[Libguestfs] [libnbd PATCH 4/4] api: Add DF flag support for pread

[Richard W.M. Jones]

On Mon, May 27, 2019 at 09:01:01PM -0500, Eric Blake wrote:
> diff --git a/lib/rw.c b/lib/rw.c
> index feaf468..343c340 100644
> --- a/lib/rw.c
> +++ b/lib/rw.c
> @@ -234,11 +234,17 @@ int64_t
>  nbd_unlocked_aio_pread (struct nbd_handle *h, void *buf,
>                          size_t count, uint64_t offset, uint32_t flags)
>  {
> -  if (flags != 0) {
> +  if ((flags & ~LIBNBD_CMD_FLAG_DF) != 0) {
>      set_error (EINVAL, "invalid flag: %" PRIu32, flags);
>      return -1;
>    }
> 
> +  if ((flags & LIBNBD_CMD_FLAG_DF) != 0 &&
> +      nbd_unlocked_can_df (h) != 1) {
> +    set_error (EINVAL, "server does not support the DF flag");
> +    return -1;
> +  }

I'm confused why you'd want to specify this flag to pread.  From the
caller point of view they shouldn't care about whether the reply on
the wire is fragmented or not?

(I can understand why you'd need this flag if we implemented a
separate structured_pread call.)

Rich.

-- 
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