/* * 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/list.h> #include <linux/mutex.h> #include <linux/slab.h> #include <linux/srcu.h> #include <linux/rculist.h> #include <linux/wait.h> #include <linux/fsnotify_backend.h> #include "fsnotify.h" #include <asm/atomic.h> /* * Final freeing of a group */ void fsnotify_final_destroy_group(struct fsnotify_group *group) { /* clear the notification queue of all events */ fsnotify_flush_notify(group); if (group->ops->free_group_priv) group->ops->free_group_priv(group); kfree(group); } /* * Trying to get rid of a group. We need to first get rid of any outstanding * allocations and then free the group. Remember that fsnotify_clear_marks_by_group * could miss marks that are being freed by inode and those marks could still * hold a reference to this group (via group->num_marks) If we get into that * situtation, the fsnotify_final_destroy_group will get called when that final * mark is freed. */ static void fsnotify_destroy_group(struct fsnotify_group *group) { /* clear all inode marks for this group */ fsnotify_clear_marks_by_group(group); synchronize_srcu(&fsnotify_mark_srcu); /* past the point of no return, matches the initial value of 1 */ if (atomic_dec_and_test(&group->num_marks)) fsnotify_final_destroy_group(group); } /* * Drop a reference to a group. Free it if it's through. */ void fsnotify_put_group(struct fsnotify_group *group) { if (atomic_dec_and_test(&group->refcnt)) fsnotify_destroy_group(group); } /* * Create a new fsnotify_group and hold a reference for the group returned. */ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) { struct fsnotify_group *group; group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); if (!group) return ERR_PTR(-ENOMEM); /* set to 0 when there a no external references to this group */ atomic_set(&group->refcnt, 1); /* * hits 0 when there are no external references AND no marks for * this group */ atomic_set(&group->num_marks, 1); mutex_init(&group->notification_mutex); INIT_LIST_HEAD(&group->notification_list); init_waitqueue_head(&group->notification_waitq); group->max_events = UINT_MAX; spin_lock_init(&group->mark_lock); INIT_LIST_HEAD(&group->marks_list); group->ops = ops; return group; }