LXR linux/fs/notify/group.c

   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/list.h>
  20#include <linux/mutex.h>
  21#include <linux/slab.h>
  22#include <linux/srcu.h>
  23#include <linux/rculist.h>
  24#include <linux/wait.h>
  25
  26#include <linux/fsnotify_backend.h>
  27#include "fsnotify.h"
  28
  29#include <linux/atomic.h>
  30
  31/*
  32 * Final freeing of a group
  33 */
  34void fsnotify_final_destroy_group(struct fsnotify_group *group)
  35{
  36        if (group->ops->free_group_priv)
  37                group->ops->free_group_priv(group);
  38
  39        kfree(group);
  40}
  41
  42/*
  43 * Trying to get rid of a group. Remove all marks, flush all events and release
  44 * the group reference.
  45 * Note that another thread calling fsnotify_clear_marks_by_group() may still
  46 * hold a ref to the group.
  47 */
  48void fsnotify_destroy_group(struct fsnotify_group *group)
  49{
  50        /* clear all inode marks for this group */
  51        fsnotify_clear_marks_by_group(group);
  52
  53        synchronize_srcu(&fsnotify_mark_srcu);
  54
  55        /* clear the notification queue of all events */
  56        fsnotify_flush_notify(group);
  57
  58        fsnotify_put_group(group);
  59}
  60
  61/*
  62 * Get reference to a group.
  63 */
  64void fsnotify_get_group(struct fsnotify_group *group)
  65{
  66        atomic_inc(&group->refcnt);
  67}
  68
  69/*
  70 * Drop a reference to a group.  Free it if it's through.
  71 */
  72void fsnotify_put_group(struct fsnotify_group *group)
  73{
  74        if (atomic_dec_and_test(&group->refcnt))
  75                fsnotify_final_destroy_group(group);
  76}
  77
  78/*
  79 * Create a new fsnotify_group and hold a reference for the group returned.
  80 */
  81struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
  82{
  83        struct fsnotify_group *group;
  84
  85        group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
  86        if (!group)
  87                return ERR_PTR(-ENOMEM);
  88
  89        /* set to 0 when there a no external references to this group */
  90        atomic_set(&group->refcnt, 1);
  91        atomic_set(&group->num_marks, 0);
  92
  93        mutex_init(&group->notification_mutex);
  94        INIT_LIST_HEAD(&group->notification_list);
  95        init_waitqueue_head(&group->notification_waitq);
  96        group->max_events = UINT_MAX;
  97
  98        mutex_init(&group->mark_mutex);
  99        INIT_LIST_HEAD(&group->marks_list);
 100
 101        group->ops = ops;
 102
 103        return group;
 104}
 105
 106int fsnotify_fasync(int fd, struct file *file, int on)
 107{
 108        struct fsnotify_group *group = file->private_data;
 109
 110        return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
 111}
 112