The following reply was made to PR kern/156781; it has been noted by GNATS.
Date: Fri, 13 Apr 2012 09:25:16 +0200
Is the faulty dataset shared over NFS? If so, is it the new NFS server
(default in 9.0 I think) or the old (default in 8.2)?
My ZFS over NFS on 8-STABLE has slightly similar problems on the NFS
client side, but only when viewed by a Linux client. A simple "ls -l" on
the .zfs/snapshot directory on a Linux client hangs the dataset. And
these lines show up in /var/log/messages when reloading the NFS server:
Apr 12 10:08:38 [hostname] mountd[54479]: can't delete exports for
/tank/[...]/.zfs/snapshot/replication-20120411112000: Invalid argument
And an "ls" without "-l" on a Linux client shows that the ones mentioned
in messages are files and the rest are directories (Linux shells
generally color them blue and append a / for directories).
I can only guess that they may be related.