Re: [PATCH v2] fs/nfsd/nfs4callback: Remove deprecated create_singlethread_workqueue

[Jeff Layton]

On Wed, 2016-11-09 at 15:23 -0500, J. Bruce Fields wrote:
On Wed, Nov 09, 2016 at 02:47:24PM -0500, J. Bruce Fields wrote:

For now I wish we could just like to continue assuming the workqueue
processes only one item at a time.  Do we have that now, or do we need
to switch to (looking at workqueue.h...) alloc_ordered workqueue()?

Oh, wait, I missed the _ordered_ in:

	#define create_singlethread_workqueue(name) \
	        alloc_ordered_workqueue("%s", __WQ_LEGACY | WQ_MEM_RECLAIM, name)

So our existing create_singlethread_workqueue is fine--but we probably
don't need those flags:

--b.

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 211dc2aed8e1..eb78109d666c 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1061,7 +1061,7 @@ static const struct rpc_call_ops nfsd4_cb_ops = {
 
 int nfsd4_create_callback_queue(void)
 {
-	callback_wq = create_singlethread_workqueue("nfsd4_callbacks");
+	callback_wq = alloc_ordered_workqueue("nfsd4_callbacks", 0);
 	if (!callback_wq)
 		return -ENOMEM;
 	return 0;

That looks good to me. Eventually we could better serialize the handling
of the callback code and move to an unordered workqueue, but for now I
think Bruce is right that we have to keep it.


Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>