Re: [PATCH v20 00/12] Implement copy offload support

[Christoph Hellwig]

On Mon, May 20, 2024 at 03:50:13PM +0530, Nitesh Shetty wrote:
> So copy offload works only for request based storage drivers.

I don't think that is actually true.  It just requires a fair amount of
code in a bio based driver to match the bios up.

I'm missing any kind of information on what this patch set as-is
actually helps with.  What operations are sped up, for what operations
does it reduce resource usage?

Part of that might be that the included use case of offloading
copy_file_range doesn't seem particularly useful - on any advance
file system that would be done using reflinks anyway.

Have you considered hooking into dm-kcopyd which would be an
instant win instead?  Or into garbage collection in zoned or other
log structured file systems?  Those would probably really like
multiple source bios, though.