On Tue, 27 Mar 2001, Dan Hollis wrote:
> On Tue, 27 Mar 2001, H. Peter Anvin wrote:
> > c) Make sure chown/chmod/link/symlink/rename/rm etc does the right thing,
> > without the need for "tar hacks" or anything equivalently gross.
>
> write-through filesystem, like overlaying a r/w ext2 on top of an iso9660
> fs.
functionality to do this is in devfs and devfsd already.
there are 2 ways:
1. devfs on /dev, maintain state in /dev-state.
2. regular ext2 (devfs naming style) /dev and devfs mounted on, eg,
/devfs for hotplug and module load/unload updates
1:
/dev-state -> regular ext2
/dev -> devfs
use the CREATE, CHANGE and REGISTER hooks that devfs has to
allow devfsd to transparently copy changes in /dev to the ext2
/dev-state. See the example devfsd.conf for appropriate entries, eg:
REGISTER .* COPY /dev-state/$devname $devpath
CHANGE .* COPY $devpath /dev-state/$devname
CREATE .* COPY $devpath /dev-state/$devname
2:
/dev -> regular ext2
/devfs -> devfs
use the devfs hooks for REGISTER and UNREGISTER to have devfsd update
the static /dev whenever hotplug events occur. Eg:
REGISTER .* COPY ${mntpnt}/$devname /dev/$devname
UNREGISTER .* CFUNCTION GLOBAL unlink /dev/$devname
seems to work for me:
[root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram
ls: /dev/misc/nvram: No such file or directory
ls: /devfs/misc/nvram: No such file or directory
[root@fogarty /devfs]# modprobe nvram
[root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram
crw-r----- 1 root root 10, 144 Jan 1 1970 /devfs/misc/nvram
crw-r----- 1 root root 10, 144 Mar 28 01:56 /dev/misc/nvram
[root@fogarty /devfs]# rmmod nvram
[root@fogarty /devfs]# ls -l /dev{,fs}/misc/nvram
ls: /dev/misc/nvram: No such file or directory
ls: /devfs/misc/nvram: No such file or directory
> -Dan
i prefer option 2 as /dev state is then not dependent on devfsd being
there and it just sidesteps the whole permissions issue. if devfsd
doesn't start then i still have a fully functional /dev.
but anyway... there seems to be loads of scope to do lots of
different things with devfsd, plus NIS support. :)
regards,
-- Paul Jakma paul@clubi.ie paul@jakma.org PGP5 key: http://www.clubi.ie/jakma/publickey.txt ------------------------------------------- Fortune: Premature optimization is the root of all evil. -- D.E. Knuth- 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/
This archive was generated by hypermail 2b29 : Sat Mar 31 2001 - 21:00:17 EST