NFS: Add version registering framework
This patch adds in the code to track multiple versions of the NFS
protocol. I created default structures for v2, v3 and v4 so that each
version can continue to work while I convert them into kernel modules.
I also removed the const parameter from the rpc_version array so that I
can change it at runtime.
Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index 0b96c203..66dd307 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -9,8 +9,8 @@
write.o namespace.o mount_clnt.o \
dns_resolve.o cache_lib.o
nfs-$(CONFIG_ROOT_NFS) += nfsroot.o
-nfs-$(CONFIG_NFS_V2) += proc.o nfs2xdr.o
-nfs-$(CONFIG_NFS_V3) += nfs3proc.o nfs3xdr.o
+nfs-$(CONFIG_NFS_V2) += nfs2super.o proc.o nfs2xdr.o
+nfs-$(CONFIG_NFS_V3) += nfs3super.o nfs3proc.o nfs3xdr.o
nfs-$(CONFIG_NFS_V3_ACL) += nfs3acl.o
nfs-$(CONFIG_NFS_V4) += nfs4proc.o nfs4xdr.o nfs4state.o nfs4renewd.o \
nfs4super.o nfs4file.o delegation.o idmap.o \
diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 65afa38..462de24 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -51,25 +51,23 @@
#include "internal.h"
#include "fscache.h"
#include "pnfs.h"
+#include "nfs.h"
#include "netns.h"
#define NFSDBG_FACILITY NFSDBG_CLIENT
static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);
+static DEFINE_SPINLOCK(nfs_version_lock);
+static DEFINE_MUTEX(nfs_version_mutex);
+static LIST_HEAD(nfs_versions);
/*
* RPC cruft for NFS
*/
static const struct rpc_version *nfs_version[5] = {
-#ifdef CONFIG_NFS_V2
- [2] = &nfs_version2,
-#endif
-#ifdef CONFIG_NFS_V3
- [3] = &nfs_version3,
-#endif
-#ifdef CONFIG_NFS_V4
- [4] = &nfs_version4,
-#endif
+ [2] = NULL,
+ [3] = NULL,
+ [4] = NULL,
};
const struct rpc_program nfs_program = {
@@ -101,6 +99,93 @@
};
#endif /* CONFIG_NFS_V3_ACL */
+static struct nfs_subversion *find_nfs_version(unsigned int version)
+{
+ struct nfs_subversion *nfs;
+ spin_lock(&nfs_version_lock);
+
+ list_for_each_entry(nfs, &nfs_versions, list) {
+ if (nfs->rpc_ops->version == version) {
+ spin_unlock(&nfs_version_lock);
+ return nfs;
+ }
+ };
+
+ spin_unlock(&nfs_version_lock);
+ return ERR_PTR(-EPROTONOSUPPORT);;
+}
+
+struct nfs_subversion *get_nfs_version(unsigned int version)
+{
+ struct nfs_subversion *nfs = find_nfs_version(version);
+
+ if (IS_ERR(nfs)) {
+ mutex_lock(&nfs_version_mutex);
+ request_module("nfs%d", version);
+ nfs = find_nfs_version(version);
+ mutex_unlock(&nfs_version_mutex);
+ }
+
+ if (!IS_ERR(nfs))
+ try_module_get(nfs->owner);
+ return nfs;
+}
+
+void put_nfs_version(struct nfs_subversion *nfs)
+{
+ module_put(nfs->owner);
+}
+
+void register_nfs_version(struct nfs_subversion *nfs)
+{
+ spin_lock(&nfs_version_lock);
+
+ list_add(&nfs->list, &nfs_versions);
+ nfs_version[nfs->rpc_ops->version] = nfs->rpc_vers;
+
+ spin_unlock(&nfs_version_lock);
+}
+EXPORT_SYMBOL_GPL(register_nfs_version);
+
+void unregister_nfs_version(struct nfs_subversion *nfs)
+{
+ spin_lock(&nfs_version_lock);
+
+ nfs_version[nfs->rpc_ops->version] = NULL;
+ list_del(&nfs->list);
+
+ spin_unlock(&nfs_version_lock);
+}
+EXPORT_SYMBOL_GPL(unregister_nfs_version);
+
+/*
+ * Preload all configured NFS versions during module init.
