1/*
  2 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
  3 *
  4 *  This program is free software; you can redistribute it and/or modify
  5 *  it under the terms of the GNU General Public License as published by
  6 *  the Free Software Foundation; either version 2, or (at your option)
  7 *  any later version.
  8 *
  9 *  This program is distributed in the hope that it will be useful,
 10 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 11 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12 *  GNU General Public License for more details.
 13 *
 14 *  You should have received a copy of the GNU General Public License
 15 *  along with this program; see the file COPYING.  If not, write to
 16 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 17 */
 18
 19#include <linux/fs.h>
 20#include <linux/init.h>
 21#include <linux/kernel.h>
 22#include <linux/module.h>
 23#include <linux/mount.h>
 24#include <linux/mutex.h>
 25#include <linux/spinlock.h>
 26
 27#include <linux/atomic.h>
 28
 29#include <linux/fsnotify_backend.h>
 30#include "fsnotify.h"
 31
 32void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
 33{
 34	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
 35}
 36
 37/*
 38 * Recalculate the mnt->mnt_fsnotify_mask, or the mask of all FS_* event types
 39 * any notifier is interested in hearing for this mount point
 40 */
 41void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
 42{
 43	struct mount *m = real_mount(mnt);
 44
 45	spin_lock(&mnt->mnt_root->d_lock);
 46	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
 47	spin_unlock(&mnt->mnt_root->d_lock);
 48}
 49
 50void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
 51{
 52	struct vfsmount *mnt = mark->mnt;
 53	struct mount *m = real_mount(mnt);
 54
 55	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
 56	assert_spin_locked(&mark->lock);
 57
 58	spin_lock(&mnt->mnt_root->d_lock);
 59
 60	hlist_del_init_rcu(&mark->obj_list);
 61	mark->mnt = NULL;
 62
 63	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
 64	spin_unlock(&mnt->mnt_root->d_lock);
 65}
 66
 67/*
 68 * given a group and vfsmount, find the mark associated with that combination.
 69 * if found take a reference to that mark and return it, else return NULL
 70 */
 71struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group,
 72						  struct vfsmount *mnt)
 73{
 74	struct mount *m = real_mount(mnt);
 75	struct fsnotify_mark *mark;
 76
 77	spin_lock(&mnt->mnt_root->d_lock);
 78	mark = fsnotify_find_mark(&m->mnt_fsnotify_marks, group);
 79	spin_unlock(&mnt->mnt_root->d_lock);
 80
 81	return mark;
 82}
 83
 84/*
 85 * Attach an initialized mark to a given group and vfsmount.
 86 * These marks may be used for the fsnotify backend to determine which
 87 * event types should be delivered to which groups.
 88 */
 89int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
 90			       struct fsnotify_group *group, struct vfsmount *mnt,
 91			       int allow_dups)
 92{
 93	struct mount *m = real_mount(mnt);
 94	int ret;
 95
 96	mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
 97
 98	BUG_ON(!mutex_is_locked(&group->mark_mutex));
 99	assert_spin_locked(&mark->lock);
100
101	spin_lock(&mnt->mnt_root->d_lock);
102	mark->mnt = mnt;
103	ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, allow_dups);
104	m->mnt_fsnotify_mask = fsnotify_recalc_mask(&m->mnt_fsnotify_marks);
105	spin_unlock(&mnt->mnt_root->d_lock);
106
107	return ret;
108}