/* -*- c -*- --------------------------------------------------------------- *
   *
   * linux/fs/autofs/root.c
   *
   *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>

   *  Copyright 2001-2006 Ian Kent <raven@themaw.net>

   *
   * This file is part of the Linux kernel and is made available under
   * the terms of the GNU General Public License, version 2, or at your
   * option, any later version, incorporated herein by reference.
   *
   * ------------------------------------------------------------------------- */

  #include <linux/capability.h>

  #include <linux/errno.h>
  #include <linux/stat.h>

  #include <linux/slab.h>

  #include <linux/param.h>
  #include <linux/time.h>

  #include <linux/compat.h>

  #include <linux/mutex.h>

  #include "autofs_i.h"
  
  static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
  static int autofs4_dir_unlink(struct inode *,struct dentry *);
  static int autofs4_dir_rmdir(struct inode *,struct dentry *);

  static int autofs4_dir_mkdir(struct inode *,struct dentry *,umode_t);

  static long autofs4_root_ioctl(struct file *,unsigned int,unsigned long);

  #ifdef CONFIG_COMPAT

  static long autofs4_root_compat_ioctl(struct file *,unsigned int,unsigned long);

  #endif

  static int autofs4_dir_open(struct inode *inode, struct file *file);

  static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);

  static struct vfsmount *autofs4_d_automount(struct path *);

  static int autofs4_d_manage(struct dentry *, bool);

  static void autofs4_dentry_release(struct dentry *);

  const struct file_operations autofs4_root_operations = {

  	.open		= dcache_dir_open,
  	.release	= dcache_dir_close,
  	.read		= generic_read_dir,

  	.readdir	= dcache_readdir,

  	.llseek		= dcache_dir_lseek,

  	.unlocked_ioctl	= autofs4_root_ioctl,

  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= autofs4_root_compat_ioctl,
  #endif

  };

  const struct file_operations autofs4_dir_operations = {

  	.open		= autofs4_dir_open,

  	.release	= dcache_dir_close,

  	.read		= generic_read_dir,

  	.readdir	= dcache_readdir,

  	.llseek		= dcache_dir_lseek,

  };

  const struct inode_operations autofs4_dir_inode_operations = {

  	.lookup		= autofs4_lookup,
  	.unlink		= autofs4_dir_unlink,
  	.symlink	= autofs4_dir_symlink,
  	.mkdir		= autofs4_dir_mkdir,
  	.rmdir		= autofs4_dir_rmdir,
  };

  const struct dentry_operations autofs4_dentry_operations = {

  	.d_automount	= autofs4_d_automount,
  	.d_manage	= autofs4_d_manage,
  	.d_release	= autofs4_dentry_release,
  };

  static void autofs4_add_active(struct dentry *dentry)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);
  	if (ino) {
  		spin_lock(&sbi->lookup_lock);
  		if (!ino->active_count) {
  			if (list_empty(&ino->active))
  				list_add(&ino->active, &sbi->active_list);
  		}
  		ino->active_count++;
  		spin_unlock(&sbi->lookup_lock);
  	}
  	return;
  }
  
  static void autofs4_del_active(struct dentry *dentry)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);
  	if (ino) {
  		spin_lock(&sbi->lookup_lock);
  		ino->active_count--;
  		if (!ino->active_count) {
  			if (!list_empty(&ino->active))
  				list_del_init(&ino->active);
  		}
  		spin_unlock(&sbi->lookup_lock);
  	}
  	return;
  }

  static int autofs4_dir_open(struct inode *inode, struct file *file)
  {

  	struct dentry *dentry = file->f_path.dentry;

  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);

  	DPRINTK("file=%p dentry=%p %.*s",
  		file, dentry, dentry->d_name.len, dentry->d_name.name);
  
  	if (autofs4_oz_mode(sbi))
  		goto out;

