tree 068716a0537e0f7007a037073c4b7bc608233c1e
parent 3ae4c9deb30a8d5ee305b461625dcb298c9804a9
author Dave Chinner <dchinner@redhat.com> 1282615331 +1000
committer Alex Elder <aelder@sgi.com> 1287432445 -0500

xfs: Introduce XFS_IOC_ZERO_RANGE

XFS_IOC_ZERO_RANGE is the equivalent of an atomic XFS_IOC_UNRESVSP/
XFS_IOC_RESVSP call pair. It enabled ranges of written data to be
turned into zeroes without requiring IO or having to free and
reallocate the extents in the range given as would occur if we had
to punch and then preallocate them separately.  This enables
applications to zero parts of files very quickly without changing
the layout of the files in any way.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>