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To:     "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
From:   Alkis Georgopoulos <alkisg@gmail.com>
Subject: bindfs over NFS shows the underlying file system
Message-ID: <ae761918-245e-e25c-7aab-dd465f7c2461@gmail.com>
Date:   Fri, 11 Oct 2019 08:24:14 +0300
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I'm not sure if this is an NFS issue, or a bindfs issue, or if I'm not 
using the appropriate NFS options.

I export my /home via NFS with:

     /home *(rw,async,crossmnt,no_subtree_check,no_root_squash,insecure)

Inside my /home I'm providing a shared folder with a bindfs mount:

     bindfs -u 1000 --create-for-user=1000 -g 100 --create-for-group=100 
-p 770,af-x /home/share /home/share

I.e. this just sets fixed permissions for anything under /home/share.

And finally I mount /home on some NFS client (or on localhost):

     mount -t nfs server:/home /home

The problem is that /home/share on the client doesn't show the bindfs 
permissions, but it shows the underlying file system of the server's 
/home/share.
The crossmnt NFS option follows submounts with other file systems, but 
not with bindfs.

On the other hand, if the bindfs source is on a different file system 
than the bindfs target directory, everything works fine (i.e. bindfs 
/other/filesystem/share /home/share).

Is there any way to configure either NFS or bindfs, so that this works 
when I only have one partition, i.e. when the share is on the same file 
system as /home?

If anyone answers, please Cc me as I'm not in the list.

Thank you very much,
Alkis Georgopoulos
LTSP developer