From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- drivers/block/rnull/configfs.rs | 261 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 261 insertions(+) create mode 100644 drivers/block/rnull/configfs.rs (limited to 'drivers/block/rnull/configfs.rs') diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs new file mode 100644 index 000000000..32c10c3f4 --- /dev/null +++ b/drivers/block/rnull/configfs.rs @@ -0,0 +1,261 @@ +// SPDX-License-Identifier: GPL-2.0 + +use super::NullBlkDevice; +use kernel::{ + block::mq::gen_disk::{GenDisk, GenDiskBuilder}, + configfs::{self, AttributeOperations}, + configfs_attrs, + fmt::{self, Write as _}, + new_mutex, + page::PAGE_SIZE, + prelude::*, + str::{kstrtobool_bytes, CString}, + sync::Mutex, +}; + +pub(crate) fn subsystem() -> impl PinInit, Error> { + let item_type = configfs_attrs! { + container: configfs::Subsystem, + data: Config, + child: DeviceConfig, + attributes: [ + features: 0, + ], + }; + + kernel::configfs::Subsystem::new(c"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 { + let mut writer = kernel::str::Formatter::new(page); + writer.write_str("blocksize,size,rotational,irqmode\n")?; + Ok(writer.bytes_written()) + } +} + +#[vtable] +impl configfs::GroupOperations for Config { + type Child = DeviceConfig; + + fn make_group( + &self, + name: &CStr, + ) -> Result, Error>> { + let item_type = configfs_attrs! { + container: configfs::Group, + data: DeviceConfig, + attributes: [ + // Named for compatibility with C null_blk + power: 0, + blocksize: 1, + rotational: 2, + size: 3, + irqmode: 4, + ], + }; + + 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, + irq_mode: IRQMode::None, + name: name.try_into()?, + }), + }), + )) + } +} + +#[derive(Debug, Clone, Copy)] +pub(crate) enum IRQMode { + None, + Soft, +} + +impl TryFrom for IRQMode { + type Error = kernel::error::Error; + + fn try_from(value: u8) -> Result { + match value { + 0 => Ok(Self::None), + 1 => Ok(Self::Soft), + _ => Err(EINVAL), + } + } +} + +impl fmt::Display for IRQMode { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + match self { + Self::None => f.write_str("0")?, + Self::Soft => f.write_str("1")?, + } + Ok(()) + } +} + +#[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, + irq_mode: IRQMode, + disk: Option>, +} + +#[vtable] +impl configfs::AttributeOperations<0> for DeviceConfig { + type Data = DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + 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.irq_mode, + )?); + 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 { + 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::().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 { + 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 { + 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::().map_err(|_| EINVAL)?; + + this.data.lock().capacity_mib = value; + Ok(()) + } +} + +#[vtable] +impl configfs::AttributeOperations<4> for DeviceConfig { + type Data = DeviceConfig; + + fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result { + let mut writer = kernel::str::Formatter::new(page); + writer.write_fmt(fmt!("{}\n", this.data.lock().irq_mode))?; + 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::().map_err(|_| EINVAL)?; + + this.data.lock().irq_mode = IRQMode::try_from(value)?; + Ok(()) + } +} -- cgit v1.3.1