1 files changed, 44 insertions, 11 deletions

diff --git a/include/linux/dax.h b/include/linux/dax.h
index e9ea78c1cf98..8d1a5c47945f 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -9,20 +9,32 @@
 struct iomap_ops;
 
 /*
- * We use lowest available bit in exceptional entry for locking, other two
- * bits to determine entry type. In total 3 special bits.
+ * We use lowest available bit in exceptional entry for locking, one bit for
+ * the entry size (PMD) and two more to tell us if the entry is a huge zero
+ * page (HZP) or an empty entry that is just used for locking.  In total four
+ * special bits.
+ *
+ * If the PMD bit isn't set the entry has size PAGE_SIZE, and if the HZP and
+ * EMPTY bits aren't set the entry is a normal DAX entry with a filesystem
+ * block allocation.
  */
-#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 3)
+#define RADIX_DAX_SHIFT (RADIX_TREE_EXCEPTIONAL_SHIFT + 4)
 #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)
-#define RADIX_DAX_PTE (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
-#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
-#define RADIX_DAX_TYPE_MASK (RADIX_DAX_PTE | RADIX_DAX_PMD)
-#define RADIX_DAX_TYPE(entry) ((unsigned long)entry & RADIX_DAX_TYPE_MASK)
-#define RADIX_DAX_SECTOR(entry) (((unsigned long)entry >> RADIX_DAX_SHIFT))
-#define RADIX_DAX_ENTRY(sector, pmd) ((void *)((unsigned long)sector << \
-                RADIX_DAX_SHIFT | (pmd ? RADIX_DAX_PMD : RADIX_DAX_PTE) | \
-                RADIX_TREE_EXCEPTIONAL_ENTRY))
+#define RADIX_DAX_PMD (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 1))
+#define RADIX_DAX_HZP (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 2))
+#define RADIX_DAX_EMPTY (1 << (RADIX_TREE_EXCEPTIONAL_SHIFT + 3))
 
+static inline unsigned long dax_radix_sector(void *entry)
+{
+        return (unsigned long)entry >> RADIX_DAX_SHIFT;
+}
+
+static inline void *dax_radix_locked_entry(sector_t sector, unsigned long flags)
+{
+        return (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | flags |
+                        ((unsigned long)sector << RADIX_DAX_SHIFT) |
+                        RADIX_DAX_ENTRY_LOCK);
+}
 
 ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
                 struct iomap_ops *ops);
@@ -67,6 +79,27 @@ static inline int dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
         return VM_FAULT_FALLBACK;
 }
 
+#ifdef CONFIG_FS_DAX_PMD
+static inline unsigned int dax_radix_order(void *entry)
+{
+        if ((unsigned long)entry & RADIX_DAX_PMD)
+                return PMD_SHIFT - PAGE_SHIFT;
+        return 0;
+}
+int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
+                pmd_t *pmd, unsigned int flags, struct iomap_ops *ops);
+#else
+static inline unsigned int dax_radix_order(void *entry)
+{
+        return 0;
+}
+static inline int dax_iomap_pmd_fault(struct vm_area_struct *vma,
+                unsigned long address, pmd_t *pmd, unsigned int flags,
+                struct iomap_ops *ops)
+{
+        return VM_FAULT_FALLBACK;
+}
+#endif
 int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
 #define dax_mkwrite(vma, vmf, gb)       dax_fault(vma, vmf, gb)