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Date:   Wed, 17 Jun 2020 14:45:07 -0400
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Eric Sandeen <sandeen@sandeen.net>
Cc:     "Darrick J. Wong" <darrick.wong@oracle.com>,
        Christoph Hellwig <hch@infradead.org>,
        Masayoshi Mizuma <msys.mizuma@gmail.com>,
        Theodore Ts'o <tytso@mit.edu>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>,
        linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH] fs: i_version mntopt gets visible through /proc/mounts
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On Wed, Jun 17, 2020 at 01:28:11PM -0500, Eric Sandeen wrote:
> but mount(8) has already exposed this interface:
> 
>        iversion
>               Every time the inode is modified, the i_version field will be incremented.
> 
>        noiversion
>               Do not increment the i_version inode field.
> 
> so now what?

It's not like anyone's actually depending on i_version *not* being
incremented.  (Can you even observe it from userspace other than over
NFS?)

So, just silently turn on the "iversion" behavior and ignore noiversion,
and I doubt you're going to break any real application.

--b.