fs/notify/group.c

Source file repositories/reference/linux-study-clean/fs/notify/group.c

File Facts

System
Linux kernel
Corpus path
fs/notify/group.c
Extension
.c
Size
4385 bytes
Lines
161
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
 */

#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/memcontrol.h>

#include <linux/fsnotify_backend.h>
#include "fsnotify.h"

#include <linux/atomic.h>

/*
 * Final freeing of a group
 */
static void fsnotify_final_destroy_group(struct fsnotify_group *group)
{
	if (group->ops->free_group_priv)
		group->ops->free_group_priv(group);

	mem_cgroup_put(group->memcg);
	mutex_destroy(&group->mark_mutex);

	kfree(group);
}

/*
 * Stop queueing new events for this group. Once this function returns
 * fsnotify_add_event() will not add any new events to the group's queue.
 */
void fsnotify_group_stop_queueing(struct fsnotify_group *group)
{
	spin_lock(&group->notification_lock);
	group->shutdown = true;
	spin_unlock(&group->notification_lock);
}

/*
 * Trying to get rid of a group. Remove all marks, flush all events and release
 * the group reference.
 * Note that another thread calling fsnotify_clear_marks_by_group() may still
 * hold a ref to the group.
 */
void fsnotify_destroy_group(struct fsnotify_group *group)
{
	/*
	 * Stop queueing new events. The code below is careful enough to not
	 * require this but fanotify needs to stop queuing events even before
	 * fsnotify_destroy_group() is called and this makes the other callers
	 * of fsnotify_destroy_group() to see the same behavior.
	 */
	fsnotify_group_stop_queueing(group);

	/* Clear all marks for this group and queue them for destruction */
	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_ANY);

	/*
	 * Some marks can still be pinned when waiting for response from
	 * userspace. Wait for those now. fsnotify_prepare_user_wait() will
	 * not succeed now so this wait is race-free.
	 */
	wait_event(group->notification_waitq, !atomic_read(&group->user_waits));

	/*
	 * Wait until all marks get really destroyed. We could actually destroy
	 * them ourselves instead of waiting for worker to do it, however that
	 * would be racy as worker can already be processing some marks before
	 * we even entered fsnotify_destroy_group().
	 */
	fsnotify_wait_marks_destroyed();

	/*
	 * Since we have waited for fsnotify_mark_srcu in
	 * fsnotify_mark_destroy_list() there can be no outstanding event
	 * notification against this group. So clearing the notification queue
	 * of all events is reliable now.
	 */
	fsnotify_flush_notify(group);

	/*
	 * Destroy overflow event (we cannot use fsnotify_destroy_event() as
	 * that deliberately ignores overflow events.
	 */
	if (group->overflow_event)

Annotation

Implementation Notes