Module Name: src
Committed By: ad
Date: Sat Jan 25 15:54:04 UTC 2020
Modified Files:
src/sys/compat/netbsd32 [ad-namecache]: netbsd32_fs.c
src/sys/kern [ad-namecache]: kern_exec.c kern_proc.c uipc_usrreq.c
vfs_cwd.c vfs_getcwd.c vfs_lookup.c vfs_mount.c vfs_subr.c
vfs_syscalls.c vfs_vnode.c
src/sys/miscfs/procfs [ad-namecache]: procfs_vnops.c
src/sys/sys [ad-namecache]: filedesc.h vfs_syscalls.h
Log Message:
Make cwdinfo use mostly lockless, and largely hide the details in vfs_cwd.c.
To generate a diff of this commit:
cvs rdiff -u -r1.85 -r1.85.2.1 src/sys/compat/netbsd32/netbsd32_fs.c
cvs rdiff -u -r1.485.2.1 -r1.485.2.2 src/sys/kern/kern_exec.c
cvs rdiff -u -r1.239 -r1.239.2.1 src/sys/kern/kern_proc.c
cvs rdiff -u -r1.194 -r1.194.4.1 src/sys/kern/uipc_usrreq.c
cvs rdiff -u -r1.4 -r1.4.62.1 src/sys/kern/vfs_cwd.c
cvs rdiff -u -r1.53.2.3 -r1.53.2.4 src/sys/kern/vfs_getcwd.c
cvs rdiff -u -r1.212.4.8 -r1.212.4.9 src/sys/kern/vfs_lookup.c
cvs rdiff -u -r1.73.2.1 -r1.73.2.2 src/sys/kern/vfs_mount.c
cvs rdiff -u -r1.478.2.2 -r1.478.2.3 src/sys/kern/vfs_subr.c
cvs rdiff -u -r1.539.2.2 -r1.539.2.3 src/sys/kern/vfs_syscalls.c
cvs rdiff -u -r1.105.2.5 -r1.105.2.6 src/sys/kern/vfs_vnode.c
cvs rdiff -u -r1.207 -r1.207.2.1 src/sys/miscfs/procfs/procfs_vnops.c
cvs rdiff -u -r1.65 -r1.65.2.1 src/sys/sys/filedesc.h
cvs rdiff -u -r1.26 -r1.26.2.1 src/sys/sys/vfs_syscalls.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/compat/netbsd32/netbsd32_fs.c
diff -u src/sys/compat/netbsd32/netbsd32_fs.c:1.85 src/sys/compat/netbsd32/netbsd32_fs.c:1.85.2.1
--- src/sys/compat/netbsd32/netbsd32_fs.c:1.85 Thu Sep 26 01:32:09 2019
+++ src/sys/compat/netbsd32/netbsd32_fs.c Sat Jan 25 15:54:03 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: netbsd32_fs.c,v 1.85 2019/09/26 01:32:09 christos Exp $ */
+/* $NetBSD: netbsd32_fs.c,v 1.85.2.1 2020/01/25 15:54:03 ad Exp $ */
/*
* Copyright (c) 1998, 2001 Matthew R. Green
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: netbsd32_fs.c,v 1.85 2019/09/26 01:32:09 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: netbsd32_fs.c,v 1.85.2.1 2020/01/25 15:54:03 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -740,13 +740,12 @@ netbsd32___getcwd(struct lwp *l, const s
syscallarg(char *) bufp;
syscallarg(size_t) length;
} */
- struct proc *p = l->l_proc;
int error;
char *path;
char *bp, *bend;
int len = (int)SCARG(uap, length);
int lenused;
- struct cwdinfo *cwdi;
+ struct vnode *dvp;
if (len > MAXPATHLEN*4)
len = MAXPATHLEN*4;
@@ -764,11 +763,10 @@ netbsd32___getcwd(struct lwp *l, const s
* limit it to N/2 vnodes for an N byte buffer.
