xprtrdma: Disable pad optimization by default

commit c95a3c6b88658bcb8f77f85f31a0b9d9036e8016 upstream.

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")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index ed5e285fd2ea7f6f26bf08d2d1e8d28db7823f63..fa324fe7394669dded8565aa1368002f79abf8f8 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 39f9e31008bccc1d0592610c312abb529ae57d0f..4d5d5b1c98c446face1bc9be90ea0239b81e32e6 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);
        }