// SPDX-License-Identifier: GPL-2.0-only

  /*
   * net/sunrpc/rpc_pipe.c
   *
   * Userland/kernel interface for rpcauth_gss.
   * Code shamelessly plagiarized from fs/nfsd/nfsctl.c

   * and fs/sysfs/inode.c

   *
   * Copyright (c) 2002, Trond Myklebust <trond.myklebust@fys.uio.no>
   *
   */

  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/pagemap.h>
  #include <linux/mount.h>

  #include <linux/fs_context.h>

  #include <linux/namei.h>

  #include <linux/fsnotify.h>

  #include <linux/kernel.h>

  #include <linux/rcupdate.h>

  #include <linux/utsname.h>

  
  #include <asm/ioctls.h>

  #include <linux/poll.h>
  #include <linux/wait.h>
  #include <linux/seq_file.h>
  
  #include <linux/sunrpc/clnt.h>
  #include <linux/workqueue.h>
  #include <linux/sunrpc/rpc_pipe_fs.h>

  #include <linux/sunrpc/cache.h>

  #include <linux/nsproxy.h>

  #include <linux/notifier.h>

  #include "netns.h"

  #include "sunrpc.h"

  #define RPCDBG_FACILITY RPCDBG_DEBUG
  
  #define NET_NAME(net)	((net == &init_net) ? " (init_net)" : "")

  
  static struct file_system_type rpc_pipe_fs_type;

  static const struct rpc_pipe_ops gssd_dummy_pipe_ops;

  static struct kmem_cache *rpc_inode_cachep __read_mostly;

  
  #define RPC_UPCALL_TIMEOUT (30*HZ)

  static BLOCKING_NOTIFIER_HEAD(rpc_pipefs_notifier_list);
  
  int rpc_pipefs_notifier_register(struct notifier_block *nb)
  {

  	return blocking_notifier_chain_register(&rpc_pipefs_notifier_list, nb);

  }
  EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_register);
  
  void rpc_pipefs_notifier_unregister(struct notifier_block *nb)
  {
  	blocking_notifier_chain_unregister(&rpc_pipefs_notifier_list, nb);
  }
  EXPORT_SYMBOL_GPL(rpc_pipefs_notifier_unregister);

  static void rpc_purge_list(wait_queue_head_t *waitq, struct list_head *head,

  		void (*destroy_msg)(struct rpc_pipe_msg *), int err)

  {

  	struct rpc_pipe_msg *msg;

  	if (list_empty(head))
  		return;
  	do {

  		msg = list_entry(head->next, struct rpc_pipe_msg, list);

  		list_del_init(&msg->list);

  		msg->errno = err;

  		destroy_msg(msg);

  	} while (!list_empty(head));

  
  	if (waitq)
  		wake_up(waitq);

  }
  
  static void

  rpc_timeout_upcall_queue(struct work_struct *work)

  {

  	LIST_HEAD(free_list);

  	struct rpc_pipe *pipe =
  		container_of(work, struct rpc_pipe, queue_timeout.work);

  	void (*destroy_msg)(struct rpc_pipe_msg *);

  	struct dentry *dentry;

  	spin_lock(&pipe->lock);

  	destroy_msg = pipe->ops->destroy_msg;
  	if (pipe->nreaders == 0) {
  		list_splice_init(&pipe->pipe, &free_list);
  		pipe->pipelen = 0;

  	}

  	dentry = dget(pipe->dentry);

  	spin_unlock(&pipe->lock);

  	rpc_purge_list(dentry ? &RPC_I(d_inode(dentry))->waitq : NULL,

  			&free_list, destroy_msg, -ETIMEDOUT);
  	dput(dentry);

  }

  ssize_t rpc_pipe_generic_upcall(struct file *filp, struct rpc_pipe_msg *msg,
  				char __user *dst, size_t buflen)
  {
  	char *data = (char *)msg->data + msg->copied;
  	size_t mlen = min(msg->len - msg->copied, buflen);
  	unsigned long left;
  
  	left = copy_to_user(dst, data, mlen);
  	if (left == mlen) {
  		msg->errno = -EFAULT;
  		return -EFAULT;
  	}
  
  	mlen -= left;
  	msg->copied += mlen;
  	msg->errno = 0;
  	return mlen;
  }
  EXPORT_SYMBOL_GPL(rpc_pipe_generic_upcall);

  /**

   * rpc_queue_upcall - queue an upcall message to userspace

   * @pipe: upcall pipe on which to queue given message

   * @msg: message to queue
   *
   * Call with an @inode created by rpc_mkpipe() to queue an upcall.
   * A userspace process may then later read the upcall by performing a
   * read on an open file for this inode.  It is up to the caller to
   * initialize the fields of @msg (other than @msg->list) appropriately.
   */

  int

  rpc_queue_upcall(struct rpc_pipe *pipe, struct rpc_pipe_msg *msg)

  {

  	int res = -EPIPE;

  	struct dentry *dentry;

  	spin_lock(&pipe->lock);

  	if (pipe->nreaders) {
  		list_add_tail(&msg->list, &pipe->pipe);
  		pipe->pipelen += msg->len;

  		res = 0;

  	} else if (pipe->flags & RPC_PIPE_WAIT_FOR_OPEN) {
  		if (list_empty(&pipe->pipe))

  			queue_delayed_work(rpciod_workqueue,

  					&pipe->queue_timeout,

  					RPC_UPCALL_TIMEOUT);

  		list_add_tail(&msg->list, &pipe->pipe);
  		pipe->pipelen += msg->len;

  		res = 0;
  	}

  	dentry = dget(pipe->dentry);

  	spin_unlock(&pipe->lock);

  	if (dentry) {

  		wake_up(&RPC_I(d_inode(dentry))->waitq);

  		dput(dentry);
  	}

  	return res;
  }

  EXPORT_SYMBOL_GPL(rpc_queue_upcall);

  static inline void
  rpc_inode_setowner(struct inode *inode, void *private)
  {
  	RPC_I(inode)->private = private;
  }

  static void
  rpc_close_pipes(struct inode *inode)
  {

  	struct rpc_pipe *pipe = RPC_I(inode)->pipe;

  	int need_release;

