Re: [PATCH 1/5] block: new sector copy api

Christoph Hellwig
2025-05-23T13:01:39Z

On Wed, May 21, 2025 at 03:31:03PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
>
> Provide a basic block level api to copy a range of a block device's
> sectors to a new destination on the same device. This just reads the
> source data into host memory, then writes it back out to the device at
> the requested destination.

As someone who recently spent a lot of time on optimizing such loops:
having a general API that allocates a buffer for each copy is a bad
idea. You'll want some kind of caller provided longer living allocation
if you do regularly do such copies.

Maybe having common code is good to avoid copies, but I suspect most
real users would want their own.