com>, stable@FreeBSD.ORG, developers@FreeBSD.ORG Subject: Re: FreeBSD 4.3-RC5 now on ftp.freebsd.org Message-ID: <5.0.2.1.0.20010420235117.00a64cb0@mx01.mailsurf.com> In-Reply-To: <20010420111151.A55293@vger.bsdhome.com> References: <200104192325.BAA63867@info.iet.unipi.it> <200104192001.QAA60154@cs.rpi.edu> <200104192325.BAA63867@info.iet.unipi.it>
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Hi
but if you dont umount /tmp at the end we wont have to
mount_null problem (rc.diskless2) with /tmp too in standard setup.
so we can remove this there.
for sure you can replace /tmp with a symlink to /var/tmp
but that wouldnt be done by the normal mtree script, i think.
btw: not my patches, they were posted by someone else as a reply to my
question.
regards
Sven
At 17:11 20.04.2001, Brian Dean wrote:
>*This message was transferred with a trial version of CommuniGate(tm) Pro*
>On Fri, Apr 20, 2001 at 01:25:07AM +0200, Luigi Rizzo wrote:
> > [Jordan, in case we reach consensus on what to do and can test
> > patches before the release's cut date, do we have permission to
> > update rc.diskless{1,2} as needed ? These files are not on a critical
> > part of the system so commits in this area do not pose stability
> > problems.]
> >
> > I had a look at Sven's patches, and there is one thing that puzzles
> > me: when doing the mount_mfs of /etc and restoring files, the
> > OS has still handles open on the old /etc/rc and /etc/rc.diskless1 .
> >
> > What happens on subsequent reads from these files (which are long) ?
> > Do they refer to the old version, the new one, or what ?
> >
> > The problem did not arise with mount_null because themount was simply
> > an overlay so (unless the user would override those files as well)
> > it was clear that the reverence was to the old one.
> >
> > That said: i read the recent commit logs for nullfs in -current,
> > ant it seems to be fixed there, unfortunately i have no idea
> > how hard it is to backport the fixes, some of the diffs are
> > trivial to understand, some are beyond my (very limited)
> > understanding of this part of the kernel.
> >
> > As for stability of the diskless clients:
> > with the current version of rc.diskless2 in -stable, the only part
> > which uses mount_null is /etc/ where hopefully nothing gets written
> > to after the pass in /etc/rc.diskless1 so it should not be
> > a terrible stability issue.
> >
> > cheers
> > luigi
>
>Hi,
>
>I haven't seen Sven's patches, but the following works well here for
>me. The following patch eliminates the null mount by first copying
>/etc/* to /tmp/etc, then we mount /etc as an MFS, then copy back from
>/tmp/etc. The rest of the code proceeds as normal except that copies
>from /conf/*/etc go directly to /etc.
>
>This works well here and does not suffer the problems of the null
>mount. For example, one can run pwd_mkdb without causing a panic,
>etc.
>
>I'd be happy commit this if there is agreement.
>
>-Brian
>--
>Brian Dean
>bsd@FreeBSD.org
>bsd@bsdhome.com
>
>
>Index: rc.diskless1
>===================================================================
>RCS file: /home/ncvs/src/etc/rc.diskless1,v
>retrieving revision 1.7
>diff -u -r1.7 rc.diskless1
>--- rc.diskless1 2001/04/03 00:24:01 1.7
>+++ rc.diskless1 2001/04/20 15:08:16
>@@ -87,39 +87,50 @@
> fi
> done
> echo "Interface ${bootp_ifc} IP-Address ${bootp_ipa} Broadcast
> ${bootp_ipbca}"
>-
>-# Files in /etc are copied to /conf/etc which is writable. Then
>-# per-machine configs from /conf/ip.address/etc are copied onto this
>-# directory. First choice is using the client's IP, then the client's
>-# broadcast address, then a default configuration.
>+
>+
>+
>+# Create an MFS /tmp to temporarily hold files from /etc until we
>+# can bootstrap /etc as an MFS.
>+
>+/sbin/mount_mfs -s 4096 -T qp120at dummy /tmp
>+chkerr $? "MFS mount on /tmp"
>+mkdir /tmp/etc
>+/bin/cp -Rp /etc /tmp
>+chkerr $? "cp /etc to /tmp/etc MFS"
>+
>+/sbin/mount_mfs -s 4096 -T qp120at dummy /etc
>+chkerr $? "MFS mount on /etc"
>+/bin/chmod 755 /etc
>+
>+/bin/cp -Rp /tmp/etc/* /etc
>+chkerr $? "cp /tmp/etc to /etc MFS"
>+
>+rm -rf /tmp/etc
>+/sbin/umount /tmp
>+
>+
>+# Allow for override files to replace files in /etc. Use /conf/*/etc
>+# to find the override files. First choice is default files that
>+# always override, then files that from the directory that matches the
>+# client's broadcast address, finally followed by overrides that match
>+# the client's IP address.
>+#
> # This way we have some flexibility to handle clusters of machines
> # on separate subnets.
> #
>-# WARNING! null mounts cannot handle mmap, and since many programs
>-# use mmap (such as 'cp'), we have to copy.
>-#
>-mount_mfs -s 2048 -T qp120at dummy /conf/etc
>-cp -Rp /etc/* /conf/etc
>-chkerr $? "MFS mount on /conf/etc"
>
>-# Pick up default, network-specific, and host-specific config, in that
>-# order
>-
> if [ -d /conf/default/etc/ ]; then
>- cp -Rp /conf/default/etc/* /conf/etc
>+ cp -Rp /conf/default/etc/* /etc
> fi
>
> if [ -d /conf/${bootp_ipbca} ] ; then
>- cp -Rp /conf/${bootp_ipbca}/etc/* /conf/etc
>+ cp -Rp /conf/${bootp_ipbca}/etc/* /etc
> fi
>
> if [ -d /conf/${bootp_ipa} ] ; then
>- cp -Rp /conf/${bootp_ipa}/etc/* /conf/etc
>+ cp -Rp /conf/${bootp_ipa}/etc/* /etc
> fi
>-
>-# Make the new directory available as /etc
>-#
>-mount_null /conf/etc /etc
>
> # Tell /etc/rc to run the specified script after
> # it does its mounts but before it does anything
Sven Huster
Senior IT Systems Administrator
*BSD, Linux, Solaris
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