  	LIST_HEAD(free_list);

  	inode_lock(inode);

  	spin_lock(&pipe->lock);
  	need_release = pipe->nreaders != 0 || pipe->nwriters != 0;
  	pipe->nreaders = 0;
  	list_splice_init(&pipe->in_upcall, &free_list);
  	list_splice_init(&pipe->pipe, &free_list);
  	pipe->pipelen = 0;
  	pipe->dentry = NULL;
  	spin_unlock(&pipe->lock);

  	rpc_purge_list(&RPC_I(inode)->waitq, &free_list, pipe->ops->destroy_msg, -EPIPE);

  	pipe->nwriters = 0;
  	if (need_release && pipe->ops->release_pipe)
  		pipe->ops->release_pipe(inode);
  	cancel_delayed_work_sync(&pipe->queue_timeout);

  	rpc_inode_setowner(inode, NULL);

  	RPC_I(inode)->pipe = NULL;

  	inode_unlock(inode);

  }

  static struct inode *
  rpc_alloc_inode(struct super_block *sb)
  {
  	struct rpc_inode *rpci;

  	rpci = kmem_cache_alloc(rpc_inode_cachep, GFP_KERNEL);

  	if (!rpci)
  		return NULL;
  	return &rpci->vfs_inode;
  }
  
  static void

  rpc_free_inode(struct inode *inode)

  {
  	kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
  }
  
  static int
  rpc_pipe_open(struct inode *inode, struct file *filp)
  {

  	struct rpc_pipe *pipe;

  	int first_open;

  	int res = -ENXIO;

  	inode_lock(inode);

  	pipe = RPC_I(inode)->pipe;
  	if (pipe == NULL)

  		goto out;

  	first_open = pipe->nreaders == 0 && pipe->nwriters == 0;
  	if (first_open && pipe->ops->open_pipe) {
  		res = pipe->ops->open_pipe(inode);

  		if (res)
  			goto out;

  	}

  	if (filp->f_mode & FMODE_READ)

  		pipe->nreaders++;

  	if (filp->f_mode & FMODE_WRITE)

  		pipe->nwriters++;

  	res = 0;
  out:

  	inode_unlock(inode);

  	return res;
  }
  
  static int
  rpc_pipe_release(struct inode *inode, struct file *filp)
  {

  	struct rpc_pipe *pipe;

  	struct rpc_pipe_msg *msg;

  	int last_close;

  	inode_lock(inode);

  	pipe = RPC_I(inode)->pipe;
  	if (pipe == NULL)

  		goto out;

  	msg = filp->private_data;

  	if (msg != NULL) {

  		spin_lock(&pipe->lock);

  		msg->errno = -EAGAIN;

  		list_del_init(&msg->list);

  		spin_unlock(&pipe->lock);
  		pipe->ops->destroy_msg(msg);

  	}
  	if (filp->f_mode & FMODE_WRITE)

  		pipe->nwriters --;

  	if (filp->f_mode & FMODE_READ) {

  		pipe->nreaders --;
  		if (pipe->nreaders == 0) {

  			LIST_HEAD(free_list);

  			spin_lock(&pipe->lock);
  			list_splice_init(&pipe->pipe, &free_list);
  			pipe->pipelen = 0;
  			spin_unlock(&pipe->lock);

  			rpc_purge_list(&RPC_I(inode)->waitq, &free_list,

  					pipe->ops->destroy_msg, -EAGAIN);

  		}
  	}

  	last_close = pipe->nwriters == 0 && pipe->nreaders == 0;
  	if (last_close && pipe->ops->release_pipe)
  		pipe->ops->release_pipe(inode);

  out:

  	inode_unlock(inode);

  	return 0;
  }
  
  static ssize_t
  rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
  {

  	struct inode *inode = file_inode(filp);

  	struct rpc_pipe *pipe;

  	struct rpc_pipe_msg *msg;
  	int res = 0;

  	inode_lock(inode);

  	pipe = RPC_I(inode)->pipe;
  	if (pipe == NULL) {

  		res = -EPIPE;
  		goto out_unlock;
  	}
  	msg = filp->private_data;
  	if (msg == NULL) {

  		spin_lock(&pipe->lock);
  		if (!list_empty(&pipe->pipe)) {
  			msg = list_entry(pipe->pipe.next,

  					struct rpc_pipe_msg,
  					list);

  			list_move(&msg->list, &pipe->in_upcall);
  			pipe->pipelen -= msg->len;

  			filp->private_data = msg;
  			msg->copied = 0;
  		}

  		spin_unlock(&pipe->lock);

  		if (msg == NULL)
  			goto out_unlock;
  	}
  	/* NOTE: it is up to the callback to update msg->copied */

  	res = pipe->ops->upcall(filp, msg, buf, len);

  	if (res < 0 || msg->len == msg->copied) {
  		filp->private_data = NULL;

  		spin_lock(&pipe->lock);

  		list_del_init(&msg->list);

  		spin_unlock(&pipe->lock);
  		pipe->ops->destroy_msg(msg);

  	}
  out_unlock:

  	inode_unlock(inode);

  	return res;
  }
  
  static ssize_t
  rpc_pipe_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
  {

  	struct inode *inode = file_inode(filp);

  	int res;

  	inode_lock(inode);

  	res = -EPIPE;

  	if (RPC_I(inode)->pipe != NULL)
  		res = RPC_I(inode)->pipe->ops->downcall(filp, buf, len);

  	inode_unlock(inode);

  	return res;
  }

  static __poll_t

  rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
  {

  	struct inode *inode = file_inode(filp);

  	struct rpc_inode *rpci = RPC_I(inode);

  	__poll_t mask = EPOLLOUT | EPOLLWRNORM;

  	poll_wait(filp, &rpci->waitq, wait);

  	inode_lock(inode);

  	if (rpci->pipe == NULL)

  		mask |= EPOLLERR | EPOLLHUP;

  	else if (filp->private_data || !list_empty(&rpci->pipe->pipe))

  		mask |= EPOLLIN | EPOLLRDNORM;

  	inode_unlock(inode);

  	return mask;
  }

  static long
  rpc_pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)

  {

  	struct inode *inode = file_inode(filp);

  	struct rpc_pipe *pipe;

  	int len;
  
  	switch (cmd) {
  	case FIONREAD:

  		inode_lock(inode);

  		pipe = RPC_I(inode)->pipe;
  		if (pipe == NULL) {

  			inode_unlock(inode);

  			return -EPIPE;

