Bug 151330

i am using FreeBSD ZFS+NFS as filesystem server, support nfs filesystem for other organization, i can successfully to create zpool and create zfs filesystem, set sherenfs=on to share nfs to another machine.

but today when i execute "zfs clone za/za2@empty za/za2/empty", then all nfs client got error:
df: `/backup': Input/output error

i ran "showmount -e" at freebsd server, i found nothing display, before clone it show all zfs filesystem what can be nfs mount at client.

Fix: 

at freebsd: ps aux|grep mountd
kill mountd session, and restart mountd, then execute "showmount -e", all nfs share point will display.
How-To-Repeat: 1. create a zpool name za1
2. zfs set sharenfs=on za1
3. make sure all nfs process has been started.execute "showmount -e" will display /za1 can be nfs mount.
4. go to another machine which install redhat linux 5.3.
5. mount nfs using oralce recommendation option:
mount -o rw,bg,hard,rsize=32768,wsize=32768,vers=3,nointr,timeo=600,tcp 192.168.56.130:/za1 /backup
6. at freebsd server, execute "zfs snapshot za1@empty", then execute "zfs clone za1@empty za1/empty", after that, execute "showmount -e", nothing display.
7. go to client machine, execute "df -k" will get Input/output error.