[PATCH 1/2] rust: file: mark `LocalFile` as `repr(transparent)`

[Pekka Ristola <pekkarr@protonmail.com>]

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>
---
 rust/kernel/fs/file.rs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs
index 13a0e44cd1aa..138693bdeb3f 100644
--- a/rust/kernel/fs/file.rs
+++ b/rust/kernel/fs/file.rs
@@ -219,6 +219,7 @@ unsafe fn dec_ref(obj: ptr::NonNull<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>,
 }
-- 
2.49.0