Re: [RFC PATCH 1/5] rust: block: introduce `kernel::block::mq` module

[Boqun Feng <boqun.feng@gmail.com>]

On Wed, Mar 13, 2024 at 12:05:08PM +0100, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@samsung.com>
> 
> Add initial abstractions for working with blk-mq.
> 
> This patch is a maintained, refactored subset of code originally published by
> Wedson Almeida Filho <wedsonaf@gmail.com> [1].
> 
> [1] https://github.com/wedsonaf/linux/tree/f2cfd2fe0e2ca4e90994f96afe268bbd4382a891/rust/kernel/blk/mq.rs
> 
> Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
> ---
>  block/blk-mq.c                     |   3 +-
>  include/linux/blk-mq.h             |   1 +
>  rust/bindings/bindings_helper.h    |   2 +
>  rust/helpers.c                     |  45 ++++
>  rust/kernel/block.rs               |   5 +
>  rust/kernel/block/mq.rs            | 131 +++++++++++
>  rust/kernel/block/mq/gen_disk.rs   | 174 +++++++++++++++
>  rust/kernel/block/mq/operations.rs | 346 +++++++++++++++++++++++++++++
>  rust/kernel/block/mq/raw_writer.rs |  60 +++++
>  rust/kernel/block/mq/request.rs    | 182 +++++++++++++++
>  rust/kernel/block/mq/tag_set.rs    | 117 ++++++++++
>  rust/kernel/error.rs               |   5 +
>  rust/kernel/lib.rs                 |   1 +
>  13 files changed, 1071 insertions(+), 1 deletion(-)
>  create mode 100644 rust/kernel/block.rs
>  create mode 100644 rust/kernel/block/mq.rs
>  create mode 100644 rust/kernel/block/mq/gen_disk.rs
>  create mode 100644 rust/kernel/block/mq/operations.rs
>  create mode 100644 rust/kernel/block/mq/raw_writer.rs
>  create mode 100644 rust/kernel/block/mq/request.rs
>  create mode 100644 rust/kernel/block/mq/tag_set.rs
> 
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 2dc01551e27c..a531f664bee7 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -702,7 +702,7 @@ static void blk_mq_finish_request(struct request *rq)
>  	}
>  }
>  
> -static void __blk_mq_free_request(struct request *rq)
> +void __blk_mq_free_request(struct request *rq)
>  {
>  	struct request_queue *q = rq->q;
>  	struct blk_mq_ctx *ctx = rq->mq_ctx;
> @@ -722,6 +722,7 @@ static void __blk_mq_free_request(struct request *rq)
>  	blk_mq_sched_restart(hctx);
>  	blk_queue_exit(q);
>  }
> +EXPORT_SYMBOL_GPL(__blk_mq_free_request);
>  

Note that for an EXPORT_SYMBOL_GPL() symbol, you can just add the
corresponding header file in rust/bindings/bindings_helper.h:

+#include <linux/blk-mq.h>

and you will be able to call it from Rust via:

	bindings::__blk_mq_free_request()

in other words, rust_helper_blk_mq_free_request_internal() is probably
not necessary.

Regards,
Boqun

>  void blk_mq_free_request(struct request *rq)
>  {
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index 7a8150a5f051..842bb88e6e78 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -703,6 +703,7 @@ int blk_mq_alloc_sq_tag_set(struct blk_mq_tag_set *set,
>  		unsigned int set_flags);
>  void blk_mq_free_tag_set(struct blk_mq_tag_set *set);
>  
> +void __blk_mq_free_request(struct request *rq);
>  void blk_mq_free_request(struct request *rq);
>  int blk_rq_poll(struct request *rq, struct io_comp_batch *iob,
>  		unsigned int poll_flags);
> diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
> index f8e54d398c19..df18acb229d9 100644
> --- a/rust/bindings/bindings_helper.h
> +++ b/rust/bindings/bindings_helper.h
> @@ -7,6 +7,8 @@
>   */
>  
>  #include <kunit/test.h>
> +#include <linux/blk_types.h>
> +#include <linux/blk-mq.h>
>  #include <linux/errname.h>
>  #include <linux/ethtool.h>
>  #include <linux/mdio.h>
> diff --git a/rust/helpers.c b/rust/helpers.c
> index 66411845536e..017fa90366e6 100644
> --- a/rust/helpers.c
> +++ b/rust/helpers.c
> @@ -21,6 +21,9 @@
>   */
>  
[...]
> +
> +void rust_helper_blk_mq_free_request_internal(struct request *req)
> +{
> +	__blk_mq_free_request(req);
> +}
> +EXPORT_SYMBOL_GPL(rust_helper_blk_mq_free_request_internal);
> +
[...]