From 5e15de179a204ce26623d8468283ac04a0dc672f Mon Sep 17 00:00:00 2001
From: Alice Ryhl <aliceryhl@google.com>
Date: Fri, 22 Aug 2025 08:42:34 +0000
Subject: rust: fs: add Kiocb struct

This adds a very simple Kiocb struct that lets you access the inner
file's private data and the file position. For now, nothing else is
supported.

Cc: Christian Brauner <brauner@kernel.org>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250822-iov-iter-v5-3-6ce4819c2977@google.com
---
 rust/kernel/fs/kiocb.rs | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 rust/kernel/fs/kiocb.rs

(limited to 'rust/kernel/fs')

diff --git a/rust/kernel/fs/kiocb.rs b/rust/kernel/fs/kiocb.rs
new file mode 100644
index 000000000000..84c936cd69b0
--- /dev/null
+++ b/rust/kernel/fs/kiocb.rs
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2024 Google LLC.
+
+//! Kernel IO callbacks.
+//!
+//! C headers: [`include/linux/fs.h`](srctree/include/linux/fs.h)
+
+use core::marker::PhantomData;
+use core::ptr::NonNull;
+use kernel::types::ForeignOwnable;
+
+/// Wrapper for the kernel's `struct kiocb`.
+///
+/// Currently this abstractions is incomplete and is essentially just a tuple containing a
+/// reference to a file and a file position.
+///
+/// The type `T` represents the filesystem or driver specific data associated with the file.
+///
+/// # Invariants
+///
+/// `inner` points at a valid `struct kiocb` whose file has the type `T` as its private data.
+pub struct Kiocb<'a, T> {
+    inner: NonNull<bindings::kiocb>,
+    _phantom: PhantomData<&'a T>,
+}
+
+impl<'a, T: ForeignOwnable> Kiocb<'a, T> {
+    /// Create a `Kiocb` from a raw pointer.
+    ///
+    /// # Safety
+    ///
+    /// The pointer must reference a valid `struct kiocb` for the duration of `'a`. The private
+    /// data of the file must be `T`.
+    pub unsafe fn from_raw(kiocb: *mut bindings::kiocb) -> Self {
+        Self {
+            // SAFETY: If a pointer is valid it is not null.
+            inner: unsafe { NonNull::new_unchecked(kiocb) },
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Access the underlying `struct kiocb` directly.
+    pub fn as_raw(&self) -> *mut bindings::kiocb {
+        self.inner.as_ptr()
+    }
+
+    /// Get the filesystem or driver specific data associated with the file.
+    pub fn file(&self) -> <T as ForeignOwnable>::Borrowed<'a> {
+        // SAFETY: We have shared access to this kiocb and hence the underlying file, so we can
+        // read the file's private data.
+        let private = unsafe { (*(*self.as_raw()).ki_filp).private_data };
+        // SAFETY: The kiocb has shared access to the private data.
+        unsafe { <T as ForeignOwnable>::borrow(private) }
+    }
+
+    /// Gets the current value of `ki_pos`.
+    pub fn ki_pos(&self) -> i64 {
+        // SAFETY: We have shared access to the kiocb, so we can read its `ki_pos` field.
+        unsafe { (*self.as_raw()).ki_pos }
+    }
+
+    /// Gets a mutable reference to the `ki_pos` field.
+    pub fn ki_pos_mut(&mut self) -> &mut i64 {
+        // SAFETY: We have exclusive access to the kiocb, so we can write to `ki_pos`.
+        unsafe { &mut (*self.as_raw()).ki_pos }
+    }
+}
-- 
cgit 


From d68a29a6a229f8b4f3b19dbcd0bb02881316d642 Mon Sep 17 00:00:00 2001
From: Tong Li <djfkvcing117@gmail.com>
Date: Tue, 30 Sep 2025 19:02:58 +0800
Subject: rust: file: add intra-doc link for 'EBADF'
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The `BadFdError` doc comment mentions the `EBADF` constant but does
not currently provide a navigation target for readers of the
generated docs. Turning the references into intra-doc links matches
the rest of the module and makes the documentation easier to
explore.

Suggested-by: Onur Özkan <work@onurozkan.dev>
Link: https://github.com/Rust-for-Linux/linux/issues/1186
Signed-off-by: Tong Li <djfkvcing117@gmail.com>
Reviewed-by: Onur Özkan <work@onurozkan.dev>
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 rust/kernel/fs/file.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'rust/kernel/fs')

diff --git a/rust/kernel/fs/file.rs b/rust/kernel/fs/file.rs
index cf06e73a6da0..cd6987850332 100644
--- a/rust/kernel/fs/file.rs
+++ b/rust/kernel/fs/file.rs
@@ -448,9 +448,9 @@ impl Drop for FileDescriptorReservation {
     }
 }
 
-/// Represents the `EBADF` error code.
+/// Represents the [`EBADF`] error code.
 ///
-/// Used for methods that can only fail with `EBADF`.
+/// Used for methods that can only fail with [`EBADF`].
 #[derive(Copy, Clone, Eq, PartialEq)]
 pub struct BadFdError;
 
-- 
cgit