1 // SPDX-License-Identifier: GPL-2.0-or-later
9  * the event happened.  When inotify gets an event it will need to add that
10  * event to the group notify queue.  Since a single event might need to be on
11  * multiple group's notification queues we can't add the event directly to each
13  * has a pointer back to the original event.  Since the majority of events are
15  * event_holder into each event.  This means we have a single allocation instead
41  * fsnotify_get_cookie - return a unique cookie for use in synchronizing events.
51 			    struct fsnotify_event *event)  in fsnotify_destroy_event()  argument
53 	/* Overflow events are per-group and we don't want to free them */  in fsnotify_destroy_event()
54 	if (!event || event == group->overflow_event)  in fsnotify_destroy_event()
57 	 * If the event is still queued, we have a problem... Do an unreliable  in fsnotify_destroy_event()
60 	 * from the list by a different CPU than the one freeing the event.  in fsnotify_destroy_event()
62 	if (!list_empty(&event->list)) {  in fsnotify_destroy_event()
63 		spin_lock(&group->notification_lock);  in fsnotify_destroy_event()
64 		WARN_ON(!list_empty(&event->list));  in fsnotify_destroy_event()
65 		spin_unlock(&group->notification_lock);  in fsnotify_destroy_event()
67 	group->ops->free_event(group, event);  in fsnotify_destroy_event()
71  * Try to add an event to the notification queue.
72  * The group can later pull this event off the queue to deal with.
73  * The group can use the @merge hook to merge the event with a queued event.
74  * The group can use the @insert hook to insert the event into hash table.
76  * 0 if the event was added to a queue
77  * 1 if the event was merged with some other queued event
78  * 2 if the event was not queued - either the queue of events has overflown
82 			  struct fsnotify_event *event,  in fsnotify_insert_event()  argument
89 	struct list_head *list = &group->notification_list;  in fsnotify_insert_event()
91 	pr_debug("%s: group=%p event=%p\n", __func__, group, event);  in fsnotify_insert_event()
93 	spin_lock(&group->notification_lock);  in fsnotify_insert_event()
95 	if (group->shutdown) {  in fsnotify_insert_event()
96 		spin_unlock(&group->notification_lock);  in fsnotify_insert_event()
100 	if (event == group->overflow_event ||  in fsnotify_insert_event()
101 	    group->q_len >= group->max_events) {  in fsnotify_insert_event()
103 		/* Queue overflow event only if it isn't already queued */  in fsnotify_insert_event()
104 		if (!list_empty(&group->overflow_event->list)) {  in fsnotify_insert_event()
105 			spin_unlock(&group->notification_lock);  in fsnotify_insert_event()
108 		event = group->overflow_event;  in fsnotify_insert_event()
113 		ret = merge(group, event);  in fsnotify_insert_event()
115 			spin_unlock(&group->notification_lock);  in fsnotify_insert_event()
121 	group->q_len++;  in fsnotify_insert_event()
122 	list_add_tail(&event->list, list);  in fsnotify_insert_event()
124 		insert(group, event);  in fsnotify_insert_event()
125 	spin_unlock(&group->notification_lock);  in fsnotify_insert_event()
127 	wake_up(&group->notification_waitq);  in fsnotify_insert_event()
128 	kill_fasync(&group->fsn_fa, SIGIO, POLL_IN);  in fsnotify_insert_event()
133 				  struct fsnotify_event *event)  in fsnotify_remove_queued_event()  argument
135 	assert_spin_locked(&group->notification_lock);  in fsnotify_remove_queued_event()
137 	 * We need to init list head for the case of overflow event so that  in fsnotify_remove_queued_event()
140 	list_del_init(&event->list);  in fsnotify_remove_queued_event()
141 	group->q_len--;  in fsnotify_remove_queued_event()
145  * Return the first event on the notification list without removing it.
150 	assert_spin_locked(&group->notification_lock);  in fsnotify_peek_first_event()
155 	return list_first_entry(&group->notification_list,  in fsnotify_peek_first_event()
160  * Remove and return the first event from the notification list.  It is the
161  * responsibility of the caller to destroy the obtained event
165 	struct fsnotify_event *event = fsnotify_peek_first_event(group);  in fsnotify_remove_first_event()  local
167 	if (!event)  in fsnotify_remove_first_event()
170 	pr_debug("%s: group=%p event=%p\n", __func__, group, event);  in fsnotify_remove_first_event()
172 	fsnotify_remove_queued_event(group, event);  in fsnotify_remove_first_event()
174 	return event;  in fsnotify_remove_first_event()
179  * event notifications.
183 	struct fsnotify_event *event;  in fsnotify_flush_notify()  local
185 	spin_lock(&group->notification_lock);  in fsnotify_flush_notify()
187 		event = fsnotify_remove_first_event(group);  in fsnotify_flush_notify()
188 		spin_unlock(&group->notification_lock);  in fsnotify_flush_notify()
189 		fsnotify_destroy_event(group, event);  in fsnotify_flush_notify()
190 		spin_lock(&group->notification_lock);  in fsnotify_flush_notify()
192 	spin_unlock(&group->notification_lock);  in fsnotify_flush_notify()