Re: [RFC PATCH] xfs: use log_incompat feature instead of speculate matching

Gao Xiang
2020-08-24T15:43:18Z

On Mon, Aug 24, 2020 at 08:08:32AM -0700, Darrick J. Wong wrote:
> On Mon, Aug 24, 2020 at 04:34:02PM +0800, Gao Xiang wrote:
> > On Mon, Aug 24, 2020 at 04:19:00PM +0800, Gao Xiang wrote:
> > > From: Gao Xiang <hsiangkao@redhat.com>
> > >
> > > Use a log_incompat feature just to be safe.
> > > If the current mount is in RO state, it will defer
> > > to next RW remount.
> > >
> > > Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
> > > ---
> > >
> > > After some careful thinking, I think it's probably not working for
> > > supported V4 XFS filesystem. So, I think we'd probably insist on the
> > > previous way (correct me if I'm wrong)...
> > >
> > > (since xfs_sb_to_disk() refuses to set up any feature bits for non V5
> > > fses. That is another awkward setting here (doesn't write out/check
> > > feature bits for V4 even though using V4 sb reserved fields) and
> > > unless let V4 completely RO since this commit. )
> > >
> > > Just send out as a RFC patch. Not fully tested after I thought as above.
> >
> > Unless we also use sb_features2 for V4 filesystem to entirely
> > refuse to mount such V4 filesystem...
> > Some more opinions on this?
>
> Frankly, V4 is pretty old, so I wouldn't bother. We only build new
> features for V5 format.

Okay, let me go further with log_incompat (v5) and sb_features2 (v4)
later.

Thanks,
Gao Xiang

>
> --D
>
> > Thanks,
> > Gao Xiang
> >
>