K 10
svn:author
V 4
kato
K 8
svn:date
V 27
1997-04-29T02:06:07.000000Z
K 7
svn:log
V 554
Revised fix for locking violation when unionfs calls vput with
UN_KLOCK flag.

When UN_KLOCK is set, VOP_UNLOCK should keep uppervp locked and clear
UN_ULOCK flag.  To do this, when UN_KLOCK is set, (1) union_unlock
clears UN_ULOCK and does not clear UN_KLOCK, (2) union_lock() does not
access uppervp and does not clear UN_KLOCK, and (3) callers of
vput/VOP_UNLOCK should clear UN_KLOCK.  For example, vput becomes:

	SETKLOCK(union_node);
	vput(vnode);
	CLEARKLOCK(union_node);

where SETKLOCK macro sets UN_KLOCK and CLEARKLOCK macro clears
UN_KLOCK.

END