#ifndef _UAPI_FALLOC_H_
  #define _UAPI_FALLOC_H_
  
  #define FALLOC_FL_KEEP_SIZE	0x01 /* default is extend size */
  #define FALLOC_FL_PUNCH_HOLE	0x02 /* de-allocates range */
  #define FALLOC_FL_NO_HIDE_STALE	0x04 /* reserved codepoint */

  /*
   * FALLOC_FL_COLLAPSE_RANGE is used to remove a range of a file
   * without leaving a hole in the file. The contents of the file beyond
   * the range being removed is appended to the start offset of the range
   * being removed (i.e. the hole that was punched is "collapsed"),
   * resulting in a file layout that looks like the range that was
   * removed never existed. As such collapsing a range of a file changes
   * the size of the file, reducing it by the same length of the range
   * that has been removed by the operation.
   *
   * Different filesystems may implement different limitations on the
   * granularity of the operation. Most will limit operations to
   * filesystem block size boundaries, but this boundary may be larger or
   * smaller depending on the filesystem and/or the configuration of the
   * filesystem or file.
   *
   * Attempting to collapse a range that crosses the end of the file is
   * considered an illegal operation - just use ftruncate(2) if you need
   * to collapse a range that crosses EOF.
   */
  #define FALLOC_FL_COLLAPSE_RANGE	0x08

  /*
   * FALLOC_FL_ZERO_RANGE is used to convert a range of file to zeros preferably
   * without issuing data IO. Blocks should be preallocated for the regions that
   * span holes in the file, and the entire range is preferable converted to
   * unwritten extents - even though file system may choose to zero out the
   * extent or do whatever which will result in reading zeros from the range
   * while the range remains allocated for the file.
   *
   * This can be also used to preallocate blocks past EOF in the same way as
   * with fallocate. Flag FALLOC_FL_KEEP_SIZE should cause the inode
   * size to remain the same.
   */
  #define FALLOC_FL_ZERO_RANGE		0x10

  /*
   * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
   * overwriting any existing data. The contents of the file beyond offset are
   * shifted towards right by len bytes to create a hole.  As such, this
   * operation will increase the size of the file by len bytes.
   *
   * Different filesystems may implement different limitations on the granularity
   * of the operation. Most will limit operations to filesystem block size
   * boundaries, but this boundary may be larger or smaller depending on
   * the filesystem and/or the configuration of the filesystem or file.
   *
   * Attempting to insert space using this flag at OR beyond the end of
   * the file is considered an illegal operation - just use ftruncate(2) or
   * fallocate(2) with mode 0 for such type of operations.
   */
  #define FALLOC_FL_INSERT_RANGE		0x20

  /*
   * FALLOC_FL_UNSHARE_RANGE is used to unshare shared blocks within the
   * file size without overwriting any existing data. The purpose of this
   * call is to preemptively reallocate any blocks that are subject to
   * copy-on-write.
   *
   * Different filesystems may implement different limitations on the
   * granularity of the operation. Most will limit operations to filesystem
   * block size boundaries, but this boundary may be larger or smaller
   * depending on the filesystem and/or the configuration of the filesystem
   * or file.
   *
   * This flag can only be used with allocate-mode fallocate, which is
   * to say that it cannot be used with the punch, zero, collapse, or
   * insert range modes.
   */
  #define FALLOC_FL_UNSHARE_RANGE		0x40

  #endif /* _UAPI_FALLOC_H_ */