From nobody Fri Oct 3 11:14:49 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3D2772F1FCD; Tue, 2 Sep 2025 09:55:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756806951; cv=none; b=AqaXyG+H7/LqZHLlkoFaNCVB3321EnLvXrkpdcsKaHURBT6YI3/STc9SehaEtcgEgqZ8reoCjryLlJxmdbL/ouEkSKXdj/zDN+ShDWjgmzY3nLTQvjY9QXAWhAFofEyGOetiLww6CsUl1J6WeIaS6vhv+KI3zxEBW3UBnZW0T3Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756806951; c=relaxed/simple; bh=fPtLqPDGStsMXbu60xANaWKwVC7jEMMSV/rPKwvnnWs=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=uxj9UK4Ulw0eHnIwDRUKT1sjV3HIwaqA/EM5as+0vapY2kU5E2gk+83HTw/WF9B6Ejd0hCtc6L5SIpmqygmB/ra7CIJycdnlYmAU2Tc0GkWUqO1G/wFnuJewz9EB7CQgnkvTUx4snzFQqI0/Hd6K3HBDlq9qg8cANXv5rNfzB0Y= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LyRyQTd5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LyRyQTd5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D87C8C4CEED; Tue, 2 Sep 2025 09:55:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756806950; bh=fPtLqPDGStsMXbu60xANaWKwVC7jEMMSV/rPKwvnnWs=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=LyRyQTd5T6Wle3MmyKyXP+17NWFoGzS2lAERi2pUecgpR45KymNoD72/Use7BmCyH LQqJD3Mx4m502vaLKgGqq9FNhOxRD3M5rx5UAS7IZhcrQ2SffOj+U2/MCm9YTTz7xt aWlXOVkqGUTryDSTSCqK63DjqVJrb56jLmOsFItZyKTUvZj9P9Jw+MFRCJvl8BTyxj p98Ic+R80CgK0N3u1L7dFe/gMA6Q48YjoeaXoFIPuZFjUBQsNxUvTe6DP6Hw+N6H3+ VlNqp0X2bF0ZvqQeX8bcOiKf4WpmYBpqNQOSeHwexa+CRxAX9VuVnyy1b5f9MTyFuK eIgqPKp1ExDxA== From: Andreas Hindborg Date: Tue, 02 Sep 2025 11:55:07 +0200 Subject: [PATCH v7 13/17] rnull: enable configuration via `configfs` Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250902-rnull-up-v6-16-v7-13-b5212cc89b98@kernel.org> References: <20250902-rnull-up-v6-16-v7-0-b5212cc89b98@kernel.org> In-Reply-To: <20250902-rnull-up-v6-16-v7-0-b5212cc89b98@kernel.org> To: Boqun Feng , Miguel Ojeda , Alex Gaynor , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich , Jens Axboe , Breno Leitao Cc: linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Hindborg , Daniel Almeida X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=10609; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=fPtLqPDGStsMXbu60xANaWKwVC7jEMMSV/rPKwvnnWs=; b=owEBbQKS/ZANAwAIAeG4Gj55KGN3AcsmYgBotr8FyuToaKcvyBqHvnv+l/O0AuUSsgJLPdAa2 de7guT4pWKJAjMEAAEIAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaLa/BQAKCRDhuBo+eShj d/jqD/9XU1SLZsKQeFDo+H8Uc5JZ2lZ01GWtIasmmKqamRB1E9//SNoQz1BV9HAu39Me2YNkA6v S+gtA7Iwp74qRGNkQMUdB+lIUBwP0yTtgqw7s3QB35MY1S/ZpR70L3UKSzahjSwmbG561KH6rAc 0g4cEtCTADBO6jybNO/kkSXeeJ9HW0oJ7YTmtlqDklX7caGjSGX4LFTmGi8oVrt09iNY5uSPWCW e5hgd6XAuesMF1SR949z7BW9PpQxSYx8lsx1uKA9H3Ynxj6wDGdX33TQ+h4q/Q5dYjv7bFG130h yOZdsETZV8I0YNtrAN6/aS+wGuVDkU6lNwmkVTviOohUb4ytiovcE0h9dM+D/sOzTW/z06y74AT uSqF5+xugGG8Rv9TDN9OTbYctpnHK/NA22RqXG997hUfLs4KFubxtVLh7xKgUGoX+hBbEXKlToX KKKqzm4OMdjrlAgV6a7bfUh+xb7t0RYaUcODwv/nzkMU5vkCxE4iGMv6rjplbb1mBqAouusTewa Yir/37aXUlCRO4Rn+tXTi3qOhVMx0M8x0zGxZn8J4/y/k8S5aHAFMjVIvQ3vYXQcgrvIyGAyt+L TiP2fq3lU5scPrs/+wZ63Tplf/Mm1RDu1cMbTagLZsj5/40Ue+rwW1zdC6jdQtuRqZULPTalhDC iO9m8c/i7vRBkYg== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 Allow rust null block devices to be configured and instantiated via `configfs`. Reviewed-by: Daniel Almeida Reviewed-by: Alice Ryhl Signed-off-by: Andreas Hindborg --- 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 @@ =20 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, Error> { + let item_type =3D configfs_attrs! { + container: configfs::Subsystem, + data: Config, + child: DeviceConfig, + attributes: [ + features: 0, + ], + }; + + kernel::configfs::Subsystem::new(c_str!