[PATCH V3] xfs_io: add mremap command

[Christoph Hellwig]

On Fri, Sep 12, 2014 at 11:54:43AM -0500, Eric Sandeen wrote:
> This adds a simple mremap command to xfs_io.
> 
> It does not take a start address; it uses the existing
> start address, so the sized passed will be the new total
> size of the mapping.
> 
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>

Looks good to me, but I'd feel much more comfortable about merging it
if we had an xfstests test case that actually exercises it.