xprtrdma: Disable pad optimization by default

Commit d5440e27d3e5 ("xprtrdma: Enable pad optimization") made the
Linux client omit XDR round-up padding in normal Read and Write
chunks so that the client doesn't have to register and invalidate
3-byte memory regions that contain no real data.

Unfortunately, my cheery 2014 assessment that this optimization "is
supported now by both Linux and Solaris servers" was premature.
We've found bugs in Solaris in this area since commit d5440e27d3e5
("xprtrdma: Enable pad optimization") was merged (SYMLINK is the
main offender).

So for maximum interoperability, I'm disabling this optimization
again. If a CM private message is exchanged when connecting, the
client recognizes that the server is Linux, and enables the
optimization for that connection.

Until now the Solaris server bugs did not impact common operations,
and were thus largely benign. Soon, less capable devices on Linux
NFS/RDMA clients will make use of Read chunks more often, and these
Solaris bugs will prevent interoperation in more cases.

Fixes: 677eb17e94ed ("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>

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 534c178d2a7e2e283074c60561099fd7d3444139..699058169cfcd046c00f46b7fe3f883539d341c0 100644 (file)
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -67,7 +67,7 @@ unsigned int xprt_rdma_max_inline_read = RPCRDMA_DEF_INLINE;
 static unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE;
 static unsigned int xprt_rdma_inline_write_padding;
 static unsigned int xprt_rdma_memreg_strategy = RPCRDMA_FRMR;
-               int xprt_rdma_pad_optimize = 1;
+               int xprt_rdma_pad_optimize = 0;
 
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 2a6a367a2dacfa1eb90ba5f9936ffeb2d2a9df2b..23f4da419a648b2d03baf63f6196e3fd71282a0c 100644 (file)
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -216,6 +216,7 @@ rpcrdma_update_connect_private(struct rpcrdma_xprt *r_xprt,
            pmsg->cp_magic == rpcrdma_cmp_magic &&
            pmsg->cp_version == RPCRDMA_CMP_VERSION) {
                r_xprt->rx_ia.ri_reminv_expected = true;
+               r_xprt->rx_ia.ri_implicit_roundup = true;
                rsize = rpcrdma_decode_buffer_size(pmsg->cp_send_size);
                wsize = rpcrdma_decode_buffer_size(pmsg->cp_recv_size);
        }