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Message-Id: <20240514131711.379322-30-wedsonaf@gmail.com>
Date: Tue, 14 May 2024 10:17:10 -0300
From: Wedson Almeida Filho <wedsonaf@...il.com>
To: Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>,
Matthew Wilcox <willy@...radead.org>,
Dave Chinner <david@...morbit.com>
Cc: Kent Overstreet <kent.overstreet@...il.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-fsdevel@...r.kernel.org,
rust-for-linux@...r.kernel.org,
linux-kernel@...r.kernel.org,
Wedson Almeida Filho <walmeida@...rosoft.com>
Subject: [RFC PATCH v2 29/30] tarfs: introduce tar fs
From: Wedson Almeida Filho <walmeida@...rosoft.com>
It is a file system based on tar files and an index appended to them (to
facilitate finding fs entries without having to traverse the whole tar
file).
Signed-off-by: Wedson Almeida Filho <walmeida@...rosoft.com>
---
fs/Kconfig | 1 +
fs/Makefile | 1 +
fs/tarfs/Kconfig | 15 ++
fs/tarfs/Makefile | 8 +
fs/tarfs/defs.rs | 80 ++++++
fs/tarfs/tar.rs | 394 ++++++++++++++++++++++++++++++
scripts/generate_rust_analyzer.py | 2 +-
7 files changed, 500 insertions(+), 1 deletion(-)
create mode 100644 fs/tarfs/Kconfig
create mode 100644 fs/tarfs/Makefile
create mode 100644 fs/tarfs/defs.rs
create mode 100644 fs/tarfs/tar.rs
diff --git a/fs/Kconfig b/fs/Kconfig
index a46b0cbc4d8f..2cbd99d6784c 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -337,6 +337,7 @@ source "fs/sysv/Kconfig"
source "fs/ufs/Kconfig"
source "fs/erofs/Kconfig"
source "fs/vboxsf/Kconfig"
+source "fs/tarfs/Kconfig"
endif # MISC_FILESYSTEMS
diff --git a/fs/Makefile b/fs/Makefile
index 6ecc9b0a53f2..d8bbda73e3a9 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -129,3 +129,4 @@ obj-$(CONFIG_EFIVAR_FS) += efivarfs/
obj-$(CONFIG_EROFS_FS) += erofs/
obj-$(CONFIG_VBOXSF_FS) += vboxsf/
obj-$(CONFIG_ZONEFS_FS) += zonefs/
+obj-$(CONFIG_TARFS_FS) += tarfs/
diff --git a/fs/tarfs/Kconfig b/fs/tarfs/Kconfig
new file mode 100644
index 000000000000..fd4f1ae0f83d
--- /dev/null
+++ b/fs/tarfs/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+config TARFS_FS
+ tristate "TAR file system support"
+ depends on RUST && BLOCK
+ help
+ This is a simple read-only file system intended for mounting
+ tar files that have had an index appened to them.
+
+ To compile this file system support as a module, choose M here: the
+ module will be called tarfs.
+
+ If you don't know whether you need it, then you don't need it:
+ answer N.
diff --git a/fs/tarfs/Makefile b/fs/tarfs/Makefile
new file mode 100644
index 000000000000..011c5d64fbe3
--- /dev/null
+++ b/fs/tarfs/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the linux tarfs filesystem routines.
+#
+
+obj-$(CONFIG_TARFS_FS) += tarfs.o
+
+tarfs-y := tar.o
diff --git a/fs/tarfs/defs.rs b/fs/tarfs/defs.rs
new file mode 100644
index 000000000000..7481b75aaab2
--- /dev/null
+++ b/fs/tarfs/defs.rs
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Definitions of tarfs structures.
+
+use kernel::types::LE;
+
+/// Flags used in [`Inode::flags`].
+pub mod inode_flags {
+ /// Indicates that the inode is opaque.
+ ///
+ /// When set, inode will have the "trusted.overlay.opaque" set to "y" at runtime.
+ pub const OPAQUE: u8 = 0x1;
+}
+
+kernel::derive_readable_from_bytes! {
+ /// An inode in the tarfs inode table.
+ #[repr(C)]
+ pub struct Inode {
+ /// The mode of the inode.
