ZFS snapshot renames failing after upgrade to 9.2

[krichy at tvnetwork.hu]

Dear Gerrit,

The problem is that when renaming snapshots, the mounted snapshot is tried 
to be mounted again under a new name. Maybe, the rename code does not 
remount them to their proper position, that may be the problem.

I will look if I can check or fix it.

Did this work in 9.1?

Regards,


Kojedzinszky Richard
Euronet Magyarorszag Informatikai Zrt.

On Fri, 20 Dec 2013, krichy at tvnetwork.hu wrote:

> Date: Fri, 20 Dec 2013 10:19:15 +0100 (CET)
> From: krichy at tvnetwork.hu
> To: Gerrit Kühn <gerrit.kuehn at aei.mpg.de>
> Cc: freebsd-fs at freebsd.org
> Subject: Re: ZFS snapshot renames failing after upgrade to 9.2
> 
> Dear Gerrit,
>
> It is not a solution, but I use different snapshot handling mechanisms. I 
> wrote a simple script which handles that, and the snapshots are named by its 
> creation timestamp. I think it is more usable to see that when that snapshot 
> was exactly taken, and the script thus only does snapshot creation, and 
> deletion, no renames.
>
> That scripts only limitation is that it is planned to run hourly, creating 
> hourly snapshots, and when run again, it queries the existing one's list, and 
> decides which to keep or remove. Thus you have to run it hourly in cron like:
> # crontab -l
> 0 *     * * *   /usr/local/sbin/zfs-snapshot
>
> Regards,
>
>
> Kojedzinszky Richard
> Euronet Magyarorszag Informatikai Zrt.
>
> On Fri, 20 Dec 2013, Gerrit Kühn wrote:
>
>> Date: Fri, 20 Dec 2013 10:05:22 +0100
>> From: Gerrit Kühn <gerrit.kuehn at aei.mpg.de>
>> To: krichy at tvnetwork.hu
>> Cc: freebsd-fs at freebsd.org
>> Subject: Re: ZFS snapshot renames failing after upgrade to 9.2
>> 
>> 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
>