In addition to the fixes following the Rich's suggestions (comment 11),
the take 2 patch contains ...
. to register cos_post_op are POSTOP only to avoid the deadlock between
the transaction and cos change_lock.
. to move transaction begin before "finding" an backend entry in
ldbm_back_add/delete/modify/modrdn to avoid the deadlock between the
serial lock and the individual entry cache lock.