Re: [PATCH for-next v4 1/4] io_uring: introduce io_uring_cmd_import_fixed

[Jens Axboe <axboe@kernel.dk>]

On 9/5/22 7:48 AM, Kanchan Joshi wrote:
> From: Anuj Gupta <anuj20.g@samsung.com>
> 
> This is a new helper that callers can use to obtain a bvec iterator for
> the previously mapped buffer. This is preparatory work to enable
> fixed-buffer support for io_uring_cmd.
> 
> Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> ---
>  include/linux/io_uring.h |  8 ++++++++
>  io_uring/uring_cmd.c     | 11 +++++++++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
> index 58676c0a398f..dba6fb47aa6c 100644
> --- a/include/linux/io_uring.h
> +++ b/include/linux/io_uring.h
> @@ -4,6 +4,7 @@
>  
>  #include <linux/sched.h>
>  #include <linux/xarray.h>
> +#include <uapi/linux/io_uring.h>
>  
>  enum io_uring_cmd_flags {
>  	IO_URING_F_COMPLETE_DEFER	= 1,
> @@ -32,6 +33,8 @@ struct io_uring_cmd {
>  };
>  
>  #if defined(CONFIG_IO_URING)
> +int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
> +		struct iov_iter *iter, void *ioucmd);
>  void io_uring_cmd_done(struct io_uring_cmd *cmd, ssize_t ret, ssize_t res2);
>  void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
>  			void (*task_work_cb)(struct io_uring_cmd *));
> @@ -59,6 +62,11 @@ static inline void io_uring_free(struct task_struct *tsk)
>  		__io_uring_free(tsk);
>  }
>  #else
> +int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw,
> +		struct iov_iter *iter, void *ioucmd)
> +{
> +	return -1;
> +}

Is this right? Shouldn't it return -EOPNOTSUPP or another suitable actual
error value?

Apart from that, I think the patchset looks fine now.

-- 
Jens Axboe