Btrfs: use RB_ROOT to intialize rb_trees instead of setting rb_node to NULL

btrfs inialize rb trees in quite a number of places by settin rb_node =
NULL;  The problem with this is that 17d9ddc72fb8bba0d4f678 in the
linux-next tree adds a new field to that struct which needs to be NULL for
the new rbtree library code to work properly.  This patch uses RB_ROOT as
the intializer so all of the relevant fields will be NULL'd.  Without the
patch I get a panic.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/ref-cache.h b/fs/btrfs/ref-cache.h
index bc283ad2db73..e2a55cb2072b 100644
--- a/fs/btrfs/ref-cache.h
+++ b/fs/btrfs/ref-cache.h
@@ -52,7 +52,7 @@ static inline size_t btrfs_leaf_ref_size(int nr_extents)
 
 static inline void btrfs_leaf_ref_tree_init(struct btrfs_leaf_ref_tree *tree)
 {
-        tree->root.rb_node = NULL;
+        tree->root = RB_ROOT;
         INIT_LIST_HEAD(&tree->list);
         spin_lock_init(&tree->lock);
 }