NFSv4: Allow user to set the port used by the NFSv4 callback channel

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/sysctl.c

@@ -0,0 +1,74 @@
+/*
+ * linux/fs/nfs/sysctl.c
+ *
+ * Sysctl interface to NFS parameters
+ */
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/linkage.h>
+#include <linux/ctype.h>
+#include <linux/fs.h>
+#include <linux/sysctl.h>
+#include <linux/module.h>
+#include <linux/nfs4.h>
+
+#include "callback.h"
+
+static const int nfs_set_port_min = 0;
+static const int nfs_set_port_max = 65535;
+static struct ctl_table_header *nfs_callback_sysctl_table;
+/*
+ * Something that isn't CTL_ANY, CTL_NONE or a value that may clash.
+ * Use the same values as fs/lockd/svc.c
+ */
+#define CTL_UNNUMBERED -2
+
+static ctl_table nfs_cb_sysctls[] = {
+#ifdef CONFIG_NFS_V4
+	{
+		.ctl_name = CTL_UNNUMBERED,
+		.procname = "nfs_callback_tcpport",
+		.data = &nfs_callback_set_tcpport,
+		.maxlen = sizeof(int),
+		.mode = 0644,
+		.proc_handler = &proc_dointvec_minmax,
+		.extra1 = (int *)&nfs_set_port_min,
+		.extra2 = (int *)&nfs_set_port_max,
+	},
+#endif
+	{ .ctl_name = 0 }
+};
+
+static ctl_table nfs_cb_sysctl_dir[] = {
+	{
+		.ctl_name = CTL_UNNUMBERED,
+		.procname = "nfs",
+		.mode = 0555,
+		.child = nfs_cb_sysctls,
+	},
+	{ .ctl_name = 0 }
+};
+
+static ctl_table nfs_cb_sysctl_root[] = {
+	{
+		.ctl_name = CTL_FS,
+		.procname = "fs",
+		.mode = 0555,
+		.child = nfs_cb_sysctl_dir,
+	},
+	{ .ctl_name = 0 }
+};
+
+int nfs_register_sysctl(void)
+{
+	nfs_callback_sysctl_table = register_sysctl_table(nfs_cb_sysctl_root, 0);
+	if (nfs_callback_sysctl_table == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void nfs_unregister_sysctl(void)
+{
+	unregister_sysctl_table(nfs_callback_sysctl_table);
+	nfs_callback_sysctl_table = NULL;
+}