fs/afs/rxrpc: Remove deprecated create_singlethread_workqueue

The workqueue "afs_async_calls" queues work item
&call->async_work per afs_call. Since there could be multiple calls and since
these calls can be run concurrently, alloc_workqueue has been used to replace
the deprecated create_singlethread_workqueue instance.

The WQ_MEM_RECLAIM flag has been set to ensure forward progress under
memory pressure because the workqueue is being used on a memory reclaim
path.

Since there are fixed number of work items, explicit concurrency
limit is unnecessary here.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/rxrpc.c

@@ -76,7 +76,7 @@ int afs_open_socket(void)
 	_enter("");
 
 	ret = -ENOMEM;
-	afs_async_calls = create_singlethread_workqueue("kafsd");
+	afs_async_calls = alloc_workqueue("kafsd", WQ_MEM_RECLAIM, 0);
 	if (!afs_async_calls)
 		goto error_0;