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Date: Fri, 14 Jul 2023 15:49:15 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Qingsong Chen <changxian.cqs@...group.com>
Cc: linux-kernel@...r.kernel.org,
田洪亮 <tate.thl@...group.com>,
Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Wedson Almeida Filho <wedsonaf@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
rust-for-linux@...r.kernel.org
Subject: Re: [RFC PATCH 2/8] rust: kernel: add `request` related TargetOperations
> - Add `request` related and end_io TargetOperations.
> - Add a dummy `request` wrapper and `blk_status_t`.
>
> Signed-off-by: Qingsong Chen <changxian.cqs@...group.com>
> ---
> rust/kernel/device_mapper.rs | 199 +++++++++++++++++++++++++++++++++++
> 1 file changed, 199 insertions(+)
>
> diff --git a/rust/kernel/device_mapper.rs b/rust/kernel/device_mapper.rs
> index 28286b373b59..153bae3aad79 100644
> --- a/rust/kernel/device_mapper.rs
> +++ b/rust/kernel/device_mapper.rs
> @@ -31,6 +31,39 @@ pub trait TargetOperations: Sized {
> /// Map block IOs. Return [`MapState`] to indicate how to handle the `bio`
> /// later (end or resubmit).
> fn map(t: &mut Target<Self>, bio: Pin<&mut Bio>) -> MapState;
> +
> + /// Map `request`. Return [`MapState`] and the optional cloned `request`.
> + #[allow(unused)]
> + fn clone_and_map_rq<'a>(
> + t: &mut Target<Self>,
> + rq: Pin<&mut Request>,
> + map_ctx: &mut MapInfo,
> + ) -> (MapState, Option<Pin<&'a mut Request>>) {
> + unimplemented!()
Note that these should be implemented when you submit this as an actual
patch. (Not sure what you would do in this case, but throwing a panic is
not a good idea.) This also applies to all subsequent patches.
I think you might have done this, because you want the C side to choose
the default implementation. But it should also be possible to call these
from the Rust side.
--
Cheers,
Benno
> + }
> +
> + /// Release the cloned `request`.
> + #[allow(unused)]
> + fn release_clone_rq(rq: Pin<&mut Request>, map_ctx: &mut MapInfo) {
> + unimplemented!()
> + }
> +
> + /// End the `bio`. Return [`EndState`] and [`BlkStatus`].
> + #[allow(unused)]
> + fn end_io(t: &mut Target<Self>, bio: Pin<&mut Bio>) -> (EndState, BlkStatus) {
> + unimplemented!()
> + }
> +
> + /// End the `request`. Return [`EndState`].
> + #[allow(unused)]
> + fn rq_end_io(
> + t: &mut Target<Self>,
> + rq: Pin<&mut Request>,
> + map_ctx: &mut MapInfo,
> + err: BlkStatus,
> + ) -> EndState {
> + unimplemented!()
> + }
> }
>
> /// Wrap the kernel struct `target_type`.
> @@ -85,6 +118,18 @@ pub fn register<T: TargetOperations>(
> (HAS_CTR, ctr, dm_ctr_fn),
> (HAS_DTR, dtr, dm_dtr_fn),
> (HAS_MAP, map, dm_map_fn),
> + (
> + HAS_CLONE_AND_MAP_RQ,
> + clone_and_map_rq,
> + dm_clone_and_map_request_fn
> + ),
> + (
> + HAS_RELEASE_CLONE_RQ,
> + release_clone_rq,
> + dm_release_clone_request_fn
> + ),
> + (HAS_END_IO, end_io, dm_endio_fn),
> + (HAS_RQ_END_IO, rq_end_io, dm_request_endio_fn),
> );
>
> to_result(bindings::dm_register_target(tt))
> @@ -148,6 +193,64 @@ impl TargetType {
> T::map(t, bio) as _
> }
> }
> + unsafe extern "C" fn dm_clone_and_map_request_fn<T: TargetOperations>(
> + ti: *mut bindings::dm_target,
> + rq: *mut bindings::request,
> + map_context: *mut bindings::map_info,
> + clone: *mut *mut bindings::request,
> + ) -> core::ffi::c_int {
> + // SAFETY: the kernel should pass valid `dm_target`, `request`
> + // and `map_info` pointers.
> + unsafe {
> + let t = Target::borrow_mut(ti);
> + let rq = Request::from_raw(rq);
> + let map_ctx = MapInfo::borrow_mut(map_context);
> + let (map_state, rq_cloned) = T::clone_and_map_rq(t, rq, map_ctx);
> + *clone = rq_cloned.map_or(core::ptr::null_mut(), |rq| rq.opaque.get());
> + map_state as _
> + }
> + }
> + unsafe extern "C" fn dm_release_clone_request_fn<T: TargetOperations>(
> + clone: *mut bindings::request,
> + map_context: *mut bindings::map_info,
> + ) {
> + // SAFETY: the kernel should pass valid `request` and `map_info` pointers.
