Allow rust null block devices to be configured and instantiated via
`configfs`.
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
drivers/block/rnull/Kconfig | 2 +-
drivers/block/rnull/configfs.rs | 207 +++++++++++++++++++++++++++++++++++++++
drivers/block/rnull/rnull.rs | 59 +++++------
rust/kernel/block/mq/gen_disk.rs | 2 +-
4 files changed, 240 insertions(+), 30 deletions(-)
diff --git a/drivers/block/rnull/Kconfig b/drivers/block/rnull/Kconfig
index 6dc5aff96bf4..7bc5b376c128 100644
--- a/drivers/block/rnull/Kconfig
+++ b/drivers/block/rnull/Kconfig
@@ -4,7 +4,7 @@
config BLK_DEV_RUST_NULL
tristate "Rust null block driver (Experimental)"
- depends on RUST
+ depends on RUST && CONFIGFS_FS
help
This is the Rust implementation of the null block driver. Like
the C version, the driver allows the user to create virutal block
diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs
new file mode 100644
index 000000000000..46710a1e1af4
--- /dev/null
+++ b/drivers/block/rnull/configfs.rs
@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0
+
+use super::{NullBlkDevice, THIS_MODULE};
+use core::fmt::Write;
+use kernel::{
+ block::mq::gen_disk::{GenDisk, GenDiskBuilder},
+ c_str,
+ configfs::{self, AttributeOperations},
+ configfs_attrs, new_mutex,
+ page::PAGE_SIZE,
+ prelude::*,
+ str::{kstrtobool_bytes, CString},
+ sync::Mutex,
+};
+use pin_init::PinInit;
+
+pub(crate) fn subsystem() -> impl PinInit<kernel::configfs::Subsystem<Config>, Error> {
+ let item_type = configfs_attrs! {
+ container: configfs::Subsystem<Config>,
+ data: Config,
+ child: DeviceConfig,
+ attributes: [
+ features: 0,
+ ],
+ };
+
+ kernel::configfs::Subsystem::new(c_str!("rnull"), item_type, try_pin_init!(Config {}))
+}
+
+#[pin_data]
+pub(crate) struct Config {}
+
+#[vtable]
+impl AttributeOperations<0> for Config {
+ type Data = Config;
+
+ fn show(_this: &Config, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ let mut writer = kernel::str::Formatter::new(page);
+ writer.write_str("blocksize,size,rotational\n")?;
+ Ok(writer.bytes_written())
+ }
+}
+
+#[vtable]
+impl configfs::GroupOperations for Config {
+ type Child = DeviceConfig;
+
+ fn make_group(
+ &self,
+ name: &CStr,
+ ) -> Result<impl PinInit<configfs::Group<DeviceConfig>, Error>> {
+ let item_type = configfs_attrs! {
+ container: configfs::Group<DeviceConfig>,
+ data: DeviceConfig,
+ attributes: [
+ // Named for compatibility with C null_blk
+ power: 0,
+ blocksize: 1,
+ rotational: 2,
+ size: 3,
+ ],
+ };
+
+ Ok(configfs::Group::new(
+ name.try_into()?,
+ item_type,
+ // TODO: cannot coerce new_mutex!() to impl PinInit<_, Error>, so put mutex inside
+ try_pin_init!( DeviceConfig {
+ data <- new_mutex!(DeviceConfigInner {
+ powered: false,
+ block_size: 4096,
+ rotational: false,
+ disk: None,
+ capacity_mib: 4096,
+ name: name.try_into()?,
+ }),
+ }),
+ ))
+ }
+}
+
+#[pin_data]
+pub(crate) struct DeviceConfig {
+ #[pin]
+ data: Mutex<DeviceConfigInner>,
+}
+
+#[pin_data]
+struct DeviceConfigInner {
+ powered: bool,
+ name: CString,
+ block_size: u32,
+ rotational: bool,
+ capacity_mib: u64,
+ disk: Option<GenDisk<NullBlkDevice>>,
+}
+
+#[vtable]
+impl configfs::AttributeOperations<0> for DeviceConfig {
+ type Data = DeviceConfig;
+
+ fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ let mut writer = kernel::str::Formatter::new(page);
+
+ if this.data.lock().powered {
+ writer.write_str("1\n")?;
+ } else {
+ writer.write_str("0\n")?;
+ }
+
+ Ok(writer.bytes_written())
+ }
+
+ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+ let power_op = kstrtobool_bytes(page)?;
+ let mut guard = this.data.lock();
+
+ if !guard.powered && power_op {
+ guard.disk = Some(NullBlkDevice::new(
+ &guard.name,
+ guard.block_size,
+ guard.rotational,
+ guard.capacity_mib,
+ )?);
+ guard.powered = true;
+ } else if guard.powered && !power_op {
+ drop(guard.disk.take());
+ guard.powered = false;
+ }
+
+ Ok(())
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<1> for DeviceConfig {
+ type Data = DeviceConfig;
+
+ fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ let mut writer = kernel::str::Formatter::new(page);
+ writer.write_fmt(fmt!("{}\n", this.data.lock().block_size))?;
+ Ok(writer.bytes_written())
+ }
+
+ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+ if this.data.lock().powered {
+ return Err(EBUSY);
+ }
+
+ let text = core::str::from_utf8(page)?.trim();
+ let value = text.parse::<u32>().map_err(|_| EINVAL)?;
+
+ GenDiskBuilder::validate_block_size(value)?;
+ this.data.lock().block_size = value;
+ Ok(())
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<2> for DeviceConfig {
+ type Data = DeviceConfig;
+
+ fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ let mut writer = kernel::str::Formatter::new(page);
+
+ if this.data.lock().rotational {
+ writer.write_str("1\n")?;
+ } else {
+ writer.write_str("0\n")?;
+ }
+
+ Ok(writer.bytes_written())
+ }
+
+ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+ if this.data.lock().powered {
+ return Err(EBUSY);
+ }
+
+ this.data.lock().rotational = kstrtobool_bytes(page)?;
+
+ Ok(())
+ }
+}
+
+#[vtable]
+impl configfs::AttributeOperations<3> for DeviceConfig {
+ type Data = DeviceConfig;
+
+ fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
+ let mut writer = kernel::str::Formatter::new(page);
+ writer.write_fmt(fmt!("{}\n", this.data.lock().capacity_mib))?;
+ Ok(writer.bytes_written())
+ }
+
+ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
+ if this.data.lock().powered {
+ return Err(EBUSY);
+ }
+
+ let text = core::str::from_utf8(page)?.trim();
+ let value = text.parse::<u64>().map_err(|_| EINVAL)?;
+
+ this.data.lock().capacity_mib = value;
+ Ok(())
+ }
+}
diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs
index d07e76ae2c13..8690ff5f974f 100644
--- a/drivers/block/rnull/rnull.rs
+++ b/drivers/block/rnull/rnull.rs
@@ -1,28 +1,25 @@
// SPDX-License-Identifier: GPL-2.0
//! This is a Rust implementation of the C null block driver.
-//!
-//! Supported features:
-//!
-//! - blk-mq interface
-//! - direct completion
-//! - block size 4k
-//!
-//! The driver is not configurable.
+
+mod configfs;
use kernel::{
- alloc::flags,
- block::mq::{
+ block::{
self,
- gen_disk::{self, GenDisk},
- Operations, TagSet,
+ mq::{
+ self,
+ gen_disk::{self, GenDisk},
+ Operations, TagSet,
+ },
},
error::Result,
- new_mutex, pr_info,
+ pr_info,
prelude::*,
- sync::{Arc, Mutex},
+ sync::Arc,
types::ARef,
};
+use pin_init::PinInit;
module! {
type: NullBlkModule,
@@ -35,33 +32,39 @@
#[pin_data]
struct NullBlkModule {
#[pin]
- _disk: Mutex<GenDisk<NullBlkDevice>>,
+ configfs_subsystem: kernel::configfs::Subsystem<configfs::Config>,
}
impl kernel::InPlaceModule for NullBlkModule {
fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
pr_info!("Rust null_blk loaded\n");
- // Use a immediately-called closure as a stable `try` block
- let disk = /* try */ (|| {
- let tagset = Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?;
-
- gen_disk::GenDiskBuilder::new()
- .capacity_sectors(4096 << 11)
- .logical_block_size(4096)?
