UBIFS recovery taking too long

[David Mosberger-Tang]

We recently encountered a strange issue where UBIFS recovery is
suddenly taking a lot longer than usual (v3.7-based kernel).  In our
case, recovery took about 30 seconds.  This caused a serious problem
because our watchdog timer was set to 15 seconds, effectively
rendering the devices unbootable.

Does anybody know what triggers this slow recovery mode?  Also, how
can we calculate a worst-case recovery time for a given flash
chip-size.

Thanks,

  --david