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Message-ID: <20230726164535.230515-7-amiculas@cisco.com>
Date: Wed, 26 Jul 2023 19:45:30 +0300
From: Ariel Miculas <amiculas@...co.com>
To: rust-for-linux@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
tycho@...ho.pizza, brauner@...nel.org, viro@...iv.linux.org.uk,
ojeda@...nel.org, alex.gaynor@...il.com, wedsonaf@...il.com,
Ariel Miculas <amiculas@...co.com>
Subject: [RFC PATCH v2 06/10] rust: file: pass the filesystem context to the open function
This allows us to create a Vfsmount structure and pass it to the read
callback.
Signed-off-by: Ariel Miculas <amiculas@...co.com>
---
rust/kernel/file.rs | 17 +++++++++++++++--
samples/rust/puzzlefs.rs | 40 +++++++++++++++++++++++++++++++++++-----
samples/rust/rust_fs.rs | 3 ++-
3 files changed, 52 insertions(+), 8 deletions(-)
diff --git a/rust/kernel/file.rs b/rust/kernel/file.rs
index a3002c416dbb..af1eb1ee9267 100644
--- a/rust/kernel/file.rs
+++ b/rust/kernel/file.rs
@@ -457,9 +457,15 @@ impl<A: OpenAdapter<T::OpenData>, T: Operations> OperationsVtable<A, T> {
// `fileref` never outlives this function, so it is guaranteed to be
// valid.
let fileref = unsafe { File::from_ptr(file) };
+
+ // SAFETY: into_foreign was called in fs::NewSuperBlock<..., NeedsInit>::init and
+ // it is valid until from_foreign will be called in fs::Tables::free_callback
+ let fs_info =
+ unsafe { <T::Filesystem as fs::Type>::Data::borrow((*(*inode).i_sb).s_fs_info) };
+
// SAFETY: `arg` was previously returned by `A::convert` and must
// be a valid non-null pointer.
- let ptr = T::open(unsafe { &*arg }, fileref)?.into_foreign();
+ let ptr = T::open(fs_info, unsafe { &*arg }, fileref)?.into_foreign();
// SAFETY: The C contract guarantees that `private_data` is available
// for implementers of the file operations (no other C code accesses
// it), so we know that there are no concurrent threads/CPUs accessing
@@ -930,10 +936,17 @@ pub trait Operations {
/// The type of the context data passed to [`Operations::open`].
type OpenData: Sync = ();
+ /// Data associated with each file system instance.
+ type Filesystem: fs::Type;
+
/// Creates a new instance of this file.
///
/// Corresponds to the `open` function pointer in `struct file_operations`.
- fn open(context: &Self::OpenData, file: &File) -> Result<Self::Data>;
+ fn open(
+ fs_info: <<Self::Filesystem as fs::Type>::Data as ForeignOwnable>::Borrowed<'_>,
+ context: &Self::OpenData,
+ file: &File,
+ ) -> Result<Self::Data>;
/// Cleans up after the last reference to the file goes away.
///
diff --git a/samples/rust/puzzlefs.rs b/samples/rust/puzzlefs.rs
index 9afd82745b64..8a64e0bd437d 100644
--- a/samples/rust/puzzlefs.rs
+++ b/samples/rust/puzzlefs.rs
@@ -3,8 +3,14 @@
//! Rust file system sample.
use kernel::module_fs;
+use kernel::mount::Vfsmount;
use kernel::prelude::*;
-use kernel::{c_str, file, fs, io_buffer::IoBufferWriter};
+use kernel::{
+ c_str, file, fmt, fs,
+ io_buffer::IoBufferWriter,
+ str::CString,
+ sync::{Arc, ArcBorrow},
+};
mod puzzle;
// Required by the autogenerated '_capnp.rs' files
@@ -19,6 +25,12 @@
struct PuzzleFsModule;
+#[derive(Debug)]
+struct PuzzlefsInfo {
+ base_path: CString,
+ vfs_mount: Arc<Vfsmount>,
+}
+
#[vtable]
impl fs::Context<Self> for PuzzleFsModule {
type Data = ();
@@ -46,14 +58,23 @@ fn try_new() -> Result {
impl fs::Type for PuzzleFsModule {
type Context = Self;
type INodeData = &'static [u8];
+ type Data = Box<PuzzlefsInfo>;
const SUPER_TYPE: fs::Super = fs::Super::Independent;
const NAME: &'static CStr = c_str!("puzzlefs");
const FLAGS: i32 = fs::flags::USERNS_MOUNT;
const DCACHE_BASED: bool = true;
fn fill_super(_data: (), sb: fs::NewSuperBlock<'_, Self>) -> Result<&fs::SuperBlock<Self>> {
+ let base_path = CString::try_from_fmt(fmt!("hello world"))?;
+ pr_info!("base_path {:?}\n", base_path);
+ let vfs_mount = Vfsmount::new_private_mount(c_str!("/home/puzzlefs_oci"))?;
+ pr_info!("vfs_mount {:?}\n", vfs_mount);
+
let sb = sb.init(
- (),
+ Box::try_new(PuzzlefsInfo {
+ base_path,
+ vfs_mount: Arc::try_new(vfs_mount)?,
+ })?,
&fs::SuperParams {
magic: 0x72757374,
..fs::SuperParams::DEFAULT
@@ -88,14 +109,23 @@ fn fill_super(_data: (), sb: fs::NewSuperBlock<'_, Self>) -> Result<&fs::SuperBl
#[vtable]
impl file::Operations for FsFile {
+ // must be the same as INodeData
type OpenData = &'static [u8];
+ type Filesystem = PuzzleFsModule;
+ // this is an Arc because Data must be ForeignOwnable and the only implementors of it are Box,
+ // Arc and (); we cannot pass a reference to read, so we share Vfsmount using and Arc
+ type Data = Arc<Vfsmount>;
- fn open(_context: &Self::OpenData, _file: &file::File) -> Result<Self::Data> {
- Ok(())
+ fn open(
+ fs_info: &PuzzlefsInfo,
+ _context: &Self::OpenData,
+ _file: &file::File,
+ ) -> Result<Self::Data> {
+ Ok(fs_info.vfs_mount.clone())
}
fn read(
- _data: (),
+ data: ArcBorrow<'_, Vfsmount>,
file: &file::File,
writer: &mut impl IoBufferWriter,
offset: u64,
diff --git a/samples/rust/rust_fs.rs b/samples/rust/rust_fs.rs
index 7527681ee024..c58ed1560e06 100644
--- a/samples/rust/rust_fs.rs
+++ b/samples/rust/rust_fs.rs
@@ -85,8 +85,9 @@ fn fill_super(_data: (), sb: fs::NewSuperBlock<'_, Self>) -> Result<&fs::SuperBl
#[vtable]
impl file::Operations for FsFile {
type OpenData = &'static [u8];
+ type Filesystem = RustFs;
- fn open(_context: &Self::OpenData, _file: &file::File) -> Result<Self::Data> {
+ fn open(_fs_info: (), _context: &Self::OpenData, _file: &file::File) -> Result<Self::Data> {
Ok(())
}
--
2.41.0
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