NFSv4: Convert struct nfs4_state to use refcount_t

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

fs/nfs/nfs4_fs.h

@@ -188,7 +188,7 @@ struct nfs4_state {
 	unsigned int n_wronly;		/* Number of write-only references */
 	unsigned int n_rdwr;		/* Number of read/write references */
 	fmode_t state;			/* State on the server (R,W, or RW) */
-	atomic_t count;
+	refcount_t count;
 
 	wait_queue_head_t waitq;
 	struct rcu_head rcu_head;