Btrfs: Use a chunk of the key flags to record the item type.
Add (untested and simple) directory item code
Fix comp_keys to use the new key ordering
Add btrfs_insert_empty_item

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 03aa7c2..a24b472 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -27,7 +27,7 @@
 	l = &path.nodes[0]->leaf;
 	BUG_ON(path.slots[0] == 0);
 	slot = path.slots[0] - 1;
-	if (btrfs_key_objectid(&l->items[slot].key) != objectid) {
+	if (btrfs_disk_key_objectid(&l->items[slot].key) != objectid) {
 		ret = 1;
 		goto out;
 	}