MFC r322241: MFV r322240: 8491 uberblock on-disk padding to reserve space for smoothly merging zpool checkpoint & MMP in ZFS
illumos/illumos-gate@79c2b812ee2010ebf20fdd92dc5f06b59000a94c
https://github.com/illumos/illumos-gate/commit/79c2b812ee2010ebf20fdd92dc5f06b59000a94c
https://www.illumos.org/issues/8491
The zpool checkpoint feature in DxOS added a new field in the uberblock. The Multi-Modifier Protection Pull Request from ZoL adds two 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.
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>
Author: Serapheim Dimitropoulos <serapheim@delphix.com>