Re: [PATCH v2 1/3] fs: add infrastructure for multigrain inode i_m/ctime

Jeff Layton
2023-04-25T17:45:26Z

On Tue, 2023-04-25 at 08:40 +1000, NeilBrown wrote:
> On Tue, 25 Apr 2023, Jeff Layton wrote:
> > On Tue, 2023-04-25 at 07:47 +1000, NeilBrown wrote:
> > > On Tue, 25 Apr 2023, Jeff Layton wrote:
> > > > + /*
> > > > + * Warn if someone sets SB_MULTIGRAIN_TS, but doesn't turn down the ts
> > > > + * granularity.
> > > > + */
> > > > + return (sb->s_flags & SB_MULTIGRAIN_TS) &&
> > > > + !WARN_ON_ONCE(sb->s_time_gran == 1);
> > >
> > > Maybe
> > > !WARN_ON_ONCE(sb->s_time_gran & SB_MULTIGRAIN_TS);
> > > ??
> > >
> >
> > I'm not sure I understand what you mean here.
>
> That's fair, as what I wrote didn't make any sense.
> I meant to write:
>
> !WARN_ON_ONCE(sb->s_time_gran & I_CTIME_QUERIED);
>
> to make it explicit that s_time_gran must leave space for
> I_CTIME_QUERIED to be set (as you write below). Specifically that
> s_time_gran mustn't be odd.
>

Erm...it may be an unpopular opinion, but I find that more confusing
than just ensuring that the s_time_gran > 1. I keep wondering if we
might want to carve out other low-order bits too for some later purpose,
at which point trying to check this using flags wouldn't work right. I
think I might just stick with what I have here, at least for now.

--
Jeff Layton <jlayton@kernel.org>