From: Wedson Almeida Filho <wedsonaf@gmail.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Dave Chinner <david@fromorbit.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-fsdevel@vger.kernel.org, rust-for-linux@vger.kernel.org,
linux-kernel@vger.kernel.org,
Wedson Almeida Filho <walmeida@microsoft.com>
Subject: [RFC PATCH v2 13/30] rust: fs: introduce `file::Operations::read`
Date: Tue, 14 May 2024 10:16:54 -0300 [thread overview]
Message-ID: <20240514131711.379322-14-wedsonaf@gmail.com> (raw)
In-Reply-To: <20240514131711.379322-1-wedsonaf@gmail.com>
From: Wedson Almeida Filho <walmeida@microsoft.com>
This allows file systems to customise their behaviour when callers want
to read from a file.
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
---
rust/kernel/fs/file.rs | 35 ++++++++++++++++++++++++++++++++++-
rust/kernel/user.rs | 1 -
samples/rust/rust_rofs.rs | 6 +++++-
3 files changed, 39 insertions(+), 3 deletions(-)
diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs
index 77eb6d230568..2ba456a1eee1 100644
--- a/rust/kernel/fs/file.rs
+++ b/rust/kernel/fs/file.rs
@@ -12,6 +12,7 @@
bindings,
error::{code::*, from_result, Error, Result},
types::{ARef, AlwaysRefCounted, Locked, Opaque},
+ user,
};
use core::{marker::PhantomData, mem::ManuallyDrop, ptr};
use macros::vtable;
@@ -324,6 +325,15 @@ pub trait Operations {
/// File system that these operations are compatible with.
type FileSystem: FileSystem + ?Sized;
+ /// Reads data from this file into the caller's buffer.
+ fn read(
+ _file: &File<Self::FileSystem>,
+ _buffer: &mut user::Writer,
+ _offset: &mut Offset,
+ ) -> Result<usize> {
+ Err(EINVAL)
+ }
+
/// Seeks the file to the given offset.
fn seek(_file: &File<Self::FileSystem>, _offset: Offset, _whence: Whence) -> Result<Offset> {
Err(EINVAL)
@@ -356,7 +366,11 @@ impl<T: Operations + ?Sized> Table<T> {
} else {
None
},
- read: None,
+ read: if T::HAS_READ {
+ Some(Self::read_callback)
+ } else {
+ None
+ },
write: None,
read_iter: None,
write_iter: None,
@@ -407,6 +421,25 @@ impl<T: Operations + ?Sized> Table<T> {
})
}
+ unsafe extern "C" fn read_callback(
+ file_ptr: *mut bindings::file,
+ ptr: *mut core::ffi::c_char,
+ len: usize,
+ offset: *mut bindings::loff_t,
+ ) -> isize {
+ from_result(|| {
+ // SAFETY: The C API guarantees that `file` is valid for the duration of the
+ // callback. Since this callback is specifically for filesystem T, we know `T`
+ // is the right filesystem.
+ let file = unsafe { File::from_raw(file_ptr) };
+ let mut writer = user::Writer::new(ptr, len);
+
+ // SAFETY: The C API guarantees that `offset` is valid for read and write.
+ let read = T::read(file, &mut writer, unsafe { &mut *offset })?;
+ Ok(isize::try_from(read)?)
+ })
+ }
+
unsafe extern "C" fn read_dir_callback(
file_ptr: *mut bindings::file,
ctx_ptr: *mut bindings::dir_context,
diff --git a/rust/kernel/user.rs b/rust/kernel/user.rs
index 35a673ebcd58..20fb887f4640 100644
--- a/rust/kernel/user.rs
+++ b/rust/kernel/user.rs
@@ -11,7 +11,6 @@ pub struct Writer {
}
impl Writer {
- #[allow(dead_code)]
pub(crate) fn new(ptr: *mut i8, len: usize) -> Self {
Self {
ptr: ptr.cast::<u8>(),
diff --git a/samples/rust/rust_rofs.rs b/samples/rust/rust_rofs.rs
index abec084360da..f4be5908369c 100644
--- a/samples/rust/rust_rofs.rs
+++ b/samples/rust/rust_rofs.rs
@@ -4,7 +4,7 @@
use kernel::fs::{dentry, file, file::File, inode, inode::INode, sb::SuperBlock, Offset};
use kernel::prelude::*;
-use kernel::{c_str, fs, time::UNIX_EPOCH, types::Either, types::Locked};
+use kernel::{c_str, fs, time::UNIX_EPOCH, types::Either, types::Locked, user};
kernel::module_fs! {
type: RoFs,
@@ -80,6 +80,10 @@ fn seek(file: &File<Self>, offset: Offset, whence: file::Whence) -> Result<Offse
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>,
--
2.34.1
next prev parent reply other threads:[~2024-05-14 13:17 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-14 13:16 [RFC PATCH v2 00/30] Rust abstractions for VFS Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 01/30] rust: fs: add registration/unregistration of file systems Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 02/30] rust: fs: introduce the `module_fs` macro Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 03/30] samples: rust: add initial ro file system sample Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 04/30] rust: fs: introduce `FileSystem::fill_super` Wedson Almeida Filho
2024-05-20 19:38 ` Darrick J. Wong
2024-05-14 13:16 ` [RFC PATCH v2 05/30] rust: fs: introduce `INode<T>` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 06/30] rust: fs: introduce `DEntry<T>` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 07/30] rust: fs: introduce `FileSystem::init_root` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 08/30] rust: file: move `kernel::file` to `kernel::fs::file` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 09/30] rust: fs: generalise `File` for different file systems Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 10/30] rust: fs: add empty file operations Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 11/30] rust: fs: introduce `file::Operations::read_dir` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 12/30] rust: fs: introduce `file::Operations::seek` Wedson Almeida Filho
2024-05-14 13:16 ` Wedson Almeida Filho [this message]
2024-05-14 13:16 ` [RFC PATCH v2 14/30] rust: fs: add empty inode operations Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 15/30] rust: fs: introduce `inode::Operations::lookup` Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 16/30] rust: folio: introduce basic support for folios Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 17/30] rust: fs: add empty address space operations Wedson Almeida Filho
2024-05-14 13:16 ` [RFC PATCH v2 18/30] rust: fs: introduce `address_space::Operations::read_folio` Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 19/30] rust: fs: introduce `FileSystem::read_xattr` Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 20/30] rust: fs: introduce `FileSystem::statfs` Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 21/30] rust: fs: introduce more inode types Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 22/30] rust: fs: add per-superblock data Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 23/30] rust: fs: allow file systems backed by a block device Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 24/30] rust: fs: allow per-inode data Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 25/30] rust: fs: export file type from mode constants Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 26/30] rust: fs: allow populating i_lnk Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 27/30] rust: fs: add `iomap` module Wedson Almeida Filho
2024-05-20 19:32 ` Darrick J. Wong
2024-05-14 13:17 ` [RFC PATCH v2 28/30] rust: fs: add memalloc_nofs support Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 29/30] tarfs: introduce tar fs Wedson Almeida Filho
2024-05-14 13:17 ` [RFC PATCH v2 30/30] WIP: fs: ext2: add rust ro ext2 implementation Wedson Almeida Filho
2024-05-20 20:01 ` Darrick J. Wong
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