[PATCH v3 04/10] block: introduce dma map backed bio type

[Christoph Hellwig]

On Mon, May 18, 2026 at 11:29:54AM +0100, Pavel Begunkov wrote:
>>>   	BIO_ZONE_WRITE_PLUGGING, /* bio handled through zone write plugging */
>>>   	BIO_EMULATES_ZONE_APPEND, /* bio emulates a zone append operation */
>>> +	BIO_DMABUF_MAP, /* Using premmaped dma buffers */
>>
>> Shouldn't this be a REQ_ flag as we should never mix and match bios with
>> and without this flag in a single request?
>
> Do you mean adding both and propagating it from bio to req? submit_bio()
> takes a bio, so we still need to set it there before it reaches blk-mq.
> And there might be bio-based drivers using it in the future.

I think I forgot to reply to this, so let's do this now.

REQ_ is actually used by both bios and requests, so if you set it in
bio->bi_opf it will automatically get propagated to the request, but
it can also always be tested on the bio, including by bio-based
drivers.