From nobody Sat Oct 4 16:16:40 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DE5DC2D0C81; Fri, 15 Aug 2025 07:31:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755243107; cv=none; b=Kb89FRd7zhq34Qa/O45lsGboKsMlTDjvPPXl04E+VTEavZWlBjmeGGjZj5Z/h8JoHWeF+VOte4BetobJUEMZd52OxpMJAzagNXJ5fnPWEpwTndhAJCJ657u0Pcv5euFTI2U/doYKlPRE78u2oglWyZRLMGX+Nd7xzpIFImLeFw0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755243107; c=relaxed/simple; bh=iamvcpEdrA0t94Fax2Hfc94uf68XfdtGwPHLFZIDasU=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=oYVVWwDtAUrSD6z8tgehvMwT3cshO2f+5JN1oiP1GVYYwNuRdsbDUKY+9a963Z4M8yifwfTPo58MkA/O/TAVLEqbidSPmGWBf/4vwetXtLxvu+4fH39W7jW8jJgGPSZ7WL59QPYZ0hv14/Et/4t44/zY06il3wV++0liLQmwUHA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=e9yDbtqb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="e9yDbtqb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3069C4CEF4; Fri, 15 Aug 2025 07:31:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755243104; bh=iamvcpEdrA0t94Fax2Hfc94uf68XfdtGwPHLFZIDasU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=e9yDbtqbep4baLG42eBab5yyqvWNxTY3m51GB2djsUGN28ENjYTkWVXRTUJhBtXaj eSaRu7eZwsqfWXrLGTGTxfDocP/lJOknMHYEFVrvWyQ0Dt8UFQlgFImylBr2CTknaW oT/XccqEw0GmVZFPiHpMmOiKrx+LxVQ5F+JtVzD+7NSNcq6wSy7QSuRAaI+mB/pl6l HVtaIyFDZt6aNh52BTTJDI5/Z0mNFFiijXgtQtiXB9nbzBMNOQyU87YSL9wzWBNpZY GBJMl/XYjECA8uZKVgWJyOhOgDpMdlfOwgEbQMSpGZgGZuK+BCGYiY9hIzws8v5GT9 fAAuVUpJCzYyQ== From: Andreas Hindborg Date: Fri, 15 Aug 2025 09:30:50 +0200 Subject: [PATCH v5 15/18] rust: block: add `GenDisk` private data support Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250815-rnull-up-v6-16-v5-15-581453124c15@kernel.org> References: <20250815-rnull-up-v6-16-v5-0-581453124c15@kernel.org> In-Reply-To: <20250815-rnull-up-v6-16-v5-0-581453124c15@kernel.org> To: Boqun Feng , Miguel Ojeda , Alex Gaynor , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich , Jens Axboe , Breno Leitao Cc: linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Hindborg X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=10528; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=iamvcpEdrA0t94Fax2Hfc94uf68XfdtGwPHLFZIDasU=; b=owEBbQKS/ZANAwAIAeG4Gj55KGN3AcsmYgBonuJBmc3onlnFa71wVNzXzx82KMIaZZ449IcX8 WaPjXCquOiJAjMEAAEIAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaJ7iQQAKCRDhuBo+eShj dzrjD/9U1EapnRQqOPlm8EoUQZDlgbvgN9HOIIq8Ma9h7xEBKd0aWEIpuDctQ+alKoRn5Z0FUDj HVuXxpbBl4jW+NXRQdW4Fdlq4quk7RXXq9kDGuCWnyCBvN+GHzQ2NNPVYonH89fCI2G0moMQn66 CD9CT9mm5rtvaAopqSauCpZhSvngKBxykY8CtxwGuWa9vjru7Gy2U8Z5LDMA7vpk65cZMVO4P4p r6QfOazl+IKZd91FB9xFTGmZYbhroHdVW+6bAeHPqcNhDEE+3jjFzq38lBtZKG2aCm24cFFJvFY 42h4OniUPHJyGd2dt3TIqNDFzzkAIsJxV3SxdBSU3HwRQWBKthqU+8TFdOiTOdfweaLNfgypDQ/ pSnZL5f5czenNDDlJeQuQyAsgje7CebfMv1h30tYCQS05qeX8NpI+V9XTuVkkX++pE66fM4wWxC ELcI4KZimO/dsc1PMZ/otV5YyKbneTMHvxOTNJxOb7P4/ZMQw92Lr7gLMOC0OUwGiDdT6ZZabOv Gp68tYcx4zS5V3di1R+FaCp7zqWg+8nzzDjYO7hKW4bFP195QN1NXnFrZzI4IIaJ1zCaA1HEAgZ n+ArpKDq98HH0YzoIgl/TdVr/wKX9GyxRtnlJWJ5iKOM0JjO9hK+EewKfmSpDDnHSfbpg1fj9we 56sMCbgCrv1Pamg== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 Allow users of the rust block device driver API to install private data in the `GenDisk` structure. Signed-off-by: Andreas Hindborg Reviewed-by: Alice Ryhl --- drivers/block/rnull/rnull.rs | 8 ++++--- rust/kernel/block/mq.rs | 7 +++--- rust/kernel/block/mq/gen_disk.rs | 32 ++++++++++++++++++++++---- rust/kernel/block/mq/operations.rs | 46 ++++++++++++++++++++++++++++++----= ---- 4 files changed, 74 insertions(+), 19 deletions(-) diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs index d09bc77861e4..a012c59ecb3c 100644 --- a/drivers/block/rnull/rnull.rs +++ b/drivers/block/rnull/rnull.rs @@ -62,14 +62,16 @@ fn new( .logical_block_size(block_size)? .physical_block_size(block_size)? .rotational(rotational) - .build(fmt!("{}", name.to_str()?), tagset) + .build(fmt!