[illumos-Developer] Now with zfs-ops-in-an-ioctl: iSCSI UNMAP (1st draft)

[Dan McDonald]

Hello again!  (Especially ZFSers like Eric.)

I have compiled and modlintlib-checked these changes, but I have not run them
yet.  Why?  Because I wanted to first make sure that I was not on too many
drugs while placing the zvol-specific operations into a nice ZFS_IOC_UNMAP
ioctl.

Here's the webrev:

	http://www.kebe.com/~danmcd/webrevs/unmap/

I'd especially appreciate folks looking at any KEBE comments and answering
the questions there.

Thanks,
Dan