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Date:   Wed, 28 Jul 2021 02:16:21 +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 05/11] VFS: new function: mount_is_internal()
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 <162742546552.32498.14429836898036234922.stgit@noble.brown>
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On Wed, Jul 28, 2021 at 08:37:45AM +1000, NeilBrown wrote:
> This patch introduces the concept of an "internal" mount which is a
> mount where a filesystem has create the mount itself.
> 
> Both the mounted-on-dentry and the mount's root dentry must refer to the
> same superblock (they may be the same dentry), and the mounted-on dentry
> must be an automount.

And what happens if you mount --move it?