Additional fixes and changes to lvconvert restructure

These patchset includes bugfixes and feature updates to the recently committed lvconvert changes.

Bug fixes
[ 1/11] Correct 'const' for _lv_mimage_in_sync()
[ 2/11] Don't start polldaemon if conversion failed in early stage [ 3/11] Multiple fixes about to-corelog conversion
[ 4/11] Fix possible mirror image corruption
[ 5/11] Don't insert temporary layer for corelog mirror [ 6/11] init_mirror_in_sync(0) for corelog mirror addition [ 7/11] Fix semantic consistency of mirrorlog option

Feature updates
[ 8/11] Add internal 'CONVERTING' flag for LVs under conversion [ 9/11] Add a new attr field char for the CONVERTING LV [10/11] Warn if lvconvert needs activation to complete conversion [11/11] Start lvconvert polldaemon on activation (like pvmove)

Other things I would like to work on next are:
- Generalization of seg->mirrored_seg as upward link from LV to seg(s) which use the LV.
- Review and fix remove_mirror_images() so that 'removable_pvs' filtering works on stacked mirror.
- Review the suspend code path. I think 'noflush' should be avoided for lower-level mirrors. Otherwise the upper-level mirror can't suspend.
- Remaining patches from the last post:
https://www.redhat.com/archives/lvm-devel/2007-December/msg00045.html
[11/13] Add 'lv_mirrors' field to reporting functions [12/13] Remove hardcoded "_mlog" name from deptree construction [13/13] Allow disk logs for temporary resync mirror
- Creating a script for 'make check'

Thanks,

Jun'ichi Nomura, NEC Corporation of America