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

[Joanne Koong <joannelkoong@gmail.com>]

On Thu, Oct 30, 2025 at 4:15 PM Bernd Schubert <bschubert@ddn.com> wrote:
>
> 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?

Definitely, I will do that for v3. I saw that you submitted a bunch of
io-uring patches earlier last week alongside this one -  I haven't
gotten around to reviewing those but I will do so.

Thanks,
Joanne
>
> Thanks,
> Bernd
>
> >
> >  static int fuse_uring_prepare_send(struct fuse_ring_ent *ent,
>
>