[OpenAFS-devel] New volume header field: root DV

[Jeffrey Hutzelman]

--On Tuesday, March 02, 2010 01:28:08 PM -0600 Andrew Deason 
<adeason@sinenomine.net> wrote:

> The purpose of this is for when we are salvaging a volume that has lost
> its root vnode. Gerrit 1235 has the code to create a new root vnode, but
> we must guess as to what the dv for it would be. The current guess is
> based on the creationDate for the volume, which isn't really robust.
>
> So instead, if we store the root dv redundantly in the volume header, we
> stand a much better chance at choosing a dv that won't screw up clients,
> since we can base the new dv off of the last known dv.

Yuck.  The root vnode DV is stored in the large vnode index, and in the 
metadata for the underlying inode (and, in namei, in the link table).  The 
only reason you'd need an additional copy is if you lost both the root 
vnode and the index, in which case it seems just as likely that you've lost 
the volume info inode as well.


> I don't think we're that cramped for header fields yet.

Which is exactly how we run out.

IMHO this seems excessive.