This is a note to let you know that I've just added the patch titled xprtrdma: Disable pad optimization by default to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xprtrdma-disable-pad-optimization-by-default.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From c95a3c6b88658bcb8f77f85f31a0b9d9036e8016 Mon Sep 17 00:00:00 2001 From: Chuck Lever <chuck.lever@xxxxxxxxxx> Date: Wed, 8 Feb 2017 17:00:02 -0500 Subject: xprtrdma: Disable pad optimization by default From: Chuck Lever <chuck.lever@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/sunrpc/xprtrdma/transport.c | 2 +- net/sunrpc/xprtrdma/verbs.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -67,7 +67,7 @@ unsigned int xprt_rdma_max_inline_read = 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) --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -216,6 +216,7 @@ rpcrdma_update_connect_private(struct rp 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); } Patches currently in stable-queue which might be from chuck.lever@xxxxxxxxxx are queue-4.9/xprtrdma-disable-pad-optimization-by-default.patch queue-4.9/xprtrdma-fix-read-chunk-padding.patch queue-4.9/xprtrdma-reduce-required-number-of-send-sges.patch queue-4.9/nfsd-special-case-truncates-some-more.patch queue-4.9/xprtrdma-per-connection-pad-optimization.patch