nfs: allow the v4.1 callback thread to freeze

The v4.1 callback thread has set_freezable() at the top, but it doesn't
ever try to freeze within the loop. Have it call try_to_freeze() at the
top of the loop. If a freeze event occurs, recheck kthread_should_stop()
after thawing.

Reported-by: Yanchuan Nian <ycnian@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 5088b57b078a..cff089a412c7 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -125,6 +125,9 @@ nfs41_callback_svc(void *vrqstp)
         set_freezable();
 
         while (!kthread_should_stop()) {
+                if (try_to_freeze())
+                        continue;
+
                 prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
                 spin_lock_bh(&serv->sv_cb_lock);
                 if (!list_empty(&serv->sv_cb_list)) {