  		}

  		spin_lock(&pipe->lock);

  		len = pipe->pipelen;

  		if (filp->private_data) {
  			struct rpc_pipe_msg *msg;

  			msg = filp->private_data;

  			len += msg->len - msg->copied;
  		}

  		spin_unlock(&pipe->lock);

  		inode_unlock(inode);

  		return put_user(len, (int __user *)arg);
  	default:
  		return -EINVAL;
  	}
  }

  static const struct file_operations rpc_pipe_fops = {

  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.read		= rpc_pipe_read,
  	.write		= rpc_pipe_write,
  	.poll		= rpc_pipe_poll,

  	.unlocked_ioctl	= rpc_pipe_ioctl,

  	.open		= rpc_pipe_open,
  	.release	= rpc_pipe_release,
  };
  
  static int
  rpc_show_info(struct seq_file *m, void *v)
  {
  	struct rpc_clnt *clnt = m->private;

  	rcu_read_lock();

  	seq_printf(m, "RPC server: %s
  ",
  			rcu_dereference(clnt->cl_xprt)->servername);

  	seq_printf(m, "service: %s (%d) version %d
  ", clnt->cl_program->name,

  			clnt->cl_prog, clnt->cl_vers);

  	seq_printf(m, "address: %s
  ", rpc_peeraddr2str(clnt, RPC_DISPLAY_ADDR));
  	seq_printf(m, "protocol: %s
  ", rpc_peeraddr2str(clnt, RPC_DISPLAY_PROTO));

  	seq_printf(m, "port: %s
  ", rpc_peeraddr2str(clnt, RPC_DISPLAY_PORT));

  	rcu_read_unlock();

  	return 0;
  }
  
  static int
  rpc_info_open(struct inode *inode, struct file *file)
  {

  	struct rpc_clnt *clnt = NULL;

  	int ret = single_open(file, rpc_show_info, NULL);
  
  	if (!ret) {
  		struct seq_file *m = file->private_data;

  
  		spin_lock(&file->f_path.dentry->d_lock);
  		if (!d_unhashed(file->f_path.dentry))
  			clnt = RPC_I(inode)->private;
  		if (clnt != NULL && atomic_inc_not_zero(&clnt->cl_count)) {
  			spin_unlock(&file->f_path.dentry->d_lock);

  			m->private = clnt;
  		} else {

  			spin_unlock(&file->f_path.dentry->d_lock);

  			single_release(inode, file);
  			ret = -EINVAL;
  		}

  	}
  	return ret;
  }
  
  static int
  rpc_info_release(struct inode *inode, struct file *file)
  {
  	struct seq_file *m = file->private_data;
  	struct rpc_clnt *clnt = (struct rpc_clnt *)m->private;
  
  	if (clnt)
  		rpc_release_client(clnt);
  	return single_release(inode, file);
  }

  static const struct file_operations rpc_info_operations = {

  	.owner		= THIS_MODULE,
  	.open		= rpc_info_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= rpc_info_release,
  };
  
  
  /*

   * Description of fs contents.
   */
  struct rpc_filelist {

  	const char *name;

  	const struct file_operations *i_fop;

  	umode_t mode;

  };

  static struct inode *

  rpc_get_inode(struct super_block *sb, umode_t mode)

  {
  	struct inode *inode = new_inode(sb);
  	if (!inode)
  		return NULL;

  	inode->i_ino = get_next_ino();

  	inode->i_mode = mode;

  	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);

  	switch (mode & S_IFMT) {
  	case S_IFDIR:
  		inode->i_fop = &simple_dir_operations;

  		inode->i_op = &simple_dir_inode_operations;

  		inc_nlink(inode);
  	default:
  		break;

  	}
  	return inode;
  }

  static int __rpc_create_common(struct inode *dir, struct dentry *dentry,
  			       umode_t mode,
  			       const struct file_operations *i_fop,
  			       void *private)
  {
  	struct inode *inode;

  	d_drop(dentry);

  	inode = rpc_get_inode(dir->i_sb, mode);
  	if (!inode)
  		goto out_err;
  	inode->i_ino = iunique(dir->i_sb, 100);
  	if (i_fop)
  		inode->i_fop = i_fop;
  	if (private)
  		rpc_inode_setowner(inode, private);
  	d_add(dentry, inode);
  	return 0;
  out_err:

  	printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %pd
  ",
  			__FILE__, __func__, dentry);

  	dput(dentry);
  	return -ENOMEM;
  }

  static int __rpc_create(struct inode *dir, struct dentry *dentry,
  			umode_t mode,
  			const struct file_operations *i_fop,
  			void *private)
  {
  	int err;
  
  	err = __rpc_create_common(dir, dentry, S_IFREG | mode, i_fop, private);
  	if (err)
  		return err;
  	fsnotify_create(dir, dentry);
  	return 0;
  }

  static int __rpc_mkdir(struct inode *dir, struct dentry *dentry,
  		       umode_t mode,
  		       const struct file_operations *i_fop,
  		       void *private)
  {
  	int err;
  
  	err = __rpc_create_common(dir, dentry, S_IFDIR | mode, i_fop, private);
  	if (err)
  		return err;
  	inc_nlink(dir);
  	fsnotify_mkdir(dir, dentry);
  	return 0;
  }

  static void
  init_pipe(struct rpc_pipe *pipe)
  {
  	pipe->nreaders = 0;
  	pipe->nwriters = 0;
  	INIT_LIST_HEAD(&pipe->in_upcall);
  	INIT_LIST_HEAD(&pipe->in_downcall);
  	INIT_LIST_HEAD(&pipe->pipe);
  	pipe->pipelen = 0;

  	INIT_DELAYED_WORK(&pipe->queue_timeout,
  			    rpc_timeout_upcall_queue);
  	pipe->ops = NULL;
  	spin_lock_init(&pipe->lock);

  	pipe->dentry = NULL;
  }

  void rpc_destroy_pipe_data(struct rpc_pipe *pipe)
  {
  	kfree(pipe);

  }

  EXPORT_SYMBOL_GPL(rpc_destroy_pipe_data);

  struct rpc_pipe *rpc_mkpipe_data(const struct rpc_pipe_ops *ops, int flags)

  {

  	struct rpc_pipe *pipe;

  	pipe = kzalloc(sizeof(struct rpc_pipe), GFP_KERNEL);
  	if (!pipe)

  		return ERR_PTR(-ENOMEM);

  	init_pipe(pipe);

  	pipe->ops = ops;
  	pipe->flags = flags;
  	return pipe;
  }
  EXPORT_SYMBOL_GPL(rpc_mkpipe_data);
  
  static int __rpc_mkpipe_dentry(struct inode *dir, struct dentry *dentry,
  			       umode_t mode,
  			       const struct file_operations *i_fop,
  			       void *private,
  			       struct rpc_pipe *pipe)