("rnull"), item_type, try_pin_i= nit!(Config {})) +} + +#[pin_data] +pub(crate) struct Config {} + +#[vtable] +impl AttributeOperations<0> for Config { + type Data =3D Config; + + fn show(_this: &Config, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer =3D kernel::str::Formatter::new(page); + writer.write_str("blocksize,size,rotational\n")?; + Ok(writer.bytes_written()) + } +} + +#[vtable] +impl configfs::GroupOperations for Config { + type Child =3D DeviceConfig; + + fn make_group( + &self, + name: &CStr, + ) -> Result, Error>> { + let item_type =3D configfs_attrs! { + container: configfs::Group, + 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, +} + +#[pin_data] +struct DeviceConfigInner { + powered: bool, + name: CString, + block_size: u32, + rotational: bool, + capacity_mib: u64, + disk: Option>, +} + +#[vtable] +impl configfs::AttributeOperations<0> for DeviceConfig { + type Data =3D DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer =3D 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 =3D kstrtobool_bytes(page)?; + let mut guard =3D this.data.lock(); + + if !guard.powered && power_op { + guard.disk =3D Some(NullBlkDevice::new( + &guard.name, + guard.block_size, + guard.rotational, + guard.capacity_mib, + )?); + guard.powered =3D true; + } else if guard.powered && !power_op { + drop(guard.disk.take()); + guard.powered =3D false; + } + + Ok(()) + } +} + +#[vtable] +impl configfs::AttributeOperations<1> for DeviceConfig { + type Data =3D DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer =3D 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 =3D core::str::from_utf8(page)?.trim(); + let value =3D text.parse::().map_err(|_| EINVAL)?; + + GenDiskBuilder::validate_block_size(value)?; + this.data.lock().block_size =3D value; + Ok(()) + } +} + +#[vtable] +impl configfs::AttributeOperations<2> for DeviceConfig { + type Data =3D DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer =3D 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 =3D kstrtobool_bytes(page)?; + + Ok(()) + } +} + +#[vtable] +impl configfs::AttributeOperations<3> for DeviceConfig { + type Data =3D DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer =3D 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 =3D core::str::from_utf8(page)?.trim(); + let value =3D text.parse::().map_err(|_| EINVAL)?; + + this.data.lock().capacity_mib =3D 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 =20 //! 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; =20 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; =20 module! { type: NullBlkModule, @@ -35,33 +32,39 @@ #[pin_data] struct NullBlkModule { #[pin] - _disk: Mutex>, + configfs_subsystem: kernel::configfs::Subsystem, } =20 impl kernel::InPlaceModule for NullBlkModule { fn init(_module: &'static ThisModule) -> impl PinInit { pr_info!("Rust null_blk loaded\n"); =20 - // Use a immediately-called closure as a stable `try` block - let disk =3D /* try */ (|| { - let tagset =3D Arc::pin_init(TagSet::new(1, 256, 1), flags::GF= P_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(), }) } } =20 struct NullBlkDevice; =20 +impl NullBlkDevice { + fn new( + name: &CStr, + block_size: u32, + rotational: bool, + capacity_mib: u64, + ) -> Result> { + let tagset =3D 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_di= sk.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 { =20 /// 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..=3Dbindings::PAGE_SIZE as u32).contains(&size) || !size.= is_power_of_two() { Err(error::code::EINVAL) } else { --=20 2.47.2