freebsd-dev/sys/cddl/contrib/opensolaris/uts/common/fs/vnode.c
Mateusz Guzik 752fc07d33 vfs: implement v_holdcnt/v_usecount manipulation using atomic ops
Transitions 0->1 and 1->0 (which decide e.g. on putting the vnode on the free
list) of either counter are still guarded with vnode interlock.

Reviewed by:	kib (earlier version)
Tested by:	pho
2015-07-16 13:57:05 +00:00

105 lines
3.0 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
*/
/* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
/*
* University Copyright- Copyright (c) 1982, 1986, 1988
* The Regents of the University of California
* All Rights Reserved
*
* University Acknowledgment- Portions of this document are derived from
* software developed by the University of California, Berkeley, and its
* contributors.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/taskq.h>
#include <sys/vnode.h>
/* Extensible attribute (xva) routines. */
/*
* Zero out the structure, set the size of the requested/returned bitmaps,
* set AT_XVATTR in the embedded vattr_t's va_mask, and set up the pointer
* to the returned attributes array.
*/
void
xva_init(xvattr_t *xvap)
{
bzero(xvap, sizeof (xvattr_t));
xvap->xva_mapsize = XVA_MAPSIZE;
xvap->xva_magic = XVA_MAGIC;
xvap->xva_vattr.va_mask = AT_XVATTR;
xvap->xva_rtnattrmapp = &(xvap->xva_rtnattrmap)[0];
}
/*
* If AT_XVATTR is set, returns a pointer to the embedded xoptattr_t
* structure. Otherwise, returns NULL.
*/
xoptattr_t *
xva_getxoptattr(xvattr_t *xvap)
{
xoptattr_t *xoap = NULL;
if (xvap->xva_vattr.va_mask & AT_XVATTR)
xoap = &xvap->xva_xoptattrs;
return (xoap);
}
static void
vn_rele_inactive(vnode_t *vp)
{
vrele(vp);
}
/*
* Like vn_rele() except if we are going to call VOP_INACTIVE() then do it
* asynchronously using a taskq. This can avoid deadlocks caused by re-entering
* the file system as a result of releasing the vnode. Note, file systems
* already have to handle the race where the vnode is incremented before the
* inactive routine is called and does its locking.
*
* Warning: Excessive use of this routine can lead to performance problems.
* This is because taskqs throttle back allocation if too many are created.
*/
void
vn_rele_async(vnode_t *vp, taskq_t *taskq)
{
VERIFY(vp->v_count > 0);
VI_LOCK(vp);
if (vp->v_count == 1 && !(vp->v_iflag & VI_DOINGINACT)) {
VI_UNLOCK(vp);
VERIFY(taskq_dispatch((taskq_t *)taskq,
(task_func_t *)vn_rele_inactive, vp, TQ_SLEEP) != 0);
return;
}
refcount_release(&vp->v_usecount);
vdropl(vp);
}