[Ocfs2-devel] ocfs2: o2net: fix packets lost issue when reconnect

[Junxiao Bi <junxiao.bi@oracle.com>]

Hi,

This patch serial is to fix a possible message lost bug in ocfs2 when
network go bad. This bug will cause ocfs2 hung forever even network
become good again.
The messages may lost in this case. After the tcp connection is established
between two nodes, an idle timer will be set to check its state periodically,
if no messages are received during this time, idle timer will timeout, it will
shutdown the connection and try to reconnect, so pending messages in tcp queues
will be lost. This messages may be from dlm. Dlm may get hung in this case. This
may cause the whole ocfs2 cluster hung. 
This is very possible to happen when network state goes bad. Do the reconnect is
useless, it will fail if network state is still bad. Just waiting there for
network recovering may be a good idea, it will not lost messages and some node
will be fenced until cluster goes into split-brain state, for this case, Tcp user
timeout is used to override the tcp retransmit timeout. It will timeout after 25
days, user should have notice this through the provided log and fix the network,
if they don't, ocfs2 will fall back to original reconnect way.
This is a resend of the patches, no changes since last time. Please help review.

Thanks,
Junxiao.