/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPI_FALLOC_H_
#define _UAPI_FALLOC_H_
#define FALLOC_FL_ALLOCATE_RANGE 0x00 /* allocate range */
#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
/*
* FALLOC_FL_WRITE_ZEROES zeroes a specified file range in such a way that
* subsequent writes to that range do not require further changes to the file
* mapping metadata. This flag is beneficial for subsequent pure overwriting
* within this range, as it can save on block allocation and, consequently,
* significant metadata changes. Therefore, filesystems that always require
* out-of-place writes should not support this flag.
*
* Different filesystems may implement different limitations on the
* granularity of the zeroing operation. Most will preferably be accelerated
* by submitting write zeroes command if the backing storage supports, which
* may not physically write zeros to the media.
*
* This flag cannot be specified in conjunction with the FALLOC_FL_KEEP_SIZE.
*/
#define FALLOC_FL_WRITE_ZEROES 0x80
#endif /* _UAPI_FALLOC_H_ */
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