From: Eric Sandeen <sandeen@sandeen.net>
To: "J. Bruce Fields" <bfields@fieldses.org>,
Christoph Hellwig <hch@infradead.org>
Cc: 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
Date: Wed, 17 Jun 2020 12:14:28 -0500 [thread overview]
Message-ID: <24692989-2ee0-3dcc-16d8-aa436114f5fb@sandeen.net> (raw)
In-Reply-To: <20200617155836.GD13815@fieldses.org>
On 6/17/20 10:58 AM, J. Bruce Fields wrote:
> On Wed, Jun 17, 2020 at 01:03:14AM -0700, Christoph Hellwig wrote:
>> On Tue, Jun 16, 2020 at 04:21:23PM -0400, Masayoshi Mizuma wrote:
>>> From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
>>>
>>> /proc/mounts doesn't show 'i_version' even if iversion
>>> mount option is set to XFS.
>>>
>>> iversion mount option is a VFS option, not ext4 specific option.
>>> Move the handler to show_sb_opts() so that /proc/mounts can show
>>> 'i_version' on not only ext4 but also the other filesystem.
>>
>> SB_I_VERSION is a kernel internal flag. XFS doesn't have an i_version
>> mount option.
>
> It probably *should* be a kernel internal flag, but it seems to work as
> a mount option too.
Not on XFS AFAICT:
[600280.685810] xfs: Unknown parameter 'i_version'
so we can't be exporting "mount options" for xfs that aren't actually
going to be accepted by the filesystem.
> By coincidence I've just been looking at a bug report showing that
> i_version support is getting accidentally turned off on XFS whenever
> userspace does a read-write remount.
>
> Is there someplace in the xfs mount code where it should be throwing out
> SB_I_VERSION?
<cc xfs list>
XFS doesn't manipulate that flag on remount. We just turn it on by default
for modern filesystem formats:
/* version 5 superblocks support inode version counters. */
if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
sb->s_flags |= SB_I_VERSION;
Also, this behavior doesn't seem unique to xfs:
# mount -o loop,i_version fsfile test_iversion
# grep test_iversion /proc/mounts
/dev/loop4 /tmp/test_iversion ext4 rw,seclabel,relatime,i_version 0 0
# mount -o remount test_iversion
# grep test_iversion /proc/mounts
/dev/loop4 /tmp/test_iversion ext4 rw,seclabel,relatime 0 0
# uname -a
Linux <hostname> 5.7.0-rc4+ #7 SMP Wed Jun 10 14:01:34 EDT 2020 x86_64 x86_64 x86_64 GNU/Linux
-Eric
> Ideally there'd be entirely different fields for mount options and
> internal feature flags. But I don't know, maybe SB_I_VERSION is the
> only flag we have like this.
>
> --b.
>
next prev parent reply other threads:[~2020-06-17 17:14 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 20:21 [PATCH] fs: i_version mntopt gets visible through /proc/mounts Masayoshi Mizuma
2020-06-17 8:03 ` Christoph Hellwig
2020-06-17 13:33 ` Masayoshi Mizuma
2020-06-17 15:58 ` J. Bruce Fields
2020-06-17 17:14 ` Eric Sandeen [this message]
2020-06-17 17:24 ` Darrick J. Wong
2020-06-17 17:55 ` Eric Sandeen
2020-06-17 18:18 ` J. Bruce Fields
2020-06-17 18:28 ` Eric Sandeen
2020-06-17 18:45 ` J. Bruce Fields
2020-06-18 1:30 ` Masayoshi Mizuma
2020-06-18 1:44 ` Darrick J. Wong
2020-06-18 3:33 ` Masayoshi Mizuma
2020-06-18 3:05 ` Dave Chinner
2020-06-18 3:45 ` Masayoshi Mizuma
2020-06-18 22:39 ` Dave Chinner
2020-06-19 2:20 ` J. Bruce Fields
2020-06-19 2:44 ` Dave Chinner
2020-06-19 12:04 ` Jeff Layton
2020-06-19 20:40 ` J. Bruce Fields
2020-06-19 22:10 ` Dave Chinner
2020-06-19 22:28 ` J. Bruce Fields
2020-06-20 1:49 ` Dave Chinner
2020-06-20 1:56 ` J. Bruce Fields
2020-06-20 17:00 ` Eric Sandeen
2020-06-20 17:09 ` J. Bruce Fields
2020-06-20 23:54 ` Dave Chinner
2020-06-22 21:26 ` J. Bruce Fields
2020-06-22 22:03 ` Dave Chinner
2020-06-19 13:17 ` Christoph Hellwig
2020-07-13 23:45 ` Eric Sandeen
2020-07-14 8:30 ` Christoph Hellwig
2020-07-14 20:26 ` Eric Sandeen
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