Use kstat to get a more accurate count of uberblock updates.
Using a loop with zdb can potentially miss some uberblocks.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6407Closes#6419
ZFS is an advanced file system and volume manager which was originally
developed for Solaris and is now maintained by the Illumos community.
ZFS on Linux, which is also known as ZoL, is currently feature complete. It
includes fully functional and stable SPA, DMU, ZVOL, and ZPL layers. And it's native!