[PATCH] CTDB changes

Amitay Isaacs amitay at gmail.com
Tue Aug 19 21:55:13 MDT 2014

Hi All,

Here are some more CTDB locking changes.  These changes add a TALLOC_CTX to
all the locking calls.  So the requests are correctly created using the
specified TALLOC_CTX and freeing the context will automatically clean up
lock context associated with it.

This patch series also includes a patch to fix one of the long standing
issues of high hopcounts.  In some case, a lock request will keep bouncing
back and forth between two nodes very quickly.  This occurs during a small
window when a record is migrated from one node to other node and the
migrated record has not yet been written to the database.  During this time
the dmaster information on both the nodes is inconsistent and each node
points to the other node as dmaster.  This issue was further complicated by
ctdb lock wait processes getting starved when waiting for robust mutex lock
for the migrated record.  We need to ensure that ctdb lock wait processes
run with higher priority than smbd, so ctdb can finish migration of records
quickly.  Also, hold off all the record requests if there is record
migration in progress.  This will avoid record requests bouncing between
the nodes like crazy.

The patches are in my ctdb-wip branch and are also attached.


Please review and push if ok.

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