[PATCH v3 0/4] Rust support for `struct iov_iter`

[Alice Ryhl]

This series adds support for the `struct iov_iter` type. This type
represents an IO buffer for reading or writing, and can be configured
for either direction of communication.

In Rust, we define separate types for reading and writing. This will
ensure that you cannot mix them up and e.g. call copy_from_iter in a
read_iter syscall.

To use the new abstractions, miscdevices are given new methods read_iter
and write_iter that can be used to implement the read/write syscalls on
a miscdevice. The miscdevice sample is updated to provide read/write
operations.

Based on rust-next for this dependency:
https://lore.kernel.org/all/20250612-pointed-to-v3-0-b009006d86a1@xxxxxxxxxx/

Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
---
Changes in v3:
- Rebase on rust-next.
- Use ptr::from_mut to silence warning.
- Move Kiocb to rust::fs.
- Rename Kiocb::device() to Kiocb::file() as it's no longer miscdevice
  specific.
- Significant rewording of docs and safety comments, especially patch 1
  and 2.
- Link to v2: https://lore.kernel.org/r/20250704-iov-iter-v2-0-e69aa7c1f40e@xxxxxxxxxx

Changes in v2:
- Remove Send/Sync/Copy impls.
- Reword docs significantly.
- Rename Kiocb::private_data() to Kiocb::device().
- Rebase on v6.16-rc2.
- Link to v1: https://lore.kernel.org/r/20250311-iov-iter-v1-0-f6c9134ea824@xxxxxxxxxx

---
Alice Ryhl (3):
      rust: iov: add iov_iter abstractions for ITER_SOURCE
      rust: iov: add iov_iter abstractions for ITER_DEST
      rust: miscdevice: Provide additional abstractions for iov_iter and kiocb structures

Lee Jones (1):
      samples: rust_misc_device: Expand the sample to support read()ing from userspace

 rust/kernel/fs.rs                |   3 +
 rust/kernel/fs/kiocb.rs          |  67 +++++++++
 rust/kernel/iov.rs               | 310 +++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs               |   1 +
 rust/kernel/miscdevice.rs        |  63 +++++++-
 samples/rust/rust_misc_device.rs |  36 ++++-
 6 files changed, 477 insertions(+), 3 deletions(-)
---
base-commit: 07dad44aa9a93b16af19e8609a10b241c352b440
change-id: 20250311-iov-iter-c984aea07d18

Best regards,
-- 
Alice Ryhl <aliceryhl@xxxxxxxxxx>