[PATCH 4/5] dax: use sb_issue_zerout instead of calling dax_clear_sectors

[Verma, Vishal L]

On Mon, 2016-03-28 at 16:34 -0700, Dan Williams wrote:

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> Seems kind of sad to fail the fault due to a bad block when we were
> going to zero it anyway, right?  I'm not seeing a compelling reason to
> keep any zeroing in fs/dax.c.

Agreed - but how do we do this? clear_pmem needs to be able to clear an
arbitrary number of bytes, but to go through the driver, we'd need to
send down a bio? If only the driver had an rw_bytes like interface that
could be used by anyone... :)