xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/uberblock_impl.h (revision 4a7ceb24cfcc0a97f96d86cfe5852ae445b50e57)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #ifndef _SYS_UBERBLOCK_IMPL_H
27 #define	_SYS_UBERBLOCK_IMPL_H
28 
29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
30 
31 #include <sys/uberblock.h>
32 
33 #ifdef	__cplusplus
34 extern "C" {
35 #endif
36 
37 /*
38  * The uberblock version is incremented whenever an incompatible on-disk
39  * format change is made to the SPA, DMU, or ZAP.
40  *
41  * Note: the first two fields should never be moved.  When a storage pool
42  * is opened, the uberblock must be read off the disk before the version
43  * can be checked.  If the ub_version field is moved, we may not detect
44  * version mismatch.  If the ub_magic field is moved, applications that
45  * expect the magic number in the first word won't work.
46  */
47 #define	UBERBLOCK_MAGIC		0x00bab10c		/* oo-ba-bloc!	*/
48 #define	UBERBLOCK_SHIFT		10			/* up to 1K	*/
49 
50 struct uberblock {
51 	uint64_t	ub_magic;	/* UBERBLOCK_MAGIC		*/
52 	uint64_t	ub_version;	/* SPA_VERSION			*/
53 	uint64_t	ub_txg;		/* txg of last sync		*/
54 	uint64_t	ub_guid_sum;	/* sum of all vdev guids	*/
55 	uint64_t	ub_timestamp;	/* UTC time of last sync	*/
56 	blkptr_t	ub_rootbp;	/* MOS objset_phys_t		*/
57 };
58 
59 #ifdef	__cplusplus
60 }
61 #endif
62 
63 #endif	/* _SYS_UBERBLOCK_IMPL_H */
64