Could we schedule I/O in such a fashion as to be outside of locks involved in
a deadlock situation?

Cache lock = sync() lock in ArcCache.
CBD lock is the individual mutex of a CBD.

What are the conditions for achieving this?

We must have done all cache list modifications before releasing the cache lock.
   - This ensures another thread doesn't, for example, recover a CBD with one
   id which, in fact, is being "renamed" to another id.
   - We must also do this to protect the state of the various lists which
   constitute a chunk of the cache state.  Question, is the state of a CDB's
   content part of the cache state?