[Ocfs2-devel] [patch 4/8] ocfs2/dlm: do not purge lockres that is queued for assert master

[Mark Fasheh]

On Mon, Jun 09, 2014 at 01:04:03PM -0700, Andrew Morton wrote:
> @@ -683,6 +684,43 @@ void dlm_lockres_drop_inflight_ref(struc
>  	wake_up(&res->wq);
>  }
>  
> +void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
> +		struct dlm_lock_resource *res)
> +{
> +	assert_spin_locked(&res->spinlock);
> +	res->inflight_assert_workers++;
> +	mlog(0, "%s:%.*s: inflight assert worker++: now %u\n",
> +			dlm->name, res->lockname.len, res->lockname.name,
> +			res->inflight_assert_workers);
> +}
> +
> +void dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
> +		struct dlm_lock_resource *res)
> +{
> +	spin_lock(&res->spinlock);
> +	__dlm_lockres_grab_inflight_worker(dlm, res);
> +	spin_unlock(&res->spinlock);
> +}
> +
> +void __dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
> +		struct dlm_lock_resource *res)
> +{
> +	assert_spin_locked(&res->spinlock);
> +	BUG_ON(res->inflight_assert_workers == 0);
> +	res->inflight_assert_workers--;
> +	mlog(0, "%s:%.*s: inflight assert worker--: now %u\n",
> +			dlm->name, res->lockname.len, res->lockname.name,
> +			res->inflight_assert_workers);
> +}
> +
> +void dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
> +		struct dlm_lock_resource *res)
> +{
> +	spin_lock(&res->spinlock);
> +	__dlm_lockres_drop_inflight_worker(dlm, res);
> +	spin_unlock(&res->spinlock);
> +}
> +
>  /*
>   * lookup a lock resource by name.
>   * may already exist in the hashtable.
> @@ -1603,7 +1641,8 @@ send_response:
>  			mlog(ML_ERROR, "failed to dispatch assert master work\n");
>  			response = DLM_MASTER_RESP_ERROR;
>  			dlm_lockres_put(res);
> -		}
> +		} else
> +			dlm_lockres_grab_inflight_worker(dlm, res);
>  	} else {
>  		if (res)
>  			dlm_lockres_put(res);
> @@ -2118,6 +2157,8 @@ static void dlm_assert_master_worker(str
>  	dlm_lockres_release_ast(dlm, res);
>  
>  put:
> +	dlm_lockres_drop_inflight_worker(dlm, res);
> +
>  	dlm_lockres_put(res);
>  
>  	mlog(0, "finished with dlm_assert_master_worker\n");
> diff -puN fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-do-not-purge-lockres-that-is-queued-for-assert-master fs/ocfs2/dlm/dlmrecovery.c
> --- a/fs/ocfs2/dlm/dlmrecovery.c~ocfs2-dlm-do-not-purge-lockres-that-is-queued-for-assert-master
> +++ a/fs/ocfs2/dlm/dlmrecovery.c
> @@ -1708,7 +1708,8 @@ int dlm_master_requery_handler(struct o2
>  				mlog_errno(-ENOMEM);
>  				/* retry!? */
>  				BUG();
> -			}
> +			} else
> +				__dlm_lockres_grab_inflight_worker(dlm, res);
>  		} else /* put.. incase we are not the master */
>  			dlm_lockres_put(res);
>  		spin_unlock(&res->spinlock);
> diff -puN fs/ocfs2/dlm/dlmthread.c~ocfs2-dlm-do-not-purge-lockres-that-is-queued-for-assert-master fs/ocfs2/dlm/dlmthread.c
> --- a/fs/ocfs2/dlm/dlmthread.c~ocfs2-dlm-do-not-purge-lockres-that-is-queued-for-assert-master
> +++ a/fs/ocfs2/dlm/dlmthread.c
> @@ -259,11 +259,14 @@ static void dlm_run_purge_list(struct dl
>  		 * refs on it. */
>  		unused = __dlm_lockres_unused(lockres);
>  		if (!unused ||
> -		    (lockres->state & DLM_LOCK_RES_MIGRATING)) {
> +		    (lockres->state & DLM_LOCK_RES_MIGRATING) ||
> +		    (lockres->inflight_assert_workers != 0)) {

If there's any assert master message we will halt purging *all* lock
resources. That seems extreme to me :/

What about putting a flag on lockres->state to indicate that it's got some
work queued? We would set it before queuing the work, then clear it in the
worker, or if we ever cancel the work.
	--Mark

--
Mark Fasheh