Misc: Make get_pv_list_for_lv() available to more than just RAID

The function 'get_pv_list_for_lv' will assemble all the PVs that are
used by the specified LV.  It uses 'for_each_sub_lv' to traverse all
of the sub-lvs which may compose it.
Thin: Make 'lv_is_on_pv(s)' work with thin types

The pool metadata LV must be accounted for when determining what PVs
are in a thin-pool.  The pool LV must also be accounted for when
checking thin volumes.

This is a prerequisite for pvmove working with thin types.
pvmove: Add support for RAID, mirror, and thin

This patch allows pvmove to operate on RAID, mirror and thin LVs.
The key component is the ability to avoid moving a RAID or mirror
sub-LV onto a PV that already has another RAID sub-LV on it.
(e.g. Avoid placing both images of a RAID1 LV on the same PV.)

Top-level LVs are processed to determine which PVs to avoid for
the sake of redundancy, while bottom-level LVs are processed
to determine which segments/extents to move.

This approach does have some drawbacks.  By eliminating whole PVs
from the allocation list, we might miss the opportunity to perform
pvmove in some senarios.  For example, if we have 3 devices and
a linear uses half of the first, a RAID1 uses half of the first and
half of the second, and a linear uses half of the third (FIGURE 1);
we should be able to pvmove the first device (FIGURE 2).
	FIGURE 1:
        [ linear ] [ -RAID- ] [ linear ]
        [ -RAID- ] [        ] [        ]

	FIGURE 2:
        [  moved ] [ -RAID- ] [ linear ]
        [  moved ] [ linear ] [ -RAID- ]
However, the approach we are using would eliminate the second
device from consideration and would leave us with too little space
for allocation.  In these situations, the user does have the ability
to specify LVs and move them one at a time.
pvmove: Ability to move thin volumes

The previous commit was missing the code to allow moving thin
volumes.
misc: make lv_is_on_pv use for_each_sub_lv to walk LV tree

Make lv_is_on_pv use for_each_sub_lv to walk the LV tree.  This
reduces code duplication.
test: add vg-name-from-env

vg name should come from env var LVM_VG_NAME
for commands that take vg name and lv name,
but vg name is not specified on command line.
test: add process-each-duplicate-vgnames

Test that vgs shows both vgs when two vgs
exist with the same name but different uuids.
test: add process-each-vg and process-each-lv

These test the toollib functions that select
vgs/lvs to process based on command line args:
empty, vg name(s), lv names(s), vg tag(s),
lv tags(s), and combinations of all.
thin: support lvchange for data and metadata

Support lvchange operation on stacked thin pool data and metadata
volumes.
udev: inform lvmetad about lost PV label

In stacked environment where we have a PV layered on top of a
snapshot LV and then removing the LV, lvmetad still keeps information
about the PV:

[0] raw/~ $ pvcreate /dev/sda
  Physical volume "/dev/sda" successfully created
[0] raw/~ $ vgcreate vg /dev/sda
  Volume group "vg" successfully created
[0] raw/~ $ lvcreate -L32m vg
  Logical volume "lvol0" created
[0] raw/~ $ lvcreate -L32m -s vg/lvol0
  Logical volume "lvol1" created
[0] raw/~ $ pvcreate /dev/vg/lvol1
  Physical volume "/dev/vg/lvol1" successfully created
[0] raw/~ $ lvremove -ff vg/lvol1
  Logical volume "lvol1" successfully removed
[0] raw/~ $ pvs
  No device found for PV BdNlu2-7bHV-XcIp-mFFC-PPuR-ef6K-yffdzO.
  PV         VG         Fmt  Attr PSize   PFree
  /dev/sda   vg         lvm2 a--  124.00m 92.00m
[0] raw/~ $ pvscan --cache --major 253 --minor 3
  Device 253:3 not found. Cleared from lvmetad cache.

This is because of the reactivation that is done just before
snapshot removal as part of the process (vg/lvol1 from the example above).
This causes a CHANGE event to be generated, but any scan done
on the LV does not see the original data anymore (in this case
the stacked PV label on top) and consequently the ID_FS_TYPE="LVM2_member"
(provided by blkid scan) is not stored in udev db anymore for the LV.
Consequently, the pvscan --cache is not run anymore as the dev is not
identified as LVM PV by the "LVM2_member" id - lvmetad loses this info
and still keeps records about the PV.

We can run into a very similar problem with erasing the PV label directly:

[0] raw/~ $ lvcreate -L32m vg
  Logical volume "lvol0" created
[0] raw/~ $ pvcreate /dev/vg/lvol0
  Physical volume "/dev/vg/lvol0" successfully created
[0] raw/~ $ dd if=/dev/zero of=/dev/vg/lvol0 bs=1M
dd: error writing '/dev/vg/lvol0': No space left on device
33+0 records in
32+0 records out
33554432 bytes (34 MB) copied, 0.380921 s, 88.1 MB/s
[0] raw/~ $ pvs
  PV            VG         Fmt  Attr PSize   PFree
  /dev/sda      vg         lvm2 a--  124.00m 92.00m
  /dev/vg/lvol0            lvm2 a--   32.00m 32.00m
[0] raw/~ $ pvscan --cache --major 253 --minor 2
  No PV label found on /dev/vg/lvol0.

This patch adds detection of this change from ID_FS_LABEL="LVM2_member"
to ID_FS_LABEL="<whatever_else>" and hence informing the lvmetad
about PV being gone.
WHATS_NEW: for 4d3b5724e0b51782000a45027de00e0fed1c9833
pvmove: Fix inability to specify LV name when moving RAID, mirror, or thin LV

Top-level LVs (like RAID, mirror or thin) are ignored when determining which
portions of an LV to pvmove.  If the user specified the name of an LV to
move and it was one of the above types, it would be skipped.  The code would
never move on to check whether its sub-LVs needed moving because their names
did not match what the user specified.

The solution is to check whether a sub-LVs is part of the LV whose name was
specified by the user - not just if there was a name match.
pvmove:  Allow moving snapshot/origin.  Disallow converting and merging LVs

The patch allows the user to also pvmove snapshots and origin logical
volumes.  This means pvmove should be able to move all segment types.
I have, however, disallowed moving converting or merging logical volumes.
test: pvmove tests for all the different segment types.

Test moving linear, mirror, snapshot, RAID1,5,10, thinpool, thin
and thin on RAID.  Perform the moves along with a dummy LV and
also without the dummy LV by specifying a logical volume name as
an argument to pvmove.
TEST: Add tests for lvchange actions of RAID under thin

Patch includes RAID1,4,5,6,10 tests for:
- setting writemostly/writebehind
* syncaction changes (i.e. scrubbing operations)
- refresh (i.e. reviving devices after transient failures)
- setting recovery rate (sync I/O throttling)
while the RAID LVs are under a thin-pool (both data and metadata)

* not fully tested because I haven't found a way to force bad
  blocks to be noticed in the testsuite yet.  Works just fine
  when dealing with "real" devices.
TEST: Add a timeout to the harness, killing tests after 2 minutes.
test: Make timeouts a little more robust & verbose.
test: Remove a redundant drain() from the timeout path.
test: Check for flavoured variables earlier.

This is necessary to make LVM_TEST_DEVDIR flavourable, and in turn have flavours
that use the global /dev (which can in turn be managed by udev).
test: Add a new "check_full" target, which also tests with real /dev.

The original "check" target stays confined to a local device directory, while
check_full does 6 flavours, 3 with a local device directory and 3 with the
global /dev directory (the latter are prefixed with "s" for
"system"). I.e.: normal, cluster, lvmetad, snormal, scluster, slvmetad.