Re: [LSF/MM/BFP ATTEND] [LSF/MM/BFP TOPIC] Storage: Copy Offload

[Bart Van Assche <bvanassche@acm.org>]

On 11/19/21 02:47, Kanchan Joshi wrote:
> Given the multitude of things accumulated on this topic, Martin
> suggested to have a table/matrix.
> Some of those should go in the initial patchset, and the remaining are
> to be staged for subsequent work.
> Here is the attempt to split the stuff into two buckets. Please change
> if something needs to be changed below.
> 
> 1. Driver
> *********
> Initial: NVMe Copy command (single NS)
> Subsequent: Multi NS copy, XCopy/Token-based Copy
> 
> 2. Block layer
> **************
> Initial:
> - Block-generic copy (REQ_OP_COPY), with interface accommodating two block-devs
> - Emulation, when offload is natively absent
> - DM support (at least dm-linear)
> 
> 3. User-interface
> *****************
> Initial: new ioctl or io_uring opcode
> 
> 4. In-kernel user
> ******************
> Initial: at least one user
> - dm-kcopyd user (e.g. dm-clone), or FS requiring GC (F2FS/Btrfs)
> 
> Subsequent:
> - copy_file_range

Integrity support and inline encryption support are missing from the above
overview. Both are supported by the block layer. See also block/blk-integrity.c
and include/linux/blk-crypto.h. I'm not claiming that these should be supported
in the first version but I think it would be good to add these to the above
overview.

Thanks,

Bart.