softdep_waitidle: Failed to flush worklist

[Attila Nagy]

Hello,

I have some read only NFS servers, which share a virtual IP (with CARP) 
to provide fault resilience. One of them is the
master server, on which I occasionally modify the NFS share's content.
To make this possible, I have a real UFS file system, on which I have a 
smaller file. This holds the file system image, which I rsync to the 
other servers, if needed.

The setup:
# mdconfig -lu 0
md0     vnode      19G  /data/nfsimg
# mount | grep nfs
/dev/md0 on /nfs (ufs, NFS exported, local, soft-updates)

The modify process is like this:
#mount -o rw -u /nfs
[modify content]
#mount -o ro -u /nfs
[rsync /data/nfsimg to the other machines]

This has worked like a charm until now. Since I've upgraded the OS to 
RELENG_6 as of today, I get the following
line into the syslog everytime I modify something on /nfs and want to do 
a read only remount:
softdep_waitidle: Failed to flush worklist for 0xffffff0054e00630
and the remount command (mount -o ro -u /nfs) fails with:
mount: /dev/md0: Device busy

Before the upgrade (RELENG_6 from Sep 29  2006), I couldn't notice this 
behaviour, so something must have changed in the last 3/4 year. :)

Of course I can turn softupdates off, but it would be interesting to 
know what causes this difference...

-- 
Attila Nagy                                   e-mail: Attila.Nagy at fsn.hu
Free Software Network (FSN.HU)                 phone: +3630 306 6758
http://www.fsn.hu/