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From:   Miklos Szeredi <miklos@szeredi.hu>
Date:   Fri, 6 Aug 2021 09:52:01 +0200
Message-ID: <CAJfpeguoMjCvLpKHgtQmNFk4UsHdyLsWK4bvsv6YJ52uZ=+9gg@mail.gmail.com>
Subject: Re: [PATCH 07/11] exportfs: Allow filehandle lookup to cross internal
 mount points.
To:     Amir Goldstein <amir73il@gmail.com>
Cc:     NeilBrown <neilb@suse.de>, 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>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Linux Btrfs <linux-btrfs@vger.kernel.org>
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On Thu, 29 Jul 2021 at 07:27, Amir Goldstein <amir73il@gmail.com> wrote:

> Given that today, subvolume mounts (or any mounts) on the lower layer
> are not followed by overlayfs, I don't really see the difference
> if mounts are created manually or automatically.
> Miklos?

Never tried overlay on btrfs.  Subvolumes AFAIK do not use submounts
currently, they are a sort of hack where the st_dev changes when
crossing the subvolume boundary, but there's no sign of them in
/proc/mounts (there's no d_automount in btrfs).

Thanks,
Miklos