+ ///
+ /// The bottom 9 bits are the rwx bits for owner, group, all.
+ ///
+ /// The bits in the [`S_IFMT`] mask represent the file mode.
+ pub mode: LE<u16>,
+
+ /// Tarfs flags for the inode.
+ ///
+ /// Values are drawn from the [`inode_flags`] module.
+ pub flags: u8,
+
+ /// The bottom 4 bits represent the top 4 bits of mtime.
+ pub hmtime: u8,
+
+ /// The owner of the inode.
+ pub owner: LE<u32>,
+
+ /// The group of the inode.
+ pub group: LE<u32>,
+
+ /// The bottom 32 bits of mtime.
+ pub lmtime: LE<u32>,
+
+ /// Size of the contents of the inode.
+ pub size: LE<u64>,
+
+ /// Either the offset to the data, or the major and minor numbers of a device.
+ ///
+ /// For the latter, the 32 LSB are the minor, and the 32 MSB are the major numbers.
+ pub offset: LE<u64>,
+ }
+
+ /// An entry in a tarfs directory entry table.
+ #[repr(C)]
+ pub struct DirEntry {
+ /// The inode number this entry refers to.
+ pub ino: LE<u64>,
+
+ /// The offset to the name of the entry.
+ pub name_offset: LE<u64>,
+
+ /// The length of the name of the entry.
+ pub name_len: LE<u64>,
+
+ /// The type of entry.
+ pub etype: u8,
+
+ /// Unused padding.
+ pub _padding: [u8; 7],
+ }
+
+ /// The super-block of a tarfs instance.
+ #[repr(C)]
+ pub struct Header {
+ /// The offset to the beginning of the inode-table.
+ pub inode_table_offset: LE<u64>,
+
+ /// The number of inodes in the file system.
+ pub inode_count: LE<u64>,
+ }
+}
diff --git a/fs/tarfs/tar.rs b/fs/tarfs/tar.rs
new file mode 100644
index 000000000000..a3f6e468e566
--- /dev/null
+++ b/fs/tarfs/tar.rs
@@ -0,0 +1,394 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! File system based on tar files and an index.
+
+use core::mem::size_of;
+use defs::*;
+use kernel::fs::{
+ self, address_space, dentry, dentry::DEntry, file, file::File, inode, inode::INode,
+ inode::Type, iomap, sb, sb::SuperBlock, Offset, Stat,
+};
+use kernel::types::{ARef, Either, FromBytes, Locked};
+use kernel::{c_str, prelude::*, str::CString, user};
+
+pub mod defs;
+
+kernel::module_fs! {
+ type: TarFs,
+ name: "tarfs",
+ author: "Wedson Almeida Filho <walmeida@...rosoft.com>",
+ description: "File system for indexed tar files",
+ license: "GPL",
+}
+
+const SECTOR_SIZE: u64 = 512;
+const TARFS_BSIZE: u64 = 1 << TARFS_BSIZE_BITS;
+const TARFS_BSIZE_BITS: u8 = 12;
+const SECTORS_PER_BLOCK: u64 = TARFS_BSIZE / SECTOR_SIZE;
+const TARFS_MAGIC: usize = 0x54415246;
+
+static_assert!(SECTORS_PER_BLOCK > 0);
+
+struct INodeData {
+ offset: u64,
+ flags: u8,
+}
+
+struct TarFs {
+ data_size: u64,
+ inode_table_offset: u64,
+ inode_count: u64,
+ mapper: inode::Mapper,
+}
+
+impl TarFs {
+ fn iget(sb: &SuperBlock<Self>, ino: u64) -> Result<ARef<INode<Self>>> {
+ // Check that the inode number is valid.
+ let h = sb.data();
+ if ino == 0 || ino > h.inode_count {
+ return Err(ENOENT);
+ }
+
+ // Create an inode or find an existing (cached) one.
+ let mut inode = match sb.get_or_create_inode(ino)? {
+ Either::Left(existing) => return Ok(existing),
+ Either::Right(new) => new,
+ };
+
+ static_assert!((TARFS_BSIZE as usize) % size_of::<Inode>() == 0);
+
+ // Load inode details from storage.
