On Mon, Jun 3, 2013 at 11:35 AM, Martin K. Petersen
[off-list ref] wrote:

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"hpa" == H Peter Anvin [off-list ref] writes:

hpa> OK, so the device here says don't do this again, but fails the
hpa> request anyway expecting the block device to pick up the slack.

Yes, the block layer function will resort to writing out zeroes directly
in this case.

MD should not consider a rejected WRITE SAME a failure.

What should md do in the partial success case?  Seems to be a layering
violation to assume that the block layer will retry with zeroes.
Maybe just act on BIO_QUIET to retry the write with REQ_WRITE_SAME
cleared?

--
Dan