commit 29e6bf282f3d7ce3bba98653bdf81d7fc4b83ede
author David Anderson <dvander@google.com> Mon Apr 29 13:54:05 2019 -0700
committer David Anderson <dvander@google.com> Mon May 06 13:59:44 2019 -0700
tree 31bc3f25f11fb8231ce27c38318198596965e8b4
parent be9c2c03109f206ea4244962ee9863cfc123d1d0

Add dm-snapshot targets to libdm and dmctl.

This adds DmTargetSnapshotOrigin and DmTargetSnapshot. The latter target
can handle both "snapshot" and "snapshot-merge" targets. The syntax for
dmctl is as follows:

    dmctl create <name> snapshot <start> <num_sectors> <base_device> \
          <cow_device> <P|N> <chunk_size>
    dmctl create <name> snapshot-merge <start> <num_sectors> <base_device> \
          <cow_device> <chunk_size>
    dmctl create <name> snapshot-origin <start> <num_sectors> <device>

Bug: N/A
Test: libdm_test gtests
Change-Id: I8eef987cb92121e81bedd37b9a66fad04c7a23a3