From: Pekka Ristola <pekkarr@protonmail.com>
Date: Tue, 27 May 2025 20:48:55 +0000 (+0000)
Subject: rust: file: mark `LocalFile` as `repr(transparent)`
X-Git-Tag: v6.16-rc1~77^2~1^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=15ecd83dc06277385ad71dc7ea26911d9a79acaf;p=thirdparty%2Fkernel%2Flinux.git

rust: file: mark `LocalFile` as `repr(transparent)`

Unsafe code in `LocalFile`'s methods assumes that the type has the same
layout as the inner `bindings::file`. This is not guaranteed by the default
struct representation in Rust, but requires specifying the `transparent`
representation.

The `File` struct (which also wraps `bindings::file`) is already marked as
`repr(transparent)`, so this change makes their layouts equivalent.

Fixes: 851849824bb5 ("rust: file: add Rust abstraction for `struct file`")
Closes: https://github.com/Rust-for-Linux/linux/issues/1165
Signed-off-by: Pekka Ristola <pekkarr@protonmail.com>
Link: https://lore.kernel.org/20250527204636.12573-1-pekkarr@protonmail.com
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---

diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs
index 13a0e44cd1aa8..138693bdeb3fd 100644
--- a/rust/kernel/fs/file.rs
+++ b/rust/kernel/fs/file.rs
@@ -219,6 +219,7 @@ unsafe impl AlwaysRefCounted for File {
 ///   must be on the same thread as this file.
 ///
 /// [`assume_no_fdget_pos`]: LocalFile::assume_no_fdget_pos
+#[repr(transparent)]
 pub struct LocalFile {
     inner: Opaque<bindings::file>,
 }