// 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",    description: "Rust implementation of the C null block driver",    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() {}}