include/sys/uberblock_impl.h

   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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2016, 2017 by Delphix. All rights reserved.
  24  */
  25
  26 #ifndef _SYS_UBERBLOCK_IMPL_H
  27 #define _SYS_UBERBLOCK_IMPL_H
  28
  29 #include <sys/uberblock.h>
  30
  31 #ifdef  __cplusplus
  32 extern "C" {
  33 #endif
  34
  35 /*
  36  * The uberblock version is incremented whenever an incompatible on-disk
  37  * format change is made to the SPA, DMU, or ZAP.
  38  *
  39  * Note: the first two fields should never be moved.  When a storage pool
  40  * is opened, the uberblock must be read off the disk before the version
  41  * can be checked.  If the ub_version field is moved, we may not detect
  42  * version mismatch.  If the ub_magic field is moved, applications that
  43  * expect the magic number in the first word won't work.
  44  */
  45 #define UBERBLOCK_MAGIC         0x00bab10c              /* oo-ba-bloc!  */
  46 #define UBERBLOCK_SHIFT         10                      /* up to 1K     */
  47 #define MMP_MAGIC               0xa11cea11              /* all-see-all  */
  48
  49 struct uberblock {
  50         uint64_t        ub_magic;       /* UBERBLOCK_MAGIC              */
  51         uint64_t        ub_version;     /* SPA_VERSION                  */
  52         uint64_t        ub_txg;         /* txg of last sync             */
  53         uint64_t        ub_guid_sum;    /* sum of all vdev guids        */
  54         uint64_t        ub_timestamp;   /* UTC time of last sync        */
  55         blkptr_t        ub_rootbp;      /* MOS objset_phys_t            */
  56
  57         /* highest SPA_VERSION supported by software that wrote this txg */
  58         uint64_t        ub_software_version;
  59
  60         /* Maybe missing in uberblocks we read, but always written */
  61         uint64_t        ub_mmp_magic;   /* MMP_MAGIC                    */
  62         uint64_t        ub_mmp_delay;   /* nanosec since last MMP write */
  63         uint64_t        ub_mmp_seq;     /* reserved for sequence number */
  64
  65         /*
  66          * ub_checkpoint_txg indicates two things about the current uberblock:
  67          *
  68          * 1] If it is not zero then this uberblock is a checkpoint. If it is
  69          *    zero, then this uberblock is not a checkpoint.
  70          *
  71          * 2] On checkpointed uberblocks, the value of ub_checkpoint_txg is
  72          *    the ub_txg that the uberblock had at the time we moved it to
  73          *    the MOS config.
  74          *
  75          * The field is set when we checkpoint the uberblock and continues to
  76          * hold that value even after we've rewound (unlike the ub_txg that
  77          * is reset to a higher value).
  78          *
  79          * Besides checks used to determine whether we are reopening the
  80          * pool from a checkpointed uberblock [see spa_ld_select_uberblock()],
  81          * the value of the field is used to determine which ZIL blocks have
  82          * been allocated according to the ms_sm when we are rewinding to a
  83          * checkpoint. Specifically, if blk_birth > ub_checkpoint_txg, then
  84          * the ZIL block is not allocated [see uses of spa_min_claim_txg()].
  85          */
  86         uint64_t        ub_checkpoint_txg;
  87 };
  88
  89 #ifdef  __cplusplus
  90 }
  91 #endif
  92
  93 #endif  /* _SYS_UBERBLOCK_IMPL_H */