• Chuck Lever's avatar
    svcrdma: Ignore source port when computing DRC hash · 44b14046
    Chuck Lever authored
    commit 1e091c3bbf51d34d5d96337a59ce5ab2ac3ba2cc upstream.
    
    The DRC appears to be effectively empty after an RPC/RDMA transport
    reconnect. The problem is that each connection uses a different
    source port, which defeats the DRC hash.
    
    Clients always have to disconnect before they send retransmissions
    to reset the connection's credit accounting, thus every retransmit
    on NFS/RDMA will miss the DRC.
    
    An NFS/RDMA client's IP source port is meaningless for RDMA
    transports. The transport layer typically sets the source port value
    on the connection to a random ephemeral port. The server already
    ignores it for the "secure port" check. See commit 16e4d93f
    ("NFSD: Ignore client's source port on RDMA transports").
    
    The Linux NFS server's DRC resolves XID collisions from the same
    source IP address by using the checksum of the first 200 bytes of
    the RPC call header.
    Signed-off-by: 's avatarChuck Lever <chuck.lever@oracle.com>
    Cc: stable@vger.kernel.org # v4.14+
    Signed-off-by: 's avatarJ. Bruce Fields <bfields@redhat.com>
    Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    44b14046
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