+ let offset = h.inode_table_offset + (ino - 1) * u64::try_from(size_of::<Inode>())?;
+ let b = h.mapper.mapped_folio(offset.try_into()?)?;
+ let idata = Inode::from_bytes(&b, 0).ok_or(EIO)?;
+
+ let mode = idata.mode.value();
+
+ // Ignore inodes that have unknown mode bits.
+ if (mode & !(fs::mode::S_IFMT | 0o777)) != 0 {
+ return Err(ENOENT);
+ }
+
+ const DIR_FOPS: file::Ops<TarFs> = file::Ops::new::<TarFs>();
+ const DIR_IOPS: inode::Ops<TarFs> = inode::Ops::new::<TarFs>();
+ const FILE_AOPS: address_space::Ops<TarFs> = iomap::ro_aops::<TarFs>();
+
+ let size = idata.size.value();
+ let doffset = idata.offset.value();
+ let secs = u64::from(idata.lmtime.value()) | (u64::from(idata.hmtime & 0xf) << 32);
+ let ts = kernel::time::Timespec::new(secs, 0)?;
+ let typ = match mode & fs::mode::S_IFMT {
+ fs::mode::S_IFREG => {
+ inode
+ .set_fops(file::Ops::generic_ro_file())
+ .set_aops(FILE_AOPS);
+ Type::Reg
+ }
+ fs::mode::S_IFDIR => {
+ inode.set_iops(DIR_IOPS).set_fops(DIR_FOPS);
+ Type::Dir
+ }
+ fs::mode::S_IFLNK => {
+ inode.set_iops(inode::Ops::simple_symlink_inode());
+ Type::Lnk(Some(Self::get_link(sb, doffset, size)?))
+ }
+ fs::mode::S_IFSOCK => Type::Sock,
+ fs::mode::S_IFIFO => Type::Fifo,
+ fs::mode::S_IFCHR => Type::Chr((doffset >> 32) as u32, doffset as u32),
+ fs::mode::S_IFBLK => Type::Blk((doffset >> 32) as u32, doffset as u32),
+ _ => return Err(ENOENT),
+ };
+ inode.init(inode::Params {
+ typ,
+ mode: mode & 0o777,
+ size: size.try_into()?,
+ blocks: (idata.size.value() + TARFS_BSIZE - 1) / TARFS_BSIZE,
+ nlink: 1,
+ uid: idata.owner.value(),
+ gid: idata.group.value(),
+ ctime: ts,
+ mtime: ts,
+ atime: ts,
+ value: INodeData {
+ offset: doffset,
+ flags: idata.flags,
+ },
+ })
+ }
+
+ fn name_eq(sb: &SuperBlock<Self>, mut name: &[u8], offset: u64) -> Result<bool> {
+ let ret =
+ sb.data()
+ .mapper
+ .for_each_page(offset as Offset, name.len().try_into()?, |data| {
+ if data != &name[..data.len()] {
+ return Ok(Some(()));
+ }
+ name = &name[data.len()..];
+ Ok(None)
+ })?;
+ Ok(ret.is_none())
+ }
+
+ fn read_name(sb: &SuperBlock<Self>, name: &mut [u8], offset: u64) -> Result {
+ let mut copy_to = 0;
+ sb.data()
+ .mapper
+ .for_each_page(offset as Offset, name.len().try_into()?, |data| {
+ name[copy_to..][..data.len()].copy_from_slice(data);
+ copy_to += data.len();
+ Ok(None::<()>)
+ })?;
+ Ok(())
+ }
+
+ fn get_link(sb: &SuperBlock<Self>, offset: u64, len: u64) -> Result<CString> {
+ let name_len: usize = len.try_into()?;
+ let alloc_len = name_len.checked_add(1).ok_or(ENOMEM)?;
+ let mut name = Box::new_slice(alloc_len, b'\0', GFP_NOFS)?;
+ Self::read_name(sb, &mut name[..name_len], offset)?;
+ Ok(name.try_into()?)