*/
#define GETCWD_CHECK_ACCESS 0x0001
- cwdi = p->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
- error = getcwd_common (cwdi->cwdi_cdir, NULL, &bp, path, len/2,
+ dvp = cwdcdir();
+ error = getcwd_common (dvp, NULL, &bp, path, len/2,
GETCWD_CHECK_ACCESS, l);
- rw_exit(&cwdi->cwdi_lock);
+ vrele(dvp);
if (error)
goto out;
Index: src/sys/kern/kern_exec.c
diff -u src/sys/kern/kern_exec.c:1.485.2.1 src/sys/kern/kern_exec.c:1.485.2.2
--- src/sys/kern/kern_exec.c:1.485.2.1 Fri Jan 17 21:47:35 2020
+++ src/sys/kern/kern_exec.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: kern_exec.c,v 1.485.2.1 2020/01/17 21:47:35 ad Exp $ */
+/* $NetBSD: kern_exec.c,v 1.485.2.2 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 2008, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.485.2.1 2020/01/17 21:47:35 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.485.2.2 2020/01/25 15:54:03 ad Exp $");
#include "opt_exec.h"
#include "opt_execfmt.h"
@@ -664,7 +664,7 @@ exec_makepathbuf(struct lwp *l, const ch
char *path, *bp;
size_t len, tlen;
int error;
- struct cwdinfo *cwdi;
+ struct vnode *dvp;
path = PNBUF_GET();
if (seg == UIO_SYSSPACE) {
@@ -690,11 +690,10 @@ exec_makepathbuf(struct lwp *l, const ch
memmove(bp, path, len);
*(--bp) = '/';
- cwdi = l->l_proc->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
- error = getcwd_common(cwdi->cwdi_cdir, NULL, &bp, path, MAXPATHLEN / 2,
+ dvp = cwdcdir();
+ error = getcwd_common(dvp, NULL, &bp, path, MAXPATHLEN / 2,
GETCWD_CHECK_ACCESS, l);
- rw_exit(&cwdi->cwdi_lock);
+ vrele(dvp);
if (error)
goto err;
@@ -1111,6 +1110,7 @@ static void
emulexec(struct lwp *l, struct exec_package *epp)
{
struct proc *p = l->l_proc;
+ struct cwdinfo *cwdi;
/* The emulation root will usually have been found when we looked
* for the elf interpreter (or similar), if not look now. */
@@ -1119,9 +1119,10 @@ emulexec(struct lwp *l, struct exec_pack
emul_find_root(l, epp);
/* Any old emulation root got removed by fdcloseexec */
- rw_enter(&p->p_cwdi->cwdi_lock, RW_WRITER);
- p->p_cwdi->cwdi_edir = epp->ep_emul_root;
- rw_exit(&p->p_cwdi->cwdi_lock);
+ KASSERT(p == curproc);
+ cwdi = cwdenter(RW_WRITER);
+ cwdi->cwdi_edir = epp->ep_emul_root;
+ cwdexit(cwdi);
epp->ep_emul_root = NULL;
if (epp->ep_interp != NULL)
vrele(epp->ep_interp);
Index: src/sys/kern/kern_proc.c
diff -u src/sys/kern/kern_proc.c:1.239 src/sys/kern/kern_proc.c:1.239.2.1
--- src/sys/kern/kern_proc.c:1.239 Tue Dec 31 13:07:13 2019
+++ src/sys/kern/kern_proc.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: kern_proc.c,v 1.239 2019/12/31 13:07:13 ad Exp $ */
+/* $NetBSD: kern_proc.c,v 1.239.2.1 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc.
+ * Copyright (c) 1999, 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.239 2019/12/31 13:07:13 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_proc.c,v 1.239.2.1 2020/01/25 15:54:03 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_kstack.h"
@@ -106,6 +106,7 @@ __KERNEL_RCSID(0, "$NetBSD: kern_proc.c,
#include <sys/exec.h>
#include <sys/cpu.h>
#include <sys/compat_stub.h>
+#include <sys/vnode.h>
#include <uvm/uvm_extern.h>
#include <uvm/uvm.h>
@@ -470,7 +471,7 @@ proc0_init(void)
p->p_cred = cred0;
/* Create the CWD info. */
- rw_init(&cwdi0.cwdi_lock);
+ mutex_init(&cwdi0.cwdi_lock, MUTEX_DEFAULT, IPL_NONE);
/* Create the limits structures. */
mutex_init(&limit0.pl_lock, MUTEX_DEFAULT, IPL_NONE);
@@ -2588,7 +2589,7 @@ fill_cwd(struct lwp *l, pid_t pid, void
struct proc *p;
char *path;
char *bp, *bend;
- struct cwdinfo *cwdi;
+ const struct cwdinfo *cwdi;
struct vnode *vp;
size_t len, lenused;
@@ -2603,11 +2604,12 @@ fill_cwd(struct lwp *l, pid_t pid, void
bend = bp;
*(--bp) = '\0';
- cwdi = p->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
+ cwdi = cwdlock(p);
vp = cwdi->cwdi_cdir;
+ vref(vp);
+ cwdunlock(p);
error = getcwd_common(vp, NULL, &bp, path, len/2, 0, l);
- rw_exit(&cwdi->cwdi_lock);
+ vrele(vp);
if (error)
goto out;
Index: src/sys/kern/uipc_usrreq.c
diff -u src/sys/kern/uipc_usrreq.c:1.194 src/sys/kern/uipc_usrreq.c:1.194.4.1
--- src/sys/kern/uipc_usrreq.c:1.194 Mon Jul 29 09:42:17 2019
+++ src/sys/kern/uipc_usrreq.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: uipc_usrreq.c,v 1.194 2019/07/29 09:42:17 maxv Exp $ */
+/* $NetBSD: uipc_usrreq.c,v 1.194.4.1 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 1998, 2000, 2004, 2008, 2009 The NetBSD Foundation, Inc.
+ * Copyright (c) 1998, 2000, 2004, 2008, 2009, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -96,7 +96,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uipc_usrreq.c,v 1.194 2019/07/29 09:42:17 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uipc_usrreq.c,v 1.194.4.1 2020/01/25 15:54:03 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_compat_netbsd.h"
@@ -1395,6 +1395,7 @@ unp_externalize(struct mbuf *rights, str
{
struct cmsghdr * const cm = mtod(rights, struct cmsghdr *);
struct proc * const p = l->l_proc;
+ struct vnode *rvp = NULL;
file_t **rp;
int error = 0;
@@ -1404,9 +1405,11 @@ unp_externalize(struct mbuf *rights, str
goto noop;
int * const fdp = kmem_alloc(nfds * sizeof(int), KM_SLEEP);
- rw_enter(&p->p_cwdi->cwdi_lock, RW_READER);
+
+ KASSERT(l == curlwp);
/* Make sure the recipient should be able to see the files.. */
+ rvp = cwdrdir();
rp = (file_t **)CMSG_DATA(cm);
for (size_t i = 0; i < nfds; i++) {
file_t * const fp = *rp++;
@@ -1420,15 +1423,15 @@ unp_externalize(struct mbuf *rights, str
* sure it's inside the subtree we're allowed
* to access.