+ * This function should be edited after each protocol is converted,
+ * and eventually removed.
+ */
+int __init nfs_register_versions(void)
+{
+ int err = init_nfs_v2();
+ if (err)
+ return err;
+
+ err = init_nfs_v3();
+ if (err)
+ return err;
+
+ return init_nfs_v4();
+}
+
+/*
+ * Remove each pre-loaded NFS version
+ */
+void nfs_unregister_versions(void)
+{
+ exit_nfs_v2();
+ exit_nfs_v3();
+ exit_nfs_v4();
+}
+
/*
* Allocate a shared client record
*
@@ -116,7 +201,10 @@
if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
goto error_0;
- clp->rpc_ops = cl_init->rpc_ops;
+ clp->cl_nfs_mod = cl_init->nfs_mod;
+ try_module_get(clp->cl_nfs_mod->owner);
+
+ clp->rpc_ops = clp->cl_nfs_mod->rpc_ops;
atomic_set(&clp->cl_count, 1);
clp->cl_cons_state = NFS_CS_INITING;
@@ -145,6 +233,7 @@
return clp;
error_cleanup:
+ put_nfs_version(clp->cl_nfs_mod);
kfree(clp);
error_0:
return ERR_PTR(err);
@@ -205,6 +294,7 @@
put_rpccred(clp->cl_machine_cred);
put_net(clp->cl_net);
+ put_nfs_version(clp->cl_nfs_mod);
kfree(clp->cl_hostname);
kfree(clp);
@@ -362,7 +452,7 @@
continue;
/* Different NFS versions cannot share the same nfs_client */
- if (clp->rpc_ops != data->rpc_ops)
+ if (clp->rpc_ops != data->nfs_mod->rpc_ops)
continue;
if (clp->cl_proto != data->proto)
@@ -431,9 +521,10 @@
{
struct nfs_client *clp, *new = NULL;
struct nfs_net *nn = net_generic(cl_init->net, nfs_net_id);
+ const struct nfs_rpc_ops *rpc_ops = cl_init->nfs_mod->rpc_ops;
dprintk("--> nfs_get_client(%s,v%u)\n",
- cl_init->hostname ?: "", cl_init->rpc_ops->version);
+ cl_init->hostname ?: "", rpc_ops->version);
/* see if the client already exists */
do {
@@ -450,14 +541,13 @@
list_add(&new->cl_share_link, &nn->nfs_client_list);
spin_unlock(&nn->nfs_client_lock);
new->cl_flags = cl_init->init_flags;
- return cl_init->rpc_ops->init_client(new,
- timeparms, ip_addr,
- authflavour);
+ return rpc_ops->init_client(new, timeparms, ip_addr,
+ authflavour);
}
spin_unlock(&nn->nfs_client_lock);
- new = cl_init->rpc_ops->alloc_client(cl_init);
+ new = rpc_ops->alloc_client(cl_init);
} while (!IS_ERR(new));
dprintk("<-- nfs_get_client() Failed to find %s (%ld)\n",
@@ -714,13 +804,14 @@
* Create a version 2 or 3 client
*/
static int nfs_init_server(struct nfs_server *server,
- const struct nfs_parsed_mount_data *data)
+ const struct nfs_parsed_mount_data *data,
+ struct nfs_subversion *nfs_mod)
{
struct nfs_client_initdata cl_init = {
.hostname = data->nfs_server.hostname,
.addr = (const struct sockaddr *)&data->nfs_server.address,
.addrlen = data->nfs_server.addrlen,
- .rpc_ops = NULL,
+ .nfs_mod = nfs_mod,
.proto = data->nfs_server.protocol,
.net = data->net,
};
@@ -730,21 +821,6 @@
dprintk("--> nfs_init_server()\n");
- switch (data->version) {
-#ifdef CONFIG_NFS_V2
- case 2:
- cl_init.rpc_ops = &nfs_v2_clientops;
- break;
-#endif
-#ifdef CONFIG_NFS_V3
- case 3:
- cl_init.rpc_ops = &nfs_v3_clientops;
- break;
-#endif
- default:
- return -EPROTONOSUPPORT;
- }
-
nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
data->timeo, data->retrans);
if (data->flags & NFS_MOUNT_NORESVPORT)
@@ -1033,7 +1109,8 @@
* - keyed on server and FSID
*/
struct nfs_server *nfs_create_server(const struct nfs_parsed_mount_data *data,
- struct nfs_fh *mntfh)
+ struct nfs_fh *mntfh,
+ struct nfs_subversion *nfs_mod)
{
struct nfs_server *server;
struct nfs_fattr *fattr;
@@ -1049,7 +1126,7 @@
goto error;
/* Get a client representation */
- error = nfs_init_server(server, data);
+ error = nfs_init_server(server, data, nfs_mod);
if (error < 0)
goto error;
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 35f7e4b..e8877c8 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -50,6 +50,7 @@
#include "fscache.h"
#include "dns_resolve.h"
#include "pnfs.h"
+#include "nfs.h"
#include "netns.h"
#define NFSDBG_FACILITY NFSDBG_VFS
@@ -1671,21 +1672,17 @@
rpc_proc_register(&init_net, &nfs_rpcstat);
#endif
-#ifdef CONFIG_NFS_V4
- err = init_nfs_v4();
+ err = nfs_register_versions();
if (err)
goto out1;
-#endif
if ((err = register_nfs_fs()) != 0)
goto out0;
return 0;
out0:
-#ifdef CONFIG_NFS_V4
- exit_nfs_v4();
+ nfs_unregister_versions();
out1:
-#endif
#ifdef CONFIG_PROC_FS
rpc_proc_unregister(&init_net, "nfs");
#endif
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index cfafd13..ac93647 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -90,7 +90,7 @@
const char *hostname;
const struct sockaddr *addr;
size_t addrlen;
- const struct nfs_rpc_ops *rpc_ops;
+ struct nfs_subversion *nfs_mod;
int proto;
u32 minorversion;
struct net *net;
@@ -189,7 +189,8 @@
struct nfs4_sessionid *);
extern struct nfs_server *nfs_create_server(
const struct nfs_parsed_mount_data *,
- struct nfs_fh *);
+ struct nfs_fh *,
+ struct nfs_subversion *);
extern struct nfs_server *nfs4_create_server(
const struct nfs_parsed_mount_data *,
struct nfs_fh *);
@@ -321,6 +322,7 @@
extern int nfs_wait_bit_killable(void *word);
/* super.c */
+extern struct file_system_type nfs_fs_type;
extern struct file_system_type nfs_xdev_fs_type;
#ifdef CONFIG_NFS_V4
extern struct file_system_type nfs4_xdev_fs_type;
@@ -329,8 +331,8 @@
void nfs_initialise_sb(struct super_block *);
int nfs_set_sb_security(struct super_block *, struct dentry *, struct nfs_mount_info *);
int nfs_clone_sb_security(struct super_block *, struct dentry *, struct nfs_mount_info *);
-struct dentry *nfs_fs_mount_common(struct file_system_type *, struct nfs_server *,
- int, const char *, struct nfs_mount_info *);
+struct dentry *nfs_fs_mount_common(struct nfs_server *, int, const char *,
+ struct nfs_mount_info *, struct nfs_subversion *);
struct dentry *nfs_fs_mount(struct file_system_type *, int, const char *, void *);
struct dentry * nfs_xdev_mount_common(struct file_system_type *, int,
const char *, struct nfs_mount_info *);
diff --git a/fs/nfs/nfs.h b/fs/nfs/nfs.h
new file mode 100644
index 0000000..ac10b9e
--- /dev/null
+++ b/fs/nfs/nfs.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2012 Netapp, Inc. All rights reserved.
