bcachefs: Include b->ob.nr in cached_btree_node_to_text()

We have a bug report that looks like we might be leaking open buckets -
let's check if they got left attached to the cached btree node.

Signed-off-by: Kent Overstreet <[email protected]>

Author: Kent Overstreet

fs/bcachefs/debug.c

@@ -492,6 +492,8 @@ static void bch2_cached_btree_node_to_text(struct printbuf *out, struct bch_fs *
 	prt_printf(out, "journal pin %px:\t%llu\n",
 		   &b->writes[1].journal, b->writes[1].journal.seq);
 
+	prt_printf(out, "ob:\t%u\n", b->ob.nr);
+
 	printbuf_indent_sub(out, 2);
 }