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From:   Andreas Hindborg <nmi@metaspace.dk>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        Keith Busch <kbusch@kernel.org>,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        Hannes Reinecke <hare@suse.de>,
        lsf-pc@lists.linux-foundation.org, rust-for-linux@vger.kernel.org,
        linux-block@vger.kernel.org, Matthew Wilcox <willy@infradead.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?utf-8?Q?Bj?= =?utf-8?Q?=C3=B6rn?= Roy Baron 
        <bjorn3_gh@protonmail.com>, Benno Lossin <benno.lossin@proton.me>,
        open list <linux-kernel@vger.kernel.org>, gost.dev@samsung.com
Subject: Re: [RFC PATCH 00/11] Rust null block driver
Date:   Thu, 04 May 2023 20:46:35 +0200
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Bart Van Assche <bvanassche@acm.org> writes:

> On 5/4/23 11:15, Andreas Hindborg wrote:
>> If it is still unclear to you why this effort was started, please do let
>> me know and I shall try to clarify further :)
>
> It seems like I was too polite in my previous email. What I meant is that
> rewriting code is useful if it provides a clear advantage to the users of
> a driver. For null_blk, the users are kernel developers. The code that has
> been posted is the start of a rewrite of the null_blk driver. The benefits
> of this rewrite (making low-level memory errors less likely) do not outweigh
> the risks that this effort will introduce functional or performance regressions.

If this turns in to a full rewrite instead of just a demonstrator, we
will be in the lucky situation that we have the existing C version to
verify performance and functionality against. Unnoticed regressions are
unlikely in this sense.

If we want to have Rust abstractions for the block layer in the kernel
(some people do), then having a simple driver in Rust to regression test
these abstractions with, is good value.

Best regards,
Andreas