Re: [PATCHv5 08/11] nvme: map uring_cmd data even if address is 0

[Ming Lei <ming.lei@redhat.com>]

On Mon, Feb 24, 2025 at 01:31:13PM -0800, Keith Busch wrote:
> From: Xinyu Zhang <xizhang@purestorage.com>
> 
> 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.
> We can skip checking whether the address is NULL before mapping
> uring_cmd data. Bad userspace address will be handled properly later when
> the user buffer is imported.
> With this patch, we will be able to use the kernel registered bvec fixed
> buffers in io_uring NVMe passthru with ublk zero-copy support in
> https://lore.kernel.org/io-uring/20250218224229.837848-1-kbusch@meta.com/T/#u.
> 
> Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
> Reviewed-by: Jens Axboe <axboe@kernel.dk>
> Reviewed-by: Keith Busch <kbusch@kernel.org>
> Signed-off-by: Xinyu Zhang <xizhang@purestorage.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming