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