Module Name: src
Committed By: ad
Date: Wed Apr 22 21:35:52 UTC 2020
Modified Files:
src/sys/kern: vfs_cache.c vfs_lookup.c
Log Message:
lookup_fastforward(): handle dotdot lookups and give up less often in
the union mount case.
To generate a diff of this commit:
cvs rdiff -u -r1.139 -r1.140 src/sys/kern/vfs_cache.c
cvs rdiff -u -r1.218 -r1.219 src/sys/kern/vfs_lookup.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_cache.c
diff -u src/sys/kern/vfs_cache.c:1.139 src/sys/kern/vfs_cache.c:1.140
--- src/sys/kern/vfs_cache.c:1.139 Mon Apr 13 19:23:18 2020
+++ src/sys/kern/vfs_cache.c Wed Apr 22 21:35:52 2020
@@ -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, c
* 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);
}
Index: src/sys/kern/vfs_lookup.c
diff -u src/sys/kern/vfs_lookup.c:1.218 src/sys/kern/vfs_lookup.c:1.219
--- src/sys/kern/vfs_lookup.c:1.218 Tue Apr 21 21:42:47 2020
+++ src/sys/kern/vfs_lookup.c Wed Apr 22 21:35:52 2020
@@ -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 *s
}
/*
- * 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 *s
}
}
- /* 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 *s
}
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;
}
