On Thu, Jul 11, 2019 at 09:48:59AM +0200, Jan Kara wrote:
On Wed 10-07-19 20:08:55, Matthew Wilcox wrote:
On Wed, Jul 10, 2019 at 09:02:04PM +0200, Jan Kara wrote:
@@ -848,7 +853,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev, if (unlikely(dax_is_locked(entry))) { void *old_entry = entry;
entry = get_unlocked_entry(xas);
entry = get_unlocked_entry(xas, 0);/* Entry got punched out / reallocated? */ if (!entry || WARN_ON_ONCE(!xa_is_value(entry)))
I'm not sure about this one. Are we sure there will never be a dirty PMD entry? Even if we can't create one today, it feels like a bit of a landmine to leave for someone who creates one in the future.
I was thinking about this but dax_writeback_one() doesn't really care what entry it gets. Yes, in theory it could get a PMD when previously there was PTE or vice-versa but we check that PFN's match and if they really do match, there's no harm in doing the flushing whatever entry we got back... And the checks are simpler this way.
That's fair. I'll revert this part to the way you had it.
I actually want to get rid of the PFN match check too; it doesn't really buy us much. We already check whether the TOWRITE bit is set, and that should accomplish the same thing.