| 1 | // SPDX-License-Identifier: GPL-2.0 |
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| 2 | |
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| 3 | //! This is a Rust implementation of the C null block driver. |
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| 4 | //! |
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| 5 | //! Supported features: |
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| 6 | //! |
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| 7 | //! - blk-mq interface |
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| 8 | //! - direct completion |
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| 9 | //! - block size 4k |
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| 10 | //! |
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| 11 | //! The driver is not configurable. |
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| 12 | |
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| 13 | use kernel::{ |
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| 14 | alloc::flags, |
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| 15 | block::mq::{ |
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| 16 | self, |
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| 17 | gen_disk::{self, GenDisk}, |
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| 18 | Operations, TagSet, |
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| 19 | }, |
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| 20 | error::Result, |
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| 21 | new_mutex, pr_info, |
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| 22 | prelude::*, |
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| 23 | sync::{Arc, Mutex}, |
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| 24 | types::ARef, |
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| 25 | }; |
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| 26 | |
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| 27 | module! { |
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| 28 | type: NullBlkModule, |
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| 29 | name: "rnull_mod" , |
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| 30 | authors: ["Andreas Hindborg" ], |
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| 31 | description: "Rust implementation of the C null block driver" , |
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| 32 | license: "GPL v2" , |
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| 33 | } |
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| 34 | |
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| 35 | #[pin_data] |
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| 36 | struct NullBlkModule { |
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| 37 | #[pin] |
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| 38 | _disk: Mutex<GenDisk<NullBlkDevice>>, |
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| 39 | } |
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| 40 | |
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| 41 | impl kernel::InPlaceModule for NullBlkModule { |
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| 42 | fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> { |
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| 43 | pr_info!("Rust null_blk loaded\n" ); |
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| 44 | |
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| 45 | // Use a immediately-called closure as a stable `try` block |
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| 46 | let disk = /* try */ (|| { |
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| 47 | let tagset = Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?; |
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| 48 | |
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| 49 | gen_disk::GenDiskBuilder::new() |
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| 50 | .capacity_sectors(4096 << 11) |
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| 51 | .logical_block_size(4096)? |
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| 52 | .physical_block_size(4096)? |
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| 53 | .rotational(false) |
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| 54 | .build(format_args!("rnullb{}" , 0), tagset) |
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| 55 | })(); |
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| 56 | |
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| 57 | try_pin_init!(Self { |
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| 58 | _disk <- new_mutex!(disk?, "nullb:disk" ), |
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| 59 | }) |
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| 60 | } |
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| 61 | } |
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| 62 | |
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| 63 | struct NullBlkDevice; |
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| 64 | |
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| 65 | #[vtable] |
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| 66 | impl Operations for NullBlkDevice { |
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| 67 | #[inline(always)] |
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| 68 | fn queue_rq(rq: ARef<mq::Request<Self>>, _is_last: bool) -> Result { |
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| 69 | mq::Request::end_ok(rq) |
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| 70 | .map_err(|_e| kernel::error::code::EIO) |
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| 71 | // We take no refcounts on the request, so we expect to be able to |
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| 72 | // end the request. The request reference must be unique at this |
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| 73 | // point, and so `end_ok` cannot fail. |
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| 74 | .expect("Fatal error - expected to be able to end request" ); |
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| 75 | |
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| 76 | Ok(()) |
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| 77 | } |
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| 78 | |
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| 79 | fn commit_rqs() {} |
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| 80 | } |
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| 81 | |
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