Re: [PATCH v20 02/12] Add infrastructure for copy offload in block and request layer.

Bart Van Assche
2024-06-25T18:19:16Z

On 6/24/24 2:55 PM, Damien Le Moal wrote:
> I am still a little confused as to why we need 2 BIOs, one for src and one for
> dst... Is it because of the overly complex scsi extended copy support ?
>
> Given that the main use case is copy offload for data within the same device,
> using a single BIO which somehow can carry a list of LBA sources and a single
> destination LBA would be far simpler and perfectly matching nvme simple copy and
> ATA write gathered. And I think that this would also match the simplest case for
> scsi extended copy as well.

Hi Damien,

What are the implications for the device mapper code if the copy source
and destination LBAs are encoded in the bio payload instead of in
bio->bi_sector?

Thanks,

Bart.