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