panic: assertion: volume->io.lock.refs == 0 in hammer_unload_volume

[Matthew Dillon]

:I've got this panic multiple times at shutdown;
:this is on nfs server using hammer for exports.
:
:Crash dump on leaf in crash/hammer/ask/*.4.
:
:Panic only seen after running buildworld on client w/ usr/src & usr/obj nfs=
: mounted;
:no problem when client uses local file system (e.g. hammer) for /usr/obj.
:
: -thomas
:-

    I made a commit which may or may not fix this.  Please report if it
    does not, there could also be an issue with shutting down NFS services
    on the server side.

					-Matt