409332b65d
Introduce new FALLOC_FL_ZERO_RANGE flag for fallocate. This has the same functionality as xfs ioctl XFS_IOC_ZERO_RANGE. It can be 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 which should cause the inode size to remain the same. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>
45 lines
1.9 KiB
C
45 lines
1.9 KiB
C
#ifndef _UAPI_FALLOC_H_
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#define _UAPI_FALLOC_H_
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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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#endif /* _UAPI_FALLOC_H_ */
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