  {
  	struct rpc_inode *rpci;
  	int err;
  
  	err = __rpc_create_common(dir, dentry, S_IFIFO | mode, i_fop, private);
  	if (err)
  		return err;

  	rpci = RPC_I(d_inode(dentry));

  	rpci->private = private;

  	rpci->pipe = pipe;

  	fsnotify_create(dir, dentry);
  	return 0;
  }

  static int __rpc_rmdir(struct inode *dir, struct dentry *dentry)
  {
  	int ret;
  
  	dget(dentry);
  	ret = simple_rmdir(dir, dentry);

  	if (!ret)
  		fsnotify_rmdir(dir, dentry);

  	d_delete(dentry);
  	dput(dentry);
  	return ret;
  }

  static int __rpc_unlink(struct inode *dir, struct dentry *dentry)
  {
  	int ret;
  
  	dget(dentry);
  	ret = simple_unlink(dir, dentry);

  	if (!ret)
  		fsnotify_unlink(dir, dentry);

  	d_delete(dentry);
  	dput(dentry);
  	return ret;
  }
  
  static int __rpc_rmpipe(struct inode *dir, struct dentry *dentry)
  {

  	struct inode *inode = d_inode(dentry);

  	rpc_close_pipes(inode);
  	return __rpc_unlink(dir, dentry);
  }

  static struct dentry *__rpc_lookup_create_exclusive(struct dentry *parent,

  					  const char *name)

  {

  	struct qstr q = QSTR_INIT(name, strlen(name));
  	struct dentry *dentry = d_hash_and_lookup(parent, &q);

  	if (!dentry) {

  		dentry = d_alloc(parent, &q);

  		if (!dentry)
  			return ERR_PTR(-ENOMEM);

  	}

  	if (d_really_is_negative(dentry))

  		return dentry;
  	dput(dentry);
  	return ERR_PTR(-EEXIST);
  }

  /*
   * FIXME: This probably has races.
   */

  static void __rpc_depopulate(struct dentry *parent,
  			     const struct rpc_filelist *files,
  			     int start, int eof)

  {

  	struct inode *dir = d_inode(parent);

  	struct dentry *dentry;
  	struct qstr name;
  	int i;

  	for (i = start; i < eof; i++) {
  		name.name = files[i].name;
  		name.len = strlen(files[i].name);

  		dentry = d_hash_and_lookup(parent, &name);

  
  		if (dentry == NULL)

  			continue;

  		if (d_really_is_negative(dentry))

  			goto next;

  		switch (d_inode(dentry)->i_mode & S_IFMT) {

  			default:
  				BUG();
  			case S_IFREG:
  				__rpc_unlink(dir, dentry);

  				break;

  			case S_IFDIR:
  				__rpc_rmdir(dir, dentry);
  		}
  next:
  		dput(dentry);

  	}

  }
  
  static void rpc_depopulate(struct dentry *parent,
  			   const struct rpc_filelist *files,
  			   int start, int eof)
  {

  	struct inode *dir = d_inode(parent);

  	inode_lock_nested(dir, I_MUTEX_CHILD);

  	__rpc_depopulate(parent, files, start, eof);

  	inode_unlock(dir);

  }

  static int rpc_populate(struct dentry *parent,
  			const struct rpc_filelist *files,
  			int start, int eof,
  			void *private)

  {

  	struct inode *dir = d_inode(parent);

  	struct dentry *dentry;

  	int i, err;

  	inode_lock(dir);

  	for (i = start; i < eof; i++) {

  		dentry = __rpc_lookup_create_exclusive(parent, files[i].name);

  		err = PTR_ERR(dentry);
  		if (IS_ERR(dentry))

  			goto out_bad;

  		switch (files[i].mode & S_IFMT) {
  			default:
  				BUG();
  			case S_IFREG:
  				err = __rpc_create(dir, dentry,
  						files[i].mode,
  						files[i].i_fop,
  						private);
  				break;
  			case S_IFDIR:
  				err = __rpc_mkdir(dir, dentry,
  						files[i].mode,
  						NULL,
  						private);

  		}

  		if (err != 0)
  			goto out_bad;

  	}

  	inode_unlock(dir);

  	return 0;
  out_bad:

  	__rpc_depopulate(parent, files, start, eof);

  	inode_unlock(dir);

  	printk(KERN_WARNING "%s: %s failed to populate directory %pd
  ",
  			__FILE__, __func__, parent);

  	return err;

  }

  static struct dentry *rpc_mkdir_populate(struct dentry *parent,

  		const char *name, umode_t mode, void *private,

  		int (*populate)(struct dentry *, void *), void *args_populate)

  {

  	struct dentry *dentry;

  	struct inode *dir = d_inode(parent);

  	int error;

  	inode_lock_nested(dir, I_MUTEX_PARENT);

  	dentry = __rpc_lookup_create_exclusive(parent, name);

  	if (IS_ERR(dentry))

  		goto out;
  	error = __rpc_mkdir(dir, dentry, mode, NULL, private);

  	if (error != 0)
  		goto out_err;

  	if (populate != NULL) {
  		error = populate(dentry, args_populate);
  		if (error)
  			goto err_rmdir;
  	}

  out:

  	inode_unlock(dir);

  	return dentry;

  err_rmdir:

  	__rpc_rmdir(dir, dentry);

  out_err:

  	dentry = ERR_PTR(error);
  	goto out;

  }

  static int rpc_rmdir_depopulate(struct dentry *dentry,
  		void (*depopulate)(struct dentry *))

  {

  	struct dentry *parent;

  	struct inode *dir;
  	int error;

  	parent = dget_parent(dentry);

  	dir = d_inode(parent);

  	inode_lock_nested(dir, I_MUTEX_PARENT);

  	if (depopulate != NULL)
  		depopulate(dentry);

  	error = __rpc_rmdir(dir, dentry);

  	inode_unlock(dir);

  	dput(parent);

  	return error;

  }

  /**
   * rpc_mkpipe - make an rpc_pipefs file for kernel<->userspace communication
   * @parent: dentry of directory to create new "pipe" in
   * @name: name of pipe
   * @private: private data to associate with the pipe, for the caller's use

   * @pipe: &rpc_pipe containing input parameters

   *
   * Data is made available for userspace to read by calls to
   * rpc_queue_upcall().  The actual reads will result in calls to
   * @ops->upcall, which will be called with the file pointer,
   * message, and userspace buffer to copy to.
   *
   * Writes can come at any time, and do not necessarily have to be
   * responses to upcalls.  They will result in calls to @msg->downcall.
   *
   * The @private argument passed here will be available to all these methods

   * from the file pointer, via RPC_I(file_inode(file))->private.

