#ifndef _LINUX_DAX_H
  #define _LINUX_DAX_H
  
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <asm/pgtable.h>
  
  ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *, loff_t,
  		  get_block_t, dio_iodone_t, int flags);
  int dax_clear_blocks(struct inode *, sector_t block, long size);
  int dax_zero_page_range(struct inode *, loff_t from, unsigned len, get_block_t);
  int dax_truncate_page(struct inode *, loff_t from, get_block_t);
  int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t,
  		dax_iodone_t);
  int __dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t,
  		dax_iodone_t);

  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *,
  				unsigned int flags, get_block_t, dax_iodone_t);
  int __dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *,
  				unsigned int flags, get_block_t, dax_iodone_t);
  #else
  static inline int dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
  				pmd_t *pmd, unsigned int flags, get_block_t gb,
  				dax_iodone_t di)
  {
  	return VM_FAULT_FALLBACK;
  }
  #define __dax_pmd_fault dax_pmd_fault
  #endif

  int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
  #define dax_mkwrite(vma, vmf, gb, iod)		dax_fault(vma, vmf, gb, iod)
  #define __dax_mkwrite(vma, vmf, gb, iod)	__dax_fault(vma, vmf, gb, iod)

  static inline bool vma_is_dax(struct vm_area_struct *vma)
  {
  	return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
  }

  #endif