[dm-devel] [RFC PATCH 1/3] block: add copy offload support

[Keith Busch]

On Thu, Feb 03, 2022 at 01:50:06PM -0500, Mikulas Patocka wrote:
> On Tue, 1 Feb 2022, Bart Van Assche wrote:
> > Only supporting copying between contiguous LBA ranges seems restrictive to me.
> > I expect garbage collection by filesystems for UFS devices to perform better
> > if multiple LBA ranges are submitted as a single SCSI XCOPY command.
> 
> NVMe has a possibility to copy multiple source ranges into one destination 
> range. But I think that leveraging this capability would just make the 
> code excessively complex.

The point is to defrag discontiguous blocks into a single range. The
capability loses a major value proposition without multiple sources.