[RFC,02/24] erofs: add superblock data structure in Rust

Message ID	20240916135634.98554-3-toolmanp@tlmp.cc (mailing list archive)
State	New
Headers	show Received: from mail.tlmp.cc (unknown [148.135.17.20]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 69BD5157E61; Mon, 16 Sep 2024 13:56:43 +0000 (UTC) From: Yiyang Wu <toolmanp@tlmp.cc> To: linux-erofs@lists.ozlabs.org Cc: rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org> Subject: [RFC PATCH 02/24] erofs: add superblock data structure in Rust Date: Mon, 16 Sep 2024 21:56:12 +0800 Message-ID: <20240916135634.98554-3-toolmanp@tlmp.cc> In-Reply-To: <20240916135634.98554-1-toolmanp@tlmp.cc> References: <20240916135634.98554-1-toolmanp@tlmp.cc> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	erofs: introduce Rust implementation \| expand [RFC,00/24] erofs: introduce Rust implementation [RFC,01/24] erofs: lift up erofs_fill_inode to global [RFC,02/24] erofs: add superblock data structure in Rust [RFC,03/24] erofs: add Errno in Rust [RFC,04/24] erofs: add xattrs data structure in Rust [RFC,05/24] erofs: add inode data structure in Rust [RFC,06/24] erofs: add alloc_helper in Rust [RFC,07/24] erofs: add data abstraction in Rust [RFC,08/24] erofs: add device data structure in Rust [RFC,09/24] erofs: add continuous iterators in Rust [RFC,10/24] erofs: add device_infos implementation in Rust [RFC,11/24] erofs: add map data structure in Rust [RFC,12/24] erofs: add directory entry data structure in Rust [RFC,13/24] erofs: add runtime filesystem and inode in Rust [RFC,14/24] erofs: add block mapping capability in Rust [RFC,15/24] erofs: add iter methods in filesystem in Rust [RFC,16/24] erofs: implement dir and inode operations in Rust [RFC,17/24] erofs: introduce Rust SBI to C [RFC,18/24] erofs: introduce iget alternative to C [RFC,19/24] erofs: introduce namei alternative to C [RFC,20/24] erofs: introduce readdir alternative to C [RFC,21/24] erofs: introduce erofs_map_blocks alternative to C [RFC,22/24] erofs: add skippable iters in Rust [RFC,23/24] erofs: implement xattrs operations in Rust [RFC,24/24] erofs: introduce xattrs replacement to C

diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig index 6ea60661fa55..e2883efbf497 100644 --- a/fs/erofs/Kconfig +++ b/fs/erofs/Kconfig @@ -178,3 +178,13 @@ config EROFS_FS_PCPU_KTHREAD_HIPRI at higher priority. If unsure, say N. + +config EROFS_FS_RUST + bool "EROFS use RUST Replacement (EXPERIMENTAL)" + depends on EROFS_FS && RUST + help + This permits EROFS to use EXPERIMENTAL Rust implementation + for EROFS. This should be considered as an experimental + feature for now. + + If unsure, say N. diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile index 4331d53c7109..fb46a2c7fb50 100644 --- a/fs/erofs/Makefile +++ b/fs/erofs/Makefile @@ -9,3 +9,4 @@ erofs-$(CONFIG_EROFS_FS_ZIP_DEFLATE) += decompressor_deflate.o erofs-$(CONFIG_EROFS_FS_ZIP_ZSTD) += decompressor_zstd.o erofs-$(CONFIG_EROFS_FS_BACKED_BY_FILE) += fileio.o erofs-$(CONFIG_EROFS_FS_ONDEMAND) += fscache.o +erofs-$(CONFIG_EROFS_FS_RUST) += super_rs.o diff --git a/fs/erofs/rust/erofs_sys.rs b/fs/erofs/rust/erofs_sys.rs new file mode 100644 index 000000000000..0f1400175fc2 --- /dev/null +++ b/fs/erofs/rust/erofs_sys.rs @@ -0,0 +1,22 @@ +#![allow(dead_code)] +// Copyright 2024 Yiyang Wu +// SPDX-License-Identifier: MIT or GPL-2.0-or-later + +//! A pure Rust implementation of the EROFS filesystem. +//! Technical Details are documented in the [EROFS Documentation](https://erofs.docs.kernel.org/en/latest/) + +// It's unavoidable to import alloc here. Since there are so many backends there and if we want to +// to use trait object to export Filesystem pointer. The alloc crate here is necessary. + +#[cfg(not(CONFIG_EROFS_FS = "y"))] +extern crate alloc; + +/// Erofs requires block index to a 32 bit unsigned integer. +pub(crate) type Blk = u32; +/// Erofs requires normal offset to be a 64bit unsigned integer. +pub(crate) type Off = u64; +/// Erofs requires inode nid to be a 64bit unsigned integer. +pub(crate) type Nid = u64; +/// Erofs Super Offset to read the ondisk superblock +pub(crate) const EROFS_SUPER_OFFSET: Off = 1024; +pub(crate) mod superblock; diff --git a/fs/erofs/rust/erofs_sys/superblock.rs b/fs/erofs/rust/erofs_sys/superblock.rs new file mode 100644 index 000000000000..213be6dbc553 --- /dev/null +++ b/fs/erofs/rust/erofs_sys/superblock.rs @@ -0,0 +1,132 @@ +// Copyright 2024 Yiyang Wu +// SPDX-License-Identifier: MIT or GPL-2.0-or-later + +use super::*; +use core::mem::size_of; + +/// The ondisk superblock structure. +#[derive(Debug, Clone, Copy, Default)] +#[repr(C)] +pub(crate) struct SuperBlock { + pub(crate) magic: u32, + pub(crate) checksum: i32, + pub(crate) feature_compat: i32, + pub(crate) blkszbits: u8, + pub(crate) sb_extslots: u8, + pub(crate) root_nid: i16, + pub(crate) inos: i64, + pub(crate) build_time: i64, + pub(crate) build_time_nsec: i32, + pub(crate) blocks: i32, + pub(crate) meta_blkaddr: u32, + pub(crate) xattr_blkaddr: u32, + pub(crate) uuid: [u8; 16], + pub(crate) volume_name: [u8; 16], + pub(crate) feature_incompat: i32, + pub(crate) compression: i16, + pub(crate) extra_devices: i16, + pub(crate) devt_slotoff: i16, + pub(crate) dirblkbits: u8, + pub(crate) xattr_prefix_count: u8, + pub(crate) xattr_prefix_start: i32, + pub(crate) packed_nid: i64, + pub(crate) xattr_filter_reserved: u8, + pub(crate) reserved: [u8; 23], +} + +impl TryFrom<&[u8]> for SuperBlock { + type Error = core::array::TryFromSliceError; + fn try_from(value: &[u8]) -> Result<Self, Self::Error> { + value[0..128].try_into() + } +} + +impl From<[u8; 128]> for SuperBlock { + fn from(value: [u8; 128]) -> Self { + Self { + magic: u32::from_le_bytes([value[0], value[1], value[2], value[3]]), + checksum: i32::from_le_bytes([value[4], value[5], value[6], value[7]]), + feature_compat: i32::from_le_bytes([value[8], value[9], value[10], value[11]]), + blkszbits: value[12], + sb_extslots: value[13], + root_nid: i16::from_le_bytes([value[14], value[15]]), + inos: i64::from_le_bytes([ + value[16], value[17], value[18], value[19], value[20], value[21], value[22], + value[23], + ]), + build_time: i64::from_le_bytes([ + value[24], value[25], value[26], value[27], value[28], value[29], value[30], + value[31], + ]), + build_time_nsec: i32::from_le_bytes([value[32], value[33], value[34], value[35]]), + blocks: i32::from_le_bytes([value[36], value[37], value[38], value[39]]), + meta_blkaddr: u32::from_le_bytes([value[40], value[41], value[42], value[43]]), + xattr_blkaddr: u32::from_le_bytes([value[44], value[45], value[46], value[47]]), + uuid: value[48..64].try_into().unwrap(), + volume_name: value[64..80].try_into().unwrap(), + feature_incompat: i32::from_le_bytes([value[80], value[81], value[82], value[83]]), + compression: i16::from_le_bytes([value[84], value[85]]), + extra_devices: i16::from_le_bytes([value[86], value[87]]), + devt_slotoff: i16::from_le_bytes([value[88], value[89]]), + dirblkbits: value[90], + xattr_prefix_count: value[91], + xattr_prefix_start: i32::from_le_bytes([value[92], value[93], value[94], value[95]]), + packed_nid: i64::from_le_bytes([ + value[96], value[97], value[98], value[99], value[100], value[101], value[102], + value[103], + ]), + xattr_filter_reserved: value[104], + reserved: value[105..128].try_into().unwrap(), + } + } +} + +pub(crate) type SuperBlockBuf = [u8; size_of::<SuperBlock>()]; +pub(crate) const SUPERBLOCK_EMPTY_BUF: SuperBlockBuf = [0; size_of::<SuperBlock>()]; + +/// Used for external address calculation. +pub(crate) struct Accessor { + pub(crate) base: Off, + pub(crate) off: Off, + pub(crate) len: Off, + pub(crate) nr: Off, +} + +impl Accessor { + pub(crate) fn new(address: Off, bits: Off) -> Self { + let sz = 1 << bits; + let mask = sz - 1; + Accessor { + base: (address >> bits) << bits, + off: address & mask, + len: sz - (address & mask), + nr: address >> bits, + } + } +} + +impl SuperBlock { + pub(crate) fn blk_access(&self, address: Off) -> Accessor { + Accessor::new(address, self.blkszbits as Off) + } + + pub(crate) fn blknr(&self, pos: Off) -> Blk { + (pos >> self.blkszbits) as Blk + } + + pub(crate) fn blkpos(&self, blk: Blk) -> Off { + (blk as Off) << self.blkszbits + } + + pub(crate) fn blksz(&self) -> Off { + 1 << self.blkszbits + } + + pub(crate) fn blk_round_up(&self, addr: Off) -> Blk { + ((addr + self.blksz() - 1) >> self.blkszbits) as Blk + } + + pub(crate) fn iloc(&self, nid: Nid) -> Off { + self.blkpos(self.meta_blkaddr) + ((nid as Off) << (5 as Off)) + } +} diff --git a/fs/erofs/rust/mod.rs b/fs/erofs/rust/mod.rs new file mode 100644 index 000000000000..e6c0731f2533 --- /dev/null +++ b/fs/erofs/rust/mod.rs @@ -0,0 +1,4 @@ +// Copyright 2024 Yiyang Wu +// SPDX-License-Identifier: MIT or GPL-2.0-or-later + +pub(crate) mod erofs_sys; diff --git a/fs/erofs/super_rs.rs b/fs/erofs/super_rs.rs new file mode 100644 index 000000000000..4b8cbef507e3 --- /dev/null +++ b/fs/erofs/super_rs.rs @@ -0,0 +1,9 @@ +// Copyright 2024 Yiyang Wu +// SPDX-License-Identifier: MIT or GPL-2.0-or-later + +//! EROFS Rust Kernel Module Helpers Implementation +//! This is only for experimental purpose. Feedback is always welcome. + +#[allow(dead_code)] +#[allow(missing_docs)] +pub(crate) mod rust;

[RFC,02/24] erofs: add superblock data structure in Rust

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