   */

  struct dentry *rpc_mkpipe_dentry(struct dentry *parent, const char *name,
  				 void *private, struct rpc_pipe *pipe)

  {

  	struct dentry *dentry;

  	struct inode *dir = d_inode(parent);

  	umode_t umode = S_IFIFO | 0600;

  	int err;

  	if (pipe->ops->upcall == NULL)

  		umode &= ~0444;

  	if (pipe->ops->downcall == NULL)

  		umode &= ~0222;

  	inode_lock_nested(dir, I_MUTEX_PARENT);

  	dentry = __rpc_lookup_create_exclusive(parent, name);

  	if (IS_ERR(dentry))

  		goto out;

  	err = __rpc_mkpipe_dentry(dir, dentry, umode, &rpc_pipe_fops,
  				  private, pipe);

  	if (err)
  		goto out_err;

  out:

  	inode_unlock(dir);

  	return dentry;

  out_err:
  	dentry = ERR_PTR(err);

  	printk(KERN_WARNING "%s: %s() failed to create pipe %pd/%s (errno = %d)
  ",
  			__FILE__, __func__, parent, name,

  			err);

  	goto out;

  }

  EXPORT_SYMBOL_GPL(rpc_mkpipe_dentry);

  /**
   * rpc_unlink - remove a pipe
   * @dentry: dentry for the pipe, as returned from rpc_mkpipe
   *
   * After this call, lookups will no longer find the pipe, and any
   * attempts to read or write using preexisting opens of the pipe will
   * return -EPIPE.
   */

  int

  rpc_unlink(struct dentry *dentry)

  {

  	struct dentry *parent;

  	struct inode *dir;

  	int error = 0;

  	parent = dget_parent(dentry);

  	dir = d_inode(parent);

  	inode_lock_nested(dir, I_MUTEX_PARENT);

  	error = __rpc_rmpipe(dir, dentry);

  	inode_unlock(dir);

  	dput(parent);

  	return error;

  }

  EXPORT_SYMBOL_GPL(rpc_unlink);

  /**
   * rpc_init_pipe_dir_head - initialise a struct rpc_pipe_dir_head
   * @pdh: pointer to struct rpc_pipe_dir_head
   */
  void rpc_init_pipe_dir_head(struct rpc_pipe_dir_head *pdh)
  {
  	INIT_LIST_HEAD(&pdh->pdh_entries);
  	pdh->pdh_dentry = NULL;
  }
  EXPORT_SYMBOL_GPL(rpc_init_pipe_dir_head);
  
  /**
   * rpc_init_pipe_dir_object - initialise a struct rpc_pipe_dir_object
   * @pdo: pointer to struct rpc_pipe_dir_object
   * @pdo_ops: pointer to const struct rpc_pipe_dir_object_ops
   * @pdo_data: pointer to caller-defined data
   */
  void rpc_init_pipe_dir_object(struct rpc_pipe_dir_object *pdo,
  		const struct rpc_pipe_dir_object_ops *pdo_ops,
  		void *pdo_data)
  {
  	INIT_LIST_HEAD(&pdo->pdo_head);
  	pdo->pdo_ops = pdo_ops;
  	pdo->pdo_data = pdo_data;
  }
  EXPORT_SYMBOL_GPL(rpc_init_pipe_dir_object);
  
  static int
  rpc_add_pipe_dir_object_locked(struct net *net,
  		struct rpc_pipe_dir_head *pdh,
  		struct rpc_pipe_dir_object *pdo)
  {
  	int ret = 0;
  
  	if (pdh->pdh_dentry)
  		ret = pdo->pdo_ops->create(pdh->pdh_dentry, pdo);
  	if (ret == 0)
  		list_add_tail(&pdo->pdo_head, &pdh->pdh_entries);
  	return ret;
  }
  
  static void
  rpc_remove_pipe_dir_object_locked(struct net *net,
  		struct rpc_pipe_dir_head *pdh,
  		struct rpc_pipe_dir_object *pdo)
  {
  	if (pdh->pdh_dentry)
  		pdo->pdo_ops->destroy(pdh->pdh_dentry, pdo);
  	list_del_init(&pdo->pdo_head);
  }
  
  /**
   * rpc_add_pipe_dir_object - associate a rpc_pipe_dir_object to a directory
   * @net: pointer to struct net
   * @pdh: pointer to struct rpc_pipe_dir_head
   * @pdo: pointer to struct rpc_pipe_dir_object
   *
   */
  int
  rpc_add_pipe_dir_object(struct net *net,
  		struct rpc_pipe_dir_head *pdh,
  		struct rpc_pipe_dir_object *pdo)
  {
  	int ret = 0;
  
  	if (list_empty(&pdo->pdo_head)) {
  		struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  
  		mutex_lock(&sn->pipefs_sb_lock);
  		ret = rpc_add_pipe_dir_object_locked(net, pdh, pdo);
  		mutex_unlock(&sn->pipefs_sb_lock);
  	}
  	return ret;
  }
  EXPORT_SYMBOL_GPL(rpc_add_pipe_dir_object);
  
  /**
   * rpc_remove_pipe_dir_object - remove a rpc_pipe_dir_object from a directory
   * @net: pointer to struct net
   * @pdh: pointer to struct rpc_pipe_dir_head
   * @pdo: pointer to struct rpc_pipe_dir_object
   *
   */
  void
  rpc_remove_pipe_dir_object(struct net *net,
  		struct rpc_pipe_dir_head *pdh,
  		struct rpc_pipe_dir_object *pdo)
  {
  	if (!list_empty(&pdo->pdo_head)) {
  		struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  
  		mutex_lock(&sn->pipefs_sb_lock);
  		rpc_remove_pipe_dir_object_locked(net, pdh, pdo);
  		mutex_unlock(&sn->pipefs_sb_lock);
  	}
  }
  EXPORT_SYMBOL_GPL(rpc_remove_pipe_dir_object);

