Re: [PATCH v2] xfs: zero newly allocated btree root space

[Darrick J. Wong]

On Thu, Jul 02, 2026 at 04:05:06AM -0700, Christoph Hellwig wrote:
> On Wed, Jul 01, 2026 at 08:52:34AM -0700, Darrick J. Wong wrote:
> > > This almost sounds like we should explicitly zero this case just for that
> > > particular case.  Although Darrick was kinda heading in a different
> > > direction and I don't want to start a fight here.
> > 
> > I'm fine with either solution; I simply prefer the one that fixes all
> > the current and future "oops we forgot to zero a hidden padding" bugs in
> > one action.
> 
> Maybe we should avoid creating hidden zero padding to start with? :)
> But this is a small allocation, and most of it gets overwritten
> while the cache is still hot, so I can live with the unconditional
> zeroing.  Still feels a bit odd to reach for the big hammer.

<shrug> If this is truly the only place where we forget to initialize
if_broot fully then I'm ok with just doing that and not going for
GFP_ZERO.  If we have an army of KASAN syzbotters whacking away at the
system, then I could reevaluate my resistance to whack-a-mole.

--D