NFSv4: We must set NFS_OPEN_STATE flag in nfs_resync_open_stateid_locked

Otherwise, nfs4_select_rw_stateid() will always return the zero stateid
instead of the correct open stateid.

Fixes: f95549c ("NFSv4: More CLOSE/OPEN races")
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4proc.c

@@ -1200,12 +1200,15 @@ static bool nfs_need_update_open_stateid(struct nfs4_state *state,
 
 static void nfs_resync_open_stateid_locked(struct nfs4_state *state)
 {
+	if (!(state->n_wronly || state->n_rdonly || state->n_rdwr))
+		return;
 	if (state->n_wronly)
 		set_bit(NFS_O_WRONLY_STATE, &state->flags);
 	if (state->n_rdonly)
 		set_bit(NFS_O_RDONLY_STATE, &state->flags);
 	if (state->n_rdwr)
 		set_bit(NFS_O_RDWR_STATE, &state->flags);
+	set_bit(NFS_OPEN_STATE, &state->flags);
 }
 
 static void nfs_clear_open_stateid_locked(struct nfs4_state *state,