diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
new file mode 100644
index 0000000..560d617
--- /dev/null
+++ b/fs/nfs/callback.c
@@ -0,0 +1,187 @@
+/*
+ * linux/fs/nfs/callback.c
+ *
+ * Copyright (C) 2004 Trond Myklebust
+ *
+ * NFSv4 callback handling
+ */
+
+#include <linux/config.h>
+#include <linux/completion.h>
+#include <linux/ip.h>
+#include <linux/module.h>
+#include <linux/smp_lock.h>
+#include <linux/sunrpc/svc.h>
+#include <linux/sunrpc/svcsock.h>
+#include <linux/nfs_fs.h>
+#include "callback.h"
+
+#define NFSDBG_FACILITY NFSDBG_CALLBACK
+
+struct nfs_callback_data {
+	unsigned int users;
+	struct svc_serv *serv;
+	pid_t pid;
+	struct completion started;
+	struct completion stopped;
+};
+
+static struct nfs_callback_data nfs_callback_info;
+static DECLARE_MUTEX(nfs_callback_sema);
+static struct svc_program nfs4_callback_program;
+
+unsigned short nfs_callback_tcpport;
+
+/*
+ * This is the callback kernel thread.
+ */
+static void nfs_callback_svc(struct svc_rqst *rqstp)
+{
+	struct svc_serv *serv = rqstp->rq_server;
+	int err;
+
+	__module_get(THIS_MODULE);
+	lock_kernel();
+
+	nfs_callback_info.pid = current->pid;
+	daemonize("nfsv4-svc");
+	/* Process request with signals blocked, but allow SIGKILL.  */
+	allow_signal(SIGKILL);
+
+	complete(&nfs_callback_info.started);
+
+	while (nfs_callback_info.users != 0 || !signalled()) {
+		/*
+		 * Listen for a request on the socket
+		 */
+		err = svc_recv(serv, rqstp, MAX_SCHEDULE_TIMEOUT);
+		if (err == -EAGAIN || err == -EINTR)
+			continue;
+		if (err < 0) {
+			printk(KERN_WARNING
+					"%s: terminating on error %d\n",
+					__FUNCTION__, -err);
+			break;
+		}
+		dprintk("%s: request from %u.%u.%u.%u\n", __FUNCTION__,
+				NIPQUAD(rqstp->rq_addr.sin_addr.s_addr));
+		svc_process(serv, rqstp);
+	}
+
+	nfs_callback_info.pid = 0;
+	complete(&nfs_callback_info.stopped);
+	unlock_kernel();
+	module_put_and_exit(0);
+}
+
+/*
+ * Bring up the server process if it is not already up.
+ */
+int nfs_callback_up(void)
+{
+	struct svc_serv *serv;
+	struct svc_sock *svsk;
+	int ret = 0;
+
+	lock_kernel();
+	down(&nfs_callback_sema);
+	if (nfs_callback_info.users++ || nfs_callback_info.pid != 0)
+		goto out;
+	init_completion(&nfs_callback_info.started);
+	init_completion(&nfs_callback_info.stopped);
+	serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE);
+	ret = -ENOMEM;
+	if (!serv)
+		goto out_err;
+	/* FIXME: We don't want to register this socket with the portmapper */
+	ret = svc_makesock(serv, IPPROTO_TCP, 0);
+	if (ret < 0)
+		goto out_destroy;
+	if (!list_empty(&serv->sv_permsocks)) {
+		svsk = list_entry(serv->sv_permsocks.next,
+				struct svc_sock, sk_list);
+		nfs_callback_tcpport = ntohs(inet_sk(svsk->sk_sk)->sport);
+		dprintk ("Callback port = 0x%x\n", nfs_callback_tcpport);
+	} else
+		BUG();
+	ret = svc_create_thread(nfs_callback_svc, serv);
+	if (ret < 0)
+		goto out_destroy;
+	nfs_callback_info.serv = serv;
+	wait_for_completion(&nfs_callback_info.started);
+out:
+	up(&nfs_callback_sema);
+	unlock_kernel();
+	return ret;
+out_destroy:
+	svc_destroy(serv);
+out_err:
+	nfs_callback_info.users--;
+	goto out;
+}
+
+/*
+ * Kill the server process if it is not already up.
+ */
+int nfs_callback_down(void)
+{
+	int ret = 0;
+
+	lock_kernel();
+	down(&nfs_callback_sema);
+	if (--nfs_callback_info.users || nfs_callback_info.pid == 0)
+		goto out;
+	kill_proc(nfs_callback_info.pid, SIGKILL, 1);
+	wait_for_completion(&nfs_callback_info.stopped);
+out:
+	up(&nfs_callback_sema);
+	unlock_kernel();
+	return ret;
+}
+
+static int nfs_callback_authenticate(struct svc_rqst *rqstp)
+{
+	struct in_addr *addr = &rqstp->rq_addr.sin_addr;
+	struct nfs4_client *clp;
+
+	/* Don't talk to strangers */
+	clp = nfs4_find_client(addr);
+	if (clp == NULL)
+		return SVC_DROP;
+	dprintk("%s: %u.%u.%u.%u NFSv4 callback!\n", __FUNCTION__, NIPQUAD(addr));
+	nfs4_put_client(clp);
+	switch (rqstp->rq_authop->flavour) {
+		case RPC_AUTH_NULL:
+			if (rqstp->rq_proc != CB_NULL)
+				return SVC_DENIED;
+			break;
+		case RPC_AUTH_UNIX:
+			break;
+		case RPC_AUTH_GSS:
+			/* FIXME: RPCSEC_GSS handling? */
+		default:
+			return SVC_DENIED;
+	}
+	return SVC_OK;
+}
+
+/*
+ * Define NFS4 callback program
+ */
+extern struct svc_version nfs4_callback_version1;
+
+static struct svc_version *nfs4_callback_version[] = {
+	[1] = &nfs4_callback_version1,
+};
+
+static struct svc_stat nfs4_callback_stats;
+
+static struct svc_program nfs4_callback_program = {
+	.pg_prog = NFS4_CALLBACK,			/* RPC service number */
+	.pg_nvers = ARRAY_SIZE(nfs4_callback_version),	/* Number of entries */
+	.pg_vers = nfs4_callback_version,		/* version table */
+	.pg_name = "NFSv4 callback",			/* service name */
+	.pg_class = "nfs",				/* authentication class */
+	.pg_stats = &nfs4_callback_stats,
+	.pg_authenticate = nfs_callback_authenticate,
+};