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From: Andreas Hindborg <a.hindborg@kernel.org>
To: Alice Ryhl <aliceryhl@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>, Miguel Ojeda <ojeda@kernel.org>, Alex
 Gaynor <alex.gaynor@gmail.com>, Gary Guo <gary@garyguo.net>, =?utf-8?Q?Bj?=
 =?utf-8?Q?=C3=B6rn?= Roy
 Baron <bjorn3_gh@protonmail.com>, Benno Lossin <lossin@kernel.org>, Trevor
 Gross <tmgross@umich.edu>, Danilo Krummrich <dakr@kernel.org>, Jens Axboe
 <axboe@kernel.dk>, Breno Leitao <leitao@debian.org>,
 linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 15/18] rust: block: add `GenDisk` private data support
In-Reply-To: <aJ7tcmOHfFmHgrY9@google.com>
References: <20250815-rnull-up-v6-16-v5-0-581453124c15@kernel.org>
 <20250815-rnull-up-v6-16-v5-15-581453124c15@kernel.org>
 <Addn5RH8T6dPmcfVeF6HXK4Q3rVuAz-0N8es2JtgnRl3UhXIJhicxoB5Ns_F8aD2-sflnPXC6oeBQDLtCfXtLA==@protonmail.internalid>
 <aJ7tcmOHfFmHgrY9@google.com>
Date: Fri, 15 Aug 2025 11:08:59 +0200
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"Alice Ryhl" <aliceryhl@google.com> writes:

> On Fri, Aug 15, 2025 at 09:30:50AM +0200, Andreas Hindborg wrote:
>> Allow users of the rust block device driver API to install private data in
>> the `GenDisk` structure.
>>
>> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
>
> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
>
>>          self,
>>          name: fmt::Arguments<'_>,
>>          tagset: Arc<TagSet<T>>,
>> +        queue_data: T::QueueData,
>>      ) -> Result<GenDisk<T>> {
>> +        let data = queue_data.into_foreign();
>> +        let recover_data = ScopeGuard::new(|| {
>> +            // SAFETY: T::QueueData was created by the call to `into_foreign()` above
>> +            drop(unsafe { T::QueueData::from_foreign(data) });
>> +        });
>> +
>>          // SAFETY: `bindings::queue_limits` contain only fields that are valid when zeroed.
>>          let mut lim: bindings::queue_limits = unsafe { core::mem::zeroed() };
>>
>> @@ -113,7 +121,7 @@ pub fn build<T: Operations>(
>>              bindings::__blk_mq_alloc_disk(
>>                  tagset.raw_tag_set(),
>>                  &mut lim,
>> -                core::ptr::null_mut(),
>> +                data.cast(),
>
> Is the cast necessary?

Not any longer, no.


Best regards,
Andreas Hindborg