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-rw-r--r--fs/notify/mark.c30
1 files changed, 25 insertions, 5 deletions
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 92e48c70f0f0..39ddcaf0918f 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -412,16 +412,36 @@ void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group,
unsigned int flags)
{
struct fsnotify_mark *lmark, *mark;
+ LIST_HEAD(to_free);
+ /*
+ * We have to be really careful here. Anytime we drop mark_mutex, e.g.
+ * fsnotify_clear_marks_by_inode() can come and free marks. Even in our
+ * to_free list so we have to use mark_mutex even when accessing that
+ * list. And freeing mark requires us to drop mark_mutex. So we can
+ * reliably free only the first mark in the list. That's why we first
+ * move marks to free to to_free list in one go and then free marks in
+ * to_free list one by one.
+ */
mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
- if (mark->flags & flags) {
- fsnotify_get_mark(mark);
- fsnotify_destroy_mark_locked(mark, group);
- fsnotify_put_mark(mark);
- }
+ if (mark->flags & flags)
+ list_move(&mark->g_list, &to_free);
}
mutex_unlock(&group->mark_mutex);
+
+ while (1) {
+ mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
+ if (list_empty(&to_free)) {
+ mutex_unlock(&group->mark_mutex);
+ break;
+ }
+ mark = list_first_entry(&to_free, struct fsnotify_mark, g_list);
+ fsnotify_get_mark(mark);
+ fsnotify_destroy_mark_locked(mark, group);
+ mutex_unlock(&group->mark_mutex);
+ fsnotify_put_mark(mark);
+ }
}
/*