[illumos-Developer] NOW with zvol-only zfs diffs --> iSCSI UNMAP

[Dan McDonald]

Thanks to ZFSers for being patient.

I've taken the following suggestions:

	- Make F_FREESP an ioctl for zvols only.

	- Only modify zvol.c

	- And don't even bother with the txg_wait_sync() call, as it might
          take O(minutes) to complete.

and updated the webrev:

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

to what should be an improvement.  I still have KEBE comments in there which
need to be addressed and removed, so please when you see any, chime in with
your $0.02 for answers.

Thanks,
Dan

p.s. There's rudimentary WRITE SAME support, but it's just at this point a
     front-end to UNMAP.  The real WRITE SAME changes are in-house right now,
     but I hope to have 'em out to here AFTER I push these UNMAP changes.