pvscan: add options listlvs listvg checkcomplete

pvscan --cache <dev>
    . read only dev
    . create online file for dev

pvscan --listvg <dev>
    . read only dev
    . list VG using dev

pvscan --listlvs <dev>
    . read only dev
    . list VG using dev
    . list LVs using dev

pvscan --cache --listvg [--checkcomplete] <dev>
    . read only dev
    . create online file for dev
    . list VG using dev
    . [check online files and report if VG is complete]

pvscan --cache --listlvs [--checkcomplete] <dev>
    . read only dev
    . create online file for dev
    . list VG using dev
    . list LVs using dev
    . [check online files and report if VG is complete]
    . [check online files and report if LVs are complete]

[--vgonline]
can be used with --checkcomplete, to enable use of a vg online
file.  This results in only the first pvscan command to see
the complete VG to report 'VG complete', and others will report
'VG finished'.  This allows the caller to easily run a single
activation of the VG.

[--udevoutput]
can be used with --cache --listvg --checkcomplete, to enable
an output mode that prints LVM_VG_NAME_COMPLETE='vgname' that
a udev rule can import, and prevents other output from the
command (other output causes udev to ignore the command.)

The list of complete LVs is meant to be passed to lvchange -aay,
or the complete VG used with vgchange -aay.

When --checkcomplete is used, lvm assumes that that the output
will be used to trigger event-based autoactivation, so the pvscan
does nothing if event_activation=0 and --checkcomplete is used.

Example of listlvs
------------------

$ lvs -a vg -olvname,devices
  LV     Devices
  lv_a   /dev/loop0(0)
  lv_ab  /dev/loop0(1),/dev/loop1(1)
  lv_abc /dev/loop0(3),/dev/loop1(3),/dev/loop2(1)
  lv_b   /dev/loop1(0)
  lv_c   /dev/loop2(0)

$ pvscan --cache --listlvs --checkcomplete /dev/loop0
  pvscan[35680] PV /dev/loop0 online, VG vg incomplete (need 2).
  VG vg incomplete
  LV vg/lv_a complete
  LV vg/lv_ab incomplete
  LV vg/lv_abc incomplete

$ pvscan --cache --listlvs --checkcomplete /dev/loop1
  pvscan[35681] PV /dev/loop1 online, VG vg incomplete (need 1).
  VG vg incomplete
  LV vg/lv_b complete
  LV vg/lv_ab complete
  LV vg/lv_abc incomplete

$ pvscan --cache --listlvs --checkcomplete /dev/loop2
  pvscan[35682] PV /dev/loop2 online, VG vg is complete.
  VG vg complete
  LV vg/lv_c complete
  LV vg/lv_abc complete

Example of listvg
-----------------

$ pvscan --cache --listvg --checkcomplete /dev/loop0
  pvscan[35684] PV /dev/loop0 online, VG vg incomplete (need 2).
  VG vg incomplete

$ pvscan --cache --listvg --checkcomplete /dev/loop1
  pvscan[35685] PV /dev/loop1 online, VG vg incomplete (need 1).
  VG vg incomplete

$ pvscan --cache --listvg --checkcomplete /dev/loop2
  pvscan[35686] PV /dev/loop2 online, VG vg is complete.
  VG vg complete

1 files changed, 28 insertions, 2 deletions

diff --git a/tools/command-lines.in b/tools/command-lines.in
index e63b2bcc3..332ad8a3b 100644
--- a/tools/command-lines.in
+++ b/tools/command-lines.in
@@ -1634,11 +1634,37 @@ DESC: Display PV information.
 
 pvscan --cache_long
 OO: --ignorelockingfailure, --reportformat ReportFmt,
---activate ay, --major Number, --minor Number, --noudevsync
+--major Number, --minor Number, --noudevsync
 OP: PV|String ...
 IO: --background
 ID: pvscan_cache
-DESC: Autoactivate a VG when all PVs are online.
+DESC: Record that a PV is online or offline.
+
+pvscan --cache_long --activate ay
+OO: --ignorelockingfailure, --reportformat ReportFmt,
+--major Number, --minor Number, --noudevsync
+OP: PV|String ...
+IO: --background
+ID: pvscan_cache
+DESC: Record that a PV is online and autoactivate the VG if complete.
+
+pvscan --cache_long --listvg PV
+OO: --ignorelockingfailure, --checkcomplete, --vgonline, --udevoutput
+ID: pvscan_cache
+DESC: Record that a PV is online and list the VG using the PV.
+
+pvscan --cache_long --listlvs PV
+OO: --ignorelockingfailure, --checkcomplete, --vgonline
+ID: pvscan_cache
+DESC: Record that a PV is online and list LVs using the PV.
+
+pvscan --listlvs PV
+ID: pvscan_cache
+DESC: List LVs using the PV.
+
+pvscan --listvg PV
+ID: pvscan_cache
+DESC: List the VG using the PV.
 
 ---