src/patches/suse-2.6.27.31/patches.fixes/sunrpc-tcp-reconnect

   1 From: NeilBrown <neilb@suse.de>
   2 Subject: reset TCP connect timeout on successful connection.
   3 Patch-mainline: no - see below
   4 References: bnc#498708
   5
   6 Currently, every time an NFS server closes a TCP connection, the
   7 client will double its time out (up to 300 seconds) before attempting
   8 to reconnect.
   9 The timeout should only double while it fails.  On success it should
  10 reset the timeout.
  11
  12 This patch resets the timeout on a successful connection.
  13 It also ensures that we the timeout it doubled, it does not remain at
  14 0.  This should fix a behaviour which has been observed where the
  15 client hammers on the server until it accepts a connection.
  16
  17 Note: this has not been accepted upstream.
  18 The stated reason is that some (Netapp?) servers are prone to accept
  19 a connection and then drop it immediately.  This would defeat the backoff.
  20 While this should be fixed there are complexities in getting it right,
  21 and the current patch is at least an improvement.
  22 (there where already cases where the client would retry at a high
  23  rate and the new case is, I think, quite remote).
  24 When things are sorted out with upstream, we can get a better fix.
  25
  26 Signed-off-by: NeilBrown <neilb@suse.de>
  27
  28 ---
  29  net/sunrpc/xprtsock.c |    3 +++
  30  1 file changed, 3 insertions(+)
  31
  32 --- a/net/sunrpc/xprtsock.c
  33 +++ b/net/sunrpc/xprtsock.c
  34 @@ -1143,6 +1143,7 @@ static void xs_tcp_state_change(struct s
  35                                 TCP_RCV_COPY_FRAGHDR | TCP_RCV_COPY_XID;
  36
  37                         xprt_wake_pending_tasks(xprt, 0);
  38 +                       xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  39                 }
  40                 spin_unlock_bh(&xprt->transport_lock);
  41                 break;
  42 @@ -1785,6 +1786,8 @@ static void xs_connect(struct rpc_task *
  43                                    &transport->connect_worker,
  44                                    xprt->reestablish_timeout);
  45                 xprt->reestablish_timeout <<= 1;
  46 +               if (xprt->reestablish_timeout < XS_TCP_INIT_REEST_TO)
  47 +                       xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
  48                 if (xprt->reestablish_timeout > XS_TCP_MAX_REEST_TO)
  49                         xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;
  50         } else {