/* mountpoint management

   *
   * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/fs.h>
  #include <linux/pagemap.h>
  #include <linux/mount.h>
  #include <linux/namei.h>

  #include <linux/gfp.h>

  #include "internal.h"
  
  
  static struct dentry *afs_mntpt_lookup(struct inode *dir,
  				       struct dentry *dentry,

  				       unsigned int flags);

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

  static void afs_mntpt_expiry_timed_out(struct work_struct *work);

  const struct file_operations afs_mntpt_file_operations = {

  	.open		= afs_mntpt_open,

  	.llseek		= noop_llseek,

  };

  const struct inode_operations afs_mntpt_inode_operations = {

  	.lookup		= afs_mntpt_lookup,

  	.readlink	= page_readlink,

  	.getattr	= afs_getattr,

  	.listxattr	= afs_listxattr,

  };

  const struct inode_operations afs_autocell_inode_operations = {

  	.getattr	= afs_getattr,
  };

  static LIST_HEAD(afs_vfsmounts);

  static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out);

  static unsigned long afs_mntpt_expiry_timeout = 10 * 60;

  /*

   * no valid lookup procedure on this sort of dir
   */
  static struct dentry *afs_mntpt_lookup(struct inode *dir,
  				       struct dentry *dentry,

  				       unsigned int flags)

  {

  	_enter("%p,%p{%pd2}", dir, dentry, dentry);

  	return ERR_PTR(-EREMOTE);

  }

  /*
   * no valid open procedure on this sort of dir
   */
  static int afs_mntpt_open(struct inode *inode, struct file *file)
  {

  	_enter("%p,%p{%pD2}", inode, file, file);

  	return -EREMOTE;

  }

  /*
   * create a vfsmount to be automounted
   */
  static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt)
  {
  	struct afs_super_info *super;
  	struct vfsmount *mnt;

  	struct afs_vnode *vnode;

  	struct page *page;

  	char *devname, *options;
  	bool rwpath = false;

  	int ret;

  	_enter("{%pd}", mntpt);

  	BUG_ON(!d_inode(mntpt));

  	ret = -ENOMEM;
  	devname = (char *) get_zeroed_page(GFP_KERNEL);
  	if (!devname)

  		goto error_no_devname;

  
  	options = (char *) get_zeroed_page(GFP_KERNEL);
  	if (!options)

  		goto error_no_options;

  	vnode = AFS_FS_I(d_inode(mntpt));

  	if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
  		/* if the directory is a pseudo directory, use the d_name */
  		static const char afs_root_cell[] = ":root.cell.";
  		unsigned size = mntpt->d_name.len;
  
  		ret = -ENOENT;
  		if (size < 2 || size > AFS_MAXCELLNAME)
  			goto error_no_page;
  
  		if (mntpt->d_name.name[0] == '.') {
  			devname[0] = '#';
  			memcpy(devname + 1, mntpt->d_name.name, size - 1);
  			memcpy(devname + size, afs_root_cell,
  			       sizeof(afs_root_cell));
  			rwpath = true;
  		} else {
  			devname[0] = '%';
  			memcpy(devname + 1, mntpt->d_name.name, size);
  			memcpy(devname + size + 1, afs_root_cell,
  			       sizeof(afs_root_cell));
  		}
  	} else {
  		/* read the contents of the AFS special symlink */

  		loff_t size = i_size_read(d_inode(mntpt));

  		char *buf;
  
  		ret = -EINVAL;
  		if (size > PAGE_SIZE - 1)
  			goto error_no_page;

  		page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);

  		if (IS_ERR(page)) {
  			ret = PTR_ERR(page);
  			goto error_no_page;
  		}
  
  		ret = -EIO;
  		if (PageError(page))
  			goto error;

  		buf = kmap_atomic(page);

  		memcpy(devname, buf, size);

  		kunmap_atomic(buf);

  		put_page(page);

  		page = NULL;

  	}

  	/* work out what options we want */
  	super = AFS_FS_S(mntpt->d_sb);
  	memcpy(options, "cell=", 5);
  	strcpy(options + 5, super->volume->cell->name);

  	if (super->volume->type == AFSVL_RWVOL || rwpath)

  		strcat(options, ",rwpath");
  
  	/* try and do the mount */

  	_debug("--- attempting mount %s -o %s ---", devname, options);

  	mnt = vfs_submount(mntpt, &afs_fs_type, devname, options);

  	_debug("--- mount result %p ---", mnt);

  
  	free_page((unsigned long) devname);
  	free_page((unsigned long) options);

  	_leave(" = %p", mnt);

  	return mnt;

  error:

  	put_page(page);

  error_no_page:
  	free_page((unsigned long) options);
  error_no_options:
  	free_page((unsigned long) devname);
  error_no_devname:

  	_leave(" = %d", ret);

  	return ERR_PTR(ret);

  }

  /*

   * handle an automount point

   */

  struct vfsmount *afs_d_automount(struct path *path)

  {
  	struct vfsmount *newmnt;

  	_enter("{%pd}", path->dentry);

  	newmnt = afs_mntpt_do_automount(path->dentry);
  	if (IS_ERR(newmnt))
  		return newmnt;

  	mntget(newmnt); /* prevent immediate expiration */
  	mnt_set_expiry(newmnt, &afs_vfsmounts);
  	queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
  			   afs_mntpt_expiry_timeout * HZ);

  	_leave(" = %p", newmnt);

  	return newmnt;

  }

  /*
   * handle mountpoint expiry timer going off
   */

  static void afs_mntpt_expiry_timed_out(struct work_struct *work)

  {

  	_enter("");
  
  	if (!list_empty(&afs_vfsmounts)) {
  		mark_mounts_for_expiry(&afs_vfsmounts);

  		queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer,
  				   afs_mntpt_expiry_timeout * HZ);

  	}
  
  	_leave("");
  }

  /*
   * kill the AFS mountpoint timer if it's still running
   */
  void afs_mntpt_kill_timer(void)
  {
  	_enter("");

  	ASSERT(list_empty(&afs_vfsmounts));

  	cancel_delayed_work_sync(&afs_mntpt_expiry_timer);

  }