fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called

Currently fsnotify check is mark->group is NULL to decide if
fsnotify_destroy_mark() has already been called or not.  With the upcoming
rcu work it is a heck of a lot easier to use an explicit flag than worry
about group being set to NULL.

Signed-off-by: Eric Paris <eparis@redhat.com>

3 files changed, 9 insertions, 6 deletions

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 455cb41c729b..37b460f302b7 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -187,7 +187,7 @@ int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
         struct hlist_node *node, *last = NULL;
         int ret = 0;
 
-        mark->flags = FSNOTIFY_MARK_FLAG_INODE;
+        mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
 
         assert_spin_locked(&mark->lock);
         assert_spin_locked(&group->mark_lock);
diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index 8f3b0e7a543d..69c5a166930c 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -121,12 +121,14 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
 
         group = mark->group;
 
-        /* if !group something else already marked this to die */
-        if (!group) {
+        /* something else already called this function on this mark */
+        if (!(mark->flags & FSNOTIFY_MARK_FLAG_ALIVE)) {
                 spin_unlock(&mark->lock);
                 return;
         }
 
+        mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE;
+
         /* 1 from caller and 1 for being on i_list/g_list */
         BUG_ON(atomic_read(&mark->refcnt) < 2);
 
@@ -141,7 +143,6 @@ void fsnotify_destroy_mark(struct fsnotify_mark *mark)
                 BUG();
 
         list_del_init(&mark->g_list);
-        mark->group = NULL;
 
         fsnotify_put_mark(mark); /* for i_list and g_list */
 
@@ -229,6 +230,8 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
         spin_lock(&mark->lock);
         spin_lock(&group->mark_lock);
 
+        mark->flags |= FSNOTIFY_MARK_FLAG_ALIVE;
+
         mark->group = group;
         list_add(&mark->g_list, &group->marks_list);
         atomic_inc(&group->num_marks);
@@ -258,7 +261,7 @@ int fsnotify_add_mark(struct fsnotify_mark *mark,
 
         return ret;
 err:
-        mark->group = NULL;
+        mark->flags &= ~FSNOTIFY_MARK_FLAG_ALIVE;
         list_del_init(&mark->g_list);
         atomic_dec(&group->num_marks);
         fsnotify_put_mark(mark);
diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c
index b7ae64030021..56772b578fbd 100644
--- a/fs/notify/vfsmount_mark.c
+++ b/fs/notify/vfsmount_mark.c
@@ -145,7 +145,7 @@ int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
         struct hlist_node *node, *last = NULL;
         int ret = 0;
 
-        mark->flags = FSNOTIFY_MARK_FLAG_VFSMOUNT;
+        mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
 
         assert_spin_locked(&mark->lock);
         assert_spin_locked(&group->mark_lock);