On Thu, 2017-05-11 at 08:26 +0200, hch@lst.de wrote:

On Wed, May 10, 2017 at 09:50:35PM -0700, Nicholas A. Bellinger wrote:

quoted

1) Expose a block_device or request_queue bit to signal 'real LBPRZ'
support up to IBLOCK, in order to maintain SCSI target feature
compatibility.

No way.  If you want to zero use REQ_OP_WRITE_ZEROES..

Yes, I understand that part and it's what the earlier conversion of
IBLOCK to use blkdev_issue_zeroout() already does.

Once the blkdev_issue_zeroout() conversion is in place then LBPRZ can
always be set to one for IBLOCK using blkdev_issue_zeroout().

The point is this is not in -rc1, which as-is breaks LBPRZ compat for a
release.