On Fri, Jun 19, 2020 at 08:39:48AM +1000, Dave Chinner wrote: > On Wed, Jun 17, 2020 at 11:45:35PM -0400, Masayoshi Mizuma wrote: > > Thank you for pointed it out. > > How about following change? I believe it works both xfs and btrfs... > > > > diff --git a/fs/super.c b/fs/super.c > > index b0a511bef4a0..42fc6334d384 100644 > > --- a/fs/super.c > > +++ b/fs/super.c > > @@ -973,6 +973,9 @@ int reconfigure_super(struct fs_context *fc) > > } > > } > > > > + if (sb->s_flags & SB_I_VERSION) > > + fc->sb_flags |= MS_I_VERSION; > > + > > WRITE_ONCE(sb->s_flags, ((sb->s_flags & ~fc->sb_flags_mask) | > > (fc->sb_flags & fc->sb_flags_mask))); > > /* Needs to be ordered wrt mnt_is_readonly() */ > > This will prevent SB_I_VERSION from being turned off at all. That > will break existing filesystems that allow SB_I_VERSION to be turned > off on remount, such as ext4. > > The manipulations here need to be in the filesystem specific code; > we screwed this one up so badly there is no "one size fits all" > behaviour that we can implement in the generic code... My memory was that after Jeff Layton's i_version patches, there wasn't really a significant performance hit any more, so the ability to turn it off is no longer useful. But looking back through Jeff's postings, I don't see him claiming that; e.g. in: https://lore.kernel.org/lkml/20171222120556.7435-1-jlayton@xxxxxxxxxx/ https://lore.kernel.org/linux-nfs/20180109141059.25929-1-jlayton@xxxxxxxxxx/ https://lore.kernel.org/linux-nfs/1517228795.5965.24.camel@xxxxxxxxxx/ he reports comparing old iversion behavior to new iversion behavior, but not new iversion behavior to new noiversion behavior. --b.