*/
- if (p->p_cwdi->cwdi_rdir != NULL && fp->f_type == DTYPE_VNODE) {
+ if (rvp != NULL && fp->f_type == DTYPE_VNODE) {
vnode_t *vp = fp->f_vnode;
- if ((vp->v_type == VDIR) &&
- !vn_isunder(vp, p->p_cwdi->cwdi_rdir, l)) {
+ if ((vp->v_type == VDIR) && !vn_isunder(vp, rvp, l)) {
error = EPERM;
goto out;
}
}
}
+
restart:
/*
@@ -1506,7 +1509,6 @@ unp_externalize(struct mbuf *rights, str
cm->cmsg_len = CMSG_LEN(0);
rights->m_len = CMSG_SPACE(0);
}
- rw_exit(&p->p_cwdi->cwdi_lock);
kmem_free(fdp, nfds * sizeof(int));
noop:
@@ -1516,6 +1518,10 @@ unp_externalize(struct mbuf *rights, str
KASSERT(cm->cmsg_len <= rights->m_len);
memset(&mtod(rights, char *)[cm->cmsg_len], 0, rights->m_len -
cm->cmsg_len);
+
+ /* Async release please since in the networking code. */
+ if (rvp != NULL)
+ vrele_async(rvp);
return error;
}
Index: src/sys/kern/vfs_cwd.c
diff -u src/sys/kern/vfs_cwd.c:1.4 src/sys/kern/vfs_cwd.c:1.4.62.1
--- src/sys/kern/vfs_cwd.c:1.4 Tue Feb 15 15:54:28 2011
+++ src/sys/kern/vfs_cwd.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: vfs_cwd.c,v 1.4 2011/02/15 15:54:28 pooka Exp $ */
+/* $NetBSD: vfs_cwd.c,v 1.4.62.1 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 2008 The NetBSD Foundation, Inc.
+ * Copyright (c) 2008, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -31,13 +31,14 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.4 2011/02/15 15:54:28 pooka Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cwd.c,v 1.4.62.1 2020/01/25 15:54:03 ad Exp $");
#include <sys/param.h>
#include <sys/atomic.h>
#include <sys/filedesc.h>
#include <sys/proc.h>
#include <sys/vnode.h>
+#include <sys/xcall.h>
static int cwdi_ctor(void *, void *, int);
static void cwdi_dtor(void *, void *);
@@ -64,9 +65,8 @@ cwdinit(void)
struct cwdinfo *copy;
cwdi = pool_cache_get(cwdi_cache, PR_WAITOK);
- copy = curproc->p_cwdi;
- rw_enter(©->cwdi_lock, RW_READER);
+ copy = cwdenter(RW_READER);
cwdi->cwdi_cdir = copy->cwdi_cdir;
if (cwdi->cwdi_cdir)
vref(cwdi->cwdi_cdir);
@@ -78,7 +78,7 @@ cwdinit(void)
vref(cwdi->cwdi_edir);
cwdi->cwdi_cmask = copy->cwdi_cmask;
cwdi->cwdi_refcnt = 1;
- rw_exit(©->cwdi_lock);
+ cwdexit(copy);
return (cwdi);
}
@@ -88,7 +88,7 @@ cwdi_ctor(void *arg, void *obj, int flag
{
struct cwdinfo *cwdi = obj;
- rw_init(&cwdi->cwdi_lock);
+ mutex_init(&cwdi->cwdi_lock, MUTEX_DEFAULT, IPL_NONE);
return 0;
}
@@ -98,7 +98,7 @@ cwdi_dtor(void *arg, void *obj)
{
struct cwdinfo *cwdi = obj;
- rw_destroy(&cwdi->cwdi_lock);
+ mutex_destroy(&cwdi->cwdi_lock);
}
/*
@@ -159,3 +159,120 @@ cwdexec(struct proc *p)
vrele(p->p_cwdi->cwdi_edir);
}
}
+
+/*
+ * Used when curlwp wants to use or update its cwdinfo, and needs to prevent
+ * concurrent changes.
+ *
+ * "op" is either RW_READER or RW_WRITER indicating the kind of lock
+ * required. If a read lock on the cwdinfo is requested, then curlwp must
+ * not block while holding the lock, or the cwdinfo could become stale.
+ * It's okay to block while holding a write lock.
+ */
+struct cwdinfo *
+cwdenter(krw_t op)
+{
+ struct cwdinfo *cwdi = curproc->p_cwdi;
+
+ if (__predict_true(op == RW_READER)) {
+ /*
+ * Disable preemption to hold off the writer side's xcall,
+ * then observe the lock. If it's already taken, we need to
+ * join in the melee. Otherwise we're good to go; keeping
+ * the xcall at bay with kpreempt_disable() will prevent any
+ * changes while the caller is pondering the cwdinfo.
+ */
+ kpreempt_disable();
+ if (__predict_true(mutex_owner(&cwdi->cwdi_lock) == NULL))
+ return cwdi;
+ kpreempt_enable();
+ mutex_enter(&cwdi->cwdi_lock);
+ } else {
+ /*
+ * About to make changes. If there's more than one
+ * reference on the cwdinfo, or curproc has more than one
+ * LWP, then LWPs other than curlwp can also see the
+ * cwdinfo. Run a cross call to get all LWPs out of the
+ * read section. This also acts as a global memory barrier,
+ * meaning we don't need to do anything special with on
+ * the reader side.
+ */
+ mutex_enter(&cwdi->cwdi_lock);
+ if (cwdi->cwdi_refcnt + curproc->p_nlwps > 2)
+ xc_barrier(0);
+ }
+ return cwdi;
+}
+
+/*
+ * Release a lock previously taken with cwdenter().
