Description of problem:

Able to shrink a thin pool metadata LV causes kernel
to complain about the reduced size.

Version-Release number of selected component (if applicable):

kernel 4.2.3-200.fc22 and upstream 4.3.0
lvm 2.02.116(2)

How reproducible:

Always.

Steps to Reproduce:
1. create thin_pool
2. grow thin pool metadata LV
3. shrink  "

Actual results:

Kernel complains about metadata device being too small

Expected results:

lvm2 should prevent reducing pool metadata LV
untill dm-thin gets enhanced to cope with it.


Additional info: