NVMe write protection support

[Christoph Hellwig]

On Fri, Sep 30, 2022 at 07:49:38PM +0200, Gilles BULOZ wrote:
> Hi Christoph,
> Our disk manufacturer told me their NVMe does not follow NVMe specification 2.0 but 1.3.
> Is there also something in 1.3 to handle the write protection cleanly ?

NVMe 1.3 has not write protection feature.  That being NVMe is designed
so that new functionality (new TPs in NVMe terms) can be implemented by
devices that comply to older versions.  So if you just set the bit as
described earlier Linux (and other drivers that know about the feature)
will still do the right thing even if the compliance level is left as
NVM 1.3.