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From:   Kanchan Joshi <joshiiitr@gmail.com>
Date:   Tue, 21 Jul 2020 01:47:20 +0530
Message-ID: <CA+1E3rLNo5sFH3RPFAM4_SYXSmyWTCdbC3k3-6jeaj3FRPYLkQ@mail.gmail.com>
Subject: Re: [PATCH v3 4/4] io_uring: add support for zone-append
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Jens Axboe <axboe@kernel.dk>,
        Kanchan Joshi <joshi.k@samsung.com>, viro@zeniv.linux.org.uk,
        bcrl@kvack.org, Damien.LeMoal@wdc.com, asml.silence@gmail.com,
        linux-fsdevel@vger.kernel.org, "Matias Bj??rling" <mb@lightnvm.io>,
        linux-kernel@vger.kernel.org, linux-aio@kvack.org,
        io-uring@vger.kernel.org, linux-block@vger.kernel.org,
        Selvakumar S <selvakuma.s1@samsung.com>,
        Nitesh Shetty <nj.shetty@samsung.com>,
        Javier Gonzalez <javier.gonz@samsung.com>
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On Mon, Jul 20, 2020 at 10:44 PM Matthew Wilcox <willy@infradead.org> 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@gmail.com> 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.