("{}", name.to_str()?), tagset, ()) } } =20 #[vtable] impl Operations for NullBlkDevice { + type QueueData =3D (); + #[inline(always)] - fn queue_rq(rq: ARef>, _is_last: bool) -> Result { + fn queue_rq(_queue_data: (), rq: ARef>, _is_last: bo= ol) -> Result { mq::Request::end_ok(rq) .map_err(|_e| kernel::error::code::EIO) // We take no refcounts on the request, so we expect to be abl= e to @@ -80,5 +82,5 @@ fn queue_rq(rq: ARef>, _is_last: bool) = -> Result { Ok(()) } =20 - fn commit_rqs() {} + fn commit_rqs(_queue_data: ()) {} } diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs index 98fa0d6bc8f7..6e546f4f3d1c 100644 --- a/rust/kernel/block/mq.rs +++ b/rust/kernel/block/mq.rs @@ -69,20 +69,21 @@ //! //! #[vtable] //! impl Operations for MyBlkDevice { +//! type QueueData =3D (); //! -//! fn queue_rq(rq: ARef>, _is_last: bool) -> Result { +//! fn queue_rq(_queue_data: (), rq: ARef>, _is_last: bo= ol) -> Result { //! Request::end_ok(rq); //! Ok(()) //! } //! -//! fn commit_rqs() {} +//! fn commit_rqs(_queue_data: ()) {} //! } //! //! let tagset: Arc> =3D //! Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; //! let mut disk =3D gen_disk::GenDiskBuilder::new() //! .capacity_sectors(4096) -//! .build(format_args!("myblk"), tagset)?; +//! .build(format_args!("myblk"), tagset, ())?; //! //! # Ok::<(), kernel::error::Error>(()) //! ``` diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_di= sk.rs index 6b1b846874db..ac7a33a00aaa 100644 --- a/rust/kernel/block/mq/gen_disk.rs +++ b/rust/kernel/block/mq/gen_disk.rs @@ -13,6 +13,7 @@ static_lock_class, str::NullTerminatedFormatter, sync::Arc, + types::{ForeignOwnable, ScopeGuard}, }; use core::fmt::{self, Write}; =20 @@ -98,7 +99,14 @@ pub fn build( self, name: fmt::Arguments<'_>, tagset: Arc>, + queue_data: T::QueueData, ) -> Result> { + let data =3D queue_data.into_foreign(); + let recover_data =3D ScopeGuard::new(|| { + // SAFETY: T::QueueData was created by the call to `into_forei= gn()` above + drop(unsafe { T::QueueData::from_foreign(data) }); + }); + // SAFETY: `bindings::queue_limits` contain only fields that are v= alid when zeroed. let mut lim: bindings::queue_limits =3D unsafe { core::mem::zeroed= () }; =20 @@ -113,7 +121,7 @@ pub fn build( bindings::__blk_mq_alloc_disk( tagset.raw_tag_set(), &mut lim, - core::ptr::null_mut(), + data.cast(), static_lock_class!().as_ptr(), ) })?; @@ -167,8 +175,12 @@ pub fn build( }, )?; =20 + recover_data.dismiss(); + // INVARIANT: `gendisk` was initialized above. // INVARIANT: `gendisk` was added to the VFS via `device_add_disk`= above. + // INVARIANT: `gendisk.queue.queue_data` is set to `data` in the c= all to + // `__blk_mq_alloc_disk` above. Ok(GenDisk { _tagset: tagset, gendisk, @@ -180,9 +192,10 @@ pub fn build( /// /// # Invariants /// -/// - `gendisk` must always point to an initialized and valid `struct gend= isk`. -/// - `gendisk` was added to the VFS through a call to -/// `bindings::device_add_disk`. +/// - `gendisk` must always point to an initialized and valid `struct gen= disk`. +/// - `gendisk` was added to the VFS through a call to +/// `bindings::device_add_disk`. +/// - `self.gendisk.queue.queuedata` is initialized by a call to `Foreign= Ownable::into_foreign`. pub struct GenDisk { _tagset: Arc>, gendisk: *mut bindings::gendisk, @@ -194,9 +207,20 @@ unsafe impl Send for GenDisk = {} =20 impl Drop for GenDisk { fn drop(&mut self) { + // SAFETY: By type invariant of `Self`, `self.gendisk` points to a= valid + // and initialized instance of `struct gendisk`, and, `queuedata` = was + // initialized with the result of a call to + // `ForeignOwnable::into_foreign`. + let queue_data =3D unsafe { (*(*self.gendisk).queue).queuedata }; + // SAFETY: By type invariant, `self.gendisk` points to a valid and // initialized instance of `struct gendisk`, and it was previously= added // to the VFS. unsafe { bindings::del_gendisk(self.gendisk) }; + + // SAFETY: `queue.queuedata` was created by `GenDiskBuilder::build= ` with + // a call to `ForeignOwnable::into_foreign` to