cd /.zfs/snapshot hangs (tmux put to uninterruptible sleep)

[Niklaas Baudet von Gersdorff]

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On 26/10/15 12:44, Matthew Seaman wrote:
> Actually, here is the problem:
> 
> stingray:/:# zfs destroy -r tank/.......1 cannot unmount
> '/.......1': Device busy
> 
> But that is easily fixed by:
> 
> stingray:/:# zfs umount -f /.......1 stingray:/:# zfs destroy -r
> tank/.......1
> 
> I wonder if that's worth a PR?  I recall now this is exactly what I
> ran into before, but it seems rather different to what you're
> seeing.

Aha!

I am not sure but it could be that it is related. (Sorry, unlike you I
haven't further investigated on what caused the error i.e., I am not
100% sure.)

What I realised yesterday was that I had several more processes stuck
in D. All of these were caused by a script [1] hat I use to create
snapshots of my ZFS filesystems regulary. It creates snapshots and
*deletes* old ones.

1: https://bitbucket.org/mmichele/zfssnap

My guess is now that the script caused the uninterruptible sleep of a
process (several times because I run it quite regularly) when it tried
to destroy an old snapshot. Then I came in and (because I wanted to
restore an accidentally deleted file) `cd /.zfs./snapshot` and
couldn't get access (the process hang) because the script already
messed up everything.

Does this make sense?

- -- 
Niklaas
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