  	/*
  	 * An empty directory in an autofs file system is always a
  	 * mount point. The daemon must have failed to mount this
  	 * during lookup so it doesn't exist. This can happen, for
  	 * example, if user space returns an incorrect status for a
  	 * mount request. Otherwise we're doing a readdir on the
  	 * autofs file system so just let the libfs routines handle
  	 * it.
  	 */

  	spin_lock(&sbi->lookup_lock);

  	spin_lock(&dentry->d_lock);

  	if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {

  		spin_unlock(&dentry->d_lock);

  		spin_unlock(&sbi->lookup_lock);

  		return -ENOENT;

  	}

  	spin_unlock(&dentry->d_lock);

  	spin_unlock(&sbi->lookup_lock);

  out:

  	return dcache_dir_open(inode, file);

  }

  static void autofs4_dentry_release(struct dentry *de)

  {

  	struct autofs_info *ino = autofs4_dentry_ino(de);
  	struct autofs_sb_info *sbi = autofs4_sbi(de->d_sb);

  
  	DPRINTK("releasing %p", de);

  	if (!ino)
  		return;
  
  	if (sbi) {
  		spin_lock(&sbi->lookup_lock);
  		if (!list_empty(&ino->active))
  			list_del(&ino->active);
  		if (!list_empty(&ino->expiring))
  			list_del(&ino->expiring);
  		spin_unlock(&sbi->lookup_lock);

  	}

  
  	autofs4_free_ino(ino);

  }

  static struct dentry *autofs4_lookup_active(struct dentry *dentry)

  {

  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct dentry *parent = dentry->d_parent;
  	struct qstr *name = &dentry->d_name;

  	unsigned int len = name->len;
  	unsigned int hash = name->hash;
  	const unsigned char *str = name->name;
  	struct list_head *p, *head;

  	spin_lock(&sbi->lookup_lock);
  	head = &sbi->active_list;
  	list_for_each(p, head) {
  		struct autofs_info *ino;

  		struct dentry *active;

  		struct qstr *qstr;
  
  		ino = list_entry(p, struct autofs_info, active);

  		active = ino->dentry;

  		spin_lock(&active->d_lock);

  
  		/* Already gone? */

  		if (active->d_count == 0)

  			goto next;

  		qstr = &active->d_name;

  		if (active->d_name.hash != hash)

  			goto next;

  		if (active->d_parent != parent)

  			goto next;
  
  		if (qstr->len != len)
  			goto next;
  		if (memcmp(qstr->name, str, len))
  			goto next;

  		if (d_unhashed(active)) {

  			dget_dlock(active);

  			spin_unlock(&active->d_lock);
  			spin_unlock(&sbi->lookup_lock);

  			return active;
  		}

  next:

  		spin_unlock(&active->d_lock);

  	}
  	spin_unlock(&sbi->lookup_lock);

  
  	return NULL;
  }

  static struct dentry *autofs4_lookup_expiring(struct dentry *dentry)

  {

  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct dentry *parent = dentry->d_parent;
  	struct qstr *name = &dentry->d_name;

  	unsigned int len = name->len;
  	unsigned int hash = name->hash;
  	const unsigned char *str = name->name;
  	struct list_head *p, *head;

  	spin_lock(&sbi->lookup_lock);
  	head = &sbi->expiring_list;

  	list_for_each(p, head) {
  		struct autofs_info *ino;

  		struct dentry *expiring;

  		struct qstr *qstr;

  		ino = list_entry(p, struct autofs_info, expiring);

  		expiring = ino->dentry;

  		spin_lock(&expiring->d_lock);

  
  		/* Bad luck, we've already been dentry_iput */

  		if (!expiring->d_inode)

  			goto next;

  		qstr = &expiring->d_name;

  		if (expiring->d_name.hash != hash)

  			goto next;

  		if (expiring->d_parent != parent)

  			goto next;
  
  		if (qstr->len != len)
  			goto next;
  		if (memcmp(qstr->name, str, len))
  			goto next;

  		if (d_unhashed(expiring)) {

  			dget_dlock(expiring);

  			spin_unlock(&expiring->d_lock);
  			spin_unlock(&sbi->lookup_lock);

  			return expiring;
  		}

  next:

  		spin_unlock(&expiring->d_lock);

