ZFS snapshot renames failing after upgrade to 9.2

[Gerrit Kühn]

On Thu, 19 Dec 2013 20:08:22 +0100 (CET) krichy at tvnetwork.hu wrote about
Re: ZFS snapshot renames failing after upgrade to 9.2:

KH> So a simple renaming can cause your system to hang?

No, it does not hang completely.
Just the snapshots become unusable. This night, it happened again:

---
root at shapeshifter:~ # ll /tank/git/.zfs/snapshot/
ls: daily.6: Device busy
total 33
drwxr-xr-x  12 211   211    25 Dec 19 09:18 daily.0/
drwxr-xr-x  12 211   211    25 Dec 19 00:00 daily.1/
drwxr-xr-x  12 211   211    24 Dec 18 00:00 daily.2/
drwxr-xr-x  12 211   211    24 Dec 17 00:00 daily.3/
drwxr-xr-x  12 211   211    24 Dec 16 00:00 daily.4/
drwxr-xr-x  12 211   211    24 Dec 14 00:00 daily.5/
drwxr-xr-x  12 211   211    24 Dec 15 00:00 weekly.0/
drwxr-xr-x  12 211   211    24 Dec  8 00:00 weekly.1/
drwxr-xr-x  12 211   211    24 Dec  1 00:00 weekly.2/
drwxr-xr-x  12 211   211    24 Nov 17 00:00 weekly.3/
drwxr-xr-x  12 211   211    24 Nov 10 00:00 weekly.4/
drwxr-xr-x   2 root  wheel   3 Oct 20 00:00 weekly.5/
drwxr-xr-x   2 root  wheel   3 Oct  6 00:00 weekly.6/
---

root at shapeshifter:~ # zfs list -r -t snapshot -o
name,creation,used,referenced tank/git NAME
CREATION                USED  REFER tank/git at weekly.6  Sun Oct  6  0:00
2013  42.6K  62.8K tank/git at weekly.5  Sun Oct 20  0:00 2013  42.6K  62.8K
tank/git at weekly.4  Sun Nov 10  0:00 2013  29.5M   146G
tank/git at weekly.3  Sun Nov 17  0:00 2013  27.1M   146G
tank/git at weekly.2  Sun Dec  1  0:00 2013  26.3M   146G
tank/git at weekly.1  Sun Dec  8  0:00 2013  27.3M   146G
tank/git at daily.6   Sat Dec 14  0:00 2013  26.5M   147G
tank/git at weekly.0  Sun Dec 15  0:00 2013  25.2M   147G
tank/git at daily.5   Mon Dec 16  0:00 2013  24.7M   147G
tank/git at daily.4   Tue Dec 17  0:00 2013  24.9M   147G
tank/git at daily.3   Wed Dec 18  0:00 2013  25.7M   147G
tank/git at daily.2   Thu Dec 19  0:00 2013  25.8M   147G
tank/git at daily.1   Thu Dec 19  9:19 2013  25.0M   147G
tank/git at daily.0   Fri Dec 20  0:00 2013  26.8M   147G
---


As you can see, the snapshot rotating got stuck somewhere. What is
displayed under .zfs/snapshot does not reflect what zfs is really seeing:
daily.6 is inaccessible, and the rotation that happened so far is not
reflected under .zfs/snapshot, either.


cu
  Gerrit