On Fri, Mar 04, 2016 at 07:06:38PM -0800, Linus Torvalds wrote:

quoted

+       if ((mode & FALLOC_FL_PUNCH_HOLE) &&
+           (!blk_queue_discard(q) || !q->limits.discard_zeroes_data))
+               return -EOPNOTSUPP;

I'm ok with this, but suspect that some users would prefer to just
turn this into ZERO_RANGE silently.

Comments from people who would be expected to use this?

A hole punch should be a hole punch, and not silently allocate blocks
isntead of deallocating them.  It's not even a fallback, it's pretty
much the opposite for some workloads.