zfs diff returns error

[trinxie]

I have a problem when running "zfs diff", it returns an error "unable to determine path or stats for object 14 in...". See below. Anyone that have any idea what can be wrong?

I planned to use zfs diff to list all deleted files between today and last week.
I have tried to google this but I cannot get any clear answer.


[root@nas] ~# zfs diff MyVolume/BackupDS@auto-20130923.2000-3m MyVolume/BackupDS@auto-20131001.2100-3m
M /mnt/MyVolume/BackupDS/
Unable to determine path or stats for object 14 in MyVolume/BackupDS@auto-20130923.2000-3m: Invalid argument

>zfs list -r -t snapshot -o name,creation,used MyVolume/BackupDS
MyVolume/BackupDS@auto-20130923.2000-3m Mon Sep 23 20:00 2013 1.77M
MyVolume/BackupDS@auto-20130923.2100-3m Mon Sep 23 21:00 2013 96K
MyVolume/BackupDS@auto-20130924.1900-3m Tue Sep 24 19:00 2013 2.03M
....
MyVolume/BackupDS@auto-20130930.2000-3m Mon Sep 30 20:00 2013 0
MyVolume/BackupDS@auto-20130930.2100-3m Mon Sep 30 21:00 2013 0
MyVolume/BackupDS@auto-20131001.1900-3m Tue Oct 1 19:00 2013 3.90M
MyVolume/BackupDS@auto-20131001.2000-3m Tue Oct 1 20:00 2013 112K
MyVolume/BackupDS@auto-20131001.2100-3m Tue Oct 1 21:00 2013 256K

zfs status returns ok:
[root@nas] ~# zpool status
pool: MyVolume
state: ONLINE
scan: scrub repaired 0 in 2h55m with 0 errors on Mon Sep 23 05:55:58 2013
config:

NAME STATE READ WRITE CKSUM
MyVolume ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
gptid/9739b299-53ac-11e2-90ca-bc5ff4746c08 ONLINE 0 0 0
gptid/97ac85c3-53ac-11e2-90ca-bc5ff4746c08 ONLINE 0 0 0

errors: No known data errors

 

[paleoN]

Anyone that have any idea what can be wrong?

Sounds like this or something similar.

 

[trinxie]

Thanks!
So it seems related to hard linked files or directories OR zfs diff bug?...

I did seach for all hardlink files in my dataset using:
find . -type f -a \! -links 1
Result: No hard linked files

As I understand It is hard to search for hardlinked directories, I will have not done this manually...

When I searched for my original problem I did find posts regarding zfs diff panic or deadlocks,. I was obviously not reading enough.
The following was taken from the link provided by paleoN:
There is probably nothing wrong with the snapshots. This is a bug in ZFS diff. The ZPL parent pointer is only guaranteed to be correct for directory objects. What you probably have is a file that was hard linked multiple times and the parent pointer (i.e. directory) was recycled and is now a file

I am not experienced enough to understand if I actually have a corrupt filesystem or that I have stepped into a zfs diff bug. I cannot understand the output from "zdb -vvv ...."

Can anyone else reading this try to run a zfs diff between two (distant) snapshots and see if it works ok or not?

 

[paleoN]

I am not experienced enough to understand if I actually have a corrupt filesystem or that I have stepped into a zfs diff bug. I cannot understand the output from "zdb -vvv ...."

I would say it's a zfs diff bug. FYI, you can point zdb to a particular object, i.e. 14, by appending it at the end of the command.