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-rw-r--r--rust/kernel/block/mq.rs14
-rw-r--r--rust/kernel/block/mq/gen_disk.rs56
-rw-r--r--rust/kernel/block/mq/operations.rs65
-rw-r--r--rust/kernel/block/mq/raw_writer.rs54
-rw-r--r--rust/kernel/block/mq/request.rs21
5 files changed, 124 insertions, 86 deletions
diff --git a/rust/kernel/block/mq.rs b/rust/kernel/block/mq.rs
index 61ea35bba7d5..637018ead0ab 100644
--- a/rust/kernel/block/mq.rs
+++ b/rust/kernel/block/mq.rs
@@ -69,27 +69,33 @@
//!
//! #[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: ()) {}
+//!
+//! fn complete(rq: ARef<Request<Self>>) {
+//! Request::end_ok(rq)
+//! .map_err(|_e| kernel::error::code::EIO)
+//! .expect("Fatal error - expected to be able to end request");
+//! }
//! }
//!
//! 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(fmt!("myblk"), tagset)?;
+//! .build(fmt!("myblk"), tagset, ())?;
//!
//! # Ok::<(), kernel::error::Error>(())
//! ```
pub mod gen_disk;
mod operations;
-mod raw_writer;
mod request;
mod tag_set;
diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
index be92d0e5f031..1ce815c8cdab 100644
--- a/rust/kernel/block/mq/gen_disk.rs
+++ b/rust/kernel/block/mq/gen_disk.rs
@@ -5,10 +5,17 @@
//! C header: [`include/linux/blkdev.h`](srctree/include/linux/blkdev.h)
//! C header: [`include/linux/blk-mq.h`](srctree/include/linux/blk-mq.h)
-use crate::block::mq::{raw_writer::RawWriter, Operations, TagSet};
-use crate::fmt::{self, Write};
-use crate::{bindings, error::from_err_ptr, error::Result, sync::Arc};
-use crate::{error, static_lock_class};
+use crate::{
+ bindings,
+ block::mq::{Operations, TagSet},
+ error::{self, from_err_ptr, Result},
+ fmt::{self, Write},
+ prelude::*,
+ static_lock_class,
+ str::NullTerminatedFormatter,
+ sync::Arc,
+ types::{ForeignOwnable, ScopeGuard},
+};
/// A builder for [`GenDisk`].
///
@@ -45,7 +52,7 @@ impl GenDiskBuilder {
/// Validate block size by verifying that it is between 512 and `PAGE_SIZE`,
/// and that it is a power of two.
- fn validate_block_size(size: u32) -> Result {
+ pub fn validate_block_size(size: u32) -> Result {
if !(512..=bindings::PAGE_SIZE as u32).contains(&size) || !size.is_power_of_two() {
Err(error::code::EINVAL)
} else {
@@ -92,7 +99,14 @@ impl GenDiskBuilder {
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() };
@@ -107,7 +121,7 @@ impl GenDiskBuilder {
bindings::__blk_mq_alloc_disk(
tagset.raw_tag_set(),
&mut lim,
- core::ptr::null_mut(),
+ data,
static_lock_class!().as_ptr(),
)
})?;
@@ -139,14 +153,14 @@ impl GenDiskBuilder {
// SAFETY: `gendisk` is a valid pointer as we initialized it above
unsafe { (*gendisk).fops = &TABLE };
- let mut raw_writer = RawWriter::from_array(
+ let mut writer = NullTerminatedFormatter::new(
// SAFETY: `gendisk` points to a valid and initialized instance. We
// have exclusive access, since the disk is not added to the VFS
// yet.
unsafe { &mut (*gendisk).disk_name },
- )?;
- raw_writer.write_fmt(name)?;
- raw_writer.write_char('\0')?;
+ )
+ .ok_or(EINVAL)?;
+ writer.write_fmt(name)?;
// SAFETY: `gendisk` points to a valid and initialized instance of
// `struct gendisk`. `set_capacity` takes a lock to synchronize this
@@ -161,8 +175,12 @@ impl GenDiskBuilder {
},
)?;
+ 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,
@@ -174,9 +192,10 @@ impl GenDiskBuilder {
///
/// # 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<T: Operations> {
_tagset: Arc<TagSet<T>>,
gendisk: *mut bindings::gendisk,
@@ -188,9 +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) });
}
}
diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/operations.rs
index c0f95a9419c4..f91a1719886c 100644
--- a/rust/kernel/block/mq/operations.rs
+++ b/rust/kernel/block/mq/operations.rs
@@ -6,15 +6,16 @@
use crate::{
bindings,
- block::mq::request::RequestDataWrapper,
- block::mq::Request,
+ block::mq::{request::RequestDataWrapper, Request},
error::{from_result, Result},
prelude::*,
sync::Refcount,
- types::ARef,
+ types::{ARef, ForeignOwnable},
};
use core::marker::PhantomData;
+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
@@ -27,12 +28,23 @@ use core::marker::PhantomData;
/// [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 when the request is completed.
+ fn complete(rq: ARef<Request<Self>>);
/// Called by the kernel to poll the device for completed requests. Only
/// used for poll queues.
@@ -71,7 +83,7 @@ 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
@@ -89,10 +101,20 @@ 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.
