/*
   *	fs/nfsctl.c
   *
   *	This should eventually move to userland.
   *
   */

  #include <linux/types.h>

  #include <linux/file.h>
  #include <linux/fs.h>
  #include <linux/sunrpc/svc.h>
  #include <linux/nfsd/nfsd.h>
  #include <linux/nfsd/syscall.h>

  #include <linux/cred.h>
  #include <linux/sched.h>

  #include <linux/linkage.h>
  #include <linux/namei.h>
  #include <linux/mount.h>
  #include <linux/syscalls.h>
  #include <asm/uaccess.h>
  
  /*
   * open a file on nfsd fs
   */
  
  static struct file *do_open(char *name, int flags)
  {
  	struct nameidata nd;

  	struct vfsmount *mnt;

  	int error;

  	mnt = do_kern_mount("nfsd", 0, "nfsd", NULL);
  	if (IS_ERR(mnt))
  		return (struct file *)mnt;

  	error = vfs_path_lookup(mnt->mnt_root, mnt, name, 0, &nd);
  	mntput(mnt);	/* drop do_kern_mount reference */

  	if (error)
  		return ERR_PTR(error);
  
  	if (flags == O_RDWR)

  		error = may_open(&nd.path, MAY_READ|MAY_WRITE,
  					   FMODE_READ|FMODE_WRITE);

  	else

  		error = may_open(&nd.path, MAY_WRITE, FMODE_WRITE);

  
  	if (!error)

  		return dentry_open(nd.path.dentry, nd.path.mnt, flags,
  				   current_cred());

  	path_put(&nd.path);

  	return ERR_PTR(error);
  }
  
  static struct {
  	char *name; int wsize; int rsize;
  } map[] = {
  	[NFSCTL_SVC] = {
  		.name	= ".svc",
  		.wsize	= sizeof(struct nfsctl_svc)
  	},
  	[NFSCTL_ADDCLIENT] = {
  		.name	= ".add",
  		.wsize	= sizeof(struct nfsctl_client)
  	},
  	[NFSCTL_DELCLIENT] = {
  		.name	= ".del",
  		.wsize	= sizeof(struct nfsctl_client)
  	},
  	[NFSCTL_EXPORT] = {
  		.name	= ".export",
  		.wsize	= sizeof(struct nfsctl_export)
  	},
  	[NFSCTL_UNEXPORT] = {
  		.name	= ".unexport",
  		.wsize	= sizeof(struct nfsctl_export)
  	},
  	[NFSCTL_GETFD] = {
  		.name	= ".getfd",
  		.wsize	= sizeof(struct nfsctl_fdparm),
  		.rsize	= NFS_FHSIZE
  	},
  	[NFSCTL_GETFS] = {
  		.name	= ".getfs",
  		.wsize	= sizeof(struct nfsctl_fsparm),
  		.rsize	= sizeof(struct knfsd_fh)
  	},
  };

  SYSCALL_DEFINE3(nfsservctl, int, cmd, struct nfsctl_arg __user *, arg,
  		void __user *, res)

  {
  	struct file *file;
  	void __user *p = &arg->u;
  	int version;
  	int err;
  
  	if (copy_from_user(&version, &arg->ca_version, sizeof(int)))
  		return -EFAULT;

  	if (version != NFSCTL_VERSION)

  		return -EINVAL;

  	if (cmd < 0 || cmd >= ARRAY_SIZE(map) || !map[cmd].name)

  		return -EINVAL;
  
  	file = do_open(map[cmd].name, map[cmd].rsize ? O_RDWR : O_WRONLY);	
  	if (IS_ERR(file))
  		return PTR_ERR(file);
  	err = file->f_op->write(file, p, map[cmd].wsize, &file->f_pos);
  	if (err >= 0 && map[cmd].rsize)
  		err = file->f_op->read(file, res, map[cmd].rsize, &file->f_pos);
  	if (err >= 0)
  		err = 0;
  	fput(file);
  	return err;
  }