Re: [dm-devel] [PATCH v14 00/11] Implement copy offload support

[Bart Van Assche]

On 8/11/23 03:52, Nitesh Shetty wrote:
> We achieve copy offload by sending 2 bio's with source and destination
> info and merge them to form a request. This request is sent to driver.
> So this design works only for request based storage drivers.

[ ... ]

> Overall series supports:
> ========================
> 	1. Driver
> 		- NVMe Copy command (single NS, TP 4065), including support
> 		in nvme-target (for block and file back end).
>
> 	2. Block layer
> 		- Block-generic copy (REQ_OP_COPY_DST/SRC), operation with
>                    interface accommodating two block-devs
>                  - Merging copy requests in request layer
> 		- Emulation, for in-kernel user when offload is natively
>                  absent
> 		- dm-linear support (for cases not requiring split)
>
> 	3. User-interface
> 		- copy_file_range

Is this sufficient? The combination of dm-crypt, dm-linear and the NVMe 
driver is very common. What is the plan for supporting dm-crypt? 
Shouldn't bio splitting be supported for dm-linear?

Thanks,

Bart.