On Wed, Jun 17, 2020 at 12:14:28PM -0500, Eric Sandeen wrote: > > > 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@xxxxxxxxxxxxxx> > >>> > >>> /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' Yeah, because the mount option is 'iversion', not 'i_version'. Even if you were going to expose the flag state in /proc/mounts, the text string should match the mount option. > 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 Probably because do_mount clears it and I guess xfs don't re-enable it in any of their remount functions... --D > -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. > >
