From mboxrd@z Thu Jan 1 00:00:00 1970 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 3F9022EA463; Fri, 11 Jul 2025 11:44:21 +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=1752234261; cv=none; b=X3MADSiFNM3+yppTpV0Bkihf8N4ek6tXsxdJMo+C2liPnfCCrss8wE6tgZktiZJy/PDKuNKbwEB0Pq3xYjMoLmLPWLWa7GIaVHVtj8hU8wiGQFXECy/meNNTZP6205jzixWJBoOInK9CXXKnsNnp8sJeVuBghXVLNzPwmC5184g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752234261; c=relaxed/simple; bh=8EIFORhiI91k51v/6Z1Q3xAZrwAWnbDgqdU03+cKtQI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=iVM5WpG2oFz48C8jZgCVzgYCbb/ymjSAz57w1RbH7IHn7C2+8jUfKTA/DN9kIrWLGt8F6dLVOwrhbJVbNj4YzSDtDOq7Y42gxQzMowY7CqexJ18hczxRVv1rlD+WF1DhRJhiuGIA9M0mniJVg//R+Hi4fYneeiiejgttuvPZgFs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GRTR66LG; 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="GRTR66LG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66C3BC4CEF4; Fri, 11 Jul 2025 11:44:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752234261; bh=8EIFORhiI91k51v/6Z1Q3xAZrwAWnbDgqdU03+cKtQI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=GRTR66LGeIw1pQOogW+oWfnhyELRcFY+yjk7HUDxGdg/MKeDxTZvdgYD7IubnwCgI VWzL164fr3lI2W5+q4n3F+lo7MRFCpuV/XGkEgf9LnsTSlw4JPfySv+J9Wi6ILIIVY pfwGef1SbSM2oq7N4qKyjE+koawP6zbkOimRXzRz2NX9rU5DCFWe5BKDY2VDydsWNi OkjBH7XHDpKFyILZRoTmwLFKRL03edsX7236U0JXJZ8L1E1jFWwhBriLlnQ2tPTAoI g3R3n5rPIDGEhXGdTlhsCVm+nQMkbxrtvH2/ykAPhGTkUr36PMnbCCSzzt39lTF6uE HvDKBrZbyHrQg== From: Andreas Hindborg Date: Fri, 11 Jul 2025 13:43:14 +0200 Subject: [PATCH v3 13/16] rust: block: add `GenDisk` private data support Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250711-rnull-up-v6-16-v3-13-3a262b4e2921@kernel.org> References: <20250711-rnull-up-v6-16-v3-0-3a262b4e2921@kernel.org> In-Reply-To: <20250711-rnull-up-v6-16-v3-0-3a262b4e2921@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 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=10555; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=8EIFORhiI91k51v/6Z1Q3xAZrwAWnbDgqdU03+cKtQI=; b=owEBbQKS/ZANAwAIAeG4Gj55KGN3AcsmYgBocPjVt9ul3aKi8XBriFTHyx6qC0mFonSLdusJW IMtNoUaikKJAjMEAAEIAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaHD41QAKCRDhuBo+eShj d5tBD/0UoubIR3NJ4xd2RrvxL2tZIKTKSQpq/X6fbRiYTOLR6zLJrM51HQXBbnxVTkwOBy1rS4m HJ89jeYaq/2r5PYPerMPwPumPQnVqfVrt4TkgZNq+AJhOK44C9eui9h45b4PNR0bJKn9hfAtSDM rf5kECy9w9yS+T1kDjSw0tPSq1BdfKegvaJmxsAv2ckODxy2EKibCg/qMiLO1MjpNkfHym1ueq6 j9N0lDbnm7nyAzNeonphKLyolbUTBwpR3/5UgywOOKWD2KuYoASsjZwpeFjAUErnx2mR+f2ryMh itkcHoQUFSCujnMu2jIPYfFq8IhHN47Lvn0oLUjUc8oscrx0FAdGFr0CNlxSGAWiWHZPaCjkoy0 a7FnZyXKQoK0SnXCPARdShKpY0YTOsFn+oU19eRpxsplfxFUiBTzzITSqQw2F62+kmkI6DzLIs/ ivQVtQ8YDRyV1lBHKE2URaQ9wjSrFODyjEUQCUTpfMkJMdQcBRKQa68IMkTAMaGDJ1CQDXVOe83 GrfH4EVqdy4wLUt67E0tdisBM55s77SLxmhpAljpvmfSxcWIpTNAkGgLlv0Dzg/aJKQJG+KF4Uh qShRCdQlHDbXDd1QK1YB37PO8nrPB1vOb7XT/0HbfFaEFSIRAqu/FHW4vGQS6LBEojdF7T/HIjw NPPzNcCGr3QRKlg== 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 --- 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, ()) } } #[vtable] impl Operations for NullBlkDevice { + type QueueData = (); + #[inline(always)] - fn queue_rq(rq: ARef>, _is_last: bool) -> Result { + fn queue_rq(_queue_data: (), rq: ARef>, _is_last: bool) -> 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 able to @@ -80,5 +82,5 @@ fn queue_rq(rq: ARef>, _is_last: bool) -> Result { Ok(()) } - fn commit_rqs() {} + fn commit_rqs(_queue_data: ()) {} } diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs index faa3ccb5a49a..34b7425fa94d 100644 --- a/rust/kernel/block/mq.rs +++ b/rust/kernel/block/mq.rs @@ -69,20 +69,21 @@ //! //! #[vtable] //! impl Operations for MyBlkDevice { +//! type QueueData = (); //! -//! fn queue_rq(rq: ARef>, _is_last: bool) -> Result { +//! fn queue_rq(_queue_data: (), rq: ARef>, _is_last: bool) -> Result { //! Request::end_ok(rq); //! Ok(()) //! } //! -//! fn commit_rqs() {} +//! fn commit_rqs(_queue_data: ()) {} //! } //! //! let tagset: Arc> = //! Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; //! let mut disk = 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_disk.rs index 7ab049ec591b..954bc64cfa59 100644 --- a/rust/kernel/block/mq/gen_disk.rs +++ b/rust/kernel/block/mq/gen_disk.rs @@ -12,6 +12,7 @@ static_lock_class, str::NullTerminatedFormatter, sync::Arc, + types::{ForeignOwnable, ScopeGuard}, }; use core::fmt::{self, Write}; @@ -97,7 +98,14 @@ pub fn build( self, name: fmt::Arguments<'_>, tagset: Arc>, + queue_data: T::QueueData, ) -> Result> { + let data = queue_data.into_foreign(); + let recover_data = ScopeGuard::new(|| { + // SAFETY: T::QueueData was created by the call to `into_foreign()` above + 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() }; @@ -112,7 +120,7 @@ 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(), ) })?; @@ -166,8 +174,12 @@ pub fn build( }, )?; + 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 call to + // `__blk_mq_alloc_disk` above. Ok(GenDisk { _tagset: tagset, gendisk, @@ -179,9 +191,10 @@ pub fn build( /// /// # Invariants /// -/// - `gendisk` must always point to an initialized and valid `struct gendisk`. -/// - `gendisk` was added to the VFS through a call to -/// `bindings::device_add_disk`. +/// - `gendisk` must always point to an initialized and valid `struct gendisk`. +/// - `gendisk` was added to the VFS through a call to +/// `bindings::device_add_disk`. +/// - `self.gendisk.queue.queuedata` is initialized by a call to `ForeignOwnable::into_foreign`. pub struct GenDisk { _tagset: Arc>, gendisk: *mut bindings::gendisk, @@ -193,9 +206,20 @@ unsafe impl Send for GenDisk {} 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 = 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. + let _queue_data = unsafe { T::QueueData::from_foreign(queue_data.cast()) }; } } diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/operations.rs index 864ff379dc91..c50959d5517b 100644 --- a/rust/kernel/block/mq/operations.rs +++ b/rust/kernel/block/mq/operations.rs @@ -6,14 +6,15 @@ 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::Ordering}; +type ForeignBorrowed<'a, T> = ::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_last` 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; /// Called by the kernel to indicate that queued requests should be submitted. - fn commit_rqs(); + fn commit_rqs(queue_data: ForeignBorrowed<'_, Self::QueueData>); /// Called by the kernel to poll the device for completed requests. Only /// 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 = unsafe { Request::aref_from_raw((*bd).rq) }; + // SAFETY: `hctx` is valid as required by this function. + let queue_data = unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDisk::try_new()` with 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 = unsafe { T::QueueData::borrow(queue_data.cast()) }; + // SAFETY: We have exclusive access and we just set the refcount above. unsafe { Request::start_unchecked(&rq) }; let ret = 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 caller + /// must ensure that `hctx` is valid. + unsafe extern "C" fn commit_rqs_callback(hctx: *mut bindings::blk_mq_hw_ctx) { + // SAFETY: `hctx` is valid as required by this function. + let queue_data = unsafe { (*(*hctx).queue).queuedata }; + + // SAFETY: `queue.queuedata` was created by `GenDisk::try_new()` with 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 = unsafe { T::QueueData::borrow(queue_data.cast()) }; + T::commit_rqs(queue_data) } /// This function is called by the C kernel. It is not currently -- 2.47.2