Implement a function that can be called when a group is being shutdown
to stop queueing new events to the group. Fanotify will use this.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/notify/group.c | 19 +++++++++++++++++++
fs/notify/notification.c | 5 +++++
include/linux/fsnotify_backend.h | 4 ++++
3 files changed, 28 insertions(+)
diff --git a/fs/notify/group.c b/fs/notify/group.c
index 3e2dd85be5dd..b47f7cfdcaa4 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -40,6 +40,17 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *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)
+{
+ mutex_lock(&group->notification_mutex);
+ group->shutdown = true;
+ mutex_unlock(&group->notification_mutex);
+}
+
+/*
* 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
@@ -47,6 +58,14 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *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 inode marks for this group, attach them to destroy_list */
fsnotify_detach_group_marks(group);
diff --git a/fs/notify/notification.c b/fs/notify/notification.c
index 12bfd6790fc4..af0497cac06c 100644
--- a/fs/notify/notification.c
+++ b/fs/notify/notification.c
@@ -96,6 +96,11 @@ enum fsn_add_event_ret fsnotify_add_event(
mutex_lock(&group->notification_mutex);
+ if (group->shutdown) {
+ mutex_unlock(&group->notification_mutex);
+ return AE_SHUTDOWN;
+ }
+
if (group->q_len >= group->max_events) {
ret = AE_OVERFLOW;
/* Queue overflow event only if it isn't already queued */
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index b948a52ce65f..bcba826a99fc 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -148,6 +148,7 @@ struct fsnotify_group {
#define FS_PRIO_1 1 /* fanotify content based access control */
#define FS_PRIO_2 2 /* fanotify pre-content access */
unsigned int priority;
+ bool shutdown; /* group is being shut down, don't queue more events */
/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
struct mutex mark_mutex; /* protect marks_list */
@@ -292,6 +293,8 @@ extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *op
extern void fsnotify_get_group(struct fsnotify_group *group);
/* drop reference on a group from fsnotify_alloc_group */
extern void fsnotify_put_group(struct fsnotify_group *group);
+/* group destruction begins, stop queuing new events */
+extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
/* destroy group */
extern void fsnotify_destroy_group(struct fsnotify_group *group);
/* fasync handler function */
@@ -304,6 +307,7 @@ enum fsn_add_event_ret {
AE_INSERTED, /* Event was added in the queue */
AE_MERGED, /* Event was merged with another event, passed event unused */
AE_OVERFLOW, /* Queue overflow, passed event unused */
+ AE_SHUTDOWN, /* Group is being released, passed event unused */
};
/* attach the event to the group notification queue */
extern enum fsn_add_event_ret fsnotify_add_event(
--
2.6.6
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