hammer + nfs => Input/output error

[Thomas Nikolajsen <thomas.nikolajsen@xxxxxxx>]

Using HAMMER for nfs exports, nfs client often get in a state
where access to most files return `Input/output error' (EIO state).

Example:
 - nfs server using HAMMER for all exports
 - nfs client mount of usr/src and /home/thomas (/usr/obj local)
When building & installing world & kernel /home/thomas often get in `EIO state'.
/home/thomas is only lightly used (contrary to /usr/src).
Only known solution (besides reboot) is remounting /home/thomas.

When this happens nfs server log error (multiple times):
lookupdotdot failed 2 dvp 0xca3087d0

Is core dump needed?
(will decrease hw.physmem; 2G now)

 -thomas