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falloc.h
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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ #ifndef _FALLOC_H_ #define _FALLOC_H_ #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 #endif /* _FALLOC_H_ */