samba - Feb 2023 - Missing Files/Missing Folders from an NFS Share

On Mon, Feb 27, 2023 at 01:18:20PM +0100, Conor Armstrong via samba
wrote:
>Just by way of update on this, it looks like the problem exists with the
>ReadDir, TellDir and SeekDir implementation on NFS shares.  In my case it
>was an AWS EFS share that uses NFS.
Can you elaborate exactly the issue with the AWS NFS server here ?
It would be really helpful to understand what it's doing here.
>The fix in the samba code isn't straightforward.  As a workaround on my
>case I discovered that if I mount the NFS share at say /mnt/mountpoint1 and
>the use sshfs to connect back into the same machine and mount at
>/mnt/mountpoint2 the /mnt/mountpoint1 directory I can then share the
>/mnt/mountpoint2 share with Samba and the sshfs layer that sits between
>Samba and the NFS mount seems to correct the issues that are present if t
>the mounted NFS share were shared with Samba directly.
>
>So instead of
>
>NFS -> /mnt/mountpoint1 and /mnt/mountpoint1 -> Samba -> Windows
Client
>
>I use
>
>NFS -> /mnt/mountpoint1 and /mnt/mountpoint1 -> /mnt/mountpoint2 (via
>sshfs) and /mnt/mountpoint2 -> Samba -> Windows Client
>
>There is a performance hit in doing this, but it is something I can live
>with.
I'm glad you found a fix, but if we can understand what is wrong
with AWS NFS here we might be able to do something more performant
in Samba.

I think it has a lot to do with telldir on an NFS share returning a cookie
that is supposed to be unique rather than an actual offset. Problem is,
that cookie is stored as a 31bit hash which can then end up as a negative
signed offset in Samba which is not handled correctly. The cookies are not
necessarily consecutive as you move through a directory.

On Mon, 27 Feb 2023 at 19:00, Jeremy Allison <jra at samba.org> wrote:
> On Mon, Feb 27, 2023 at 01:18:20PM +0100, Conor Armstrong via samba wrote:
> >Just by way of update on this, it looks like the problem exists with
the
> >ReadDir, TellDir and SeekDir implementation on NFS shares.  In my case
it
> >was an AWS EFS share that uses NFS.
>
> Can you elaborate exactly the issue with the AWS NFS server here ?
> It would be really helpful to understand what it's doing here.
>
> >The fix in the samba code isn't straightforward.  As a workaround
on my
> >case I discovered that if I mount the NFS share at say /mnt/mountpoint1
> and
> >the use sshfs to connect back into the same machine and mount at
> >/mnt/mountpoint2 the /mnt/mountpoint1 directory I can then share the
> >/mnt/mountpoint2 share with Samba and the sshfs layer that sits between
> >Samba and the NFS mount seems to correct the issues that are present if
t
> >the mounted NFS share were shared with Samba directly.
> >
> >So instead of
> >
> >NFS -> /mnt/mountpoint1 and /mnt/mountpoint1 -> Samba ->
Windows Client
> >
> >I use
> >
> >NFS -> /mnt/mountpoint1 and /mnt/mountpoint1 -> /mnt/mountpoint2
(via
> >sshfs) and /mnt/mountpoint2 -> Samba -> Windows Client
> >
> >There is a performance hit in doing this, but it is something I can
live
> >with.
>
> I'm glad you found a fix, but if we can understand what is wrong
> with AWS NFS here we might be able to do something more performant
> in Samba.
>