  	}

  	spin_unlock(&sbi->lookup_lock);

  
  	return NULL;
  }

  static int autofs4_mount_wait(struct dentry *dentry)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);

  	int status = 0;

  
  	if (ino->flags & AUTOFS_INF_PENDING) {
  		DPRINTK("waiting for mount name=%.*s",
  			dentry->d_name.len, dentry->d_name.name);
  		status = autofs4_wait(sbi, dentry, NFY_MOUNT);
  		DPRINTK("mount wait done status=%d", status);

  	}

  	ino->last_used = jiffies;
  	return status;

  }
  
  static int do_expire_wait(struct dentry *dentry)
  {
  	struct dentry *expiring;
  
  	expiring = autofs4_lookup_expiring(dentry);
  	if (!expiring)
  		return autofs4_expire_wait(dentry);
  	else {
  		/*
  		 * If we are racing with expire the request might not
  		 * be quite complete, but the directory has been removed
  		 * so it must have been successful, just wait for it.
  		 */
  		autofs4_expire_wait(expiring);
  		autofs4_del_expiring(expiring);
  		dput(expiring);
  	}
  	return 0;
  }
  
  static struct dentry *autofs4_mountpoint_changed(struct path *path)
  {
  	struct dentry *dentry = path->dentry;
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  
  	/*
  	 * If this is an indirect mount the dentry could have gone away
  	 * as a result of an expire and a new one created.
  	 */
  	if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
  		struct dentry *parent = dentry->d_parent;

  		struct autofs_info *ino;

  		struct dentry *new = d_lookup(parent, &dentry->d_name);
  		if (!new)
  			return NULL;

  		ino = autofs4_dentry_ino(new);
  		ino->last_used = jiffies;

  		dput(path->dentry);
  		path->dentry = new;
  	}
  	return path->dentry;
  }

  static struct vfsmount *autofs4_d_automount(struct path *path)

  {
  	struct dentry *dentry = path->dentry;
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);
  	int status;
  
  	DPRINTK("dentry=%p %.*s",
  		dentry, dentry->d_name.len, dentry->d_name.name);
  
  	/* The daemon never triggers a mount. */
  	if (autofs4_oz_mode(sbi))
  		return NULL;
  
  	/*
  	 * If an expire request is pending everyone must wait.
  	 * If the expire fails we're still mounted so continue
  	 * the follow and return. A return of -EAGAIN (which only
  	 * happens with indirect mounts) means the expire completed
  	 * and the directory was removed, so just go ahead and try
  	 * the mount.
  	 */
  	status = do_expire_wait(dentry);
  	if (status && status != -EAGAIN)
  		return NULL;
  
  	/* Callback to the daemon to perform the mount or wait */
  	spin_lock(&sbi->fs_lock);
  	if (ino->flags & AUTOFS_INF_PENDING) {
  		spin_unlock(&sbi->fs_lock);
  		status = autofs4_mount_wait(dentry);
  		if (status)
  			return ERR_PTR(status);
  		spin_lock(&sbi->fs_lock);
  		goto done;
  	}
  
  	/*
  	 * If the dentry is a symlink it's equivalent to a directory

  	 * having d_mountpoint() true, so there's no need to call back

  	 * to the daemon.
  	 */
  	if (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode))
  		goto done;

  	if (!d_mountpoint(dentry)) {
  		/*
  		 * It's possible that user space hasn't removed directories
  		 * after umounting a rootless multi-mount, although it
  		 * should. For v5 have_submounts() is sufficient to handle
  		 * this because the leaves of the directory tree under the
  		 * mount never trigger mounts themselves (they have an autofs
  		 * trigger mount mounted on them). But v4 pseudo direct mounts
  		 * do need the leaves to to trigger mounts. In this case we
  		 * have no choice but to use the list_empty() check and
  		 * require user space behave.
  		 */
  		if (sbi->version > 4) {
  			if (have_submounts(dentry))
  				goto done;
  		} else {
  			spin_lock(&dentry->d_lock);
  			if (!list_empty(&dentry->d_subdirs)) {
  				spin_unlock(&dentry->d_lock);
  				goto done;
  			}
  			spin_unlock(&dentry->d_lock);
  		}

  		ino->flags |= AUTOFS_INF_PENDING;

  		spin_unlock(&sbi->fs_lock);
  		status = autofs4_mount_wait(dentry);
  		if (status)
  			return ERR_PTR(status);
  		spin_lock(&sbi->fs_lock);
  		ino->flags &= ~AUTOFS_INF_PENDING;

