Re: [PATCH v2 3/8] fuse: refactor io-uring header copying to ring

[Bernd Schubert <bschubert@ddn.com>]

On 10/27/25 23:28, Joanne Koong wrote:
> Move header copying to ring logic into a new copy_header_to_ring()
> function. This consolidates error handling.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> ---
>  fs/fuse/dev_uring.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index 415924b346c0..e94af90d4d46 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -574,6 +574,17 @@ static int fuse_uring_out_header_has_err(struct fuse_out_header *oh,
>  	return err;
>  }
>  
> +static int copy_header_to_ring(void __user *ring, const void *header,
> +			       size_t header_size)
> +{
> +	if (copy_to_user(ring, header, header_size)) {
> +		pr_info_ratelimited("Copying header to ring failed.\n");
> +		return -EFAULT;
> +	}
> +
> +	return 0;
> +}
> +
>  static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
>  				     struct fuse_req *req,
>  				     struct fuse_ring_ent *ent)
> @@ -634,13 +645,11 @@ static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,
>  		 * Some op code have that as zero size.
>  		 */
>  		if (args->in_args[0].size > 0) {
> -			err = copy_to_user(&ent->headers->op_in, in_args->value,
> -					   in_args->size);
> -			if (err) {
> -				pr_info_ratelimited(
> -					"Copying the header failed.\n");
> -				return -EFAULT;
> -			}
> +			err = copy_header_to_ring(&ent->headers->op_in,
> +						  in_args->value,
> +						  in_args->size);
> +			if (err)
> +				return err;
>  		}
>  		in_args++;
>  		num_args--;
> @@ -655,9 +664,8 @@ static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,
>  	}
>  
>  	ent_in_out.payload_sz = cs.ring.copied_sz;
> -	err = copy_to_user(&ent->headers->ring_ent_in_out, &ent_in_out,
> -			   sizeof(ent_in_out));
> -	return err ? -EFAULT : 0;
> +	return copy_header_to_ring(&ent->headers->ring_ent_in_out, &ent_in_out,
> +				   sizeof(ent_in_out));
>  }
>  
>  static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,
> @@ -686,14 +694,8 @@ static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,
>  	}
>  
>  	/* copy fuse_in_header */
> -	err = copy_to_user(&ent->headers->in_out, &req->in.h,
> -			   sizeof(req->in.h));
> -	if (err) {
> -		err = -EFAULT;
> -		return err;
> -	}
> -
> -	return 0;
> +	return copy_header_to_ring(&ent->headers->in_out, &req->in.h,
> +				   sizeof(req->in.h));
>  }

This will give Miklos a bit headache, because of a merge conflict with

https://lore.kernel.org/r/20251021-io-uring-fixes-copy-finish-v1-1-913ecf8aa945@ddn.com

Any chance you could rebase your series on this patch?

Thanks,
Bernd

>  
>  static int fuse_uring_prepare_send(struct fuse_ring_ent *ent,