[GIT PULL] dax fixes for v5.13-rc2

[Dan Williams <dan.j.williams@intel.com>]

Hi Linus, please pull from:

  git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
tags/dax-fixes-5.13-rc2

...to receive a fix for a hang condition in the filesystem-dax core
when exercised by virtiofs. This bug has been there from the
beginning, but the condition has not triggered on other filesystems
since they hold a lock over invalidation events.

The changes have appeared in -next with no reported issues. The
patches were originally against v5.12 so you will see a minor conflict
with Willy's nr_exceptional changes. My proposed conflict resolution
appended below.

---

The following changes since commit 9f4ad9e425a1d3b6a34617b8ea226d56a119a717:

  Linux 5.12 (2021-04-25 13:49:08 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
tags/dax-fixes-5.13-rc2

for you to fetch changes up to 237388320deffde7c2d65ed8fc9eef670dc979b3:

  dax: Wake up all waiters after invalidating dax entry (2021-05-07
15:55:44 -0700)

----------------------------------------------------------------
dax fixes for 5.13-rc2

- Fix a hang condition (missed wakeups with virtiofs when invalidating
  entries)

----------------------------------------------------------------
Vivek Goyal (3):
      dax: Add an enum for specifying dax wakup mode
      dax: Add a wakeup mode parameter to put_unlocked_entry()
      dax: Wake up all waiters after invalidating dax entry

 fs/dax.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

diff --cc fs/dax.c
index 69216241392f,df5485b4bddf..62352cbcf0f4
--- a/fs/dax.c
+++ b/fs/dax.c
@@@ -524,8 -535,8 +535,8 @@@ retry

                dax_disassociate_entry(entry, mapping, false);
                xas_store(xas, NULL);   /* undo the PMD join */
-               dax_wake_entry(xas, entry, true);
+               dax_wake_entry(xas, entry, WAKE_ALL);
 -              mapping->nrexceptional--;
 +              mapping->nrpages -= PG_PMD_NR;
                entry = NULL;
                xas_set(xas, index);
        }
@@@ -661,10 -672,10 +672,10 @@@ static int __dax_invalidate_entry(struc
                goto out;
        dax_disassociate_entry(entry, mapping, trunc);
        xas_store(&xas, NULL);
 -      mapping->nrexceptional--;
 +      mapping->nrpages -= 1UL << dax_entry_order(entry);
        ret = 1;
  out:
-       put_unlocked_entry(&xas, entry);
+       put_unlocked_entry(&xas, entry, WAKE_ALL);
        xas_unlock_irq(&xas);
        return ret;
  }