Re: [PATCH 6/7] virtiofsd: Check EOF before short read

[Dr. David Alan Gilbert]

* Vivek Goyal (vgoyal@redhat.com) wrote:
> In virtio_send_data_iov() we are checking first for short read and then
> EOF condition. Change the order. Basically check for error and EOF first
> and last remaining piece is short ready which will lead to retry
> automatically at the end of while loop.
> 
> Just that it is little simpler to read to the code. There is no need
> to call "continue" and also one less call of "len-=ret".
> 
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  tools/virtiofsd/fuse_virtio.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
> index 434fe401cf..aa53808ef9 100644
> --- a/tools/virtiofsd/fuse_virtio.c
> +++ b/tools/virtiofsd/fuse_virtio.c
> @@ -410,25 +410,24 @@ int virtio_send_data_iov(struct fuse_session *se, 
> struct fuse_chan *ch,
>                       __func__, len);
>              goto err;
>          }
> -        fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
> -                 ret, len);
> -        if (ret < len && ret) {
> -            fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__);
> -            /* Skip over this much next time around */
> -            iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret);
> -            buf->buf[0].pos += ret;
> -            len -= ret;
>  
> -            /* Lets do another read */
> -            continue;
> -        }
>          if (!ret) {
>              /* EOF case? */
>              fuse_log(FUSE_LOG_DEBUG, "%s: !ret len remaining=%zd\n", 
> __func__,
>                       len);
>              break;
>          }
> +        fuse_log(FUSE_LOG_DEBUG, "%s: preadv ret=%d len=%zd\n", __func__,
> +                 ret, len);
> +
>          len -= ret;
> +        /* Short read. Retry reading remaining bytes */
> +        if (len) {
> +            fuse_log(FUSE_LOG_DEBUG, "%s: ret < len\n", __func__);
> +            /* Skip over this much next time around */
> +            iov_discard_front(&in_sg_ptr, &in_sg_cpy_count, ret);
> +            buf->buf[0].pos += ret;
> +        }
>      } while (len);
>  
>      /* Need to fix out->len on EOF */
> -- 
> 2.25.4
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK