[src/trunk]: src/sys/kern cache_remove(): remove from the vnode list first, s...

[ad <ad%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/44860ab8b748
branches:  trunk
changeset: 746188:44860ab8b748
user:      ad <ad%NetBSD.org@localhost>
date:      Mon Mar 23 20:02:13 2020 +0000

description:
cache_remove(): remove from the vnode list first, so cache_revlookup()
doesn't try to re-activate an entry no longer on the LRU list.

diffstat:

 sys/kern/vfs_cache.c |  27 +++++++++++++++------------
 1 files changed, 15 insertions(+), 12 deletions(-)

diffs (55 lines):

diff -r 711c8232b42b -r 44860ab8b748 sys/kern/vfs_cache.c
--- a/sys/kern/vfs_cache.c      Mon Mar 23 19:45:11 2020 +0000
+++ b/sys/kern/vfs_cache.c      Mon Mar 23 20:02:13 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_cache.c,v 1.133 2020/03/23 19:45:11 ad Exp $       */
+/*     $NetBSD: vfs_cache.c,v 1.134 2020/03/23 20:02:13 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 1.133 2020/03/23 19:45:11 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.134 2020/03/23 20:02:13 ad Exp $");
 
 #define __NAMECACHE_PRIVATE
 #ifdef _KERNEL_OPT
@@ -357,16 +357,10 @@
        SDT_PROBE(vfs, namecache, invalidate, done, ncp,
            0, 0, 0, 0);
 
-       /* First remove from the directory's rbtree. */
-       rb_tree_remove_node(&dvi->vi_nc_tree, ncp);
-
-       /* Then remove from the LRU lists. */
-       mutex_enter(&cache_lru_lock);
-       TAILQ_REMOVE(&cache_lru.list[ncp->nc_lrulist], ncp, nc_lru);
-       cache_lru.count[ncp->nc_lrulist]--;
-       mutex_exit(&cache_lru_lock);
-
-       /* Then remove from the node's list. */
+       /*
+        * Remove from the vnode's list.  This excludes cache_revlookup(),
+        * and then it's safe to remove from the LRU lists.
+        */
        if ((vp = ncp->nc_vp) != NULL) {
                vnode_impl_t *vi = VNODE_TO_VIMPL(vp);
                if (__predict_true(dir2node)) {
@@ -378,6 +372,15 @@
                }
        }
 
+       /* Remove from the directory's rbtree. */
+       rb_tree_remove_node(&dvi->vi_nc_tree, ncp);
+
+       /* Remove from the LRU lists. */
+       mutex_enter(&cache_lru_lock);
+       TAILQ_REMOVE(&cache_lru.list[ncp->nc_lrulist], ncp, nc_lru);
+       cache_lru.count[ncp->nc_lrulist]--;
+       mutex_exit(&cache_lru_lock);
+
        /* Finally, free it. */
        if (ncp->nc_nlen > NCHNAMLEN) {
                size_t sz = offsetof(struct namecache, nc_name[ncp->nc_nlen]);