@@ -111,18 +133,35 @@ 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
- /// implemented, and there is no way to exercise this code path.
+ /// This function is called by the C kernel. A pointer to this function is
+ /// installed in the `blk_mq_ops` vtable for the driver.
///
/// # Safety
///
- /// This function may only be called by blk-mq C infrastructure.
- unsafe extern "C" fn complete_callback(_rq: *mut bindings::request) {}
+ /// This function may only be called by blk-mq C infrastructure. `rq` must
+ /// point to a valid request that has been marked as completed. The pointee
+ /// of `rq` must be valid for write for the duration of this function.
+ unsafe extern "C" fn complete_callback(rq: *mut bindings::request) {
+ // SAFETY: This function can only be dispatched through
+ // `Request::complete`. We leaked a refcount then which we pick back up
+ // now.
+ let aref = unsafe { Request::aref_from_raw(rq) };
+ T::complete(aref);
+ }
/// This function is called by the C kernel. A pointer to this function is
/// installed in the `blk_mq_ops` vtable for the driver.
diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
deleted file mode 100644
index d311e24e2595..000000000000
--- a/rust/kernel/block/mq/raw_writer.rs
+++ /dev/null
@@ -1,54 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-use crate::error::Result;
-use crate::fmt::{self, Write};
-use crate::prelude::EINVAL;
-
-/// A mutable reference to a byte buffer where a string can be written into.
-///
-/// # Invariants
-///
-/// `buffer` is always null terminated.
-pub(crate) struct RawWriter<'a> {
- buffer: &'a mut [u8],
- pos: usize,
-}
-
-impl<'a> RawWriter<'a> {
- /// Create a new `RawWriter` instance.
- fn new(buffer: &'a mut [u8]) -> Result<RawWriter<'a>> {
- *(buffer.last_mut().ok_or(EINVAL)?) = 0;
-
- // INVARIANT: We null terminated the buffer above.
- Ok(Self { buffer, pos: 0 })
- }
-
- pub(crate) fn from_array<const N: usize>(
- a: &'a mut [crate::ffi::c_char; N],
- ) -> Result<RawWriter<'a>> {
- Self::new(
- // SAFETY: the buffer of `a` is valid for read and write as `u8` for
- // at least `N` bytes.
- unsafe { core::slice::from_raw_parts_mut(a.as_mut_ptr().cast::<u8>(), N) },
- )
- }
-}
-
-impl Write for RawWriter<'_> {
- fn write_str(&mut self, s: &str) -> fmt::Result {
- let bytes = s.as_bytes();
- let len = bytes.len();
-
- // We do not want to overwrite our null terminator
- if self.pos + len > self.buffer.len() - 1 {
- return Err(fmt::Error);
- }
-
- // INVARIANT: We are not overwriting the last byte
- self.buffer[self.pos..self.pos + len].copy_from_slice(bytes);
-
- self.pos += len;
-
- Ok(())
- }
-}
diff --git a/rust/kernel/block/mq/request.rs b/rust/kernel/block/mq/request.rs
index f62a376dc313..c5f1f6b1ccfb 100644
--- a/rust/kernel/block/mq/request.rs
+++ b/rust/kernel/block/mq/request.rs
@@ -53,7 +53,7 @@ use core::{marker::PhantomData, ptr::NonNull};
/// [`struct request`]: srctree/include/linux/blk-mq.h
///
#[repr(transparent)]
-pub struct Request<T: Operations>(Opaque<bindings::request>, PhantomData<T>);
+pub struct Request<T>(Opaque<bindings::request>, PhantomData<T>);
impl<T: Operations> Request<T> {
/// Create an [`ARef<Request>`] from a [`struct request`] pointer.
@@ -138,6 +138,23 @@ impl<T: Operations> Request<T> {
Ok(())
}
+ /// Complete the request by scheduling `Operations::complete` for
+ /// execution.
+ ///
+ /// The function may be scheduled locally, via SoftIRQ or remotely via IPMI.
+ /// See `blk_mq_complete_request_remote` in [`blk-mq.c`] for details.
+ ///
+ /// [`blk-mq.c`]: srctree/block/blk-mq.c
+ pub fn complete(this: ARef<Self>) {
+ let ptr = ARef::into_raw(this).cast::<bindings::request>().as_ptr();
+ // SAFETY: By type invariant, `self.0` is a valid `struct request`
+ if !unsafe { bindings::blk_mq_complete_request_remote(ptr) } {
+ // SAFETY: We released a refcount above that we can reclaim here.
+ let this = unsafe { Request::aref_from_raw(ptr) };
+ T::complete(this);
+ }
+ }
+
/// Return a pointer to the [`RequestDataWrapper`] stored in the private area
/// of the request structure.
///
@@ -151,7 +168,7 @@ impl<T: Operations> Request<T> {
// valid allocation.
let wrapper_ptr =
unsafe { bindings::blk_mq_rq_to_pdu(request_ptr).cast::<RequestDataWrapper>() };
- // SAFETY: By C API contract, wrapper_ptr points to a valid allocation
+ // SAFETY: By C API contract, `wrapper_ptr` points to a valid allocation
// and is not null.
unsafe { NonNull::new_unchecked(wrapper_ptr) }
}
generated by cgit v1.2.3 (git 2.46.0) at 2025-10-03 01:57:44 +0000