Re: [PATCH] nvme: map uring_cmd data even if address is 0

[Christoph Hellwig]

On Mon, Feb 24, 2025 at 07:54:59AM -0700, Keith Busch wrote:
> On Mon, Feb 24, 2025 at 03:33:51PM +0100, Christoph Hellwig wrote:
> > On Thu, Feb 20, 2025 at 04:51:01PM -0700, Xinyu Zhang wrote:
> > > When using kernel registered bvec fixed buffers, the "address" is
> > > actually the offset into the bvec rather than userspace address.
> > > Therefore it can be 0.
> > 
> > How is that actually going to work?  Who is interpreting that address?
> 
> io_import_fixed() treats the address as an offset into its bio_vec.

Ah, yes.  This is in nvme_uring_data and read from the SQE.  I thought
we were further down.