105 lines
3.0 KiB
C
105 lines
3.0 KiB
C
/*
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/srcu.h>
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#include <linux/rculist.h>
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#include <linux/wait.h>
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#include <linux/fsnotify_backend.h>
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#include "fsnotify.h"
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#include <asm/atomic.h>
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/*
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* Final freeing of a group
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*/
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void fsnotify_final_destroy_group(struct fsnotify_group *group)
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{
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/* clear the notification queue of all events */
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fsnotify_flush_notify(group);
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if (group->ops->free_group_priv)
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group->ops->free_group_priv(group);
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kfree(group);
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}
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/*
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* Trying to get rid of a group. We need to first get rid of any outstanding
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* allocations and then free the group. Remember that fsnotify_clear_marks_by_group
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* could miss marks that are being freed by inode and those marks could still
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* hold a reference to this group (via group->num_marks) If we get into that
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* situtation, the fsnotify_final_destroy_group will get called when that final
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* mark is freed.
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*/
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static void fsnotify_destroy_group(struct fsnotify_group *group)
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{
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/* clear all inode marks for this group */
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fsnotify_clear_marks_by_group(group);
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synchronize_srcu(&fsnotify_mark_srcu);
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/* past the point of no return, matches the initial value of 1 */
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if (atomic_dec_and_test(&group->num_marks))
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fsnotify_final_destroy_group(group);
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}
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/*
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* Drop a reference to a group. Free it if it's through.
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*/
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void fsnotify_put_group(struct fsnotify_group *group)
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{
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if (atomic_dec_and_test(&group->refcnt))
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fsnotify_destroy_group(group);
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}
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/*
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* Create a new fsnotify_group and hold a reference for the group returned.
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*/
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struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
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{
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struct fsnotify_group *group;
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group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
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if (!group)
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return ERR_PTR(-ENOMEM);
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/* set to 0 when there a no external references to this group */
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atomic_set(&group->refcnt, 1);
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/*
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* hits 0 when there are no external references AND no marks for
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* this group
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*/
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atomic_set(&group->num_marks, 1);
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mutex_init(&group->notification_mutex);
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INIT_LIST_HEAD(&group->notification_list);
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init_waitqueue_head(&group->notification_waitq);
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group->max_events = UINT_MAX;
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spin_lock_init(&group->mark_lock);
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INIT_LIST_HEAD(&group->marks_list);
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group->ops = ops;
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return group;
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}
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