+ */
+void
+cwdexit(struct cwdinfo *cwdi)
+{
+ struct lwp *l = curlwp;
+
+ KASSERT(cwdi == l->l_proc->p_cwdi);
+
+ if (__predict_true(mutex_owner(&cwdi->cwdi_lock) != l))
+ kpreempt_enable();
+ else
+ mutex_exit(&cwdi->cwdi_lock);
+}
+
+/*
+ * Called when there is a need to inspect some other process' cwdinfo. Used
+ * by procfs and sysctl. This gets you a read lock; the cwdinfo must NOT be
+ * changed.
+ */
+const struct cwdinfo *
+cwdlock(struct proc *p)
+{
+ struct cwdinfo *cwdi = p->p_cwdi;
+
+ mutex_enter(&cwdi->cwdi_lock);
+ return cwdi;
+}
+
+/*
+ * Release a lock acquired with cwdlock().
+ */
+void
+cwdunlock(struct proc *p)
+{
+ struct cwdinfo *cwdi = p->p_cwdi;
+
+ mutex_exit(&cwdi->cwdi_lock);
+}
+
+/*
+ * Get a reference to the current working directory and return it.
+ */
+struct vnode *
+cwdcdir(void)
+{
+ struct cwdinfo *cwdi;
+ struct vnode *vp;
+
+ cwdi = cwdenter(RW_READER);
+ if ((vp = cwdi->cwdi_cdir) != NULL)
+ vref(vp);
+ cwdexit(cwdi);
+ return vp;
+}
+
+/*
+ * Get a reference to the root directory and return it.
+ */
+struct vnode *
+cwdrdir(void)
+{
+ struct cwdinfo *cwdi;
+ struct vnode *vp;
+
+ cwdi = cwdenter(RW_READER);
+ if ((vp = cwdi->cwdi_rdir) != NULL)
+ vref(vp);
+ cwdexit(cwdi);
+ return vp;
+}
Index: src/sys/kern/vfs_getcwd.c
diff -u src/sys/kern/vfs_getcwd.c:1.53.2.3 src/sys/kern/vfs_getcwd.c:1.53.2.4
--- src/sys/kern/vfs_getcwd.c:1.53.2.3 Sun Jan 19 21:19:25 2020
+++ src/sys/kern/vfs_getcwd.c Sat Jan 25 15:54:03 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_getcwd.c,v 1.53.2.3 2020/01/19 21:19:25 ad Exp $ */
+/* $NetBSD: vfs_getcwd.c,v 1.53.2.4 2020/01/25 15:54:03 ad Exp $ */
/*-
* Copyright (c) 1999, 2020 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_getcwd.c,v 1.53.2.3 2020/01/19 21:19:25 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_getcwd.c,v 1.53.2.4 2020/01/25 15:54:03 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -479,7 +479,7 @@ sys___getcwd(struct lwp *l, const struct
char *bp, *bend;
int len = SCARG(uap, length);
int lenused;
- struct cwdinfo *cwdi;
+ struct vnode *dvp;
if (len > MAXPATHLEN * 4)
len = MAXPATHLEN * 4;
@@ -496,11 +496,10 @@ sys___getcwd(struct lwp *l, const struct
* Since each entry takes up at least 2 bytes in the output buffer,
* limit it to N/2 vnodes for an N byte buffer.
*/
- cwdi = l->l_proc->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
- error = getcwd_common(cwdi->cwdi_cdir, NULL, &bp, path,
+ dvp = cwdcdir();
+ error = getcwd_common(dvp, NULL, &bp, path,
len/2, GETCWD_CHECK_ACCESS, l);
- rw_exit(&cwdi->cwdi_lock);
+ vrele(dvp);
if (error)
goto out;
Index: src/sys/kern/vfs_lookup.c
diff -u src/sys/kern/vfs_lookup.c:1.212.4.8 src/sys/kern/vfs_lookup.c:1.212.4.9
--- src/sys/kern/vfs_lookup.c:1.212.4.8 Fri Jan 24 16:05:37 2020
+++ src/sys/kern/vfs_lookup.c Sat Jan 25 15:54:03 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_lookup.c,v 1.212.4.8 2020/01/24 16:05:37 ad Exp $ */
+/* $NetBSD: vfs_lookup.c,v 1.212.4.9 2020/01/25 15:54:03 ad Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.212.4.8 2020/01/24 16:05:37 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.212.4.9 2020/01/25 15:54:03 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_magiclinks.h"
@@ -536,7 +536,6 @@ namei_getstartdir(struct namei_state *st
struct nameidata *ndp = state->ndp;
struct componentname *cnp = state->cnp;
struct cwdinfo *cwdi; /* pointer to cwd state */
- struct lwp *self = curlwp; /* thread doing namei() */
struct vnode *rootdir, *erootdir, *curdir, *startdir;
if (state->root_referenced) {
@@ -547,8 +546,8 @@ namei_getstartdir(struct namei_state *st
state->root_referenced = 0;
}
- cwdi = self->l_proc->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
+ /* NB: we must not block while holding the cwdi read locked. */
+ cwdi = cwdenter(RW_READER);
/* root dir */
if (cwdi->cwdi_rdir == NULL || (cnp->cn_flags & NOCHROOT)) {
@@ -606,7 +605,7 @@ namei_getstartdir(struct namei_state *st
vref(state->ndp->ni_erootdir);
state->root_referenced = 1;
