On Tue, May 02, 2017 at 12:16:13AM -0700, Nicholas A. Bellinger wrote: > Or, another options is use bdev_write_zeroes_sectors() to determine when > dev_attrib->unmap_zeroes_data should be set. Yes, that in combination with your patch to use bdev_write_zeroes_sectors for zeroing from write same seems like the right fix.