NAME
vhold, vdrop
— Acquire/release an auxiliary
reference on a vnode
SYNOPSIS
#include
<sys/param.h>
#include <sys/vnode.h>
void
vhold(struct
vnode *vp);
void
vdrop(struct
vnode *vp);
DESCRIPTION
Thevhold()
function acquires an auxiliary reference on a vnode by incrementing the
v_auxrefs field. Auxiliary references do not reactivate
a vnode or move it to the cache if it resides on the free list, but they will
prevent the vnode from being recycled (if not already being recycled), or
reused. Auxiliary references are used to associate auxiliary structures such
as namecache records with the vnode for those cases where the intent is to not
allow the vnode to be immediately recycled. Auxiliary references are also used
to access a vnode via an auxiliary structure without having to hold a deep
stack of locks that might create deadlock issues for the caller.
The
vdrop()
function decrements the v_auxrefs field. If the vnode
has been deactivated and resides in the cache, it will be moved to the free
list when v_auxrefs drops to 0.
SEE ALSO
vget(9), vnode(9), vn_lock(9), vn_unlock(9), vput(9), vref(9), vrele(9)
AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>.