include/uapi/linux/falloc.h

   1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2 #ifndef _UAPI_FALLOC_H_
   3 #define _UAPI_FALLOC_H_
   4
   5 #define FALLOC_FL_ALLOCATE_RANGE 0x00 /* allocate range */
   6 #define FALLOC_FL_KEEP_SIZE     0x01 /* default is extend size */
   7 #define FALLOC_FL_PUNCH_HOLE    0x02 /* de-allocates range */
   8 #define FALLOC_FL_NO_HIDE_STALE 0x04 /* reserved codepoint */
   9
  10 /*
  11  * FALLOC_FL_COLLAPSE_RANGE is used to remove a range of a file
  12  * without leaving a hole in the file. The contents of the file beyond
  13  * the range being removed is appended to the start offset of the range
  14  * being removed (i.e. the hole that was punched is "collapsed"),
  15  * resulting in a file layout that looks like the range that was
  16  * removed never existed. As such collapsing a range of a file changes
  17  * the size of the file, reducing it by the same length of the range
  18  * that has been removed by the operation.
  19  *
  20  * Different filesystems may implement different limitations on the
  21  * granularity of the operation. Most will limit operations to
  22  * filesystem block size boundaries, but this boundary may be larger or
  23  * smaller depending on the filesystem and/or the configuration of the
  24  * filesystem or file.
  25  *
  26  * Attempting to collapse a range that crosses the end of the file is
  27  * considered an illegal operation - just use ftruncate(2) if you need
  28  * to collapse a range that crosses EOF.
  29  */
  30 #define FALLOC_FL_COLLAPSE_RANGE        0x08
  31
  32 /*
  33  * FALLOC_FL_ZERO_RANGE is used to convert a range of file to zeros preferably
  34  * without issuing data IO. Blocks should be preallocated for the regions that
  35  * span holes in the file, and the entire range is preferable converted to
  36  * unwritten extents - even though file system may choose to zero out the
  37  * extent or do whatever which will result in reading zeros from the range
  38  * while the range remains allocated for the file.
  39  *
  40  * This can be also used to preallocate blocks past EOF in the same way as
  41  * with fallocate. Flag FALLOC_FL_KEEP_SIZE should cause the inode
  42  * size to remain the same.
  43  */
  44 #define FALLOC_FL_ZERO_RANGE            0x10
  45
  46 /*
  47  * FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
  48  * overwriting any existing data. The contents of the file beyond offset are
  49  * shifted towards right by len bytes to create a hole.  As such, this
  50  * operation will increase the size of the file by len bytes.
  51  *
  52  * Different filesystems may implement different limitations on the granularity
  53  * of the operation. Most will limit operations to filesystem block size
  54  * boundaries, but this boundary may be larger or smaller depending on
  55  * the filesystem and/or the configuration of the filesystem or file.
  56  *
  57  * Attempting to insert space using this flag at OR beyond the end of
  58  * the file is considered an illegal operation - just use ftruncate(2) or
  59  * fallocate(2) with mode 0 for such type of operations.
  60  */
  61 #define FALLOC_FL_INSERT_RANGE          0x20
  62
  63 /*
  64  * FALLOC_FL_UNSHARE_RANGE is used to unshare shared blocks within the
  65  * file size without overwriting any existing data. The purpose of this
  66  * call is to preemptively reallocate any blocks that are subject to
  67  * copy-on-write.
  68  *
  69  * Different filesystems may implement different limitations on the
  70  * granularity of the operation. Most will limit operations to filesystem
  71  * block size boundaries, but this boundary may be larger or smaller
  72  * depending on the filesystem and/or the configuration of the filesystem
  73  * or file.
  74  *
  75  * This flag can only be used with allocate-mode fallocate, which is
  76  * to say that it cannot be used with the punch, zero, collapse, or
  77  * insert range modes.
  78  */
  79 #define FALLOC_FL_UNSHARE_RANGE         0x40
  80
  81 #endif /* _UAPI_FALLOC_H_ */