  	}

  done:

  	if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
  		/*

  		 * Any needed mounting has been completed and the path
  		 * updated so clear DCACHE_NEED_AUTOMOUNT so we don't
  		 * call ->d_automount() on rootless multi-mounts since
  		 * it can lead to an incorrect ELOOP error return.
  		 *

  		 * Only clear DMANAGED_AUTOMOUNT for rootless multi-mounts and
  		 * symlinks as in all other cases the dentry will be covered by
  		 * an actual mount so ->d_automount() won't be called during
  		 * the follow.
  		 */

  		spin_lock(&dentry->d_lock);

  		if ((!d_mountpoint(dentry) &&
  		    !list_empty(&dentry->d_subdirs)) ||
  		    (dentry->d_inode && S_ISLNK(dentry->d_inode->i_mode)))
  			__managed_dentry_clear_automount(dentry);
  		spin_unlock(&dentry->d_lock);
  	}

  	spin_unlock(&sbi->fs_lock);
  
  	/* Mount succeeded, check if we ended up with a new dentry */
  	dentry = autofs4_mountpoint_changed(path);
  	if (!dentry)
  		return ERR_PTR(-ENOENT);
  
  	return NULL;
  }

  int autofs4_d_manage(struct dentry *dentry, bool rcu_walk)

  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
  
  	DPRINTK("dentry=%p %.*s",
  		dentry, dentry->d_name.len, dentry->d_name.name);
  
  	/* The daemon never waits. */

  	if (autofs4_oz_mode(sbi)) {

  		if (rcu_walk)
  			return 0;

  		if (!d_mountpoint(dentry))
  			return -EISDIR;
  		return 0;
  	}

  	/* We need to sleep, so we need pathwalk to be in ref-mode */
  	if (rcu_walk)
  		return -ECHILD;

  	/* Wait for pending expires */
  	do_expire_wait(dentry);
  
  	/*
  	 * This dentry may be under construction so wait on mount
  	 * completion.
  	 */
  	return autofs4_mount_wait(dentry);
  }

  /* Lookups in the root directory */
  static struct dentry *autofs4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
  {
  	struct autofs_sb_info *sbi;

  	struct autofs_info *ino;

  	struct dentry *active;

  	DPRINTK("name = %.*s", dentry->d_name.len, dentry->d_name.name);

  	/* File name too long to exist */

  	if (dentry->d_name.len > NAME_MAX)

  		return ERR_PTR(-ENAMETOOLONG);

  
  	sbi = autofs4_sbi(dir->i_sb);

  	DPRINTK("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d",

  		current->pid, task_pgrp_nr(current), sbi->catatonic,
  		autofs4_oz_mode(sbi));

  	active = autofs4_lookup_active(dentry);

  	if (active) {

  		return active;

  	} else {

  		/*

  		 * A dentry that is not within the root can never trigger a
  		 * mount operation, unless the directory already exists, so we
  		 * can return fail immediately.  The daemon however does need
  		 * to create directories within the file system.

