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Subject: Re: [PATCH] fs: i_version mntopt gets visible through /proc/mounts
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Dave Chinner <david@fromorbit.com>,
        Masayoshi Mizuma <msys.mizuma@gmail.com>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        "Darrick J. Wong" <darrick.wong@oracle.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>
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From:   Eric Sandeen <sandeen@sandeen.net>
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Message-ID: <e5aa3b59-63f4-b423-d7f2-59e506512626@sandeen.net>
Date:   Tue, 14 Jul 2020 13:26:17 -0700
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On 7/14/20 1:30 AM, Christoph Hellwig wrote:
> On Mon, Jul 13, 2020 at 04:45:19PM -0700, Eric Sandeen wrote:
>> I wandered back into this thread for some reason ... ;)
>>
>> Since iversion/noiversion is /already/ advertised as a vfs-level mount option,
>> wouldn't exposing it in /proc/mounts solve the original problem here?
>>
>> ("i_version" is wrong, because it's ext4-specific, but "iversion" is handled
>> by the vfs, so it's meaningful for any filesystems, and it will also trivially
>> allow mount(2) to preserve it across remounts for all filesystems that set it by
>> default.)
>>
>> Seems like that's the fastest path to fixing the current problems, even if a
>> long-term goal may be to deprecate it altogether.
> 
> But they should not be exposed as a mount option.  E.g. for XFS we
> decide internally if we have a useful i_version or not, totally
> independent of the mount option that leaked into the VFS.  So we'll
> need to fix how the flag is used before doing any new work in this area.
> 

It's been explicitly exposed, documented, fixed, updated etc for about
12 years now.

I was just hoping to make the current situation - even if we regret its
mere existence - less broken, because going down a deprecation path will
take us a while even if we choose it.

In the meantime I'll just make sure xfs isn't broken on remount, but had
hoped for a more general fix.  *shrug*

-Eric