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Message-Id: <20230503090708.2524310-11-nmi@metaspace.dk>
Date: Wed, 3 May 2023 11:07:07 +0200
From: Andreas Hindborg <nmi@...aspace.dk>
To: Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
Keith Busch <kbusch@...nel.org>,
Damien Le Moal <Damien.LeMoal@....com>,
Hannes Reinecke <hare@...e.de>,
lsf-pc@...ts.linux-foundation.org, rust-for-linux@...r.kernel.org,
linux-block@...r.kernel.org
Cc: Andreas Hindborg <a.hindborg@...sung.com>,
Matthew Wilcox <willy@...radead.org>,
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>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <nmi@...aspace.dk>,
linux-kernel@...r.kernel.org (open list), gost.dev@...sung.com
Subject: [RFC PATCH 10/11] rust: add null block driver
From: Andreas Hindborg <a.hindborg@...sung.com>
The driver is implemented entirely using safe Rust. This initial version
supports direct completion, read and write requests, blk-mq and optional memory
backing.
Signed-off-by: Andreas Hindborg <a.hindborg@...sung.com>
---
drivers/block/Kconfig | 4 +
drivers/block/Makefile | 4 +
drivers/block/rnull-helpers.c | 60 ++++++++++++
drivers/block/rnull.rs | 177 ++++++++++++++++++++++++++++++++++
scripts/Makefile.build | 2 +-
5 files changed, 246 insertions(+), 1 deletion(-)
create mode 100644 drivers/block/rnull-helpers.c
create mode 100644 drivers/block/rnull.rs
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index f79f20430ef7..644ef1bc7574 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -354,6 +354,10 @@ config VIRTIO_BLK
This is the virtual block driver for virtio. It can be used with
QEMU based VMMs (like KVM or Xen). Say Y or M.
+config BLK_DEV_RS_NULL
+ tristate "Rust null block driver"
+ depends on RUST
+
config BLK_DEV_RBD
tristate "Rados block device (RBD)"
depends on INET && BLOCK
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 101612cba303..cebbeece4bc2 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -9,6 +9,10 @@
# needed for trace events
ccflags-y += -I$(src)
+obj-$(CONFIG_BLK_DEV_RS_NULL) += rnull_mod.o
+rnull_mod-y := rnull-helpers.o rnull.o
+LLVM_LINK_FIX_drivers/block/rnull_mod.o := 1
+
obj-$(CONFIG_MAC_FLOPPY) += swim3.o
obj-$(CONFIG_BLK_DEV_SWIM) += swim_mod.o
obj-$(CONFIG_BLK_DEV_FD) += floppy.o
diff --git a/drivers/block/rnull-helpers.c b/drivers/block/rnull-helpers.c
new file mode 100644
index 000000000000..826f2773ed93
--- /dev/null
+++ b/drivers/block/rnull-helpers.c
@@ -0,0 +1,60 @@
+
+#include <linux/bio.h>
+
+__attribute__((always_inline))
+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);
+}
+
+__attribute__((always_inline)) void *rust_helper_kmap(struct page *page)
+{
+ return kmap(page);
+}
+
+__attribute__((always_inline)) void rust_helper_kunmap(struct page *page)
+{
+ return kunmap(page);
+}
+
+__attribute__((always_inline)) void *rust_helper_kmap_atomic(struct page *page)
+{
+ return kmap_atomic(page);
+}
+
+__attribute__((always_inline)) void rust_helper_kunmap_atomic(void* address)
+{
+ kunmap_atomic(address);
+}
+
+__attribute__((always_inline)) struct page *
+rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
+{
+ return alloc_pages(gfp_mask, order);
+}
+
+__attribute__((always_inline)) void rust_helper_spin_lock_irq(spinlock_t *lock)
+{
+ spin_lock_irq(lock);
+}
+
+__attribute__((always_inline)) void
+rust_helper_spin_unlock_irq(spinlock_t *lock)
+{
+ spin_unlock_irq(lock);
+}
+__attribute__((always_inline)) unsigned long
+rust_helper_spin_lock_irqsave(spinlock_t *lock)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(lock, flags);
+
+ return flags;
+}
+__attribute__((always_inline)) void
+rust_helper_spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
+{
+ spin_unlock_irqrestore(lock, flags);
+}
diff --git a/drivers/block/rnull.rs b/drivers/block/rnull.rs
new file mode 100644
index 000000000000..d95025664a60
--- /dev/null
+++ b/drivers/block/rnull.rs
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! This is a null block driver. It currently supports optional memory backing,
+//! blk-mq interface and direct completion. The driver is configured at module
+//! load time by parameters `memory_backed` and `capacity_mib`.
