falloc.h 2.7 KB

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  1. #ifndef _FALLOC_H_
  2. #define _FALLOC_H_
  3. #define FALLOC_FL_KEEP_SIZE 0x01 /* default is extend size */
  4. #define FALLOC_FL_PUNCH_HOLE 0x02 /* de-allocates range */
  5. #define FALLOC_FL_NO_HIDE_STALE 0x04 /* reserved codepoint */
  6. /*
  7. * FALLOC_FL_COLLAPSE_RANGE is used to remove a range of a file
  8. * without leaving a hole in the file. The contents of the file beyond
  9. * the range being removed is appended to the start offset of the range
  10. * being removed (i.e. the hole that was punched is "collapsed"),
  11. * resulting in a file layout that looks like the range that was
  12. * removed never existed. As such collapsing a range of a file changes
  13. * the size of the file, reducing it by the same length of the range
  14. * that has been removed by the operation.
  15. *
  16. * Different filesystems may implement different limitations on the
  17. * granularity of the operation. Most will limit operations to
  18. * filesystem block size boundaries, but this boundary may be larger or
  19. * smaller depending on the filesystem and/or the configuration of the
  20. * filesystem or file.
  21. *
  22. * Attempting to collapse a range that crosses the end of the file is
  23. * considered an illegal operation - just use ftruncate(2) if you need
  24. * to collapse a range that crosses EOF.
  25. */
  26. #define FALLOC_FL_COLLAPSE_RANGE 0x08
  27. /*
  28. * FALLOC_FL_ZERO_RANGE is used to convert a range of file to zeros preferably
  29. * without issuing data IO. Blocks should be preallocated for the regions that
  30. * span holes in the file, and the entire range is preferable converted to
  31. * unwritten extents - even though file system may choose to zero out the
  32. * extent or do whatever which will result in reading zeros from the range
  33. * while the range remains allocated for the file.
  34. *
  35. * This can be also used to preallocate blocks past EOF in the same way as
  36. * with fallocate. Flag FALLOC_FL_KEEP_SIZE should cause the inode
  37. * size to remain the same.
  38. */
  39. #define FALLOC_FL_ZERO_RANGE 0x10
  40. /*
  41. * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
  42. * overwriting any existing data. The contents of the file beyond offset are
  43. * shifted towards right by len bytes to create a hole. As such, this
  44. * operation will increase the size of the file by len bytes.
  45. *
  46. * Different filesystems may implement different limitations on the granularity
  47. * of the operation. Most will limit operations to filesystem block size
  48. * boundaries, but this boundary may be larger or smaller depending on
  49. * the filesystem and/or the configuration of the filesystem or file.
  50. *
  51. * Attempting to insert space using this flag at OR beyond the end of
  52. * the file is considered an illegal operation - just use ftruncate(2) or
  53. * fallocate(2) with mode 0 for such type of operations.
  54. */
  55. #define FALLOC_FL_INSERT_RANGE 0x20
  56. #endif /* _FALLOC_H_ */