#ifndef _LINUX_DAX_H
  #define _LINUX_DAX_H
  
  #include <linux/fs.h>
  #include <linux/mm.h>

  #include <linux/radix-tree.h>

  #include <asm/pgtable.h>

  struct iomap_ops;

  /* We use lowest available exceptional entry bit for locking */
  #define RADIX_DAX_ENTRY_LOCK (1 << RADIX_TREE_EXCEPTIONAL_SHIFT)

  ssize_t iomap_dax_rw(struct kiocb *iocb, struct iov_iter *iter,
  		struct iomap_ops *ops);

  ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *,

  		  get_block_t, dio_iodone_t, int flags);

  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 iomap_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
  			struct iomap_ops *ops);

  int dax_fault(struct vm_area_struct *, struct vm_fault *, get_block_t);

  int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
  void dax_wake_mapping_entry_waiter(struct address_space *mapping,
  				   pgoff_t index, bool wake_all);

  
  #ifdef CONFIG_FS_DAX
  struct page *read_dax_sector(struct block_device *bdev, sector_t n);

  void dax_unlock_mapping_entry(struct address_space *mapping, pgoff_t index);

  int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
  		unsigned int offset, unsigned int length);

  #else
  static inline struct page *read_dax_sector(struct block_device *bdev,
  		sector_t n)
  {
  	return ERR_PTR(-ENXIO);
  }

  /* Shouldn't ever be called when dax is disabled. */
  static inline void dax_unlock_mapping_entry(struct address_space *mapping,
  					    pgoff_t index)
  {
  	BUG();
  }

  static inline int __dax_zero_page_range(struct block_device *bdev,
  		sector_t sector, unsigned int offset, unsigned int length)
  {
  	return -ENXIO;
  }

  #endif

  #if defined(CONFIG_TRANSPARENT_HUGEPAGE)

  int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *,

  				unsigned int flags, get_block_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)

  {
  	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)

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

  
  static inline bool dax_mapping(struct address_space *mapping)
  {
  	return mapping->host && IS_DAX(mapping->host);
  }

  
  struct writeback_control;
  int dax_writeback_mapping_range(struct address_space *mapping,
  		struct block_device *bdev, struct writeback_control *wbc);

  #endif