NFS: hard-code init_net for NFS callback transports

In case of destroying mount namespace on child reaper exit, nsproxy is zeroed
to the point already. So, dereferencing of it is invalid.
This patch hard-code "init_net" for all network namespace references for NFS
callback services. This will be fixed with proper NFS callback
containerization.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 970659d..23ff18f 100644
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -17,7 +17,6 @@
 #include <linux/kthread.h>
 #include <linux/sunrpc/svcauth_gss.h>
 #include <linux/sunrpc/bc_xprt.h>
-#include <linux/nsproxy.h>
 
 #include <net/inet_sock.h>
 
@@ -107,7 +106,7 @@
 {
 	int ret;
 
-	ret = svc_create_xprt(serv, "tcp", xprt->xprt_net, PF_INET,
+	ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET,
 				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 	if (ret <= 0)
 		goto out_err;
@@ -115,7 +114,7 @@
 	dprintk("NFS: Callback listener port = %u (af %u)\n",
 			nfs_callback_tcpport, PF_INET);
 
-	ret = svc_create_xprt(serv, "tcp", xprt->xprt_net, PF_INET6,
+	ret = svc_create_xprt(serv, "tcp", &init_net, PF_INET6,
 				nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
 	if (ret > 0) {
 		nfs_callback_tcpport6 = ret;
@@ -184,7 +183,7 @@
 	 * fore channel connection.
 	 * Returns the input port (0) and sets the svc_serv bc_xprt on success
 	 */
-	ret = svc_create_xprt(serv, "tcp-bc", xprt->xprt_net, PF_INET, 0,
+	ret = svc_create_xprt(serv, "tcp-bc", &init_net, PF_INET, 0,
 			      SVC_SOCK_ANONYMOUS);
 	if (ret < 0) {
 		rqstp = ERR_PTR(ret);
@@ -254,7 +253,7 @@
 	char svc_name[12];
 	int ret = 0;
 	int minorversion_setup;
-	struct net *net = current->nsproxy->net_ns;
+	struct net *net = &init_net;
 
 	mutex_lock(&nfs_callback_mutex);
 	if (cb_info->users++ || cb_info->task != NULL) {
@@ -330,7 +329,7 @@
 	cb_info->users--;
 	if (cb_info->users == 0 && cb_info->task != NULL) {
 		kthread_stop(cb_info->task);
-		svc_shutdown_net(cb_info->serv, current->nsproxy->net_ns);
+		svc_shutdown_net(cb_info->serv, &init_net);
 		svc_exit_thread(cb_info->rqst);
 		cb_info->serv = NULL;
 		cb_info->rqst = NULL;