On Mon, 2023-08-28 at 09:23 -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> Jeff confirmed his original fix addressed his pynfs test failure,
> but this same bug also impacted qemu: accessing qcow2 virtual disks
> using direct I/O was failing. Jeff's fix missed that you have to
> shorten the bio_vec element by the same amount as you increased
> the page offset.
>
> Reported-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> Fixes: c96e2a695e00 ("sunrpc: set the bv_offset of first bvec in svc_tcp_sendmsg")
> Tested-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> net/sunrpc/svcsock.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> v2:
> - Correct Maxim's email addresses.
>
> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> index 2eb8df44f894..589020ed909d 100644
> --- a/net/sunrpc/svcsock.c
> +++ b/net/sunrpc/svcsock.c
> @@ -1244,8 +1244,10 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
> if (ret != head->iov_len)
> goto out;
>
> - if (xdr_buf_pagecount(xdr))
> + if (xdr_buf_pagecount(xdr)) {
> xdr->bvec[0].bv_offset = offset_in_page(xdr->page_base);
> + xdr->bvec[0].bv_len -= offset_in_page(xdr->page_base);
> + }
>
> msg.msg_flags = MSG_SPLICE_PAGES;
> iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, xdr->bvec,
>
>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
