Routines responsible for polling of in-progress pvmove, snapshot merge
or mirror conversion each used custom lookup functions to find vg and
lv involved in polling.
Especially pvmove used pvname to lookup pvmove in-progress. The future
lvmpolld will poll each operation by vg/lv name (internally by lvid).
Also there're plans to make pvmove able to move non-overlaping ranges
of extents instead of single PVs as of now. This would also require
to identify the opertion in different manner.
The poll_operation_id structure together with daemon_parms structure they
identify unambiguously the polling task.
git://sourceware.org / lvm2.git / commit