Re: [PATCH v6 5/9] Documentation: add a new file documenting multigrain timestamps

Jeff Layton
2024-07-17T12:02:26Z

On Wed, 2024-07-17 at 13:31 +0200, Jan Kara wrote:
> On Mon 15-07-24 08:48:56, Jeff Layton wrote:
> > Add a high-level document that describes how multigrain timestamps work,
> > rationale for them, and some info about implementation and tradeoffs.
> >
> > Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> > Signed-off-by: Jeff Layton <jlayton@kernel.org>
>
> One comment below. With that fixed feel free to add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
>
> > +Implementation Notes
> > +====================
> > +Multigrain timestamps are intended for use by local filesystems that get
> > +ctime values from the local clock. This is in contrast to network filesystems
> > +and the like that just mirror timestamp values from a server.
> > +
> > +For most filesystems, it's sufficient to just set the FS_MGTIME flag in the
> > +fstype->fs_flags in order to opt-in, providing the ctime is only ever set via
> > +inode_set_ctime_current(). If the filesystem has a ->getattr routine that
> > +doesn't call generic_fillattr, then you should have it call fill_mg_cmtime to
> > +fill those values.
>
> I think you should explicitely mention that ->setattr() implementation
> needs to use setattr_copy() or otherwise mimic its behavior...
>
> Honza

I've added a sentence like you suggest to the patch in my tree. Thanks
for all the reviews!
--
Jeff Layton <jlayton@kernel.org>