Increment the
v_usecount
field of a vnode.
vp
|
|
the vnode to increment
|
Each vnode maintains a reference count of how many parts of the system
are using the vnode.
This allows the system to detect when a vnode is
no longer being used and can be safely recycled for a different file.
Any code in the system which is using a vnode (e.g.amp; during the
operation of some algorithm or to store in a data structure) should
call
vref()
or
vrefl().
vref()
locks the vnode interlock while
vrefl()
expects the interlock to already be held.