[Ocfs2-devel] [patch 3/5] ocfs2/dlm: disable BUG_ON when DLM_LOCK_RES_DROPPING_REF is cleared before dlm_deref_lockres_done_handler

[Mark Fasheh]

On Thu, Jul 28, 2016 at 02:06:02PM -0700, Andrew Morton wrote:
> From: piaojun <piaojun at huawei.com>
> Subject: ocfs2/dlm: disable BUG_ON when DLM_LOCK_RES_DROPPING_REF is cleared before dlm_deref_lockres_done_handler
> 
> We found a BUG situation in which DLM_LOCK_RES_DROPPING_REF is cleared
> unexpected that described below.  To solve the bug, we disable the BUG_ON
> and purge lockres in dlm_do_local_recovery_cleanup.
> 
> Node 1                               Node 2(master)
> dlm_purge_lockres
>                                      dlm_deref_lockres_handler
> 
>                                      DLM_LOCK_RES_SETREF_INPROG is set
>                                      response DLM_DEREF_RESPONSE_INPROG
> 
> receive DLM_DEREF_RESPONSE_INPROG
> stop puring in dlm_purge_lockres
> and wait for DLM_DEREF_RESPONSE_DONE
> 
>                                      dispatch dlm_deref_lockres_worker
>                                      response DLM_DEREF_RESPONSE_DONE
> 
> receive DLM_DEREF_RESPONSE_DONE and
> prepare to purge lockres
> 
>                                      Node 2 goes down
> 
> find Node2 down and do local
> clean up for Node2:
> dlm_do_local_recovery_cleanup
>   -> clear DLM_LOCK_RES_DROPPING_REF
> 
> when purging lockres, BUG_ON happens
> because DLM_LOCK_RES_DROPPING_REF is clear:
> dlm_deref_lockres_done_handler
>   ->BUG_ON(!(res->state & DLM_LOCK_RES_DROPPING_REF));

Thanks Piaojun,

Reviewed-by: Mark Fasheh <mfasheh at suse.de>
	--Mark

--
Mark Fasheh