Re: [PATCH 1/3] libxfs: don't set mp->m_rtdev_targp when no RT devices is provided

[Christoph Hellwig <hch@lst.de>]

On Fri, Sep 11, 2026 at 07:57:26AM -0700, Darrick J. Wong wrote:
> > -	if (!xi->rt.dev || xi->rt.dev == xi->data.dev)
> > +	if (xi->rt.dev == xi->data.dev)
> >  		mp->m_rtdev_targp = mp->m_ddev_targp;
> >  	else
> >  		mp->m_rtdev_targp = libxfs_buftarg_alloc(mp, xi, &xi->rt,
> 
> Does this mean that m_rtdev_targp is never NULL, even when we don't
> specify or have a rt device attached?

I think that is the case right now.

> I would have expected this to be:
> 
> 	if (!xi->rt.dev)
> 		mp->m_rtdev_targp = NULL;
> 	else if (xi->rt.dev == xi->data.dev)
> 		mp->m_rtdev_targp = mp->m_ddev_targp;
> 	else
> 		mp->m_rtdev_targp = libxfs_buftarg_alloc(...);

And that is what we get with this patch.  The zeroing is done by
zeroing the entire mount structure in the callers of libxfs_mount
(don't ask me why..).