Commit 24abdf1b authored Feb 08, 2017 by Chuck Lever Committed by Anna Schumaker Feb 10, 2017

xprtrdma: Fix Read chunk padding



When pad optimization is disabled, rpcrdma_convert_iovs still
does not add explicit XDR round-up padding to a Read chunk.

Commit 677eb17e ("xprtrdma: Fix XDR tail buffer marshalling")
incorrectly short-circuited the test for whether round-up padding
is needed that appears later in rpcrdma_convert_iovs.

However, if this is indeed a regular Read chunk (and not a
Position-Zero Read chunk), the tail iovec _always_ contains the
chunk's padding, and never anything else.

So, it's easy to just skip the tail when padding optimization is
enabled, and add the tail in a subsequent Read chunk segment, if
disabled.

Fixes: 677eb17e ("xprtrdma: Fix XDR tail buffer marshalling")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

parent 26ae102f

net/sunrpc/xprtrdma/rpc_rdma.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -226,8 +226,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
		if (len && n == RPCRDMA_MAX_SEGS)
		goto out_overflow;

		/* When encoding the read list, the tail is always sent inline */
		if (type == rpcrdma_readch)
		/* When encoding a Read chunk, the tail iovec contains an
		* XDR pad and may be omitted.
		*/
		if (type == rpcrdma_readch && xprt_rdma_pad_optimize)
		return n;

		/* When encoding the Write list, some servers need to see an extra
		@@ -238,10 +240,6 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
		return n;

		if (xdrbuf->tail[0].iov_len) {
		/* the rpcrdma protocol allows us to omit any trailing
		* xdr pad bytes, saving the server an RDMA operation. */
		if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize)
		return n;
		n = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, n);
		if (n == RPCRDMA_MAX_SEGS)
		goto out_overflow;