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Date:   Thu, 15 Jul 2021 18:24:33 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Josef Bacik <josef@toxicpanda.com>
Cc:     Christoph Hellwig <hch@infradead.org>, NeilBrown <neilb@suse.de>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        Chuck Lever <chuck.lever@oracle.com>, Chris Mason <clm@fb.com>,
        David Sterba <dsterba@suse.com>, linux-nfs@vger.kernel.org,
        Wang Yugui <wangyugui@e16-tech.com>,
        Ulli Horlacher <framstag@rus.uni-stuttgart.de>,
        linux-btrfs@vger.kernel.org
Subject: Re: [PATCH/RFC] NFSD: handle BTRFS subvolumes better.
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On Thu, Jul 15, 2021 at 01:11:29PM -0400, Josef Bacik wrote:
> Because there's no alternative.  We need a way to tell userspace they've
> wandered into a different inode namespace.  There's no argument that what
> we're doing is ugly, but there's never been a clear "do X instead".  Just a
> lot of whinging that btrfs is broken.  This makes userspace happy and is
> simple and straightforward.  I'm open to alternatives, but there have been 0
> workable alternatives proposed in the last decade of complaining about it.

Make sure we cross a vfsmount when crossing the "st_dev" domain so
that it is properly reported.   Suggested many times and ignored all
the time beause it requires a bit of work.