10499 Multi-modifier protection (MMP)

10499 Multi-modifier protection (MMP)

illumos/illumos-gate@e0f1c0afa46cc84d4b1e40124032a9a87310386e
https://github.com/illumos/illumos-gate/commit/e0f1c0afa46cc84d4b1e40124032a9a87310386e

https://www.illumos.org/issues/10499
  Port the following ZFS commits from ZoL to illumos.
  379ca9cf2 Multi-modifier protection (MMP)
  bbffb59ef Fix multihost stale cache file import
  0d398b256 Do not initiate MMP writes while pool is suspended

Portions contributed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Portions contributed by: Tim Chase <tim@chase2k.com>
Portions contributed by: sanjeevbagewadi <sanjeev.bagewadi@gmail.com>
Portions contributed by: John L. Hammond <john.hammond@intel.com>
Portions contributed by: Giuseppe Di Natale <dinatale2@llnl.gov>
Portions contributed by: Prakash Surya <surya1@llnl.gov>
Author: Olaf Faaland <faaland1@llnl.gov>