  		 */

  		if (!autofs4_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
  			return ERR_PTR(-ENOENT);
  
  		/* Mark entries in the root as mount triggers */

  		if (autofs_type_indirect(sbi->type) && IS_ROOT(dentry->d_parent))

  			__managed_dentry_set_managed(dentry);

  		ino = autofs4_new_ino(sbi);

  		if (!ino)
  			return ERR_PTR(-ENOMEM);
  
  		dentry->d_fsdata = ino;
  		ino->dentry = dentry;

  		autofs4_add_active(dentry);
  
  		d_instantiate(dentry, NULL);
  	}

  	return NULL;
  }
  
  static int autofs4_dir_symlink(struct inode *dir, 
  			       struct dentry *dentry,
  			       const char *symname)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);

  	struct autofs_info *p_ino;

  	struct inode *inode;

  	size_t size = strlen(symname);

  	char *cp;
  
  	DPRINTK("%s <- %.*s", symname,
  		dentry->d_name.len, dentry->d_name.name);
  
  	if (!autofs4_oz_mode(sbi))
  		return -EACCES;

  	BUG_ON(!ino);

  	autofs4_clean_ino(ino);

  	autofs4_del_active(dentry);

  	cp = kmalloc(size + 1, GFP_KERNEL);

  	if (!cp)

  		return -ENOMEM;

  
  	strcpy(cp, symname);

  	inode = autofs4_get_inode(dir->i_sb, S_IFLNK | 0555);

  	if (!inode) {
  		kfree(cp);
  		if (!dentry->d_fsdata)
  			kfree(ino);
  		return -ENOMEM;
  	}

  	inode->i_private = cp;

  	inode->i_size = size;

  	d_add(dentry, inode);

  	dget(dentry);

  	atomic_inc(&ino->count);
  	p_ino = autofs4_dentry_ino(dentry->d_parent);
  	if (p_ino && dentry->d_parent != dentry)
  		atomic_inc(&p_ino->count);

  
  	dir->i_mtime = CURRENT_TIME;
  
  	return 0;
  }
  
  /*
   * NOTE!
   *
   * Normal filesystems would do a "d_delete()" to tell the VFS dcache
   * that the file no longer exists. However, doing that means that the
   * VFS layer can turn the dentry into a negative dentry.  We don't want

   * this, because the unlink is probably the result of an expire.

   * We simply d_drop it and add it to a expiring list in the super block,
   * which allows the dentry lookup to check for an incomplete expire.

   *
   * If a process is blocked on the dentry waiting for the expire to finish,
   * it will invalidate the dentry and try to mount with a new one.
   *
   * Also see autofs4_dir_rmdir()..
   */
  static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);

  	struct autofs_info *p_ino;

  	
  	/* This allows root to remove symlinks */

  	if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))

  		return -EACCES;

  	if (atomic_dec_and_test(&ino->count)) {
  		p_ino = autofs4_dentry_ino(dentry->d_parent);
  		if (p_ino && dentry->d_parent != dentry)
  			atomic_dec(&p_ino->count);
  	}

  	dput(ino->dentry);
  
  	dentry->d_inode->i_size = 0;

  	clear_nlink(dentry->d_inode);

  
  	dir->i_mtime = CURRENT_TIME;

  	spin_lock(&sbi->lookup_lock);
  	__autofs4_add_expiring(dentry);

  	spin_lock(&dentry->d_lock);
  	__d_drop(dentry);
  	spin_unlock(&dentry->d_lock);

  	spin_unlock(&sbi->lookup_lock);

  
  	return 0;
  }

  /*
   * Version 4 of autofs provides a pseudo direct mount implementation
   * that relies on directories at the leaves of a directory tree under
   * an indirect mount to trigger mounts. To allow for this we need to
   * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
   * of the directory tree. There is no need to clear the automount flag
   * following a mount or restore it after an expire because these mounts

   * are always covered. However, it is necessary to ensure that these

   * flags are clear on non-empty directories to avoid unnecessary calls
   * during path walks.
   */
  static void autofs_set_leaf_automount_flags(struct dentry *dentry)
  {
  	struct dentry *parent;
  
  	/* root and dentrys in the root are already handled */
  	if (IS_ROOT(dentry->d_parent))
  		return;
  
  	managed_dentry_set_managed(dentry);
  
  	parent = dentry->d_parent;
  	/* only consider parents below dentrys in the root */
  	if (IS_ROOT(parent->d_parent))
  		return;
  	managed_dentry_clear_managed(parent);
  	return;
  }
  
  static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
  {
  	struct list_head *d_child;
  	struct dentry *parent;
  
