Re: [RFC PATCH 10/24] erofs: add device_infos implementation in Rust

Jianan Huang
2024-09-21T09:44:50Z

Yiyang Wu via Linux-erofs <linux-erofs@lists.ozlabs.org> 于2024年9月16日周一 21:57写道：
>
> Add device_infos implementation in rust. It will later be used
> to be put inside the SuperblockInfo. This mask and spec can later
> be used to chunk-based image file block mapping.
>
> Signed-off-by: Yiyang Wu <toolmanp@tlmp.cc>
> ---
> fs/erofs/rust/erofs_sys/devices.rs | 47 ++++++++++++++++++++++++++++++
> 1 file changed, 47 insertions(+)
>
> diff --git a/fs/erofs/rust/erofs_sys/devices.rs b/fs/erofs/rust/erofs_sys/devices.rs
> index 097676ee8720..7495164c7bd0 100644
> --- a/fs/erofs/rust/erofs_sys/devices.rs
> +++ b/fs/erofs/rust/erofs_sys/devices.rs
> @@ -1,6 +1,10 @@
> // Copyright 2024 Yiyang Wu
> // SPDX-License-Identifier: MIT or GPL-2.0-or-later
>
> +use super::alloc_helper::*;
> +use super::data::raw_iters::*;
> +use super::data::*;
> +use super::*;
> use alloc::vec::Vec;
>
> /// Device specification.
> @@ -21,8 +25,51 @@ pub(crate) struct DeviceSlot {
> reserved: [u8; 56],
> }
>
> +impl From<[u8; 128]> for DeviceSlot {
> + fn from(data: [u8; 128]) -> Self {
> + Self {
> + tags: data[0..64].try_into().unwrap(),
> + blocks: u32::from_le_bytes([data[64], data[65], data[66], data[67]]),
> + mapped_blocks: u32::from_le_bytes([data[68], data[69], data[70], data[71]]),
> + reserved: data[72..128].try_into().unwrap(),
> + }
> + }
> +}
> +
> /// Device information.
> pub(crate) struct DeviceInfo {
> pub(crate) mask: u16,
> pub(crate) specs: Vec<DeviceSpec>,
> }
> +
> +pub(crate) fn get_device_infos<'a>(
> + iter: &mut (dyn ContinuousBufferIter<'a> + 'a),
> +) -> PosixResult<DeviceInfo> {
> + let mut specs = Vec::new();
> + for data in iter {
> + let buffer = data?;
> + let mut cur: usize = 0;
> + let len = buffer.content().len();
> + while cur + 128 <= len {

It is better to use macros instead of hardcode, like:
const EROFS_DEVT_SLOT_SIZE: usize = size_of::<DeviceSlot>();
Also works to the other similar usages in this patch set.

Thanks,
Jianan

>
> + let slot_data: [u8; 128] = buffer.content()[cur..cur + 128].try_into().unwrap();
> + let slot = DeviceSlot::from(slot_data);
> + cur += 128;
> + push_vec(
> + &mut specs,
> + DeviceSpec {
> + tags: slot.tags,
> + blocks: slot.blocks,
> + mapped_blocks: slot.mapped_blocks,
> + },
> + )?;
> + }
> + }
> +
> + let mask = if specs.is_empty() {
> + 0
> + } else {
> + (1 << (specs.len().ilog2() + 1)) - 1
> + };
> +
> + Ok(DeviceInfo { mask, specs })
> +}
> --
> 2.46.0
>