I think the two commits below need to be reverted. This is now
preventing me from creating ZFS volumes (and presumably would block
creating LVM volumes too). I don't know how this passed my testing
before and isn't working now, but that seems to be the case.
When I run `virsh vol-create-as --pool=zfs --name=sparse1 --capacity=1G
--format=raw`, target.format is 0 (VIR_STORAGE_FILE_NONE).
Also note that the equivalent code in RBD came in a commit with more
code. So I'm thinking I was on the wrong track with these two patches.
commit bb5f2dc91f43f48ff726aa589bdac546738d2980
Author: Richard Laager <rlaager(a)wiktel.com>
Date: Tue Mar 15 01:17:35 2016 -0500
zfs: Only raw volumes are supported
commit 6682d6219d4595b51f06867e0c30e7efd745f682
Author: Richard Laager <rlaager(a)wiktel.com>
Date: Tue Mar 15 01:17:34 2016 -0500
logical: Only raw volumes are supported
--
Richard