+ }
+}
+
+impl fs::FileSystem for TarFs {
+ type Data = Box<Self>;
+ type INodeData = INodeData;
+ const NAME: &'static CStr = c_str!("tar");
+ const SUPER_TYPE: sb::Type = sb::Type::BlockDev;
+
+ fn fill_super(
+ sb: &mut SuperBlock<Self, sb::New>,
+ mapper: Option<inode::Mapper>,
+ ) -> Result<Self::Data> {
+ let Some(mapper) = mapper else {
+ return Err(EINVAL);
+ };
+
+ let scount = sb.sector_count();
+ if scount < SECTORS_PER_BLOCK {
+ pr_err!("Block device is too small: sector count={scount}\n");
+ return Err(ENXIO);
+ }
+
+ if sb.min_blocksize(SECTOR_SIZE as i32) != SECTOR_SIZE as i32 {
+ pr_err!("Block size not supported\n");
+ return Err(EIO);
+ }
+
+ let tarfs = {
+ let offset = (scount - 1) * SECTOR_SIZE;
+ let mapped = mapper.mapped_folio(offset.try_into()?)?;
+ let hdr = Header::from_bytes(&mapped, 0).ok_or(EIO)?;
+ let inode_table_offset = hdr.inode_table_offset.value();
+ let inode_count = hdr.inode_count.value();
+ drop(mapped);
+ Box::new(
+ TarFs {
+ inode_table_offset,
+ inode_count,
+ data_size: scount.checked_mul(SECTOR_SIZE).ok_or(ERANGE)?,
+ mapper,
+ },
+ GFP_KERNEL,
+ )?
+ };
+
+ // Check that the inode table starts within the device data and is aligned to the block
+ // size.
+ if tarfs.inode_table_offset >= tarfs.data_size {
+ pr_err!(
+ "inode table offset beyond data size: {} >= {}\n",
+ tarfs.inode_table_offset,
+ tarfs.data_size
+ );
+ return Err(E2BIG);
+ }
+
+ if tarfs.inode_table_offset % SECTOR_SIZE != 0 {
+ pr_err!(
+ "inode table offset not aligned to sector size: {}\n",
+ tarfs.inode_table_offset,
+ );
+ return Err(EDOM);
+ }
+
+ // Check that the last inode is within bounds (and that there is no overflow when
+ // calculating its offset).
+ let offset = tarfs
+ .inode_count
+ .checked_mul(u64::try_from(size_of::<Inode>())?)
+ .ok_or(ERANGE)?
+ .checked_add(tarfs.inode_table_offset)
+ .ok_or(ERANGE)?;
+ if offset > tarfs.data_size {
+ pr_err!(
+ "inode table extends beyond the data size : {} > {}\n",
+ tarfs.inode_table_offset + (tarfs.inode_count * size_of::<Inode>() as u64),
+ tarfs.data_size,
+ );
+ return Err(E2BIG);
+ }
+
+ sb.set_magic(TARFS_MAGIC);
+ Ok(tarfs)
+ }
+
+ fn init_root(sb: &SuperBlock<Self>) -> Result<dentry::Root<Self>> {
+ let inode = Self::iget(sb, 1)?;
+ dentry::Root::try_new(inode)
+ }
+
+ fn read_xattr(
+ _: &DEntry<Self>,
+ inode: &INode<Self>,
+ name: &CStr,
+ outbuf: &mut [u8],
+ ) -> Result<usize> {
+ if inode.data().flags & inode_flags::OPAQUE == 0
+ || name.as_bytes() != b"trusted.overlay.opaque"
+ {
+ return Err(ENODATA);
+ }
+
+ if !outbuf.is_empty() {
+ outbuf[0] = b'y';
+ }
+
+ Ok(1)
+ }
+
+ fn statfs(dentry: &DEntry<Self>) -> Result<Stat> {
+ let data = dentry.super_block().data();
+ Ok(Stat {
+ magic: TARFS_MAGIC,
+ namelen: isize::MAX,
+ bsize: TARFS_BSIZE as _,
+ blocks: data.inode_table_offset / TARFS_BSIZE,
+ files: data.inode_count,
+ })
+ }
+}
+
+impl iomap::Operations for TarFs {
+ type FileSystem = Self;
+
+ fn begin<'a>(
+ inode: &'a INode<Self>,
+ pos: Offset,
+ length: Offset,
+ _flags: u32,
+ map: &mut iomap::Map<'a>,
+ _srcmap: &mut iomap::Map<'a>,
+ ) -> Result {
+ let size = (inode.size() + 511) & !511;
+ if pos >= size {
+ map.set_offset(pos)
+ .set_length(length.try_into()?)
