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Date:   Wed, 6 Dec 2023 15:05:05 -0500
From:   Kent Overstreet <kent.overstreet@linux.dev>
To:     Christian Brauner <brauner@kernel.org>
Cc:     Alice Ryhl <aliceryhl@google.com>, Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?utf-8?B?QmrDtnJu?= Roy Baron <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arve =?utf-8?B?SGrDuG5uZXbDpWc=?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Carlos Llamas <cmllamas@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Kees Cook <keescook@chromium.org>,
        Matthew Wilcox <willy@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Daniel Xu <dxu@dxuuu.xyz>, linux-kernel@vger.kernel.org,
        rust-for-linux@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 0/7] File abstractions needed by Rust Binder
Message-ID: <20231206200505.nsmauqpetkyisyjd@moria.home.lan>
References: <20231129-alice-file-v1-0-f81afe8c7261@google.com>
 <20231129-mitsingen-umweltschutz-c6f8d9569234@brauner>
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On Wed, Nov 29, 2023 at 05:31:44PM +0100, Christian Brauner wrote:
> On Wed, Nov 29, 2023 at 12:51:06PM +0000, Alice Ryhl wrote:
> > This patchset contains the file abstractions needed by the Rust
> > implementation of the Binder driver.
> > 
> > Please see the Rust Binder RFC for usage examples:
> > https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-0-08ba9197f637@google.com/
> > 
> > Users of "rust: file: add Rust abstraction for `struct file`":
> > 	[PATCH RFC 02/20] rust_binder: add binderfs support to Rust binder
> > 	[PATCH RFC 03/20] rust_binder: add threading support
> > 
> > Users of "rust: cred: add Rust abstraction for `struct cred`":
> > 	[PATCH RFC 05/20] rust_binder: add nodes and context managers
> > 	[PATCH RFC 06/20] rust_binder: add oneway transactions
> > 	[PATCH RFC 11/20] rust_binder: send nodes in transaction
> > 	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support
> > 
> > Users of "rust: security: add abstraction for security_secid_to_secctx":
> > 	[PATCH RFC 06/20] rust_binder: add oneway transactions
> > 
> > Users of "rust: file: add `FileDescriptorReservation`":
> > 	[PATCH RFC 13/20] rust_binder: add BINDER_TYPE_FD support
> > 	[PATCH RFC 14/20] rust_binder: add BINDER_TYPE_FDA support
> > 
> > Users of "rust: file: add kuid getters":
> > 	[PATCH RFC 05/20] rust_binder: add nodes and context managers
> > 	[PATCH RFC 06/20] rust_binder: add oneway transactions
> > 
> > Users of "rust: file: add `DeferredFdCloser`":
> > 	[PATCH RFC 14/20] rust_binder: add BINDER_TYPE_FDA support
> > 
> > Users of "rust: file: add abstraction for `poll_table`":
> > 	[PATCH RFC 07/20] rust_binder: add epoll support
> > 
> > This patchset has some uses of read_volatile in place of READ_ONCE.
> > Please see the following rfc for context on this:
> > https://lore.kernel.org/all/20231025195339.1431894-1-boqun.feng@gmail.com/
> > 
> > This was previously sent as an rfc:
> > https://lore.kernel.org/all/20230720152820.3566078-1-aliceryhl@google.com/
> > 
> > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
> > ---
> > Alice Ryhl (4):
> >       rust: security: add abstraction for security_secid_to_secctx
> >       rust: file: add `Kuid` wrapper
> >       rust: file: add `DeferredFdCloser`
> >       rust: file: add abstraction for `poll_table`
> > 
> > Wedson Almeida Filho (3):
> >       rust: file: add Rust abstraction for `struct file`
> >       rust: cred: add Rust abstraction for `struct cred`
> >       rust: file: add `FileDescriptorReservation`
> > 
> >  rust/bindings/bindings_helper.h |   9 ++
> >  rust/bindings/lib.rs            |   1 +
> >  rust/helpers.c                  |  94 +++++++++++
> >  rust/kernel/cred.rs             |  73 +++++++++
> >  rust/kernel/file.rs             | 345 ++++++++++++++++++++++++++++++++++++++++
> >  rust/kernel/file/poll_table.rs  |  97 +++++++++++
> 
> That's pretty far away from the subsystem these wrappers belong to. I
> would prefer if wrappers such as this would live directly in fs/rust/
> and so live within the subsystem they belong to. I think I mentioned
> that before. Maybe I missed some sort of agreement here?

I spoke to Miguel about this and it was my understanding that everything
was in place for moving Rust wrappers to the proper directory -
previously there was build system stuff blocking, but he said that's all
working now. Perhaps the memo just didn't get passed down?

(My vote would actually be for fs/ directly, not fs/rust, and a 1:1
mapping between .c files and the .rs files that wrap them).