Re: [LSF/MM/BPF TOPIC] Block storage copy offloading

[Keith Busch <kbusch@kernel.org>]

On Fri, Jan 23, 2026 at 02:19:44PM -0800, Bart Van Assche wrote:
> Adoption of zoned storage is increasing in mobile devices. Log-
> structured filesystems are better suited for zoned storage than
> traditional filesystems. These filesystems perform garbage collection.
> Garbage collection involves copying data on the storage medium.
> Offloading the copying operation to the storage device reduces energy
> consumption. Hence the proposal to discuss integration of copy
> offloading in the Linux kernel block, SCSI and NVMe layers.
> 
> Other use-cases for copy offloading include reducing network traffic in
> NVMeOF setups while copying data and also increasing throughput while
> copying data.

I'm interested in the topic. I'm just not sure about the approach. If it
doesn't support vectored sector sources, then it's much less
interesting. From the host point of view, I'd like to be able to submit
arbitrarily large bio's to the block layer that can be split and merged
for optimal alignment to hardware limits. The two-bio approach looks
overly complicated with respect to that.