Add `zpool` flags to control the slot power to drives. This assumes
your SAS or NVMe enclosure supports slot power control via sysfs.
The new `--power` flag is added to `zpool offline|online|clear`:
zpool offline --power <pool> <device> Turn off device slot power
zpool online --power <pool> <device> Turn on device slot power
zpool clear --power <pool> [device] Turn on device slot power
If the ZPOOL_AUTO_POWER_ON_SLOT env var is set, then the '--power'
option is automatically implied for `zpool online` and `zpool clear`
and does not need to be passed.
zpool status also gets a --power option to print the slot power status.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Mart Frauenlob <AllKind@fastest.cc>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#15662
69142125d7