- rw_exit(&cwdi->cwdi_lock);
+ cwdexit(cwdi);
return startdir;
}
Index: src/sys/kern/vfs_mount.c
diff -u src/sys/kern/vfs_mount.c:1.73.2.1 src/sys/kern/vfs_mount.c:1.73.2.2
--- src/sys/kern/vfs_mount.c:1.73.2.1 Fri Jan 17 21:47:35 2020
+++ src/sys/kern/vfs_mount.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: vfs_mount.c,v 1.73.2.1 2020/01/17 21:47:35 ad Exp $ */
+/* $NetBSD: vfs_mount.c,v 1.73.2.2 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 1997-2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 1997-2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -67,7 +67,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.73.2.1 2020/01/17 21:47:35 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,v 1.73.2.2 2020/01/25 15:54:03 ad Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -90,6 +90,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_mount.c,
#include <sys/systm.h>
#include <sys/vfs_syscalls.h>
#include <sys/vnode_impl.h>
+#include <sys/xcall.h>
#include <miscfs/genfs/genfs.h>
#include <miscfs/specfs/specdev.h>
@@ -675,18 +676,23 @@ mount_checkdirs(vnode_t *olddp)
rele2 = NULL;
atomic_inc_uint(&cwdi->cwdi_refcnt);
mutex_exit(proc_lock);
- rw_enter(&cwdi->cwdi_lock, RW_WRITER);
- if (cwdi->cwdi_cdir == olddp) {
- rele1 = cwdi->cwdi_cdir;
- vref(newdp);
- cwdi->cwdi_cdir = newdp;
- }
- if (cwdi->cwdi_rdir == olddp) {
- rele2 = cwdi->cwdi_rdir;
- vref(newdp);
- cwdi->cwdi_rdir = newdp;
+ mutex_enter(&cwdi->cwdi_lock);
+ if (cwdi->cwdi_cdir == olddp ||
+ cwdi->cwdi_rdir == olddp) {
+ /* XXX belongs in vfs_cwd.c, but rump. */
+ xc_barrier(0);
+ if (cwdi->cwdi_cdir == olddp) {
+ rele1 = cwdi->cwdi_cdir;
+ vref(newdp);
+ cwdi->cwdi_cdir = newdp;
+ }
+ if (cwdi->cwdi_rdir == olddp) {
+ rele2 = cwdi->cwdi_rdir;
+ vref(newdp);
+ cwdi->cwdi_rdir = newdp;
+ }
}
- rw_exit(&cwdi->cwdi_lock);
+ mutex_exit(&cwdi->cwdi_lock);
cwdfree(cwdi);
if (rele1 != NULL)
vrele(rele1);
Index: src/sys/kern/vfs_subr.c
diff -u src/sys/kern/vfs_subr.c:1.478.2.2 src/sys/kern/vfs_subr.c:1.478.2.3
--- src/sys/kern/vfs_subr.c:1.478.2.2 Fri Jan 24 16:05:22 2020
+++ src/sys/kern/vfs_subr.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: vfs_subr.c,v 1.478.2.2 2020/01/24 16:05:22 ad Exp $ */
+/* $NetBSD: vfs_subr.c,v 1.478.2.3 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 1997, 1998, 2004, 2005, 2007, 2008, 2019
+ * Copyright (c) 1997, 1998, 2004, 2005, 2007, 2008, 2019, 2020
* The NetBSD Foundation, Inc.
* All rights reserved.
*
@@ -69,7 +69,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_subr.c,v 1.478.2.2 2020/01/24 16:05:22 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_subr.c,v 1.478.2.3 2020/01/25 15:54:03 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -1215,24 +1215,25 @@ set_statvfs_info(const char *onp, int uk
size_t size;
struct statvfs *sfs = &mp->mnt_stat;
int (*fun)(const void *, void *, size_t, size_t *);
+ struct vnode *rvp;
(void)strlcpy(mp->mnt_stat.f_fstypename, vfsname,
sizeof(mp->mnt_stat.f_fstypename));
if (onp) {
- struct cwdinfo *cwdi = l->l_proc->p_cwdi;
fun = (ukon == UIO_SYSSPACE) ? copystr : copyinstr;
- if (cwdi->cwdi_rdir != NULL) {
+ KASSERT(l == curlwp);
+ rvp = cwdrdir();
+ if (rvp != NULL) {
size_t len;
char *bp;
char *path = PNBUF_GET();
bp = path + MAXPATHLEN;
*--bp = '\0';
- rw_enter(&cwdi->cwdi_lock, RW_READER);
- error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp,
+ error = getcwd_common(rvp, rootvnode, &bp,
path, MAXPATHLEN / 2, 0, l);
- rw_exit(&cwdi->cwdi_lock);
+ vrele(rvp);
if (error) {
PNBUF_PUT(path);
return error;
Index: src/sys/kern/vfs_syscalls.c
diff -u src/sys/kern/vfs_syscalls.c:1.539.2.2 src/sys/kern/vfs_syscalls.c:1.539.2.3
--- src/sys/kern/vfs_syscalls.c:1.539.2.2 Sun Jan 19 21:23:36 2020
+++ src/sys/kern/vfs_syscalls.c Sat Jan 25 15:54:03 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: vfs_syscalls.c,v 1.539.2.2 2020/01/19 21:23:36 ad Exp $ */
+/* $NetBSD: vfs_syscalls.c,v 1.539.2.3 2020/01/25 15:54:03 ad Exp $ */
/*-
- * Copyright (c) 2008, 2009, 2019 The NetBSD Foundation, Inc.