+ *
+ * Function and structures exported by the NFS module
+ * for use by NFS version-specific modules.
+ */
+#ifndef __LINUX_INTERNAL_NFS_H
+#define __LINUX_INTERNAL_NFS_H
+
+#include <linux/fs.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/nfs_xdr.h>
+
+struct nfs_subversion {
+ struct module *owner; /* THIS_MODULE pointer */
+ struct file_system_type *nfs_fs; /* NFS filesystem type */
+ const struct rpc_version *rpc_vers; /* NFS version information */
+ const struct nfs_rpc_ops *rpc_ops; /* NFS operations */
+ struct list_head list; /* List of NFS versions */
+};
+
+int nfs_register_versions(void);
+void nfs_unregister_versions(void);
+
+#ifdef CONFIG_NFS_V2
+int init_nfs_v2(void);
+void exit_nfs_v2(void);
+#else /* CONFIG_NFS_V2 */
+static inline int __init init_nfs_v2(void)
+{
+ return 0;
+}
+
+static inline void exit_nfs_v2(void)
+{
+}
+#endif /* CONFIG_NFS_V2 */
+
+#ifdef CONFIG_NFS_V3
+int init_nfs_v3(void);
+void exit_nfs_v3(void);
+#else /* CONFIG_NFS_V3 */
+static inline int __init init_nfs_v3(void)
+{
+ return 0;
+}
+
+static inline void exit_nfs_v3(void)
+{
+}
+#endif /* CONFIG_NFS_V3 */
+
+#ifdef CONFIG_NFS_V4
+int init_nfs_v4(void);
+void exit_nfs_v4(void);
+#else /* CONFIG_NFS_V4 */
+static inline int __init init_nfs_v4(void)
+{
+ return 0;
+}
+
+static inline void exit_nfs_v4(void)
+{
+}
+#endif /* CONFIG_NFS_V4 */
+
+struct nfs_subversion *get_nfs_version(unsigned int);
+void put_nfs_version(struct nfs_subversion *);
+void register_nfs_version(struct nfs_subversion *);
+void unregister_nfs_version(struct nfs_subversion *);
+
+#endif /* __LINUX_INTERNAL_NFS_H */
diff --git a/fs/nfs/nfs2super.c b/fs/nfs/nfs2super.c
new file mode 100644
index 0000000..cef06d4
--- /dev/null
+++ b/fs/nfs/nfs2super.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2012 Netapp, Inc. All rights reserved.
+ */
+#include <linux/module.h>
+#include <linux/nfs_fs.h>
+#include "internal.h"
+#include "nfs.h"
+
+static struct nfs_subversion nfs_v2 = {
+ .owner = THIS_MODULE,
+ .nfs_fs = &nfs_fs_type,
+ .rpc_vers = &nfs_version2,
+ .rpc_ops = &nfs_v2_clientops,
+};
+
+int __init init_nfs_v2(void)
+{
+ register_nfs_version(&nfs_v2);
+ return 0;
+}
+
+void exit_nfs_v2(void)
+{
+ unregister_nfs_version(&nfs_v2);
+}
diff --git a/fs/nfs/nfs3super.c b/fs/nfs/nfs3super.c
new file mode 100644
index 0000000..f815cf3
--- /dev/null
+++ b/fs/nfs/nfs3super.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2012 Netapp, Inc. All rights reserved.
