wip
[dm_interface] don't check the full /dev/mapper/<thing> path before doing a remove.

There's a race with udev anyway.
[thinp] PoolAndDataSizeMatchTests
[thinp] more work on the pool resize tests
dmts: add basic dm-crypt support

dmtest run --suite crypt -n /fio_database_funtime/
add resize_io back...
dmts: add commit_failure_sets_needs_check

test_commit_failure_sets_needs_check(PoolResizeWithSpaceTests):
 kernel: device-mapper: thin: Data device (dm-1) discard unsupported: Disabling discard passdown.
 kernel: bio: create slab <bio-2> at 2
 kernel: device-mapper: thin: 253:4: reached low water mark for data device: sending event.
 kernel: bio: create slab <bio-3> at 3
 kernel: device-mapper: thin: 253:4: reached low water mark for data device: sending event.
 kernel: device-mapper: thin: 253:4: metadata operation 'dm_pool_commit_metadata' failed: error = -5
 kernel: device-mapper: thin: 253:4: aborting current metadata transaction
 kernel: device-mapper: thin: 253:4: switching pool to read-only mode
 kernel: device-mapper: thin: Data device (dm-1) discard unsupported: Disabling discard passdown.
 kernel: device-mapper: thin: 253:4: unable to switch pool to write mode until repaired.
.