> + unsafe {
> + let rq = Request::from_raw(clone);
> + let map_ctx = MapInfo::borrow_mut(map_context);
> + T::release_clone_rq(rq, map_ctx);
> + }
> + }
> + unsafe extern "C" fn dm_endio_fn<T: TargetOperations>(
> + ti: *mut bindings::dm_target,
> + bio: *mut bindings::bio,
> + error: *mut bindings::blk_status_t,
> + ) -> core::ffi::c_int {
> + // SAFETY: the kernel should pass valid `dm_target`, `bio` and
> + // `error` pointers.
> + unsafe {
> + let t = Target::borrow_mut(ti);
> + let bio = Bio::from_raw(bio);
> + let (end_state, blk_status) = T::end_io(t, bio);
> + *error = blk_status as _;
> + end_state as _
> + }
> + }
> + unsafe extern "C" fn dm_request_endio_fn<T: TargetOperations>(
> + ti: *mut bindings::dm_target,
> + clone: *mut bindings::request,
> + error: bindings::blk_status_t,
> + map_context: *mut bindings::map_info,
> + ) -> core::ffi::c_int {
> + // SAFETY: the kernel should pass valid `dm_target`, `request`
> + // and `map_info` pointers.
> + unsafe {
> + let t = Target::borrow_mut(ti);
> + let rq = Request::from_raw(clone);
> + let map_ctx = MapInfo::borrow_mut(map_context);
> + T::rq_end_io(t, rq, map_ctx, (error as u32).into()) as _
> + }
> + }
> }
>
> /// Wrap the kernel struct `dm_target`.
> @@ -305,6 +408,33 @@ pub enum MapState {
> Kill = bindings::DM_MAPIO_KILL,
> }
>
> +/// The return values of target end_io function.
> +#[repr(u32)]
> +pub enum EndState {
> + /// Ended successfully.
> + Done = bindings::DM_ENDIO_DONE,
> +
> + /// The io has still not completed (eg, multipath target might
> + /// want to requeue a failed io).
> + Incomplete = bindings::DM_ENDIO_INCOMPLETE,
> +
> + /// The target wants to requeue the io.
> + Requeue = bindings::DM_ENDIO_REQUEUE,
> +
> + /// The target wants to requeue the io after a delay.
> + DelayRequeue = bindings::DM_ENDIO_DELAY_REQUEUE,
> +}
> +
> +/// Wrap the c struct `map_info`.
> +pub struct MapInfo(Opaque<bindings::map_info>);
> +
> +impl MapInfo {
> + unsafe fn borrow_mut<'a>(ptr: *mut bindings::map_info) -> &'a mut Self {
> + // SAFETY: the caller should pass a valid `ptr`.
> + unsafe { &mut *(ptr as *mut Self) }
> + }
> +}
> +
> /// Wrap the `c_char` arguments, which yields `CStr`.
> pub struct Args {
> argc: core::ffi::c_uint,
> @@ -380,3 +510,72 @@ pub fn is_write(&self) -> bool {
> self.op_and_flags() & bindings::req_op_REQ_OP_WRITE != 0
> }
> }
> +
> +/// Wrap the kernel struct `request`.
> +///
> +/// Dummy.
> +#[pin_data]
> +pub struct Request {
> + #[pin]
> + opaque: Opaque<bindings::request>,
> +}
> +
> +impl Request {
> + unsafe fn from_raw<'a>(ptr: *mut bindings::request) -> Pin<&'a mut Self> {
> + // SAFETY: the caller should pass a valid `request` pointer.
> + unsafe { Pin::new_unchecked(&mut *(ptr as *mut Self)) }
> + }
> +}
> +
> +/// Wrap the block error status values (see [blk_status_t]).
> +///
> +/// [`blk_status_t`]: ../../../../include/linux/blk_types.h
> +#[repr(u32)]
> +#[allow(missing_docs)]
> +pub enum BlkStatus {
> + Ok,
> + NotSupp,
> + TimeOut,
> + NoSpc,
> + Transport,
> + Target,
> + Nexus,
> + Medium,
> + Protection,
> + Resource,
> + IoErr,
> + DmRequeue,
> + Again,
> + DevResource,
> + ZoneResource,
> + ZoneOpenResource,
> + ZoneActiveResource,
> + Offline,
> + Undefined,
> +}
> +
> +impl From<u32> for BlkStatus {
> + fn from(value: u32) -> Self {
> + match value {
> + 0 => Self::Ok,
> + 1 => Self::NotSupp,
> + 2 => Self::TimeOut,
> + 3 => Self::NoSpc,
> + 4 => Self::Transport,
> + 5 => Self::Target,
> + 6 => Self::Nexus,
> + 7 => Self::Medium,
> + 8 => Self::Protection,
> + 9 => Self::Resource,
> + 10 => Self::IoErr,
> + 11 => Self::DmRequeue,
> + 12 => Self::Again,
> + 13 => Self::DevResource,
> + 14 => Self::ZoneResource,
> + 15 => Self::ZoneOpenResource,
> + 16 => Self::ZoneActiveResource,
> + 17 => Self::Offline,
> + _ => Self::Undefined,
> + }
> + }
> +}
> --
> 2.40.1
>
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