Re: file handle in statx (was: Re: How to cope with subvolumes and snapshots on muti-user systems?)

David Howells
2023-12-12T09:10:55Z

Christian Brauner <brauner@kernel.org> wrote:

> > > > I suggest:
> > > >
> > > > STATX_ATTR_INUM_NOT_UNIQUE - it is possible that two files have the
> > > > same inode number
>
> This is just ugly with questionable value. A constant reminder of how
> broken this is. Exposing the subvolume id also makes this somewhat redundant.

There is a upcoming potential problem where even the 64-bit field I placed in
statx() may be insufficient. The Auristor AFS server, for example, has a
96-bit vnode ID, but I can't properly represent this in stx_ino. Currently, I
just truncate the value to fit and hope that the discarded part will be all
zero, but that's not really a good thing to do - especially when stx_ino is
used programmatically to check for hardlinks.

Would it be better to add an 'stx_ino_2' field and corresponding flag?

David