  /**
   * rpc_find_or_alloc_pipe_dir_object
   * @net: pointer to struct net
   * @pdh: pointer to struct rpc_pipe_dir_head
   * @match: match struct rpc_pipe_dir_object to data
   * @alloc: allocate a new struct rpc_pipe_dir_object
   * @data: user defined data for match() and alloc()
   *
   */
  struct rpc_pipe_dir_object *
  rpc_find_or_alloc_pipe_dir_object(struct net *net,
  		struct rpc_pipe_dir_head *pdh,
  		int (*match)(struct rpc_pipe_dir_object *, void *),
  		struct rpc_pipe_dir_object *(*alloc)(void *),
  		void *data)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct rpc_pipe_dir_object *pdo;
  
  	mutex_lock(&sn->pipefs_sb_lock);
  	list_for_each_entry(pdo, &pdh->pdh_entries, pdo_head) {
  		if (!match(pdo, data))
  			continue;
  		goto out;
  	}
  	pdo = alloc(data);
  	if (!pdo)
  		goto out;
  	rpc_add_pipe_dir_object_locked(net, pdh, pdo);
  out:
  	mutex_unlock(&sn->pipefs_sb_lock);
  	return pdo;
  }
  EXPORT_SYMBOL_GPL(rpc_find_or_alloc_pipe_dir_object);

  static void
  rpc_create_pipe_dir_objects(struct rpc_pipe_dir_head *pdh)
  {
  	struct rpc_pipe_dir_object *pdo;
  	struct dentry *dir = pdh->pdh_dentry;
  
  	list_for_each_entry(pdo, &pdh->pdh_entries, pdo_head)
  		pdo->pdo_ops->create(dir, pdo);
  }
  
  static void
  rpc_destroy_pipe_dir_objects(struct rpc_pipe_dir_head *pdh)
  {
  	struct rpc_pipe_dir_object *pdo;
  	struct dentry *dir = pdh->pdh_dentry;
  
  	list_for_each_entry(pdo, &pdh->pdh_entries, pdo_head)
  		pdo->pdo_ops->destroy(dir, pdo);
  }

  enum {
  	RPCAUTH_info,
  	RPCAUTH_EOF
  };
  
  static const struct rpc_filelist authfiles[] = {
  	[RPCAUTH_info] = {
  		.name = "info",
  		.i_fop = &rpc_info_operations,

  		.mode = S_IFREG | 0400,

  	},
  };
  
  static int rpc_clntdir_populate(struct dentry *dentry, void *private)
  {
  	return rpc_populate(dentry,
  			    authfiles, RPCAUTH_info, RPCAUTH_EOF,
  			    private);
  }
  
  static void rpc_clntdir_depopulate(struct dentry *dentry)
  {
  	rpc_depopulate(dentry, authfiles, RPCAUTH_info, RPCAUTH_EOF);
  }

  /**
   * rpc_create_client_dir - Create a new rpc_client directory in rpc_pipefs

   * @dentry: the parent of new directory
   * @name: the name of new directory

   * @rpc_client: rpc client to associate with this directory
   *
   * This creates a directory at the given @path associated with
   * @rpc_clnt, which will contain a file named "info" with some basic
   * information about the client, together with any "pipes" that may
   * later be created using rpc_mkpipe().
   */

  struct dentry *rpc_create_client_dir(struct dentry *dentry,

  				   const char *name,

  				   struct rpc_clnt *rpc_client)
  {

  	struct dentry *ret;

  	ret = rpc_mkdir_populate(dentry, name, 0555, NULL,
  				 rpc_clntdir_populate, rpc_client);

  	if (!IS_ERR(ret)) {
  		rpc_client->cl_pipedir_objects.pdh_dentry = ret;
  		rpc_create_pipe_dir_objects(&rpc_client->cl_pipedir_objects);
  	}
  	return ret;

  }
  
  /**
   * rpc_remove_client_dir - Remove a directory created with rpc_create_client_dir()

   * @rpc_client: rpc_client for the pipe

   */

  int rpc_remove_client_dir(struct rpc_clnt *rpc_client)

  {

  	struct dentry *dentry = rpc_client->cl_pipedir_objects.pdh_dentry;
  
  	if (dentry == NULL)
  		return 0;
  	rpc_destroy_pipe_dir_objects(&rpc_client->cl_pipedir_objects);
  	rpc_client->cl_pipedir_objects.pdh_dentry = NULL;

  	return rpc_rmdir_depopulate(dentry, rpc_clntdir_depopulate);

  }

  static const struct rpc_filelist cache_pipefs_files[3] = {
  	[0] = {
  		.name = "channel",
  		.i_fop = &cache_file_operations_pipefs,

  		.mode = S_IFREG | 0600,

  	},
  	[1] = {
  		.name = "content",
  		.i_fop = &content_file_operations_pipefs,

  		.mode = S_IFREG | 0400,

  	},
  	[2] = {
  		.name = "flush",
  		.i_fop = &cache_flush_operations_pipefs,

  		.mode = S_IFREG | 0600,

  	},
  };
  
  static int rpc_cachedir_populate(struct dentry *dentry, void *private)
  {
  	return rpc_populate(dentry,
  			    cache_pipefs_files, 0, 3,
  			    private);
  }
  
  static void rpc_cachedir_depopulate(struct dentry *dentry)
  {
  	rpc_depopulate(dentry, cache_pipefs_files, 0, 3);
  }

  struct dentry *rpc_create_cache_dir(struct dentry *parent, const char *name,

  				    umode_t umode, struct cache_detail *cd)

  {
  	return rpc_mkdir_populate(parent, name, umode, NULL,
  			rpc_cachedir_populate, cd);
  }
  
  void rpc_remove_cache_dir(struct dentry *dentry)
  {
  	rpc_rmdir_depopulate(dentry, rpc_cachedir_depopulate);
  }

  /*
   * populate the filesystem
   */

  static const struct super_operations s_ops = {

  	.alloc_inode	= rpc_alloc_inode,

  	.free_inode	= rpc_free_inode,

  	.statfs		= simple_statfs,
  };
  
  #define RPCAUTH_GSSMAGIC 0x67596969

  /*
   * We have a single directory with 1 node in it.
   */
  enum {
  	RPCAUTH_lockd,
  	RPCAUTH_mount,
  	RPCAUTH_nfs,
  	RPCAUTH_portmap,
  	RPCAUTH_statd,
  	RPCAUTH_nfsd4_cb,

