e88c11f417
which relied on taking extra vnode refs. Having benchmarked various experimental changes over the past few months it seems that it's better to avoid vnode refs as much as possible. cwdi_lock as a RW lock already did that to some extent for getcwd() and will permit the same for namei() too.
162 lines
3.7 KiB
C
162 lines
3.7 KiB
C
/* $NetBSD: vfs_cwd.c,v 1.6 2020/04/21 21:42:47 ad Exp $ */
|
|
|
|
/*-
|
|
* Copyright (c) 2008, 2020 The NetBSD Foundation, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* 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 the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
/*
|
|
* Current working directory.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
__KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.6 2020/04/21 21:42:47 ad Exp $");
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/atomic.h>
|
|
#include <sys/filedesc.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/vnode.h>
|
|
|
|
static int cwdi_ctor(void *, void *, int);
|
|
static void cwdi_dtor(void *, void *);
|
|
|
|
static pool_cache_t cwdi_cache;
|
|
|
|
void
|
|
cwd_sys_init(void)
|
|
{
|
|
|
|
cwdi_cache = pool_cache_init(sizeof(struct cwdinfo), coherency_unit,
|
|
0, 0, "cwdi", NULL, IPL_NONE, cwdi_ctor, cwdi_dtor, NULL);
|
|
KASSERT(cwdi_cache != NULL);
|
|
}
|
|
|
|
/*
|
|
* Create an initial cwdinfo structure, using the same current and root
|
|
* directories as curproc.
|
|
*/
|
|
struct cwdinfo *
|
|
cwdinit(void)
|
|
{
|
|
struct cwdinfo *cwdi;
|
|
struct cwdinfo *copy;
|
|
|
|
cwdi = pool_cache_get(cwdi_cache, PR_WAITOK);
|
|
copy = curproc->p_cwdi;
|
|
|
|
rw_enter(©->cwdi_lock, RW_READER);
|
|
cwdi->cwdi_cdir = copy->cwdi_cdir;
|
|
if (cwdi->cwdi_cdir)
|
|
vref(cwdi->cwdi_cdir);
|
|
cwdi->cwdi_rdir = copy->cwdi_rdir;
|
|
if (cwdi->cwdi_rdir)
|
|
vref(cwdi->cwdi_rdir);
|
|
cwdi->cwdi_edir = copy->cwdi_edir;
|
|
if (cwdi->cwdi_edir)
|
|
vref(cwdi->cwdi_edir);
|
|
cwdi->cwdi_cmask = copy->cwdi_cmask;
|
|
cwdi->cwdi_refcnt = 1;
|
|
rw_exit(©->cwdi_lock);
|
|
|
|
return (cwdi);
|
|
}
|
|
|
|
static int
|
|
cwdi_ctor(void *arg, void *obj, int flags)
|
|
{
|
|
struct cwdinfo *cwdi = obj;
|
|
|
|
rw_init(&cwdi->cwdi_lock);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
cwdi_dtor(void *arg, void *obj)
|
|
{
|
|
struct cwdinfo *cwdi = obj;
|
|
|
|
rw_destroy(&cwdi->cwdi_lock);
|
|
}
|
|
|
|
/*
|
|
* Make p2 share p1's cwdinfo.
|
|
*/
|
|
void
|
|
cwdshare(struct proc *p2)
|
|
{
|
|
struct cwdinfo *cwdi;
|
|
|
|
cwdi = curproc->p_cwdi;
|
|
|
|
atomic_inc_uint(&cwdi->cwdi_refcnt);
|
|
p2->p_cwdi = cwdi;
|
|
}
|
|
|
|
/*
|
|
* Make sure proc has only one reference to its cwdi, creating
|
|
* a new one if necessary.
|
|
*/
|
|
void
|
|
cwdunshare(struct proc *p)
|
|
{
|
|
struct cwdinfo *cwdi = p->p_cwdi;
|
|
|
|
if (cwdi->cwdi_refcnt > 1) {
|
|
cwdi = cwdinit();
|
|
cwdfree(p->p_cwdi);
|
|
p->p_cwdi = cwdi;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Release a cwdinfo structure.
|
|
*/
|
|
void
|
|
cwdfree(struct cwdinfo *cwdi)
|
|
{
|
|
|
|
if (atomic_dec_uint_nv(&cwdi->cwdi_refcnt) > 0)
|
|
return;
|
|
|
|
vrele(cwdi->cwdi_cdir);
|
|
if (cwdi->cwdi_rdir)
|
|
vrele(cwdi->cwdi_rdir);
|
|
if (cwdi->cwdi_edir)
|
|
vrele(cwdi->cwdi_edir);
|
|
pool_cache_put(cwdi_cache, cwdi);
|
|
}
|
|
|
|
void
|
|
cwdexec(struct proc *p)
|
|
{
|
|
|
|
cwdunshare(p);
|
|
|
|
if (p->p_cwdi->cwdi_edir) {
|
|
vrele(p->p_cwdi->cwdi_edir);
|
|
}
|
|
}
|