Re: udev and devfs - The final word

[Andreas Dilger]

On Dec 31, 2003  22:55 +0000, viro@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx wrote:
> 	h) nfsd uses device number as a substitute for export ID if said
> ID is not given explicitly.  That, BTW, is a big problem for crackpipe
> dreams about random device numbers - export ID _must_ be stable across
> reboots.

We had a problem with this and Lustre, when we NFS export it.  Lustre is
already a network filesystem so we don't have a device number.  I had a
discussion with Neil Brown about this and suggested that we allow NFS to
get a _real_ stable export ID from the filesystem (e.g. superblock UUID
or similar) instead of the device number hackery which only has a vague
relationship to stable.

We implemented it for Lustre with a filesystem option FS_NFSEXP_FSID
that tells nfsd it can export such a filesystem in the absence of
FS_REQUIRES_DEV and then put our export ID into sb->s_dev (although I'd
prefer something slightly cleaner than that).

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/