fs: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate (409332b6) · Commits · 戴 / test

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>

fs/open.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -232,7 +232,12 @@ int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)

		/* Return error if mode is not supported */
		if (mode & ~(FALLOC_FL_KEEP_SIZE \| FALLOC_FL_PUNCH_HOLE \|
		FALLOC_FL_COLLAPSE_RANGE))
		FALLOC_FL_COLLAPSE_RANGE \| FALLOC_FL_ZERO_RANGE))
		return -EOPNOTSUPP;

		/* Punch hole and zero range are mutually exclusive */
		if ((mode & (FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_ZERO_RANGE)) ==
		(FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_ZERO_RANGE))
		return -EOPNOTSUPP;

		/* Punch hole must have keep size set */

include/uapi/linux/falloc.h

+14 −0

Original line number	Diff line number	Diff line
		@@ -27,4 +27,18 @@
		*/
		#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

		#endif /* _UAPI_FALLOC_H_ */

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