create `queuedata`. + // `ForeignOwnable::from_foreign` is only called here. + drop(unsafe { T::QueueData::from_foreign(queue_data) }); } } diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/oper= ations.rs index c2b98f507bcb..6fb256f55acc 100644 --- a/rust/kernel/block/mq/operations.rs +++ b/rust/kernel/block/mq/operations.rs @@ -6,14 +6,15 @@ =20 use crate::{ bindings, - block::mq::request::RequestDataWrapper, - block::mq::Request, + block::mq::{request::RequestDataWrapper, Request}, error::{from_result, Result}, prelude::*, - types::ARef, + types::{ARef, ForeignOwnable}, }; use core::{marker::PhantomData, sync::atomic::AtomicU64, sync::atomic::Ord= ering}; =20 +type ForeignBorrowed<'a, T> =3D ::Borrowed<'a>; + /// Implement this trait to interface blk-mq as block devices. /// /// To implement a block device driver, implement this trait as described = in the @@ -26,12 +27,20 @@ /// [module level documentation]: kernel::block::mq #[macros::vtable] pub trait Operations: Sized { + /// Data associated with the `struct request_queue` that is allocated = for + /// the `GenDisk` associated with this `Operations` implementation. + type QueueData: ForeignOwnable; + /// Called by the kernel to queue a request with the driver. If `is_la= st` is /// `false`, the driver is allowed to defer committing the request. - fn queue_rq(rq: ARef>, is_last: bool) -> Result; + fn queue_rq( + queue_data: ForeignBorrowed<'_, Self::QueueData>, + rq: ARef>, + is_last: bool, + ) -> Result; =20 /// Called by the kernel to indicate that queued requests should be su= bmitted. - fn commit_rqs(); + fn commit_rqs(queue_data: ForeignBorrowed<'_, Self::QueueData>); =20 /// Called by the kernel to poll the device for completed requests. On= ly /// used for poll queues. @@ -70,7 +79,7 @@ impl OperationsVTable { /// promise to not access the request until the driver calls /// `bindings::blk_mq_end_request` for the request. unsafe extern "C" fn queue_rq_callback( - _hctx: *mut bindings::blk_mq_hw_ctx, + hctx: *mut bindings::blk_mq_hw_ctx, bd: *const bindings::blk_mq_queue_data, ) -> bindings::blk_status_t { // SAFETY: `bd.rq` is valid as required by the safety requirement = for @@ -88,10 +97,20 @@ impl OperationsVTable { // reference counted by `ARef` until then. let rq =3D unsafe { Request::aref_from_raw((*bd).rq) }; =20 + // SAFETY: `hctx` is valid as required by this function. + let queue_data =3D unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDisk::try_new()` w= ith a + // call to `ForeignOwnable::into_pointer()` to create `queuedata`. + // `ForeignOwnable::from_foreign()` is only called when the tagset= is + // dropped, which happens after we are dropped. + let queue_data =3D unsafe { T::QueueData::borrow(queue_data) }; + // SAFETY: We have exclusive access and we just set the refcount a= bove. unsafe { Request::start_unchecked(&rq) }; =20 let ret =3D T::queue_rq( + queue_data, rq, // SAFETY: `bd` is valid as required by the safety requirement= for // this function. @@ -110,9 +129,18 @@ impl OperationsVTable { /// /// # Safety /// - /// This function may only be called by blk-mq C infrastructure. - unsafe extern "C" fn commit_rqs_callback(_hctx: *mut bindings::blk_mq_= hw_ctx) { - T::commit_rqs() + /// This function may only be called by blk-mq C infrastructure. The c= aller + /// must ensure that `hctx` is valid. + unsafe extern "C" fn commit_rqs_callback(hctx: *mut bindings::blk_mq_h= w_ctx) { + // SAFETY: `hctx` is valid as required by this function. + let queue_data =3D unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDisk::try_new()` w= ith a + // call to `ForeignOwnable::into_pointer()` to create `queuedata`. + // `ForeignOwnable::from_foreign()` is only called when the tagset= is + // dropped, which happens after we are dropped. + let queue_data =3D unsafe { T::QueueData::borrow(queue_data) }; + T::commit_rqs(queue_data) } =20 /// This function is called by the C kernel. It is not currently --=20 2.47.2