  	/* flags for dentrys in the root are handled elsewhere */
  	if (IS_ROOT(dentry->d_parent))
  		return;
  
  	managed_dentry_clear_managed(dentry);
  
  	parent = dentry->d_parent;
  	/* only consider parents below dentrys in the root */
  	if (IS_ROOT(parent->d_parent))
  		return;
  	d_child = &dentry->d_u.d_child;
  	/* Set parent managed if it's becoming empty */
  	if (d_child->next == &parent->d_subdirs &&
  	    d_child->prev == &parent->d_subdirs)
  		managed_dentry_set_managed(parent);
  	return;
  }

  static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);

  	struct autofs_info *p_ino;

  	DPRINTK("dentry %p, removing %.*s",
  		dentry, dentry->d_name.len, dentry->d_name.name);

  	if (!autofs4_oz_mode(sbi))
  		return -EACCES;

  	spin_lock(&sbi->lookup_lock);
  	spin_lock(&dentry->d_lock);

  	if (!list_empty(&dentry->d_subdirs)) {

  		spin_unlock(&dentry->d_lock);
  		spin_unlock(&sbi->lookup_lock);

  		return -ENOTEMPTY;
  	}

  	__autofs4_add_expiring(dentry);

  	__d_drop(dentry);
  	spin_unlock(&dentry->d_lock);

  	spin_unlock(&sbi->lookup_lock);

  	if (sbi->version < 5)
  		autofs_clear_leaf_automount_flags(dentry);

  	if (atomic_dec_and_test(&ino->count)) {
  		p_ino = autofs4_dentry_ino(dentry->d_parent);
  		if (p_ino && dentry->d_parent != dentry)
  			atomic_dec(&p_ino->count);
  	}

  	dput(ino->dentry);

  	dentry->d_inode->i_size = 0;

  	clear_nlink(dentry->d_inode);

  
  	if (dir->i_nlink)

  		drop_nlink(dir);

  
  	return 0;
  }

  static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)

  {
  	struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
  	struct autofs_info *ino = autofs4_dentry_ino(dentry);

  	struct autofs_info *p_ino;

  	struct inode *inode;

  	if (!autofs4_oz_mode(sbi))

  		return -EACCES;
  
  	DPRINTK("dentry %p, creating %.*s",
  		dentry, dentry->d_name.len, dentry->d_name.name);

  	BUG_ON(!ino);

  	autofs4_clean_ino(ino);

  	autofs4_del_active(dentry);

  	inode = autofs4_get_inode(dir->i_sb, S_IFDIR | 0555);

  	if (!inode)

  		return -ENOMEM;

  	d_add(dentry, inode);

  	if (sbi->version < 5)
  		autofs_set_leaf_automount_flags(dentry);

  	dget(dentry);

  	atomic_inc(&ino->count);
  	p_ino = autofs4_dentry_ino(dentry->d_parent);
  	if (p_ino && dentry->d_parent != dentry)
  		atomic_inc(&p_ino->count);

  	inc_nlink(dir);

  	dir->i_mtime = CURRENT_TIME;
  
  	return 0;
  }
  
  /* Get/set timeout ioctl() operation */

  #ifdef CONFIG_COMPAT
  static inline int autofs4_compat_get_set_timeout(struct autofs_sb_info *sbi,
  					 compat_ulong_t __user *p)
  {
  	int rv;
  	unsigned long ntimeout;
  
  	if ((rv = get_user(ntimeout, p)) ||
  	     (rv = put_user(sbi->exp_timeout/HZ, p)))
  		return rv;
  
  	if (ntimeout > UINT_MAX/HZ)
  		sbi->exp_timeout = 0;
  	else
  		sbi->exp_timeout = ntimeout * HZ;
  
  	return 0;
  }
  #endif

  static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
  					 unsigned long __user *p)
  {
  	int rv;
  	unsigned long ntimeout;

  	if ((rv = get_user(ntimeout, p)) ||
  	     (rv = put_user(sbi->exp_timeout/HZ, p)))

  		return rv;

  	if (ntimeout > ULONG_MAX/HZ)

  		sbi->exp_timeout = 0;
  	else
  		sbi->exp_timeout = ntimeout * HZ;
  
  	return 0;
  }
  
  /* Return protocol version */
  static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int __user *p)
  {
  	return put_user(sbi->version, p);
  }
  
