NFS: cache_lib: use complete() instead of complete_all()

There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

The generic caching code from sunrpc is calling revisit() only once.

The usage pattern of the completion is:

waiter context                          waker context

do_cache_lookup_wait()
  nfs_cache_defer_req_alloc()
    init_completion()
  do_cache_lookup()
  nfs_cache_wait_for_upcall()
    wait_for_completion_timeout()

					nfs_dns_cache_revisit()
					  complete()

  nfs_cache_defer_req_put()
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/cache_lib.c

@@ -76,7 +76,7 @@ static void nfs_dns_cache_revisit(struct cache_deferred_req *d, int toomany)
 
 	dreq = container_of(d, struct nfs_cache_defer_req, deferred_req);
 
-	complete_all(&dreq->completion);
+	complete(&dreq->completion);
 	nfs_cache_defer_req_put(dreq);
 }