+ * Copyright (c) 2008, 2009, 2019, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -70,7 +70,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.539.2.2 2020/01/19 21:23:36 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.539.2.3 2020/01/25 15:54:03 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_fileassoc.h"
@@ -1100,7 +1100,7 @@ int
dostatvfs(struct mount *mp, struct statvfs *sp, struct lwp *l, int flags,
int root)
{
- struct cwdinfo *cwdi = l->l_proc->p_cwdi;
+ struct vnode *rvp;
int error = 0;
/*
@@ -1111,19 +1111,20 @@ dostatvfs(struct mount *mp, struct statv
if (flags == MNT_NOWAIT || flags == MNT_LAZY ||
(flags != MNT_WAIT && flags != 0)) {
memcpy(sp, &mp->mnt_stat, sizeof(*sp));
- goto done;
- }
-
- /* Get the filesystem stats now */
- memset(sp, 0, sizeof(*sp));
- if ((error = VFS_STATVFS(mp, sp)) != 0) {
- return error;
+ rvp = NULL;
+ } else {
+ /* Get the filesystem stats now */
+ memset(sp, 0, sizeof(*sp));
+ if ((error = VFS_STATVFS(mp, sp)) != 0) {
+ return error;
+ }
+ KASSERT(l == curlwp);
+ rvp = cwdrdir();
+ if (rvp == NULL)
+ (void)memcpy(&mp->mnt_stat, sp, sizeof(mp->mnt_stat));
}
- if (cwdi->cwdi_rdir == NULL)
- (void)memcpy(&mp->mnt_stat, sp, sizeof(mp->mnt_stat));
-done:
- if (cwdi->cwdi_rdir != NULL) {
+ if (rvp != NULL) {
size_t len;
char *bp;
char c;
@@ -1131,12 +1132,11 @@ done:
bp = path + MAXPATHLEN;
*--bp = '\0';
- rw_enter(&cwdi->cwdi_lock, RW_READER);
- error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp, path,
+ error = getcwd_common(rvp, rootvnode, &bp, path,
MAXPATHLEN / 2, 0, l);
- rw_exit(&cwdi->cwdi_lock);
if (error) {
PNBUF_PUT(path);
+ vrele(rvp);
return error;
}
len = strlen(bp);
@@ -1161,6 +1161,7 @@ done:
}
}
PNBUF_PUT(path);
+ vrele(rvp);
}
sp->f_flag = mp->mnt_flag & MNT_VISFLAGMASK;
return error;
@@ -1330,7 +1331,6 @@ sys_fchdir(struct lwp *l, const struct s
/* {
syscallarg(int) fd;
} */
- struct proc *p = l->l_proc;
struct cwdinfo *cwdi;
struct vnode *vp, *tdp;
struct mount *mp;
@@ -1370,8 +1370,7 @@ sys_fchdir(struct lwp *l, const struct s
* Disallow changing to a directory not under the process's
* current root directory (if there is one).
*/
- cwdi = p->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_WRITER);
+ cwdi = cwdenter(RW_WRITER);
if (cwdi->cwdi_rdir && !vn_isunder(vp, NULL, l)) {
vrele(vp);
error = EPERM; /* operation not permitted */
@@ -1379,7 +1378,7 @@ sys_fchdir(struct lwp *l, const struct s
vrele(cwdi->cwdi_cdir);
cwdi->cwdi_cdir = vp;
}
- rw_exit(&cwdi->cwdi_lock);
+ cwdexit(cwdi);
out:
fd_putfile(fd);
@@ -1393,7 +1392,6 @@ sys_fchdir(struct lwp *l, const struct s
int
sys_fchroot(struct lwp *l, const struct sys_fchroot_args *uap, register_t *retval)
{
- struct proc *p = l->l_proc;
struct vnode *vp;
file_t *fp;
int error, fd = SCARG(uap, fd);
@@ -1414,8 +1412,7 @@ sys_fchroot(struct lwp *l, const struct
if (error)
goto out;
vref(vp);
-
- change_root(p->p_cwdi, vp, l);
+ change_root(vp);
out:
fd_putfile(fd);
@@ -1432,19 +1429,19 @@ sys_chdir(struct lwp *l, const struct sy
/* {
syscallarg(const char *) path;
} */
- struct proc *p = l->l_proc;
struct cwdinfo *cwdi;
int error;
- struct vnode *vp;
+ struct vnode *vp, *ovp;
- if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
- &vp, l)) != 0)
+ error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE, &vp, l);
+ if (error != 0)
return (error);
- cwdi = p->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_WRITER);
- vrele(cwdi->cwdi_cdir);
+
+ cwdi = cwdenter(RW_WRITER);
+ ovp = cwdi->cwdi_cdir;
cwdi->cwdi_cdir = vp;
- rw_exit(&cwdi->cwdi_lock);
+ cwdexit(cwdi);
+ vrele(ovp);
return (0);
}
@@ -1458,20 +1455,17 @@ sys_chroot(struct lwp *l, const struct s
/* {
syscallarg(const char *) path;
} */
- struct proc *p = l->l_proc;
int error;
struct vnode *vp;
if ((error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_CHROOT,
KAUTH_REQ_SYSTEM_CHROOT_CHROOT, NULL, NULL, NULL)) != 0)
return (error);
- if ((error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE,
- &vp, l)) != 0)
- return (error);
- change_root(p->p_cwdi, vp, l);
-
- return (0);
+ error = chdir_lookup(SCARG(uap, path), UIO_USERSPACE, &vp, l);
+ if (error == 0)
+ change_root(vp);
+ return error;
}
/*
@@ -1479,14 +1473,16 @@ sys_chroot(struct lwp *l, const struct s
* NB: callers need to properly authorize the change root operation.