- .physical_block_size(4096)?
- .rotational(false)
- .build(format_args!("rnullb{}", 0), tagset)
- })();
-
try_pin_init!(Self {
- _disk <- new_mutex!(disk?, "nullb:disk"),
+ configfs_subsystem <- configfs::subsystem(),
})
}
}
struct NullBlkDevice;
+impl NullBlkDevice {
+ fn new(
+ name: &CStr,
+ block_size: u32,
+ rotational: bool,
+ capacity_mib: u64,
+ ) -> Result<GenDisk<Self>> {
+ let tagset = Arc::pin_init(TagSet::new(1, 256, 1), GFP_KERNEL)?;
+
+ gen_disk::GenDiskBuilder::new()
+ .capacity_sectors(capacity_mib << (20 - block::SECTOR_SHIFT))
+ .logical_block_size(block_size)?
+ .physical_block_size(block_size)?
+ .rotational(rotational)
+ .build(fmt!("{}", name.to_str()?), tagset)
+ }
+}
+
#[vtable]
impl Operations for NullBlkDevice {
#[inline(always)]
diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs
index 20f1d46c774d..6b1b846874db 100644
--- a/rust/kernel/block/mq/gen_disk.rs
+++ b/rust/kernel/block/mq/gen_disk.rs
@@ -51,7 +51,7 @@ pub fn rotational(mut self, rotational: bool) -> Self {
/// 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 {
--
2.47.2
> On 22 Aug 2025, at 09:14, Andreas Hindborg <a.hindborg@kernel.org> wrote: > > Allow rust null block devices to be configured and instantiated via > `configfs`. > > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org> > --- > drivers/block/rnull/Kconfig | 2 +- > drivers/block/rnull/configfs.rs | 207 +++++++++++++++++++++++++++++++++++++++ > drivers/block/rnull/rnull.rs | 59 +++++------ > rust/kernel/block/mq/gen_disk.rs | 2 +- > 4 files changed, 240 insertions(+), 30 deletions(-) > > diff --git a/drivers/block/rnull/Kconfig b/drivers/block/rnull/Kconfig > index 6dc5aff96bf4..7bc5b376c128 100644 > --- a/drivers/block/rnull/Kconfig > +++ b/drivers/block/rnull/Kconfig > @@ -4,7 +4,7 @@ > > config BLK_DEV_RUST_NULL > tristate "Rust null block driver (Experimental)" > - depends on RUST > + depends on RUST && CONFIGFS_FS > help > This is the Rust implementation of the null block driver. Like > the C version, the driver allows the user to create virutal block > diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs > new file mode 100644 > index 000000000000..46710a1e1af4 > --- /dev/null > +++ b/drivers/block/rnull/configfs.rs > @@ -0,0 +1,207 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +use super::{NullBlkDevice, THIS_MODULE}; > +use core::fmt::Write; > +use kernel::{ > + block::mq::gen_disk::{GenDisk, GenDiskBuilder}, > + c_str, > + configfs::{self, AttributeOperations}, > + configfs_attrs, new_mutex, > + page::PAGE_SIZE, > + prelude::*, > + str::{kstrtobool_bytes, CString}, > + sync::Mutex, > +}; > +use pin_init::PinInit; > + > +pub(crate) fn subsystem() -> impl PinInit<kernel::configfs::Subsystem<Config>, Error> { > + let item_type = configfs_attrs! { > + container: configfs::Subsystem<Config>, > + data: Config, > + child: DeviceConfig, > + attributes: [ > + features: 0, > + ], > + }; > + > + kernel::configfs::Subsystem::new(c_str!("rnull"), item_type, try_pin_init!(Config {})) > +} > + > +#[pin_data] > +pub(crate) struct Config {} > + > +#[vtable] > +impl AttributeOperations<0> for Config { > + type Data = Config; > + > + fn show(_this: &Config, page: &mut [u8; PAGE_SIZE]) -> Result<usize> { > + let mut writer = kernel::str::Formatter::new(page); > + writer.write_str("blocksize,size,rotational\n")?; > + Ok(writer.bytes_written()) > + } > +} > + > +#[vtable] > +impl configfs::GroupOperations for Config { > + type Child = DeviceConfig; > + > + fn make_group( > + &self, > + name: &CStr, > + ) -> Result<impl PinInit<configfs::Group<DeviceConfig>, Error>> { > + let item_type = configfs_attrs! { > + container: configfs::Group<DeviceConfig>, > + data: DeviceConfig, > + attributes: [ > + // Named for compatibility with C null_blk > + power: 0, > + blocksize: 1, > + rotational: 2, > + size: 3, > + ], > + }; > + > + Ok(configfs::Group::new( > + name.try_into()?, > + item_type, > + // TODO: cannot coerce new_mutex!() to impl PinInit<_, Error>, so put mutex inside > + try_pin_init!( DeviceConfig { > + data <- new_mutex!(DeviceConfigInner { > + powered: false, > + block_size: 4096, > + rotational: false, > + disk: None, > + capacity_mib: 4096, > + name: name.try_into()?, > + }), > + }), > + )) > + } > +} > + > +#[pin_data] > +pub(crate) struct DeviceConfig { > + #[pin] > + data: Mutex<DeviceConfigInner>, > +} > + > +#[pin_data] > +struct DeviceConfigInner { > + powered: bool, > + name: CString, > + block_size: u32, > + rotational: bool, > + capacity_mib: u64, > + disk: Option<GenDisk<NullBlkDevice>>, > +} > + > +#[vtable] > +impl configfs::AttributeOperations<0> for DeviceConfig { > + type Data = DeviceConfig; > + > + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> { > + let mut writer = kernel::str::Formatter::new(page); > + > + if this.data.lock().powered { > + writer.write_str("1\n")?; > + } else { > + writer.write_str("0\n")?; > + } > + > + Ok(writer.bytes_written()) > + } > + > + fn store(this: &DeviceConfig, page: &[u8]) -> Result { > + let power_op = kstrtobool_bytes(page)?; > + let mut guard = this.data.lock(); > + > + if !guard.powered && power_op { > + guard.disk = Some(NullBlkDevice::new( > + &guard.name, > + guard.block_size, > + guard.rotational, > + guard.capacity_mib, > + )?); > + guard.powered = true; > + } else if guard.powered && !power_op { > + drop(guard.disk.take()); > + guard.powered = false; > + } > + > + Ok(()) > + } > +} > + > +#[vtable] > +impl configfs::AttributeOperations<1> for DeviceConfig { > + type Data = DeviceConfig; > + > + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> { > + let mut writer = kernel::str::Formatter::new(page); > + writer.write_fmt(fmt!("{}\n", this.data.lock().block_size))?; > + Ok(writer.bytes_written()) > + } > + > + fn store(this: &DeviceConfig, page: &[u8]) -> Result { > + if this.data.lock().powered { > + return Err(EBUSY); > + } > + > + let text = core::str::from_utf8(page)?.trim(); > + let value = text.parse::<u32>().map_err(|_| EINVAL)?; > + > + GenDiskBuilder::validate_block_size(value)?; > + this.data.lock().block_size = value; > + Ok(()) > + } > +} > + > +#[vtable] > +impl configfs::AttributeOperations<2> for DeviceConfig { > + type Data = DeviceConfig; > + > + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> { > + let mut writer = kernel::str::Formatter::new(page); > + > + if this.data.lock().rotational { > + writer.write_str("1\n")?; > + } else { > + writer.write_str("0\n")?; > + } > + > + Ok(writer.bytes_written()) > + } > + > + fn store(this: &DeviceConfig, page: &[u8]) -> Result { > + if this.data.lock().powered { > + return Err(EBUSY); > + } > + > + this.data.lock().rotational = kstrtobool_bytes(page)?; > + > + Ok(()) > + } > +} > + > +#[vtable] > +impl configfs::AttributeOperations<3> for DeviceConfig { > + type Data = DeviceConfig; > + > + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> { > + let mut writer = kernel::str::Formatter::new(page); > + writer.write_fmt(fmt!