Strange ZFS problem, filesystem claims to be full when clearly not full

[Torbjorn Kristoffersen]

On Thu, Sep 30, 2010 at 7:23 PM, Andriy Gapon <avg at icyb.net.ua> wrote:
> on 30/09/2010 20:07 Oliver Fromme said the following:
>> Last time I had a try at fstat(1), it wasn't able to print
>> actual file names, while lsof was able to do it.  That's
>> why I generally prefer lsof over fstat(1).  For most of my
>> needs fstat(1) is useless if it can't display file names.
>> (I think DragonFly's fstat(1) can do it, FWIW.)
>
> Point taken.
> However fstat still does print inode numbers.

Here's some news, I finally found a file in a user's .spamassassin directory.

$ ls -l .spamassassin/
total 39877936
-rw-------  1 gg  gg      76546048 Sep 30 01:13 auto-whitelist
-rw-------  1 gg  gg            48 Sep 30 01:51 bayes.lock
-rw-------  1 gg  gg      20840448 Sep 30 01:13 bayes_seen
----------  1 gg  gg  552902721536 Sep 30 01:52 temp
-rw-------  1 gg  gg          1573 Sep 30 07:51 user_prefs


Now that is an incredibly huge (and invalid) file! Something like
514GB, far more than the size of this ZFS filesystem.
I removed it, and there was no visible effect in df.  Some funny
business must be happening with spamassassin though,
otherwise this strange file would not be so huge.

I then checked the entire filesystem for files that show up as very
large in 'ls', but freak-sized files came up.