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Date:   Wed, 28 Jul 2021 02:19:22 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     NeilBrown <neilb@suse.de>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Josef Bacik <josef@toxicpanda.com>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Chuck Lever <chuck.lever@oracle.com>, Chris Mason <clm@fb.com>,
        David Sterba <dsterba@suse.com>, linux-fsdevel@vger.kernel.org,
        linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH/RFC 00/11] expose btrfs subvols in mount table correctly
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On Wed, Jul 28, 2021 at 08:37:45AM +1000, NeilBrown wrote:

> We can enhance nfsd to understand that some automounts can be managed.
> "internal mounts" where a filesystem provides an automount point and
> mounts its own directories, can be handled differently by nfsd.
> 
> This series addresses all these issues.  After a few enhancements to the
> VFS to provide needed support, they enhance exportfs and nfsd to cope
> with the concept of internal mounts, and then enhance btrfs to provide
> them.

I'm half asleep right now; will review and reply in detail tomorrow.
The first impression is that it's going to be brittle; properties of
mount really should not depend upon the nature of mountpoint - too many
ways for that to go wrong.

Anyway, tomorrow...