Hi Junxiao, On 2016/1/21 15:34, Junxiao Bi wrote: > Hi Jiufei, > > I didn't find other solution for this issue. You can go with yours. > Looks like your second one is more straightforward, there deref work can > be removed. > There are two problems with the second solution: 1) Node retry to deref the lock resource will block dlm_thread to process other lock resources. 2) When node retries to drop the refmap bit, the master may be in another assert master work, that will take a long time to purge a lockres. So I prefer the first solution.
Thanks, Jiufei > Thanks, > Junxiao. > On 01/11/2016 10:46 AM, xuejiufei wrote: >> Hi all, >> We have found a race between refmap setting and clearing which >> will cause the lock resource on master is freed before other nodes >> purge it. >> >> Node 1 Node 2(master) >> dlm_do_master_request >> dlm_master_request_handler >> -> dlm_lockres_set_refmap_bit >> call dlm_purge_lockres after unlock >> dlm_deref_handler >> -> find lock resource is in >> DLM_LOCK_RES_SETREF_INPROG state, >> so dispatch a deref work >> dlm_purge_lockres succeed. >> >> dlm_do_master_request >> dlm_master_request_handler >> -> dlm_lockres_set_refmap_bit >> >> deref work trigger, call >> dlm_lockres_clear_refmap_bit >> to clear Node 1 from refmap >> >> Now Node 2 can purge the lock resource but the owner of lock resource >> on Node 1 is still Node 2 which may trigger BUG if the lock resource >> is $RECOVERY or other problems. >> >> We have discussed 2 solutions: >> 1)The master return error to Node 1 if the DLM_LOCK_RES_SETREF_INPROG >> is set. Node 1 will not retry and master send another message to Node 1 >> after clearing the refmap. Node 1 can purge the lock resource after the >> refmap on master is cleared. >> 2) The master return error to Node 1 if the DLM_LOCK_RES_SETREF_INPROG >> is set, and Node 1 will retry to deref the lockres. >> >> Does anybody has better ideas? >> >> Thanks, >> --Jiufei >> > > > . > _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel
