[issue1276] panic: assertion: volume->io.lock.refs == 0 in hammer_unload_volume

[Matthew Dillon]

::Thomas Nikolajsen <thomas.nikolajsen at mail.dk> added the comment:
::
::New crash dump using HEAD of Feb 12, 2009.
::
::Uploading to leaf as *.29 (with all modules in use).
::
:: -thomas
:
:    Thomas, I believe I have found it.  Please try the enclosed patch.
:    When a buffer collision occurs under heavy loads a ref on the volume
:    structure was not being undone, leading to a ref count leak on the
:    volume structure which will result in a panic on umount.
:
:    This fix will not make it into 2.2.  It needs to be tested and verified
:    to have fixed the problem, then I'll commit and MFC it.
: 	
:					-Matt
:					Matthew Dillon 
:					<dillon at backplane.com>

    I've committed the patch.  Did you try it and get any more crashes
    on umount from that particular volume.io.refs assertion?

						-Matt