Re: [PATCH 0/7] File abstractions needed by Rust Binder

[Kent Overstreet]

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@xxxxxxxxxx/
> > 
> > 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@xxxxxxxxx/
> > 
> > This was previously sent as an rfc:
> > https://lore.kernel.org/all/20230720152820.3566078-1-aliceryhl@xxxxxxxxxx/
> > 
> > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > ---
> > 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).