NFSD: Fix error return code in nfsd4_interssc_connect()

'status' has been overwritten to 0 after nfsd4_ssc_setup_dul(), this
cause 0 will be return in vfs_kern_mount() error case. Fix to return
nfserr_nodev in this error.

Fixes: f4e44b3 ("NFSD: delay unmount source's export after inter-server copy completed.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -1323,6 +1323,7 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
 	ss_mnt = vfs_kern_mount(type, SB_KERNMOUNT, dev_name, raw_data);
 	module_put(type->owner);
 	if (IS_ERR(ss_mnt)) {
+		status = nfserr_nodev;
 		if (work)
 			nfsd4_ssc_cancel_dul_work(nn, work);
 		goto out_free_devname;