From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx> Add initial abstractions for working with blk-mq. This patch is a maintained, refactored subset of code originally published by Wedson Almeida Filho <wedsonaf@xxxxxxxxx> [1]. [1] https://github.com/wedsonaf/linux/tree/f2cfd2fe0e2ca4e90994f96afe268bbd4382a891/rust/kernel/blk/mq.rs Cc: Wedson Almeida Filho <wedsonaf@xxxxxxxxx> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx> --- rust/bindings/bindings_helper.h | 2 + rust/helpers.c | 22 +++ rust/kernel/block.rs | 5 + rust/kernel/block/mq.rs | 15 ++ rust/kernel/block/mq/gen_disk.rs | 133 +++++++++++++++ rust/kernel/block/mq/operations.rs | 260 +++++++++++++++++++++++++++++ rust/kernel/block/mq/raw_writer.rs | 30 ++++ rust/kernel/block/mq/request.rs | 71 ++++++++ rust/kernel/block/mq/tag_set.rs | 92 ++++++++++ rust/kernel/error.rs | 4 + rust/kernel/lib.rs | 1 + 11 files changed, 635 insertions(+) create mode 100644 rust/kernel/block.rs create mode 100644 rust/kernel/block/mq.rs create mode 100644 rust/kernel/block/mq/gen_disk.rs create mode 100644 rust/kernel/block/mq/operations.rs create mode 100644 rust/kernel/block/mq/raw_writer.rs create mode 100644 rust/kernel/block/mq/request.rs create mode 100644 rust/kernel/block/mq/tag_set.rs diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index 52834962b94d..86c07eeb1ba1 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -11,6 +11,8 @@ #include <linux/wait.h> #include <linux/sched.h> #include <linux/radix-tree.h> +#include <linux/blk_types.h> +#include <linux/blk-mq.h> /* `bindgen` gets confused at certain things. */ const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL; diff --git a/rust/helpers.c b/rust/helpers.c index 9bd9d95da951..a59341084774 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -18,6 +18,7 @@ * accidentally exposed. */ +#include <linux/bio.h> #include <linux/bug.h> #include <linux/build_bug.h> #include <linux/err.h> @@ -28,6 +29,8 @@ #include <linux/wait.h> #include <linux/radix-tree.h> #include <linux/highmem.h> +#include <linux/blk-mq.h> +#include <linux/blkdev.h> __noreturn void rust_helper_BUG(void) { @@ -130,6 +133,25 @@ void rust_helper_put_task_struct(struct task_struct *t) } EXPORT_SYMBOL_GPL(rust_helper_put_task_struct); +struct bio_vec rust_helper_req_bvec(struct request *rq) +{ + return req_bvec(rq); +} +EXPORT_SYMBOL_GPL(rust_helper_req_bvec); + +void *rust_helper_blk_mq_rq_to_pdu(struct request *rq) +{ + return blk_mq_rq_to_pdu(rq); +} +EXPORT_SYMBOL_GPL(rust_helper_blk_mq_rq_to_pdu); + +void rust_helper_bio_advance_iter_single(const struct bio *bio, + struct bvec_iter *iter, + unsigned int bytes) { + bio_advance_iter_single(bio, iter, bytes); +} +EXPORT_SYMBOL_GPL(rust_helper_bio_advance_iter_single); + void rust_helper_init_radix_tree(struct xarray *tree, gfp_t gfp_mask) { INIT_RADIX_TREE(tree, gfp_mask); diff --git a/rust/kernel/block.rs b/rust/kernel/block.rs new file mode 100644 index 000000000000..4c93317a568a --- /dev/null +++ b/rust/kernel/block.rs @@ -0,0 +1,5 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Types for working with the block layer + +pub mod mq; diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs new file mode 100644 index 000000000000..5b40f6a73c0f --- /dev/null +++ b/rust/kernel/block/mq.rs @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! This module provides types for implementing drivers that interface the +//! blk-mq subsystem + +mod gen_disk; +mod operations; +mod raw_writer; +mod request; +mod tag_set; + +pub use gen_disk::GenDisk; +pub use operations::Operations; +pub use request::Request; +pub use tag_set::TagSet; diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs new file mode 100644 index 000000000000..50496af15bbf --- /dev/null +++ b/rust/kernel/block/mq/gen_disk.rs @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! GenDisk