This is my initial working version.

There is a bug in boot in this version: subhurd sometimes cannot boot.

1 files changed, 151 insertions, 0 deletions

diff --git a/unionfs/ncache.c b/unionfs/ncache.c
new file mode 100644
index 00000000..4c83ac0e
--- /dev/null
+++ b/unionfs/ncache.c
@@ -0,0 +1,151 @@
+/* Hurd unionfs
+   Copyright (C) 2001, 2002 Free Software Foundation, Inc.
+   Written by Moritz Schulte <moritz@duesseldorf.ccc.de>.
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or * (at your option) any later version.
+ 
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+ 
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+   USA.  */
+
+#define _GNU_SOURCE
+
+#include <hurd/netfs.h>
+#include <error.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include "ncache.h"
+#include "lib.h"
+#include "unionfs.h"
+
+/* The node cache.  */
+ncache_t ncache;
+
+/* Cache size, may be overwritten by the user.  */
+int ncache_size = NCACHE_SIZE;
+
+/* Initialize the node cache, set the maximum number of allowed nodes
+   in the cache to SIZE_MAX.  */
+void
+ncache_init (int size_max)
+{
+  ncache.mru = NULL;
+  ncache.lru = NULL;
+  ncache.size_max = size_max;
+  ncache.size_current = 0;
+  mutex_init (&ncache.lock);
+}
+
+/* Remove the given node NODE from the cache.  */
+static void
+ncache_node_remove (node_t *node)
+{
+  struct netnode *nn = node->nn;
+
+  if (nn->ncache_next)
+    nn->ncache_next->nn->ncache_prev = nn->ncache_prev;
+  if (nn->ncache_prev)
+    nn->ncache_prev->nn->ncache_next = nn->ncache_next;
+  if (ncache.mru == node)
+    ncache.mru = nn->ncache_next;
+  if (ncache.lru == node)
+    ncache.lru = nn->ncache_prev;
+  nn->ncache_next = NULL;
+  nn->ncache_prev = NULL;
+  ncache.size_current--;
+}
+
+void
+ncache_reset (void)
+{
+  node_t *node;
+
+  mutex_lock (&ncache.lock);
+  while ((node = ncache.mru))
+    ncache_node_remove (node);
+  mutex_unlock (&ncache.lock);
+}
+
+/* Lookup the node for the light node LNODE.  If it does not exist
+   anymore in the cache, create a new node.  Store the looked up node
+   in *NODE.  */
+error_t
+ncache_node_lookup (lnode_t *lnode, node_t **node)
+{
+  error_t err = 0;
+  node_t *n;
+
+  if (lnode->node)
+    {
+      debug_msg ("ncache_node_lookup for lnode: %s (found in cache)",
+		 lnode->name);
+      n = lnode->node;
+      netfs_nref (n);
+    }
+  else
+    {
+      debug_msg ("ncache_node_lookup for lnode: %s (newly created)",
+		 lnode->name);
+      err = node_create (lnode, &n);
+    }
+
+  if (! err)
+    {
+      mutex_lock (&n->lock);
+      *node = n;
+    }
+  return err;
+}
+
+/* Add the given node NODE to the node cache; remove
+   least-recently-used nodes, if needed.  */
+void
+ncache_node_add (node_t *node)
+{
+  mutex_lock (&ncache.lock);
+
+  debug_msg ("adding node to cache: %s", node->nn->lnode->name);
+
+  if (ncache.size_max > 0 || ncache.size_current > 0)
+    {
+      if (ncache.mru != node)
+	{
+	  if (node->nn->ncache_next || node->nn->ncache_prev)
+	    /* Node is already in the cache.  */
+	    ncache_node_remove (node);
+	  else
+	    /* Add a reference from the cache.  */
+	    netfs_nref (node);
+	  
+	  node->nn->ncache_next = ncache.mru;
+	  node->nn->ncache_prev = NULL;
+	  if (ncache.mru)
+	    ncache.mru->nn->ncache_prev = node;
+	  if (! ncache.lru)
+	    ncache.lru = node;
+	  ncache.mru = node;
+	  ncache.size_current++;
+	}
+    }
+
+  /* Forget the least used nodes.  */
+  while (ncache.size_current > ncache.size_max)
+    {
+      struct node *lru = ncache.lru;
+      debug_msg ("removing cached node: %s", lru->nn->lnode->name);
+      ncache_node_remove (lru);
+      netfs_nrele (lru);
+    }
+
+  mutex_unlock (&ncache.lock);
+}