+ */
+#include <linux/module.h>
+#include <linux/nfs_fs.h>
+#include "internal.h"
+#include "nfs.h"
+
+static struct nfs_subversion nfs_v3 = {
+ .owner = THIS_MODULE,
+ .nfs_fs = &nfs_fs_type,
+ .rpc_vers = &nfs_version3,
+ .rpc_ops = &nfs_v3_clientops,
+};
+
+int __init init_nfs_v3(void)
+{
+ register_nfs_version(&nfs_v3);
+ return 0;
+}
+
+void exit_nfs_v3(void)
+{
+ unregister_nfs_version(&nfs_v3);
+}
diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 5511690..99c2e7e 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -366,6 +366,7 @@
/* nfs4super.c */
struct nfs_mount_info;
+extern struct nfs_subversion nfs_v4;
struct dentry *nfs4_try_mount(int, const char *, struct nfs_mount_info *);
int init_nfs_v4(void);
void exit_nfs_v4(void);
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 1c3f13c..769e798 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -357,7 +357,7 @@
.hostname = hostname,
.addr = addr,
.addrlen = addrlen,
- .rpc_ops = &nfs_v4_clientops,
+ .nfs_mod = &nfs_v4,
.proto = proto,
.minorversion = minorversion,
.net = net,
@@ -411,7 +411,7 @@
struct nfs_client_initdata cl_init = {
.addr = ds_addr,
.addrlen = ds_addrlen,
- .rpc_ops = &nfs_v4_clientops,
+ .nfs_mod = &nfs_v4,
.proto = ds_proto,
.minorversion = mds_clp->cl_minorversion,
.net = mds_clp->cl_net,
diff --git a/fs/nfs/nfs4super.c b/fs/nfs/nfs4super.c
index 59264fb..1f34019 100644
--- a/fs/nfs/nfs4super.c
+++ b/fs/nfs/nfs4super.c
@@ -8,6 +8,7 @@
#include <linux/nfs_fs.h>
#include "internal.h"
#include "nfs4_fs.h"
+#include "nfs.h"
#define NFSDBG_FACILITY NFSDBG_VFS
@@ -75,6 +76,13 @@
.remount_fs = nfs_remount,
};
+struct nfs_subversion nfs_v4 = {
+ .owner = THIS_MODULE,
+ .nfs_fs = &nfs4_fs_type,
+ .rpc_vers = &nfs_version4,
+ .rpc_ops = &nfs_v4_clientops,
+};
+
/*
* Set up an NFS4 superblock
*/
@@ -113,7 +121,7 @@
goto out;
}
- mntroot = nfs_fs_mount_common(fs_type, server, flags, dev_name, mount_info);
+ mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, &nfs_v4);
out:
return mntroot;
@@ -293,7 +301,7 @@
goto out;
}
- mntroot = nfs_fs_mount_common(&nfs4_fs_type, server, flags, dev_name, &mount_info);
+ mntroot = nfs_fs_mount_common(server, flags, dev_name, &mount_info, &nfs_v4);
out:
nfs_free_fhandle(mount_info.mntfh);
return mntroot;
@@ -343,6 +351,7 @@
if (err < 0)
goto out2;
+ register_nfs_version(&nfs_v4);
return 0;
out2:
nfs4_unregister_sysctl();
@@ -354,6 +363,7 @@
void exit_nfs_v4(void)
{
+ unregister_nfs_version(&nfs_v4);
unregister_filesystem(&nfs4_fs_type);
nfs4_unregister_sysctl();
nfs_idmap_quit();
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 95866a8c..61405a7 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -64,6 +64,7 @@
#include "internal.h"
#include "fscache.h"
#include "pnfs.h"
+#include "nfs.h"
#define NFSDBG_FACILITY NFSDBG_VFS
#define NFS_TEXT_DATA 1
@@ -281,7 +282,7 @@
static struct dentry *nfs_xdev_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data);
-static struct file_system_type nfs_fs_type = {
+struct file_system_type nfs_fs_type = {
.owner = THIS_MODULE,
.name = "nfs",
.mount = nfs_fs_mount,
