From 24abdf1be15c478e2821d6fc903a4a4440beff02 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Wed, 8 Feb 2017 16:59:46 -0500 Subject: [PATCH] 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 677eb17e94ed ("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: 677eb17e94ed ("xprtrdma: Fix XDR tail buffer marshalling") Cc: stable@vger.kernel.org # v4.9+ Signed-off-by: Chuck Lever Signed-off-by: Anna Schumaker --- net/sunrpc/xprtrdma/rpc_rdma.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c index c52e0f2ffe52..a524d3c2e8ac 100644 --- a/net/sunrpc/xprtrdma/rpc_rdma.c +++ b/net/sunrpc/xprtrdma/rpc_rdma.c @@ -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; -- 2.20.1