Btrfs: qgroup implementation and prototypes

Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 23cbda0..0d6c881 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -351,6 +351,8 @@
 	h->block_rsv = NULL;
 	h->orig_rsv = NULL;
 	h->aborted = 0;
+	h->delayed_ref_elem.seq = 0;
+	INIT_LIST_HEAD(&h->qgroup_ref_list);
 
 	smp_mb();
 	if (cur_trans->blocked && may_wait_transaction(root, type)) {