How much are filesystem images trusted?

[Dionysus Blazakis]

I've been looking at the HAMMER code a bit.  It seems the mount will
hang the kernel at recovery time if the tail of a undo record contains
a zero size.  I've been told the filesystem is implicitly trusted, but
I think a failed assert would be better than the stuck while loop.

I have a small disk image to illustrate the hang at:
http://leaf.dragonflybsd.org/~dion/hammer.small.bz2

This obviously isn't a high priority, but I'm interested in hearing
opinions on it (does this kind of bug interest us?).

-- Dion