Please welcome ZFS - The last word in file systems.

ZFS file system was ported from OpenSolaris operating system. The code in under
CDDL license.

I'd like to thank all SUN developers that created this great piece of software.

Supported by:	Wheel LTD (http://www.wheel.pl/)
Supported by:	The FreeBSD Foundation (http://www.freebsdfoundation.org/)
Supported by:	Sentex (http://www.sentex.net/)

1 files changed, 107 insertions, 0 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/unique.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/unique.c
new file mode 100644
index 0000000..b52e729
--- /dev/null
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/unique.c
@@ -0,0 +1,107 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <sys/zfs_context.h>
+#include <sys/avl.h>
+#include <sys/unique.h>
+
+static avl_tree_t unique_avl;
+static kmutex_t unique_mtx;	/* Lock never initialized. */
+SX_SYSINIT(unique, &unique_mtx, "unique lock");
+
+typedef struct unique {
+	avl_node_t un_link;
+	uint64_t un_value;
+} unique_t;
+
+#define	UNIQUE_MASK ((1ULL << UNIQUE_BITS) - 1)
+
+static int
+unique_compare(const void *a, const void *b)
+{
+	const unique_t *una = a;
+	const unique_t *unb = b;
+
+	if (una->un_value < unb->un_value)
+		return (-1);
+	if (una->un_value > unb->un_value)
+		return (+1);
+	return (0);
+}
+
+void
+unique_init(void)
+{
+	avl_create(&unique_avl, unique_compare,
+	    sizeof (unique_t), offsetof(unique_t, un_link));
+}
+
+uint64_t
+unique_create(void)
+{
+	return (unique_insert(0));
+}
+
+uint64_t
+unique_insert(uint64_t value)
+{
+	avl_index_t idx;
+	unique_t *un = kmem_alloc(sizeof (unique_t), KM_SLEEP);
+
+	un->un_value = value;
+
+	mutex_enter(&unique_mtx);
+	while (un->un_value == 0 || un->un_value & ~UNIQUE_MASK ||
+	    avl_find(&unique_avl, un, &idx)) {
+		mutex_exit(&unique_mtx);
+		(void) random_get_pseudo_bytes((void*)&un->un_value,
+		    sizeof (un->un_value));
+		un->un_value &= UNIQUE_MASK;
+		mutex_enter(&unique_mtx);
+	}
+
+	avl_insert(&unique_avl, un, idx);
+	mutex_exit(&unique_mtx);
+
+	return (un->un_value);
+}
+
+void
+unique_remove(uint64_t value)
+{
+	unique_t un_tofind;
+	unique_t *un;
+
+	un_tofind.un_value = value;
+	mutex_enter(&unique_mtx);
+	un = avl_find(&unique_avl, &un_tofind, NULL);
+	if (un != NULL) {
+		avl_remove(&unique_avl, un);
+		kmem_free(un, sizeof (unique_t));
+	}
+	mutex_exit(&unique_mtx);
+}