[dm-devel] block: Fix a WRITE SAME BUG_ON

[Christoph Hellwig]

On Mon, Jan 28, 2019 at 11:54:08PM -0500, Martin K. Petersen wrote:
> That said, now that we have REQ_OP_WRITE_ZEROES (where the LBS is
> irrelevant due to the payload being the ZERO_PAGE), it may be worthwhile
> to remove REQ_OP_WRITE_SAME. I think drbd is the only user relying on a
> non-zero payload. The target code ends up manually iterating, if I
> remember correctly...

I had a series to remove it a while ago, but you wanted to keep it at
that point.  I can resurrect it.