On Sun, May 08, 2016 at 06:46:13PM +0000, Verma, Vishal L wrote:

On Sun, 2016-05-08 at 01:52 -0700, Christoph Hellwig wrote:

quoted

On Fri, May 06, 2016 at 03:53:09PM -0600, Vishal Verma wrote:

quoted

From: Matthew Wilcox <redacted>

dax_clear_sectors() cannot handle poisoned blocks.��These must be
zeroed using the BIO interface instead.��Convert ext2 and XFS to
use
only sb_issue_zerout().

Signed-off-by: Matthew Wilcox <redacted>
[vishal: Also remove the dax_clear_sectors function entirely]
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

Just to make sure:��the existing sb_issue_zerout as in 4.6-rc
is already doing the right thing for DAX?��I've got a pending
patchset
for XFS that introduces another dax_clear_sectors users, but if it's
already safe to use blkdev_issue_zeroout I can switch to that and
avoid
the merge conflict.

I believe so - Jan has moved all unwritten extent conversions out of
DAX with his patch set, and I believe zeroing through the driver is
always fine. Ross or Jan could confirm though.�

Yep, I believe that the existing sb_issue_zeroout() as of v4.6-rc* does the
right thing.  We'll end up calling sb_issue_zeroout() => blkdev_issue_zeroout()
=> __blkdev_issue_zeroout() because we don't have support for discard or
write_same in PMEM.  This will send zero page BIOs to the PMEM driver, which
will do the zeroing as normal writes.