— decrement the use count for a vnode
Decrement the v_usecount
field of a vnode.
- the vnode to decrement
() function takes an unlocked vnode and returns with
the vnode unlocked.
() function should be given a locked vnode as
argument, the vnode is unlocked after the function returned. The
() is operationally equivalent to calling
followed by vrele(9)
() function takes a locked vnode as argument, and
returns with the vnode locked.
Any code in the system which signified its use of a vnode by usecount should
call one of the listed function to decrement use counter. If the
field of the non-doomed vnode reaches zero,
then it will be inactivated and placed on the free list. Since the functions
might need to call VOPs for the vnode, the Giant
should be conditionally locked around the call.
The hold count for the vnode is always greater or equal to the usecount.
Non-forced unmount fails when mount point owns a vnode that has non-zero
usecount, see vflush(9)
This manual page was written by Doug Rabson