Messages in this thread | | | Date | Thu, 27 Feb 2003 09:25:45 +0100 | From | Kasper Dupont <> | Subject | Re: About /etc/mtab and /proc/mounts |
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Miles Bader wrote: > > Kasper Dupont <kasperd@daimi.au.dk> writes: > > > /var is clearly the right place for this; > > > > Is it? > > Yes. On some systems, /var and /tmp are the _only_ read-write filesystems.
OK, but then on such a system with my approach it would be possible to make /mtab.d a symlink pointing to somewhere under /var.
> > > > if /var isn't mounted initially, I'd suggest that mount should > > > simply not update any file at that point, and the init-script that > > > mounts /var can be responsible from propagating information from > > > /proc/mounts to /var/whatever. > > > > Would you fsck /var while it is mounted? > > No, of course not; that's why I suggest it's up to the init scripts to > make sure that /proc/mounts gets propagated to /var/whatever. They > usually will know enough about what's going on to take care of any > special cases and add any extra info that's relevant.
But AFAIK fsck uses mtab.
> > If a program such as `mount' wants to use mtab and finds that it's not > present (possibly because /var isn't mounted), it should either use > /proc/mounts instead, or just ignore it.
If mtab does not exist mount will attempt to create a new one with only the root listed.
> > > I think part of the problem is that /var is used for both files > > we want to keep across reboot, and files we do not want to keep > > across reboot. > > [/var/run is for `non-persistant' files]
But that doesn't solve the problem with ordering. If we don't want to change a lot of userspace utilities and the order in which things are done during boot, we need /var/run mounted earlier than /var. And /var/run is not the only directory with files we do not want to keep across boot. There are some in /var/lock too, and AFAIR a few other locations.
> > > There are cases where it is undesirable to have mtab in /var, > > but if mount expect to find mtab somewhere under /var, we can't > > even use a symlink to get it out of there, because /var needs > > to be mounted before the symlink can be followed. > > It will simply appear to mount as if the file isn't present, in which > case it should gracefully stop trying to use it [see above]. > > It seems like the attempt here is to somehow make everything just work > magically _without_ modifying any tools that use mtab -- and I think > that just isn't doable in every situation.
Maybe not, but I certainly don't want to change every program that reads mtab. If we can limit the changes to those tools that needs to write mtab, it might be feasible.
-- Kasper Dupont -- der bruger for meget tid på usenet. For sending spam use mailto:aaarep@daimi.au.dk for(_=52;_;(_%5)||(_/=5),(_%5)&&(_-=2))putchar(_); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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