/*
   *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@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, or (at your option)
   *  any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; see the file COPYING.  If not, write to
   *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/fs.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/mount.h>
  #include <linux/mutex.h>

  #include <linux/spinlock.h>

  #include <linux/atomic.h>

  
  #include <linux/fsnotify_backend.h>
  #include "fsnotify.h"
  
  void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
  {
  	struct fsnotify_mark *mark, *lmark;
  	struct hlist_node *pos, *n;
  	LIST_HEAD(free_list);
  
  	spin_lock(&mnt->mnt_root->d_lock);
  	hlist_for_each_entry_safe(mark, pos, n, &mnt->mnt_fsnotify_marks, m.m_list) {
  		list_add(&mark->m.free_m_list, &free_list);

  		hlist_del_init_rcu(&mark->m.m_list);

  		fsnotify_get_mark(mark);
  	}
  	spin_unlock(&mnt->mnt_root->d_lock);
  
  	list_for_each_entry_safe(mark, lmark, &free_list, m.free_m_list) {
  		fsnotify_destroy_mark(mark);
  		fsnotify_put_mark(mark);
  	}
  }

  void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
  {
  	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
  }

  /*
   * Recalculate the mask of events relevant to a given vfsmount locked.
   */
  static void fsnotify_recalc_vfsmount_mask_locked(struct vfsmount *mnt)
  {
  	struct fsnotify_mark *mark;
  	struct hlist_node *pos;
  	__u32 new_mask = 0;
  
  	assert_spin_locked(&mnt->mnt_root->d_lock);
  
  	hlist_for_each_entry(mark, pos, &mnt->mnt_fsnotify_marks, m.m_list)
  		new_mask |= mark->mask;
  	mnt->mnt_fsnotify_mask = new_mask;
  }
  
  /*
   * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
   * any notifier is interested in hearing for this mount point
   */
  void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
  {
  	spin_lock(&mnt->mnt_root->d_lock);
  	fsnotify_recalc_vfsmount_mask_locked(mnt);
  	spin_unlock(&mnt->mnt_root->d_lock);
  }
  
  void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
  {
  	struct vfsmount *mnt = mark->m.mnt;
  
  	assert_spin_locked(&mark->lock);
  	assert_spin_locked(&mark->group->mark_lock);
  
  	spin_lock(&mnt->mnt_root->d_lock);

  	hlist_del_init_rcu(&mark->m.m_list);

  	mark->m.mnt = NULL;
  
  	fsnotify_recalc_vfsmount_mask_locked(mnt);
  
  	spin_unlock(&mnt->mnt_root->d_lock);
  }
  
  static struct fsnotify_mark *fsnotify_find_vfsmount_mark_locked(struct fsnotify_group *group,
  								struct vfsmount *mnt)
  {
  	struct fsnotify_mark *mark;
  	struct hlist_node *pos;
  
  	assert_spin_locked(&mnt->mnt_root->d_lock);
  
  	hlist_for_each_entry(mark, pos, &mnt->mnt_fsnotify_marks, m.m_list) {
  		if (mark->group == group) {
  			fsnotify_get_mark(mark);
  			return mark;
  		}
  	}
  	return NULL;
  }
  
  /*
   * given a group and vfsmount, find the mark associated with that combination.
   * if found take a reference to that mark and return it, else return NULL
   */
  struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
  						  struct vfsmount *mnt)
  {
  	struct fsnotify_mark *mark;
  
  	spin_lock(&mnt->mnt_root->d_lock);
  	mark = fsnotify_find_vfsmount_mark_locked(group, mnt);
  	spin_unlock(&mnt->mnt_root->d_lock);
  
  	return mark;
  }
  
  /*
   * Attach an initialized mark to a given group and vfsmount.
   * These marks may be used for the fsnotify backend to determine which
   * event types should be delivered to which groups.
   */
  int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
  			       struct fsnotify_group *group, struct vfsmount *mnt,
  			       int allow_dups)
  {

  	struct fsnotify_mark *lmark;
  	struct hlist_node *node, *last = NULL;

  	int ret = 0;

  	mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;

  	assert_spin_locked(&mark->lock);
  	assert_spin_locked(&group->mark_lock);
  
  	spin_lock(&mnt->mnt_root->d_lock);

  	mark->m.mnt = mnt;

  	/* is mark the first mark? */
  	if (hlist_empty(&mnt->mnt_fsnotify_marks)) {

  		hlist_add_head_rcu(&mark->m.m_list, &mnt->mnt_fsnotify_marks);

  		goto out;
  	}
  
  	/* should mark be in the middle of the current list? */
  	hlist_for_each_entry(lmark, node, &mnt->mnt_fsnotify_marks, m.m_list) {
  		last = node;
  
  		if ((lmark->group == group) && !allow_dups) {
  			ret = -EEXIST;
  			goto out;
  		}

  		if (mark->group->priority < lmark->group->priority)
  			continue;
  
  		if ((mark->group->priority == lmark->group->priority) &&
  		    (mark->group < lmark->group))

  			continue;

  		hlist_add_before_rcu(&mark->m.m_list, &lmark->m.m_list);

  		goto out;

  	}

  	BUG_ON(last == NULL);
  	/* mark should be the last entry.  last is the current last entry */

  	hlist_add_after_rcu(last, &mark->m.m_list);

  out:
  	fsnotify_recalc_vfsmount_mask_locked(mnt);

  	spin_unlock(&mnt->mnt_root->d_lock);
  
  	return ret;
  }