zpool: Add slot power control, print power status

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

man/man8/zpool-clear.8

@@ -36,6 +36,7 @@
 .Sh SYNOPSIS
 .Nm zpool
 .Cm clear
+.Op Fl -power
 .Ar pool
 .Oo Ar device Oc Ns …
 .
@@ -52,6 +53,16 @@ Pools with
 enabled which have been suspended cannot be resumed.
 While the pool was suspended, it may have been imported on
 another host, and resuming I/O could result in pool damage.
+.Bl -tag -width Ds
+.It Fl -power
+Power on the devices's slot in the storage enclosure and wait for the device
+to show up before attempting to clear errors.
+This is done on all the devices specified.
+Alternatively, you can set the
+.Sy ZPOOL_AUTO_POWER_ON_SLOT
+environment variable to always enable this behavior.
+Note: This flag currently works on Linux only.
+.El
 .
 .Sh SEE ALSO
 .Xr zdb 8 ,

man/man8/zpool-offline.8

@@ -36,12 +36,13 @@
 .Sh SYNOPSIS
 .Nm zpool
 .Cm offline
-.Op Fl ft
+.Op Fl Sy -power Ns | Ns Op Fl Sy ft
 .Ar pool
 .Ar device Ns …
 .Nm zpool
 .Cm online
-.Op Fl e
+.Op Fl Sy -power
+.Op Fl Sy e
 .Ar pool
 .Ar device Ns …
 .
@@ -50,7 +51,7 @@
 .It Xo
 .Nm zpool
 .Cm offline
-.Op Fl ft
+.Op Fl Sy -power Ns | Ns Op Fl Sy ft
 .Ar pool
 .Ar device Ns …
 .Xc
@@ -60,6 +61,9 @@ While the
 is offline, no attempt is made to read or write to the device.
 This command is not applicable to spares.
 .Bl -tag -width Ds
+.It Fl -power
+Power off the device's slot in the storage enclosure.
+This flag currently works on Linux only
 .It Fl f
 Force fault.
 Instead of offlining the disk, put it into a faulted state.
@@ -73,6 +77,7 @@ Upon reboot, the specified physical device reverts to its previous state.
 .It Xo
 .Nm zpool
 .Cm online
+.Op Fl -power
 .Op Fl e
 .Ar pool
 .Ar device Ns …
@@ -80,6 +85,13 @@ Upon reboot, the specified physical device reverts to its previous state.
 Brings the specified physical device online.
 This command is not applicable to spares.
 .Bl -tag -width Ds
+.It Fl -power
+Power on the device's slot in the storage enclosure and wait for the device
+to show up before attempting to online it.
+Alternatively, you can set the
+.Sy ZPOOL_AUTO_POWER_ON_SLOT
+environment variable to always enable this behavior.
+This flag currently works on Linux only
 .It Fl e
 Expand the device to use all available space.
 If the device is part of a mirror or raidz then all devices must be expanded

man/man8/zpool-status.8

@@ -57,6 +57,8 @@ and the estimated time to completion.
 Both of these are only approximate, because the amount of data in the pool and
 the other workloads on the system can change.
 .Bl -tag -width Ds
+.It Fl -power
+Display vdev enclosure slot power status (on or off).
 .It Fl c Op Ar SCRIPT1 Ns Oo , Ns Ar SCRIPT2 Oc Ns …
 Run a script (or scripts) on each vdev and include the output as a new column
 in the

man/man8/zpool.8

@@ -444,7 +444,7 @@ rpool       14.6G  54.9G      4     55   250K  2.69M
 .Ed
 .
 .Sh ENVIRONMENT VARIABLES
-.Bl -tag -compact -width "ZPOOL_IMPORT_UDEV_TIMEOUT_MS"
+.Bl -tag -compact -width "ZPOOL_STATUS_NON_NATIVE_ASHIFT_IGNORE"
 .It Sy ZFS_ABORT
 Cause
 .Nm
@@ -456,6 +456,23 @@ Use ANSI color in
 and
 .Nm zpool Cm iostat
 output.
+.It Sy ZPOOL_AUTO_POWER_ON_SLOT
+Automatically attempt to turn on the drives enclosure slot power to a drive when
+running the
+.Nm zpool Cm online
+or
+.Nm zpool Cm clear
+commands.
+This has the same effect as passing the
+.Fl -power
+option to those commands.
+.It Sy ZPOOL_POWER_ON_SLOT_TIMEOUT_MS
+The maximum time in milliseconds to wait for a slot power sysfs value
+to return the correct value after writing it.
+For example, after writing "on" to the sysfs enclosure slot power_control file,
+it can take some time for the enclosure to power down the slot and return
+"on" if you read back the 'power_control' value.
+Defaults to 30 seconds (30000ms) if not set.
 .It Sy ZPOOL_IMPORT_PATH
 The search path for devices or files to use with the pool.
 This is a colon-separated list of directories in which