nfs: stash nfs_subversion reference into nfs_mount_info

That will allow to get rid of passing those references around in
quite a few places.  Moreover, that will allow to merge xdev and
remote file_system_type.
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/internal.h

@@ -142,6 +142,7 @@ struct nfs_mount_info {
 	struct nfs_clone_mount *cloned;
 	struct nfs_server *server;
 	struct nfs_fh *mntfh;
+	struct nfs_subversion *nfs_mod;
 };
 
 extern int nfs_mount(struct nfs_mount_request *info);

fs/nfs/namespace.c

@@ -236,8 +236,8 @@ struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
 		.set_security = nfs_clone_sb_security,
 		.cloned = &mountdata,
 		.mntfh = fh,
+		.nfs_mod = NFS_SB(sb)->nfs_client->cl_nfs_mod,
 	};
-	struct nfs_subversion *nfs_mod = NFS_SB(sb)->nfs_client->cl_nfs_mod;
 	struct nfs_server *server;
 	struct vfsmount *mnt;
 	char *page = (char *) __get_free_page(GFP_USER);
@@ -246,7 +246,7 @@ struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
 	if (page == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	server = nfs_mod->rpc_ops->clone_server(NFS_SB(sb), fh,
+	server = mount_info.nfs_mod->rpc_ops->clone_server(NFS_SB(sb), fh,
 							   fattr, authflavor);
 	if (IS_ERR(server))
 		return ERR_CAST(server);

fs/nfs/nfs4super.c

@@ -248,6 +248,7 @@ static struct dentry *nfs4_referral_mount(struct file_system_type *fs_type,
 		.fill_super = nfs_fill_super,
 		.set_security = nfs_clone_sb_security,
 		.cloned = data,
+		.nfs_mod = &nfs_v4,
 	};
 	struct dentry *res;
 

fs/nfs/super.c

@@ -2761,6 +2761,7 @@ struct dentry *nfs_fs_mount(struct file_system_type *fs_type,
 		mntroot = ERR_CAST(nfs_mod);
 		goto out;
 	}
+	mount_info.nfs_mod = nfs_mod;
 
 	mntroot = nfs_mod->rpc_ops->try_mount(flags, dev_name, &mount_info, nfs_mod);