("{}\n", this.data.lock().capacity_mib))?; > + Ok(writer.bytes_written()) > + } > + > + fn store(this: &DeviceConfig, page: &[u8]) -> Result { > + if this.data.lock().powered { > + return Err(EBUSY); > + } > + > + let text = core::str::from_utf8(page)?.trim(); > + let value = text.parse::<u64>().map_err(|_| EINVAL)?; > + > + this.data.lock().capacity_mib = value; > + Ok(()) > + } > +} > diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs > index d07e76ae2c13..8690ff5f974f 100644 > --- a/drivers/block/rnull/rnull.rs > +++ b/drivers/block/rnull/rnull.rs > @@ -1,28 +1,25 @@ > // SPDX-License-Identifier: GPL-2.0 > > //! This is a Rust implementation of the C null block driver. > -//! > -//! Supported features: > -//! > -//! - blk-mq interface > -//! - direct completion > -//! - block size 4k > -//! > -//! The driver is not configurable. > + > +mod configfs; > > use kernel::{ > - alloc::flags, > - block::mq::{ > + block::{ > self, > - gen_disk::{self, GenDisk}, > - Operations, TagSet, > + mq::{ > + self, > + gen_disk::{self, GenDisk}, > + Operations, TagSet, > + }, > }, > error::Result, > - new_mutex, pr_info, > + pr_info, > prelude::*, > - sync::{Arc, Mutex}, > + sync::Arc, > types::ARef, > }; > +use pin_init::PinInit; > > module! { > type: NullBlkModule, > @@ -35,33 +32,39 @@ > #[pin_data] > struct NullBlkModule { > #[pin] > - _disk: Mutex<GenDisk<NullBlkDevice>>, > + configfs_subsystem: kernel::configfs::Subsystem<configfs::Config>, > } > > impl kernel::InPlaceModule for NullBlkModule { > fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> { > pr_info!("Rust null_blk loaded\n"); > > - // Use a immediately-called closure as a stable `try` block > - let disk = /* try */ (|| { > - let tagset = Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; > - > - gen_disk::GenDiskBuilder::new() > - .capacity_sectors(4096 << 11) > - .logical_block_size(4096)? > - .physical_block_size(4096)? > - .rotational(false) > - .build(format_args!("rnullb{}", 0), tagset) > - })(); > - > try_pin_init!(Self { > - _disk <- new_mutex!(disk?, "nullb:disk"), > + configfs_subsystem <- configfs::subsystem(), > }) > } > } > > struct NullBlkDevice; > > +impl NullBlkDevice { > + fn new( > + name: &CStr, > + block_size: u32, > + rotational: bool, > + capacity_mib: u64, > + ) -> Result<GenDisk<Self>> { > + let tagset = Arc::pin_init(TagSet::new(1, 256, 1), GFP_KERNEL)?; > + > + gen_disk::GenDiskBuilder::new() > + .capacity_sectors(capacity_mib << (20 - block::SECTOR_SHIFT)) > + .logical_block_size(block_size)? > + .physical_block_size(block_size)? > + .rotational(rotational) > + .build(fmt!("{}", name.to_str()?), tagset) > + } > +} > + > #[vtable] > impl Operations for NullBlkDevice { > #[inline(always)] > diff --git a/rust/kernel/block/mq/gen_disk.rs b/rust/kernel/block/mq/gen_disk.rs > index 20f1d46c774d..6b1b846874db 100644 > --- a/rust/kernel/block/mq/gen_disk.rs > +++ b/rust/kernel/block/mq/gen_disk.rs > @@ -51,7 +51,7 @@ pub fn rotational(mut self, rotational: bool) -> Self { > > /// 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 { > > -- > 2.47.2 > > > Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
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