rust: block: add `GenDisk` private data support (90d952fa) · Commits · git / linux-net

drivers/block/rnull/rnull.rs

+5 −3

Original line number	Diff line number	Diff line
		@@ -61,14 +61,16 @@ 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<mq::Request<Self>>, _is_last: bool) -> Result {
		fn queue_rq(_queue_data: (), rq: ARef<mq::Request<Self>>, _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
		@@ -79,5 +81,5 @@ fn queue_rq(rq: ARef<mq::Request<Self>>, _is_last: bool) -> Result {
		Ok(())
		}

		fn commit_rqs() {}
		fn commit_rqs(_queue_data: ()) {}
		}

rust/kernel/block/mq.rs

+4 −3

Original line number	Diff line number	Diff line
		@@ -69,20 +69,21 @@
		//!
		//! #[vtable]
		//! impl Operations for MyBlkDevice {
		//! type QueueData = ();
		//!
		//! fn queue_rq(rq: ARef<Request<Self>>, _is_last: bool) -> Result {
		//! fn queue_rq(_queue_data: (), rq: ARef<Request<Self>>, _is_last: bool) -> Result {
		//! Request::end_ok(rq);
		//! Ok(())
		//! }
		//!
		//! fn commit_rqs() {}
		//! fn commit_rqs(_queue_data: ()) {}
		//! }
		//!
		//! let tagset: Arc<TagSet<MyBlkDevice>> =
		//! 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>(())
		//! ```

rust/kernel/block/mq/gen_disk.rs

+28 −4

Original line number	Diff line number	Diff line
		@@ -13,6 +13,7 @@
		static_lock_class,
		str::NullTerminatedFormatter,
		sync::Arc,
		types::{ForeignOwnable, ScopeGuard},
		};
		use core::fmt::{self, Write};

		@@ -98,7 +99,14 @@ pub fn build<T: Operations>(
		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,
		static_lock_class!().as_ptr(),
		)
		})?;
		@@ -167,8 +175,12 @@ pub fn build<T: Operations>(
		},
		)?;

		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,
		@@ -183,6 +195,7 @@ pub fn build<T: Operations>(
		/// - `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<T: Operations> {
		_tagset: Arc<TagSet<T>>,
		gendisk: *mut bindings::gendisk,
		@@ -194,9 +207,20 @@ unsafe impl<T: Operations + Send> Send for GenDisk<T> {}

		impl<T: Operations> Drop for GenDisk<T> {
		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.
		drop(unsafe { T::QueueData::from_foreign(queue_data) });
		}
		}

rust/kernel/block/mq/operations.rs

+37 −9

Original line number	Diff line number	Diff line
		@@ -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> = <T as ForeignOwnable>::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<Request<Self>>, is_last: bool) -> Result;
		fn queue_rq(
		queue_data: ForeignBorrowed<'_, Self::QueueData>,
		rq: ARef<Request<Self>>,
		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<T: Operations> OperationsVTable<T> {
		/// 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<T: Operations> OperationsVTable<T> {
		// 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 `GenDiskBuilder::build` with
		// a call to `ForeignOwnable::into_foreign` 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) };

		// 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<T: Operations> OperationsVTable<T> {
		///
		/// # 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_foreign()` 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) };
		T::commit_rqs(queue_data)
		}

		/// This function is called by the C kernel. It is not currently