iscsi: Switch .bdrv_co_discard() to byte-based
Another step towards killing off sector-based block APIs.
Unlike write_zeroes, where we can be handed unaligned requests
and must fail gracefully with -ENOTSUP for a fallback, we are
guaranteed that discard requests are always aligned because the
block layer already ignored unaligned head/tail.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id:
1468624988-423-13-git-send-email-eblake@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>