kern/161968: [zfs] [hang] renaming snapshot with -r including a zvol snapshot causes total ZFS freeze/lockup

[Shane Ambler]

The following reply was made to PR kern/161968; it has been noted by GNATS.

From: Shane Ambler <FreeBSD at ShaneWare.Biz>
To: bug-followup at FreeBSD.org, peter.maloney at brockmann-consult.de
Cc:  
Subject: Re: kern/161968: [zfs] [hang] renaming snapshot with -r including
 a zvol snapshot causes total ZFS freeze/lockup
Date: Thu, 19 Jul 2012 01:59:46 +0930

 I am running 9.0-RELEASE-p1 amd64 clang built world and get a hang with 
 zfs rename -r. I find anything already running mostly keeps running (top 
 started before the rename will hang) but any (uncached?) disk access 
 will cause running progs to hang as well. No new progs can start not 
 even a console login. I need to hard reset.
 
 Hardware is an ASUS P8H61-M LE/USB3 with corei5 and 8GB RAM using a 
 WD10EARS-00Y5B1 (WD green 1TB SATA2).
 Partitioned with 1 64k boot partition and 1 zfs partition. Single disk 
 zpool. The volume I have is allocated to swap.
 
 The commands I used for the volume are -
 zfs create -V 16G zrp/swap0
 zfs set org.freebsd:swap=on zrp/swap0
 zfs set copies=1 zrp/swap0
 
  From a clean pool with no snapshots -
 zfs snapshot -r zrp at daily.01 -- works
 zfs rename -r zrp at daily.01 zrp at daily.02 -- hangs
 
 Alternatively -
 zfs snapshot -r zrp at daily.01 -- works
 zfs rename -r zrp/swap0 at daily.01 zrp/swap0 at daily.02 -- works
 zfs rename -r zrp at daily.01 zrp at daily.02 -- works
 zfs rename -r zrp at daily.02 zrp at daily.03 -- hangs - now renames vol