  	RPCAUTH_cache,

  	RPCAUTH_nfsd,

  	RPCAUTH_gssd,

  	RPCAUTH_RootEOF
  };
  
  static const struct rpc_filelist files[] = {
  	[RPCAUTH_lockd] = {
  		.name = "lockd",

  		.mode = S_IFDIR | 0555,

  	},
  	[RPCAUTH_mount] = {
  		.name = "mount",

  		.mode = S_IFDIR | 0555,

  	},
  	[RPCAUTH_nfs] = {
  		.name = "nfs",

  		.mode = S_IFDIR | 0555,

  	},
  	[RPCAUTH_portmap] = {
  		.name = "portmap",

  		.mode = S_IFDIR | 0555,

  	},
  	[RPCAUTH_statd] = {
  		.name = "statd",

  		.mode = S_IFDIR | 0555,

  	},
  	[RPCAUTH_nfsd4_cb] = {
  		.name = "nfsd4_cb",

  		.mode = S_IFDIR | 0555,

  	},

  	[RPCAUTH_cache] = {
  		.name = "cache",

  		.mode = S_IFDIR | 0555,

  	},

  	[RPCAUTH_nfsd] = {
  		.name = "nfsd",

  		.mode = S_IFDIR | 0555,

  	},

  	[RPCAUTH_gssd] = {
  		.name = "gssd",

  		.mode = S_IFDIR | 0555,

  	},

  };

  /*
   * This call can be used only in RPC pipefs mount notification hooks.
   */
  struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
  			       const unsigned char *dir_name)
  {

  	struct qstr dir = QSTR_INIT(dir_name, strlen(dir_name));

  	return d_hash_and_lookup(sb->s_root, &dir);

  }
  EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);

  int rpc_pipefs_init_net(struct net *net)

  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

  	sn->gssd_dummy = rpc_mkpipe_data(&gssd_dummy_pipe_ops, 0);
  	if (IS_ERR(sn->gssd_dummy))
  		return PTR_ERR(sn->gssd_dummy);

  	mutex_init(&sn->pipefs_sb_lock);

  	sn->pipe_version = -1;

  	return 0;
  }
  
  void rpc_pipefs_exit_net(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  
  	rpc_destroy_pipe_data(sn->gssd_dummy);

  }
  
  /*
   * This call will be used for per network namespace operations calls.
   * Note: Function will be returned with pipefs_sb_lock taken if superblock was
   * found. This lock have to be released by rpc_put_sb_net() when all operations
   * will be completed.
   */
  struct super_block *rpc_get_sb_net(const struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  
  	mutex_lock(&sn->pipefs_sb_lock);
  	if (sn->pipefs_sb)
  		return sn->pipefs_sb;
  	mutex_unlock(&sn->pipefs_sb_lock);
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(rpc_get_sb_net);
  
  void rpc_put_sb_net(const struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

  	WARN_ON(sn->pipefs_sb == NULL);

  	mutex_unlock(&sn->pipefs_sb_lock);
  }
  EXPORT_SYMBOL_GPL(rpc_put_sb_net);

  static const struct rpc_filelist gssd_dummy_clnt_dir[] = {
  	[0] = {
  		.name = "clntXX",

  		.mode = S_IFDIR | 0555,

  	},
  };
  
  static ssize_t
  dummy_downcall(struct file *filp, const char __user *src, size_t len)
  {
  	return -EINVAL;
  }
  
  static const struct rpc_pipe_ops gssd_dummy_pipe_ops = {
  	.upcall		= rpc_pipe_generic_upcall,
  	.downcall	= dummy_downcall,
  };

  /*
   * Here we present a bogus "info" file to keep rpc.gssd happy. We don't expect
   * that it will ever use this info to handle an upcall, but rpc.gssd expects
   * that this file will be there and have a certain format.
   */
  static int

  rpc_dummy_info_show(struct seq_file *m, void *v)

  {
  	seq_printf(m, "RPC server: %s
  ", utsname()->nodename);
  	seq_printf(m, "service: foo (1) version 0
  ");
  	seq_printf(m, "address: 127.0.0.1
  ");
  	seq_printf(m, "protocol: tcp
  ");
  	seq_printf(m, "port: 0
  ");
  	return 0;
  }

  DEFINE_SHOW_ATTRIBUTE(rpc_dummy_info);

  
  static const struct rpc_filelist gssd_dummy_info_file[] = {
  	[0] = {
  		.name = "info",

  		.i_fop = &rpc_dummy_info_fops,

  		.mode = S_IFREG | 0400,

  	},
  };

  /**
   * rpc_gssd_dummy_populate - create a dummy gssd pipe
   * @root:	root of the rpc_pipefs filesystem
   * @pipe_data:	pipe data created when netns is initialized
   *
   * Create a dummy set of directories and a pipe that gssd can hold open to
   * indicate that it is up and running.
   */
  static struct dentry *
  rpc_gssd_dummy_populate(struct dentry *root, struct rpc_pipe *pipe_data)
  {
  	int ret = 0;
  	struct dentry *gssd_dentry;
  	struct dentry *clnt_dentry = NULL;
  	struct dentry *pipe_dentry = NULL;
  	struct qstr q = QSTR_INIT(files[RPCAUTH_gssd].name,
  				  strlen(files[RPCAUTH_gssd].name));
  
  	/* We should never get this far if "gssd" doesn't exist */
  	gssd_dentry = d_hash_and_lookup(root, &q);
  	if (!gssd_dentry)
  		return ERR_PTR(-ENOENT);
  
  	ret = rpc_populate(gssd_dentry, gssd_dummy_clnt_dir, 0, 1, NULL);
  	if (ret) {
  		pipe_dentry = ERR_PTR(ret);
  		goto out;
  	}
  
  	q.name = gssd_dummy_clnt_dir[0].name;
  	q.len = strlen(gssd_dummy_clnt_dir[0].name);
  	clnt_dentry = d_hash_and_lookup(gssd_dentry, &q);
  	if (!clnt_dentry) {

  		__rpc_depopulate(gssd_dentry, gssd_dummy_clnt_dir, 0, 1);

  		pipe_dentry = ERR_PTR(-ENOENT);
  		goto out;
  	}

  	ret = rpc_populate(clnt_dentry, gssd_dummy_info_file, 0, 1, NULL);
  	if (ret) {
  		__rpc_depopulate(gssd_dentry, gssd_dummy_clnt_dir, 0, 1);
  		pipe_dentry = ERR_PTR(ret);
  		goto out;
  	}

  	pipe_dentry = rpc_mkpipe_dentry(clnt_dentry, "gssd", NULL, pipe_data);

  	if (IS_ERR(pipe_dentry)) {
  		__rpc_depopulate(clnt_dentry, gssd_dummy_info_file, 0, 1);

