Re: [PATCH v3 4/4] io_uring: add support for zone-append

[Kanchan Joshi]

On Mon, Jul 20, 2020 at 10:44 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Mon, Jul 20, 2020 at 10:19:57PM +0530, Kanchan Joshi wrote:
> > On Fri, Jul 10, 2020 at 7:41 PM Kanchan Joshi <joshiiitr@xxxxxxxxx> wrote:
> > > If we are doing this for zone-append (and not general cases), "__s64
> > > res64" should work -.
> > > 64 bits = 1 (sign) + 23 (bytes-copied: cqe->res) + 40
> > > (written-location: chunk_sector bytes limit)
>
> No, don't do this.
>
>  struct io_uring_cqe {
>         __u64   user_data;      /* sqe->data submission passed back */
> -       __s32   res;            /* result code for this event */
> -       __u32   flags;
> +       union {
> +               struct {
> +                       __s32   res;    /* result code for this event */
> +                       __u32   flags;
> +               };
> +               __s64           res64;
> +       };
>  };
>
> Return the value in bytes in res64, or a negative errno.  Done.

I concur. Can do away with bytes-copied. It's either in its entirety
or not at all.