Re: kern/38717: sysinst shouldn't create LFS file systems

[Alan Barrett <apb%cequrux.com@localhost>]

On Wed, 11 Jun 2008, David Holland wrote:
> Well, what happens is that block pointers get updated synchronously
> without the data they point to having been written out; so if you
> crash you can get whatever crap was on the disk in that location
> previously.

Yes.  I had incorrectly thought that the random content that I saw was
in files that had been modified in place, but I now know that they were
in files that had been newly created and renamed, so your description
matches what I saw.

>  > >  > ffs with -o async [...]
>  > > ... cannot reasonably be expected to work.
> 
> Crashing is a bug, yes. I read what you wrote as meaning that the fs
> corruption after a crash was even worse, though; that is to be
> expected. (IME, crashes with ffs -o async are often unrecoverable.)

When I said "ffs with -o async is even worse", I meant "leads to a
guaranteed system crash much more quickly [than ffs without -o async]".

--apb (Alan Barrett)