*/
void
-change_root(struct cwdinfo *cwdi, struct vnode *vp, struct lwp *l)
+change_root(struct vnode *vp)
{
- struct proc *p = l->l_proc;
+ struct cwdinfo *cwdi;
kauth_cred_t ncred;
+ struct lwp *l = curlwp;
+ struct proc *p = l->l_proc;
ncred = kauth_cred_alloc();
- rw_enter(&cwdi->cwdi_lock, RW_WRITER);
+ cwdi = cwdenter(RW_WRITER);
if (cwdi->cwdi_rdir != NULL)
vrele(cwdi->cwdi_rdir);
cwdi->cwdi_rdir = vp;
@@ -1505,7 +1501,7 @@ change_root(struct cwdinfo *cwdi, struct
vref(vp);
cwdi->cwdi_cdir = vp;
}
- rw_exit(&cwdi->cwdi_lock);
+ cwdexit(cwdi);
/* Get a write lock on the process credential. */
proc_crmod_enter();
@@ -4674,21 +4670,15 @@ sys_umask(struct lwp *l, const struct sy
/* {
syscallarg(mode_t) newmask;
} */
- struct proc *p = l->l_proc;
- struct cwdinfo *cwdi;
/*
- * cwdi->cwdi_cmask will be read unlocked elsewhere. What's
- * important is that we serialize changes to the mask. The
- * rw_exit() will issue a write memory barrier on our behalf,
- * and force the changes out to other CPUs (as it must use an
- * atomic operation, draining the local CPU's store buffers).
- */
- cwdi = p->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_WRITER);
- *retval = cwdi->cwdi_cmask;
- cwdi->cwdi_cmask = SCARG(uap, newmask) & ALLPERMS;
- rw_exit(&cwdi->cwdi_lock);
+ * cwdi->cwdi_cmask will be read unlocked elsewhere, and no kind of
+ * serialization with those reads is required. All that's important
+ * is that we get the correct answer for the caller of umask() and
+ * the atomic operation accomplishes.
+ */
+ *retval = atomic_swap_uint(&curproc->p_cwdi->cwdi_cmask,
+ SCARG(uap, newmask) & ALLPERMS);
return (0);
}
@@ -4699,7 +4689,7 @@ dorevoke(struct vnode *vp, kauth_cred_t
struct vattr vattr;
int error, fs_decision;
- vn_lock(vp, LK_SHARED | LK_RETRY);
+ vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
error = VOP_GETATTR(vp, &vattr, cred);
VOP_UNLOCK(vp);
if (error != 0)
Index: src/sys/kern/vfs_vnode.c
diff -u src/sys/kern/vfs_vnode.c:1.105.2.5 src/sys/kern/vfs_vnode.c:1.105.2.6
--- src/sys/kern/vfs_vnode.c:1.105.2.5 Fri Jan 24 16:05:22 2020
+++ src/sys/kern/vfs_vnode.c Sat Jan 25 15:54:03 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_vnode.c,v 1.105.2.5 2020/01/24 16:05:22 ad Exp $ */
+/* $NetBSD: vfs_vnode.c,v 1.105.2.6 2020/01/25 15:54:03 ad Exp $ */
/*-
* Copyright (c) 1997-2011, 2019 The NetBSD Foundation, Inc.
@@ -154,7 +154,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.105.2.5 2020/01/24 16:05:22 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.105.2.6 2020/01/25 15:54:03 ad Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
@@ -912,6 +912,8 @@ vrele_async(vnode_t *vp)
/*
* Vnode reference, where a reference is already held by some other
* object (for example, a file structure).
+ *
+ * NB: we have lockless code sequences that rely on this not blocking.
*/
void
vref(vnode_t *vp)
Index: src/sys/miscfs/procfs/procfs_vnops.c
diff -u src/sys/miscfs/procfs/procfs_vnops.c:1.207 src/sys/miscfs/procfs/procfs_vnops.c:1.207.2.1
--- src/sys/miscfs/procfs/procfs_vnops.c:1.207 Thu Aug 29 06:43:13 2019
+++ src/sys/miscfs/procfs/procfs_vnops.c Sat Jan 25 15:54:04 2020
@@ -1,7 +1,7 @@
-/* $NetBSD: procfs_vnops.c,v 1.207 2019/08/29 06:43:13 hannken Exp $ */
+/* $NetBSD: procfs_vnops.c,v 1.207.2.1 2020/01/25 15:54:04 ad Exp $ */
/*-
- * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc.
+ * Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
@@ -105,7 +105,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.207 2019/08/29 06:43:13 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.207.2.1 2020/01/25 15:54:04 ad Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -557,7 +557,7 @@ static void
procfs_dir(pfstype t, struct lwp *caller, struct proc *target, char **bpp,
char *path, size_t len)
{
- struct cwdinfo *cwdi;
+ const struct cwdinfo *cwdi;
struct vnode *vp, *rvp;
char *bp;
@@ -566,26 +566,25 @@ procfs_dir(pfstype t, struct lwp *caller
* we are interested in to prevent it from disappearing
* before getcwd_common() below.
