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lookup_fastforward(): handle dotdot lookups and give up less often in 

the union mount case.
This commit is contained in:
ad 2020-04-22 21:35:52 +00:00
parent d5cd44f45c
commit 50bfea380a
2 changed files with 36 additions and 22 deletions
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15
sys/kern/vfs_cache.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_cache.c,v 1.139 2020/04/13 19:23:18 ad Exp $ */
/* $NetBSD: vfs_cache.c,v 1.140 2020/04/22 21:35:52 ad Exp $ */
/*-
* Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
@ -172,7 +172,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.139 2020/04/13 19:23:18 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.140 2020/04/22 21:35:52 ad Exp $");
#define __NAMECACHE_PRIVATE
#ifdef _KERNEL_OPT
@ -664,10 +664,17 @@ cache_lookup_linked(struct vnode *dvp, const char *name, size_t namelen,
* before we get its lock.
*
* Note that the two locks can be the same if looking up a dot, for
* example: /usr/bin/.
* example: /usr/bin/. If looking up the parent (..) we can't wait
* on the lock as child -> parent is the wrong direction.
*/
if (*plock != &dvi->vi_nc_lock) {
rw_enter(&dvi->vi_nc_lock, RW_READER);
if (namelen == 2 && name[0] == '.' && name[1] == '.') {
if (!rw_tryenter(&dvi->vi_nc_lock, RW_READER)) {
return false;
}
} else {
rw_enter(&dvi->vi_nc_lock, RW_READER);
}
if (*plock != NULL) {
rw_exit(*plock);
}

43
sys/kern/vfs_lookup.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_lookup.c,v 1.218 2020/04/21 21:42:47 ad Exp $ */
/* $NetBSD: vfs_lookup.c,v 1.219 2020/04/22 21:35:52 ad Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.218 2020/04/21 21:42:47 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.219 2020/04/22 21:35:52 ad Exp $");
#ifdef _KERNEL_OPT
#include "opt_magiclinks.h"
@ -1286,14 +1286,19 @@ lookup_fastforward(struct namei_state *state, struct vnode **searchdir_ret,
}
/*
* Can't deal with dotdot lookups, because it means lock
* order reversal, and there are checks in lookup_once()
* that need to be made. Also check for missing mountpoints.
* Can't deal with DOTDOT lookups if NOCROSSMOUNT or the
* lookup is chrooted.
*/
if ((cnp->cn_flags & ISDOTDOT) != 0 ||
searchdir->v_mount == NULL) {
error = EOPNOTSUPP;
break;
if ((cnp->cn_flags & ISDOTDOT) != 0) {
if ((searchdir->v_vflag & VV_ROOT) != 0 &&
(cnp->cn_flags & NOCROSSMOUNT)) {
error = EOPNOTSUPP;
break;
}
if (ndp->ni_rootdir != rootvnode) {
error = EOPNOTSUPP;
break;
}
}
/*
@ -1309,13 +1314,6 @@ lookup_fastforward(struct namei_state *state, struct vnode **searchdir_ret,
}
}
/* Can't deal with -o union lookups. */
if ((searchdir->v_vflag & VV_ROOT) != 0 &&
(searchdir->v_mount->mnt_flag & MNT_UNION) != 0) {
error = EOPNOTSUPP;
break;
}
/*
* Good, now look for it in cache. cache_lookup_linked()
* will fail if there's nothing there, or if there's no
@ -1329,9 +1327,18 @@ lookup_fastforward(struct namei_state *state, struct vnode **searchdir_ret,
}
KASSERT(plock != NULL && rw_lock_held(plock));
/* Scored a hit. Negative is good too (ENOENT). */
/*
* Scored a hit. Negative is good too (ENOENT). If there's
* a '-o union' mount here, punt and let lookup_once() deal
* with it.
*/
if (foundobj == NULL) {
error = ENOENT;
if ((searchdir->v_vflag & VV_ROOT) != 0 &&
(searchdir->v_mount->mnt_flag & MNT_UNION) != 0) {
error = EOPNOTSUPP;
} else {
error = ENOENT;
}
break;
}