  /* Return protocol sub version */
  static inline int autofs4_get_protosubver(struct autofs_sb_info *sbi, int __user *p)
  {
  	return put_user(sbi->sub_version, p);
  }
  
  /*

  * Tells the daemon whether it can umount the autofs mount.
  */
  static inline int autofs4_ask_umount(struct vfsmount *mnt, int __user *p)
  {
  	int status = 0;

  	if (may_umount(mnt))

  		status = 1;
  
  	DPRINTK("returning %d", status);
  
  	status = put_user(status, p);
  
  	return status;
  }
  
  /* Identify autofs4_dentries - this is so we can tell if there's
     an extra dentry refcount or not.  We only hold a refcount on the
     dentry if its non-negative (ie, d_inode != NULL)
  */
  int is_autofs4_dentry(struct dentry *dentry)
  {
  	return dentry && dentry->d_inode &&

  		dentry->d_op == &autofs4_dentry_operations &&

  		dentry->d_fsdata != NULL;
  }
  
  /*
   * ioctl()'s on the root directory is the chief method for the daemon to
   * generate kernel reactions
   */

  static int autofs4_root_ioctl_unlocked(struct inode *inode, struct file *filp,
  				       unsigned int cmd, unsigned long arg)

  {
  	struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
  	void __user *p = (void __user *)arg;
  
  	DPRINTK("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u",

  		cmd,arg,sbi,task_pgrp_nr(current));

  	if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
  	     _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)

  		return -ENOTTY;
  	

  	if (!autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))

  		return -EPERM;
  	
  	switch(cmd) {
  	case AUTOFS_IOC_READY:	/* Wait queue: go ahead and retry */
  		return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
  	case AUTOFS_IOC_FAIL:	/* Wait queue: fail with ENOENT */
  		return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
  	case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
  		autofs4_catatonic_mode(sbi);
  		return 0;
  	case AUTOFS_IOC_PROTOVER: /* Get protocol version */
  		return autofs4_get_protover(sbi, p);
  	case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
  		return autofs4_get_protosubver(sbi, p);
  	case AUTOFS_IOC_SETTIMEOUT:
  		return autofs4_get_set_timeout(sbi, p);

  #ifdef CONFIG_COMPAT
  	case AUTOFS_IOC_SETTIMEOUT32:
  		return autofs4_compat_get_set_timeout(sbi, p);
  #endif

  	case AUTOFS_IOC_ASKUMOUNT:

  		return autofs4_ask_umount(filp->f_path.mnt, p);

  
  	/* return a single thing to expire */
  	case AUTOFS_IOC_EXPIRE:

  		return autofs4_expire_run(inode->i_sb,filp->f_path.mnt,sbi, p);

  	/* same as above, but can send multiple expires through pipe */
  	case AUTOFS_IOC_EXPIRE_MULTI:

  		return autofs4_expire_multi(inode->i_sb,filp->f_path.mnt,sbi, p);

  
  	default:
  		return -ENOSYS;
  	}
  }

  
  static long autofs4_root_ioctl(struct file *filp,
  			       unsigned int cmd, unsigned long arg)
  {

  	struct inode *inode = filp->f_dentry->d_inode;

  	return autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);

  }

  
  #ifdef CONFIG_COMPAT
  static long autofs4_root_compat_ioctl(struct file *filp,
  			     unsigned int cmd, unsigned long arg)
  {
  	struct inode *inode = filp->f_path.dentry->d_inode;
  	int ret;

  	if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
  		ret = autofs4_root_ioctl_unlocked(inode, filp, cmd, arg);
  	else
  		ret = autofs4_root_ioctl_unlocked(inode, filp, cmd,
  			(unsigned long)compat_ptr(arg));

  
  	return ret;
  }
  #endif