mirror_zfs/include/sys/uberblock_impl.h
Serapheim Dimitropoulos 829f9251cf OpenZFS 8491 - uberblock on-disk padding to reserve space for smoothly merging zpool checkpoint & MMP in ZFS
The zpool checkpoint feature in DxOS added a new field in the uberblock.
The Multi-Modifier Protection Pull Request from ZoL adds three new fields
in the uberblock (Reference: https://github.com/zfsonlinux/zfs/pull/6279).
As these two changes come from two different sources and once upstreamed
and deployed will introduce an incompatibility with each other we want
to upstream a change that will reserve the padding for both of them so
integration goes smoothly and everyone gets both features.

Porting Notes: Preserved MMP comments in uberblock struct.

Authored by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Olaf Faaland <faaland1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

OpenZFS-issue: https://www.illumos.org/issues/8491
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d84fa5f
Closes #6390
2017-07-24 13:47:51 -04:00

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C

/*
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/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2017 by Delphix. All rights reserved.
*/
#ifndef _SYS_UBERBLOCK_IMPL_H
#define _SYS_UBERBLOCK_IMPL_H
#include <sys/uberblock.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* The uberblock version is incremented whenever an incompatible on-disk
* format change is made to the SPA, DMU, or ZAP.
*
* Note: the first two fields should never be moved. When a storage pool
* is opened, the uberblock must be read off the disk before the version
* can be checked. If the ub_version field is moved, we may not detect
* version mismatch. If the ub_magic field is moved, applications that
* expect the magic number in the first word won't work.
*/
#define UBERBLOCK_MAGIC 0x00bab10c /* oo-ba-bloc! */
#define UBERBLOCK_SHIFT 10 /* up to 1K */
#define MMP_MAGIC 0xa11cea11 /* all-see-all */
struct uberblock {
uint64_t ub_magic; /* UBERBLOCK_MAGIC */
uint64_t ub_version; /* SPA_VERSION */
uint64_t ub_txg; /* txg of last sync */
uint64_t ub_guid_sum; /* sum of all vdev guids */
uint64_t ub_timestamp; /* UTC time of last sync */
blkptr_t ub_rootbp; /* MOS objset_phys_t */
/* highest SPA_VERSION supported by software that wrote this txg */
uint64_t ub_software_version;
/* Maybe missing in uberblocks we read, but always written */
uint64_t ub_mmp_magic; /* MMP_MAGIC */
uint64_t ub_mmp_delay; /* nanosec since last MMP write */
uint64_t ub_mmp_seq; /* reserved for sequence number */
uint64_t ub_checkpoint_txg;
};
#ifdef __cplusplus
}
#endif
#endif /* _SYS_UBERBLOCK_IMPL_H */