1 // SPDX-License-Identifier: GPL-2.0
2
3 //! This module provides types for implementin
4 //! blk-mq subsystem.
5 //!
6 //! To implement a block device driver, a Rust
7 //!
8 //! - Implement [`Operations`] for a type `T`.
9 //! - Create a [`TagSet<T>`].
10 //! - Create a [`GenDisk<T>`], via the [`GenDi
11 //! - Add the disk to the system by calling [`
12 //! the `TagSet` reference.
13 //!
14 //! The types available in this module that ha
15 //!
16 //! - The [`TagSet`] type that abstracts the C
17 //! - The [`GenDisk`] type that abstracts the
18 //! - The [`Request`] type that abstracts the
19 //!
20 //! The kernel will interface with the block d
21 //! implementations of the `Operations` trait.
22 //!
23 //! IO requests are passed to the driver as [`
24 //! instances. The `Request` type is a wrapper
25 //! The driver must mark end of processing by
26 //! `Request::end`, methods. Failure to do so
27 //! errors. Please note that the C function `b
28 //! called when the request is queued with the
29 //!
30 //! The `TagSet` is responsible for creating a
31 //! `Request`s and integer ids as well as carr
32 //! generated by `Operations`. This mapping is
33 //! completions from hardware with the correct
34 //! determines the maximum queue depth by sett
35 //! instances available to the driver, and it
36 //! instantiate for the driver. If possible, a
37 //! per core, to keep queue data local to a co
38 //!
39 //! One `TagSet` instance can be shared betwee
40 //! This can be useful when implementing drive
41 //! with one set of IO resources are represent
42 //!
43 //! One significant difference between block d
44 //! these Rust abstractions and drivers implem
45 //! drivers have to own a reference count on t
46 //! in flight. This is to ensure that the C `s
47 //! the Rust `Request` instances are live whil
48 //! reference to the `Request`. In addition, t
49 //! a `Request` via the `TagSet` would not be
50 //!
51 //! [`GenDisk`]: gen_disk::GenDisk
52 //! [`GenDisk<T>`]: gen_disk::GenDisk
53 //! [`GenDiskBuilder`]: gen_disk::GenDiskBuild
54 //! [`GenDiskBuilder::build`]: gen_disk::GenDi
55 //!
56 //! # Example
57 //!
58 //! ```rust
59 //! use kernel::{
60 //! alloc::flags,
61 //! block::mq::*,
62 //! new_mutex,
63 //! prelude::*,
64 //! sync::{Arc, Mutex},
65 //! types::{ARef, ForeignOwnable},
66 //! };
67 //!
68 //! struct MyBlkDevice;
69 //!
70 //! #[vtable]
71 //! impl Operations for MyBlkDevice {
72 //!
73 //! fn queue_rq(rq: ARef<Request<Self>>, _
74 //! Request::end_ok(rq);
75 //! Ok(())
76 //! }
77 //!
78 //! fn commit_rqs() {}
79 //! }
80 //!
81 //! let tagset: Arc<TagSet<MyBlkDevice>> =
82 //! Arc::pin_init(TagSet::new(1, 256, 1),
83 //! let mut disk = gen_disk::GenDiskBuilder::n
84 //! .capacity_sectors(4096)
85 //! .build(format_args!("myblk"), tagset)?
86 //!
87 //! # Ok::<(), kernel::error::Error>(())
88 //! ```
89
90 pub mod gen_disk;
91 mod operations;
92 mod raw_writer;
93 mod request;
94 mod tag_set;
95
96 pub use operations::Operations;
97 pub use request::Request;
98 pub use tag_set::TagSet;
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