btrfs-progs: add orphan support to print-tree

This adds orphan support to print-tree so when debug_tree hits an orphan item it
will print out "orphan item" under it so you know what it is

ctree.h

@@ -55,6 +55,9 @@ struct btrfs_trans_handle;
 /* directory objectid inside the root tree */
 #define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
 
+/* oprhan objectid for tracking unlinked/truncated files */
+#define BTRFS_ORPHAN_OBJECTID -5ULL
+
 /*
  * All files have objectids higher than this.
  */
@@ -564,6 +567,7 @@ struct btrfs_root {
 #define BTRFS_INODE_ITEM_KEY		1
 #define BTRFS_INODE_REF_KEY		2
 #define BTRFS_XATTR_ITEM_KEY		8
+#define BTRFS_ORPHAN_ITEM_KEY		9
 
 /* reserve 3-15 close to the inode for later flexibility */
 

print-tree.c

@@ -183,6 +183,9 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
 			di = btrfs_item_ptr(l, i, struct btrfs_dir_item);
 			print_dir_item(l, item, di);
 			break;
+		case BTRFS_ORPHAN_ITEM_KEY:
+			printf("\t\torphan item\n");
+			break;
 		case BTRFS_ROOT_ITEM_KEY:
 			ri = btrfs_item_ptr(l, i, struct btrfs_root_item);
 			read_extent_buffer(l, &root_item, (unsigned long)ri, sizeof(root_item));