[src/trunk]: src/sys/kern Keep the old vcache node on rekey. Change its key ...

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

details:   https://anonhg.NetBSD.org/src/rev/4ee0df4aec47
branches:  trunk
changeset: 345328:4ee0df4aec47
user:      hannken <hannken%NetBSD.org@localhost>
date:      Thu May 19 14:50:18 2016 +0000

description:
Keep the old vcache node on rekey.  Change its key and remove the
new vcache node now used as placeholder only.

diffstat:

 sys/kern/vfs_vnode.c |  44 ++++++++++++++++++++++++++++++--------------
 1 files changed, 30 insertions(+), 14 deletions(-)

diffs (87 lines):

diff -r ce7c14c98cf5 -r 4ee0df4aec47 sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c      Thu May 19 14:48:28 2016 +0000
+++ b/sys/kern/vfs_vnode.c      Thu May 19 14:50:18 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnode.c,v 1.48 2016/05/19 14:47:33 hannken Exp $   */
+/*     $NetBSD: vfs_vnode.c,v 1.49 2016/05/19 14:50:18 hannken Exp $   */
 
 /*-
  * Copyright (c) 1997-2011 The NetBSD Foundation, Inc.
@@ -116,7 +116,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.48 2016/05/19 14:47:33 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.49 2016/05/19 14:50:18 hannken Exp $");
 
 #define _VFS_VNODE_PRIVATE
 
@@ -1372,6 +1372,8 @@
        new_node->vn_key = new_vcache_key;
 
        mutex_enter(&vcache.lock);
+
+       /* Insert locked new node used as placeholder. */
        node = vcache_hash_lookup(&new_vcache_key, new_hash);
        if (node != NULL) {
                mutex_exit(&vcache.lock);
@@ -1380,6 +1382,8 @@
        }
        SLIST_INSERT_HEAD(&vcache.hashtab[new_hash & vcache.hashmask],
            new_node, vn_hash);
+
+       /* Lock old node. */
        node = vcache_hash_lookup(&old_vcache_key, old_hash);
        KASSERT(node != NULL);
        KASSERT(node->vn_vnode == vp);
@@ -1399,7 +1403,7 @@
 {
        uint32_t old_hash, new_hash;
        struct vcache_key old_vcache_key, new_vcache_key;
-       struct vcache_node *node;
+       struct vcache_node *old_node, *new_node;
 
        old_vcache_key.vk_mount = mp;
        old_vcache_key.vk_key = old_key;
@@ -1412,18 +1416,30 @@
        new_hash = vcache_hash(&new_vcache_key);
 
        mutex_enter(&vcache.lock);
-       node = vcache_hash_lookup(&new_vcache_key, new_hash);
-       KASSERT(node != NULL && node->vn_vnode == NULL);
-       KASSERT(node->vn_key.vk_key_len == new_key_len);
-       node->vn_vnode = vp;
-       node->vn_key = new_vcache_key;
-       node = vcache_hash_lookup(&old_vcache_key, old_hash);
-       KASSERT(node != NULL);
-       KASSERT(node->vn_vnode == NULL);
-       SLIST_REMOVE(&vcache.hashtab[old_hash & vcache.hashmask],
-           node, vcache_node, vn_hash);
+
+       /* Lookup old and new node. */
+       old_node = vcache_hash_lookup(&old_vcache_key, old_hash);
+       KASSERT(old_node != NULL);
+       KASSERT(old_node->vn_vnode == NULL);
+       new_node = vcache_hash_lookup(&new_vcache_key, new_hash);
+       KASSERT(new_node != NULL && new_node->vn_vnode == NULL);
+       KASSERT(new_node->vn_key.vk_key_len == new_key_len);
+
+       /* Rekey old node and put it onto its new hashlist. */
+       old_node->vn_vnode = vp;
+       old_node->vn_key = new_vcache_key;
+       if (old_hash != new_hash) {
+               SLIST_REMOVE(&vcache.hashtab[old_hash & vcache.hashmask],
+                   old_node, vcache_node, vn_hash);
+               SLIST_INSERT_HEAD(&vcache.hashtab[new_hash & vcache.hashmask],
+                   old_node, vn_hash);
+       }
+
+       /* Remove new node used as placeholder. */
+       SLIST_REMOVE(&vcache.hashtab[new_hash & vcache.hashmask],
+           new_node, vcache_node, vn_hash);
        mutex_exit(&vcache.lock);
-       pool_cache_put(vcache.pool, node);
+       pool_cache_put(vcache.pool, new_node);
 }
 
 /*