falloc.h (3642B) - Raw
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ 2 #ifndef _FALLOC_H_ 3 #define _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 /* _FALLOC_H_ */