Module Name: src
Committed By: ad
Date: Sun Mar 22 01:58:22 UTC 2020
Modified Files:
src/sys/kern [ad-namecache]: vfs_cache.c
Log Message:
- rb_tree_insert_node() refuses to insert duplicate nodes. It always
returns a pointer to the current node in the tree for the given key.
Therefore the call to rb_tree_lookup_node() in cache_enter() is not
needed.
- Adjust a comment and move some code for clarity.
To generate a diff of this commit:
cvs rdiff -u -r1.126.2.15 -r1.126.2.16 src/sys/kern/vfs_cache.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:1.126.2.15 src/sys/kern/vfs_cache.c:1.126.2.16
--- src/sys/kern/vfs_cache.c:1.126.2.15 Sun Mar 22 00:34:31 2020
+++ src/sys/kern/vfs_cache.c Sun Mar 22 01:58:22 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_cache.c,v 1.126.2.15 2020/03/22 00:34:31 ad Exp $ */
+/* $NetBSD: vfs_cache.c,v 1.126.2.16 2020/03/22 01:58:22 ad Exp $ */
/*-
* Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
@@ -171,7 +171,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.126.2.15 2020/03/22 00:34:31 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.126.2.16 2020/03/22 01:58:22 ad Exp $");
#define __NAMECACHE_PRIVATE
#ifdef _KERNEL_OPT
@@ -416,8 +416,6 @@ cache_lookup_entry(struct vnode *dvp, co
* Search the RB tree for the key. This is an inlined lookup
* tailored for exactly what's needed here (64-bit key and so on)
* that is quite a bit faster than using rb_tree_find_node().
- * Elsewhere during entry/removal the usual functions are used as it
- * doesn't matter there.
*/
for (;;) {
if (__predict_false(RB_SENTINEL_P(node))) {
@@ -525,6 +523,9 @@ cache_lookup(struct vnode *dvp, const ch
return false;
}
+ /* Compute the key up front - don't need the lock. */
+ key = cache_key(name, namelen);
+
/* Could the entry be purged below? */
if ((cnflags & ISLASTCN) != 0 &&
((cnflags & MAKEENTRY) == 0 || nameiop == CREATE)) {
@@ -533,9 +534,6 @@ cache_lookup(struct vnode *dvp, const ch
op = RW_READER;
}
- /* Compute the key up front - don't need the lock. */
- key = cache_key(name, namelen);
-
/* Now look for the name. */
rw_enter(&dvi->vi_nc_lock, op);
ncp = cache_lookup_entry(dvp, name, namelen, key);
@@ -890,18 +888,20 @@ cache_enter(struct vnode *dvp, struct vn
/*
* Insert to the directory. Concurrent lookups in the same
* directory may race for a cache entry. There can also be hash
- * value collisions. If there's a entry there already, free it.
+ * value collisions. If there's a entry there already, purge it.
*/
rw_enter(&dvi->vi_nc_lock, RW_WRITER);
- oncp = rb_tree_find_node(&dvi->vi_nc_tree, &ncp->nc_key);
- if (oncp) {
+ oncp = rb_tree_insert_node(&dvi->vi_nc_tree, ncp);
+ if (oncp != ncp) {
+ KASSERT(oncp->nc_key == ncp->nc_key);
KASSERT(oncp->nc_nlen == ncp->nc_nlen);
if (cache_namecmp(oncp, name, namelen)) {
COUNT(ncs_collisions);
}
cache_remove(oncp, true);
+ oncp = rb_tree_insert_node(&dvi->vi_nc_tree, ncp);
+ KASSERT(oncp == ncp);
}
- rb_tree_insert_node(&dvi->vi_nc_tree, ncp);
/* Then insert to the vnode. */
if (vp == NULL) {
