Merge tag 'dax-fixes-4.20-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull dax fixes from Dan Williams:
 "The last of the known regression fixes and fallout from the Xarray
  conversion of the filesystem-dax implementation.

  On the path to debugging why the dax memory-failure injection test
  started failing after the Xarray conversion a couple more fixes for
  the dax_lock_mapping_entry(), now called dax_lock_page(), surfaced.
  Those plus the bug that started the hunt are now addressed. These
  patches have appeared in a -next release with no issues reported.

  Note the touches to mm/memory-failure.c are just the conversion to the
  new function signature for dax_lock_page().

  Summary:

   - Fix the Xarray conversion of fsdax to properly handle
     dax_lock_mapping_entry() in the presense of pmd entries

   - Fix inode destruction racing a new lock request"

* tag 'dax-fixes-4.20-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  dax: Fix unlock mismatch with updated API
  dax: Don't access a freed inode
  dax: Check page->mapping isn't NULL

1 files changed, 8 insertions, 6 deletions

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 450b28db9533..0dd316a74a29 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -7,6 +7,8 @@
 #include <linux/radix-tree.h>
 #include <asm/pgtable.h>
 
+typedef unsigned long dax_entry_t;
+
 struct iomap_ops;
 struct dax_device;
 struct dax_operations {
@@ -88,8 +90,8 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 		struct block_device *bdev, struct writeback_control *wbc);
 
 struct page *dax_layout_busy_page(struct address_space *mapping);
-bool dax_lock_mapping_entry(struct page *page);
-void dax_unlock_mapping_entry(struct page *page);
+dax_entry_t dax_lock_page(struct page *page);
+void dax_unlock_page(struct page *page, dax_entry_t cookie);
 #else
 static inline bool bdev_dax_supported(struct block_device *bdev,
 		int blocksize)
@@ -122,14 +124,14 @@ static inline int dax_writeback_mapping_range(struct address_space *mapping,
 	return -EOPNOTSUPP;
 }
 
-static inline bool dax_lock_mapping_entry(struct page *page)
+static inline dax_entry_t dax_lock_page(struct page *page)
 {
 	if (IS_DAX(page->mapping->host))
-		return true;
-	return false;
+		return ~0UL;
+	return 0;
 }
 
-static inline void dax_unlock_mapping_entry(struct page *page)
+static inline void dax_unlock_page(struct page *page, dax_entry_t cookie)
 {
 }
 #endif