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// 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.
use kernel::{
alloc::flags,
block::mq::{
self,
gen_disk::{self, GenDisk},
Operations, TagSet,
},
error::Result,
new_mutex, pr_info,
prelude::*,
sync::{Arc, Mutex},
types::ARef,
};
module! {
type: NullBlkModule,
name: "rnull_mod",
author: "Andreas Hindborg",
license: "GPL v2",
}
struct NullBlkModule {
_disk: Pin<KBox<Mutex<GenDisk<NullBlkDevice>>>>,
}
impl kernel::Module for NullBlkModule {
fn init(_module: &'static ThisModule) -> Result<Self> {
pr_info!("Rust null_blk loaded\n");
let tagset = Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?;
let disk = gen_disk::GenDiskBuilder::new()
.capacity_sectors(4096 << 11)
.logical_block_size(4096)?
.physical_block_size(4096)?
.rotational(false)
.build(format_args!("rnullb{}", 0), tagset)?;
let disk = KBox::pin_init(new_mutex!(disk, "nullb:disk"), flags::GFP_KERNEL)?;
Ok(Self { _disk: disk })
}
}
struct NullBlkDevice;
#[vtable]
impl Operations for NullBlkDevice {
#[inline(always)]
fn queue_rq(rq: ARef<mq::Request<Self>>, _is_last: bool) -> Result {
mq::Request::end_ok(rq)
.map_err(|_e| kernel::error::code::EIO)
// We take no refcounts on the request, so we expect to be able to
// end the request. The request reference must be unique at this
// point, and so `end_ok` cannot fail.
.expect("Fatal error - expected to be able to end request");
Ok(())
}
fn commit_rqs() {}
}
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