abstraction +//! +//! C header: [`include/linux/blkdev.h`](../../include/linux/blkdev.h) +//! C header: [`include/linux/blk_mq.h`](../../include/linux/blk_mq.h) + +use crate::block::mq::{raw_writer::RawWriter, Operations, TagSet}; +use crate::{ + bindings, error::from_err_ptr, error::Result, sync::Arc, types::ForeignOwnable, + types::ScopeGuard, +}; +use core::fmt::{self, Write}; + +/// A generic block device +/// +/// # Invariants +/// +/// - `gendisk` must always point to an initialized and valid `struct gendisk`. +pub struct GenDisk<T: Operations> { + _tagset: Arc<TagSet<T>>, + gendisk: *mut bindings::gendisk, +} + +// SAFETY: `GenDisk` is an owned pointer to a `struct gendisk` and an `Arc` to a +// `TagSet` It is safe to send this to other threads as long as T is Send. +unsafe impl<T: Operations + Send> Send for GenDisk<T> {} + +impl<T: Operations> GenDisk<T> { + /// Try to create a new `GenDisk` + pub fn try_new(tagset: Arc<TagSet<T>>, queue_data: T::QueueData) -> Result<Self> { + 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) }; + }); + + let lock_class_key = crate::sync::LockClassKey::new(); + + // SAFETY: `tagset.raw_tag_set()` points to a valid and initialized tag set + let gendisk = from_err_ptr(unsafe { + bindings::__blk_mq_alloc_disk(tagset.raw_tag_set(), data as _, lock_class_key.as_ptr()) + })?; + + const TABLE: bindings::block_device_operations = bindings::block_device_operations { + submit_bio: None, + open: None, + release: None, + ioctl: None, + compat_ioctl: None, + check_events: None, + unlock_native_capacity: None, + getgeo: None, + set_read_only: None, + swap_slot_free_notify: None, + report_zones: None, + devnode: None, + alternative_gpt_sector: None, + get_unique_id: None, + owner: core::ptr::null_mut(), + pr_ops: core::ptr::null_mut(), + free_disk: None, + poll_bio: None, + }; + + // SAFETY: gendisk is a valid pointer as we initialized it above + unsafe { (*gendisk).fops = &TABLE }; + + recover_data.dismiss(); + Ok(Self { + _tagset: tagset, + gendisk, + }) + } + + /// Set the name of the device + pub fn set_name(&self, args: fmt::Arguments<'_>) -> Result { + let mut raw_writer = RawWriter::from_array(unsafe { &mut (*self.gendisk).disk_name }); + raw_writer.write_fmt(args)?; + raw_writer.write_char('\0')?; + Ok(()) + } + + /// Register the device with the kernel. When this function return, the + /// device is accessible from VFS. The kernel may issue reads to the device + /// during registration to discover partition infomation. + pub fn add(&self) -> Result { + crate::error::to_result(unsafe { + bindings::device_add_disk(core::ptr::null_mut(), self.gendisk, core::ptr::null_mut()) + }) + } + + /// Call to tell the block layer the capcacity of the device + pub fn set_capacity(&self, sectors: u64) { + unsafe { bindings::set_capacity(self.gendisk, sectors) }; + } + + /// Set the logical block size of the device + pub fn set_queue_logical_block_size(&self, size: u32) { + unsafe { bindings::blk_queue_logical_block_size((*self.gendisk).queue, size) }; + } + + /// Set the physical block size of the device + pub fn set_queue_physical_block_size(&self, size: u32) { + unsafe { bindings::blk_queue_physical_block_size((*self.gendisk).queue, size) }; + } + + /// Set the rotational media attribute for the device + pub fn set_rotational(&self, rotational: bool) { + if !rotational { + unsafe { + bindings::blk_queue_flag_set(bindings::QUEUE_FLAG_NONROT, (*self.gendisk).queue) + }; + } else { + unsafe { + bindings::blk_queue_flag_clear(bindings::QUEUE_FLAG_NONROT, (*self.gendisk).queue) + }; + } + } +} + +impl<T: Operations> Drop for GenDisk<T> { + fn drop(&mut self) { + let queue_data = unsafe { (*(*self.gendisk).queue).queuedata }; + + unsafe { bindings::del_gendisk(self.gendisk) }; + + // 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 here. + let _queue_data = unsafe { T::QueueData::from_foreign(queue_data) }; + } +} diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/operations.rs new file mode 100644 index 000000000000..fb1ab707d1f0 --- /dev/null +++ b/rust/kernel/block/mq/operations.rs @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! This module provides an interface for blk-mq drivers to implement. +//! +//! C header: [`include/linux/blk-mq.h`](../../include/linux/blk-mq.h) + +use crate::{ + bindings, + block::mq::{tag_set::TagSetRef, Request}, + error::{from_result, Result}, + types::ForeignOwnable, +}; +use core::{marker::PhantomData, pin::Pin}; + +/// Implement this trait to interface blk-mq as block devices +#[macros::vtable] +pub trait Operations: Sized { + /// Data associated with a request. This data is located next to the request + /// structure. + type RequestData; + + /// Data associated with the `struct request_queue` that is allocated for + /// the `GenDisk` associated with this `Operations` implementation. + type QueueData: ForeignOwnable; + + /// Data associated with a dispatch queue. This is stored as a pointer in + /// `struct blk_mq_hw_ctx`. + type HwData: ForeignOwnable; + + /// Data associated with a tag set. This is stored as a pointer in `struct + /// blk_mq_tag_set`. + type TagSetData: ForeignOwnable; + + /// Called by the kernel to allocate a new `RequestData`. The structure will + /// eventually be pinned, so defer initialization to `init_request_data()` + fn new_request_data( + _tagset_data: <Self::TagSetData as ForeignOwnable>::Borrowed<'_>, + ) -> Result<Self::RequestData>; + + /// Called by the kernel to initialize a previously allocated `RequestData` + fn init_request_data( + _tagset_data: <Self::TagSetData as ForeignOwnable>::Borrowed<'_>, + _data: Pin<&mut Self::RequestData>, + ) -> Result { + Ok(()) + } + + /// Called by the kernel to queue a request with the driver. If `is_last` is + /// `false`, the driver is allowed to defer commiting the request. + fn queue_rq( + hw_data: <Self::HwData as ForeignOwnable>::Borrowed<'_>, + queue_data: <Self::QueueData as ForeignOwnable>::Borrowed<'_>, + rq: &Request<Self>, + is_last: bool, + ) -> Result; + + /// Called by the kernel to indicate that queued requests should be submitted + fn commit_rqs( + hw_data: <Self::HwData as ForeignOwnable>::Borrowed<'_>, + queue_data: <Self::QueueData as ForeignOwnable>::Borrowed<'_>, + ); + + /// Called by the kernel when the request is completed + fn complete(_rq: &Request<Self>); + + /// Called by the kernel to allocate and initialize a driver specific hardware context data + fn init_hctx( + tagset_data: <Self::TagSetData as ForeignOwnable>::Borrowed<'_>, + hctx_idx: u32, + ) -> Result<Self::HwData>; + + /// Called by the kernel to poll the device for completed requests. Only used for poll queues. + fn poll(_hw_data: <Self::HwData as ForeignOwnable>::Borrowed<'_>) -> i32 { + unreachable!() + } + + /// Called by the kernel to map submission queues to CPU cores. + fn map_queues(_tag_set: &TagSetRef) { + unreachable!() + } + + // There is no need for exit_request() because `drop` will be called. +} + +pub(crate) struct OperationsVtable<T: Operations>(PhantomData<T>); + +impl<T: Operations> OperationsVtable<T> { + // # Safety + // + // The caller of this function must ensure that `hctx` and `bd` are valid + // and initialized. The pointees must outlive this function. Further + // `hctx->driver_data` must be a pointer created by a call to + // `Self::init_hctx_callback()` and the pointee must outlive this function. + // This function must not be called with a `hctx` for which + // `Self::exit_hctx_callback()` has been called. + unsafe extern "C" fn queue_rq_callback( + hctx: *mut bindings::blk_mq_hw_ctx, + bd: *const bindings::blk_mq_queue_data, + ) -> bindings::blk_status_t { + // SAFETY: `bd` is valid as required by the safety