Re: [PATCH v2 03/14] fuse: refactor io-uring header copying from ring

[Jeff Layton <jlayton@kernel.org>]

On Thu, 2026-04-02 at 09:28 -0700, Joanne Koong wrote:
> Move header copying from ring logic into a new copy_header_from_ring()
> function. This makes the copy_from_user() logic more clear and
> centralizes error handling / rate-limited logging.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> Reviewed-by: Bernd Schubert <bschubert@ddn.com>
> ---
>  fs/fuse/dev_uring.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index 5fc8ca330595..86f9bb94b45a 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -587,6 +587,18 @@ static __always_inline int copy_header_to_ring(void __user *ring,
>  	return 0;
>  }
>  
> +static __always_inline int copy_header_from_ring(void *header,
> +						 const void __user *ring,
> +						 size_t header_size)
> +{
> +	if (copy_from_user(header, ring, header_size)) {
> +		pr_info_ratelimited("Copying header from 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)
> @@ -597,10 +609,10 @@ static int fuse_uring_copy_from_ring(struct fuse_ring *ring,
>  	int err;
>  	struct fuse_uring_ent_in_out ring_in_out;
>  
> -	err = copy_from_user(&ring_in_out, &ent->headers->ring_ent_in_out,
> -			     sizeof(ring_in_out));
> +	err = copy_header_from_ring(&ring_in_out, &ent->headers->ring_ent_in_out,
> +				    sizeof(ring_in_out));
>  	if (err)
> -		return -EFAULT;
> +		return err;
>  
>  	err = import_ubuf(ITER_SOURCE, ent->payload, ring->max_payload_sz,
>  			  &iter);
> @@ -794,10 +806,10 @@ static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req,
>  	struct fuse_conn *fc = ring->fc;
>  	ssize_t err = 0;
>  
> -	err = copy_from_user(&req->out.h, &ent->headers->in_out,
> -			     sizeof(req->out.h));
> +	err = copy_header_from_ring(&req->out.h, &ent->headers->in_out,
> +				    sizeof(req->out.h));
>  	if (err) {
> -		req->out.h.error = -EFAULT;
> +		req->out.h.error = err;
>  		goto out;
>  	}
>  

Reviewed-by: Jeff Layton <jlayton@kernel.org>