+
+use kernel::{
+ bindings,
+ block::{
+ bio::Segment,
+ mq::{self, GenDisk, Operations, TagSet},
+ },
+ error::Result,
+ macros::vtable,
+ new_mutex, new_spinlock,
+ pages::Pages,
+ pr_info,
+ prelude::*,
+ radix_tree::RadixTree,
+ sync::{Arc, Mutex, SpinLock},
+ types::ForeignOwnable,
+};
+
+module! {
+ type: NullBlkModule,
+ name: "rs_null_blk",
+ author: "Andreas Hindborg",
+ license: "GPL v2",
+ params: {
+ memory_backed: bool {
+ default: true,
+ permissions: 0,
+ description: "Use memory backing",
+ },
+ capacity_mib: u64 {
+ default: 4096,
+ permissions: 0,
+ description: "Device capacity in MiB",
+ },
+ },
+}
+
+struct NullBlkModule {
+ _disk: Pin<Box<Mutex<GenDisk<NullBlkDevice>>>>,
+}
+
+fn add_disk(tagset: Arc<TagSet<NullBlkDevice>>) -> Result<GenDisk<NullBlkDevice>> {
+ let tree = RadixTree::new()?;
+ let queue_data = Box::pin_init(new_spinlock!(tree, "rnullb:mem"))?;
+
+ let disk = GenDisk::try_new(tagset, queue_data)?;
+ disk.set_name(format_args!("rnullb{}", 0))?;
+ disk.set_capacity(*capacity_mib.read() << 11);
+ disk.set_queue_logical_block_size(4096);
+ disk.set_queue_physical_block_size(4096);
+ disk.set_rotational(false);
+ Ok(disk)
+}
+
+impl kernel::Module for NullBlkModule {
+ fn init(_module: &'static ThisModule) -> Result<Self> {
+ pr_info!("Rust null_blk loaded\n");
+ // Major device number?
+ let tagset = TagSet::try_new(1, (), 256, 1)?;
+ let disk = Box::pin_init(new_mutex!(add_disk(tagset)?, "nullb:disk"))?;
+
+ disk.lock().add()?;
+
+ Ok(Self { _disk: disk })
+ }
+}
+
+impl Drop for NullBlkModule {
+ fn drop(&mut self) {
+ pr_info!("Dropping rnullb\n");
+ }
+}
+
+struct NullBlkDevice;
+type Tree = kernel::radix_tree::RadixTree<Box<Pages<0>>>;
+type Data = Pin<Box<SpinLock<Tree>>>;
+
+impl NullBlkDevice {
+ #[inline(always)]
+ fn write(tree: &mut Tree, sector: usize, segment: &Segment<'_>) -> Result {
+ let idx = sector >> 3; // TODO: PAGE_SECTOR_SHIFT
+ let mut page = if let Some(page) = tree.get_mut(idx as u64) {
+ page
+ } else {
+ tree.try_insert(idx as u64, Box::try_new(Pages::new()?)?)?;
+ tree.get_mut(idx as u64).unwrap()
+ };
+
+ segment.copy_to_page_atomic(&mut page)?;
+
+ Ok(())
+ }
+
+ #[inline(always)]
+ fn read(tree: &mut Tree, sector: usize, segment: &mut Segment<'_>) -> Result {
+ let idx = sector >> 3; // TODO: PAGE_SECTOR_SHIFT
+ if let Some(page) = tree.get(idx as u64) {
+ segment.copy_from_page_atomic(page)?;
+ }
+
+ Ok(())
+ }
+
+ #[inline(never)]
+ fn transfer(
+ command: bindings::req_op,
+ tree: &mut Tree,
+ sector: usize,
+ segment: &mut Segment<'_>,
+ ) -> Result {
+ match command {
+ bindings::req_op_REQ_OP_WRITE => Self::write(tree, sector, segment)?,
+ bindings::req_op_REQ_OP_READ => Self::read(tree, sector, segment)?,
+ _ => (),
+ }
+ Ok(())
+ }
+}
+
+#[vtable]
+impl Operations for NullBlkDevice {
+ type RequestData = ();
+ type QueueData = Data;
+ type HwData = ();
+ type TagSetData = ();
+
+ fn new_request_data(
+ _tagset_data: <Self::TagSetData as ForeignOwnable>::Borrowed<'_>,
+ ) -> Result<Self::RequestData> {
+ Ok(())
+ }
+
+ #[inline(always)]
+ fn queue_rq(
+ _hw_data: <Self::HwData as ForeignOwnable>::Borrowed<'_>,
+ queue_data: <Self::QueueData as ForeignOwnable>::Borrowed<'_>,
+ rq: &mq::Request<Self>,
+ _is_last: bool,
+ ) -> Result {
+ rq.start();
+ if *memory_backed.read() {
+ let mut tree = queue_data.lock_irqsave();
+
+ let mut sector = rq.sector();
+ for bio in rq.bio_iter() {
+ for mut segment in bio.segment_iter() {
+ let _ = Self::transfer(rq.command(), &mut tree, sector, &mut segment);
+ sector += segment.len() >> 9; // TODO: SECTOR_SHIFT
+ }
+ }
+ }
+ rq.end_ok();
+ Ok(())
+ }
+
+ fn commit_rqs(
+ _hw_data: <Self::HwData as ForeignOwnable>::Borrowed<'_>,
+ _queue_data: <Self::QueueData as ForeignOwnable>::Borrowed<'_>,
+ ) {
+ }
+
+ fn complete(_rq: &mq::Request<Self>) {
+ //rq.end_ok();
+ }
+
+ fn init_hctx(
+ _tagset_data: <Self::TagSetData as ForeignOwnable>::Borrowed<'_>,
+ _hctx_idx: u32,
+ ) -> Result<Self::HwData> {
+ Ok(())
+ }
+}
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9f94fc83f086..94127fc3cf77 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE
# Compile Rust sources (.rs)
# ---------------------------------------------------------------------------
-rust_allowed_features := core_ffi_c,explicit_generic_args_with_impl_trait,new_uninit,pin_macro
+rust_allowed_features := core_ffi_c,explicit_generic_args_with_impl_trait,new_uninit,pin_macro,allocator_api
rust_common_cmd = \
RUST_MODFILE=$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \
--
2.40.0
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