requirement for this function. + let rq = unsafe { (*bd).rq }; + + // SAFETY: The safety requirement for this function ensure that + // `(*hctx).driver_data` was returned by a call to + // `Self::init_hctx_callback()`. That function uses + // `PointerWrapper::into_pointer()` to create `driver_data`. Further, + // the returned value does not outlive this function and + // `from_foreign()` is not called until `Self::exit_hctx_callback()` is + // called. By the safety requirement of this function and contract with + // the `blk-mq` API, `queue_rq_callback()` will not be called after that + // point. + let hw_data = unsafe { T::HwData::borrow((*hctx).driver_data) }; + + // 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) }; + + // SAFETY: `bd` is valid as required by the safety requirement for this function. + let ret = T::queue_rq( + hw_data, + queue_data, + &unsafe { Request::from_ptr(rq) }, + unsafe { (*bd).last }, + ); + if let Err(e) = ret { + e.to_blk_status() + } else { + bindings::BLK_STS_OK as _ + } + } + + unsafe extern "C" fn commit_rqs_callback(hctx: *mut bindings::blk_mq_hw_ctx) { + let hw_data = unsafe { T::HwData::borrow((*hctx).driver_data) }; + + // 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) }; + T::commit_rqs(hw_data, queue_data) + } + + unsafe extern "C" fn complete_callback(rq: *mut bindings::request) { + T::complete(&unsafe { Request::from_ptr(rq) }); + } + + unsafe extern "C" fn poll_callback( + hctx: *mut bindings::blk_mq_hw_ctx, + _iob: *mut bindings::io_comp_batch, + ) -> core::ffi::c_int { + let hw_data = unsafe { T::HwData::borrow((*hctx).driver_data) }; + T::poll(hw_data) + } + + unsafe extern "C" fn init_hctx_callback( + hctx: *mut bindings::blk_mq_hw_ctx, + tagset_data: *mut core::ffi::c_void, + hctx_idx: core::ffi::c_uint, + ) -> core::ffi::c_int { + from_result(|| { + let tagset_data = unsafe { T::TagSetData::borrow(tagset_data) }; + let data = T::init_hctx(tagset_data, hctx_idx)?; + unsafe { (*hctx).driver_data = data.into_foreign() as _ }; + Ok(0) + }) + } + + unsafe extern "C" fn exit_hctx_callback( + hctx: *mut bindings::blk_mq_hw_ctx, + _hctx_idx: core::ffi::c_uint, + ) { + let ptr = unsafe { (*hctx).driver_data }; + unsafe { T::HwData::from_foreign(ptr) }; + } + + unsafe extern "C" fn init_request_callback( + set: *mut bindings::blk_mq_tag_set, + rq: *mut bindings::request, + _hctx_idx: core::ffi::c_uint, + _numa_node: core::ffi::c_uint, + ) -> core::ffi::c_int { + from_result(|| { + // SAFETY: The tagset invariants guarantee that all requests are allocated with extra memory + // for the request data. + let pdu = unsafe { bindings::blk_mq_rq_to_pdu(rq) } as *mut T::RequestData; + let tagset_data = unsafe { T::TagSetData::borrow((*set).driver_data) }; + + let v = T::new_request_data(tagset_data)?; + + // SAFETY: `pdu` memory is valid, as it was allocated by the caller. + unsafe { pdu.write(v) }; + + let tagset_data = unsafe { T::TagSetData::borrow((*set).driver_data) }; + // SAFETY: `pdu` memory is valid and properly initialised. + T::init_request_data(tagset_data, unsafe { Pin::new_unchecked(&mut *pdu) })?; + + Ok(0) + }) + } + + unsafe extern "C" fn exit_request_callback( + _set: *mut bindings::blk_mq_tag_set, + rq: *mut bindings::request, + _hctx_idx: core::ffi::c_uint, + ) { + // SAFETY: The tagset invariants guarantee that all requests are allocated with extra memory + // for the request data. + let pdu = unsafe { bindings::blk_mq_rq_to_pdu(rq) } as *mut T::RequestData; + + // SAFETY: `pdu` is valid for read and write and is properly initialised. + unsafe { core::ptr::drop_in_place(pdu) }; + } + + unsafe extern "C" fn map_queues_callback(tag_set_ptr: *mut bindings::blk_mq_tag_set) { + let tag_set = unsafe { TagSetRef::from_ptr(tag_set_ptr) }; + T::map_queues(&tag_set); + } + + const VTABLE: bindings::blk_mq_ops = bindings::blk_mq_ops { + queue_rq: Some(Self::queue_rq_callback), + queue_rqs: None, + commit_rqs: Some(Self::commit_rqs_callback), + get_budget: None, + put_budget: None, + set_rq_budget_token: None, + get_rq_budget_token: None, + timeout: None, + poll: if T::HAS_POLL { + Some(Self::poll_callback) + } else { + None + }, + complete: Some(Self::complete_callback), + init_hctx: Some(Self::init_hctx_callback), + exit_hctx: Some(Self::exit_hctx_callback), + init_request: Some(Self::init_request_callback), + exit_request: Some(Self::exit_request_callback), + cleanup_rq: None, + busy: None, + map_queues: if T::HAS_MAP_QUEUES { + Some(Self::map_queues_callback) + } else { + None + }, + #[cfg(CONFIG_BLK_DEBUG_FS)] + show_rq: None, + }; + + pub(crate) const unsafe fn build() -> &'static bindings::blk_mq_ops { + &Self::VTABLE + } +} diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs new file mode 100644 index 000000000000..25c16ee0b1f7 --- /dev/null +++ b/rust/kernel/block/mq/raw_writer.rs @@ -0,0 +1,30 @@ +use core::fmt::{self, Write}; + +pub(crate) struct RawWriter { + ptr: *mut u8, + len: usize, +} + +impl RawWriter { + unsafe fn new(ptr: *mut u8, len: usize) -> Self { + Self { ptr, len } + } + + pub(crate) fn from_array<const N: usize>(a: &mut [core::ffi::c_char; N]) -> Self { + unsafe { Self::new(&mut a[0] as *mut _ as _, N) } + } +} + +impl Write for RawWriter { + fn write_str(&mut self, s: &str) -> fmt::Result { + let bytes = s.as_bytes(); + let len = bytes.len(); + if len > self.len { + return Err(fmt::Error); + } + unsafe { core::ptr::copy_nonoverlapping(&bytes[0], self.ptr, len) }; + self.ptr = unsafe { self.ptr.add(len) }; + self.len -= len; + Ok(()) + } +} diff --git a/rust/kernel/block/mq/request.rs b/rust/kernel/block/mq/request.rs new file mode 100644 index 000000000000..e95ae3fd71ad --- /dev/null +++ b/rust/kernel/block/mq/request.rs @@ -0,0 +1,71 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! This module provides a wrapper for the C `struct request` type. +//! +//! C header: [`include/linux/blk-mq.h`](../../include/linux/blk-mq.h) + +use crate::{ + bindings, + block::mq::Operations, + error::{Error, Result}, +}; +use core::marker::PhantomData; + +/// A wrapper around a blk-mq `struct request`. This represents an IO request. +pub struct Request<T: Operations> { + ptr: *mut bindings::request, + _p: PhantomData<T>, +} + +impl<T: Operations> Request<T> { + pub(crate) unsafe fn from_ptr(ptr: *mut bindings::request) -> Self { + Self { + ptr, + _p: PhantomData, + } + } + + /// Get the command identifier for the request + pub fn command(&self) -> u32 { + unsafe { (*self.ptr).cmd_flags & ((1 << bindings::REQ_OP_BITS) - 1) } + } + + /// Call this to indicate to the kernel that the request has been issued by the driver + pub fn start(&self) { + unsafe { bindings::blk_mq_start_request(self.ptr) }; + } + + /// Call this to indicate to the kernel that the request has been completed without errors + // TODO: Consume rq so that we can't use it after ending it? + pub fn end_ok(&self) { + unsafe { bindings::blk_mq_end_request(self.ptr, bindings::BLK_STS_OK as _) }; + } + + /// Call this to indicate to the kernel that the request completed with an error + pub fn end_err(&self, err: Error) { + unsafe { bindings::blk_mq_end_request(self.ptr, err.to_blk_status()) }; + } + + /// Call this to indicate that the request completed with the status indicated by `status` + pub fn end(&self, status: Result) { + if let Err(e) = status { + self.end_err(e); + } else { + self.end_ok(); + } + } + + /// Call this to schedule defered completion of the request + // TODO: Consume rq so that we can't use it after completing it? + pub fn complete(&self) { + if !unsafe { bindings::blk_mq_complete_request_remote(self.ptr) } { + T::complete(&unsafe { Self::from_ptr(self.ptr) }); + } + } + + /// Get the target sector for the request + #[inline(always)] + pub fn sector(&self) -> usize { + unsafe { (*self.ptr).