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>

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 455cb41..37b460f 100644 (file)
--- 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 8f3b0e7..69c5a16 100644 (file)
--- 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 b7ae640..56772b5 100644 (file)
--- 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);

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 3410d38..8e24cdf 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -300,6 +300,7 @@ struct fsnotify_mark {
 #define FSNOTIFY_MARK_FLAG_VFSMOUNT            0x02
 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED       0x04
 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
+#define FSNOTIFY_MARK_FLAG_ALIVE               0x10
        unsigned int flags;             /* vfsmount or inode mark? */
        void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
 };