[Ocfs2-devel] 答复: Patch request reviews, for node reconnecting with other nodes whose node number is little than local, thanks a lot.

[Guozhonghua]

Yeah, It is better not disconnect  the TCP source channel than reconnecting.

During the time between disconnection and reconnection, the dlm may be blocked, and the nodes may hangs with each other, waiting for dlms.

Is it correct as the change below?  Disabling the shutdown of the TCP.

static void o2net_idle_timer(unsigned long data)
{
        …………………………………….
        printk(KERN_NOTICE "o2net: Connection to " SC_NODEF_FMT " has been "
               "idle for %lu.%lu secs, shutting it down.\n", SC_NODEF_ARGS(sc),
               msecs / 1000, msecs % 1000);
        /* o2net_sc_queue_work(sc, &sc->sc_shutdown_work); */
}

Thanks a lot.


发件人: Sunil Mushran [mailto:sunil.mushran at gmail.com]
发送时间: 2013年5月10日 1:23
收件人: guozhonghua 02084
抄送: ocfs2-devel at oss.oracle.com; changlimin 00148
主题: Re: [Ocfs2-devel] Patch request reviews, for node reconnecting with other nodes whose node number is little than local, thanks a lot.

Resending as my reply bounced.
On Thu, May 9, 2013 at 10:01 AM, Sunil Mushran <sunil.mushran at gmail.com<mailto:sunil.mushran at gmail.com>> wrote:
A better fix is to _not_ disconnect on o2net timeout once a connection has been
cleanly established. Only disconnect on o2hb timeout.
The reconnects are a problem as we could lose packets and not be aware of it
leading to o2dlm hangs.
IOW, this patch looks to be papering over one specific problem and does not fix the
underlying issue.


On Tue, May 7, 2013 at 7:43 PM, Guozhonghua <guozhonghua at h3c.com<mailto:guozhonghua at h3c.com>> wrote:

Hi, everyone,
I had have a test with eight nodes and find one issue.

The Linux kernel version is 3.2.40.

As I migrate processes from one node to another, those processes is open the files on the OCFS2 storage. Sometime one node shutdown TCP connection with that node whose node number is larger because long time without any message from it.
As the TCP connection shutdown, the node whose number larger did not restart connection to the node, whose number is little and shutdown the TCP connection.
So I review the code of the cluster and find it may be a bug.

I changed it and have a test.

Is there anybody having time to view and make sure that those changes is correct?
Thanks a lot.

The diff file is as below, of the file is /cluster/tcp.c:

root at gzh-dev:/home/dev/test_replace/ocfs2_ko# diff -pu ocfs2-ko-3.2-compare/cluster/tcp.c ocfs2-ko-3.2/cluster/tcp.c
--- ocfs2-ko-3.2-compare/cluster/tcp.c  2012-10-29 19:33:19.534200000 +0800
+++ ocfs2-ko-3.2/cluster/tcp.c        2013-05-08 09:33:16.386277310 +0800
@@ -1699,6 +1698,10 @@ static void o2net_start_connect(struct w
      if (ret == -EINPROGRESS)
              ret = 0;
+      /** Reset the timeout with 0 to avoid connection again */
+      if (ret == 0) {
+              atomic_set(&nn->nn_timeout, 0);
+      }
out:
      if (ret) {
              printk(KERN_NOTICE "o2net: Connect attempt to " SC_NODEF_FMT
@@ -1725,6 +1728,11 @@ static void o2net_connect_expired(struct
       spin_lock(&nn->nn_lock);
      if (!nn->nn_sc_valid) {
+              /** trigger reconnect with other nodes whose node number is little than local
+              *  while they are still able to access the storage
+              */
+              atomic_set(&nn->nn_timeout, 1);
+
               printk(KERN_NOTICE "o2net: No connection established with "
                     "node %u after %u.%u seconds, giving up.\n",
                   o2net_num_from_nn(nn),

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