IMPORTANT patch for dazukofs 3.0.1-rc1

diff -rup dazukofs-3.0.1-rc1/inode.c dazukofs-3.0.1-rc1-p1/inode.c
--- dazukofs-3.0.1-rc1/inode.c	2009-04-30 11:53:45.000000000 +0200
+++ dazukofs-3.0.1-rc1-p1/inode.c	2009-05-11 17:35:56.000000000 +0200
@@ -129,36 +129,68 @@ out:
 	return err;
 }
 
-static struct dentry *dazukofs_lookup_one_lower(const char *name,
-						struct dentry *base,
+/* creates a new lower dentry */
+static struct dentry *dazukofs_new_lower_dentry(struct qstr *name,
+						struct dentry *lower_base, 
 						struct nameidata *nd)
 {
-	struct dentry *lower_base;
-	struct vfsmount *lower_mnt;
-	struct vfsmount *vfsmount_save;
-	struct dentry *dentry_save;
+	struct dentry *new_dentry;
+	struct dentry *tmp;
+	struct inode *lower_inode;
+
+	lower_inode = lower_base->d_inode;
+	/* XXX: is this check still necessary? (see __lookup_hash())
+	   This is (hopely) protected by locked upper inode */
+	if (IS_DEADDIR(lower_inode)) {
+		new_dentry = ERR_PTR(-ENOENT);
+		goto out;
+	}
+	tmp = d_alloc(lower_base, name);
+	if (!tmp) {
+		new_dentry = ERR_PTR(-ENOMEM);
+		goto out;
+	}
+	new_dentry = lower_inode->i_op->lookup(lower_inode, tmp, nd);
+	/* lookup() seemingly is allowed to return its own dentry (which 
+	 * may indeed be a dentry or only an error). If so
+	 * we use it and discard ours. Otherwise we use ours */ 
+	if (!new_dentry) 
+		new_dentry = tmp;
+	else 
+		dput(tmp);
+		
+out:		
+	return new_dentry;
+}
+
+
+/* get lower dentry for given name */
+static struct dentry *dazukofs_lookup_one_lower(struct qstr *name, 
+						struct dentry *lower_base,
+						struct vfsmount *lower_mnt)
+{
 	struct dentry *result;
+	struct nameidata nd;
 	int err;
 
-	lower_base = GET_LOWER_DENTRY(base);
-	lower_mnt = GET_LOWER_MNT(base);
+	err = vfs_path_lookup(lower_base, lower_mnt, name->name, 0, &nd);
 
-	vfsmount_save = nd->path.mnt;
-	dentry_save = nd->path.dentry;
-
-	err = vfs_path_lookup(lower_base, lower_mnt, name, nd->flags, nd);
-	if (err) {
-		result = ERR_PTR(err);
-		goto undo;
+	if (!err) {
+		/* inode already exists on disk */
+		result = nd.path.dentry;
+		/* we dont need the mount */
+		mntput(nd.path.mnt);
+		goto out;
 	}
-	/* we dont need the mount */
-	mntput(nd->path.mnt);
-	result = nd->path.dentry;
-undo:
-	nd->path.mnt = vfsmount_save;
-	nd->path.dentry = dentry_save;
-
+	if (err != -ENOENT) { /* this is a REAL error */	
+		result = ERR_PTR(err);
+		goto out;
+	}	
+	/* create a new (lower) dentry */
+	result = dazukofs_new_lower_dentry(name, lower_base, &nd);
+out:
 	return result;
+
 }
 
 
@@ -192,17 +224,19 @@ static struct dentry *dazukofs_lookup(st
 	}
 
 	dentry->d_op = &dazukofs_dops;
-
 	lower_dentry_parent = GET_LOWER_DENTRY(dentry->d_parent);
+	lower_mnt = mntget(GET_LOWER_MNT(dentry->d_parent));
+
+	lower_dentry = dazukofs_lookup_one_lower(&dentry->d_name, 
+						 lower_dentry_parent, 
+						 lower_mnt); 
 
-	lower_dentry = dazukofs_lookup_one_lower(dentry->d_name.name,
-						 dentry->d_parent, nd);
 	if (IS_ERR(lower_dentry)) {
 		err = PTR_ERR(lower_dentry);
+		mntput(lower_mnt);
 		d_drop(dentry);
 		goto out;
 	}
-
 	BUG_ON(!atomic_read(&lower_dentry->d_count));
 
 	SET_DENTRY_INFO(dentry, kmem_cache_zalloc(dazukofs_dentry_info_cachep,
@@ -210,11 +244,9 @@ static struct dentry *dazukofs_lookup(st
 
 	if (!GET_DENTRY_INFO(dentry)) {
 		err = -ENOMEM;
+		mntput(lower_mnt);
 		goto out_dput;
 	}
-
-	lower_mnt = mntget(GET_LOWER_MNT(dentry->d_parent));
-
 	fsstack_copy_attr_atime(dir, lower_dentry_parent->d_inode);
 
 	SET_LOWER_DENTRY(dentry, lower_dentry, lower_mnt);
@@ -228,8 +260,9 @@ static struct dentry *dazukofs_lookup(st
 	}
 
 	err = dazukofs_interpose(lower_dentry, dentry, dir->i_sb, 1);
-	if (err)
+	if (err) 
 		goto out_dput;
+
 	goto out;
 
 out_dput: