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1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3  *  GRUB  --  GRand Unified Bootloader
4  *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
5  */
6 /*
7  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
8  * Use is subject to license terms.
9  */
10 
11 #ifndef _SYS_UBERBLOCK_IMPL_H
12 #define	_SYS_UBERBLOCK_IMPL_H
13 
14 #define UBMAX(a, b) ((a) > (b) ? (a) : (b))
15 
16 /*
17  * The uberblock version is incremented whenever an incompatible on-disk
18  * format change is made to the SPA, DMU, or ZAP.
19  *
20  * Note: the first two fields should never be moved.  When a storage pool
21  * is opened, the uberblock must be read off the disk before the version
22  * can be checked.	If the ub_version field is moved, we may not detect
23  * version mismatch.  If the ub_magic field is moved, applications that
24  * expect the magic number in the first word won't work.
25  */
26 #define	UBERBLOCK_MAGIC		0x00bab10c		/* oo-ba-bloc!	*/
27 #define	UBERBLOCK_SHIFT		10			/* up to 1K	*/
28 
29 typedef struct uberblock {
30 	uint64_t	ub_magic;	/* UBERBLOCK_MAGIC		*/
31 	uint64_t	ub_version;	/* ZFS_VERSION			*/
32 	uint64_t	ub_txg;		/* txg of last sync		*/
33 	uint64_t	ub_guid_sum;	/* sum of all vdev guids	*/
34 	uint64_t	ub_timestamp;	/* UTC time of last sync	*/
35 	blkptr_t	ub_rootbp;	/* MOS objset_phys_t		*/
36 } uberblock_t;
37 
38 #define	VDEV_UBERBLOCK_SHIFT(as)	UBMAX(as, UBERBLOCK_SHIFT)
39 #define	UBERBLOCK_SIZE(as)		(1ULL << VDEV_UBERBLOCK_SHIFT(as))
40 
41 /* Number of uberblocks that can fit in the ring at a given ashift */
42 #define UBERBLOCK_COUNT(as) (VDEV_UBERBLOCK_RING >> VDEV_UBERBLOCK_SHIFT(as))
43 
44 #endif	/* _SYS_UBERBLOCK_IMPL_H */
45