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02436668d9
The global fsnotify groups lists were invented as a way to increase the performance of fsnotify by shortcutting events which were not interesting. With the changes to walk the object lists rather than global groups lists these shortcuts are not useful. Signed-off-by: Eric Paris <eparis@redhat.com>
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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