xfs: split the sunit parameter update into two parts

xfs: split the sunit parameter update into two parts

commit 4f5b1b3a8fa07dc8ecedfaf539b3deed8931a73e upstream.

If the administrator provided a sunit= mount option, we need to validate
the raw parameter, convert the mount option units (512b blocks) into the
internal unit (fs blocks), and then validate that the (now cooked)
parameter doesn't screw anything up on disk.  The incore inode geometry
computation can depend on the new sunit option, but a subsequent patch
will make validating the cooked value depends on the computed inode
geometry, so break the sunit update into two steps.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>