include/zfs/uberblock_impl.h

   1 /*
   2  *  GRUB  --  GRand Unified Bootloader
   3  *  Copyright (C) 1999,2000,2001,2002,2003,2004  Free Software Foundation, Inc.
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19 /*
  20  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  21  * Use is subject to license terms.
  22  */
  23
  24 #ifndef _SYS_UBERBLOCK_IMPL_H
  25 #define _SYS_UBERBLOCK_IMPL_H
  26
  27 #define UBMAX(a, b) ((a) > (b) ? (a) : (b))
  28
  29 /*
  30  * The uberblock version is incremented whenever an incompatible on-disk
  31  * format change is made to the SPA, DMU, or ZAP.
  32  *
  33  * Note: the first two fields should never be moved.  When a storage pool
  34  * is opened, the uberblock must be read off the disk before the version
  35  * can be checked.      If the ub_version field is moved, we may not detect
  36  * version mismatch.  If the ub_magic field is moved, applications that
  37  * expect the magic number in the first word won't work.
  38  */
  39 #define UBERBLOCK_MAGIC         0x00bab10c              /* oo-ba-bloc!  */
  40 #define UBERBLOCK_SHIFT         10                      /* up to 1K     */
  41
  42 typedef struct uberblock {
  43         uint64_t        ub_magic;       /* UBERBLOCK_MAGIC              */
  44         uint64_t        ub_version;     /* ZFS_VERSION                  */
  45         uint64_t        ub_txg;         /* txg of last sync             */
  46         uint64_t        ub_guid_sum;    /* sum of all vdev guids        */
  47         uint64_t        ub_timestamp;   /* UTC time of last sync        */
  48         blkptr_t        ub_rootbp;      /* MOS objset_phys_t            */
  49 } uberblock_t;
  50
  51 #define VDEV_UBERBLOCK_SHIFT(as)        UBMAX(as, UBERBLOCK_SHIFT)
  52 #define UBERBLOCK_SIZE(as)              (1ULL << VDEV_UBERBLOCK_SHIFT(as))
  53
  54 /* Number of uberblocks that can fit in the ring at a given ashift */
  55 #define UBERBLOCK_COUNT(as) (VDEV_UBERBLOCK_RING >> VDEV_UBERBLOCK_SHIFT(as))
  56
  57 #endif  /* _SYS_UBERBLOCK_IMPL_H */