Update and fix monitoring of thin pool devices

Code adds better support for monitoring of thin pool devices.
update_pool_lv uses DMEVENTD_MONITOR_IGNORE to not manipulate with monitoring.
vgchange & lvchange are checking real thin pool device for existance
as we are using   _tpool  real device and visible LV pool device might not
be even active (_tpool is activated implicitely for any thin volume).
monitor_dev_for_events is another _lv_postorder like code it might be worth
to think about reusing it here - for now update the code to properly
monitory thin volume deps.
For unmonitoring add extra code to check the usage of thin pool - in case it's in use
unmonitoring of thin volume is skipped.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/activate/activate.h b/lib/activate/activate.h
index ccea9919..2b90a7b8 100644
--- a/lib/activate/activate.h
+++ b/lib/activate/activate.h
@@ -36,6 +36,7 @@ struct lv_activate_opts {
 	int no_merging;
 	int real_pool;
 	int is_activate;
+	int skip_in_use;
 	unsigned revert;
 	unsigned read_only;
 };