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57413d8e17
The fallocate system call takes a mode argument, but that argument contains a wild mix of exclusive modes and an optional flags. Replace FALLOC_FL_SUPPORTED_MASK with FALLOC_FL_MODE_MASK, which excludes the optional flag bit, so that we can use switch statement on the value to easily enumerate the cases while getting the check for duplicate modes for free. To make this (and in the future the file system implementations) more readable also add a symbolic name for the 0 mode used to allocate blocks. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20240827065123.1762168-4-hch@lst.de Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Christian Brauner <brauner@kernel.org>
82 lines
3.6 KiB
C
82 lines
3.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_FALLOC_H_
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#define _UAPI_FALLOC_H_
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#define FALLOC_FL_ALLOCATE_RANGE 0x00 /* allocate range */
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#define FALLOC_FL_KEEP_SIZE 0x01 /* default is extend size */
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#define FALLOC_FL_PUNCH_HOLE 0x02 /* de-allocates range */
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#define FALLOC_FL_NO_HIDE_STALE 0x04 /* reserved codepoint */
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/*
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* FALLOC_FL_COLLAPSE_RANGE is used to remove a range of a file
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* without leaving a hole in the file. The contents of the file beyond
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* the range being removed is appended to the start offset of the range
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* being removed (i.e. the hole that was punched is "collapsed"),
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* resulting in a file layout that looks like the range that was
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* removed never existed. As such collapsing a range of a file changes
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* the size of the file, reducing it by the same length of the range
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* that has been removed by the operation.
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*
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* Different filesystems may implement different limitations on the
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* granularity of the operation. Most will limit operations to
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* filesystem block size boundaries, but this boundary may be larger or
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* smaller depending on the filesystem and/or the configuration of the
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* filesystem or file.
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*
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* Attempting to collapse a range that crosses the end of the file is
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* considered an illegal operation - just use ftruncate(2) if you need
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* to collapse a range that crosses EOF.
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*/
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#define FALLOC_FL_COLLAPSE_RANGE 0x08
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/*
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* FALLOC_FL_ZERO_RANGE is used to convert a range of file to zeros preferably
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* without issuing data IO. Blocks should be preallocated for the regions that
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* span holes in the file, and the entire range is preferable converted to
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* unwritten extents - even though file system may choose to zero out the
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* extent or do whatever which will result in reading zeros from the range
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* while the range remains allocated for the file.
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*
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* This can be also used to preallocate blocks past EOF in the same way as
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* with fallocate. Flag FALLOC_FL_KEEP_SIZE should cause the inode
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* size to remain the same.
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*/
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#define FALLOC_FL_ZERO_RANGE 0x10
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/*
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* FALLOC_FL_INSERT_RANGE is use to insert space within the file size without
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* overwriting any existing data. The contents of the file beyond offset are
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* shifted towards right by len bytes to create a hole. As such, this
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* operation will increase the size of the file by len bytes.
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*
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* Different filesystems may implement different limitations on the granularity
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* of the operation. Most will limit operations to filesystem block size
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* boundaries, but this boundary may be larger or smaller depending on
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* the filesystem and/or the configuration of the filesystem or file.
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*
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* Attempting to insert space using this flag at OR beyond the end of
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* the file is considered an illegal operation - just use ftruncate(2) or
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* fallocate(2) with mode 0 for such type of operations.
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*/
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#define FALLOC_FL_INSERT_RANGE 0x20
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/*
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* FALLOC_FL_UNSHARE_RANGE is used to unshare shared blocks within the
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* file size without overwriting any existing data. The purpose of this
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* call is to preemptively reallocate any blocks that are subject to
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* copy-on-write.
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*
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* Different filesystems may implement different limitations on the
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* granularity of the operation. Most will limit operations to filesystem
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* block size boundaries, but this boundary may be larger or smaller
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* depending on the filesystem and/or the configuration of the filesystem
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* or file.
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*
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* This flag can only be used with allocate-mode fallocate, which is
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* to say that it cannot be used with the punch, zero, collapse, or
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* insert range modes.
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*/
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#define FALLOC_FL_UNSHARE_RANGE 0x40
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#endif /* _UAPI_FALLOC_H_ */
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