Copyright (c) 1996 Doug Rabson All rights reserved. This program is free software. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in...
NAMEvref , vrefl - increment the use count for a vnode
SYNOPSISIn sys/param.h In sys/vnode.h Ft void Fn vref struct vnode *vp Ft void Fn vrefl struct vnode *vp
DESCRIPTIONIncrement the v_usecount field of a vnode.
- Fa 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. during the operation of some algorithm or to store in a data structure) should call Fn vref or Fn vrefl .
Fn vref locks the vnode interlock while Fn vrefl expects the interlock to already be held.