am 4b8b59a7: zero the entire journal instead of just the first block

Merge commit '4b8b59a7cd0e1413dcf9973c4bbd7eb65a444c4c'

* commit '4b8b59a7cd0e1413dcf9973c4bbd7eb65a444c4c':
  zero the entire journal instead of just the first block