  		__rpc_depopulate(gssd_dentry, gssd_dummy_clnt_dir, 0, 1);

  	}

  out:
  	dput(clnt_dentry);
  	dput(gssd_dentry);
  	return pipe_dentry;
  }

  static void
  rpc_gssd_dummy_depopulate(struct dentry *pipe_dentry)
  {
  	struct dentry *clnt_dir = pipe_dentry->d_parent;
  	struct dentry *gssd_dir = clnt_dir->d_parent;

  	dget(pipe_dentry);

  	__rpc_rmpipe(d_inode(clnt_dir), pipe_dentry);

  	__rpc_depopulate(clnt_dir, gssd_dummy_info_file, 0, 1);
  	__rpc_depopulate(gssd_dir, gssd_dummy_clnt_dir, 0, 1);
  	dput(pipe_dentry);
  }

  static int

  rpc_fill_super(struct super_block *sb, struct fs_context *fc)

  {
  	struct inode *inode;

  	struct dentry *root, *gssd_dentry;

  	struct net *net = sb->s_fs_info;

  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

  	int err;

  	sb->s_blocksize = PAGE_SIZE;
  	sb->s_blocksize_bits = PAGE_SHIFT;

  	sb->s_magic = RPCAUTH_GSSMAGIC;
  	sb->s_op = &s_ops;

  	sb->s_d_op = &simple_dentry_operations;

  	sb->s_time_gran = 1;

  	inode = rpc_get_inode(sb, S_IFDIR | 0555);

  	sb->s_root = root = d_make_root(inode);
  	if (!root)

  		return -ENOMEM;

  	if (rpc_populate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF, NULL))

  		return -ENOMEM;

  
  	gssd_dentry = rpc_gssd_dummy_populate(root, sn->gssd_dummy);
  	if (IS_ERR(gssd_dentry)) {
  		__rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);
  		return PTR_ERR(gssd_dentry);
  	}

  	dprintk("RPC:       sending pipefs MOUNT notification for net %x%s
  ",
  		net->ns.inum, NET_NAME(net));

  	mutex_lock(&sn->pipefs_sb_lock);

  	sn->pipefs_sb = sb;

  	err = blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
  					   RPC_PIPEFS_MOUNT,
  					   sb);
  	if (err)
  		goto err_depopulate;

  	mutex_unlock(&sn->pipefs_sb_lock);

  	return 0;

  
  err_depopulate:

  	rpc_gssd_dummy_depopulate(gssd_dentry);

  	blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
  					   RPC_PIPEFS_UMOUNT,
  					   sb);

  	sn->pipefs_sb = NULL;

  	__rpc_depopulate(root, files, RPCAUTH_lockd, RPCAUTH_RootEOF);

  	mutex_unlock(&sn->pipefs_sb_lock);

  	return err;

  }

  bool
  gssd_running(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct rpc_pipe *pipe = sn->gssd_dummy;
  
  	return pipe->nreaders || pipe->nwriters;
  }
  EXPORT_SYMBOL_GPL(gssd_running);

  static int rpc_fs_get_tree(struct fs_context *fc)
  {

  	return get_tree_keyed(fc, rpc_fill_super, get_net(fc->net_ns));

  }
  
  static void rpc_fs_free_fc(struct fs_context *fc)

  {

  	if (fc->s_fs_info)
  		put_net(fc->s_fs_info);
  }
  
  static const struct fs_context_operations rpc_fs_context_ops = {
  	.free		= rpc_fs_free_fc,
  	.get_tree	= rpc_fs_get_tree,
  };
  
  static int rpc_init_fs_context(struct fs_context *fc)
  {
  	put_user_ns(fc->user_ns);
  	fc->user_ns = get_user_ns(fc->net_ns->user_ns);
  	fc->ops = &rpc_fs_context_ops;
  	return 0;

  }

  static void rpc_kill_sb(struct super_block *sb)

  {
  	struct net *net = sb->s_fs_info;

  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);

  	mutex_lock(&sn->pipefs_sb_lock);

  	if (sn->pipefs_sb != sb) {
  		mutex_unlock(&sn->pipefs_sb_lock);
  		goto out;
  	}

  	sn->pipefs_sb = NULL;

  	dprintk("RPC:       sending pipefs UMOUNT notification for net %x%s
  ",
  		net->ns.inum, NET_NAME(net));

  	blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
  					   RPC_PIPEFS_UMOUNT,
  					   sb);

  	mutex_unlock(&sn->pipefs_sb_lock);

  out:

  	kill_litter_super(sb);

  	put_net(net);

  }
  
  static struct file_system_type rpc_pipe_fs_type = {
  	.owner		= THIS_MODULE,
  	.name		= "rpc_pipefs",

  	.init_fs_context = rpc_init_fs_context,

  	.kill_sb	= rpc_kill_sb,

  };

  MODULE_ALIAS_FS("rpc_pipefs");

  MODULE_ALIAS("rpc_pipefs");

  
  static void

  init_once(void *foo)

  {
  	struct rpc_inode *rpci = (struct rpc_inode *) foo;

  	inode_init_once(&rpci->vfs_inode);
  	rpci->private = NULL;

  	rpci->pipe = NULL;

  	init_waitqueue_head(&rpci->waitq);

  }
  
  int register_rpc_pipefs(void)
  {

  	int err;

  	rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",

  				sizeof(struct rpc_inode),
  				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|

  						SLAB_MEM_SPREAD|SLAB_ACCOUNT),

  				init_once);

  	if (!rpc_inode_cachep)
  		return -ENOMEM;

  	err = rpc_clients_notifier_register();
  	if (err)
  		goto err_notifier;

  	err = register_filesystem(&rpc_pipe_fs_type);

  	if (err)
  		goto err_register;

  	return 0;

  
  err_register:
  	rpc_clients_notifier_unregister();
  err_notifier:
  	kmem_cache_destroy(rpc_inode_cachep);
  	return err;

  }
  
  void unregister_rpc_pipefs(void)
  {

  	rpc_clients_notifier_unregister();

  	unregister_filesystem(&rpc_pipe_fs_type);

  	kmem_cache_destroy(rpc_inode_cachep);

  }