+ .set_flags(iomap::map_flags::MERGED)
+ .set_type(iomap::Type::Hole);
+ return Ok(());
+ }
+
+ map.set_offset(pos)
+ .set_length(core::cmp::min(length, size - pos) as u64)
+ .set_flags(iomap::map_flags::MERGED)
+ .set_type(iomap::Type::Mapped)
+ .set_bdev(Some(inode.super_block().bdev()))
+ .set_addr(u64::try_from(pos)? + inode.data().offset);
+
+ Ok(())
+ }
+}
+
+#[vtable]
+impl inode::Operations for TarFs {
+ type FileSystem = Self;
+
+ fn lookup(
+ parent: &Locked<&INode<Self>, inode::ReadSem>,
+ dentry: dentry::Unhashed<'_, Self>,
+ ) -> Result<Option<ARef<DEntry<Self>>>> {
+ let sb = parent.super_block();
+ let name = dentry.name();
+
+ let inode = sb.data().mapper.for_each_page(
+ parent.data().offset.try_into()?,
+ parent.size(),
+ |data| {
+ for e in DirEntry::from_bytes_to_slice(data).ok_or(EIO)? {
+ if Self::name_eq(sb, name, e.name_offset.value())? {
+ return Ok(Some(Self::iget(sb, e.ino.value())?));
+ }
+ }
+ Ok(None)
+ },
+ )?;
+
+ dentry.splice_alias(inode)
+ }
+}
+
+#[vtable]
+impl file::Operations for TarFs {
+ type FileSystem = Self;
+
+ fn seek(file: &File<Self>, offset: Offset, whence: file::Whence) -> Result<Offset> {
+ file::generic_seek(file, offset, whence)
+ }
+
+ fn read(_: &File<Self>, _: &mut user::Writer, _: &mut Offset) -> Result<usize> {
+ Err(EISDIR)
+ }
+
+ fn read_dir(
+ _file: &File<Self>,
+ inode: &Locked<&INode<Self>, inode::ReadSem>,
+ emitter: &mut file::DirEmitter,
+ ) -> Result {
+ let sb = inode.super_block();
+ let mut name = Vec::<u8>::new();
+ let pos = emitter.pos();
+
+ if pos < 0 || pos % size_of::<DirEntry>() as i64 != 0 {
+ return Err(ENOENT);
+ }
+
+ if pos >= inode.size() {
+ return Ok(());
+ }
+
+ // Make sure the inode data doesn't overflow the data area.
+ let sizeu = u64::try_from(inode.size())?;
+ if inode.data().offset.checked_add(sizeu).ok_or(EIO)? > sb.data().data_size {
+ return Err(EIO);
+ }
+
+ sb.data().mapper.for_each_page(
+ inode.data().offset as i64 + pos,
+ inode.size() - pos,
+ |data| {
+ for e in DirEntry::from_bytes_to_slice(data).ok_or(EIO)? {
+ let name_len = usize::try_from(e.name_len.value())?;
+ if name_len > name.len() {
+ name.resize(name_len, 0, GFP_NOFS)?;
+ }
+
+ Self::read_name(sb, &mut name[..name_len], e.name_offset.value())?;
+
+ if !emitter.emit(
+ size_of::<DirEntry>() as i64,
+ &name[..name_len],
+ e.ino.value(),
+ file::DirEntryType::try_from(u32::from(e.etype))?,
+ ) {
+ return Ok(Some(()));
+ }
+ }
+ Ok(None)
+ },
+ )?;
+
+ Ok(())
+ }
+}
diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index f270c7b0cf34..6985b9e37429 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -116,7 +116,7 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
# Then, the rest outside of `rust/`.
#
# We explicitly mention the top-level folders we want to cover.
- extra_dirs = map(lambda dir: srctree / dir, ("samples", "drivers"))
+ extra_dirs = map(lambda dir: srctree / dir, ("samples", "drivers", "fs"))
if external_src is not None:
extra_dirs = [external_src]
for folder in extra_dirs:
--
2.34.1
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