[RFC PATCH 08/24] erofs: add device data structure in Rust

[Jianan Huang]

Yiyang Wu via Linux-erofs <linux-erofs at lists.ozlabs.org> 于2024年9月16日周一
21:57写道：

> This patch introduce device data structure in Rust.
> It can later support chunk based block maps.
>
> Signed-off-by: Yiyang Wu <toolmanp at tlmp.cc>
> ---
>  fs/erofs/rust/erofs_sys.rs         |  1 +
>  fs/erofs/rust/erofs_sys/devices.rs | 28 ++++++++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
>  create mode 100644 fs/erofs/rust/erofs_sys/devices.rs
>
> diff --git a/fs/erofs/rust/erofs_sys.rs b/fs/erofs/rust/erofs_sys.rs
> index 8cca2cd9b75f..f1a1e491caec 100644
> --- a/fs/erofs/rust/erofs_sys.rs
> +++ b/fs/erofs/rust/erofs_sys.rs
> @@ -25,6 +25,7 @@
>
>  pub(crate) mod alloc_helper;
>  pub(crate) mod data;
> +pub(crate) mod devices;
>  pub(crate) mod errnos;
>  pub(crate) mod inode;
>  pub(crate) mod superblock;
> diff --git a/fs/erofs/rust/erofs_sys/devices.rs b/fs/erofs/rust/erofs_sys/
> devices.rs
> new file mode 100644
> index 000000000000..097676ee8720
> --- /dev/null
> +++ b/fs/erofs/rust/erofs_sys/devices.rs
> @@ -0,0 +1,28 @@
> +// Copyright 2024 Yiyang Wu
> +// SPDX-License-Identifier: MIT or GPL-2.0-or-later
> +
> +use alloc::vec::Vec;
> +
> +/// Device specification.
> +#[derive(Copy, Clone, Debug)]
> +pub(crate) struct DeviceSpec {
> +    pub(crate) tags: [u8; 64],
>

I think we don't need to keep tags in the memory. It's not used in flatdev
mode
or when mount with "-o device". It can be replaced with a string like the C
version,
since it may represent a file path of variable length, or ignore this field
for now.

Thanks,
Jianan


> +    pub(crate) blocks: u32,
> +    pub(crate) mapped_blocks: u32,
> +}
> +
> +/// Device slot.
> +#[derive(Copy, Clone, Debug)]
> +#[repr(C)]
> +pub(crate) struct DeviceSlot {
> +    tags: [u8; 64],
> +    blocks: u32,
> +    mapped_blocks: u32,
> +    reserved: [u8; 56],
> +}
> +
> +/// Device information.
> +pub(crate) struct DeviceInfo {
> +    pub(crate) mask: u16,
> +    pub(crate) specs: Vec<DeviceSpec>,
> +}
> --
> 2.46.0
>
>
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