*/
- rw_enter(&target->p_cwdi->cwdi_lock, RW_READER);
+ cwdi = cwdlock(target);
switch (t) {
case PFScwd:
- vp = target->p_cwdi->cwdi_cdir;
+ vp = cwdi->cwdi_cdir;
break;
case PFSchroot:
- vp = target->p_cwdi->cwdi_rdir;
+ vp = cwdi->cwdi_rdir;
break;
default:
- rw_exit(&target->p_cwdi->cwdi_lock);
+ cwdunlock(target);
return;
}
if (vp != NULL)
vref(vp);
- rw_exit(&target->p_cwdi->cwdi_lock);
+ cwdunlock(target);
- cwdi = caller->l_proc->p_cwdi;
- rw_enter(&cwdi->cwdi_lock, RW_READER);
+ KASSERT(caller == curlwp);
- rvp = cwdi->cwdi_rdir;
+ rvp = cwdrdir();
bp = bpp ? *bpp : NULL;
/*
@@ -598,12 +597,15 @@ procfs_dir(pfstype t, struct lwp *caller
*bpp = bp;
}
vrele(vp);
- rw_exit(&cwdi->cwdi_lock);
+ if (rvp != NULL)
+ vrele(rvp);
return;
}
- if (rvp == NULL)
+ if (rvp == NULL) {
rvp = rootvnode;
+ vref(rvp);
+ }
if (vp == NULL || getcwd_common(vp, rvp, bp ? &bp : NULL, path,
len / 2, 0, caller) != 0) {
if (bpp) {
@@ -617,7 +619,8 @@ procfs_dir(pfstype t, struct lwp *caller
if (vp != NULL)
vrele(vp);
- rw_exit(&cwdi->cwdi_lock);
+ if (rvp != NULL)
+ vrele(rvp);
}
/*
@@ -1646,7 +1649,7 @@ procfs_readlink(void *v)
len = strlen(bp);
} else {
file_t *fp;
- struct vnode *vxp, *vp;
+ struct vnode *vxp, *rvp;
if ((error = procfs_proc_lock(pfs->pfs_pid, &pown, ESRCH)) != 0)
return error;
@@ -1679,14 +1682,13 @@ procfs_readlink(void *v)
if (vxp->v_tag == VT_PROCFS) {
*--bp = '/';
} else {
- rw_enter(&curproc->p_cwdi->cwdi_lock,
- RW_READER);
- vp = curproc->p_cwdi->cwdi_rdir;
- if (vp == NULL)
- vp = rootvnode;
- error = getcwd_common(vxp, vp, &bp, path,
+ if ((rvp = cwdrdir()) == NULL) {
+ rvp = rootvnode;
+ vref(rvp);
+ }
+ error = getcwd_common(vxp, rvp, &bp, path,
MAXPATHLEN / 2, 0, curlwp);
- rw_exit(&curproc->p_cwdi->cwdi_lock);
+ vrele(rvp);
}
if (error)
break;
Index: src/sys/sys/filedesc.h
diff -u src/sys/sys/filedesc.h:1.65 src/sys/sys/filedesc.h:1.65.2.1
--- src/sys/sys/filedesc.h:1.65 Sun Oct 6 07:15:34 2019
+++ src/sys/sys/filedesc.h Sat Jan 25 15:54:04 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: filedesc.h,v 1.65 2019/10/06 07:15:34 mlelstv Exp $ */
+/* $NetBSD: filedesc.h,v 1.65.2.1 2020/01/25 15:54:04 ad Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -168,8 +168,8 @@ typedef struct cwdinfo {
struct vnode *cwdi_cdir; /* current directory */
struct vnode *cwdi_rdir; /* root directory */
struct vnode *cwdi_edir; /* emulation root (if known) */
- krwlock_t cwdi_lock; /* lock on entire struct */
- u_short cwdi_cmask; /* mask for file creation */
+ kmutex_t cwdi_lock; /* lock on entire struct */
+ u_int cwdi_cmask; /* mask for file creation */
u_int cwdi_refcnt; /* reference count */
} cwdinfo_t;
@@ -215,11 +215,17 @@ int pipe1(struct lwp *, int *, int);
int dodup(struct lwp *, int, int, int, register_t *);
void cwd_sys_init(void);
-struct cwdinfo *cwdinit(void);
+struct cwdinfo *cwdinit(void);
void cwdshare(proc_t *);
void cwdunshare(proc_t *);
void cwdfree(struct cwdinfo *);
void cwdexec(struct proc *);
+struct cwdinfo *cwdenter(krw_t);
+void cwdexit(struct cwdinfo *);
+const struct cwdinfo *cwdlock(struct proc *);
+void cwdunlock(struct proc *);
+struct vnode *cwdcdir(void);
+struct vnode *cwdrdir(void);
#define GETCWD_CHECK_ACCESS 0x0001
int getcwd_common(struct vnode *, struct vnode *, char **, char *, int,
Index: src/sys/sys/vfs_syscalls.h
diff -u src/sys/sys/vfs_syscalls.h:1.26 src/sys/sys/vfs_syscalls.h:1.26.2.1
--- src/sys/sys/vfs_syscalls.h:1.26 Thu Sep 26 01:34:16 2019
+++ src/sys/sys/vfs_syscalls.h Sat Jan 25 15:54:04 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_syscalls.h,v 1.26 2019/09/26 01:34:16 christos Exp $ */
+/* $NetBSD: vfs_syscalls.h,v 1.26.2.1 2020/01/25 15:54:04 ad Exp $ */
/*
* Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -82,7 +82,7 @@ int do_sys_quotactl(const char *, const
void do_sys_sync(struct lwp *);
int chdir_lookup(const char *, int, struct vnode **, struct lwp *);
-void change_root(struct cwdinfo *, struct vnode *, struct lwp *);
+void change_root(struct vnode *);
extern const char *const mountcompatnames[];
extern const u_int nmountcompatnames;