__sector as usize } + } +} diff --git a/rust/kernel/block/mq/tag_set.rs b/rust/kernel/block/mq/tag_set.rs new file mode 100644 index 000000000000..d122db7f6d0e --- /dev/null +++ b/rust/kernel/block/mq/tag_set.rs @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! This module provides the `TagSet` struct to wrap the C `struct blk_mq_tag_set`. +//! +//! C header: [`include/linux/blk-mq.h`](../../include/linux/blk-mq.h) + +use crate::{ + bindings, + block::mq::{operations::OperationsVtable, Operations}, + error::{Error, Result}, + sync::Arc, + types::ForeignOwnable, +}; +use core::{cell::UnsafeCell, convert::TryInto, marker::PhantomData}; + +/// A wrapper for the C `struct blk_mq_tag_set` +pub struct TagSet<T: Operations> { + inner: UnsafeCell<bindings::blk_mq_tag_set>, + _p: PhantomData<T>, +} + +impl<T: Operations> TagSet<T> { + /// Try to create a new tag set + pub fn try_new( + nr_hw_queues: u32, + tagset_data: T::TagSetData, + num_tags: u32, + num_maps: u32, + ) -> Result<Arc<Self>> { + let tagset = Arc::try_new(Self { + inner: UnsafeCell::new(bindings::blk_mq_tag_set::default()), + _p: PhantomData, + })?; + + // SAFETY: We just allocated `tagset`, we know this is the only reference to it. + let inner = unsafe { &mut *tagset.inner.get() }; + + inner.ops = unsafe { OperationsVtable::<T>::build() }; + inner.nr_hw_queues = nr_hw_queues; + inner.timeout = 0; // 0 means default which is 30 * HZ in C + inner.numa_node = bindings::NUMA_NO_NODE; + inner.queue_depth = num_tags; + inner.cmd_size = core::mem::size_of::<T::RequestData>().try_into()?; + inner.flags = bindings::BLK_MQ_F_SHOULD_MERGE; + inner.driver_data = tagset_data.into_foreign() as _; + inner.nr_maps = num_maps; + + // SAFETY: `inner` points to valid and initialised memory. + let ret = unsafe { bindings::blk_mq_alloc_tag_set(inner) }; + if ret < 0 { + // SAFETY: We created `driver_data` above with `into_foreign` + unsafe { T::TagSetData::from_foreign(inner.driver_data) }; + return Err(Error::from_errno(ret)); + } + + Ok(tagset) + } + + /// Return the pointer to the wrapped `struct blk_mq_tag_set` + pub(crate) fn raw_tag_set(&self) -> *mut bindings::blk_mq_tag_set { + self.inner.get() + } +} + +impl<T: Operations> Drop for TagSet<T> { + fn drop(&mut self) { + let tagset_data = unsafe { (*self.inner.get()).driver_data }; + + // SAFETY: `inner` is valid and has been properly initialised during construction. + unsafe { bindings::blk_mq_free_tag_set(self.inner.get()) }; + + // SAFETY: `tagset_data` was created by a call to + // `ForeignOwnable::into_foreign` in `TagSet::try_new()` + unsafe { T::TagSetData::from_foreign(tagset_data) }; + } +} + +/// A tag set reference. Used to control lifetime and prevent drop of TagSet references passed to +/// `Operations::map_queues()` +pub struct TagSetRef { + ptr: *mut bindings::blk_mq_tag_set, +} + +impl TagSetRef { + pub(crate) unsafe fn from_ptr(tagset: *mut bindings::blk_mq_tag_set) -> Self { + Self { ptr: tagset } + } + + pub fn ptr(&self) -> *mut bindings::blk_mq_tag_set { + self.ptr + } +} diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs index 5f4114b30b94..421fef677321 100644 --- a/rust/kernel/error.rs +++ b/rust/kernel/error.rs @@ -107,6 +107,10 @@ impl Error { self.0 } + pub(crate) fn to_blk_status(self) -> bindings::blk_status_t { + unsafe { bindings::errno_to_blk_status(self.0) } + } + /// Returns the error encoded as a pointer. #[allow(dead_code)] pub(crate) fn to_ptr<T>(self) -> *mut T { diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 8bef6686504b..cd798d12d97c 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -34,6 +34,7 @@ extern crate self as kernel; #[cfg(not(test))] #[cfg(not(testlib))] mod allocator; +pub mod block; mod build_assert; pub mod error; pub mod init; -- 2.40.0
