From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH v3 17/18] vhost: don't bother copying iovecs in
	handle_rx(), kill memcpy_toiovecend()
Date: Wed, 4 Feb 2015 10:02:27 +0100
Message-ID: <20150204090227.GC9920@redhat.com>
References: <20150204063730.GG29656@ZenIV.linux.org.uk>
	<1423032009-18367-17-git-send-email-viro@ZenIV.linux.org.uk>
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Cc: netdev@vger.kernel.org, David Miller <davem@davemloft.net>,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
To: Al Viro <viro@ZenIV.linux.org.uk>
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>  		if (likely(mergeable) &&
> -		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
> -				      offsetof(typeof(hdr), num_buffers),
> -				      sizeof hdr.num_buffers)) {
> +		    copy_to_iter(&headcount, 2, &fixup) != 2) {
>  			vq_err(vq, "Failed num_buffers write");
>  			vhost_discard_vq_desc(vq, headcount);
>  			break;

BTW this will have to be re-based on top of
http://mid.gmane.org/1422896842-19186-1-git-send-email-mst@redhat.com
taking byte-swap into account.