@@ -1650,7 +1651,8 @@
}
static struct dentry *nfs_try_mount(int flags, const char *dev_name,
- struct nfs_mount_info *mount_info)
+ struct nfs_mount_info *mount_info,
+ struct nfs_subversion *nfs_mod)
{
int status;
struct nfs_server *server;
@@ -1662,11 +1664,11 @@
}
/* Get a volume representation */
- server = nfs_create_server(mount_info->parsed, mount_info->mntfh);
+ server = nfs_create_server(mount_info->parsed, mount_info->mntfh, nfs_mod);
if (IS_ERR(server))
return ERR_CAST(server);
- return nfs_fs_mount_common(&nfs_fs_type, server, flags, dev_name, mount_info);
+ return nfs_fs_mount_common(server, flags, dev_name, mount_info, nfs_mod);
}
/*
@@ -2297,10 +2299,10 @@
return 0;
}
-struct dentry *nfs_fs_mount_common(struct file_system_type *fs_type,
- struct nfs_server *server,
+struct dentry *nfs_fs_mount_common(struct nfs_server *server,
int flags, const char *dev_name,
- struct nfs_mount_info *mount_info)
+ struct nfs_mount_info *mount_info,
+ struct nfs_subversion *nfs_mod)
{
struct super_block *s;
struct dentry *mntroot = ERR_PTR(-ENOMEM);
@@ -2319,7 +2321,7 @@
sb_mntdata.mntflags |= MS_SYNCHRONOUS;
/* Get a superblock - note that we may end up sharing one that already exists */
- s = sget(fs_type, compare_super, nfs_set_super, flags, &sb_mntdata);
+ s = sget(nfs_mod->nfs_fs, compare_super, nfs_set_super, flags, &sb_mntdata);
if (IS_ERR(s)) {
mntroot = ERR_CAST(s);
goto out_err_nosb;
@@ -2378,6 +2380,7 @@
.set_security = nfs_set_sb_security,
};
struct dentry *mntroot = ERR_PTR(-ENOMEM);
+ struct nfs_subversion *nfs_mod;
int error;
mount_info.parsed = nfs_alloc_parsed_mount_data();
@@ -2394,12 +2397,20 @@
goto out;
}
+ nfs_mod = get_nfs_version(mount_info.parsed->version);
+ if (IS_ERR(nfs_mod)) {
+ mntroot = ERR_CAST(nfs_mod);
+ goto out;
+ }
+
#ifdef CONFIG_NFS_V4
if (mount_info.parsed->version == 4)
mntroot = nfs4_try_mount(flags, dev_name, &mount_info);
else
#endif /* CONFIG_NFS_V4 */
- mntroot = nfs_try_mount(flags, dev_name, &mount_info);
+ mntroot = nfs_try_mount(flags, dev_name, &mount_info, nfs_mod);
+
+ put_nfs_version(nfs_mod);
out:
nfs_free_parsed_mount_data(mount_info.parsed);
@@ -2440,6 +2451,7 @@
struct nfs_clone_mount *data = mount_info->cloned;
struct nfs_server *server;
struct dentry *mntroot = ERR_PTR(-ENOMEM);
+ struct nfs_subversion *nfs_mod = NFS_SB(data->sb)->nfs_client->cl_nfs_mod;
int error;
dprintk("--> nfs_xdev_mount_common()\n");
@@ -2453,7 +2465,7 @@
goto out_err;
}
- mntroot = nfs_fs_mount_common(fs_type, server, flags, dev_name, mount_info);
+ mntroot = nfs_fs_mount_common(server, flags, dev_name, mount_info, nfs_mod);
dprintk("<-- nfs_xdev_mount_common() = 0\n");
out:
return mntroot;
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 6532765..6039297 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -48,6 +48,7 @@
struct rpc_clnt * cl_rpcclient;
const struct nfs_rpc_ops *rpc_ops; /* NFS protocol vector */
int cl_proto; /* Network transport protocol */
+ struct nfs_subversion * cl_nfs_mod; /* pointer to nfs version module */
u32 cl_minorversion;/* NFSv4 minorversion */
struct rpc_cred *cl_machine_cred;